feat(fs): delta savings in sync stats + exclude interrupted-sync temp files

- Add SyncStats.file_bytes: total uncompressed size of transferred files;
  lets CLI compute CDC delta savings (e.g. "1.2 MB file bytes, 45 KB wire, 96% savings")
- Update cmd_sync summary to show "X file bytes (Y wire, Z% delta savings)" when
  delta savings are non-trivial; falls back to plain "X bytes" for cold copies
- Exclude *.tmp.clawsync from FsManifest::build() unconditionally so leftover
  temp files from interrupted syncs never appear in manifests or get transferred
- Add manifest unit test confirming temp file exclusion

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

crates/clawsync-cli/src/main.rs

@@ -1215,12 +1215,23 @@ async fn cmd_sync(
             mods.len(),
             rems.len()
         );
+    } else {
+        let wire = stats.bytes_transferred;
+        let files = stats.file_bytes;
+        if files > 0 && wire < files {
+            let savings_pct = 100u64 - wire * 100 / files;
+            println!(
+                "Sync complete: {} added, {} modified, {} removed, {} file bytes ({} wire, {}% delta savings).",
+                stats.files_added, stats.files_modified, stats.files_removed,
+                files, wire, savings_pct
+            );
         } else {
             println!(
                 "Sync complete: {} added, {} modified, {} removed, {} bytes.",
-            stats.files_added, stats.files_modified, stats.files_removed, stats.bytes_transferred
+                stats.files_added, stats.files_modified, stats.files_removed, wire
             );
         }
+    }
     Ok(())
 }
 

crates/clawsync-fs/src/manifest.rs

@@ -60,6 +60,12 @@ impl FsManifest {
             if !rel.is_empty() && excludes.is_match(&rel) {
                 continue;
             }
+            // Always exclude clawsync temp files regardless of caller excludes.
+            // These are leftover from interrupted syncs and must never appear
+            // in manifests or be transferred to peers.
+            if rel.ends_with(".tmp.clawsync") {
+                continue;
+            }
             candidates.push((abs, rel));
         }
 
@@ -192,4 +198,18 @@ mod tests {
             .collect();
         assert_eq!(paths, vec!["a.bin", "m.bin", "z.bin"]);
     }
+
+    #[test]
+    fn build_always_excludes_clawsync_temp_files() {
+        let dir = TempDir::new().unwrap();
+        fs::write(dir.path().join("real.bin"), b"real content").unwrap();
+        // Simulate a leftover temp file from an interrupted sync.
+        fs::write(dir.path().join("real.tmp.clawsync"), b"incomplete").unwrap();
+        fs::write(dir.path().join("other.bin.tmp.clawsync"), b"also incomplete").unwrap();
+
+        let manifest = FsManifest::build(dir.path(), &empty_excludes()).unwrap();
+
+        let paths: Vec<&str> = manifest.entries.iter().map(|e| e.rel_path.as_str()).collect();
+        assert_eq!(paths, vec!["real.bin"], "temp files must be excluded from manifest");
+    }
 }

crates/clawsync-fs/src/session.rs

@@ -59,7 +59,14 @@ pub struct SyncStats {
     pub files_added: u32,
     pub files_modified: u32,
     pub files_removed: u32,
+    /// Actual bytes sent over the wire (compressed literal chunks only).
     pub bytes_transferred: u64,
+    /// Total uncompressed size of every file that was added or modified.
+    ///
+    /// Comparing `file_bytes` to `bytes_transferred` shows the CDC delta
+    /// savings (e.g. 96% of file_bytes skipped because blocks already exist
+    /// on the server).  Zero when no files are transferred.
+    pub file_bytes: u64,
     /// Populated only in dry-run mode: paths that would be added.
     pub would_add: Option<Vec<String>>,
     /// Populated only in dry-run mode: paths that would be modified.
@@ -149,6 +156,7 @@ impl FsSyncClient {
                     files_modified: would_modify.len() as u32,
                     files_removed: would_remove.len() as u32,
                     bytes_transferred: 0,
+                    file_bytes: 0,
                     would_add: Some(would_add),
                     would_modify: Some(would_modify),
                     would_remove: Some(would_remove),
@@ -197,6 +205,13 @@ impl FsSyncClient {
         // The semaphore (W=16) limits in-flight FsCdcData messages.
 
         let total = needed_files.len();
+        // Sum up the uncompressed sizes of files we'll transfer (from the manifest).
+        // This lets us report delta savings alongside the wire byte count.
+        let file_bytes: u64 = needed_files
+            .iter()
+            .filter_map(|f| manifest.get(&f.path))
+            .map(|e| e.size)
+            .sum();
         let progress_tx = self.progress_tx.take();
         if let Some(tx) = &progress_tx {
             let _ = tx.send(ProgressEvent::TotalFiles(total));
@@ -297,6 +312,7 @@ impl FsSyncClient {
                 files_modified,
                 files_removed,
                 bytes_transferred,
+                file_bytes,
                 ..Default::default()
             },
             other => {