Implement persistent manifest cache and parallel file scanning

crates/filesync/Cargo.toml

@@ -19,7 +19,9 @@ crossbeam-channel = { workspace = true }
 parking_lot       = { workspace = true }
 log               = { workspace = true }
 bincode           = "1"
-blake3            = "1"
+blake3            = { version = "1", features = ["mmap", "rayon"] }
+jwalk             = "0.8"
+num_cpus          = "1"
 lz4_flex          = "0.11"
 rayon             = "1"
 walkdir           = "2"

crates/filesync/src/bundler.rs

@@ -153,18 +153,11 @@ fn stream_large_file(
     );
 
     let hash_start = std::time::Instant::now();
+    // Unified tiered digest (mmap for big files, streaming otherwise);
+    // the chunk protocol below is unchanged.
     let final_hash: [u8; 32] = {
-        let mut hasher = blake3::Hasher::new();
-        let mut f = std::fs::File::open(&full)?;
-        let mut buf = vec![0u8; 64 * 1024];
-        loop {
-            let n = f.read(&mut buf)?;
-            if n == 0 {
-                break;
-            }
-            hasher.update(&buf[..n]);
-        }
-        hasher.finalize().into()
+        let (_, h) = crate::manifest::hash_file_tiered(&full)?;
+        h
     };
     debug!(
         "bundler: large file {:?} hash computed in {}ms",

crates/filesync/src/lib.rs

@@ -7,6 +7,7 @@ pub mod gui;
 pub mod known_hosts;
 pub mod ledger;
 pub mod manifest;
+pub mod manifest_cache;
 pub mod protocol;
 pub mod server;
 pub mod suspend_detector;
@@ -17,6 +18,7 @@ pub mod watcher;
 pub use app::FileSyncApp;
 pub use known_hosts::{ClientStatus, KnownClient, KnownClients, KnownServer, KnownServers};
 pub use ledger::{DeletionLedger, Tombstone, DELETION_LEDGER_TTL_MS};
+pub use manifest_cache::{CachedEntry, ManifestCache, CACHE_MIN_AGE_MS};
 
 pub fn timestamp_id() -> u64 {
     use std::time::{SystemTime, UNIX_EPOCH};