maarcadetweet: initial commit

AT Protocol PDS + AppView + Tauri Desktop Client, 160-char post limit. - PDS (Rust + axum + sqlx) - Auth: createAccount, createSession, refreshSession - Records: createRecord, deleteRecord (race-safe via SELECT FOR UPDATE) - Feed: feed.like.create, feed.repost.create - Sync: getRepo, getBlocks, getLatestCommit, getRecord (with MST proof), listRepos - Identity: resolveHandle - MST: spec-conformant (at-mst crate, 27 tests) - Repo: signed commits, TID counter (monotonic, 4096 wrap safe) - AppView (Rust + axum + sqlx) - Jetstream consumer (WebSocket, exponential backoff, 38k+ events indexed) - REST API: timeline/home (graph-aware), profile, search, post (with thread hydration) - Handle-sync worker (did:plc + did:web) - JSONB embed storage + thread columns (migration 0003) - Like/repost counter cache (migration 0004) - Tauri 2 + Svelte 5 Desktop Client - System tray (Show/Compose/Quit menu) - OS notifications (tauri-plugin-notification) - Auto-update (tauri-plugin-updater, placeholder endpoint) - Window-state (tauri-plugin-window-state) - 160-char compose with live counter - Image/Link embed rendering - LocalStorage-persisted like state - Timeline with poll (prepend new posts) - Custom TitleBar (transparent, no decorations) - Orange/IBM Plex Mono maarcade design Tests: 231 Rust + 9 vitest = 240 passed.
2026-07-05 20:01:31 +02:00
commit c586fd39c9
134 changed files with 35279 additions and 0 deletions
@@ -0,0 +1,100 @@
+use anyhow::{anyhow, Result};
+
+use at_crypto::cid::sha256;
+
+pub const DEFAULT_FANOUT: usize = 8;
+
+pub fn max_layer_for_fanout(fanout: usize) -> usize {
+    if fanout <= 1 {
+        return 0;
+    }
+    (usize::ilog2(fanout) as usize).saturating_sub(1)
+}
+
+pub fn count_leading_zero_bits(hash: &[u8]) -> usize {
+    let mut count = 0usize;
+    for &byte in hash {
+        if byte == 0 {
+            count += 8;
+        } else {
+            count += byte.leading_zeros() as usize;
+            break;
+        }
+    }
+    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);
+    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 decode_key(encoded: &str) -> Result<Vec<u8>> {
+    use base64::Engine;
+    base64::engine::general_purpose::URL_SAFE_NO_PAD
+        .decode(encoded.as_bytes())
+        .map_err(|e| anyhow!("invalid base64url key `{encoded}`: {e}"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn max_layer_for_fanout_8() {
+        assert_eq!(max_layer_for_fanout(8), 2);
+    }
+
+    #[test]
+    fn max_layer_for_fanout_16() {
+        assert_eq!(max_layer_for_fanout(16), 3);
+    }
+
+    #[test]
+    fn max_layer_for_fanout_1() {
+        assert_eq!(max_layer_for_fanout(1), 0);
+    }
+
+    #[test]
+    fn count_leading_zeros_all_zero() {
+        let h = [0u8; 32];
+        assert_eq!(count_leading_zero_bits(&h), 256);
+    }
+
+    #[test]
+    fn count_leading_zeros_one_bit() {
+        let mut h = [0u8; 32];
+        h[0] = 0b0000_0001;
+        assert_eq!(count_leading_zero_bits(&h), 7);
+    }
+
+    #[test]
+    fn count_leading_zeros_one_nibble() {
+        let mut h = [0u8; 32];
+        h[0] = 0x0f;
+        assert_eq!(count_leading_zero_bits(&h), 4);
+    }
+
+    #[test]
+    fn count_leading_zeros_byte_boundary() {
+        let mut h = [0u8; 32];
+        h[2] = 0x80;
+        assert_eq!(count_leading_zero_bits(&h), 16);
+        let mut h = [0u8; 32];
+        h[2] = 0x01;
+        assert_eq!(count_leading_zero_bits(&h), 23);
+    }
+
+    #[test]
+    fn key_to_layer_zero_layer() {
+        let layer = key_to_layer("com.example.foo/abc", 8);
+        assert!(layer <= 2);
+    }
+}