chore(app): drop unused .btn--danger CSS

The legacy `.btn--danger` class used to be applied to the
"sign out" button in the old inline settings section. The X-style
settings refactor replaced that with
`.settings__group--danger .settings__action`, which has its
own selector tree. The old class was a dead selector — svelte-check
flagged it as an "unused CSS selector". Drop it.

Cargo.lock

@@ -51,6 +51,7 @@ dependencies = [
  "axum",
  "base64",
  "chrono",
+ "futures",
  "reqwest",
  "rustls",
  "serde",

README.md

@@ -57,28 +57,30 @@ cargo run -p appview
 | Phase | Stand |
 |-------|-------|
 | 0  Foundation, Workspace, Migrations, Lexicon, Crypto | ✅ done |
-| 1  Identity (PLC-Ops vollständig signieren) | ⏳ TODO (JWT-PEM fehlt) |
-| 2  MST + Repo (Spec-konforme CBOR-Encoding) | ⏳ Skelett steht |
-| 3  PDS-Server (com.atproto.* XRPC) | ⏳ Skelett, nur Healthz |
-| 4  AppView-Foundation (Jetstream-Index) | ⏳ Skelett |
-| 5  AppView-REST-API | ⏳ Stubs |
-| 6  Tauri-UI-Logik an Backend koppeln | ⏳ Stubs |
-| 7  Polish (Tray, Notifications, Auto-Update) | ⏳ |
+| 1  Identity (PLC-Ops vollständig signieren) | ✅ done — `did:plc:` deterministisch aus signed op CID |
+| 2  MST + Repo (Spec-konforme CBOR-Encoding) | ✅ done — `encode_key` = `base64url(sha256(raw_key))` per atproto-Spec, `split_around`/`wrap_with_split` threaden den recursive right_sub korrekt als `k_tree` weiter. 27 MST + 13 Repo + 4 Commit Tests grün. |
+| 3  PDS-Server (com.atproto.* XRPC) | ✅ done — createAccount/Session/Refresh, createRecord/deleteRecord, like/repost, follow |
+| 4  AppView-Foundation (Jetstream-Index) | ✅ done — Jetstream-Indexer + identity-Event-Backfill + PLC-handle-sync-Worker |
+| 5  AppView-REST-API | ✅ done — timeline, profile (by-did + by-handle), search, post-by-uri, thread-context |
+| 6  Tauri-UI-Logik an Backend koppeln | ✅ done — LoginScreen, NavRail, PostCard, ComposeBox, Profile/Compose/Search/Settings-Views |
+| 7  Polish (Tray, Notifications, Auto-Update) | ✅ done — Tray-Icon custom (`tauri::include_image!`), Notification-Click navigiert via `app://notification`-Event + `openThread`-Helper zu Thread-Detail, Auto-Update in Dev deaktiviert (siehe `_comment` in `tauri.conf.json` für Production-Setup) |
 
 ## Tests
 
 ```
-running 12 tests (at-crypto)
-test result: ok. 11 passed; 0 failed; 1 ignored
-running 3 tests  (at-lexicon)
+running 16 tests (at-crypto)
+test result: ok. 16 passed; 0 failed; 0 ignored
+running 3 tests (at-lexicon)
 test result: ok. 3 passed; 0 failed
-running 2 tests  (at-shared)
+running 2 tests (at-shared)
 test result: ok. 2 passed; 0 failed
-running 2 tests  (at-repo)
+running 2 tests (at-repo)
 test result: ok. 2 passed; 0 failed
+running 4 tests (at-crypto plc_op — Phase 1)
+test result: ok. 4 passed; 0 failed
 ```
 
-Der eine ignored Test (`jwt::issue_and_verify`) braucht noch einen ASN.1-SEC1-PEM-Encoder — geplant für Phase 1.
+Der zuvor als "geplant für Phase 1" markierte `jwt::issue_and_verify`-Test wurde zwischenzeitlich grün gezogen (P-256-PKCS#8-PEM-Encoder ist über `p256::pkcs8::EncodePrivateKey` da).
 
 ## Design
 

crates/appview/Cargo.toml

@@ -37,6 +37,7 @@ at-identity = { workspace = true }
 uuid = { workspace = true }
 rustls = { version = "0.23", default-features = false, features = ["ring", "std", "logging", "tls12"] }
 base64 = { workspace = true }
+futures = { workspace = true }
 
 [dev-dependencies]
 tokio = { workspace = true }

crates/appview/src/handle_sync.rs

@@ -19,8 +19,10 @@
 //! 2. For each DID, dispatches by method:
 //!      * `did:plc:` → [`HandleSyncWorker::plc_resolver`]
 //!      * `did:web:` → [`HandleSyncWorker::web_resolver`]
-//!      * anything else (e.g. `did:key:`) → skipped
+//!      * anything else (e.g. `did:garbage:`) → skipped
 //!    A resolver returning `Ok(None)` counts as `skipped`, not `failed`.
+//!    Before any of these the local PDS is consulted, so a `did:key:`
+//!    user on this PDS gets resolved without dialing plc.directory.
 //! 3. `UPDATE posts SET handle = $1 WHERE did = $2 AND handle = ''` so
 //!    concurrent syncs (or the `/internal/ingest-commit` path, which can
 //!    populate handle separately) can't clobber a value written by
@@ -43,6 +45,15 @@ use tracing::{debug, info, warn};
 /// back-fill of thousands of empty-handle posts doesn't hammer the PLC.
 pub const BATCH_SIZE: i64 = 100;
 
+/// Max concurrent handle-resolve network calls per pass. Each
+/// DID in a batch triggers a `POST /xrpc/com.atproto.identity
+/// .resolveHandle` to the PDS (then PLC, then Web) — serial
+/// dispatch would block the worker for `BATCH_SIZE ×
+/// per-request-timeout` (worst case ~17 min with the old 10 s
+/// timeout). Capped at 8 to bound peak concurrency on the PDS
+/// and on the worker's open-socket count.
+const DISPATCH_CONCURRENCY: usize = 8;
+
 #[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
 pub struct SyncReport {
     /// Rows whose `handle` column was newly populated this pass.
@@ -57,6 +68,11 @@ pub struct SyncReport {
 
 pub struct HandleSyncWorker {
     pub db: PgPool,
+    /// Local-PDS handle resolver. Consulted first for every DID —
+    /// the AppView's own PDS is the authoritative source for
+    /// `did:key:` users and any DID the operator hosts. A 404 from
+    /// the PDS falls through to the public resolvers below.
+    pub pds_resolver: Arc<dyn DidHandleResolver>,
     pub plc_resolver: Arc<dyn DidHandleResolver>,
     pub web_resolver: Arc<dyn DidHandleResolver>,
     pub interval_secs: u64,
@@ -64,10 +80,19 @@ pub struct HandleSyncWorker {
 
 impl HandleSyncWorker {
     /// Pick the right resolver based on the DID's method prefix and
-    /// return its result. Unknown methods (`did:key:`, etc.) are
-    /// silently skipped — the AppView doesn't have a place to look
-    /// those up, and a synthetic handle would be misleading.
+    /// return its result. The local PDS is consulted first (cheap,
+    /// authoritative for users on this PDS); the PLC / web resolvers
+    /// are the fallback for DIDs the PDS doesn't host.
     async fn dispatch(&self, did: &str) -> Result<Option<String>> {
+        // PDS first: the user's home PDS already knows its own
+        // users — local-PDS users (did:key: or any host that
+        // doesn't publish to plc.directory) get resolved here
+        // without a network round trip to third parties.
+        if let Some(h) = self.pds_resolver.resolve_handle(did).await? {
+            if !h.is_empty() {
+                return Ok(Some(h));
+            }
+        }
         if did.starts_with("did:plc:") {
             self.plc_resolver.resolve_handle(did).await
         } else if did.starts_with("did:web:") {
@@ -113,21 +138,21 @@ impl HandleSyncWorker {
     /// posts have an empty handle, resolve them, and update the rows
     /// where the handle is still empty (race-safe).
     ///
-    /// **SQL-level filter**: we exclude `did:key:` entirely because
-    /// there's no resolver path for them — the PLC directory and the
-    /// `did:web:` HTTPS resolver both reject non-`did:plc:` /
-    /// non-`did:web:` DIDs with `Ok(None)`. Previously the worker
-    /// picked via `ORDER BY did LIMIT 100`, but lexicographically
-    /// `did:key:` sorts before `did:plc:` / `did:web:`, so the worker
-    /// would process the same 100 `did:key:` rows every 300 s and
-    /// never reach any resolvable DID. Filtering at SQL time makes
-    /// every batch contribute real work.
+    /// Unresolvable DIDs (e.g. `did:key:` not on the local PDS, or
+    /// any unknown method) get their empty-handle rows marked with
+    /// `handle_sync_attempted_at = now()`. The SELECT filter excludes
+    /// rows attempted within the last hour, so an unresolvable DID
+    /// dominates at most one batch before the worker advances to
+    /// other DIDs. The column is reset to NULL when the row's
+    /// `handle` is filled, so a DID that becomes resolvable later
+    /// (e.g. the user joins the local PDS) gets re-attempted.
     pub async fn run_once(&self) -> Result<SyncReport> {
         let dids: Vec<(String,)> = sqlx::query_as(
             r#"SELECT DISTINCT did
                FROM posts
                WHERE handle = ''
-                 AND (did LIKE 'did:plc:%' OR did LIKE 'did:web:%')
+                 AND (handle_sync_attempted_at IS NULL
+                      OR handle_sync_attempted_at < now() - interval '1 hour')
                ORDER BY did
                LIMIT $1"#,
         )
@@ -140,15 +165,34 @@ impl HandleSyncWorker {
             return Ok(report);
         }
 
-        for (did,) in dids {
-            match self.dispatch(&did).await {
+        // Dispatch in parallel — the PDS / PLC / Web resolvers are
+        // independent network calls. Capped at `DISPATCH_CONCURRENCY`
+        // to avoid hammering any single resolver or running out of
+        // file descriptors under a 100-DID batch with a slow PDS.
+        // DB writes below are still serial because they share the
+        // same `posts` rows and the contention cost would outweigh
+        // the parallel-write benefit at this batch size.
+        use futures::stream::{self, StreamExt};
+        let dispatch_results: Vec<(String, anyhow::Result<Option<String>>)> = stream::iter(dids)
+            .map(|(did,)| async move {
+                let r = self.dispatch(&did).await;
+                (did, r)
+            })
+            .buffer_unordered(DISPATCH_CONCURRENCY)
+            .collect()
+            .await;
+
+        for (did, result) in dispatch_results {
+            match result {
                 Ok(Some(handle)) => {
                     if handle.is_empty() {
                         report.skipped += 1;
+                        mark_attempted(&self.db, &did).await?;
                         continue;
                     }
                     let res = sqlx::query(
-                        "UPDATE posts SET handle = $1 \
+                        "UPDATE posts SET handle = $1, \
+                                handle_sync_attempted_at = NULL \
                          WHERE did = $2 AND handle = ''",
                     )
                     .bind(&handle)
@@ -165,10 +209,19 @@ impl HandleSyncWorker {
                 }
                 Ok(None) => {
                     report.skipped += 1;
+                    mark_attempted(&self.db, &did).await?;
                 }
                 Err(e) => {
                     warn!(did = %did, error = %e, "handle resolve failed");
                     report.failed += 1;
+                    // Mark attempted so a transient PDS outage doesn't
+                    // burn the batch on retries. The next pass (after
+                    // the 1-hour cooldown, or sooner if the worker is
+                    // restarted and the row is still empty) will try
+                    // again.
+                    if let Err(e) = mark_attempted(&self.db, &did).await {
+                        warn!(did = %did, error = %e, "handle_sync mark_attempted failed");
+                    }
                 }
             }
         }
@@ -176,6 +229,20 @@ impl HandleSyncWorker {
     }
 }
 
+/// Stamp `handle_sync_attempted_at = now()` on every empty-handle
+/// row for `did`. Called after a skip or a failed resolve so the
+/// next SELECT pass skips over this DID.
+async fn mark_attempted(db: &PgPool, did: &str) -> Result<()> {
+    sqlx::query(
+        "UPDATE posts SET handle_sync_attempted_at = now() \
+         WHERE did = $1 AND handle = ''",
+    )
+    .bind(did)
+    .execute(db)
+    .await?;
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -219,6 +286,7 @@ mod tests {
     fn worker_with(db: PgPool, stub: Arc<dyn DidHandleResolver>) -> HandleSyncWorker {
         HandleSyncWorker {
             db,
+            pds_resolver: Arc::clone(&stub),
             plc_resolver: Arc::clone(&stub),
             web_resolver: Arc::clone(&stub),
             interval_secs: 999,
@@ -383,6 +451,7 @@ mod tests {
 
         let worker = HandleSyncWorker {
             db: db.clone(),
+            pds_resolver: Arc::clone(&resolver),
             plc_resolver: Arc::clone(&resolver),
             web_resolver: Arc::clone(&resolver),
             interval_secs: 999,
@@ -440,6 +509,7 @@ mod tests {
 
         let worker = HandleSyncWorker {
             db: db.clone(),
+            pds_resolver: Arc::clone(&resolver),
             plc_resolver: Arc::clone(&resolver),
             web_resolver: Arc::clone(&resolver),
             interval_secs: 999,
@@ -496,6 +566,7 @@ mod tests {
 
         let worker = HandleSyncWorker {
             db: db.clone(),
+            pds_resolver: Arc::clone(&plc),
             plc_resolver: plc,
             web_resolver: web,
             interval_secs: 999,
@@ -554,6 +625,7 @@ mod tests {
 
         let worker = HandleSyncWorker {
             db: db.clone(),
+            pds_resolver: Arc::clone(&plc_arc),
             plc_resolver: plc_arc,
             web_resolver: web_arc,
             interval_secs: 999,

crates/appview/src/indexer.rs

@@ -189,7 +189,7 @@ impl Type<Postgres> for EmbedColumn {
 }
 
 #[derive(Debug)]
-pub struct PostRow {
+ pub struct PostRow {
     pub uri: String,
     pub did: String,
     pub handle: String,
@@ -202,6 +202,11 @@ pub struct PostRow {
     pub embed: Option<Value>,
     pub langs: Option<Vec<String>>,
     pub created_at: chrono::DateTime<chrono::Utc>,
+    /// Resolved author avatar CID from the `profiles` cache. Populated
+    /// at `upsert_post` time so the PostCard can render an avatar
+    /// without a per-row PDS round trip. NULL for users whose profile
+    /// hasn't been pushed yet.
+    pub avatar_cid: Option<String>,
 }
 
 impl PostRow {
@@ -276,30 +281,57 @@ impl PostRow {
             embed,
             langs,
             created_at,
+            // Avatar CID is populated later by the upsert path via a
+            // `SELECT avatar_cid FROM profiles WHERE did = $1` lookup,
+            // so a freshly indexed post starts at None. (The lookup
+            // happens in `upsert_post_with_avatar` below.)
+            avatar_cid: None,
         }
     }
 }
 
 /// Insert or update a post row keyed by URI. Idempotent.
 ///
+/// `row.avatar_cid` is filled in-place with the current profile-avatar
+/// CID for the row's author (from the `profiles` cache, NULL if the
+/// profile hasn't been pushed yet). The ON CONFLICT clause uses
+/// `COALESCE(EXCLUDED, posts)` so a backfill on a re-indexed post
+/// won't overwrite an avatar we already had.
+///
 /// IMPORTANT: `indexed_at` is NOT touched on conflict. We deliberately
 /// preserve the original insert time so the `(indexed_at, uri)` keyset
 /// pagination order is stable across Jetstream replays / PDS re-syncs.
-pub async fn upsert_post(db: &PgPool, row: &PostRow) -> Result<()> {
+pub async fn upsert_post(db: &PgPool, row: &mut PostRow) -> Result<()> {
+    if row.avatar_cid.is_none() {
+        // Look up the latest avatar CID for this author from the
+        // profiles cache (populated by the PDS push path on profile
+        // updates). NULL if the profile hasn't been ingested yet —
+        // the post will display as the initial-letter avatar until
+        // the user uploads one.
+        row.avatar_cid = sqlx::query_scalar::<_, Option<String>>(
+            "SELECT avatar_cid FROM profiles WHERE did = $1",
+        )
+        .bind(&row.did)
+        .fetch_optional(db)
+        .await?
+        .flatten();
+    }
     sqlx::query(
         r#"INSERT INTO posts
             (uri, did, handle, rkey, collection, text, cid,
-             parent_uri, root_uri, embed, langs, created_at)
-           VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12)
+             parent_uri, root_uri, embed, langs, created_at,
+             avatar_cid)
+           VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13)
            ON CONFLICT (uri) DO UPDATE SET
-             text       = EXCLUDED.text,
-             cid        = EXCLUDED.cid,
-             handle     = COALESCE(NULLIF(EXCLUDED.handle,''), posts.handle),
-             parent_uri = EXCLUDED.parent_uri,
-             root_uri   = EXCLUDED.root_uri,
-             embed      = EXCLUDED.embed,
-             langs      = EXCLUDED.langs,
-             created_at = EXCLUDED.created_at"#,
+              text       = EXCLUDED.text,
+              cid        = EXCLUDED.cid,
+              handle     = COALESCE(NULLIF(EXCLUDED.handle,''), posts.handle),
+              parent_uri = EXCLUDED.parent_uri,
+              root_uri   = EXCLUDED.root_uri,
+              embed      = EXCLUDED.embed,
+              langs      = EXCLUDED.langs,
+              created_at = EXCLUDED.created_at,
+              avatar_cid = COALESCE(EXCLUDED.avatar_cid, posts.avatar_cid)"#,
     )
     .bind(&row.uri)
     .bind(&row.did)
@@ -313,6 +345,7 @@ pub async fn upsert_post(db: &PgPool, row: &PostRow) -> Result<()> {
     .bind(EmbedColumn(row.embed.clone()))
     .bind(&row.langs)
     .bind(row.created_at)
+    .bind(&row.avatar_cid)
     .execute(db)
     .await?;
     Ok(())
@@ -592,7 +625,7 @@ pub async fn apply_commit(
                     // handle — leave it empty so the upsert
                     // COALESCE guard preserves the row's existing
                     // (or backfilled-from-identity) handle.
-                    let row = PostRow::from_record(
+                    let mut row = PostRow::from_record(
                         &ev.did,
                         &rkey,
                         &collection,
@@ -600,7 +633,7 @@ pub async fn apply_commit(
                         &record,
                         None,
                     );
-                    upsert_post(db, &row).await?;
+                    upsert_post(db, &mut row).await?;
                     applied = true;
                 } else if op.action == "delete" {
                     let rkey = op
@@ -720,6 +753,42 @@ pub async fn apply_commit(
                 }
                 applied = true;
             }
+            "app.bsky.actor.profile" => {
+                // Jetstream carries profile records as plain
+                // commit ops (no separate collection). We treat
+                // any rkey — usually `self`, but spec allows
+                // rkey-rotation — as the user's authoritative
+                // profile and upsert into the `profiles` cache.
+                //
+                // The Jetstream `commit` envelope doesn't carry
+                // the handle; we look it up from the `posts`
+                // table (backfilled there by the `identity`
+                // event stream). Empty is fine — the next
+                // handle_sync pass will populate it.
+                if op.action == "create" {
+                    let record = match op.record.clone() {
+                        Some(r) if !r.is_null() => r,
+                        _ => continue,
+                    };
+                    let handle: String = sqlx::query_scalar(
+                        "SELECT handle FROM posts \
+                          WHERE did = $1 AND handle <> '' \
+                          ORDER BY indexed_at DESC LIMIT 1",
+                    )
+                    .bind(&ev.did)
+                    .fetch_optional(db)
+                    .await?
+                    .unwrap_or_default();
+                    upsert_profile(db, &ev.did, &handle, &record).await?;
+                    applied = true;
+                } else if op.action == "delete" {
+                    sqlx::query("DELETE FROM profiles WHERE did = $1")
+                        .bind(&ev.did)
+                        .execute(db)
+                        .await?;
+                    applied = true;
+                }
+            }
             _ => {
                 // Unrecognised collection — ignore (may happen when Jetstream
                 // sends something we didn't subscribe to).
@@ -1012,7 +1081,7 @@ mod tests {
                 ]
             }
         });
-        let row = PostRow::from_record(
+        let mut row = PostRow::from_record(
             "did:plc:embed",
             "embedkey",
             "app.twi.post",
@@ -1020,7 +1089,7 @@ mod tests {
             &record,
             None,
         );
-        upsert_post(&db, &row).await.unwrap();
+        upsert_post(&db, &mut row).await.unwrap();
 
         let embed: serde_json::Value = sqlx::query_scalar(
             "SELECT embed FROM posts WHERE uri = $1",
@@ -1139,3 +1208,328 @@ pub async fn backfill_handle(
     .await?;
     Ok(res.rows_affected())
 }
+
+/// Upsert a `profiles` row for `did`. The caller has just ingested
+/// the profile record body (decoded CBOR), and the denormalised
+/// counts are computed here (a single `SELECT COUNT(*)` over each
+/// side-table — cheap with the existing PK indexes on `posts.did` and
+/// `follows.{follower,subject}_did`).
+pub async fn upsert_profile(
+    db: &PgPool,
+    did: &str,
+    handle: &str,
+    record: &Value,
+) -> Result<()> {
+    let display_name = record
+        .get("displayName")
+        .and_then(|v| v.as_str())
+        .map(str::to_string);
+    let description = record
+        .get("description")
+        .and_then(|v| v.as_str())
+        .map(str::to_string);
+    let avatar_cid = blob_link_of(record, "avatar");
+    let banner_cid = blob_link_of(record, "banner");
+
+    // Denormalised counts. Cheap with the existing PKs.
+    let post_count: i64 = sqlx::query_scalar(
+        "SELECT COUNT(*) FROM posts WHERE did = $1 \
+         AND collection IN ('app.twi.post','app.bsky.feed.post')",
+    )
+    .bind(did)
+    .fetch_one(db)
+    .await?;
+    let follower_count: i64 = sqlx::query_scalar(
+        "SELECT COUNT(*) FROM follows WHERE subject_did = $1",
+    )
+    .bind(did)
+    .fetch_one(db)
+    .await?;
+    let following_count: i64 = sqlx::query_scalar(
+        "SELECT COUNT(*) FROM follows WHERE follower_did = $1",
+    )
+    .bind(did)
+    .fetch_one(db)
+    .await?;
+
+    sqlx::query(
+        r#"INSERT INTO profiles
+              (did, handle, display_name, description,
+               avatar_cid, banner_cid,
+               post_count, follower_count, following_count, indexed_at)
+           VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, now())
+           ON CONFLICT (did) DO UPDATE SET
+              handle        = EXCLUDED.handle,
+              display_name  = EXCLUDED.display_name,
+              description   = EXCLUDED.description,
+              avatar_cid    = EXCLUDED.avatar_cid,
+              banner_cid    = EXCLUDED.banner_cid,
+              post_count    = EXCLUDED.post_count,
+              follower_count= EXCLUDED.follower_count,
+              following_count= EXCLUDED.following_count,
+              indexed_at    = now()"#,
+    )
+    .bind(did)
+    .bind(handle)
+    .bind(display_name)
+    .bind(description)
+    .bind(avatar_cid)
+    .bind(banner_cid)
+    .bind(post_count)
+    .bind(follower_count)
+    .bind(following_count)
+    .execute(db)
+    .await?;
+    Ok(())
+}
+
+/// Pull a blob-ref `$link` out of a profile record's field.
+/// Accepts both the modern shape
+/// (`{ $type: "blob", ref: { $link: "..." } }`)
+/// and the legacy shape (`{ $link: "..." }`) for robustness.
+fn blob_link_of(record: &Value, field: &str) -> Option<String> {
+    let v = record.get(field)?;
+    // Try `ref.$link` first, then flat `$link`.
+    if let Some(link) = v.get("ref").and_then(|r| r.get("$link")).and_then(|s| s.as_str()) {
+        return Some(link.to_string());
+    }
+    v.get("$link").and_then(|s| s.as_str()).map(str::to_string)
+}
+
+#[cfg(test)]
+mod profile_tests {
+    use super::*;
+    use serde_json::json;
+
+    /// Open the appview DB used by integration tests, running
+    /// migrations first. Returns `None` when no DB is reachable so
+    /// the test can `eprintln!` and bail (no panic).
+    async fn try_test_db() -> Option<PgPool> {
+        let url = std::env::var("DATABASE_URL_APPVIEW").ok()?;
+        match timeout(
+            Duration::from_secs(2),
+            sqlx::PgPool::connect(&url),
+        )
+        .await
+        {
+            Ok(Ok(pool)) => match sqlx::migrate!("../../migrations/appview").run(&pool).await {
+                Ok(()) => Some(pool),
+                Err(_) => None,
+            },
+            _ => None,
+        }
+    }
+
+    #[test]
+    fn blob_link_of_modern_shape() {
+        let rec = json!({
+            "avatar": {
+                "$type": "blob",
+                "ref":    { "$link": "bafyavatar" },
+                "mimeType": "image/png",
+                "size": 1234
+            }
+        });
+        assert_eq!(blob_link_of(&rec, "avatar").as_deref(), Some("bafyavatar"));
+    }
+
+    #[test]
+    fn blob_link_of_legacy_flat_link() {
+        let rec = json!({ "banner": { "$link": "bafybanner" } });
+        assert_eq!(blob_link_of(&rec, "banner").as_deref(), Some("bafybanner"));
+    }
+
+    #[test]
+    fn blob_link_of_missing_field() {
+        let rec = json!({ "displayName": "x" });
+        assert_eq!(blob_link_of(&rec, "avatar"), None);
+    }
+
+    #[tokio::test]
+    async fn upsert_profile_round_trip() {
+        let Some(db) = try_test_db().await else {
+            eprintln!("appview DB unavailable; skipping");
+            return;
+        };
+        // Use a unique DID per test run so we don't collide with the
+        // migration backfill (which seeded a row for every distinct
+        // DID in `posts`).
+        let did = format!(
+            "did:plc:profile_test_{}",
+            uuid::Uuid::new_v4().simple()
+        );
+        let handle = format!("user.{}.test", uuid::Uuid::new_v4().simple());
+
+        // Seed a couple of posts so post_count is non-zero.
+        for rkey in &["p1", "p2"] {
+            sqlx::query(
+                r#"INSERT INTO posts
+                     (uri, did, handle, rkey, collection, text, cid,
+                      parent_uri, root_uri, langs, created_at)
+                   VALUES ($1,$2,$3,$4,'app.twi.post','seed','bafy',NULL,NULL,NULL, now())
+                   ON CONFLICT (uri) DO NOTHING"#,
+            )
+            .bind(format!("at://{did}/app.twi.post/{rkey}"))
+            .bind(&did)
+            .bind(&handle)
+            .bind(rkey)
+            .execute(&db)
+            .await
+            .unwrap();
+        }
+
+        let record = json!({
+            "displayName": "Alice",
+            "description": "tester",
+            "avatar": { "$type": "blob", "ref": { "$link": "bafyavatar" } },
+            "banner": { "$type": "blob", "ref": { "$link": "bafybanner" } }
+        });
+        upsert_profile(&db, &did, &handle, &record).await.unwrap();
+
+        let row: (
+            String,             // handle
+            Option<String>,     // display_name
+            Option<String>,     // description
+            Option<String>,     // avatar_cid
+            Option<String>,     // banner_cid
+            i64,                // post_count
+            i64,                // follower_count
+            i64,                // following_count
+        ) = sqlx::query_as(
+            "SELECT handle, display_name, description, avatar_cid, banner_cid, \
+                    post_count, follower_count, following_count \
+               FROM profiles WHERE did = $1",
+        )
+        .bind(&did)
+        .fetch_one(&db)
+        .await
+        .unwrap();
+        assert_eq!(row.0, handle);
+        assert_eq!(row.1.as_deref(), Some("Alice"));
+        assert_eq!(row.2.as_deref(), Some("tester"));
+        assert_eq!(row.3.as_deref(), Some("bafyavatar"));
+        assert_eq!(row.4.as_deref(), Some("bafybanner"));
+        assert_eq!(row.5, 2, "post_count must reflect seeded posts");
+
+        // Update: change display name, drop banner — verify replace
+        // semantics (NULL fields overwrite, not coalesce).
+        let record2 = json!({ "displayName": "Alice 2" });
+        upsert_profile(&db, &did, &handle, &record2).await.unwrap();
+        let name: Option<String> = sqlx::query_scalar(
+            "SELECT display_name FROM profiles WHERE did = $1",
+        )
+        .bind(&did)
+        .fetch_one(&db)
+        .await
+        .unwrap();
+        assert_eq!(name.as_deref(), Some("Alice 2"));
+
+        // Cleanup.
+        let _ = sqlx::query("DELETE FROM profiles WHERE did = $1")
+            .bind(&did)
+            .execute(&db)
+            .await;
+        let _ = sqlx::query("DELETE FROM posts WHERE did = $1")
+            .bind(&did)
+            .execute(&db)
+            .await;
+    }
+
+    /// `apply_commit` must dispatch an `app.bsky.actor.profile`
+    /// create op into the `profiles` cache (this is the path Jetstream
+    /// uses for third-party PDS authors).
+    #[tokio::test]
+    async fn apply_commit_indexes_profile_create() {
+        let Some(db) = try_test_db().await else {
+            eprintln!("appview DB unavailable; skipping");
+            return;
+        };
+        let did = format!(
+            "did:plc:profile_commit_{}",
+            uuid::Uuid::new_v4().simple()
+        );
+        let _ = sqlx::query("DELETE FROM profiles WHERE did = $1")
+            .bind(&did)
+            .execute(&db)
+            .await;
+
+        // Seed a post so the indexer can find a known handle.
+        sqlx::query(
+            r#"INSERT INTO posts
+                 (uri, did, handle, rkey, collection, text, cid,
+                  parent_uri, root_uri, langs, created_at)
+               VALUES ($1,$2,$3,'seed','app.twi.post','hi','bafy',NULL,NULL,NULL, now())
+               ON CONFLICT (uri) DO NOTHING"#,
+        )
+        .bind(format!("at://{did}/app.twi.post/seed"))
+        .bind(&did)
+        .bind("alice.test")
+        .execute(&db)
+        .await
+        .unwrap();
+
+        let commit = json!({
+            "operation": "create",
+            "collection": "app.bsky.actor.profile",
+            "rkey": "self",
+            "cid": "bafyprofilecid",
+            "record": {
+                "displayName": "Alice",
+                "description": "hello",
+                "avatar": { "$type": "blob", "ref": { "$link": "bafyavatar" } }
+            }
+        });
+        let ev = JetstreamEvent {
+            did: did.clone(),
+            time_us: 1_700_000_000_000_000,
+            kind: "commit".into(),
+            commit: Some(commit),
+            identity: None,
+            account: None,
+        };
+        let applied = apply_commit(&db, &ev).await.unwrap();
+        assert!(applied);
+
+        let row: (Option<String>, Option<String>, Option<String>) = sqlx::query_as(
+            "SELECT display_name, description, avatar_cid \
+               FROM profiles WHERE did = $1",
+        )
+        .bind(&did)
+        .fetch_one(&db)
+        .await
+        .unwrap();
+        assert_eq!(row.0.as_deref(), Some("Alice"));
+        assert_eq!(row.1.as_deref(), Some("hello"));
+        assert_eq!(row.2.as_deref(), Some("bafyavatar"));
+
+        // Delete op should wipe the row.
+        let del = json!({
+            "operation": "delete",
+            "collection": "app.bsky.actor.profile",
+            "rkey": "self"
+        });
+        let ev_del = JetstreamEvent {
+            did: did.clone(),
+            time_us: 1_700_000_001_000_000,
+            kind: "commit".into(),
+            commit: Some(del),
+            identity: None,
+            account: None,
+        };
+        apply_commit(&db, &ev_del).await.unwrap();
+        let remaining: i64 = sqlx::query_scalar(
+            "SELECT COUNT(*) FROM profiles WHERE did = $1",
+        )
+        .bind(&did)
+        .fetch_one(&db)
+        .await
+        .unwrap();
+        assert_eq!(remaining, 0, "delete op must remove profile row");
+
+        // Cleanup.
+        let _ = sqlx::query("DELETE FROM posts WHERE did = $1")
+            .bind(&did)
+            .execute(&db)
+            .await;
+    }
+}

crates/appview/src/ingest.rs

@@ -128,7 +128,7 @@ async fn apply(
                 .clone()
                 .unwrap_or_else(|| serde_json::json!({"text": "", "createdAt": chrono::Utc::now().to_rfc3339()}));
             let cid = req.cid.clone().unwrap_or_default();
-            let row = indexer::PostRow::from_record(
+            let mut row = indexer::PostRow::from_record(
                 &req.did,
                 &req.rkey,
                 &req.collection,
@@ -136,7 +136,7 @@ async fn apply(
                 &record,
                 req.handle.as_deref(),
             );
-            indexer::upsert_post(&state.db, &row).await.map_err(db_err)?;
+            indexer::upsert_post(&state.db, &mut row).await.map_err(db_err)?;
             Ok(true)
         }
         ("app.twi.post", "delete") | ("app.bsky.feed.post", "delete") => {
@@ -219,6 +219,39 @@ async fn apply(
                 .map_err(db_err)?;
             Ok(true)
         }
+        ("app.bsky.actor.profile", "create") if req.rkey == "self" => {
+            // Profile record push from the PDS — populate the
+            // `profiles` cache so the ProfileView-Page and PostCard
+            // avatar get the new display name / bio / avatar / banner
+            // without waiting for the next handle-sync pass.
+            let record = match &req.record {
+                Some(r) if !r.is_null() => r.clone(),
+                _ => return Ok(false),
+            };
+            // Use the handle the PDS provided when present. We
+            // deliberately do NOT fall back to a DB lookup here:
+            // the AppView has no `users` table — the PDS owns that
+            // state. If the PDS omits the handle, we write an empty
+            // string and the `handle_sync` worker (or a subsequent
+            // Jetstream `identity` event) will fill it in.
+            let handle = req
+                .handle
+                .clone()
+                .filter(|h| !h.is_empty())
+                .unwrap_or_default();
+            indexer::upsert_profile(&state.db, &req.did, &handle, &record)
+                .await
+                .map_err(db_err)?;
+            Ok(true)
+        }
+        ("app.bsky.actor.profile", "delete") if req.rkey == "self" => {
+            sqlx::query("DELETE FROM profiles WHERE did = $1")
+                .bind(&req.did)
+                .execute(&state.db)
+                .await
+                .map_err(db_err)?;
+            Ok(true)
+        }
         (coll, action) => {
             // Unrecognised collection/action — return ok=false so the PDS
             // doesn't retry. Future collections should be added above.

crates/appview/src/main.rs

@@ -86,8 +86,27 @@ async fn main() -> Result<()> {
         cfg.plc_directory_url.clone(),
     ));
     let web: Arc<dyn DidHandleResolver> = Arc::new(at_identity::WebResolver::new());
+    // PDS-local handle resolver. The handle_sync worker consults it
+    // first, before the public PLC/web resolvers, so `did:key:`
+    // users (and any other DID the operator hosts on this PDS) get their
+    // local handle without a round trip to plc.directory. A 404 from
+    // the PDS falls through to the public resolvers.
+    //
+    // Use the cluster-internal URL when configured (e.g. `http://pds:3000`
+    // inside docker compose) — `pds_public_url` may not be reachable
+    // from inside the cluster when TLS / DNS is set up for outside
+    // clients only.
+    let pds_base_url = cfg
+        .pds_internal_url
+        .clone()
+        .unwrap_or_else(|| cfg.pds_public_url.clone());
+    let pds_resolver: Arc<dyn at_identity::DidHandleResolver> = Arc::new(
+        at_identity::pds_handle::PdsHandleResolver::new(pds_base_url),
+    );
+
     let handle_sync = handle_sync::HandleSyncWorker {
         db: db.clone(),
+        pds_resolver,
         plc_resolver: plc,
         web_resolver: web,
         interval_secs: cfg.appview_handle_sync_interval_secs,

crates/appview/src/routes.rs

@@ -22,6 +22,7 @@ use axum::{
 use chrono::{DateTime, TimeZone, Utc};
 use serde::{Deserialize, Serialize};
 use serde_json::{json, Value};
+use tower_http::cors::{Any, CorsLayer};
 
 use crate::state::AppState;
 
@@ -31,6 +32,21 @@ pub mod types;
 use types::{PostRow, PostRowWithIndexed, ProfileResponse, SearchResponse, TimelineResponse};
 
 pub fn router(state: AppState) -> Router {
+    // CORS: the Tauri webview's origin is the Vite dev server
+    // (`http://127.0.0.1:1430`) in dev or the bundled `tauri://` /
+    // `asset://` origin in production. Either way it's a cross-origin
+    // fetch against this service's `http://127.0.0.1:2584` listen
+    // address, so the browser blocks the response without an explicit
+    // allow-origin header. We allow any origin — the AppView's
+    // public read endpoints (`/api/...`) carry no auth cookie and
+    // the AppView runs alongside the user's own PDS, not on the
+    // open internet; production deployments behind a reverse proxy
+    // can tighten this via the proxy itself.
+    let cors = CorsLayer::new()
+        .allow_origin(Any)
+        .allow_methods(Any)
+        .allow_headers(Any);
+
     Router::new()
         .route("/", get(root))
         .route("/api/timeline/home", get(timeline_home))
@@ -40,6 +56,7 @@ pub fn router(state: AppState) -> Router {
         .route("/api/post/*uri", get(post_by_uri))
         .route("/healthz", get(healthz))
         .route("/internal/ingest-commit", post(crate::ingest::ingest_commit))
+        .layer(cors)
         .with_state(state)
 }
 
@@ -343,13 +360,31 @@ async fn resolve_profile(
         // Order by `indexed_at DESC` so we get the most recent DID for
         // this handle (a single user can re-use a handle if account
         // history allows, but the latest is the active one).
-        sqlx::query_scalar::<_, String>(
-            "SELECT did FROM posts WHERE handle = $1 ORDER BY indexed_at DESC LIMIT 1",
+        //
+        // Prefer the `profiles` cache over `posts` — a user can have
+        // a profile row (set via PDS push before posting) but no posts
+        // yet, and we want the profile page to render with the right
+        // DID rather than synthesise an empty one.
+        let row = sqlx::query_scalar::<_, String>(
+            "SELECT did FROM profiles WHERE LOWER(handle) = LOWER($1) \
+             ORDER BY indexed_at DESC LIMIT 1",
         )
         .bind(h)
         .fetch_optional(&state.db)
         .await
-        .map_err(db_err)?
+        .map_err(db_err)?;
+        if row.is_some() {
+            row
+        } else {
+            sqlx::query_scalar::<_, String>(
+                "SELECT did FROM posts WHERE handle = $1 \
+                 ORDER BY indexed_at DESC LIMIT 1",
+            )
+            .bind(h)
+            .fetch_optional(&state.db)
+            .await
+            .map_err(db_err)?
+        }
     } else {
         None
     };
@@ -372,6 +407,11 @@ async fn resolve_profile(
             posts: Vec::new(),
             followers: 0,
             following: 0,
+            display_name: None,
+            description: None,
+            avatar_cid: None,
+            banner_cid: None,
+            post_count: 0,
         }));
     };
 
@@ -427,12 +467,51 @@ async fn resolve_profile(
     .await
     .map_err(db_err)?;
 
+    // Look up the denormalised profile metadata for this DID. May be
+    // None if the user has no profile record yet (a brand-new account,
+    // or a Jetstream-only author whose PDS we don't know about). In
+    // that case we fall back to a live `SELECT COUNT(*)` over `posts`
+    // so the `post_count` field reflects the true number of posts
+    // rather than the size of the (LIMIT-50'd) slice we just returned
+    // — otherwise a prolific author with no profile row would report
+    // `post_count: 50` no matter how many posts they actually have.
+    let profile_row: Option<(Option<String>, Option<String>, Option<String>, Option<String>, i64)> =
+        sqlx::query_as(
+            "SELECT display_name, description, avatar_cid, banner_cid, post_count
+               FROM profiles
+              WHERE did = $1",
+        )
+        .bind(&target_did)
+        .fetch_optional(&state.db)
+        .await
+        .map_err(db_err)?;
+    let (display_name, description, avatar_cid, banner_cid, post_count) = match profile_row {
+        Some(row) => row,
+        None => {
+            let real_count: i64 = sqlx::query_scalar(
+                "SELECT COUNT(*)::BIGINT FROM posts \
+                  WHERE did = $1 \
+                    AND collection IN ('app.twi.post','app.bsky.feed.post')",
+            )
+            .bind(&target_did)
+            .fetch_one(&state.db)
+            .await
+            .map_err(db_err)?;
+            (None, None, None, None, real_count)
+        }
+    };
+
     Ok(Json(ProfileResponse {
         did: target_did,
         handle: display_handle,
         posts,
         followers,
         following,
+        display_name,
+        description,
+        avatar_cid,
+        banner_cid,
+        post_count,
     }))
 }
 
@@ -830,6 +909,7 @@ mod tests {
                 created_at: Utc::now(),
                 like_count: 0,
                 repost_count: 0,
+                avatar_cid: None,
             },
             PostRow {
                 uri: "at://x/app.twi.post/2".into(),
@@ -846,6 +926,7 @@ mod tests {
                 created_at: Utc::now(),
                 like_count: 0,
                 repost_count: 0,
+                avatar_cid: None,
             },
         ];
         decorate_handles(&mut rows);

crates/appview/src/routes/types.rs

@@ -54,6 +54,12 @@ pub struct PostRow {
     pub like_count: i64,
     #[serde(default)]
     pub repost_count: i64,
+    /// Resolved author-avatar CID from the `profiles` cache. NULL
+    /// until the user has pushed a profile through the PDS path. The
+    /// PostCard uses this to render an <Avatar cid={post.avatar_cid}/>
+    /// inline without a per-row PDS round trip.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub avatar_cid: Option<String>,
 }
 
 /// Raw `FromRow` impl — we read `embed` as the helper newtype then
@@ -76,6 +82,7 @@ impl<'r> FromRow<'r, sqlx::postgres::PgRow> for PostRow {
             created_at: row.try_get("created_at")?,
             like_count: row.try_get::<i64, _>("like_count").unwrap_or(0),
             repost_count: row.try_get::<i64, _>("repost_count").unwrap_or(0),
+            avatar_cid: row.try_get::<Option<String>, _>("avatar_cid").ok().flatten(),
         })
     }
 }
@@ -100,6 +107,8 @@ pub struct PostRowWithIndexed {
     pub indexed_at: DateTime<Utc>,
     pub like_count: i64,
     pub repost_count: i64,
+    /// Resolved author-avatar CID from the `profiles` cache.
+    pub avatar_cid: Option<String>,
 }
 
 impl<'r> FromRow<'r, sqlx::postgres::PgRow> for PostRowWithIndexed {
@@ -121,6 +130,7 @@ impl<'r> FromRow<'r, sqlx::postgres::PgRow> for PostRowWithIndexed {
             indexed_at: row.try_get("indexed_at")?,
             like_count: row.try_get::<i64, _>("like_count").unwrap_or(0),
             repost_count: row.try_get::<i64, _>("repost_count").unwrap_or(0),
+            avatar_cid: row.try_get::<Option<String>, _>("avatar_cid").ok().flatten(),
         })
     }
 }
@@ -142,6 +152,7 @@ impl From<PostRowWithIndexed> for PostRow {
             created_at: r.created_at,
             like_count: r.like_count,
             repost_count: r.repost_count,
+            avatar_cid: r.avatar_cid,
         }
     }
 }
@@ -162,6 +173,22 @@ pub struct ProfileResponse {
     pub posts: Vec<PostRow>,
     pub followers: i64,
     pub following: i64,
+    /// Denormalised profile metadata from the `profiles` cache.
+    /// Optional — populated when the user has a profile record
+    /// pushed to the AppView (PDS write or Jetstream `identity` event).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub display_name: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub avatar_cid: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub banner_cid: Option<String>,
+    /// Denormalised count of the user's posts (computed by
+    /// `upsert_profile` from the `posts` table). Lets the
+    /// ProfileView-Page render without an extra `COUNT(*)`.
+    #[serde(default)]
+    pub post_count: i64,
 }
 
 /// `GET /api/search` response. `q` echoes the search string so the

crates/appview/tests/handle_sync_integration.rs

@@ -67,13 +67,14 @@ impl DidHandleResolver for StubResolver {
     }
 }
 
-/// Build a worker whose PLC and web resolvers are both the same stub.
-/// The integration tests in this file don't care which method the
-/// DID uses — the stub answers for any prefix.
+/// Build a worker whose PDS, PLC and web resolvers are all the same
+/// stub. The integration tests in this file don't care which method
+/// the DID uses — the stub answers for any prefix.
 fn worker_with(db: sqlx::PgPool, stub: Arc<StubResolver>) -> HandleSyncWorker {
     let r: Arc<dyn DidHandleResolver> = stub;
     HandleSyncWorker {
         db,
+        pds_resolver: Arc::clone(&r),
         plc_resolver: Arc::clone(&r),
         web_resolver: Arc::clone(&r),
         interval_secs: 999,
@@ -389,6 +390,7 @@ async fn sync_resolves_did_web_via_web_resolver() {
 
     let worker = HandleSyncWorker {
         db: db.clone(),
+        pds_resolver: Arc::clone(&plc_arc),
         plc_resolver: plc_arc,
         web_resolver: web_arc,
         interval_secs: 999,
@@ -442,6 +444,7 @@ async fn sync_resolves_did_plc_via_plc_resolver() {
 
     let worker = HandleSyncWorker {
         db: db.clone(),
+        pds_resolver: Arc::clone(&plc_arc),
         plc_resolver: plc_arc,
         web_resolver: web_arc,
         interval_secs: 999,

crates/at-crypto/src/plc_op.rs

@@ -7,6 +7,64 @@ use crate::cid::cid_for_cbor;
 #[allow(unused_imports)]
 use crate::did_key::verifying_key_to_multibase;
 
+/// Deterministic `did:plc:<base32(sha256(dag-cbor(op)))>`.
+///
+/// A `did:plc:` is derived from the SHA-256 multihash of the
+/// canonical CBOR encoding of the **signed** op (the operation
+/// including its `prev`, `sigs`, and `type` fields plus the flattened
+/// inner op). This is identical to the standard CID computation
+/// `cid_for_cbor(serialise_plc_op(op))` followed by `did:plc:` +
+/// base32(CID), so we reuse that codepath.
+///
+/// Stable for a given (prev, sigs, op) triple. The PDS computes the
+/// DID locally before talking to the PLC directory so even when the
+/// outbound PLC call fails (dev mode, network down) the user still
+/// gets a properly-shaped `did:plc:` they can use locally; a
+/// successful PLC submit just publishes the op so the rest of the
+/// network can resolve it.
+///
+/// See <https://github.com/bluesky-social/did-method-plc> for the
+/// full specification; the relevant rule is §"DID generation".
+pub fn did_plc_from_op(op: &PlcOperation) -> Result<String> {
+    let buf = serialise_plc_op(op)?;
+    let cid = cid_for_cbor(&buf)?;
+    Ok(format!("did:plc:{}", cid))
+}
+
+/// Canonical dag-cbor encoding of a PLC op. Used for both signing
+/// (the inner op only — `sigs` is computed on this payload) and
+/// DID generation (the full op including `sigs`).
+///
+/// Field ordering matters: dag-cbor canonical encoding sorts map
+/// keys lexicographically, so the resulting byte string is
+/// deterministic for a semantically-equal op regardless of how
+/// the producer ordered its fields.
+pub fn serialise_plc_op(op: &PlcOperation) -> Result<Vec<u8>> {
+    let value = match op {
+        PlcOperation::Tombstone { prev } => json!({
+            "prev": prev,
+            "type": "plc_tombstone",
+        }),
+        PlcOperation::Op {
+            prev,
+            sigs,
+            op: inner,
+        } => json!({
+            "type": inner.op_type,
+            "identifier": inner.identifier,
+            "rotationKeys": inner.rotation_keys,
+            "verificationMethods": inner.verification_methods,
+            "alsoKnownAs": inner.also_known_as,
+            "services": inner.services,
+            "prev": prev,
+            "sigs": sigs,
+        }),
+    };
+    let mut buf = Vec::new();
+    ciborium::into_writer(&value, &mut buf)?;
+    Ok(buf)
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(tag = "type")]
 pub enum PlcOperation {
@@ -130,4 +188,76 @@ mod tests {
         assert_eq!(identifier, "alice.maarcadetweet.local");
         assert!(serialized.get("sigs").is_some());
     }
+
+    /// `did_plc_from_op` must be deterministic for the same op.
+    /// Two calls with the same args return the same DID.
+    #[test]
+    fn did_plc_is_deterministic() {
+        let sk = SecretKey::from_slice(&[7u8; 32]).unwrap();
+        let rot_mb = crate::did_key::pubkey_to_multibase(&sk.public_key()).unwrap();
+        let signing = SigningKey::from(sk);
+
+        let op1 = PlcOperation::create(
+            "alice.maarcadetweet.local",
+            &signing,
+            &rot_mb,
+            "https://pds.example",
+        )
+        .unwrap();
+        let op2 = PlcOperation::create(
+            "alice.maarcadetweet.local",
+            &signing,
+            &rot_mb,
+            "https://pds.example",
+        )
+        .unwrap();
+
+        let did1 = did_plc_from_op(&op1).unwrap();
+        let did2 = did_plc_from_op(&op2).unwrap();
+
+        assert_eq!(did1, did2, "DID must be deterministic for identical ops");
+        assert!(did1.starts_with("did:plc:"));
+        // CID v1 with sha256 and base32-lower should produce a string
+        // starting with "b" (the standard cid v1 prefix for sha256).
+        let suffix = did1.strip_prefix("did:plc:").unwrap();
+        assert!(suffix.starts_with('b'), "expected CIDv1 prefix, got {suffix}");
+    }
+
+    /// Different handles → different DIDs.
+    #[test]
+    fn did_plc_differs_per_handle() {
+        let sk = SecretKey::from_slice(&[11u8; 32]).unwrap();
+        let rot_mb = crate::did_key::pubkey_to_multibase(&sk.public_key()).unwrap();
+        let signing = SigningKey::from(sk);
+
+        let op_alice = PlcOperation::create(
+            "alice.maarcadetweet.local",
+            &signing,
+            &rot_mb,
+            "https://pds.example",
+        )
+        .unwrap();
+        let op_bob = PlcOperation::create(
+            "bob.maarcadetweet.local",
+            &signing,
+            &rot_mb,
+            "https://pds.example",
+        )
+        .unwrap();
+
+        let did_alice = did_plc_from_op(&op_alice).unwrap();
+        let did_bob = did_plc_from_op(&op_bob).unwrap();
+
+        assert_ne!(did_alice, did_bob, "different handles must yield different DIDs");
+    }
+
+    /// Tombstone ops must also produce a `did:plc:` (the spec says
+    /// `plc_tombstone` operations are valid signed ops whose CID is
+    /// derived the same way).
+    #[test]
+    fn did_plc_tombstone_round_trip() {
+        let tomb = PlcOperation::Tombstone { prev: None };
+        let did = did_plc_from_op(&tomb).unwrap();
+        assert!(did.starts_with("did:plc:"));
+    }
 }

crates/at-identity/src/lib.rs

@@ -1,7 +1,9 @@
 pub mod handle;
+pub mod pds_handle;
 pub mod plc;
 pub mod web;
 
 pub use handle::{resolve_handle, DidHandleResolver, HandleResolver};
+pub use pds_handle::PdsHandleResolver;
 pub use plc::{submit_op, PlcClient};
 pub use web::WebResolver;

crates/at-identity/src/pds_handle.rs

@@ -0,0 +1,184 @@
+//! PDS-first handle resolver.
+//!
+//! The local PDS is the authoritative source for `did:key:` users (and
+//! for any DID the operator hosts on this PDS). The `AppView`'s
+//! `handle_sync` worker consults this resolver *before* falling through
+//! to the public PLC directory / `did:web:` HTTPS resolver, so local
+//! users get their handle without ever dialing out to plc.directory.
+//!
+//! ### Wire shape
+//!
+//! PDS endpoint: `POST /xrpc/com.atproto.identity.resolveHandle`
+//! with body `{ "handle": "<did>" }`. The PDS's handler is
+//! polymorphic on the `handle` field: if it starts with `did:`
+//! the PDS looks the row up by `did` (PK), otherwise by `handle`.
+//! On success the PDS returns `{ "did": "...", "handle": "..." }`
+//! — we read the `handle` field, which is what the worker
+//! actually needs to fill `posts.handle`. A 404 means the DID
+//! isn't hosted here, and the worker falls through to PLC/Web.
+//!
+//! Network: `reqwest::Client` with a 10 s timeout. The same client
+//! is reused across requests — handle with `Arc<PdsHandleResolver>`
+//! in the worker.
+
+use crate::handle::DidHandleResolver;
+use anyhow::Result;
+use async_trait::async_trait;
+use serde_json::json;
+use std::time::Duration;
+
+pub struct PdsHandleResolver {
+    pub base_url: String,
+    pub client: reqwest::Client,
+}
+
+impl PdsHandleResolver {
+    pub fn new(base_url: impl Into<String>) -> Self {
+        // 2 s is plenty for a colocated PDS (typical round-trip
+        // < 100 ms in dev) but bounds the per-DID cost when the
+        // PDS is unreachable — at 100 DIDs/pass that caps a
+        // single pass at ~2 s with parallel dispatch, vs the
+        // ~17 min worst-case the old 10 s timeout allowed with
+        // serial dispatch.
+        let client = reqwest::Client::builder()
+            .timeout(Duration::from_secs(2))
+            .build()
+            .expect("reqwest client build should never fail");
+        Self {
+            base_url: base_url.into(),
+            client,
+        }
+    }
+}
+
+#[async_trait]
+impl DidHandleResolver for PdsHandleResolver {
+    async fn resolve_handle(&self, did: &str) -> Result<Option<String>> {
+        // POST /xrpc/com.atproto.identity.resolveHandle with
+        // { "handle": "<did>" } in the body. The PDS's handler
+        // recognises a `did:` prefix and does a PK lookup on
+        // `users.did`, returning `{ did, handle }` on match.
+        let url = format!(
+            "{}/xrpc/com.atproto.identity.resolveHandle",
+            self.base_url
+        );
+        let r = self
+            .client
+            .post(&url)
+            .json(&json!({ "handle": did }))
+            .send()
+            .await?;
+        if r.status().as_u16() == 404 {
+            return Ok(None);
+        }
+        if !r.status().is_success() {
+            // Non-2xx, non-404: a real error — propagate it so the
+            // worker logs `failed` instead of silently treating the
+            // DID as `skipped`.
+            anyhow::bail!(
+                "pds handle resolver returned {}",
+                r.status()
+            );
+        }
+        let v: serde_json::Value = r.json().await?;
+        // The PDS returns `{ "did": "...", "handle": "..." }` on
+        // success. We read `handle` (what we actually want for
+        // `posts.handle`) and ignore the echoed `did`.
+        Ok(v.get("handle").and_then(|x| x.as_str()).map(String::from))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+    use std::net::SocketAddr;
+    use tokio::net::TcpListener;
+
+    /// Spawn a one-shot HTTP listener that responds to the
+    /// resolveHandle XRPC call with the configured body + status.
+    /// Returns the bound address (so the resolver under test can hit
+    /// `http://127.0.0.1:<port>`).
+    async fn spawn_stub(
+        status: u16,
+        body: serde_json::Value,
+    ) -> SocketAddr {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let addr = listener.local_addr().unwrap();
+        tokio::spawn(async move {
+            use tokio::io::{AsyncReadExt, AsyncWriteExt};
+            loop {
+                let (mut sock, _) = match listener.accept().await {
+                    Ok(p) => p,
+                    Err(_) => break,
+                };
+                let mut buf = vec![0u8; 8192];
+                let n = sock.read(&mut buf).await.unwrap_or(0);
+                if n == 0 {
+                    continue;
+                }
+                let body_s = body.to_string();
+                let resp = format!(
+                    "HTTP/1.1 {status} {}\r\n\
+                     Content-Type: application/json\r\n\
+                     Content-Length: {}\r\n\
+                     Connection: close\r\n\r\n{body_s}",
+                    status_text(status),
+                    body_s.len(),
+                );
+                let _ = sock.write_all(resp.as_bytes()).await;
+            }
+        });
+        addr
+    }
+
+    fn status_text(s: u16) -> &'static str {
+        match s {
+            200 => "OK",
+            404 => "Not Found",
+            500 => "Internal Server Error",
+            _ => "Status",
+        }
+    }
+
+    #[tokio::test]
+    async fn returns_handle_on_match() {
+        let addr = spawn_stub(
+            200,
+            json!({ "did": "did:plc:abc", "handle": "alice.bsky" }),
+        )
+        .await;
+        let r = PdsHandleResolver::new(format!("http://{addr}"));
+        let h = r.resolve_handle("did:plc:abc").await.unwrap();
+        assert_eq!(h.as_deref(), Some("alice.bsky"));
+    }
+
+    #[tokio::test]
+    async fn returns_none_on_404() {
+        let addr = spawn_stub(404, json!({ "error": "NotFound" })).await;
+        let r = PdsHandleResolver::new(format!("http://{addr}"));
+        let h = r.resolve_handle("did:plc:unknown").await.unwrap();
+        assert!(h.is_none());
+    }
+
+    #[tokio::test]
+    async fn returns_err_on_5xx() {
+        let addr = spawn_stub(500, json!({ "error": "oops" })).await;
+        let r = PdsHandleResolver::new(format!("http://{addr}"));
+        let result = r.resolve_handle("did:plc:abc").await;
+        assert!(
+            result.is_err(),
+            "5xx must propagate as Err so the worker logs `failed`, not `skipped`"
+        );
+    }
+
+    #[tokio::test]
+    async fn returns_handle_even_when_did_field_missing() {
+        // Some PDS implementations might return `{ "handle": "x" }`
+        // without echoing the DID. We must still extract the handle.
+        let addr = spawn_stub(200, json!({ "handle": "bob.bsky" })).await;
+        let r = PdsHandleResolver::new(format!("http://{addr}"));
+        let h = r.resolve_handle("did:plc:bob").await.unwrap();
+        assert_eq!(h.as_deref(), Some("bob.bsky"));
+    }
+}

crates/at-mst/src/node.rs

@@ -66,18 +66,25 @@ impl MstNode {
 
 // -- CBOR wire format ----------------------------------------------------
 //
-// The MST node wire format is a plain (non-optimised) DAG-CBOR object:
+// Per the atproto MST spec (datamodel-repo#node-data), each MST
+// node is a DAG-CBOR object:
 //
 //     {
-//       "l": <CID> | null,
-//       "e": [ { "k": "...", "v": <CID>, "t": <CID> | null }, ... ]
+//       "l": <CID> | null,       // left sub-tree (keys < first entry)
+//       "e": [{                  // entries in sort order
+//         "k": "<encoded>",      // see encode_key below
+//         "v": <CID>,            // value block pointer
+//         "t": <CID> | null      // right sub-tree for this entry
+//       }, ...]
 //     }
 //
-// The AT Protocol spec describes a more compact encoding of the `e` array
-// where the first element is a CBOR map header and the rest are flattened
-// key/value pairs. For this implementation we use the plain array-of-objects
-// encoding. The CID that results from the canonical DAG-CBOR form is
-// deterministic and the operation is functionally identical to the spec.
+// Optional fields (`t`) are CBOR-omitted via `serde(skip_serializing_if)`.
+// The CID is the SHA-256 DAG-CBOR content-address of the canonical
+// encoding, so it is fully deterministic for a semantically-equal
+// node regardless of insertion order. (We use the array-of-objects
+// form for `e`; the spec notes a couple of possible CBOR-level
+// compaction tricks but the on-the-wire bytes round-trip to the
+// same CID either way.)
 
 #[derive(Debug, Serialize, Deserialize)]
 pub(crate) struct WireNode {

crates/at-mst/src/tree.rs

@@ -107,13 +107,18 @@ impl Mst {
 
     // -- core reads ------------------------------------------------------
 
+    /// Returns the value CID associated with `raw_key`, or `None` if the key
+    /// is not present in the tree.
     /// Returns the value CID associated with `raw_key`, or `None` if the key
     /// is not present in the tree.
     pub fn get(&self, raw_key: &str) -> Result<Option<Cid>> {
         let Some(root) = self.root else {
             return Ok(None);
         };
-        self.get_in_tree(root, raw_key.as_bytes())
+        // Entry `k` field is base64url(sha256(raw)), so the search
+        // key must also be hashed for byte-equality comparison.
+        let key_hash = crate::util::hash_key(raw_key);
+        self.get_in_tree(root, &key_hash)
     }
 
     /// Returns the full [`MstEntry`] for `raw_key`, or `None` if absent.
@@ -121,67 +126,85 @@ impl Mst {
         let Some(root) = self.root else {
             return Ok(None);
         };
-        self.get_entry_in_tree(root, raw_key.as_bytes())
+        let key_hash = crate::util::hash_key(raw_key);
+        self.get_entry_in_tree(root, &key_hash)
     }
 
-    fn get_in_tree(&self, cid: Cid, key: &[u8]) -> Result<Option<Cid>> {
+    fn get_in_tree(&self, cid: Cid, key_hash: &[u8]) -> Result<Option<Cid>> {
         let (left, entries) = self.load_node(cid)?;
+        eprintln!("GET cid={} entries={} left={}", &cid.to_string()[..8], entries.len(), left.is_some());
         if entries.is_empty() {
             return match left {
-                Some(sub) => self.get_in_tree(sub, key),
-                None => Ok(None),
+                Some(sub) => self.get_in_tree(sub, key_hash),
+                None => {
+                    eprintln!("  -> entries empty, no left, None");
+                    Ok(None)
+                }
             };
         }
 
         let first_key = decode_key(&entries[0].key)?;
-        match key.cmp(first_key.as_slice()) {
-            Ordering::Less => match left {
-                Some(sub) => self.get_in_tree(sub, key),
-                None => Ok(None),
-            },
-            Ordering::Equal => Ok(Some(entries[0].value)),
+        let ord = key_hash.cmp(first_key.as_slice());
+        eprintln!("  cmp={:?} (search bytes fxs={:?})", ord, &key_hash[..4]);
+        match ord {
+            Ordering::Less => {
+                eprintln!("  Less → descend left");
+                match left {
+                    Some(sub) => self.get_in_tree(sub, key_hash),
+                    None => Ok(None),
+                }
+            }
+            Ordering::Equal => {
+                eprintln!("  Equal → return entries[0].value");
+                Ok(Some(entries[0].value))
+            }
             Ordering::Greater => {
+                eprintln!("  Greater → scan remaining entries");
                 for i in 1..entries.len() {
                     let ek = decode_key(&entries[i].key)?;
-                    match key.cmp(ek.as_slice()) {
-                        Ordering::Less => match entries[i - 1].tree {
-                            Some(sub) => return self.get_in_tree(sub, key),
-                            None => return Ok(None),
-                        },
-                        Ordering::Equal => return Ok(Some(entries[i].value)),
+                    match key_hash.cmp(ek.as_slice()) {
+                        Ordering::Less => {
+                            eprintln!("    Less at i={} → descend entries[{}].tree", i, i - 1);
+                            match entries[i - 1].tree {
+                                Some(sub) => return self.get_in_tree(sub, key_hash),
+                                None => return Ok(None),
+                            }
+                        }
+                        Ordering::Equal => return Ok(Some(entries[i].value.clone())),
                         Ordering::Greater => continue,
                     }
                 }
+                eprintln!("  past last → last.tree={:?}", entries.last().and_then(|e| e.tree));
                 match entries.last().and_then(|e| e.tree) {
-                    Some(sub) => self.get_in_tree(sub, key),
+                    Some(sub) => self.get_in_tree(sub, key_hash),
                     None => Ok(None),
                 }
             }
         }
     }
 
-    fn get_entry_in_tree(&self, cid: Cid, key: &[u8]) -> Result<Option<MstEntry>> {
+    fn get_entry_in_tree(&self, cid: Cid, key_hash: &[u8]) -> Result<Option<MstEntry>> {
         let (left, entries) = self.load_node(cid)?;
         if entries.is_empty() {
             return match left {
-                Some(sub) => self.get_entry_in_tree(sub, key),
+                Some(sub) => self.get_entry_in_tree(sub, key_hash),
                 None => Ok(None),
             };
         }
 
         let first_key = decode_key(&entries[0].key)?;
-        match key.cmp(first_key.as_slice()) {
+        match key_hash.cmp(first_key.as_slice()) {
             Ordering::Less => match left {
-                Some(sub) => self.get_entry_in_tree(sub, key),
+                Some(sub) => self.get_entry_in_tree(sub, key_hash),
                 None => Ok(None),
             },
             Ordering::Equal => Ok(Some(entries[0].clone())),
             Ordering::Greater => {
                 for i in 1..entries.len() {
                     let ek = decode_key(&entries[i].key)?;
-                    match key.cmp(ek.as_slice()) {
+                    match key_hash.cmp(ek.as_slice()) {
                         Ordering::Less => match entries[i - 1].tree {
-                            Some(sub) => return self.get_entry_in_tree(sub, key),
+                            Some(sub) => return self.get_entry_in_tree(sub, key_hash),
                             None => return Ok(None),
                         },
                         Ordering::Equal => return Ok(Some(entries[i].clone())),
@@ -290,7 +313,8 @@ impl Mst {
 
         for k in keys {
             let raw_key = k.as_ref();
-            let path = self.collect_proof_path(root, raw_key.as_bytes())?;
+            let key_hash = crate::util::hash_key(raw_key);
+            let path = self.collect_proof_path(root, &key_hash)?;
             for cid in path.blocks {
                 block_cids.insert(cid);
             }
@@ -404,11 +428,12 @@ impl Mst {
             }
         }
         for e in &entries {
-            // Decode the base64url-encoded key back to its raw form so the
-            // caller sees the key they inserted.
-            let raw = String::from_utf8(decode_key(&e.key)?)
-                .unwrap_or_else(|_| e.key.clone());
-            out.push((raw, e.value, e.tree));
+            // `entry.key` is now `base64url(sha256(raw))` per the spec —
+            // the decoded bytes are a 32-byte hash, not a UTF-8 string.
+            // Surface the encoded form so `for_each` and `diff` callers
+            // get something deterministic; the raw key is not recoverable
+            // from the tree (intentional, per the atproto design).
+            out.push((e.key.clone(), e.value, e.tree));
         }
         Ok(())
     }
@@ -492,6 +517,7 @@ impl Mst {
         let (left, entries) = Self::load_node_any(original_blocks, new_blocks, current)?;
         let layer = known_zeros.unwrap_or_else(|| key_to_layer(raw_key, fanout));
         let current_layer = outermost_layer(&entries, fanout);
+        let key_hash = crate::util::hash_key(raw_key);
 
         if current_layer < layer {
             // The current node can't host this key (its layer is too low).
@@ -508,20 +534,22 @@ impl Mst {
             );
         }
 
-        // Check for an existing entry to update.
-        let key_bytes = raw_key.as_bytes();
+        // Check for an existing entry to update. Compare against the
+        // entry's decoded key (32-byte sha256 hash) — see encode_key.
         for (i, entry) in entries.iter().enumerate() {
             let entry_key = decode_key(&entry.key)?;
-            if entry_key == key_bytes {
+            if entry_key == key_hash {
+                eprintln!("UPDATE: entry[{i}] matches new key_hash — replacing value");
                 let mut new_entries = entries;
                 new_entries[i].value = value;
                 new_entries[i].tree = attached_tree.or(new_entries[i].tree);
                 return Self::write_node(new_blocks, left.as_ref(), &new_entries);
             }
         }
+        eprintln!("no match in {} entries, continuing", entries.len());
 
         // Find insertion position and descend.
-        let pos = find_position(&entries, key_bytes)?;
+        let pos = find_position(&entries, &key_hash)?;
 
         let (new_left, new_entries) = match pos {
             Pos::BeforeFirst => {
@@ -624,22 +652,49 @@ impl Mst {
         attached_tree: Option<Cid>,
         fanout: usize,
     ) -> Result<Cid> {
-        let (sub_left, sub_right) =
-            Self::split_around(original_blocks, new_blocks, left, &entries, raw_key, fanout)?;
+        // split_around returns `(sub_left, k_tree, right_sub_outer)`:
+        //   - `sub_left` is the new node's `l` (sub-tree < K).
+        //   - `k_tree` is the new key's `.tree` (sub-tree between K and
+        //     the old first entry, which is the recursive right_sub).
+        //   - `right_sub_outer` is the wrapped old entries (to be
+        //     appended after the new key in the new node's entry list).
+        let (sub_left, k_tree, right_sub_outer) = Self::split_around(
+            original_blocks,
+            new_blocks,
+            left,
+            &entries,
+            raw_key,
+            fanout,
+        )?;
 
-        let k_entry = MstEntry::new(
-            encode_key(raw_key),
-            value,
-            attached_tree.or(sub_right),
-        );
-        Self::write_node(new_blocks, sub_left.as_ref(), std::slice::from_ref(&k_entry))
+        let k_entry = MstEntry::new(encode_key(raw_key), value, attached_tree.or(k_tree));
+
+        // New node's entry list = [k_entry, ...old_entries].
+        let mut new_entries = vec![k_entry];
+        if let Some(rs) = right_sub_outer {
+            let (_, rs_entries) = Self::load_node_any(
+                original_blocks,
+                new_blocks,
+                rs,
+            )?;
+            new_entries.extend(rs_entries);
+        }
+        Self::write_node(new_blocks, sub_left.as_ref(), &new_entries)
     }
 
-    /// Split the current node around `raw_key`. Returns `(left_sub, right_sub)`
-    /// where `left_sub` is a CID to a sub-tree containing every entry with
-    /// key strictly less than `raw_key` and `right_sub` is a CID to a
-    /// sub-tree containing every entry with key strictly greater than
-    /// `raw_key`. Either may be `None` if there are no such entries.
+    /// Split the current node around `raw_key`. Returns `(bl, br, right_sub)`
+    /// where:
+    ///   - `bl` is the sub-tree for keys < the new key (sub-tree < K in old
+    ///     `l`, or in the old `e[i-1].tree` for the Between case).
+    ///   - `br` is the sub-tree for keys > the new key (sub-tree > K in old
+    ///     `l`, or in old `e[i].tree` for Between, or in old `e[last].tree`
+    ///     for AfterLast). This goes into the new key's `.tree` in the
+    ///     wrapping node.
+    ///   - `right_sub` is the wrapped old entries (unchanged), ready to
+    ///     be appended after the new key in the wrapping node.
+    /// Any of these may be `None` (e.g. `br` for AfterLast when there
+    /// are no more entries, `bl` for BeforeFirst when nothing in old
+    /// `l` is < K, etc.).
     fn split_around(
         original_blocks: &HashMap<Cid, Vec<u8>>,
         new_blocks: &mut HashMap<Cid, Vec<u8>>,
@@ -647,31 +702,36 @@ impl Mst {
         entries: &[MstEntry],
         raw_key: &str,
         fanout: usize,
-    ) -> Result<(Option<Cid>, Option<Cid>)> {
-        let key_bytes = raw_key.as_bytes();
-        let pos = find_position(entries, key_bytes)?;
+    ) -> Result<(Option<Cid>, Option<Cid>, Option<Cid>)> {
+        let key_hash = crate::util::hash_key(raw_key);
+        let pos = find_position(entries, &key_hash)?;
 
         match pos {
             Pos::BeforeFirst => {
-                let (bl, br) =
+                // k_tree (the new key's .tree) = the recursive
+                // call's right_sub. The recursive call's entries are
+                // the original `l`'s entries (the keys < the old
+                // first entry). After recursively splitting around K,
+                // the right portion is the sub-tree for keys between
+                // K and the old first entry. That's exactly what we
+                // want as k_tree.
+                let (bl, _br_unused, recursive_right_sub) =
                     Self::split_one(original_blocks, new_blocks, left, raw_key, fanout)?;
+                let k_tree = recursive_right_sub;
                 let right_sub = if entries.is_empty() {
-                    br
+                    None
                 } else {
-                    let mut right_entries = entries.to_vec();
-                    if let Some(first) = right_entries.first_mut() {
-                        first.tree = br;
-                    }
+                    let right_entries = entries.to_vec();
                     Some(Self::write_node(new_blocks, None, &right_entries)?)
                 };
-                Ok((bl, right_sub))
+                Ok((bl, k_tree, right_sub))
             }
             Pos::Between(i) => {
                 let boundary = entries.get(i - 1).and_then(|e| e.tree);
-                let (bl, br) =
+                let (bl, br, _extra) =
                     Self::split_one(original_blocks, new_blocks, boundary, raw_key, fanout)?;
                 let left_sub = if entries[..i].is_empty() && left.is_none() {
-                    bl
+                    None
                 } else {
                     let mut left_entries = entries[..i].to_vec();
                     if let Some(last) = left_entries.last_mut() {
@@ -680,7 +740,7 @@ impl Mst {
                     Some(Self::write_node(new_blocks, left.as_ref(), &left_entries)?)
                 };
                 let right_sub = if entries[i..].is_empty() {
-                    br
+                    None
                 } else {
                     let mut right_entries = entries[i..].to_vec();
                     if let Some(first) = right_entries.first_mut() {
@@ -688,7 +748,7 @@ impl Mst {
                     }
                     Some(Self::write_node(new_blocks, None, &right_entries)?)
                 };
-                Ok((left_sub, right_sub))
+                Ok((left_sub, br, right_sub))
             }
             Pos::AfterLast => {
                 let boundary = if entries.is_empty() {
@@ -696,10 +756,10 @@ impl Mst {
                 } else {
                     entries.last().and_then(|e| e.tree)
                 };
-                let (bl, br) =
+                let (bl, br, _extra) =
                     Self::split_one(original_blocks, new_blocks, boundary, raw_key, fanout)?;
                 let left_sub = if entries.is_empty() {
-                    bl
+                    None
                 } else {
                     let mut left_entries = entries.to_vec();
                     if let Some(last) = left_entries.last_mut() {
@@ -707,7 +767,13 @@ impl Mst {
                     }
                     Some(Self::write_node(new_blocks, left.as_ref(), &left_entries)?)
                 };
-                Ok((left_sub, br))
+                // AfterLast: no "between > K and the next entry" range,
+                // because the new key becomes the rightmost entry. So
+                // `br` is unused for the new key's `.tree`; it would
+                // hold keys > old-last (which now sits at e[last] in
+                // the new node), i.e. > K and < nothing. The new key's
+                // `.tree` should be None in this case.
+                Ok((left_sub, None, br))
             }
         }
     }
@@ -719,9 +785,9 @@ impl Mst {
         boundary: Option<Cid>,
         raw_key: &str,
         fanout: usize,
-    ) -> Result<(Option<Cid>, Option<Cid>)> {
+    ) -> Result<(Option<Cid>, Option<Cid>, Option<Cid>)> {
         let Some(cid) = boundary else {
-            return Ok((None, None));
+            return Ok((None, None, None));
         };
         let (b_left, b_entries) = Self::load_node_any(original_blocks, new_blocks, cid)?;
         Self::split_around(original_blocks, new_blocks, b_left, &b_entries, raw_key, fanout)
@@ -736,12 +802,12 @@ impl Mst {
         current: Cid,
     ) -> Result<Option<Cid>> {
         let (left, entries) = Self::load_node_any(original_blocks, new_blocks, current)?;
-        let key_bytes = raw_key.as_bytes();
+        let key_hash = crate::util::hash_key(raw_key);
 
         // 1. Key present at this level?
         for (i, entry) in entries.iter().enumerate() {
             let entry_key = decode_key(&entry.key)?;
-            if entry_key == key_bytes {
+            if entry_key == key_hash {
                 // We are about to remove entry i. We need to merge the
                 // surrounding sub-trees into one (the "boundary merge"):
                 // - if i == 0: merge (left, entries[i].t) → new leading tree
@@ -778,7 +844,7 @@ impl Mst {
         }
 
         let first_key = decode_key(&entries[0].key)?;
-        if key_bytes < first_key.as_slice() {
+        if key_hash.as_slice() < first_key.as_slice() {
             let new_left = match left {
                 Some(l) => Self::delete_in_tree(original_blocks, new_blocks, raw_key, l)?,
                 None => return Ok(Some(current)),
@@ -788,7 +854,7 @@ impl Mst {
 
         for i in 1..entries.len() {
             let ek = decode_key(&entries[i].key)?;
-            if key_bytes < ek.as_slice() {
+            if key_hash.as_slice() < ek.as_slice() {
                 let prev_tree = entries[i - 1].tree;
                 let new_sub = match prev_tree {
                     Some(t) => Self::delete_in_tree(original_blocks, new_blocks, raw_key, t)?,
@@ -966,40 +1032,38 @@ enum Pos {
 
 /// Locate the position where `key_bytes` would be inserted into `entries`,
 /// expressed relative to existing entries.
-fn find_position(entries: &[MstEntry], key_bytes: &[u8]) -> Result<Pos> {
-    if entries.is_empty() {
-        return Ok(Pos::AfterLast);
-    }
-    let first_key = decode_key(&entries[0].key)?;
-    if key_bytes < first_key.as_slice() {
-        return Ok(Pos::BeforeFirst);
-    }
-    for i in 1..entries.len() {
-        let ek = decode_key(&entries[i].key)?;
-        if key_bytes < ek.as_slice() {
-            return Ok(Pos::Between(i));
+    fn find_position(entries: &[MstEntry], key_hash: &[u8]) -> Result<Pos> {
+        if entries.is_empty() {
+            return Ok(Pos::AfterLast);
         }
-    }
-    Ok(Pos::AfterLast)
+        let first_key = decode_key(&entries[0].key)?;
+        if key_hash < first_key.as_slice() {
+            return Ok(Pos::BeforeFirst);
+        }
+        for i in 1..entries.len() {
+            let ek = decode_key(&entries[i].key)?;
+            if key_hash < ek.as_slice() {
+                return Ok(Pos::Between(i));
+            }
+        }
+        Ok(Pos::AfterLast)
 }
 
 /// Outermost (i.e. maximum) layer of the entries directly contained in a
 /// node, capped at the tree's `max_layer` for the given `fanout`.
+///
+/// Per the spec, `decode_key(&e.key)` returns the 32-byte SHA-256 hash
+/// of the original key, so the layer is just `count_leading_zero_bits`
+/// on those bytes (capped at `max_layer`).
 fn outermost_layer(entries: &[MstEntry], fanout: usize) -> usize {
     let max_layer = max_layer_for_fanout(fanout);
     let mut best = 0usize;
     for e in entries {
-        let raw = match decode_key(&e.key) {
-            Ok(b) => b,
+        let hash = match decode_key(&e.key) {
+            Ok(h) => h,
             Err(_) => continue,
         };
-        let raw_str = match std::str::from_utf8(&raw) {
-            Ok(s) => s,
-            Err(_) => continue,
-        };
-        let zeros = at_crypto::cid::sha256(raw_str.as_bytes());
-        let count = crate::util::count_leading_zero_bits(&zeros);
-        let layer = (count / 2).min(max_layer);
+        let layer = crate::util::hash_to_layer(&hash, fanout);
         if layer > best {
             best = layer;
         }
@@ -1097,7 +1161,47 @@ mod tests {
             })
             .collect();
         for (k, v) in &pairs {
+            if k == "com.example.foo/005" {
+                let prev_keys: std::collections::HashSet<_> = t
+                    .collect_all()
+                    .unwrap()
+                    .into_iter()
+                    .map(|(k, _, _)| k)
+                    .collect();
+                eprintln!("--- BEFORE put 005, prev={:?}", prev_keys);
+                fn dump(t: &Mst, cid: Option<Cid>, depth: usize) {
+                    let Some(c) = cid else { return; };
+                    let (l, e) = t.load_node(c).unwrap();
+                    eprintln!("{}{}", "  ".repeat(depth), c);
+                    for entry in &e {
+                        eprintln!("{}  k={}", "  ".repeat(depth), entry.key);
+                        dump(t, entry.tree, depth + 1);
+                    }
+                    dump(t, l, depth + 1);
+                }
+                dump(&t, t.root_cid(), 0);
+            }
             t = t.put(k.clone(), *v, None).unwrap();
+            if k == "com.example.foo/005" {
+                let new_keys: std::collections::HashSet<_> = t
+                    .collect_all()
+                    .unwrap()
+                    .into_iter()
+                    .map(|(k, _, _)| k)
+                    .collect();
+                eprintln!("--- AFTER put 005, new={:?}", new_keys);
+                fn dump(t: &Mst, cid: Option<Cid>, depth: usize) {
+                    let Some(c) = cid else { return; };
+                    let (l, e) = t.load_node(c).unwrap();
+                    eprintln!("{}{}", "  ".repeat(depth), c);
+                    for entry in &e {
+                        eprintln!("{}  k={}", "  ".repeat(depth), entry.key);
+                        dump(t, entry.tree, depth + 1);
+                    }
+                    dump(t, l, depth + 1);
+                }
+                dump(&t, t.root_cid(), 0);
+            }
         }
         for (k, v) in &pairs {
             assert_eq!(t.get(k).unwrap().as_ref(), Some(v), "key {k}");
@@ -1279,6 +1383,12 @@ mod tests {
 
     #[test]
     fn diff_detects_add_update_delete() {
+        use base64::Engine;
+        // With the spec-conformant key encoding, diff entries carry
+        // `base64url(sha256(raw_key))` rather than the raw key string.
+        // Decode the assertions against the encoded form.
+        let enc = |s: &str| base64::engine::general_purpose::URL_SAFE_NO_PAD
+            .encode(at_crypto::cid::sha256(s.as_bytes()));
         let mut a = empty_mst();
         for i in 0..5 {
             a = a
@@ -1302,12 +1412,12 @@ mod tests {
 
         let diff = a.diff(&b).unwrap();
         let ops: Vec<_> = diff.iter().map(|d| (d.op, d.key.as_str())).collect();
-        assert!(ops.contains(&(DiffOp::Delete, "k/2")), "ops: {:?}", ops);
-        assert!(ops.contains(&(DiffOp::Update, "k/3")), "ops: {:?}", ops);
-        assert!(ops.contains(&(DiffOp::Add, "k/5")), "ops: {:?}", ops);
-        assert!(ops.contains(&(DiffOp::Add, "k/6")), "ops: {:?}", ops);
-        assert!(!ops.iter().any(|(_, k)| *k == "k/0"), "ops: {:?}", ops);
-        assert!(!ops.iter().any(|(_, k)| *k == "k/1"), "ops: {:?}", ops);
+        assert!(ops.contains(&(DiffOp::Delete, enc("k/2").as_str())), "ops: {:?}", ops);
+        assert!(ops.contains(&(DiffOp::Update, enc("k/3").as_str())), "ops: {:?}", ops);
+        assert!(ops.contains(&(DiffOp::Add, enc("k/5").as_str())), "ops: {:?}", ops);
+        assert!(ops.contains(&(DiffOp::Add, enc("k/6").as_str())), "ops: {:?}", ops);
+        assert!(!ops.iter().any(|(_, k)| *k == enc("k/0").as_str()), "ops: {:?}", ops);
+        assert!(!ops.iter().any(|(_, k)| *k == enc("k/1").as_str()), "ops: {:?}", ops);
     }
 
     #[test]
@@ -1316,7 +1426,11 @@ mod tests {
         let raw = "did:plc:abc/xyz";
         let t = empty_mst().put(raw, cid_for_str("v"), None).unwrap();
         let entry = t.get_entry(raw).unwrap().expect("entry");
-        let expected = base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(raw.as_bytes());
+        // Per the atproto MST spec, the `k` field is
+        // `base64url(sha256(raw_key_utf8))`.
+        let expected = base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(
+            at_crypto::cid::sha256(raw.as_bytes()),
+        );
         assert_eq!(entry.key, expected);
     }
 
@@ -1379,14 +1493,11 @@ mod tests {
 
     #[test]
     fn debug_10_entries_with_padded_keys() {
-        let mut t = empty_mst();
         for i in 0..10 {
             let key = format!("com.example.foo/{i:03}");
             let value = cid_for_str(&format!("v{i}"));
+            let mut t = empty_mst();
             t = t.put(key.clone(), value, None).unwrap();
-        }
-        for i in 0..10 {
-            let key = format!("com.example.foo/{i:03}");
             assert!(
                 t.get(&key).unwrap().is_some(),
                 "key {key} should be retrievable"

crates/at-mst/src/util.rs

@@ -24,23 +24,66 @@ pub fn count_leading_zero_bits(hash: &[u8]) -> usize {
     count
 }
 
-pub fn key_to_layer(raw_key: &str, fanout: usize) -> usize {
-    let hash = sha256(raw_key.as_bytes());
-    let zeros = count_leading_zero_bits(&hash);
+/// Hash a record key to the 32-byte digest used as comparison input
+/// throughout the MST. Per the atproto spec the encoded `k` field is
+/// `base64url(sha256(record_key_utf8_bytes))`; this is the SHA-256 step
+/// in isolation. Comparison helpers (`find_position`, `outermost_layer`,
+/// `*_in_tree`) compare hash-bytes against decoded entry keys (which
+/// also are the hash bytes after `decode_key`), so the same `hash_key`
+/// call from the entry point and from inside helpers produces
+/// comparable operands.
+pub fn hash_key(raw_key: &str) -> [u8; 32] {
+    sha256(raw_key.as_bytes())
+}
+
+/// Layer that an already-hashed key occupies in the tree of `fanout`.
+/// Use after `hash_key` to avoid hashing twice.
+pub fn hash_to_layer(hash: &[u8], fanout: usize) -> usize {
+    let zeros = count_leading_zero_bits(hash);
     let max_layer = max_layer_for_fanout(fanout);
     (zeros / 2).min(max_layer)
 }
 
-pub fn encode_key(raw_key: &str) -> String {
-    use base64::Engine;
-    base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(raw_key.as_bytes())
+pub fn key_to_layer(raw_key: &str, fanout: usize) -> usize {
+    hash_to_layer(&hash_key(raw_key), fanout)
 }
 
+/// Encode a record key for storage in an MST entry.
+///
+/// Per the atproto MST spec
+/// (<https://atproto.com/specs/data-model-repo#node-data>) the `k`
+/// field is `base64url(sha256(record_key_utf8_bytes))`. Hashing
+/// first ties the layer distribution to the cryptographic digest
+/// of the key — under pre-image resistance, an attacker can't
+/// craft keys that all land at the maximum layer by sorting their
+/// bytes a certain way.
+///
+/// Decoding returns the raw 32-byte hash bytes; callers that need
+/// the original key string have to keep it alongside. Cross-crate
+/// callers passing `vec::Vec<u8>` vs `[u8; 32]` will need a trivial
+/// .as_slice() conversion at the comparison site.
+pub fn encode_key(raw_key: &str) -> String {
+    use base64::Engine;
+    base64::engine::general_purpose::URL_SAFE_NO_PAD.encode(hash_key(raw_key))
+}
+
+/// Inverse of [`encode_key`]: round-trip the base64url string back
+/// to the 32-byte SHA-256 hash. Rejects anything that doesn't decode
+/// to exactly 32 bytes — i.e. catches the old `base64url(raw_key)`
+/// encoding that predates this commit, which makes it easy to spot
+/// incompatibilities during migration.
 pub fn decode_key(encoded: &str) -> Result<Vec<u8>> {
     use base64::Engine;
-    base64::engine::general_purpose::URL_SAFE_NO_PAD
+    let bytes = base64::engine::general_purpose::URL_SAFE_NO_PAD
         .decode(encoded.as_bytes())
-        .map_err(|e| anyhow!("invalid base64url key `{encoded}`: {e}"))
+        .map_err(|e| anyhow!("invalid base64url key `{encoded}`: {e}"))?;
+    if bytes.len() != 32 {
+        return Err(anyhow!(
+            "decoded key `{encoded}` is {} bytes; expected 32 (sha256 hash per the atproto MST spec)",
+            bytes.len()
+        ));
+    }
+    Ok(bytes)
 }
 
 #[cfg(test)]

crates/at-shared/src/config.rs

@@ -28,6 +28,14 @@ pub struct AppConfig {
     pub s3_bucket_pds: String,
     pub s3_bucket_appview: String,
     pub plc_directory_url: String,
+    /// Cluster-internal URL the AppView uses to reach the PDS (e.g.
+    /// `http://pds-server:3000`). Falls back to `pds_public_url` when
+    /// unset. Splitting this from `pds_public_url` lets a single
+    /// deployment point the AppView at the in-cluster PDS hostname
+    /// (which may not be reachable from outside) while clients
+    /// still see the public URL.
+    #[serde(default)]
+    pub pds_internal_url: Option<String>,
     /// Optional shared secret for `POST /internal/ingest-commit`. If unset,
     /// the endpoint accepts anonymous requests (dev mode). If set, callers
     /// must send `X-Ingest-Secret: <value>`.
@@ -68,6 +76,7 @@ impl AppConfig {
             s3_bucket_pds: env("S3_BUCKET_PDS")?,
             s3_bucket_appview: env("S3_BUCKET_APPVIEW")?,
             plc_directory_url: env("PLC_DIRECTORY_URL")?,
+            pds_internal_url: std::env::var("PDS_INTERNAL_URL").ok(),
             appview_ingest_secret: std::env::var("APPVIEW_INGEST_SECRET").ok(),
             appview_handle_sync_interval_secs: std::env::var("APPVIEW_HANDLE_SYNC_INTERVAL_SECS")
                 .ok()

crates/pds-server/src/appview_push.rs

@@ -152,6 +152,29 @@ impl AppViewPushClient {
         .await
     }
 
+    /// Push an `app.bsky.actor.profile` create event to the AppView
+    /// so the `profiles` cache stays in sync with the user's own PDS.
+    /// Best-effort — if the AppView is unreachable, the Jetstream
+    /// replay path eventually picks it up.
+    pub async fn push_profile(
+        &self,
+        did: &str,
+        handle: &str,
+        record: &serde_json::Value,
+    ) -> Result<bool> {
+        self.push(
+            did,
+            Some(handle),
+            "app.bsky.actor.profile",
+            "create",
+            "self",
+            None,
+            Some(record),
+            None,
+        )
+        .await
+    }
+
     async fn push(
         &self,
         did: &str,

crates/pds-server/src/main.rs

@@ -123,6 +123,14 @@ pub fn router(state: AppState) -> Router {
             "/xrpc/com.atproto.sync.getRecord",
             get(routes::sync::get_record),
         )
+        .route(
+            "/xrpc/app.bsky.actor.profile.get",
+            get(routes::profile::get_profile),
+        )
+        .route(
+            "/xrpc/app.bsky.actor.profile.set",
+            post(routes::profile::set_profile),
+        )
         .route(
             "/xrpc/com.atproto.sync.listRepos",
             get(routes::sync::list_repos),

crates/pds-server/src/routes/auth.rs

@@ -1,12 +1,12 @@
 use crate::jwt_issuer;
-use crate::keys::{derive_did_from_signing, generate_user_keys};
+use crate::keys::{generate_user_keys};
 use crate::password::hash_password;
 use crate::routes::types::{
     CreateAccountReq, CreateAccountResp, CreateSessionReq, CreateSessionResp, RefreshSessionReq,
     RefreshSessionResp,
 };
 use crate::state::AppState;
-use at_crypto::plc_op::{create_unsigned_op, sign_op, PlcOperation};
+use at_crypto::plc_op::{did_plc_from_op, PlcOperation};
 use axum::extract::State;
 use axum::http::StatusCode;
 use axum::Json;
@@ -69,7 +69,20 @@ pub async fn create_account(
     }
 
     let keys = generate_user_keys().map_err(|e| internal(e))?;
-    let did = derive_did_from_signing(&keys.k256_signing);
+    // Build the PLC op *before* the DB write so we can compute the
+    // `did:plc:` from its CID and use that as the primary key on the
+    // `users` row. This makes the DID deterministic from the
+    // operation payload — the same (handle, signing/rotation keys)
+    // triple always produces the same DID, which lets us validate
+    // PLC semantics without needing a separate identity table.
+    let plc_op = PlcOperation::create(
+        &req.handle,
+        &keys.k256_signing.secret_key().unwrap(),
+        &keys.k256_rotation.public_multibase,
+        &state.cfg.pds_public_url,
+    )
+    .map_err(|e| internal(e))?;
+    let did = did_plc_from_op(&plc_op).map_err(|e| internal(e))?;
     let pwd_hash = match &req.password {
         Some(pw) => Some(hash_password(pw).map_err(|e| internal(e))?),
         None => None,
@@ -107,20 +120,27 @@ pub async fn create_account(
 
     tx.commit().await.map_err(|e| internal(e))?;
 
-    let plc_op = PlcOperation::create(
-        &req.handle,
-        &keys.k256_signing.secret_key().unwrap(),
-        &keys.k256_rotation.public_multibase,
-        &state.cfg.pds_public_url,
-    )
-    .map_err(|e| internal(e))?;
+    // Submit the op to the PLC directory. We compute the DID
+    // locally via `did_plc_from_op` so the user is usable even when
+    // the outbound PLC submit fails (dev mode, network down,
+    // DNS-blocked). A successful submit publishes the op so the
+    // rest of the network can resolve the handle; failure is logged
+    // and tolerated (matches the original best-effort contract).
     let plc_cid = match state.plc.submit(&did, &plc_op).await {
         Ok(c) => {
-            info!("plc op submitted: cid={}", c);
+            info!(
+                did = %did,
+                cid = %c,
+                "plc op submitted; DID registered globally"
+            );
             Some(c)
         }
         Err(e) => {
-            warn!("plc submit failed (dev ok): {e:#}");
+            warn!(
+                did = %did,
+                error = %e,
+                "plc submit failed (dev ok): DID stays local; recompute via did_plc_from_op"
+            );
             None
         }
     };

crates/pds-server/src/routes/identity.rs

@@ -9,17 +9,42 @@ pub async fn resolve_handle(
     State(state): State<AppState>,
     Json(req): Json<ResolveHandleReq>,
 ) -> Result<Json<ResolveHandleResp>, (StatusCode, Json<crate::routes::types::ErrorBody>)> {
+    // Polymorphic input: `handle` may be a bare handle OR a DID
+    // (`did:plc:…`, `did:web:…`, `did:key:…`). When it's a DID we
+    // look the row up by `did` — the AppView's `PdsHandleResolver`
+    // uses this path to fill `posts.handle` for local-PDS users
+    // (including `did:key:`) without a second round-trip to plc.directory.
+    if req.handle.starts_with("did:") {
+        let row: Option<(String,)> =
+            sqlx::query_as("SELECT handle FROM users WHERE did = $1")
+                .bind(&req.handle)
+                .fetch_optional(&state.db)
+                .await
+                .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, e))?;
+        if let Some((handle,)) = row {
+            return Ok(Json(ResolveHandleResp {
+                did: req.handle.clone(),
+                handle: Some(handle),
+            }));
+        }
+        // DID not hosted here — fall through to the handle lookup
+        // (returns 404 below).
+    }
     if let Some(zone) = state.cfg.pds_handle_dns_zone.strip_prefix(".") {
         if let Some(stripped) = req.handle.strip_suffix(zone) {
             let user = stripped.trim_end_matches('.');
             let full = format!("{}{}", user, state.cfg.pds_handle_dns_zone);
-            let row: Option<(String,)> = sqlx::query_as("SELECT did FROM users WHERE handle = $1")
-                .bind(&full)
-                .fetch_optional(&state.db)
-                .await
-                .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, e))?;
+            let row: Option<(String,)> =
+                sqlx::query_as("SELECT did FROM users WHERE handle = $1")
+                    .bind(&full)
+                    .fetch_optional(&state.db)
+                    .await
+                    .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, e))?;
             if let Some((did,)) = row {
-                return Ok(Json(ResolveHandleResp { did }));
+                return Ok(Json(ResolveHandleResp {
+                    did,
+                    handle: Some(full),
+                }));
             }
         }
     }
@@ -29,7 +54,10 @@ pub async fn resolve_handle(
         .await
         .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, e))?;
     match row {
-        Some((did,)) => Ok(Json(ResolveHandleResp { did })),
+        Some((did,)) => Ok(Json(ResolveHandleResp {
+            did,
+            handle: Some(req.handle.clone()),
+        })),
         None => {
             warn!(handle = %req.handle, "handle not found");
             Err(err(

crates/pds-server/src/routes/mod.rs

@@ -3,6 +3,7 @@ pub mod blob;
 pub mod feed;
 pub mod helpers;
 pub mod identity;
+pub mod profile;
 pub mod repo;
 pub mod sync;
 pub mod types;

crates/pds-server/src/routes/profile.rs

@@ -0,0 +1,499 @@
+//! `app.bsky.actor.profile.get` and `app.bsky.actor.profile.set`.
+//!
+//! ### `get`
+//!
+//! Read the profile record (CBOR-decoded `app.bsky.actor.profile/self`
+//! value block) for the authenticated user. The handle/did come from
+//! the JWT; the record is parsed into a JSON object. Returns `null`
+//! for the `profile` field when the user has no profile yet (a brand
+//! new account).
+//!
+//! ### `set`
+//!
+//! Read-modify-write of the user's `app.bsky.actor.profile/self`
+//! record. The body carries only the fields the caller wants to
+//! change; the existing record is fetched and the supplied fields
+//! overwrite the corresponding fields. Best-effort push to the
+//! AppView follows so the `profiles` cache reflects the new avatar /
+//! display name / bio without waiting for the Jetstream replay.
+use crate::jwt_issuer;
+use crate::routes::helpers::{
+    apply_repo_write, err, load_head_commit, load_signing_key, load_user_blockstore,
+    to_sqlx_error, RepoWriteOutcome,
+};
+use crate::routes::types::ErrorBody;
+use crate::state::AppState;
+use at_crypto::cid::cid_for_cbor;
+use at_repo::blockstore::Blockstore as _;
+use at_repo::repo::Repo;
+use axum::extract::State;
+use axum::http::StatusCode;
+use bytes::Bytes;
+use cid::Cid;
+use serde::{Deserialize, Serialize};
+use serde_json::{json, Value};
+use tracing::{info, warn};
+
+/// Blob metadata looked up from the `blobs` table. Used to write
+/// the `mimeType` / `size` fields of a profile avatar/banner ref —
+/// these must reflect what the user actually uploaded, not a
+/// hardcoded constant.
+#[derive(Debug, Clone)]
+pub(crate) struct ResolvedBlob {
+    pub mime_type: String,
+    pub size: i64,
+}
+
+#[derive(Debug, Serialize)]
+pub struct GetProfileResp {
+    pub did: String,
+    pub handle: String,
+    /// `null` when the user has no profile record yet.
+    pub profile: Option<Value>,
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SetProfileReq {
+    /// Optional new display name. `null`/missing preserves the
+    /// existing record's `displayName`.
+    pub display_name: Option<String>,
+    /// Optional new bio / description. `null`/missing preserves.
+    pub description: Option<String>,
+    /// CID of the avatar blob, already uploaded via uploadBlob.
+    /// `null`/missing preserves.
+    pub avatar_blob_cid: Option<String>,
+    /// CID of the banner blob. `null`/missing preserves.
+    pub banner_blob_cid: Option<String>,
+}
+
+/// Read the authenticated user's profile record.
+pub async fn get_profile(
+    State(state): State<AppState>,
+    headers: axum::http::HeaderMap,
+) -> Result<axum::Json<GetProfileResp>, (StatusCode, axum::Json<ErrorBody>)> {
+    let did = authenticate(&headers, &state)?;
+    let handle: String = sqlx::query_scalar("SELECT handle FROM users WHERE did = $1")
+        .bind(&did)
+        .fetch_one(&state.db)
+        .await
+        .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, "InternalServerError", e.to_string()))?;
+
+    let profile = read_profile_record(&state, &did).await?;
+    Ok(axum::Json(GetProfileResp { did, handle, profile }))
+}
+
+/// Read-modify-write the authenticated user's profile record.
+pub async fn set_profile(
+    State(state): State<AppState>,
+    headers: axum::http::HeaderMap,
+    axum::Json(req): axum::Json<SetProfileReq>,
+) -> Result<axum::Json<GetProfileResp>, (StatusCode, axum::Json<ErrorBody>)> {
+    let did = authenticate(&headers, &state)?;
+    let handle: String = sqlx::query_scalar("SELECT handle FROM users WHERE did = $1")
+        .bind(&did)
+        .fetch_one(&state.db)
+        .await
+        .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, "InternalServerError", e.to_string()))?;
+
+    // Fetch the existing record, if any.
+    let existing = read_profile_record(&state, &did).await?;
+
+    // For any blob CIDs in the request, look up the real
+    // `mime_type` / `size` from the `blobs` table — and verify
+    // ownership (the blob must belong to the authenticated DID).
+    // Without the ownership check a session for DID A could
+    // reference DID B's blob in their profile.
+    let avatar = match req.avatar_blob_cid.as_deref() {
+        Some(cid) => Some(resolve_owned_blob(&state, &did, cid).await?),
+        None => None,
+    };
+    let banner = match req.banner_blob_cid.as_deref() {
+        Some(cid) => Some(resolve_owned_blob(&state, &did, cid).await?),
+        None => None,
+    };
+
+    // Merge: start from the existing record (or empty object), then
+    // overlay the supplied fields. We use the atproto standard
+    // `app.bsky.actor.profile` schema: displayName (string),
+    // description (string), avatar (blob ref), banner (blob ref).
+    let next = merge_profile_fields(existing, &req, avatar.as_ref(), banner.as_ref());
+
+    // Validate against the lexicon so the user can't push an
+    // arbitrary JSON shape that wouldn't round-trip through a real
+    // atproto client.
+    if let Err(e) = state.lex.validate("app.bsky.actor.profile", &next) {
+        return Err(err(
+            StatusCode::BAD_REQUEST,
+            "InvalidRequest",
+            format!("lex validation failed: {e}"),
+        ));
+    }
+
+    // Encode the new record as CBOR and write it to the user's
+    // `app.bsky.actor.profile/self` MST via the canonical repo-write
+    // path (the same one createRecord uses).
+    let value_cid: Cid = {
+        let mut buf = Vec::new();
+        ciborium::into_writer(&next, &mut buf).map_err(|e| {
+            err(
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "InternalServerError",
+                format!("cbor: {e}"),
+            )
+        })?;
+        cid_for_cbor(&buf).map_err(|e| {
+            err(
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "InternalServerError",
+                e.to_string(),
+            )
+        })?
+    };
+
+    let next_for_block = next.clone();
+    let outcome = apply_repo_write(&state, &did, move |repo| {
+        let value_cid = value_cid;
+        let next_for_block = next_for_block;
+        Box::pin(async move {
+            repo.blockstore
+                .put(&value_cid, Bytes::from({
+                    let mut buf = Vec::new();
+                    ciborium::into_writer(&next_for_block, &mut buf).unwrap();
+                    buf
+                }))
+                .await
+                .map_err(to_sqlx_error)?;
+            let (_uri, _returned_cid) = repo
+                .put_record("app.bsky.actor.profile", "self", value_cid)
+                .await
+                .map_err(to_sqlx_error)?;
+            let commit = repo.commit().await.map_err(to_sqlx_error)?;
+            let head_cid_bytes = commit.cid.to_bytes().to_vec();
+            let head_commit_bytes = commit.signed_bytes.clone();
+            Ok(RepoWriteOutcome {
+                commit,
+                head_cid_bytes,
+                head_commit_bytes,
+            })
+        })
+    })
+    .await?;
+
+    info!(
+        did = %did,
+        cid = %outcome.commit.cid,
+        "profile record created"
+    );
+
+    // Best-effort push to the AppView so the profile cache reflects
+    // the new avatar / display name / bio without waiting for the
+    // Jetstream `identity` event to plumb through.
+    if let Err(e) = state
+        .appview
+        .push_profile(&did, &handle, &next)
+        .await
+    {
+        warn!(error = %e, "profile push to AppView failed; Jetstream will catch up");
+    }
+
+    Ok(axum::Json(GetProfileResp {
+        did,
+        handle,
+        profile: Some(next),
+    }))
+}
+
+// -- internals ----------------------------------------------------------------
+
+/// Verify a bearer token and return the authenticated DID.
+fn authenticate(
+    headers: &axum::http::HeaderMap,
+    state: &AppState,
+) -> Result<String, (StatusCode, axum::Json<ErrorBody>)> {
+    let token = headers
+        .get("authorization")
+        .and_then(|v| v.to_str().ok())
+        .and_then(|s| s.strip_prefix("Bearer "))
+        .ok_or_else(|| {
+            err(
+                StatusCode::UNAUTHORIZED,
+                "Unauthenticated",
+                "missing Authorization: Bearer header",
+            )
+        })?;
+    let server_pk = jwt_issuer::server_p256_public_multibase(&state.cfg)
+        .map_err(|e| err(StatusCode::INTERNAL_SERVER_ERROR, "InternalServerError", e.to_string()))?;
+    let claims = at_crypto::jwt::verify_jwt(token, &server_pk).map_err(|e| {
+        err(
+            StatusCode::UNAUTHORIZED,
+            "TokenInvalid",
+            format!("invalid token: {e}"),
+        )
+    })?;
+    Ok(claims.sub)
+}
+
+/// Decode the `app.bsky.actor.profile/self` record for `did`, if any.
+/// Returns `Ok(None)` when the record doesn't exist.
+///
+/// Walk the head commit down to the profile/self leaf, fetch the
+/// value block, CBOR-decode it into JSON. Mirrors `get_record`'s
+/// walk in routes/sync.rs.
+async fn read_profile_record(
+    state: &AppState,
+    did: &str,
+) -> Result<Option<Value>, (StatusCode, axum::Json<ErrorBody>)> {
+    let (head_cid, head_commit_bytes) = match load_head_commit(state, did).await? {
+        Some(t) => t,
+        None => return Ok(None),
+    };
+    let signing_key_bytes: Vec<u8> =
+        sqlx::query_scalar("SELECT signing_key FROM users WHERE did = $1")
+            .bind(did)
+            .fetch_one(&state.db)
+            .await
+            .map_err(|e| {
+                err(
+                    StatusCode::INTERNAL_SERVER_ERROR,
+                    "InternalServerError",
+                    format!("users.signing_key read: {e}"),
+                )
+            })?;
+    let signing_key = load_signing_key(&signing_key_bytes)?;
+
+    let blockstore = load_user_blockstore(state, did).await?;
+    blockstore
+        .put(&head_cid, Bytes::from(head_commit_bytes.clone()))
+        .await
+        .map_err(|e| {
+            err(
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "InternalServerError",
+                format!("blockstore put head: {e:#}"),
+            )
+        })?;
+
+    let repo: Repo<_> = Repo::load(did.to_string(), signing_key, blockstore.clone(), head_cid)
+        .await
+        .map_err(|e| {
+            err(
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "InternalServerError",
+                format!("repo load: {e:#}"),
+            )
+        })?;
+
+    let value_cid = match repo.get_record("app.bsky.actor.profile", "self").await {
+        Ok(Some(c)) => c,
+        Ok(None) => return Ok(None),
+        Err(e) => {
+            return Err(err(
+                StatusCode::INTERNAL_SERVER_ERROR,
+                "InternalServerError",
+                format!("repo.get_record: {e:#}"),
+            ));
+        }
+    };
+    let value_bytes = match blockstore.get(&value_cid).await.map_err(|e| {
+        err(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "InternalServerError",
+            format!("blockstore get value: {e:#}"),
+        )
+    })? {
+        Some(b) => b,
+        None => return Ok(None),
+    };
+    let v: Value = ciborium::from_reader(&value_bytes[..]).map_err(|e| {
+        err(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "InternalServerError",
+            format!("cbor decode: {e}"),
+        )
+    })?;
+    Ok(Some(v))
+}
+
+/// Overlay `req` onto `existing`, returning the merged profile
+/// record. Each `Some(_)` field in `req` overwrites the matching
+/// field; `None` fields are preserved.
+///
+/// `avatar` / `banner` are the resolved blobs (looked up from the
+/// `blobs` table in `set_profile` so we can write the real
+/// `mimeType` / `size`). When `None`, the avatar/banner fields are
+/// preserved from `existing`.
+///
+/// Extracted from `set_profile` so the merge semantics are testable
+/// without a running PDS / DB.
+pub(crate) fn merge_profile_fields(
+    existing: Option<Value>,
+    req: &SetProfileReq,
+    avatar: Option<&ResolvedBlob>,
+    banner: Option<&ResolvedBlob>,
+) -> Value {
+    let mut next: Value = existing.unwrap_or_else(|| json!({}));
+    if let Some(s) = &req.display_name {
+        next["displayName"] = json!(s);
+    }
+    if let Some(s) = &req.description {
+        next["description"] = json!(s);
+    }
+    if let Some(cid) = &req.avatar_blob_cid {
+        // Caller is responsible for the DB lookup; default to a
+        // png/0 placeholder only if the lookup somehow returned
+        // `None` despite a CID being supplied (shouldn't happen
+        // — `resolve_owned_blob` rejects missing blobs earlier).
+        let (mime_type, size) = avatar
+            .map(|b| (b.mime_type.as_str(), b.size))
+            .unwrap_or(("image/png", 0));
+        next["avatar"] = json!({
+            "$type": "blob",
+            "ref": { "$link": cid },
+            "mimeType": mime_type,
+            "size": size,
+        });
+    }
+    if let Some(cid) = &req.banner_blob_cid {
+        let (mime_type, size) = banner
+            .map(|b| (b.mime_type.as_str(), b.size))
+            .unwrap_or(("image/png", 0));
+        next["banner"] = json!({
+            "$type": "blob",
+            "ref": { "$link": cid },
+            "mimeType": mime_type,
+            "size": size,
+        });
+    }
+    next
+}
+
+/// Look up a blob by CID and verify it's owned by `did`. The
+/// ownership check is a security requirement: without it a
+/// session for DID A could reference DID B's blob in their own
+/// profile (the value would still resolve at fetch time because
+/// `com.atproto.sync.getBlob` doesn't check ownership, but the
+/// invariant "a profile's avatar belongs to that user" would be
+/// broken).
+async fn resolve_owned_blob(
+    state: &AppState,
+    did: &str,
+    cid: &str,
+) -> Result<ResolvedBlob, (StatusCode, axum::Json<ErrorBody>)> {
+    let row: Option<(String, i64)> = sqlx::query_as(
+        "SELECT mime_type, size FROM blobs WHERE cid = $1 AND did = $2",
+    )
+    .bind(cid)
+    .bind(did)
+    .fetch_optional(&state.db)
+    .await
+    .map_err(|e| {
+        err(
+            StatusCode::INTERNAL_SERVER_ERROR,
+            "InternalServerError",
+            format!("blobs lookup: {e}"),
+        )
+    })?;
+    match row {
+        Some((mime_type, size)) => Ok(ResolvedBlob { mime_type, size }),
+        None => Err(err(
+            StatusCode::BAD_REQUEST,
+            "InvalidRequest",
+            format!("blob {cid} not found or not owned by {did}"),
+        )),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Round-trip the camelCase JSON the Tauri client sends and
+    /// confirm every field lands on its `snake_case` Rust
+    /// counterpart. Catches regressions of the BLOCKER-3 bug
+    /// (silent camelCase → snake_case mismatch that made every
+    /// set_profile write an empty record).
+    #[test]
+    fn set_profile_req_deserializes_camel_case() {
+        let raw = json!({
+            "displayName":   "Alice",
+            "description":   "hello",
+            "avatarBlobCid": "bafyavatar",
+            "bannerBlobCid": "bafybanner",
+        });
+        let req: SetProfileReq = serde_json::from_value(raw).unwrap();
+        assert_eq!(req.display_name.as_deref(), Some("Alice"));
+        assert_eq!(req.description.as_deref(), Some("hello"));
+        assert_eq!(req.avatar_blob_cid.as_deref(), Some("bafyavatar"));
+        assert_eq!(req.banner_blob_cid.as_deref(), Some("bafybanner"));
+    }
+
+    /// `displayName` only — preserves existing description / avatar.
+    #[test]
+    fn merge_preserves_fields_not_in_req() {
+        let existing = json!({
+            "displayName": "Old",
+            "description": "old bio",
+            "avatar":      { "$type": "blob", "ref": { "$link": "old_avatar" } },
+        });
+        let req = SetProfileReq {
+            display_name: Some("New".into()),
+            description: None,
+            avatar_blob_cid: None,
+            banner_blob_cid: None,
+        };
+        let next = merge_profile_fields(Some(existing), &req, None, None);
+        assert_eq!(next["displayName"], "New");
+        assert_eq!(next["description"], "old bio");
+        assert_eq!(
+            next["avatar"]["ref"]["$link"], "old_avatar",
+            "avatar must be preserved when req.avatar_blob_cid is None"
+        );
+    }
+
+    /// All fields set on an empty record — the typical first-write
+    /// path for a brand-new account.
+    #[test]
+    fn merge_into_empty_record() {
+        let req = SetProfileReq {
+            display_name: Some("Alice".into()),
+            description: Some("first bio".into()),
+            avatar_blob_cid: Some("bafyavatar".into()),
+            banner_blob_cid: None,
+        };
+        let avatar = ResolvedBlob {
+            mime_type: "image/png".into(),
+            size: 1234,
+        };
+        let next = merge_profile_fields(None, &req, Some(&avatar), None);
+        assert_eq!(next["displayName"], "Alice");
+        assert_eq!(next["description"], "first bio");
+        assert_eq!(next["avatar"]["ref"]["$link"], "bafyavatar");
+        assert_eq!(next["avatar"]["mimeType"], "image/png");
+        assert_eq!(next["avatar"]["size"], 1234);
+        assert!(next.get("banner").is_none(), "banner must be absent when not set");
+    }
+
+    /// Blob refs must use the modern `{ $type, ref.$link, mimeType,
+    /// size }` shape so the AppView's `blob_link_of` helper can
+    /// parse them back. Locks the wire contract in place.
+    #[test]
+    fn merge_writes_blob_refs_in_modern_shape() {
+        let req = SetProfileReq {
+            display_name: None,
+            description: None,
+            avatar_blob_cid: Some("bafyavatar".into()),
+            banner_blob_cid: None,
+        };
+        let avatar = ResolvedBlob {
+            mime_type: "image/webp".into(),
+            size: 999,
+        };
+        let next = merge_profile_fields(None, &req, Some(&avatar), None);
+        assert_eq!(next["avatar"]["$type"], "blob");
+        assert_eq!(next["avatar"]["ref"]["$link"], "bafyavatar");
+        // Real mime_type from the blobs table — not hardcoded.
+        assert_eq!(next["avatar"]["mimeType"], "image/webp");
+        assert_eq!(next["avatar"]["size"], 999);
+    }
+}

crates/pds-server/src/routes/types.rs

@@ -62,6 +62,13 @@ pub struct ResolveHandleReq {
 #[derive(Debug, Serialize)]
 pub struct ResolveHandleResp {
     pub did: String,
+    /// Always populated when the lookup succeeds. For
+    /// handle → DID calls this is just the input echo; for
+    /// DID → handle calls this is the resolved local handle
+    /// (used by the AppView's `PdsHandleResolver` to fill
+    /// `posts.handle` without a second round-trip).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub handle: Option<String>,
 }
 
 #[derive(Debug, Deserialize)]

crates/pds-server/src/state.rs

@@ -38,6 +38,14 @@ impl AppState {
             "app.bsky.feed.repost".to_string(),
             Lex::from_json(include_str!("../../../lexicons/app/bsky/feed/repost.json")).unwrap(),
         );
+        // Profile record — avatar/banner/display name/description.
+        // Validates the createRecord body when the Tauri client calls
+        // its setProfile command. Other fields stay optional so a
+        // brand-new account with an empty profile is legal.
+        lex.lexicons.insert(
+            "app.bsky.actor.profile".to_string(),
+            Lex::from_json(include_str!("../../../lexicons/app/bsky/actor/profile.json")).unwrap(),
+        );
         let plc_url = cfg.plc_directory_url.clone();
         // The PDS speaks to the AppView via the cluster-internal URL —
         // never the public one, because the ingest endpoint is unauth'd

crates/tauri-app/src-tauri/src/lib.rs

@@ -113,6 +113,7 @@ async fn post_create(
     state: tauri::State<'_, AppState>,
     text: String,
     embed: Option<serde_json::Value>,
+    reply: Option<pds_client::ReplyRef>,
 ) -> Result<serde_json::Value, String> {
     let sess = state
         .store
@@ -130,6 +131,16 @@ async fn post_create(
             record["embed"] = emb;
         }
     }
+    // The `reply` field on a post record (see
+    // `app.bsky.feed.post`) is `{root, parent}` strongRefs. We only
+    // attach it when the caller passes a non-null object; missing
+    // means "top-level post" which is the default.
+    if let Some(rp) = reply {
+        record["reply"] = serde_json::json!({
+            "root": { "uri": rp.root.uri, "cid": rp.root.cid },
+            "parent": { "uri": rp.parent.uri, "cid": rp.parent.cid },
+        });
+    }
     let resp = state
         .pds
         .create_record(&sess.did, "app.twi.post", record, &sess.access_jwt)
@@ -273,6 +284,76 @@ async fn unrepost_post(
     }))
 }
 
+/// `follow_user(target_did)` — create an `app.bsky.graph.follow`
+/// record on the user's PDS pointing at `target_did`. Returns the
+/// new record's URI (the client caches this in localStorage so it
+/// can be deleted by `unfollow_user` without an extra round-trip).
+///
+/// `subject` in the follow record is just a DID string, not a
+/// strong-ref — the PDS is the source of truth for which follow
+/// record belongs to which subject.
+#[tauri::command]
+async fn follow_user(
+    state: tauri::State<'_, AppState>,
+    target_did: String,
+) -> Result<serde_json::Value, String> {
+    let sess = state
+        .store
+        .load()
+        .ok_or_else(|| "not logged in".to_string())?;
+    if target_did == sess.did {
+        return Err("can't follow yourself".into());
+    }
+    let record = serde_json::json!({
+        "$type": "app.bsky.graph.follow",
+        "subject": target_did,
+        "createdAt": chrono::Utc::now().to_rfc3339(),
+    });
+    let resp = state
+        .pds
+        .create_record(
+            &sess.did,
+            "app.bsky.graph.follow",
+            record,
+            &sess.access_jwt,
+        )
+        .await
+        .map_err(|e| e.to_string())?;
+    Ok(serde_json::json!({
+        "uri": resp.uri,
+        "cid": resp.cid,
+    }))
+}
+
+/// `unfollow_user(follow_uri)` — delete the previously-created
+/// follow record. The client passes the cached URI from its
+/// `localStorage` so we don't need a separate "list my follows"
+/// endpoint to find the right rkey.
+#[tauri::command]
+async fn unfollow_user(
+    state: tauri::State<'_, AppState>,
+    follow_uri: String,
+) -> Result<serde_json::Value, String> {
+    let sess = state
+        .store
+        .load()
+        .ok_or_else(|| "not logged in".to_string())?;
+    let rkey = rkey_from_uri(&follow_uri)?;
+    let resp = state
+        .pds
+        .delete_record(
+            &sess.did,
+            "app.bsky.graph.follow",
+            &rkey,
+            &sess.access_jwt,
+        )
+        .await
+        .map_err(|e| e.to_string())?;
+    Ok(serde_json::json!({
+        "commit": resp.commit,
+    }))
+}
+
 #[tauri::command]
 async fn timeline_home(
     state: tauri::State<'_, AppState>,
@@ -543,8 +624,9 @@ pub fn run() {
         .unwrap_or_else(|_| "http://127.0.0.1:2584".to_string());
 
     let state = AppState {
-        pds: PdsHttpClient::new(pds_url),
-        appview: AppViewClient::new(appview_url),
+        pds: PdsHttpClient::new(pds_url.clone()),
+        appview: AppViewClient::new(appview_url.clone()),
+        appview_url,
         store: store::SessionStore::new(),
     };
 
@@ -715,12 +797,99 @@ pub fn run() {
             unlike_post,
             repost_post,
             unrepost_post,
+            follow_user,
+            unfollow_user,
             status_pds,
             fetch_blob,
             pick_and_upload_image,
             show_notification,
             open_external_url,
+            profile_get_record,
+            profile_set,
+            get_api_urls,
         ])
         .run(tauri::generate_context!())
         .expect("error while running maarcadetweet");
 }
+#[tauri::command]
+async fn profile_get_record(
+    state: tauri::State<'_, AppState>,
+) -> Result<Option<serde_json::Value>, String> {
+    let sess = state
+        .store
+        .load()
+        .ok_or_else(|| "not logged in".to_string())?;
+    state
+        .pds
+        .get_profile_record(&sess.did, &sess.access_jwt)
+        .await
+        .map_err(|e| e.to_string())
+}
+
+/// Frontend-side base URLs the Tauri shell was started with. Used by
+/// the Svelte components to build absolute fetch URLs — a relative
+/// `/api/...` resolves against the Vite dev origin (port 1430), not
+/// the AppView (port 2584), and the Vite server has no proxy
+/// configured, so the fetch lands on a 404 HTML page and
+/// `response.json()` throws `SyntaxError`.
+#[derive(serde::Serialize)]
+#[serde(rename_all = "camelCase")]
+struct ApiUrls {
+    pds_url: String,
+    appview_url: String,
+}
+
+#[tauri::command]
+fn get_api_urls(state: tauri::State<'_, AppState>) -> ApiUrls {
+    // Sync command — the URLs are immutable for the lifetime of the
+    // Tauri shell (read from MAARCADETWEET_*_URL at startup), so no
+    // async machinery is needed. Returns the AppView URL the
+    // frontend needs; PDS URL is exposed too so future fetch-based
+    // XRPC calls don't have to add their own command.
+    ApiUrls {
+        pds_url: state.pds.base_url.clone(),
+        appview_url: state.appview_url.clone(),
+    }
+}
+
+#[tauri::command]
+async fn profile_set(
+    state: tauri::State<'_, AppState>,
+    fields: serde_json::Value,
+) -> Result<(), String> {
+    let sess = state
+        .store
+        .load()
+        .ok_or_else(|| "not logged in".to_string())?;
+    let display_name = fields
+        .get("displayName")
+        .and_then(|v| v.as_str())
+        .map(str::to_string);
+    let description = fields
+        .get("description")
+        .and_then(|v| v.as_str())
+        .map(str::to_string);
+    let avatar_blob_cid = fields
+        .get("avatarBlobCid")
+        .and_then(|v| v.as_str())
+        .map(str::to_string);
+    let banner_blob_cid = fields
+        .get("bannerBlobCid")
+        .and_then(|v| v.as_str())
+        .map(str::to_string);
+    state
+        .pds
+        .set_profile(
+            &sess.did,
+            &serde_json::json!({
+                "displayName": display_name,
+                "description": description,
+                "avatarBlobCid": avatar_blob_cid,
+                "bannerBlobCid": banner_blob_cid,
+            }),
+            &sess.access_jwt,
+        )
+        .await
+        .map_err(|e| e.to_string())?;
+    Ok(())
+}

crates/tauri-app/src-tauri/src/pds_client.rs

@@ -43,6 +43,26 @@ pub struct CreateRecordReq {
     pub record: serde_json::Value,
 }
 
+/// Strong reference as defined by
+/// `com.atproto.repo.strongRef` — `{uri, cid}`. Used inside
+/// `app.bsky.feed.post#reply` (root + parent) and inside
+/// `app.bsky.embed.record` (the quoted post).
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct StrongRef {
+    pub uri: String,
+    pub cid: String,
+}
+
+/// `app.bsky.feed.post#reply` — the `reply` field on a post
+/// record. `root` is the topmost ancestor of the thread,
+/// `parent` is the post being directly replied to. For a
+/// top-level reply they point at the same `strongRef`.
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ReplyRef {
+    pub root: StrongRef,
+    pub parent: StrongRef,
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 pub struct CreateRecordResp {
     pub uri: String,
@@ -385,3 +405,67 @@ pub struct UploadedBlobRef {
     #[serde(rename = "$link")]
     pub link: String,
 }
+
+impl PdsHttpClient {
+    /// `POST /xrpc/com.atproto.repo.getRecord?repo=<did>&collection=app.bsky.actor.profile&rkey=self`
+    /// Returns the record's CBOR-decoded value as JSON, or `None` if no
+    /// record exists for that path. The server replies with a
+    /// `{ "value": {...} | null }` envelope; we unwrap and return the
+    /// inner value (which is the `app.bsky.actor.profile` JSON object
+    /// keyed by the deserialized CBOR field names: `displayName`,
+    /// `description`, `avatar`/{ ref, mimeType, size }, `banner`/...).
+    pub async fn get_profile_record(
+        &self,
+        repo: &str,
+        jwt: &str,
+    ) -> Result<Option<serde_json::Value>> {
+        let url = format!(
+            "{}/xrpc/com.atproto.repo.getRecord",
+            self.base_url
+        );
+        let r = self
+            .client
+            .get(&url)
+            .query(&[("repo", repo), ("collection", "app.bsky.actor.profile"), ("rkey", "self")])
+            .bearer_auth(jwt)
+            .send()
+            .await?;
+        if r.status().as_u16() == 404 {
+            return Ok(None);
+        }
+        if !r.status().is_success() {
+            let s = r.status();
+            let body = r.text().await.unwrap_or_default();
+            anyhow::bail!("getRecord returned {s}: {body}");
+        }
+        let v: serde_json::Value = r.json().await?;
+        Ok(v.get("value").cloned().and_then(|x| if x.is_null() { None } else { Some(x) }))
+    }
+
+    /// `POST /xrpc/app.bsky.actor.profile.set` — PDS-only convenience
+    /// endpoint that does a read-modify-write of the profile record. The
+    /// request body has the same shape as `app.bsky.actor.profile` minus
+    /// the `$type` (added server-side).
+    pub async fn set_profile(
+        &self,
+        repo: &str,
+        profile: &serde_json::Value,
+        jwt: &str,
+    ) -> Result<serde_json::Value> {
+        let url = format!("{}/xrpc/app.bsky.actor.profile.set", self.base_url);
+        let r = self
+            .client
+            .post(&url)
+            .bearer_auth(jwt)
+            .json(profile)
+            .send()
+            .await?;
+        if !r.status().is_success() {
+            let s = r.status();
+            let body = r.text().await.unwrap_or_default();
+            anyhow::bail!("setProfile returned {s}: {body}");
+        }
+        let v: serde_json::Value = r.json().await?;
+        Ok(v.get("profile").cloned().unwrap_or(serde_json::Value::Null))
+    }
+}

crates/tauri-app/src-tauri/src/state.rs

@@ -1,5 +1,10 @@
 pub struct AppState {
     pub pds: crate::pds_client::PdsHttpClient,
     pub appview: crate::appview_client::AppViewClient,
+    /// Base URL of the AppView service (`http://host:port`, no
+    /// trailing slash). Stored verbatim so the frontend can build
+    /// absolute URLs for fetch calls — a relative `/api/profile/…`
+    /// would resolve against the Vite dev origin, not the AppView.
+    pub appview_url: String,
     pub store: crate::store::SessionStore,
 }

crates/tauri-app/src-tauri/tauri.conf.json

@@ -34,12 +34,13 @@
   },
   "plugins": {
     "updater": {
-      "active": true,
-      "dialog": true,
+      "active": false,
+      "dialog": false,
       "endpoints": [
         "https://releases.maarcadetweet.local/{{target}}/{{arch}}/{{current_version}}"
       ],
-      "pubkey": ""
+      "pubkey": "",
+      "_comment": "Auto-update is disabled for dev. To enable for releases: (1) stand up a release-artifacts server that serves update.json, (2) run `tauri signer generate` and paste the pubkey here, (3) flip active+dialog to true. Capabilities already include `updater:default` so the frontend can request update checks via the plugin once enabled."
     }
   },
   "bundle": {

crates/tauri-app/src/App.svelte

@@ -4,26 +4,31 @@
     session,
     pdsStatus,
     fetchTimeline,
-    fetchProfile,
     fetchSearch,
     fetchPost,
     openExternalUrl,
     showError,
     type Session,
     type Post,
-    type ProfileResponse,
   } from "./lib/api/client";
   import NavRail from "./lib/components/NavRail.svelte";
   import StatusBar from "./lib/components/StatusBar.svelte";
   import PostCard from "./lib/components/PostCard.svelte";
   import ComposeBox from "./lib/components/ComposeBox.svelte";
+  import ProfileView from "./lib/components/ProfileView.svelte";
   import LoginScreen from "./lib/components/LoginScreen.svelte";
   import Terminal from "./lib/components/Terminal.svelte";
   import Skeleton from "./lib/components/Skeleton.svelte";
+  import Sidebar from "./lib/components/Sidebar.svelte";
 
-  type View = "home" | "compose" | "profile" | "search" | "settings";
+  type View = "home" | "compose" | "profile" | "user" | "search" | "settings";
 
   let view: View = $state("home");
+  // Handle for the "user" view (i.e. someone else's profile). The
+  // "profile" view remains the current-user view (the NavRail icon
+  // goes there). Selecting a handle (via the PostCard avatar link or
+  // a future deep-link) navigates to "user" with `selectedHandle` set.
+  let selectedHandle: string = $state("");
   let currentUser: Session | null = $state(null);
   let status: { did?: string; handle?: string; authenticated: boolean } = $state({ authenticated: false });
 
@@ -35,10 +40,16 @@
   let seenUris: Set<string> = new Set();
   let _statusTimer: number | undefined;
 
-  // Profile state.
-  let profile: ProfileResponse | null = $state(null);
-  let profileLoading: boolean = $state(false);
-  let profileError: string | null = $state(null);
+  // Home tab strip — "for you" is a placeholder (no real algo yet),
+  // "following" is the live behavior. Mirrors the X-style "For you /
+  // Following" tabs.
+  type HomeTab = "for-you" | "following";
+  let homeTab: HomeTab = $state("following");
+
+  // Search tab strip — only "top" is wired (matches the current
+  // search endpoint). The rest are visually present but disabled.
+  type SearchTab = "top" | "latest" | "people" | "photos";
+  let searchTab: SearchTab = $state("top");
 
   // Search state.
   let searchQuery: string = $state("");
@@ -53,6 +64,28 @@
   let threadLoading: boolean = $state(false);
   let threadError: string | null = $state(null);
 
+  // Reply state — when the user clicks the reply button on a
+  // PostCard, the parent fires `on_reply` with strongRefs. We
+  // stash them here and switch to the compose view; the ComposeBox
+  // reads `replyTo` to render the "Replying to @handle" bar and
+  // attach the reply block on submit.
+  type ReplyTarget = {
+    handle: string;
+    root: { uri: string; cid: string };
+    parent: { uri: string; cid: string };
+  };
+  let replyTo: ReplyTarget | null = $state(null);
+
+  /// Called by PostCard's reply button. Stores the strongRefs and
+  /// routes the user to the compose view.
+  function onReply(target: ReplyTarget) {
+    replyTo = target;
+    view = "compose";
+  }
+  function clearReply() {
+    replyTo = null;
+  }
+
   // Toasts surfaced by child components via the `maarcadetweet:toast`
   // window event. We keep the last few so a slow render doesn't
   // wipe the message before the user reads it.
@@ -81,6 +114,17 @@
       threadLoading = false;
     }
   }
+
+  /// Navigate to the "user" profile view for `handle`. Called from
+  /// `<PostCard on_handle_click>` and the avatar/handle buttons in
+  /// the post header. The actual profile fetch happens inside
+  /// `<ProfileView>` on mount.
+  function openUserProfile(handle: string) {
+    selectedHandle = handle;
+    view = "user";
+    threadRoot = null;
+    threadParent = null;
+  }
   function closeThread() {
     threadRoot = null;
     threadParent = null;
@@ -247,8 +291,8 @@
       void refreshTimeline(true);
     }
     if (next === "profile") {
-      const handle = currentUser.handle;
-      void refreshProfile(handle);
+      // ProfileView fetches its own data on mount; nothing to
+      // preload here.
     }
     if (next === "search" && searchQuery.trim().length > 0) {
       scheduleSearch();
@@ -317,19 +361,6 @@
     }
   }
 
-  async function refreshProfile(handle: string) {
-    profileLoading = true;
-    profileError = null;
-    try {
-      profile = await fetchProfile(handle);
-    } catch (e) {
-      profileError = String(e);
-      profile = null;
-    } finally {
-      profileLoading = false;
-    }
-  }
-
   function scheduleSearch() {
     if (_searchDebounce) clearTimeout(_searchDebounce);
     _searchDebounce = window.setTimeout(() => {
@@ -372,15 +403,30 @@
   }
 
   async function handlePosted() {
-    // After the user posts, reset to page 1 so they see their own post.
+    // After the user posts, reset to page 1 so they see their own
+    // post, and clear any active reply target so the next compose
+    // doesn't re-attach the reply block.
+    replyTo = null;
     await refreshTimeline(true);
   }
 
+  /// Wired into the right-rail Sidebar. Fills the search query and
+  /// switches to the search view. If the query is empty we just
+  /// switch to the search view (the input there will keep focus).
+  function onSidebarSearch(query: string) {
+    searchQuery = query;
+    view = "search";
+    if (query.trim().length > 0) {
+      // Run the search immediately so the Sidebar click feels
+      // responsive (no debounce delay).
+      scheduleSearch();
+    }
+  }
+
   async function handleLogout() {
     try {
       await session.logout();
       setView("home");
-      profile = null;
       searchResults = [];
       threadRoot = null;
       threadParent = null;
@@ -392,13 +438,6 @@
   // Derive a display handle. The session already gives us the user's
   // real handle (e.g. "alice.bsky.social"). When the AppView decorates
   // posts that have empty handles it falls back to a synthetic
-  // "@did:plc:abcd…" form, so the fallback here matches that.
-  function displayHandle(h: string | null | undefined): string {
-    if (!h) return "@unknown";
-    if (h.startsWith("@")) return h;
-    return `@${h}`;
-  }
-
   // Mirror the URLs the Rust shell reads from MAARCADETWEET_PDS_URL /
   // MAARCADETWEET_APPVIEW_URL (see `crates/tauri-app/src-tauri/src/lib.rs`).
   // Used in the Settings view to show which backends the client is
@@ -434,6 +473,7 @@
       on_select={(v) => setView(v)}
     />
     <div class="main">
+      <div class="main-inner">
       <Terminal title={view === "home" ? "maarcadetweet — home" : `maarcadetweet — ${view}`}>
         {#if view === "home"}
           <div class="head">
@@ -442,6 +482,20 @@
             <span class="as">@{currentUser.handle}</span>
             <span class="meta">→ {userPosts.length} posts · polling every 5s</span>
           </div>
+          <nav class="tabs" aria-label="Timeline">
+            <button
+              class="tab"
+              type="button"
+              disabled
+              title="for you — algo coming soon"
+            >for you</button>
+            <button
+              class="tab"
+              class:tab--active={homeTab === "following"}
+              type="button"
+              onclick={() => (homeTab = "following")}
+            >following</button>
+          </nav>
           {#if timelineError}
             <div class="toast toast--err">err: {timelineError}</div>
           {/if}
@@ -462,14 +516,14 @@
                   <div class="toast toast--err">err: {threadError}</div>
                 {:else if threadRoot}
                   {#if threadParent && threadParent.uri !== threadRoot.uri}
-                    <div class="thread-parent"><PostCard post={threadParent} /></div>
+                    <div class="thread-parent"><PostCard post={threadParent} on_handle_click={openUserProfile} on_reply={onReply} /></div>
                   {/if}
-                  <PostCard post={threadRoot} />
+                  <PostCard post={threadRoot} on_handle_click={openUserProfile} on_reply={onReply} />
                 {/if}
               </div>
             {/if}
             {#each userPosts as p (p.uri)}
-              <PostCard post={p} on_thread_click={openThread} />
+              <PostCard post={p} on_thread_click={openThread} on_handle_click={openUserProfile} on_reply={onReply} />
             {/each}
             {#if timelineCursor}
               <div class="loadmore">
@@ -486,165 +540,165 @@
             <span class="as">@{currentUser.handle}</span>
             <span class="meta">⌘↵ to post</span>
           </div>
-          <ComposeBox onPosted={handlePosted} />
-        {:else if view === "profile"}
+          <ComposeBox
+            onPosted={handlePosted}
+            replyTo={replyTo}
+            onClearReply={clearReply}
+          />
+        {:else if view === "user"}
           <div class="head">
             <span class="prompt">$</span>
             <span class="title">// profile —</span>
-            <span class="as">@{currentUser.handle}</span>
+            <span class="as">@{selectedHandle}</span>
           </div>
-          {#if profileLoading && !profile}
-            <Skeleton rows={4} />
-          {:else if profileError}
-            <div class="toast toast--err">err: {profileError}</div>
-          {:else if profile}
-            <section class="profile">
-              <header class="profile__head">
-                <div class="profile__handle">{displayHandle(profile.handle)}</div>
-                <div class="profile__did" title={profile.did}>{profile.did}</div>
-              </header>
-
-              <div class="profile__actions">
-                <button
-                  class="btn btn--ghost"
-                  type="button"
-                  title="Copy DID to clipboard"
-                  onclick={() => copyToClipboard(profile!.did)}
-                >copy did</button>
-                <button
-                  class="btn btn--ghost"
-                  type="button"
-                  title="Copy AT URI to clipboard"
-                  onclick={() =>
-                    copyToClipboard(`at://${profile!.did}/app.twi.post`)}
-                >copy at-uri</button>
-                <button
-                  class="btn btn--ghost"
-                  type="button"
-                  title="Open profile in your default browser"
-                  onclick={() =>
-                    openExternalUrl(
-                      `https://bsky.app/profile/${profile!.handle}`,
-                    )}
-                >open in browser</button>
-                <button
-                  class="btn btn--ghost"
-                  type="button"
-                  title="Sign out of this app"
-                  onclick={handleLogout}
-                >sign out</button>
-              </div>
-
-              <dl class="counts">
-                <div>
-                  <dt>followers</dt>
-                  <dd>{profile.followers}</dd>
-                </div>
-                <div>
-                  <dt>following</dt>
-                  <dd>{profile.following}</dd>
-                </div>
-                <div>
-                  <dt>posts</dt>
-                  <dd>{profile.posts.length}</dd>
-                </div>
-              </dl>
-
-              {#if profile.posts.length === 0}
-                <div class="empty">// no posts yet — compose your first one</div>
-              {:else}
-                <h3 class="profile__h3">// recent posts</h3>
-                {#each profile.posts as p (p.uri)}
-<PostCard post={p} on_thread_click={openThread} />
-                {/each}
-              {/if}
-            </section>
+          <ProfileView
+            handle={selectedHandle}
+            on_thread_click={openThread}
+            current_user_did={currentUser?.did ?? null}
+          />
+        {:else if view === "profile"}
+          {#if currentUser}
+            <div class="head">
+              <span class="prompt">$</span>
+              <span class="title">// profile —</span>
+              <span class="as">@{currentUser.handle}</span>
+            </div>
+            <ProfileView
+              handle={currentUser.handle}
+              on_thread_click={openThread}
+              current_user_did={currentUser.did}
+            />
           {/if}
         {:else if view === "settings"}
           <div class="head">
             <span class="prompt">$</span>
             <span class="title">// settings</span>
+            <span class="meta">@{currentUser?.handle ?? "?"}</span>
           </div>
           <section class="settings">
-            <h3 class="settings__h3">// account</h3>
-            <dl class="settings__rows">
-              <div>
-                <dt>handle</dt>
-                <dd>@{currentUser?.handle ?? "?"}</dd>
+            <!-- Account — X-style rows: label left, value right, full-width clickable -->
+            <div class="settings__group">
+              <h3 class="settings__h3">// account</h3>
+              <div class="settings__list">
+                <div class="settings__row">
+                  <span class="settings__label">handle</span>
+                  <span class="settings__value">@{currentUser?.handle ?? "?"}</span>
+                </div>
+                <div class="settings__row">
+                  <span class="settings__label">did</span>
+                  <code class="settings__value settings__value--mono">{currentUser?.did ?? "?"}</code>
+                </div>
+                <div class="settings__row">
+                  <span class="settings__label">posts cached</span>
+                  <span class="settings__value">{userPosts.length}</span>
+                </div>
               </div>
-              <div>
-                <dt>did</dt>
-                <dd class="did-cell">{currentUser?.did ?? "?"}</dd>
+              <div class="settings__actions">
+                <button
+                  class="settings__action"
+                  type="button"
+                  onclick={() =>
+                    currentUser && copyToClipboard(currentUser.did)}
+                >
+                  <span>copy did</span>
+                  <span class="settings__action-hint">atproto</span>
+                </button>
+                <button
+                  class="settings__action"
+                  type="button"
+                  onclick={() =>
+                    openExternalUrl(
+                      `https://bsky.app/profile/${currentUser?.handle ?? ""}`,
+                    )}
+                >
+                  <span>open profile in browser</span>
+                  <span class="settings__action-hint">↗ bsky.app</span>
+                </button>
+                <button
+                  class="settings__action"
+                  type="button"
+                  onclick={() => setView("home")}
+                >
+                  <span>← back to timeline</span>
+                </button>
               </div>
-              <div>
-                <dt>posts in cache</dt>
-                <dd>{userPosts.length}</dd>
-              </div>
-            </dl>
-
-            <h3 class="settings__h3">// actions</h3>
-            <div class="settings__actions">
-              <button
-                class="btn btn--ghost"
-                type="button"
-                onclick={() =>
-                  currentUser && copyToClipboard(currentUser.did)}
-              >copy my did</button>
-              <button
-                class="btn btn--ghost"
-                type="button"
-                onclick={() =>
-                  openExternalUrl(
-                    `https://bsky.app/profile/${currentUser?.handle ?? ""}`,
-                  )}
-              >open profile in browser</button>
-              <button
-                class="btn btn--ghost"
-                type="button"
-                onclick={() => setView("home")}
-              >← back to timeline</button>
             </div>
 
-            <h3 class="settings__h3">// about</h3>
-            <dl class="settings__rows">
-              <div>
-                <dt>app</dt>
-                <dd>maarcadetweet</dd>
+            <!-- Backend / connection info — same row pattern -->
+            <div class="settings__group">
+              <h3 class="settings__h3">// backend</h3>
+              <div class="settings__list">
+                <div class="settings__row">
+                  <span class="settings__label">app</span>
+                  <span class="settings__value">maarcadetweet</span>
+                </div>
+                <div class="settings__row">
+                  <span class="settings__label">version</span>
+                  <span class="settings__value">0.1.0</span>
+                </div>
+                <div class="settings__row">
+                  <span class="settings__label">pds</span>
+                  <code class="settings__value settings__value--mono">{pdsBase()}</code>
+                </div>
+                <div class="settings__row">
+                  <span class="settings__label">appview</span>
+                  <code class="settings__value settings__value--mono">{appviewBase()}</code>
+                </div>
               </div>
-              <div>
-                <dt>version</dt>
-                <dd>0.1.0</dd>
-              </div>
-              <div>
-                <dt>backend</dt>
-                <dd>{pdsBase()}</dd>
-              </div>
-              <div>
-                <dt>appview</dt>
-                <dd>{appviewBase()}</dd>
-              </div>
-            </dl>
+            </div>
 
-            <div class="settings__signout">
-              <button
-                class="btn btn--ghost btn--danger"
-                type="button"
-                onclick={handleLogout}
-              >sign out</button>
+            <!-- Sign-out — separate danger zone at the bottom, like X's "Log out" row -->
+            <div class="settings__group settings__group--danger">
+              <div class="settings__list">
+                <button
+                  class="settings__action settings__action--danger"
+                  type="button"
+                  onclick={handleLogout}
+                >
+                  <span>sign out</span>
+                  <span class="settings__action-hint">→</span>
+                </button>
+              </div>
             </div>
           </section>
         {:else if view === "search"}
           <div class="head">
             <span class="prompt">$</span>
-            <span class="title">// search</span>
+            <span class="title">// search —</span>
+            <input
+              class="search"
+              type="text"
+              bind:value={searchQuery}
+              oninput={onSearchInput}
+              placeholder="grep posts…"
+            />
           </div>
-          <input
-            class="search"
-            type="text"
-            bind:value={searchQuery}
-            oninput={onSearchInput}
-            placeholder="grep posts…"
-          />
+          <nav class="tabs" aria-label="Search sections">
+            <button
+              class="tab"
+              class:tab--active={searchTab === "top"}
+              type="button"
+              onclick={() => (searchTab = "top")}
+            >top</button>
+            <button
+              class="tab"
+              type="button"
+              disabled
+              title="latest — coming soon"
+            >latest</button>
+            <button
+              class="tab"
+              type="button"
+              disabled
+              title="people — coming soon"
+            >people</button>
+            <button
+              class="tab"
+              type="button"
+              disabled
+              title="photos — coming soon"
+            >photos</button>
+          </nav>
           {#if searchError}
             <div class="toast toast--err">err: {searchError}</div>
           {/if}
@@ -657,11 +711,15 @@
           {:else}
             <div class="meta meta--results">{searchResults.length} result{searchResults.length === 1 ? "" : "s"} for "{searchQuery}"</div>
             {#each searchResults as p (p.uri)}
-              <PostCard post={p} on_thread_click={openThread} />
+              <PostCard post={p} on_thread_click={openThread} on_handle_click={openUserProfile} on_reply={onReply} />
             {/each}
           {/if}
         {/if}
       </Terminal>
+      {#if view === "home"}
+        <Sidebar posts={userPosts} onSearch={onSidebarSearch} />
+      {/if}
+      </div>
     </div>
     <StatusBar did={status.did ?? ""} authenticated={status.authenticated} />
   </div>
@@ -751,12 +809,51 @@
     overflow: auto;
     padding: var(--s-3);
   }
-
-  .profile__actions {
+  .main-inner {
     display: flex;
-    gap: var(--s-2);
-    margin: var(--s-3) 0;
+    gap: var(--s-3);
+    align-items: flex-start;
+    min-width: 0;
   }
+  .main-inner > :global(.terminal) {
+    flex: 1 1 auto;
+    min-width: 0;
+  }
+
+  /* Tab strip — mirrors the ProfileView's `.tab` pattern so the
+     home + search tabs read as siblings of the profile tabs. */
+  .tabs {
+    display: flex;
+    border-bottom: 1px solid var(--line);
+    margin: 0 0 var(--s-3);
+  }
+  .tab {
+    flex: 1;
+    background: none;
+    border: 0;
+    padding: var(--s-3);
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    cursor: pointer;
+    border-bottom: 2px solid transparent;
+    transition:
+      color var(--dur) var(--ease),
+      border-color var(--dur) var(--ease);
+  }
+  .tab:hover:not(:disabled) {
+    color: var(--text);
+  }
+  .tab:disabled {
+    cursor: not-allowed;
+    opacity: 0.5;
+  }
+  .tab--active {
+    color: var(--orange);
+    border-bottom-color: var(--orange);
+    font-weight: 700;
+  }
+
   .head {
     font-family: var(--font-mono);
     font-size: var(--fs-50);
@@ -829,51 +926,6 @@
   .btn--ghost:hover:not(:disabled) { color: var(--orange); border-color: var(--orange); }
   .btn:disabled { opacity: 0.4; cursor: not-allowed; }
 
-  .profile {
-    padding: 0 var(--s-3);
-  }
-  .profile__head {
-    display: flex;
-    flex-direction: column;
-    gap: var(--s-1);
-    padding: var(--s-3) 0 var(--s-4);
-    border-bottom: 1px solid var(--line);
-    margin-bottom: var(--s-3);
-  }
-  .profile__handle {
-    font-family: var(--font-mono);
-    font-weight: 700;
-    font-size: var(--fs-200);
-    color: var(--orange);
-  }
-  .profile__did {
-    font-family: var(--font-mono);
-    font-size: var(--fs-50);
-    color: var(--text-dim);
-    word-break: break-all;
-  }
-  .counts {
-    display: flex;
-    gap: var(--s-6);
-    padding: var(--s-2) var(--s-4);
-    margin: 0 0 var(--s-4);
-    font-family: var(--font-mono);
-    font-size: var(--fs-50);
-  }
-  .counts > div {
-    display: flex;
-    flex-direction: column;
-    gap: 2px;
-  }
-  .counts dt { color: var(--text-dim); letter-spacing: 0.04em; }
-  .counts dd {
-    margin: 0;
-    color: var(--text);
-    font-weight: 700;
-    font-size: var(--fs-200);
-    font-variant-numeric: tabular-nums;
-  }
-
   .toasts {
     position: fixed;
     right: var(--s-4);
@@ -903,68 +955,124 @@
     background: rgba(255, 59, 48, 0.08);
   }
 
-  .btn--danger {
-    color: var(--red);
-    border-color: var(--red);
-  }
-  .btn--danger:hover:not(:disabled) {
-    background: rgba(255, 59, 48, 0.08);
-    color: var(--red);
-    border-color: var(--red);
-  }
+  /* (the legacy .btn--danger class used to be applied to the
+     "sign out" button — that's now styled via
+     `.settings__group--danger .settings__action` which is its own
+     selector tree in the settings section below) */
 
-  .profile__h3,
+  /* X-style settings page: sectioned cards with label-left /
+     value-right rows, then a list of clickable action rows, then
+     a danger zone at the bottom. Stays monospace + terminal-
+     commented, but the structure is the same as X's. */
+  .settings {
+    padding: 0 var(--s-3) var(--s-6);
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-4);
+  }
+  .settings__group {
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-2);
+  }
   .settings__h3 {
     font-family: var(--font-mono);
     font-size: var(--fs-50);
-    color: var(--text-dim);
-    letter-spacing: 0.04em;
-    margin: var(--s-4) 0 var(--s-2);
-    font-weight: 400;
+    color: var(--orange);
+    letter-spacing: var(--tracking-label);
+    margin: 0;
+    font-weight: 700;
   }
-
-  .did-cell {
-    word-break: break-all;
-    font-size: var(--fs-50);
-  }
-
-  .settings {
-    padding: 0 var(--s-3);
+  .settings__list {
     display: flex;
     flex-direction: column;
-    gap: var(--s-2);
+    background: var(--bg-elev);
+    border: 1px solid var(--line);
+    border-radius: var(--r-md);
+    overflow: hidden;
   }
-  .settings__rows {
+  /* Each row is a label-left / value-right flex line, separated
+     by a hairline (X uses a single border on each row except the
+     last). */
+  .settings__row {
     display: flex;
-    flex-direction: column;
-    gap: var(--s-1);
-    padding: var(--s-2) var(--s-4);
-    margin: 0 0 var(--s-4);
+    align-items: center;
+    justify-content: space-between;
+    gap: var(--s-3);
+    padding: var(--s-3) var(--s-4);
+    border-bottom: 1px solid var(--line);
     font-family: var(--font-mono);
     font-size: var(--fs-50);
   }
-  .settings__rows > div {
-    display: flex;
-    gap: var(--s-3);
+  .settings__list .settings__row:last-child {
+    border-bottom: 0;
   }
-  .settings__rows dt {
+  .settings__label {
     color: var(--text-dim);
-    letter-spacing: 0.04em;
-    min-width: 9rem;
+    letter-spacing: var(--tracking-label);
+    flex: 0 0 auto;
   }
-  .settings__rows dd {
-    margin: 0;
+  .settings__value {
     color: var(--text);
+    text-align: right;
+    word-break: break-all;
+    min-width: 0;
   }
+  .settings__value--mono {
+    font-size: var(--fs-50);
+  }
+  /* Actions live in their own list — same border-radius but each
+     item is a full-width clickable button. The hint on the right
+     (e.g. "atproto", "↗ bsky.app") is a dim secondary label, the
+     same way X shows the destination on follow / open-in-app
+     rows. */
   .settings__actions {
     display: flex;
-    flex-wrap: wrap;
-    gap: var(--s-2);
-    margin: 0 0 var(--s-4);
+    flex-direction: column;
+    background: var(--bg-elev);
+    border: 1px solid var(--line);
+    border-radius: var(--r-md);
+    overflow: hidden;
   }
-  .settings__signout {
-    margin-top: var(--s-4);
-    padding-top: var(--s-4);
-    border-top: 1px dashed var(--line);
+  .settings__action {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    gap: var(--s-3);
+    padding: var(--s-3) var(--s-4);
+    background: transparent;
+    border: 0;
+    border-bottom: 1px solid var(--line);
+    color: var(--text);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    text-align: left;
+    cursor: pointer;
+    transition: background-color var(--dur) var(--ease),
+      color var(--dur) var(--ease);
+  }
+  .settings__actions .settings__action:last-child {
+    border-bottom: 0;
+  }
+  .settings__action:hover {
+    background: var(--orange-8);
+    color: var(--orange);
+  }
+  .settings__action-hint {
+    color: var(--text-dim);
+    font-size: var(--fs-50);
+  }
+  .settings__action:hover .settings__action-hint {
+    color: var(--orange);
+  }
+  .settings__group--danger .settings__action {
+    color: var(--red);
+  }
+  .settings__group--danger .settings__action:hover {
+    background: rgba(255, 59, 48, 0.08);
+    color: var(--red);
+  }
+  .settings__group--danger {
+    margin-top: var(--s-3);
   }
 </style>

crates/tauri-app/src/lib/api/client.ts

@@ -24,6 +24,33 @@ async function tauriCall<T>(cmd: string, fallback: T, args?: Record<string, unkn
   return invoke<T>(cmd, args);
 }
 
+/// Base URLs the Tauri shell was started with. Exposed via the
+/// `get_api_urls` command so the Svelte components can build
+/// absolute fetch URLs — a relative `/api/...` resolves against
+/// the Vite dev origin (port 1430), not the AppView (port 2584),
+/// and `response.json()` then throws `SyntaxError` on the 404
+/// HTML page. Cached after the first successful call.
+let _apiUrlsCache: { pdsUrl: string; appviewUrl: string } | null = null;
+
+export type ApiUrls = { pdsUrl: string; appviewUrl: string };
+
+/// Fetch the AppView + PDS base URLs from the Rust shell. Returns
+/// the cached value on subsequent calls.
+export async function getApiUrls(): Promise<ApiUrls> {
+  if (_apiUrlsCache) return _apiUrlsCache;
+  const urls = await safeInvoke<ApiUrls>("get_api_urls");
+  _apiUrlsCache = urls;
+  return urls;
+}
+
+/// Convenience: just the AppView base URL (the only one the UI
+/// currently needs for direct fetch calls). Same caching as
+/// `getApiUrls`.
+export async function getAppviewUrl(): Promise<string> {
+  const { appviewUrl } = await getApiUrls();
+  return appviewUrl;
+}
+
 /**
  * Strict variant of `tauriCall` for actions that MUST hit the
  * Tauri runtime (login, register, logout, post, like, etc.). In
@@ -191,6 +218,11 @@ export type Post = {
   embed?: Embed | null;
   langs: string[];
   created_at: string;
+  like_count?: number;
+  repost_count?: number;
+  /// Resolved author-avatar CID from the AppView's `profiles`
+  /// cache. NULL when the user has no profile record yet.
+  avatar_cid?: string | null;
 };
 
 export type TimelineResponse = {
@@ -204,6 +236,11 @@ export type ProfileResponse = {
   posts: Post[];
   followers: number;
   following: number;
+  display_name?: string | null;
+  description?: string | null;
+  avatar_cid?: string | null;
+  banner_cid?: string | null;
+  post_count: number;
 };
 
 export type SearchResponse = {
@@ -228,9 +265,20 @@ export type ThreadResponse = {
   repost_count?: number;
 };
 
+/// Reply block for `app.bsky.feed.post#reply`. Both `root` and
+/// `parent` are `com.atproto.repo.strongRef`s (uri + cid). For a
+/// top-level reply to a single post, `root` and `parent` point at
+/// the same strongRef. The Rust `post_create` command wires this
+/// onto the record's `reply` field.
+export type ReplyRef = {
+  root: { uri: string; cid: string };
+  parent: { uri: string; cid: string };
+};
+
 export async function createPost(
   text: string,
   embed?: unknown | null,
+  reply?: ReplyRef | null,
 ): Promise<Post> {
   // The Rust post_create command returns a different shape (uri+cid
   // only), but we keep the call simple: it gives us the cid we need
@@ -238,9 +286,12 @@ export async function createPost(
   // `embed` is forwarded verbatim; the caller is responsible for
   // shaping it as an `app.bsky.embed.images` / `.external` / etc.
   // record. Pass `null` or `undefined` to omit.
+  // `reply` is the reply block (root + parent strongRefs); `null` or
+  // `undefined` means "top-level post" (no reply block on the record).
   return await safeInvoke<any>("post_create", {
     text,
     embed: embed ?? null,
+    reply: reply ?? null,
   });
 }
 
@@ -370,10 +421,28 @@ export async function unrepostPost(
   return await safeInvoke<DeleteRecordResult>("unrepost_post", { repostUri });
 }
 
-/// Fire-and-forget user-visible error toast. Implemented as a
-/// `window` `CustomEvent` so any component can show errors without
-/// pulling in a global store. `App.svelte` listens for the event
-/// and renders the toast UI.
+/// `followUser(targetDid)` — create an `app.bsky.graph.follow` record
+/// on the user's PDS. Returns `{ uri, cid }` — the client caches
+/// `uri` in localStorage so `unfollowUser(uri)` can delete the
+/// record without needing a "list my follows" round-trip.
+export async function followUser(
+  targetDid: string,
+): Promise<RepoWriteResult> {
+  return await safeInvoke<RepoWriteResult>("follow_user", { targetDid });
+}
+
+export async function unfollowUser(
+  followUri: string,
+): Promise<DeleteRecordResult> {
+  return await safeInvoke<DeleteRecordResult>("unfollow_user", {
+    followUri,
+  });
+}
+
+/// Fire-and-forget user-visible toast. Implemented as a `window`
+/// `CustomEvent` so any component can show toasts without pulling
+/// in a global store. `App.svelte` listens for the event and
+/// renders the toast UI.
 export function showError(text: string): void {
   if (typeof window === "undefined") return;
   window.dispatchEvent(
@@ -381,6 +450,13 @@ export function showError(text: string): void {
   );
 }
 
+export function showInfo(text: string): void {
+  if (typeof window === "undefined") return;
+  window.dispatchEvent(
+    new CustomEvent("maarcadetweet:toast", { detail: { kind: "info", text } }),
+  );
+}
+
 /// Show a native OS notification. Thin wrapper around the
 /// `show_notification` Tauri command. The Rust side also emits an
 /// `app://notification` event with the same payload, so the click
@@ -429,6 +505,33 @@ export async function listenTrayEvents(
 /// browser preview where no Tauri runtime is present, fall back
 /// to `window.open` and treat a popup-blocker denial as
 /// "fine, user can copy the URL themselves".
+export type ProfileRecord = {
+  displayName?: string;
+  description?: string;
+  avatar?: { ref: { $link: string }; mimeType?: string; size?: number };
+  banner?: { ref: { $link: string }; mimeType?: string; size?: number };
+};
+
+/// Read the authenticated user's `app.bsky.actor.profile` record.
+/// Returns `null` if no profile record exists yet (a brand-new
+/// account, or a user whose PDS hasn't pushed one).
+export async function getMyProfile(): Promise<ProfileRecord | null> {
+  return await safeInvoke<ProfileRecord | null>("profile_get_record");
+}
+
+/// Read-modify-write the authenticated user's profile. The Rust
+/// `profile_set` command fetches the existing record, overlays
+/// the supplied fields, and writes a new commit. `undefined` fields
+/// are preserved.
+export async function setMyProfile(fields: {
+  displayName?: string;
+  description?: string;
+  avatarBlobCid?: string;
+  bannerBlobCid?: string;
+}): Promise<ProfileRecord | null> {
+  return await safeInvoke<ProfileRecord | null>("profile_set", fields);
+}
+
 export async function openExternalUrl(url: string): Promise<void> {
   try {
     if (isTauri()) {

crates/tauri-app/src/lib/components/Avatar.svelte

@@ -0,0 +1,92 @@
+<script lang="ts">
+  import { fetchBlob } from "../api/client";
+  import { onDestroy } from "svelte";
+
+  type Props = {
+    did: string;
+    /** Blob-ref `$link` from a posts/post record or a profile
+     *  record. The Avatar component resolves the (did, cid) pair via
+     *  the existing PDS `getBlob` route through `fetchBlob`. NULL
+     *  falls back to the deterministic initial-letter SVG. */
+    cid?: string | null;
+    /** Human-readable name used for the initial-letter fallback and
+     *  the alt text. */
+    name?: string | null;
+    /** Pixel size. The same component is used at 24 px (PostCard),
+     *  32 px (Header current-user avatar) and 88 px (Profile-View
+     *  header). */
+    size?: number;
+  };
+
+  let { did, cid = null, name = "", size = 32 }: Props = $props();
+  const initial = $derived(
+    ((name || "").trim()[0] || "?").toUpperCase(),
+  );
+  let blobUrl: string | null = $state(null);
+  let lastCid: string | null = null;
+
+  $effect(() => {
+    // Drop the previous blob URL when the CID changes — keeps the
+    // in-memory cache (managed by `fetchBlob`) lean and avoids leaking
+    // object URLs across navigations.
+    if (lastCid !== cid) {
+      if (blobUrl) URL.revokeObjectURL(blobUrl);
+      blobUrl = null;
+      lastCid = cid;
+    }
+    if (!cid) return;
+    let cancelled = false;
+    fetchBlob(did, cid)
+      .then((u) => {
+        if (!cancelled) blobUrl = u;
+        else URL.revokeObjectURL(u);
+      })
+      .catch(() => {
+        /* Fall back to the initial letter on fetch error. */
+      });
+    return () => {
+      cancelled = true;
+    };
+  });
+
+  onDestroy(() => {
+    if (blobUrl) URL.revokeObjectURL(blobUrl);
+  });
+</script>
+
+{#if blobUrl}
+  <img
+    class="avatar"
+    style:width="{size}px"
+    style:height="{size}px"
+    src={blobUrl}
+    alt={name ? `${name}'s avatar` : "avatar"}
+  />
+{:else}
+  <span
+    class="avatar avatar--fallback"
+    style:width="{size}px"
+    style:height="{size}px"
+    style:font-size="{Math.max(10, Math.floor(size * 0.45))}px"
+  >
+    {initial}
+  </span>
+{/if}
+
+<style>
+  .avatar {
+    display: inline-block;
+    border-radius: 50%;
+    object-fit: cover;
+    background: var(--bg-elev, #1a1a1a);
+    flex-shrink: 0;
+  }
+  .avatar--fallback {
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    font-family: var(--font-mono, monospace);
+    color: var(--text-dim, #888);
+    border: 1px solid var(--line-2, #3a3a3a);
+  }
+</style>

crates/tauri-app/src/lib/components/ComposeBox.svelte

@@ -8,27 +8,37 @@
     releaseBlob,
     session,
     type Post,
+    type Session,
+    type ReplyRef,
   } from "../api/client";
+  import Avatar from "./Avatar.svelte";
+
+  /// Reply target. The parent/root strongRefs are required so the
+  /// resulting post can carry the `reply` block on its record.
+  type ReplyTarget = {
+    handle: string;
+    root: { uri: string; cid: string };
+    parent: { uri: string; cid: string };
+  };
+
+  type Props = {
+    onPosted?: () => void;
+    replyTo?: ReplyTarget | null;
+    onClearReply?: () => void;
+  };
 
   const MAX = 160;
-  let { onPosted }: { onPosted?: () => void } = $props();
-  let text: string = $state("");
-  let isPosting: boolean = $state(false);
-  let isAttaching: boolean = $state(false);
+  let { onPosted, replyTo = null, onClearReply }: Props = $props();
+  let text = $state("");
+  let isPosting = $state(false);
+  let isAttaching = $state(false);
   let status: { kind: "ok" | "err" | "info"; msg: string } | null = $state(null);
+  let currentUser: Session | null = $state(null);
 
-  // Currently logged-in user. We need the DID for `fetchBlob` (the
-  // PDS endpoint keys blobs by `(did, cid)`), so the compose box
-  // subscribes to the session store rather than taking a prop.
-  let did: string = $state("");
   $effect(() => {
-    const u = $session;
-    did = u?.did ?? "";
+    currentUser = $session;
   });
 
-  // The currently-attached image. `null` = no attachment. We hold
-  // the blob reference + a local object URL for the preview so the
-  // user sees the image before they post.
   let attachment: {
     cid: string;
     mimeType: string;
@@ -36,267 +46,417 @@
     previewUrl: string;
   } | null = $state(null);
 
-  let remaining = $derived(MAX - text.length);
-  let counterClass = $derived(
-    remaining < 0 ? "counter counter--err" :
-    remaining < 40 ? "counter counter--warn" : "counter"
+  // Count graphemes, not UTF-16 code units. atproto enforces
+  // `maxLength: 160` as graphemes, so a single 🚀 (surrogate pair)
+  // must count as 1, not 2. `Intl.Segmenter` is built into the
+  // runtime — no dependency needed.
+  const seg = new Intl.Segmenter("en", { granularity: "grapheme" });
+  const count = $derived(text.trim().length === 0 ? 0 : [...seg.segment(text)].length);
+  const isTooLong = $derived(count > MAX);
+  const isAtMax = $derived(count === MAX);
+  // atproto's `maxLength: 160` is inclusive of the 160th grapheme
+  // — the spec rejects any record whose text length exceeds 160.
+  // So we treat `count === MAX` as "exactly at the cap, still
+  // shippable" and only flag as an error on strict overflow.
+  const counterClass = $derived(
+    isTooLong
+      ? "counter counter--err"
+      : isAtMax
+        ? "counter counter--warn"
+        : count >= MAX - 30
+          ? "counter counter--warn"
+          : "counter",
   );
+  const canPost = $derived(!!text.trim() && !isTooLong && !isPosting);
 
-  function handleKeydown(e: KeyboardEvent) {
-    if ((e.metaKey || e.ctrlKey) && e.key === "Enter") {
-      e.preventDefault();
-      post();
+  function handleKeydown(event: KeyboardEvent) {
+    if ((event.metaKey || event.ctrlKey) && event.key === "Enter") {
+      event.preventDefault();
+      void post();
     }
   }
 
-  function fmtBytes(n: number): string {
-    if (n < 1024) return `${n} B`;
-    if (n < 1024 * 1024) return `${(n / 1024).toFixed(1)} KiB`;
-    return `${(n / (1024 * 1024)).toFixed(2)} MiB`;
+  function fmtBytes(bytes: number) {
+    if (bytes < 1024) return `${bytes} B`;
+    if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KiB`;
+    return `${(bytes / (1024 * 1024)).toFixed(2)} MiB`;
   }
 
   async function attach() {
     if (isAttaching || attachment) return;
-    if (!did) {
-      status = { kind: "err", msg: "> log in first" };
+    if (!currentUser?.did) {
+      status = { kind: "err", msg: "log in to add an image" };
       return;
     }
     isAttaching = true;
-    status = { kind: "info", msg: "> picking…" };
+    status = null;
     try {
       const blob = await pickAndUploadImage();
-      if (!blob) {
-        // User cancelled — restore the previous status rather than
-        // leaving the "picking…" message on screen.
-        status = null;
-        return;
-      }
-      // Fetch the bytes back from the PDS so we can render the
-      // preview. `fetchBlob` caches by CID, so re-rendering the
-      // preview after a re-attach is cheap.
-      const previewUrl = await fetchBlob(did, blob.cid);
+      if (!blob) return;
+      const previewUrl = await fetchBlob(currentUser.did, blob.cid);
       attachment = { ...blob, previewUrl };
-      status = { kind: "info", msg: `> attached (${fmtBytes(blob.size)})` };
-    } catch (e) {
-      status = { kind: "err", msg: `> ${String(e)}` };
+    } catch (error) {
+      status = { kind: "err", msg: String(error) };
     } finally {
       isAttaching = false;
     }
   }
 
   function removeAttachment() {
-    if (attachment) {
-      // Revoke the object URL. `fetchBlob` may have evicted the
-      // cache entry for a different reason, so tolerate a no-op.
-      // The user can re-attach — the next fetch will allocate a
-      // fresh URL.
-      releaseBlob(did, attachment.cid);
-      attachment = null;
-    }
+    if (!attachment || !currentUser?.did) return;
+    releaseBlob(currentUser.did, attachment.cid);
+    attachment = null;
   }
 
   async function post() {
-    if (!text.trim() || remaining < 0 || isPosting) return;
+    if (!canPost) return;
     isPosting = true;
-    status = { kind: "info", msg: "> posting…" };
+    status = { kind: "info", msg: "posting…" };
     try {
       const embed = attachment ? makeImagesEmbed(attachment) : null;
-      const r: Post = await createPost(text, embed);
-      status = { kind: "ok", msg: `> ok (cid: ${(r as any).cid?.slice?.(0, 8) ?? "?"}…)` };
+      const reply: ReplyRef | null = replyTo
+        ? { root: replyTo.root, parent: replyTo.parent }
+        : null;
+      const response: Post = await createPost(text.trim(), embed, reply);
+      status = {
+        kind: "ok",
+        msg: `posted · cid ${(response as any).cid?.slice?.(0, 8) ?? "?"}…`,
+      };
       text = "";
       removeAttachment();
       onPosted?.();
-    } catch (e) {
-      status = { kind: "err", msg: `> ${String(e)}` };
-      showError(`post failed: ${e}`);
+    } catch (error) {
+      status = { kind: "err", msg: String(error) };
+      showError(`post failed: ${error}`);
     } finally {
       isPosting = false;
     }
   }
 </script>
 
-<div class="compose">
-  <div class="compose__head">
-    <span class="title">// compose</span>
-    <span class="handle">@you</span>
-    <span class={counterClass}>{remaining}</span>
+<section class="compose" aria-label={replyTo ? `Reply to @${replyTo.handle}` : "Compose a post"}>
+  <div class="compose__avatar">
+    <Avatar
+      did={currentUser?.did ?? ""}
+      name={currentUser?.handle ?? "you"}
+      size={40}
+    />
   </div>
-  <div class="compose__body">
-    <span class="prompt">$</span>
+
+  <div class="compose__content">
+    {#if replyTo}
+      <div class="replying">
+        <span>Replying to <b>@{replyTo.handle}</b></span>
+        <button type="button" onclick={onClearReply} title="cancel reply" aria-label="Cancel reply">×</button>
+      </div>
+    {/if}
+
     <textarea
       bind:value={text}
       onkeydown={handleKeydown}
-      placeholder="// what's happening in 160 chars?"
+      placeholder={replyTo ? `Reply to @${replyTo.handle}…` : "What's happening?"}
       rows="3"
-      maxlength="500"
+      maxlength={MAX}
+      aria-label="Post text"
     ></textarea>
-  </div>
-  {#if attachment}
-    <div class="compose__attach">
-      <img
-        class="compose__preview"
-        src={attachment.previewUrl}
-        alt="attachment preview"
-      />
-      <div class="compose__attach-meta">
-        <span class="compose__attach-cid" title={attachment.cid}>cid: {attachment.cid.slice(0, 10)}…</span>
-        <span class="compose__attach-mime">{attachment.mimeType}</span>
-        <span class="compose__attach-size">{fmtBytes(attachment.size)}</span>
+
+    {#if attachment}
+      <div class="attachment">
+        <img src={attachment.previewUrl} alt="Attachment preview" />
+        <div class="attachment__meta">
+          <span>{attachment.mimeType}</span>
+          <span>{fmtBytes(attachment.size)}</span>
+        </div>
+        <button
+          type="button"
+          class="attachment__remove"
+          onclick={removeAttachment}
+          disabled={isPosting}
+          title="remove image"
+          aria-label="Remove image"
+        >×</button>
       </div>
+    {/if}
+
+    <div class="compose__footer">
       <button
         type="button"
-        class="compose__attach-remove"
-        onclick={removeAttachment}
-        disabled={isPosting}
-        title="remove attachment"
-      >×</button>
-    </div>
-  {/if}
-  <div class="compose__foot">
-    <span class="hint">⌘↵ to post</span>
-    <div class="actions">
-      <button
-        type="button"
-        class="btn btn--ghost"
+        class="media-button"
         onclick={attach}
         disabled={isAttaching || !!attachment || isPosting}
-        title={attachment ? "image already attached" : "attach image"}
+        title={attachment ? "one image already attached" : "add image"}
       >
-        {isAttaching ? "picking…" : "📎"}
-      </button>
-      <button class="btn btn--ghost" onclick={() => (text = "")} disabled={!text || isPosting}>draft</button>
-      <button class="btn btn--primary" onclick={post} disabled={!text.trim() || remaining < 0 || isPosting}>
-        {isPosting ? "posting…" : "post"}
+        <svg viewBox="0 0 24 24" aria-hidden="true">
+          <rect x="3" y="4" width="18" height="16" rx="2" />
+          <circle cx="8.5" cy="9" r="1.5" />
+          <path d="m4 17 5-5 4 4 3-3 4 4" />
+        </svg>
+        <span>{isAttaching ? "adding…" : "image"}</span>
       </button>
+
+      <div class="compose__submit">
+        <span class={counterClass}>{count}/{MAX}</span>
+        <span class="divider" aria-hidden="true"></span>
+        <button
+          class="post-button"
+          type="button"
+          onclick={post}
+          disabled={!canPost}
+        >
+          {isPosting ? "Posting…" : replyTo ? "Reply" : "Post"}
+        </button>
+      </div>
     </div>
+
+    {#if status}
+      <div class="status status--{status.kind}" role="status">{status.msg}</div>
+    {/if}
   </div>
-  {#if status}
-    <div class="status status--{status.kind}">{status.msg}</div>
-  {/if}
-</div>
+</section>
 
 <style>
   .compose {
-    background: var(--bg-elev);
-    border: 1px solid var(--line-2);
-    border-radius: var(--r-md);
-    margin: var(--s-4) var(--s-5);
-  }
-  .compose__head {
-    display: flex;
-    align-items: center;
+    display: grid;
+    grid-template-columns: 40px minmax(0, 1fr);
     gap: var(--s-3);
-    padding: var(--s-2) var(--s-4);
-    background: var(--bg-deep);
+    padding: var(--s-4);
     border-bottom: 1px solid var(--line);
-    font-family: var(--font-mono);
-    font-size: var(--fs-50);
-  }
-  .title { color: var(--orange); }
-  .handle { color: var(--text-dim); flex: 1; }
-  .counter { color: var(--text-dim); font-variant-numeric: tabular-nums; }
-  .counter--warn { color: var(--orange); }
-  .counter--err { color: var(--red); letter-spacing: 0.05em; }
-  .compose__body {
-    display: flex;
-    align-items: flex-start;
-    gap: var(--s-2);
-    padding: var(--s-3) var(--s-4);
-  }
-  .prompt {
-    color: var(--orange);
-    font-family: var(--font-mono);
-    font-size: var(--fs-100);
-    line-height: 1.7;
-  }
-  textarea {
-    flex: 1;
-    background: transparent;
-    border: 0;
-    color: var(--text);
-    font-family: var(--font-sans);
-    font-size: var(--fs-100);
-    line-height: 1.6;
-    resize: vertical;
-    outline: none;
-    padding: 0;
-  }
-  textarea::placeholder { color: var(--text-dim); }
-  .compose__attach {
-    display: flex;
-    align-items: center;
-    gap: var(--s-3);
-    padding: var(--s-3) var(--s-4);
     background: var(--bg-deep);
-    border-top: 1px dashed var(--line);
   }
-  .compose__preview {
-    width: 64px;
-    height: 64px;
-    object-fit: cover;
-    border-radius: var(--r-sm);
-    border: 1px solid var(--line-2);
-    background: var(--bg);
+
+  .compose__avatar {
+    padding-top: 2px;
   }
-  .compose__attach-meta {
-    display: flex;
-    flex-direction: column;
-    gap: 2px;
-    flex: 1;
-    font-family: var(--font-mono);
-    font-size: var(--fs-50);
-    color: var(--text-dim);
+
+  .compose__content {
+    min-width: 0;
   }
-  .compose__attach-cid { color: var(--cid-fg); }
-  .compose__attach-mime,
-  .compose__attach-size { font-variant-numeric: tabular-nums; }
-  .compose__attach-remove {
-    background: transparent;
-    border: 1px solid var(--line-2);
-    color: var(--text-dim);
-    font-family: var(--font-mono);
-    font-size: var(--fs-100);
-    width: 28px;
-    height: 28px;
-    border-radius: var(--r-sm);
-    cursor: pointer;
-    line-height: 1;
-  }
-  .compose__attach-remove:hover:not(:disabled) {
-    color: var(--red);
-    border-color: var(--red);
-  }
-  .compose__attach-remove:disabled { opacity: 0.4; cursor: not-allowed; }
-  .compose__foot {
+
+  .replying {
     display: flex;
     align-items: center;
     justify-content: space-between;
-    padding: var(--s-2) var(--s-4);
-    border-top: 1px solid var(--line);
-  }
-  .hint { font-family: var(--font-mono); font-size: var(--fs-50); color: var(--text-dim); }
-  .actions { display: flex; gap: var(--s-2); }
-  .btn {
+    margin-bottom: var(--s-2);
+    color: var(--text-dim);
     font-family: var(--font-mono);
     font-size: var(--fs-50);
-    padding: 0.4rem 0.8rem;
-    border-radius: var(--r-sm);
-    border: 1px solid transparent;
+  }
+
+  .replying b {
+    color: var(--orange);
+    font-weight: 400;
+  }
+
+  .replying button {
+    display: grid;
+    width: 24px;
+    height: 24px;
+    place-items: center;
+    border: 0;
+    border-radius: var(--r-pill);
+    background: transparent;
+    color: var(--text-dim);
+    font: inherit;
     cursor: pointer;
-    transition: background var(--dur) var(--ease), color var(--dur) var(--ease);
   }
-  .btn--ghost { color: var(--text-dim); border-color: var(--line-2); background: transparent; }
-  .btn--ghost:hover:not(:disabled) { color: var(--orange); border-color: var(--orange); }
-  .btn--primary { background: var(--orange); color: #1a0d00; font-weight: 700; }
-  .btn--primary:hover:not(:disabled) { background: var(--orange-bright); }
-  .btn:disabled { opacity: 0.4; cursor: not-allowed; }
-  .status {
+
+  .replying button:hover {
+    background: var(--orange-8);
+    color: var(--orange);
+  }
+
+  textarea {
+    display: block;
+    width: 100%;
+    min-height: 88px;
+    padding: var(--s-1) 0 var(--s-3);
+    resize: vertical;
+    border: 0;
+    outline: 0;
+    background: transparent;
+    color: var(--text);
+    font-family: var(--font-mono);
+    font-size: var(--fs-200);
+    line-height: 1.45;
+  }
+
+  textarea::placeholder {
+    color: var(--text-dim);
+  }
+
+  .attachment {
+    position: relative;
+    margin-bottom: var(--s-3);
+    overflow: hidden;
+    border: 1px solid var(--line-2);
+    border-radius: var(--r-lg);
+    background: var(--bg);
+  }
+
+  .attachment img {
+    width: 100%;
+    max-height: 320px;
+    object-fit: cover;
+  }
+
+  .attachment__meta {
+    display: flex;
+    justify-content: space-between;
+    padding: var(--s-2) var(--s-3);
+    color: var(--text-dim);
     font-family: var(--font-mono);
     font-size: var(--fs-50);
-    padding: var(--s-2) var(--s-4);
+  }
+
+  .attachment__remove {
+    position: absolute;
+    top: var(--s-2);
+    right: var(--s-2);
+    display: grid;
+    width: 30px;
+    height: 30px;
+    place-items: center;
+    border: 1px solid var(--line-2);
+    border-radius: var(--r-pill);
+    background: var(--bg-elev);
+    color: var(--text);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    cursor: pointer;
+  }
+
+  .attachment__remove:hover:not(:disabled) {
+    border-color: var(--orange);
+    color: var(--orange);
+  }
+
+  .compose__footer,
+  .compose__submit {
+    display: flex;
+    align-items: center;
+  }
+
+  .compose__footer {
+    min-height: 40px;
+    justify-content: space-between;
+    gap: var(--s-3);
+    padding-top: var(--s-2);
     border-top: 1px solid var(--line);
   }
-  .status--ok { color: var(--green); }
-  .status--err { color: var(--red); }
-  .status--info { color: var(--orange); }
+
+  .compose__submit {
+    gap: var(--s-3);
+  }
+
+  .media-button {
+    display: inline-flex;
+    align-items: center;
+    gap: var(--s-1);
+    padding: var(--s-2);
+    border: 0;
+    border-radius: var(--r-pill);
+    background: transparent;
+    color: var(--orange);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    cursor: pointer;
+  }
+
+  .media-button:hover:not(:disabled) {
+    background: var(--orange-8);
+  }
+
+  .media-button svg {
+    width: 19px;
+    height: 19px;
+    fill: none;
+    stroke: currentColor;
+    stroke-width: 1.7;
+    stroke-linecap: round;
+    stroke-linejoin: round;
+  }
+
+  .media-button:disabled,
+  .post-button:disabled,
+  .attachment__remove:disabled {
+    opacity: 0.4;
+    cursor: not-allowed;
+  }
+
+  .counter {
+    min-width: 5.5rem;
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    font-variant-numeric: tabular-nums;
+    text-align: right;
+  }
+
+  .counter--warn {
+    color: var(--orange);
+  }
+
+  .counter--err {
+    color: var(--red);
+  }
+
+  .divider {
+    width: 1px;
+    height: 24px;
+    background: var(--line-2);
+  }
+
+  .post-button {
+    min-width: 76px;
+    padding: 0.55rem 1rem;
+    border: 0;
+    border-radius: var(--r-pill);
+    background: var(--orange);
+    color: var(--bg-deep);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    font-weight: 700;
+    cursor: pointer;
+    transition: background var(--dur) var(--ease);
+  }
+
+  .post-button:hover:not(:disabled) {
+    background: var(--orange-bright);
+  }
+
+  .status {
+    margin-top: var(--s-2);
+    padding-top: var(--s-2);
+    border-top: 1px dashed var(--line);
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+  }
+
+  .status--ok {
+    color: var(--green);
+  }
+
+  .status--err {
+    color: var(--red);
+  }
+
+  .status--info {
+    color: var(--orange);
+  }
+
+  @media (max-width: 560px) {
+    .compose {
+      padding-inline: var(--s-3);
+    }
+
+    textarea {
+      font-size: var(--fs-100);
+    }
+
+    .media-button span,
+    .divider {
+      display: none;
+    }
+  }
 </style>

crates/tauri-app/src/lib/components/LoginScreen.svelte

@@ -4,7 +4,10 @@
 
   let { onLogin }: { onLogin: (s: Session) => void } = $props();
 
-  let mode: "login" | "register" = $state("register");
+  // Default to "login" — most users opening the app already have an
+  // account, and the empty-autocomplete form now matches the
+  // action-label pair they expect. "register" is one click away.
+  let mode: "login" | "register" = $state("login");
   let handle: string = $state("");
   let password: string = $state("");
   let busy = $state(false);
@@ -42,47 +45,46 @@
     <div class="t">maarcadetweet — {mode}</div>
   </div>
   <div class="terminal-body">
-    <div class="line">
-      <span class="prompt">$</span> maarcadetweet {mode}
-    </div>
-    <div class="line muted">// the timeline that fits in 160 chars.</div>
-    <div class="line">&nbsp;</div>
+    <h1 class="brand">maarcadetweet</h1>
+    <p class="tagline">// the timeline that fits in 160 chars.</p>
     {#if serverInfo}
-      <div class="line muted">// pds: {serverInfo.did ?? "?"}</div>
-      <div class="line muted">// domains: {(serverInfo.available_user_domains ?? []).join(", ")}</div>
+      <div class="meta">
+        <span>// pds: {serverInfo.did ?? "?"}</span>
+        <span>// domains: {(serverInfo.available_user_domains ?? []).join(", ")}</span>
+      </div>
     {/if}
-    <div class="line">&nbsp;</div>
-    <div class="form">
-      <label>
-        <span class="key">handle:</span>
+    <form class="form" onsubmit={(e) => { e.preventDefault(); submit(); }}>
+      <label class="field">
+        <span class="key">handle</span>
         <input
           type="text"
           bind:value={handle}
           placeholder="alice.maarcadetweet.local"
           disabled={busy}
+          autocomplete="username"
         />
       </label>
-      <label>
-        <span class="key">password:</span>
+      <label class="field">
+        <span class="key">password</span>
         <input
           type="password"
           bind:value={password}
           placeholder="≥ 8 chars"
           disabled={busy}
           onkeydown={(e) => e.key === "Enter" && submit()}
+          autocomplete={mode === "register" ? "new-password" : "current-password"}
         />
       </label>
-    </div>
+    </form>
     {#if error}
-      <div class="line err">error: {error}</div>
+      <div class="err">err: {error}</div>
     {/if}
-    <div class="line">&nbsp;</div>
-    <div class="line">
+    <div class="actions">
       <button class="btn btn--primary" onclick={submit} disabled={busy || !handle || !password}>
-        {busy ? "..." : mode === "register" ? "create account" : "login"}
+        {busy ? "..." : mode === "register" ? "create account" : "log in"}
       </button>
       <button class="btn btn--ghost" onclick={() => (mode = mode === "register" ? "login" : "register")} disabled={busy}>
-        {mode === "register" ? "have an account? login" : "no account? register"}
+        {mode === "register" ? "have an account? log in" : "no account? register"}
       </button>
     </div>
   </div>
@@ -94,7 +96,8 @@
     border: 1px solid var(--line-2);
     border-radius: var(--r-lg);
     overflow: hidden;
-    width: min(560px, 92vw);
+    width: min(480px, 92vw);
+    box-shadow: 0 24px 60px -28px rgba(0, 0, 0, 0.8);
   }
   .terminal-head {
     display: flex;
@@ -121,49 +124,109 @@
   }
   .terminal-body {
     font-family: var(--font-mono);
-    font-size: 0.95rem;
-    line-height: 1.85;
-    padding: var(--s-5);
+    padding: var(--s-6) var(--s-5);
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-3);
+  }
+  .brand {
+    margin: 0;
+    color: var(--orange);
+    font-family: var(--font-mono);
+    font-size: var(--fs-400);
+    font-weight: 700;
+    letter-spacing: var(--tracking-tight);
+    line-height: var(--lh-tight);
+    text-align: center;
+  }
+  .tagline {
+    margin: 0;
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    text-align: center;
+  }
+  .meta {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    text-align: center;
   }
-  .line { white-space: pre-wrap; }
-  .muted { color: var(--text-dim); }
-  .prompt { color: var(--orange); }
-  .err { color: var(--red); }
   .form {
     display: flex;
     flex-direction: column;
     gap: var(--s-3);
-    margin: var(--s-4) 0;
+    margin-top: var(--s-3);
   }
-  .form label {
+  .field {
     display: flex;
-    align-items: center;
-    gap: var(--s-3);
+    flex-direction: column;
+    gap: var(--s-1);
+  }
+  .key {
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    letter-spacing: var(--tracking-label);
   }
-  .key { color: var(--orange); width: 90px; flex-shrink: 0; }
   .form input {
-    flex: 1;
     background: var(--bg);
     border: 1px solid var(--line-2);
     color: var(--text);
     font-family: var(--font-mono);
+    font-size: var(--fs-100);
     padding: var(--s-2) var(--s-3);
     border-radius: var(--r-sm);
     outline: none;
+    transition: border-color var(--dur) var(--ease);
   }
   .form input:focus { border-color: var(--orange); }
-  .btn {
+  .form input::placeholder { color: var(--text-dim); }
+  .err {
+    color: var(--red);
     font-family: var(--font-mono);
     font-size: var(--fs-50);
-    padding: 0.5rem 0.8rem;
+    padding: var(--s-2) var(--s-3);
+    border-left: 3px solid var(--red);
+    background: rgba(255, 59, 48, 0.08);
+    border-radius: 0 var(--r-sm) var(--r-sm) 0;
+  }
+  .actions {
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-2);
+    margin-top: var(--s-3);
+  }
+  .btn {
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    padding: var(--s-3) var(--s-4);
     border-radius: var(--r-sm);
     border: 1px solid transparent;
     cursor: pointer;
-    margin-right: var(--s-2);
+    text-align: center;
+    transition:
+      background var(--dur) var(--ease),
+      color var(--dur) var(--ease),
+      border-color var(--dur) var(--ease);
+  }
+  .btn--primary {
+    background: var(--orange);
+    color: #1a0d00;
+    font-weight: 700;
   }
-  .btn--primary { background: var(--orange); color: #1a0d00; font-weight: 700; }
   .btn--primary:hover:not(:disabled) { background: var(--orange-bright); }
-  .btn--ghost { background: transparent; color: var(--text-dim); border-color: var(--line-2); }
-  .btn--ghost:hover:not(:disabled) { color: var(--orange); border-color: var(--orange); }
+  .btn--ghost {
+    background: transparent;
+    color: var(--text-dim);
+    border-color: var(--line-2);
+  }
+  .btn--ghost:hover:not(:disabled) {
+    color: var(--orange);
+    border-color: var(--orange);
+  }
   .btn:disabled { opacity: 0.4; cursor: not-allowed; }
 </style>

crates/tauri-app/src/lib/components/NavRail.svelte

@@ -4,7 +4,7 @@
   // `$bindable`, use a callback prop to bubble state changes up to
   // the parent.
 
-  type View = "home" | "compose" | "profile" | "search" | "settings";
+  type View = "home" | "compose" | "profile" | "user" | "search" | "settings";
 
   let {
     view = "home",

crates/tauri-app/src/lib/components/NavRailHarness.svelte

@@ -5,7 +5,7 @@
 
   import NavRail from "./NavRail.svelte";
 
-  type View = "home" | "compose" | "profile" | "search" | "settings";
+  type View = "home" | "compose" | "profile" | "user" | "search" | "settings";
   let view: View = $state("home");
 </script>
 

crates/tauri-app/src/lib/components/ProfileView.svelte

@@ -0,0 +1,811 @@
+<script lang="ts">
+  import Avatar from "./Avatar.svelte";
+  import PostCard from "./PostCard.svelte";
+  import {
+    setMyProfile,
+    pickAndUploadImage,
+    fetchBlob,
+    releaseBlob,
+    getAppviewUrl,
+    followUser,
+    unfollowUser,
+    showInfo,
+    showError,
+  } from "../api/client";
+  import { localStorageKey } from "../utils/localstorage";
+  import { onDestroy, onMount, untrack } from "svelte";
+
+  type Props = {
+    handle: string;
+    on_thread_click?: (uri: string) => void;
+    /// DID of the authenticated user. When this matches the
+    /// profile's DID, the "edit profile" button is shown; the
+    /// /user-profile/<handle> route is then the user's own
+    /// profile (and the avatar / bio are editable).
+    current_user_did?: string | null;
+  };
+  let { handle, on_thread_click, current_user_did }: Props = $props();
+
+  type State =
+    | { kind: "loading" }
+    | { kind: "error"; message: string }
+    | { kind: "ready"; data: AppViewProfile };
+
+  type AppViewProfile = {
+    did: string;
+    handle: string;
+    posts: AppViewPost[];
+    followers: number;
+    following: number;
+    display_name?: string;
+    description?: string;
+    avatar_cid?: string;
+    banner_cid?: string;
+    post_count: number;
+  };
+
+  type AppViewPost = {
+    uri: string;
+    did: string;
+    handle: string;
+    rkey: string;
+    collection: string;
+    text: string;
+    cid: string;
+    parent_uri?: string | null;
+    root_uri?: string | null;
+    embed?: null;
+    langs: string[];
+    created_at: string;
+    avatar_cid?: string | null;
+  };
+
+  let editing: boolean = $state(false);
+  // Type-annotated so TypeScript keeps the discriminated-union narrowing
+  // when we do `viewModel.kind === "ready"` — otherwise $state infers
+  // the literal `"loading"` from the initial value and the `===`
+  // checks become "no overlap" errors.
+  let viewModel: State = $state({ kind: "loading" } as State);
+  let editName: string = $state("");
+  let editDesc: string = $state("");
+  let editAvatarCid: string | null = $state(null);
+  let saving: boolean = $state(false);
+
+  // Follow state — the AppView has no `viewer_followed` field yet, so
+  // we persist per-viewer follow state in localStorage (keyed by
+  // viewer-did + target-did). `followUri` is the URI of the
+  // `app.bsky.graph.follow` record on the viewer's PDS — the unfollow
+  // command needs it because atproto requires the rkey to delete a
+  // record, and we don't have a "list my follows" endpoint to look
+  // it up server-side.
+  let isFollowing: boolean = $state(false);
+  let followUri: string | null = $state(null);
+  let followBusy: boolean = $state(false);
+
+  // Banner blob URL — fetched via the same path as Avatar (Tauri
+  // getBlob via fetchBlob). Released on unmount or when banner
+  // changes.
+  let bannerUrl: string | null = $state(null);
+  let bannerCidLoaded: string | null = null;
+
+  async function load() {
+    viewModel = { kind: "loading" };
+    try {
+      // Absolute URL because the Tauri webview's origin is the Vite
+      // dev server (port 1430), not the AppView (port 2584) — a
+      // relative `/api/profile/…` would resolve against Vite, hit a
+      // 404 HTML page, and `r.json()` would throw `SyntaxError`.
+      const base = await getAppviewUrl();
+      const r = await fetch(`${base}/api/profile/${encodeURIComponent(handle)}`);
+      if (!r.ok) {
+        viewModel = {
+          kind: "error",
+          message: `profile fetch failed: ${r.status}`,
+        };
+        return;
+      }
+      const data: AppViewProfile = await r.json();
+      viewModel = { kind: "ready", data };
+    } catch (e) {
+      viewModel = { kind: "error", message: String(e) };
+    }
+  }
+
+  $effect(() => {
+    const bannerCid =
+      viewModel.kind === "ready" ? viewModel.data.banner_cid ?? null : null;
+    // Release the previous URL whenever the banner CID changes
+    // (including to/from null). We read the previous-loaded value
+    // through `untrack` because reading + writing `bannerCidLoaded`
+    // inside the same effect would trip Svelte 5's depth guard
+    // (`effect_update_depth_exceeded`).
+    const previous = untrack(() => bannerCidLoaded);
+    if (previous === bannerCid) return;
+    if (bannerUrl) {
+      if (viewModel.kind === "ready" && viewModel.data.did) {
+        releaseBlob(viewModel.data.did, previous ?? "");
+      }
+      URL.revokeObjectURL(bannerUrl);
+      bannerUrl = null;
+    }
+    bannerCidLoaded = bannerCid;
+    if (!bannerCid || viewModel.kind !== "ready") return;
+    const did = viewModel.data.did;
+    let cancelled = false;
+    fetchBlob(did, bannerCid)
+      .then((u) => {
+        if (!cancelled) bannerUrl = u;
+        else URL.revokeObjectURL(u);
+      })
+      .catch(() => {
+        /* fall back to CSS gradient placeholder */
+      });
+    return () => {
+      cancelled = true;
+    };
+  });
+
+  onMount(() => {
+    void load();
+  });
+
+  onDestroy(() => {
+    if (bannerUrl) URL.revokeObjectURL(bannerUrl);
+  });
+
+  const isOwn = $derived(
+    !!current_user_did &&
+      viewModel.kind === "ready" &&
+      viewModel.data.did === current_user_did,
+  );
+  const isEmptyProfile = $derived(
+    viewModel.kind === "ready" &&
+      !viewModel.data.display_name &&
+      !viewModel.data.description &&
+      !viewModel.data.avatar_cid &&
+      !viewModel.data.banner_cid,
+  );
+
+  // Restore follow state from localStorage whenever the profile
+  // (DID) changes. Writes are inside `untrack` so the effect's
+  // reactive dep set is just `[viewModel.kind, viewModel.data.did]`
+  // — without untrack, every write to `isFollowing` / `followUri`
+  // would re-enter the effect and trip Svelte's depth guard.
+  $effect(() => {
+    if (viewModel.kind !== "ready" || !current_user_did) return;
+    const did = viewModel.data.did;
+    const key = localStorageKey(`follow:${current_user_did}:${did}`);
+    untrack(() => {
+      try {
+        const raw = localStorage.getItem(key);
+        if (raw) {
+          const parsed = JSON.parse(raw) as {
+            following: boolean;
+            uri: string | null;
+          };
+          isFollowing = !!parsed.following;
+          followUri = parsed.uri ?? null;
+        } else {
+          isFollowing = false;
+          followUri = null;
+        }
+      } catch {
+        isFollowing = false;
+        followUri = null;
+      }
+    });
+  });
+
+  function persistFollow(following: boolean, uri: string | null) {
+    if (viewModel.kind !== "ready" || !current_user_did) return;
+    const did = viewModel.data.did;
+    const key = localStorageKey(`follow:${current_user_did}:${did}`);
+    try {
+      if (following) {
+        localStorage.setItem(
+          key,
+          JSON.stringify({ following: true, uri }),
+        );
+      } else {
+        localStorage.removeItem(key);
+      }
+    } catch {
+      /* quota / private mode — fall through */
+    }
+  }
+
+  async function onFollowClick() {
+    if (viewModel.kind !== "ready" || !current_user_did) return;
+    if (followBusy) return;
+    const targetDid = viewModel.data.did;
+    if (targetDid === current_user_did) return;
+    followBusy = true;
+    const wasFollowing = isFollowing;
+    const previousUri = followUri;
+    isFollowing = true;
+    try {
+      const resp = await followUser(targetDid);
+      followUri = resp.uri;
+      persistFollow(true, resp.uri);
+      showInfo("followed");
+    } catch (e) {
+      isFollowing = wasFollowing;
+      followUri = previousUri;
+      persistFollow(wasFollowing, previousUri);
+      showError(`follow failed: ${e}`);
+    } finally {
+      followBusy = false;
+    }
+  }
+
+  async function onUnfollowClick() {
+    if (viewModel.kind !== "ready") return;
+    if (followBusy) return;
+    if (!followUri) {
+      // Nothing to unfollow — clear the flag and bail.
+      isFollowing = false;
+      return;
+    }
+    followBusy = true;
+    const wasFollowing = isFollowing;
+    const previousUri = followUri;
+    isFollowing = false;
+    followUri = null;
+    persistFollow(false, null);
+    try {
+      await unfollowUser(previousUri!);
+      showInfo("unfollowed");
+    } catch (e) {
+      isFollowing = wasFollowing;
+      followUri = previousUri;
+      persistFollow(wasFollowing, previousUri);
+      showError(`unfollow failed: ${e}`);
+    } finally {
+      followBusy = false;
+    }
+  }
+
+  function openEdit() {
+    if (viewModel.kind !== "ready") return;
+    editName = viewModel.data.display_name ?? "";
+    editDesc = viewModel.data.description ?? "";
+    editAvatarCid = viewModel.data.avatar_cid ?? null;
+    editing = true;
+  }
+
+  async function saveProfile() {
+    if (viewModel.kind !== "ready") return;
+    saving = true;
+    try {
+      await setMyProfile({
+        displayName: editName || undefined,
+        description: editDesc || undefined,
+        avatarBlobCid: editAvatarCid || undefined,
+      });
+      editing = false;
+      await load();
+    } catch (e) {
+      console.warn("profile save failed", e);
+    } finally {
+      saving = false;
+    }
+  }
+
+  async function pickAndUploadAvatar() {
+    const blob = await pickAndUploadImage();
+    if (!blob) return;
+    editAvatarCid = blob.cid;
+  }
+
+  type Tab = "posts" | "replies" | "likes";
+  let activeTab: Tab = $state("posts");
+</script>
+
+<section class="profile">
+  <!-- ─── banner ────────────────────────────────────────────────── -->
+  <div
+    class="profile__banner"
+    style:background-image={bannerUrl ? `url(${bannerUrl})` : "none"}
+  >
+    {#if !bannerUrl}
+      <!--
+        Placeholder shown when the profile has no banner blob.
+        Subtle orange-tinted terminal grid — keeps the page from
+        looking bare without competing with the avatar.
+      -->
+      <div class="profile__banner-grid" aria-hidden="true"></div>
+    {/if}
+  </div>
+
+  <!-- ─── avatar + actions ──────────────────────────────────────── -->
+  <div class="profile__topbar">
+    <div class="profile__avatar-overlap">
+      {#if viewModel.kind === "ready"}
+        <Avatar
+          did={viewModel.data.did}
+          cid={viewModel.data.avatar_cid ?? null}
+          name={viewModel.data.display_name ?? viewModel.data.handle}
+          size={96}
+        />
+      {:else}
+        <span class="profile__avatar-skeleton"></span>
+      {/if}
+    </div>
+    <div class="profile__actions">
+      {#if viewModel.kind === "ready"}
+        {#if isOwn}
+          {#if editing}
+            <button
+              class="btn btn--ghost"
+              type="button"
+              onclick={() => (editing = false)}
+            >cancel</button>
+          {:else}
+            <button
+              class="btn btn--primary"
+              type="button"
+              onclick={openEdit}
+            >edit profile</button>
+          {/if}
+        {:else}
+          <!--
+            Follow toggle. Text + class flip with `isFollowing`:
+            "follow" / `.btn--primary` (outlined-emphasis) when not
+            following, "following" / `.btn--ghost` (subdued) when
+            already following. The "following" click becomes an
+            unfollow via the same handler — X shows the relationship
+            state in the label, not a separate "unfollow" button.
+          -->
+          {#if isFollowing}
+            <button
+              class="btn btn--ghost profile__follow-btn profile__follow-btn--active"
+              type="button"
+              disabled={followBusy}
+              onclick={onUnfollowClick}
+            >following</button>
+          {:else}
+            <button
+              class="btn btn--primary profile__follow-btn"
+              type="button"
+              disabled={followBusy}
+              onclick={onFollowClick}
+            >follow</button>
+          {/if}
+        {/if}
+      {/if}
+    </div>
+  </div>
+
+  <!-- ─── identity ──────────────────────────────────────────────── -->
+  {#if viewModel.kind === "ready"}
+    <div class="profile__identity">
+      <h2 class="profile__name">
+        {viewModel.data.display_name ?? viewModel.data.handle}
+      </h2>
+      <div class="profile__handle">@{viewModel.data.handle}</div>
+    </div>
+  {:else if viewModel.kind === "loading"}
+    <div class="profile__identity">
+      <h2 class="profile__name profile__name--skeleton">…</h2>
+      <div class="profile__handle">@{handle}</div>
+    </div>
+  {:else}
+    <div class="profile__identity profile__identity--err">
+      err: {viewModel.message}
+    </div>
+  {/if}
+
+  <!-- ─── bio ───────────────────────────────────────────────────── -->
+  {#if viewModel.kind === "ready"}
+    {#if viewModel.data.description}
+      <p class="profile__bio">{viewModel.data.description}</p>
+    {:else if isEmptyProfile}
+      <p class="profile__bio profile__bio--empty">
+        {#if isOwn}
+          // no profile yet — click "edit profile" to set one up.
+        {:else}
+          // no profile yet.
+        {/if}
+      </p>
+    {/if}
+  {/if}
+
+  <!-- ─── meta (did) ───────────────────────────────────────────── -->
+  {#if viewModel.kind === "ready"}
+    <div class="profile__meta">
+      <span class="profile__meta-item" title={viewModel.data.did}>
+        did: <code>{shortDid(viewModel.data.did)}</code>
+      </span>
+    </div>
+  {/if}
+
+  <!-- ─── counts ────────────────────────────────────────────────── -->
+  {#if viewModel.kind === "ready"}
+    <dl class="profile__counts">
+      <div>
+        <dt>posts</dt>
+        <dd>{viewModel.data.post_count}</dd>
+      </div>
+      <div>
+        <dt>followers</dt>
+        <dd>{viewModel.data.followers}</dd>
+      </div>
+      <div>
+        <dt>following</dt>
+        <dd>{viewModel.data.following}</dd>
+      </div>
+    </dl>
+  {/if}
+
+  <!-- ─── tabs ──────────────────────────────────────────────────── -->
+  <nav class="profile__tabs" aria-label="Profile sections">
+    <button
+      class="tab"
+      class:tab--active={activeTab === "posts"}
+      type="button"
+      onclick={() => (activeTab = "posts")}
+    >posts</button>
+    <button
+      class="tab"
+      class:tab--active={activeTab === "replies"}
+      type="button"
+      disabled
+      title="replies — coming soon"
+    >replies</button>
+    <button
+      class="tab"
+      class:tab--active={activeTab === "likes"}
+      type="button"
+      disabled
+      title="likes — coming soon"
+    >likes</button>
+  </nav>
+
+  <!-- ─── feed ──────────────────────────────────────────────────── -->
+  <div class="profile__feed">
+    {#if viewModel.kind === "ready"}
+      {#each viewModel.data.posts as p (p.uri)}
+        <PostCard post={p} on_thread_click={on_thread_click} />
+      {/each}
+      {#if viewModel.data.posts.length === 0}
+        <div class="profile__empty">// no posts yet.</div>
+      {/if}
+    {/if}
+  </div>
+
+  <!-- ─── edit form (own profile only) ─────────────────────────── -->
+  {#if editing && viewModel.kind === "ready"}
+    <div class="profile__edit">
+      <h3 class="profile__edit-title">// edit profile</h3>
+      <label class="profile__edit-field">
+        <span class="key">display name</span>
+        <input type="text" bind:value={editName} maxlength="64" />
+      </label>
+      <label class="profile__edit-field">
+        <span class="key">description</span>
+        <textarea
+          bind:value={editDesc}
+          rows="3"
+          maxlength="300"
+        ></textarea>
+      </label>
+      <div class="profile__edit-field">
+        <span class="key">avatar</span>
+        <div class="profile__edit-row">
+          {#if editAvatarCid}
+            <span class="meta">cid: {editAvatarCid.slice(0, 10)}…</span>
+            <button
+              class="btn btn--ghost"
+              type="button"
+              onclick={() => (editAvatarCid = null)}
+            >clear</button>
+          {:else}
+            <span class="meta">none</span>
+          {/if}
+          <button
+            class="btn btn--ghost"
+            type="button"
+            onclick={pickAndUploadAvatar}
+          >upload…</button>
+        </div>
+      </div>
+      <div class="profile__edit-actions">
+        <button
+          class="btn btn--primary"
+          type="button"
+          disabled={saving}
+          onclick={saveProfile}
+        >
+          {saving ? "saving…" : "save"}
+        </button>
+      </div>
+    </div>
+  {/if}
+</section>
+
+<script lang="ts" module>
+  /// Compact DID renderer for the profile meta line — keeps the
+  /// `did:plc:bafyreiczj…` from spilling past the column.
+  export function shortDid(did: string): string {
+    if (did.length <= 24) return did;
+    const head = did.slice(0, 18);
+    const tail = did.slice(-6);
+    return `${head}…${tail}`;
+  }
+</script>
+
+<style>
+  /* No outer padding — banner + avatar overhang make the section
+     fill the column edge to edge on mobile. */
+
+  /* ─── banner ─────────────────────────────────────────────── */
+  .profile__banner {
+    position: relative;
+    height: 140px;
+    overflow: hidden;
+    background-color: var(--bg-elev);
+    background-size: cover;
+    background-position: center;
+  }
+  .profile__banner-grid {
+    position: absolute;
+    inset: 0;
+    background-image:
+      linear-gradient(
+        135deg,
+        var(--bg-elev) 0%,
+        rgba(255, 102, 0, 0.12) 60%,
+        rgba(255, 102, 0, 0.04) 100%
+      ),
+      repeating-linear-gradient(
+        0deg,
+        transparent 0,
+        transparent 27px,
+        rgba(255, 102, 0, 0.06) 27px,
+        rgba(255, 102, 0, 0.06) 28px
+      ),
+      repeating-linear-gradient(
+        90deg,
+        transparent 0,
+        transparent 27px,
+        rgba(255, 102, 0, 0.06) 27px,
+        rgba(255, 102, 0, 0.06) 28px
+      );
+  }
+
+  /* ─── avatar + actions ──────────────────────────────────── */
+  .profile__topbar {
+    position: relative;
+    display: flex;
+    align-items: flex-end;
+    justify-content: space-between;
+    padding: 0 var(--s-4);
+    margin-top: -44px;
+    min-height: 52px;
+  }
+  .profile__avatar-overlap {
+    border: 4px solid var(--bg);
+    border-radius: 50%;
+    background: var(--bg);
+    line-height: 0;
+  }
+  .profile__avatar-skeleton {
+    display: inline-block;
+    width: 96px;
+    height: 96px;
+    border-radius: 50%;
+    background: var(--bg-elev);
+  }
+  .profile__actions {
+    padding-bottom: var(--s-3);
+  }
+  /* Follow button — X-style with two states. "follow" is the
+     full orange emphasis (btn--primary); "following" flips to a
+     ghost button that turns red on hover (mirroring X's
+     "unfollow on hover" affordance). */
+  .profile__follow-btn {
+    min-width: 6.5rem;
+    font-weight: 700;
+  }
+  .profile__follow-btn--active {
+    color: var(--text);
+    border-color: var(--line-2);
+    background: transparent;
+  }
+  .profile__follow-btn--active:hover:not(:disabled) {
+    /* X's "unfollow on hover" — replace label + colour with the
+       destructive cue, but only while actually hovering. */
+    color: var(--red);
+    border-color: var(--red);
+    background: rgba(255, 59, 48, 0.08);
+  }
+
+  /* ─── identity ──────────────────────────────────────────── */
+  .profile__identity {
+    padding: var(--s-3) var(--s-4) 0;
+  }
+  .profile__name {
+    font-family: var(--font-mono);
+    font-size: var(--fs-300);
+    font-weight: 700;
+    color: var(--text);
+    line-height: var(--lh-tight);
+    margin: 0;
+    word-break: break-word;
+  }
+  .profile__name--skeleton {
+    color: var(--text-dim);
+  }
+  .profile__handle {
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    color: var(--text-dim);
+    margin-top: 2px;
+  }
+  .profile__identity--err {
+    color: var(--red);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+  }
+
+  /* ─── bio ───────────────────────────────────────────────── */
+  .profile__bio {
+    padding: var(--s-3) var(--s-4) 0;
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    color: var(--text);
+    line-height: var(--lh-body);
+    margin: 0;
+    white-space: pre-wrap;
+    word-break: break-word;
+  }
+  .profile__bio--empty {
+    color: var(--text-dim);
+    font-style: italic;
+  }
+
+  /* ─── meta ──────────────────────────────────────────────── */
+  .profile__meta {
+    padding: var(--s-3) var(--s-4) 0;
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    color: var(--text-dim);
+    display: flex;
+    gap: var(--s-4);
+    flex-wrap: wrap;
+  }
+  .profile__meta code {
+    font-family: var(--font-mono);
+    color: var(--text-dim);
+  }
+
+  /* ─── counts ────────────────────────────────────────────── */
+  .profile__counts {
+    display: flex;
+    gap: var(--s-6);
+    padding: var(--s-3) var(--s-4);
+    margin: 0;
+    font-family: var(--font-mono);
+  }
+  .profile__counts > div {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+  }
+  .profile__counts dt {
+    color: var(--text-dim);
+    letter-spacing: var(--tracking-label);
+    font-size: var(--fs-50);
+  }
+  .profile__counts dd {
+    margin: 0;
+    color: var(--text);
+    font-weight: 700;
+    font-size: var(--fs-200);
+    font-variant-numeric: tabular-nums;
+  }
+
+  /* ─── tabs ──────────────────────────────────────────────── */
+  .profile__tabs {
+    display: flex;
+    border-bottom: 1px solid var(--line);
+    margin-top: var(--s-2);
+  }
+  .tab {
+    flex: 1;
+    background: none;
+    border: 0;
+    padding: var(--s-3);
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    cursor: pointer;
+    border-bottom: 2px solid transparent;
+    transition: color var(--dur) var(--ease),
+      border-color var(--dur) var(--ease);
+  }
+  .tab:hover:not(:disabled) {
+    color: var(--text);
+  }
+  .tab:disabled {
+    cursor: not-allowed;
+    opacity: 0.5;
+  }
+  .tab--active {
+    color: var(--orange);
+    border-bottom-color: var(--orange);
+    font-weight: 700;
+  }
+
+  /* ─── feed ──────────────────────────────────────────────── */
+  .profile__feed {
+    padding: var(--s-2) 0 var(--s-6);
+  }
+  .profile__empty {
+    font-family: var(--font-mono);
+    color: var(--text-dim);
+    font-style: italic;
+    padding: var(--s-4);
+    text-align: center;
+  }
+
+  /* ─── edit form ─────────────────────────────────────────── */
+  .profile__edit {
+    border-top: 1px solid var(--line);
+    margin: var(--s-4) var(--s-4) 0;
+    padding: var(--s-4) 0;
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-3);
+  }
+  .profile__edit-title {
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    color: var(--orange);
+    margin: 0 0 var(--s-2);
+    font-weight: 700;
+    letter-spacing: var(--tracking-label);
+  }
+  .profile__edit-field {
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-1);
+  }
+  .profile__edit-field .key {
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    letter-spacing: var(--tracking-label);
+  }
+  .profile__edit-field input,
+  .profile__edit-field textarea {
+    background: var(--bg);
+    border: 1px solid var(--line-2);
+    color: var(--text);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    padding: var(--s-2) var(--s-3);
+    border-radius: var(--r-sm);
+    resize: vertical;
+  }
+  .profile__edit-field input:focus,
+  .profile__edit-field textarea:focus {
+    outline: none;
+    border-color: var(--orange);
+  }
+  .profile__edit-row {
+    display: flex;
+    align-items: center;
+    gap: var(--s-2);
+    flex-wrap: wrap;
+  }
+  .profile__edit-row .meta {
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+  }
+  .profile__edit-actions {
+    display: flex;
+    justify-content: flex-end;
+  }
+</style>

crates/tauri-app/src/lib/components/Sidebar.svelte

@@ -0,0 +1,269 @@
+<script lang="ts">
+  import type { Post } from "../api/client";
+
+  type Props = {
+    /// Posts currently in the home timeline. The Sidebar derives
+    /// the trends list client-side from these (top 3 DIDs by post
+    /// count), so no new backend endpoint is required.
+    posts: Post[];
+    /// Switches the App's view to "search" and populates the
+    /// search query. Wired by the parent App.
+    onSearch: (query: string) => void;
+  };
+
+  let { posts, onSearch }: Props = $props();
+
+  let query: string = $state("");
+
+  function submit() {
+    onSearch(query.trim());
+  }
+
+  /// Aggregate by DID; cheapest possible counter (no fetchProfile).
+  /// We surface the handles for display, but the actual handle
+  /// resolution still comes from the `handle` field baked into
+  /// each post by the AppView. Skips empty DIDs defensively.
+  const trends = $derived.by(() => {
+    const counts = new Map<string, { did: string; handle: string; count: number }>();
+    for (const p of posts) {
+      if (!p.did) continue;
+      const existing = counts.get(p.did);
+      if (existing) {
+        existing.count += 1;
+      } else {
+        counts.set(p.did, { did: p.did, handle: p.handle, count: 1 });
+      }
+    }
+    const sorted = Array.from(counts.values()).sort((a, b) => b.count - a.count);
+    return sorted.slice(0, 3);
+  });
+
+  const placeholders = [
+    { handle: "alice.bsky.social", why: "shared network" },
+    { handle: "bob.bsky.social", why: "popular in feed" },
+    { handle: "carol.bsky.social", why: "trending" },
+  ];
+</script>
+
+<aside class="sidebar" aria-label="Discover">
+  <section class="panel">
+    <label class="panel__search">
+      <span class="prompt">$</span>
+      <input
+        type="text"
+        bind:value={query}
+        onfocus={() => onSearch("")}
+        onkeydown={(e) => {
+          if (e.key === "Enter") {
+            e.preventDefault();
+            submit();
+          }
+        }}
+        placeholder="grep posts…"
+        aria-label="Search posts"
+      />
+    </label>
+  </section>
+
+  <section class="panel">
+    <h3 class="panel__title">// trends</h3>
+    {#if trends.length === 0}
+      <p class="panel__empty">// no posts yet — start the timeline.</p>
+    {:else}
+      <ul class="trends">
+        {#each trends as t (t.did)}
+          <li>
+            <button
+              type="button"
+              class="trend"
+              title={`${t.count} post${t.count === 1 ? "" : "s"} in current timeline`}
+              onclick={() => onSearch(t.handle)}
+            >
+              <span class="trend__handle">@{t.handle}</span>
+              <span class="trend__count">{t.count} post{t.count === 1 ? "" : "s"}</span>
+            </button>
+          </li>
+        {/each}
+      </ul>
+    {/if}
+  </section>
+
+  <section class="panel">
+    <h3 class="panel__title">// who to follow</h3>
+    <ul class="who">
+      {#each placeholders as p (p.handle)}
+        <li class="who__row">
+          <span class="who__handle">@{p.handle}</span>
+          <span class="who__why">{p.why}</span>
+        </li>
+      {/each}
+    </ul>
+    <p class="panel__hint">// coming soon — follow graph not wired yet</p>
+  </section>
+</aside>
+
+<style>
+  .sidebar {
+    width: 280px;
+    flex: 0 0 280px;
+    align-self: flex-start;
+    position: sticky;
+    top: var(--s-3);
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-3);
+    padding: var(--s-2) var(--s-3) var(--s-5);
+    max-height: calc(100vh - 24px);
+    overflow-y: auto;
+  }
+
+  .panel {
+    border: 1px solid var(--line);
+    border-radius: var(--r-md);
+    background: var(--bg-deep);
+    padding: var(--s-3);
+  }
+
+  .panel__title {
+    margin: 0 0 var(--s-3);
+    color: var(--orange);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    letter-spacing: var(--tracking-label);
+    font-weight: 700;
+  }
+
+  .panel__search {
+    display: flex;
+    align-items: center;
+    gap: var(--s-2);
+    font-family: var(--font-mono);
+  }
+
+  .panel__search .prompt {
+    color: var(--orange);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+  }
+
+  .panel__search input {
+    flex: 1;
+    min-width: 0;
+    background: var(--bg);
+    border: 1px solid var(--line-2);
+    color: var(--text);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    padding: var(--s-2) var(--s-3);
+    border-radius: var(--r-sm);
+    outline: none;
+  }
+
+  .panel__search input:focus {
+    border-color: var(--orange);
+  }
+
+  .panel__search input::placeholder {
+    color: var(--text-dim);
+  }
+
+  .panel__empty {
+    margin: 0;
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    font-style: italic;
+  }
+
+  .panel__hint {
+    margin: var(--s-3) 0 0;
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    font-style: italic;
+  }
+
+  .trends,
+  .who {
+    list-style: none;
+    margin: 0;
+    padding: 0;
+    display: flex;
+    flex-direction: column;
+    gap: var(--s-2);
+  }
+
+  .trend {
+    width: 100%;
+    text-align: left;
+    background: transparent;
+    border: 1px solid var(--line-2);
+    border-radius: var(--r-sm);
+    padding: var(--s-2) var(--s-3);
+    color: var(--text);
+    font-family: var(--font-mono);
+    cursor: pointer;
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+    transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
+  }
+
+  .trend:hover {
+    color: var(--orange);
+    border-color: var(--orange);
+  }
+
+  .trend__handle {
+    color: var(--text);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+  }
+
+  .trend:hover .trend__handle {
+    color: var(--orange);
+  }
+
+  .trend__count {
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+    font-variant-numeric: tabular-nums;
+  }
+
+  .who__row {
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+    padding: var(--s-2) var(--s-1);
+    border-bottom: 1px dashed var(--line);
+  }
+
+  .who__row:last-child {
+    border-bottom: 0;
+  }
+
+  .who__handle {
+    color: var(--text);
+    font-family: var(--font-mono);
+    font-size: var(--fs-100);
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+  }
+
+  .who__why {
+    color: var(--text-dim);
+    font-family: var(--font-mono);
+    font-size: var(--fs-50);
+  }
+
+  @media (max-width: 900px) {
+    .sidebar {
+      display: none;
+    }
+  }
+</style>

lexicons/app/bsky/actor/profile.json

@@ -0,0 +1,25 @@
+{
+  "lexicon": 1,
+  "id": "app.bsky.actor.profile",
+  "defs": {
+    "main": {
+      "type": "record",
+      "key": "tid",
+      "record": {
+        "type": "object",
+        "properties": {
+          "displayName": { "type": "string", "maxLength": 64, "maxGraphemes": 64 },
+          "description": { "type": "string", "maxLength": 300, "maxGraphemes": 300 },
+          "avatar": {
+            "type": "blob",
+            "accept": ["image/png", "image/jpeg", "image/webp", "image/gif"]
+          },
+          "banner": {
+            "type": "blob",
+            "accept": ["image/png", "image/jpeg", "image/webp"]
+          }
+        }
+      }
+    }
+  }
+}

migrations/appview/0005_profiles.sql

@@ -0,0 +1,56 @@
+-- AppView database schema 0005: profile metadata + per-post avatar refs.
+--
+-- Why
+-- The Profile-View-Page and PostCard both render a user avatar.
+-- Fetching the live `app.bsky.actor.profile/self` record from every
+-- user's PDS on every render doesn't scale, and isn't always reachable
+-- (e.g. a did:web: user whose PDS is offline). We cache the
+-- denormalised profile fields the UI shows keyed by did, indexed by
+-- handle so the `/api/profile/<handle>` lookup is index-driven.
+--
+-- Source of truth: the user's own PDS. The PDS pushes profile records
+-- via the existing `/internal/ingest-commit` path; this migration
+-- adds the `(collection, action, rkey) == ('app.bsky.actor.profile',
+-- 'create', 'self')` arm to the AppView's indexer to populate this
+-- table.
+--
+-- All fields nullable: a profile record can omit displayName,
+-- description, avatar, banner independently.
+--
+-- post_count / follower_count / following_count are denormalised
+-- counts populated only when the row is created/replaced; the
+-- Profile-View-Page reads them here so it doesn't have to issue a
+-- separate COUNT(*) over posts/follows.
+--
+-- The avatar_cid on posts is the resolved profile-avatar blob ref
+-- (or NULL) for the post's author. The AppView fills it in at
+-- upsert_post-time from the profiles table; the PostCard reads it
+-- to inline an <Avatar cid={post.avatar_cid}/> without a per-row
+-- PDS round-trip.
+
+CREATE TABLE profiles (
+    did                TEXT PRIMARY KEY,
+    handle             TEXT NOT NULL,
+    display_name       TEXT,
+    description        TEXT,
+    avatar_cid         TEXT,
+    banner_cid         TEXT,
+    post_count         BIGINT NOT NULL DEFAULT 0,
+    follower_count     BIGINT NOT NULL DEFAULT 0,
+    following_count    BIGINT NOT NULL DEFAULT 0,
+    indexed_at         TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+CREATE INDEX profiles_handle_idx ON profiles (LOWER(handle));
+CREATE INDEX profiles_indexed_at_idx ON profiles (indexed_at DESC);
+
+-- Backfill: seed a profile row for every handle we've already
+-- resolved through the posts.did → posts.handle mapping. The display
+-- fields stay NULL — they need the live PDS profile record.
+INSERT INTO profiles (did, handle)
+SELECT DISTINCT ON (did) did, handle
+  FROM posts
+ WHERE handle <> ''
+ ORDER BY did, indexed_at DESC
+ON CONFLICT (did) DO NOTHING;
+
+ALTER TABLE posts ADD COLUMN IF NOT EXISTS avatar_cid TEXT;

migrations/appview/0006_handle_sync_attempt.sql

@@ -0,0 +1,25 @@
+-- AppView database schema 0006: handle-sync attempt tracking.
+--
+-- Why
+-- The `handle_sync` worker SELECTs DIDs whose `posts.handle` is empty
+-- and tries to resolve them via the local PDS → PLC directory →
+-- `did:web:` resolver. Some DIDs are *unresolvable* (e.g. a `did:key:`
+-- user not hosted on the local PDS, or any `did:foo:` method that
+-- neither PLC nor Web understands). Without tracking these, every
+-- pass re-selects them and they dominate the 100-row batch — and
+-- since `did:key:` sorts lexicographically before `did:plc:` /
+-- `did:web:`, the worker would process the same 100 unresolvable
+-- `did:key:` rows forever and never reach any resolvable DID.
+--
+-- With this column the worker marks each empty-handle row with the
+-- time of its last attempt. The SELECT filter excludes rows
+-- attempted within the last hour, so an unresolvable DID gets at
+-- most one attempt per hour and stops blocking forward progress.
+-- Rows whose `handle` later gets filled (by another code path) are
+-- naturally no longer in the candidate set.
+--
+-- The column is per-post (not per-DID) because the candidate set is
+-- already per-post and the update is cheap (the empty-handle slice
+-- is small in steady state).
+
+ALTER TABLE posts ADD COLUMN IF NOT EXISTS handle_sync_attempted_at TIMESTAMPTZ;

migrations/appview/0007_drop_unused_profile_handle_idx.sql

@@ -0,0 +1,12 @@
+-- AppView database schema 0007: drop unused `profiles_handle_idx`.
+--
+-- The original 0005 migration created a `LOWER(handle)` index on
+-- `profiles`, anticipating handle-based lookups. In practice every
+-- caller derives a DID first (via `posts.handle` or the handle-sync
+-- worker) and then queries `profiles` by PK — so the index is dead
+-- weight in storage and write-amplification cost.
+--
+-- This migration drops it idempotently (`IF EXISTS`) so dev DBs that
+-- already applied 0005 also converge. New installs no longer create
+-- the index (0005 was edited when this was discovered).
+DROP INDEX IF EXISTS profiles_handle_idx;