feat(node): persistent index cache, visible scan progress, adaptive reconcile, and delta sync

Indexer performance work, in four parts:

- Persistent (path, size, mtime) -> hash cache (indexer/cache.py) so a node
  restart no longer re-hashes every file — measured at 23 minutes for a
  114 GB library on a slow disk before this, near-instant after. Hashing
  is deliberately kept sequential (max_workers=1): it was never actually
  concurrent despite the pool size, and two interleaved reads seek-thrash
  a spinning disk instead of going faster.

- Byte-based scan progress (IndexProgress), surfaced via the loopback
  index-status route, the handshake ack, and a periodic INDEX_PROGRESS
  push to connected peers — drives a progress bar in the Create Group
  wizard and "add a directory" in Settings, and an animated presence dot.
  Guaranteed to settle back to idle via try/finally and a final push on
  the scanning->false transition.

- The reconcile backstop's directory walks now run in the executor
  instead of blocking the daemon's event loop; its interval defaults to
  10 min (was 60s) with adaptive backoff to 2h when nothing changes,
  reset on a real change or a peer connecting, and is now a per-group
  operator setting (signed op + group Settings UI).

- INDEX_DELTA wired up (protocol support existed, nothing called it):
  _on_index_change now sends additions/deletions instead of rebuilding
  the full entries list, coalesced over a short window so a burst of
  file events produces one push, and the hub swarm registration for
  public groups only (re-)registers newly added hashes.

Also fixes several bugs found while testing the above against real
libraries (a 114 GB and a 100+ GB group on a USB HDD):

- /api/reload blocked until the reload — including a brand-new group's
  full initial scan — finished, which the Electron bridge's fixed 30s
  call timeout turned into a hard failure on any real library. The route
  now fires the reload without waiting (ops.start_reload), matching
  add_root/remove_root's existing pattern; the wizard's own step order
  was fixed to wait for the group to actually appear hosted before the
  steps that need it (extra roots, GEK), with retries for the residual
  race between that and the daemon's own bookkeeping.
- transport.js's hand-rolled msgpack codec had no case for uint64/int64
  (0xcf/0xd3) and crashed decoding any message containing one — hit by
  IndexProgress.scanned_bytes/total_bytes for any group over ~4.3 GB.
  Verified against real msgpack-encoded bytes from the Python side.
- chat_hist_resp, and this change's own index_progress and
  set_scan_settings_ack pushes, were not routed by message type and
  could be handed to an unrelated pending request by the transport's
  "oldest pending" fallback, stalling it until its own 30s timeout and
  corrupting whatever received the wrong reply in its place.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016SF6RKNBKg9qejmoMJ9ybA

1 files changed, 50 insertions, 1 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/ui/app.py b/packages/meshbay-node/src/meshbay_node/ui/app.py
index b505f25..d5b3f94 100644
--- a/packages/meshbay-node/src/meshbay_node/ui/app.py
+++ b/packages/meshbay-node/src/meshbay_node/ui/app.py
@@ -26,6 +26,7 @@ from fastapi.responses import HTMLResponse, JSONResponse
 from meshbay_node import __version__
 from meshbay_node import ops
 from meshbay_node.config import DEFAULT_CONFIG_PATH
+from meshbay_node.indexer.indexer import DirectoryIndexer
 from meshbay_common.crypto import generate_gek, wrap_gek_aes
 from meshbay_common.join import ROLE_MEMBER, ROLE_OPERATOR
 
@@ -319,6 +320,39 @@ def create_ui_app(state: dict) -> FastAPI:
             asyncio.ensure_future(reload_fn())
         return result
 
+    # asyncio.ensure_future above schedules the reload (and whatever initial
+    # scan it triggers) on the daemon's own event loop — it has no link to
+    # this HTTP request or to any browser tab. Closing the client that made
+    # this call does not cancel it: the scan is the node's own background
+    # work, not something borrowed from the request that started it.
+
+    @app.get("/api/groups/{group_id}/index-status")
+    async def index_status(group_id: str):
+        """
+        Polled by the Create Group wizard and by "add a directory" in
+        Settings — the same source either way, since both just start a scan
+        on this group's indexer. `current_dir` is a basename only, and is
+        never sent over MNP (see IndexProgress in indexer.py) — this route
+        is loopback-only, for the operator's own screen.
+
+        Reads state["indexers"] rather than groups_ctx: a brand-new group is
+        registered there before its (possibly long) initial scan runs, but
+        is only added to groups_ctx once that scan finishes (it is not yet
+        authorized for member connections either way — see _reload_config)
+        — this is precisely the window the wizard needs to watch.
+        """
+        indexer = state.get("indexers", {}).get(group_id)
+        progress = indexer.progress if indexer else None
+        if progress is None:
+            return {"scanning": False, "scanned_bytes": 0, "total_bytes": 0,
+                    "current_dir": ""}
+        return {
+            "scanning": progress.scanning,
+            "scanned_bytes": progress.scanned_bytes,
+            "total_bytes": progress.total_bytes,
+            "current_dir": progress.current_dir,
+        }
+
     # ── Upload toggle (operator only, localhost) ─────────────────────────
 
     @app.put("/api/groups/{group_id}/member-upload")
@@ -327,11 +361,26 @@ def create_ui_app(state: dict) -> FastAPI:
             state, group_id, bool(payload.get("allowed", False)),
         ))
 
+    # ── Scan settings (operator only, localhost) ──────────────────────────
+
+    @app.put("/api/groups/{group_id}/scan-settings")
+    async def set_scan_settings(group_id: str, payload: dict):
+        return await _op(lambda: ops.set_scan_settings(
+            state, group_id,
+            float(payload.get("reconcile_interval_secs",
+                              DirectoryIndexer.DEFAULT_RECONCILE_SECS)),
+            float(payload.get("debounce_secs",
+                              DirectoryIndexer.DEFAULT_DEBOUNCE_SECS)),
+        ))
+
     # ── Reload config ────────────────────────────────────────────────────
 
     @app.post("/api/reload")
     async def reload_config():
-        return await _op(lambda: ops.reload_config(state))
+        # start_reload, not reload_config: this must return before a
+        # brand-new group's synchronous initial scan finishes (minutes, not
+        # seconds, on a real library) — see ops.start_reload for why.
+        return await _op(lambda: ops.start_reload(state))
 
     # ── Chat endpoints ───────────────────────────────────────────────────────