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

4 files changed, 330 insertions, 50 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/indexer/__init__.py b/packages/meshbay-node/src/meshbay_node/indexer/__init__.py
index bb6231b..c92c730 100644
--- a/packages/meshbay-node/src/meshbay_node/indexer/__init__.py
+++ b/packages/meshbay-node/src/meshbay_node/indexer/__init__.py
@@ -1,5 +1,6 @@
 """Directory indexer and Mesh Group Index."""
 from .indexer import DirectoryIndexer
 from .group_index import GroupIndex
+from .cache import IndexCache
 
-__all__ = ["DirectoryIndexer", "GroupIndex"]
+__all__ = ["DirectoryIndexer", "GroupIndex", "IndexCache"]
diff --git a/packages/meshbay-node/src/meshbay_node/indexer/cache.py b/packages/meshbay-node/src/meshbay_node/indexer/cache.py
new file mode 100644
index 0000000..c26ddf1
--- /dev/null
+++ b/packages/meshbay-node/src/meshbay_node/indexer/cache.py
@@ -0,0 +1,95 @@
+"""
+MeshBay Node — persistent (path, size, mtime) -> hash cache, one per group.
+
+Without this, every node restart re-reads and re-hashes every file in every
+root, even when nothing changed — measured at 23 minutes for a 114 GB library
+on a USB hard drive. This cache lets a scan skip the read entirely for a file
+whose size and mtime still match what was hashed last time.
+
+It is a path-keyed accelerator only. The GroupIndex itself stays keyed by
+content hash (see indexer.py's note on why two identical files are one
+entry) — this cache never changes that, it only avoids recomputing a hash
+that has not changed.
+"""
+
+import logging
+from dataclasses import dataclass
+from pathlib import Path
+
+import aiosqlite
+
+log = logging.getLogger(__name__)
+
+_SCHEMA = """
+CREATE TABLE IF NOT EXISTS files (
+    path      TEXT PRIMARY KEY,
+    mtime     REAL NOT NULL,
+    size      INTEGER NOT NULL,
+    hash      TEXT NOT NULL,
+    type      TEXT NOT NULL,
+    added_at  INTEGER NOT NULL
+);
+"""
+
+
+@dataclass
+class CachedEntry:
+    hash: str
+    type: str
+    added_at: int
+
+
+class IndexCache:
+    """Async SQLite (path, size, mtime) -> hash cache for one group."""
+
+    def __init__(self, db_path: Path):
+        self._db_path = db_path
+        self._db: aiosqlite.Connection | None = None
+
+    async def open(self) -> None:
+        self._db_path.parent.mkdir(parents=True, exist_ok=True)
+        self._db = await aiosqlite.connect(str(self._db_path))
+        await self._db.executescript(_SCHEMA)
+        await self._db.commit()
+
+    async def close(self) -> None:
+        if self._db:
+            await self._db.close()
+            self._db = None
+
+    async def __aenter__(self):
+        await self.open()
+        return self
+
+    async def __aexit__(self, *_):
+        await self.close()
+
+    async def lookup(self, path: str, size: int, mtime: float) -> CachedEntry | None:
+        """
+        A cache hit requires an EXACT match on both size and mtime. A mtime
+        touched without a content change is a false negative (an unnecessary
+        rehash) — accepted, since the alternative (trusting a stale hash) is
+        a silent wrong answer instead of an occasional wasted read.
+        """
+        async with self._db.execute(
+                "SELECT hash, type, added_at FROM files "
+                "WHERE path = ? AND size = ? AND mtime = ?",
+                (path, size, mtime)) as cur:
+            row = await cur.fetchone()
+        return CachedEntry(hash=row[0], type=row[1], added_at=row[2]) if row else None
+
+    async def put(self, path: str, size: int, mtime: float, hash: str,
+                  type: str, added_at: int) -> None:
+        """
+        Written only once a file has been hashed in full — never partway
+        through — so a crash mid-hash leaves no stale/partial row behind: the
+        next scan simply finds no cache entry and hashes the file again.
+        """
+        await self._db.execute(
+            "INSERT INTO files (path, mtime, size, hash, type, added_at) "
+            "VALUES (?, ?, ?, ?, ?, ?) "
+            "ON CONFLICT(path) DO UPDATE SET "
+            "mtime = excluded.mtime, size = excluded.size, hash = excluded.hash, "
+            "type = excluded.type, added_at = excluded.added_at",
+            (path, mtime, size, hash, type, added_at))
+        await self._db.commit()
diff --git a/packages/meshbay-node/src/meshbay_node/indexer/group_index.py b/packages/meshbay-node/src/meshbay_node/indexer/group_index.py
index 5dbdc5d..ec98667 100644
--- a/packages/meshbay-node/src/meshbay_node/indexer/group_index.py
+++ b/packages/meshbay-node/src/meshbay_node/indexer/group_index.py
@@ -86,6 +86,23 @@ class GroupIndex:
     def count(self) -> int:
         return len(self._entries)
 
+    def entries_by_id(self) -> dict:
+        """A snapshot copy, for diff() to compare a later version against —
+        see daemon.py _on_index_change, the only caller."""
+        return dict(self._entries)
+
+    @classmethod
+    def _snapshot(cls, group_id: str, sk_node: Ed25519PrivateKey, gek: bytes | None,
+                  version: int, entries_by_id: dict) -> "GroupIndex":
+        """
+        A lightweight stand-in for diff()'s `previous` argument — never
+        serialized or sent anywhere, just a comparison point built from an
+        earlier entries_by_id() snapshot rather than a live GroupIndex.
+        """
+        idx = cls(group_id=group_id, sk_node=sk_node, gek=gek, version=version)
+        idx._entries = dict(entries_by_id)
+        return idx
+
     # ── Serialisation ─────────────────────────────────────────────────────────
 
     def serialize(self) -> bytes:
diff --git a/packages/meshbay-node/src/meshbay_node/indexer/indexer.py b/packages/meshbay-node/src/meshbay_node/indexer/indexer.py
index 482b556..b479f7e 100644
--- a/packages/meshbay-node/src/meshbay_node/indexer/indexer.py
+++ b/packages/meshbay-node/src/meshbay_node/indexer/indexer.py
@@ -26,6 +26,7 @@ import asyncio
 import logging
 import time
 from concurrent.futures import ThreadPoolExecutor
+from dataclasses import dataclass
 from pathlib import Path
 from typing import Callable, Awaitable
 
@@ -36,6 +37,7 @@ from watchdog.observers import Observer
 
 from meshbay_common.paths import fold, find_fold_collisions, long_path
 from meshbay_common.protocol import IndexEntry
+from meshbay_node.indexer.cache import IndexCache
 from meshbay_node.indexer.group_index import GroupIndex
 from meshbay_node.roots import Root, RootSet
 
@@ -75,6 +77,27 @@ def _is_indexable(path: Path) -> bool:
 _HASH_CHUNK = 8 * 1024 * 1024   # 8 MB streaming hash chunks
 
 
+@dataclass
+class IndexProgress:
+    """
+    A snapshot of "is this indexer mid-scan right now", for the status shown
+    to the operator (Create Group wizard, adding a directory) and pushed to
+    connected members (a presence dot, never anything more specific — see
+    daemon.py/webrtc_server.py). Reset per _scan_root() call rather than
+    accumulated across a group's roots: the consumers that matter always
+    watch exactly one root being scanned.
+
+    Mutated only from the asyncio loop thread (the hashing itself runs in an
+    executor thread, but never touches this), so no lock is needed.
+    """
+    scanning:      bool = False
+    scanned_bytes: int  = 0
+    total_bytes:   int  = 0
+    # Basename only, deliberately not the full path — enough to show progress
+    # without broadcasting the operator's directory structure.
+    current_dir:   str  = ""
+
+
 def _virtual_dir(root: Root, file_path: Path) -> str:
     """
     The directory a file appears in, as members see it: `"Films/2024"`.
@@ -87,6 +110,17 @@ def _virtual_dir(root: Root, file_path: Path) -> str:
     return root.name if str(rel) == "." else f"{root.name}/{rel.as_posix()}"
 
 
+def _walk_root(root: Root) -> list[Path]:
+    """
+    Blocking directory walk — always run via an executor, never awaited
+    directly in the asyncio loop. A tree of tens of thousands of files (or
+    one on a slow network share) can take seconds; run inline, that stalls
+    every other thing the daemon is doing — WebRTC sessions, chat, the admin
+    UI — for as long as it takes.
+    """
+    return [p for p in root.path.rglob("*") if p.is_file()]
+
+
 def _scan_file(root: Root, file_path: Path) -> IndexEntry | None:
     """Compute IndexEntry for a file. Blocking — run in executor.
     Uses streaming blake3 so arbitrarily large files (ISOs, VM images, etc.)
@@ -136,8 +170,17 @@ class DirectoryIndexer:
     # How often to re-check which roots are readable and reconcile the index
     # against what is actually on disk. Not a poll for changes — a backstop for
     # the events the OS did not deliver, and the way a re-plugged drive is
-    # noticed.
-    RECONCILE_SECS = 60.0
+    # noticed. Watchdog already covers the common case in real time, so this
+    # does not need to run often to do its job; it backs off further still
+    # (see _reconcile_loop) when nothing has changed for a while, and a
+    # per-group operator setting (roster.py SETTING_RECONCILE_INTERVAL) can
+    # override the starting point.
+    DEFAULT_RECONCILE_SECS = 600.0    # 10 min
+    RECONCILE_BACKOFF_CAP  = 7200.0   # 2 h — never sleeps longer than this
+    # How long to wait after the last event on a given path before acting on
+    # it — several writes to the same file in quick succession (a slow copy
+    # in several passes) collapse into one hash instead of one per write.
+    DEFAULT_DEBOUNCE_SECS = 2.0
 
     def __init__(
         self,
@@ -146,20 +189,43 @@ class DirectoryIndexer:
         sk_node: Ed25519PrivateKey,
         gek: bytes | None,
         on_change: Callable[["DirectoryIndexer"], Awaitable[None]] | None = None,
+        cache: IndexCache | None = None,
+        reconcile_secs: float = DEFAULT_RECONCILE_SECS,
+        debounce_secs: float = DEFAULT_DEBOUNCE_SECS,
     ):
         self.roots    = roots
         self.group_id = group_id
         self.sk_node  = sk_node
         self.gek      = gek
         self.on_change = on_change
+        self.reconcile_secs = reconcile_secs
+        self.debounce_secs = debounce_secs
+        # Current backoff delay — starts at reconcile_secs, doubles on every
+        # tick that finds nothing changed (up to RECONCILE_BACKOFF_CAP), and
+        # resets the moment something real happens (a change, or a peer
+        # connecting — see note_activity()).
+        self._reconcile_delay = reconcile_secs
+        # Path -> (size, mtime, hash) accelerator, so a restart does not have
+        # to re-read a file it already hashed last time (see cache.py). None
+        # in tests that do not care about it — every hash is then a miss.
+        self._cache = cache
 
         self._index    = GroupIndex(group_id=group_id, sk_node=sk_node, gek=gek)
         self._index.roots = roots.describe()
-        self._executor = ThreadPoolExecutor(max_workers=2, thread_name_prefix="indexer")
+        # One worker, deliberately, not a real pool: hashing two files at once
+        # buys nothing here and can cost a lot. It only offloads the blocking
+        # read+hash off the asyncio loop; it was never used for concurrency —
+        # every call site awaits one run_in_executor before starting the next
+        # (see _hash_or_cached below) — and measured on a spinning USB drive,
+        # two interleaved multi-GB reads would seek-thrash against each other
+        # rather than go faster. Left at 1 so the number does not promise a
+        # concurrency this code never provided.
+        self._executor = ThreadPoolExecutor(max_workers=1, thread_name_prefix="indexer")
         self._observer: Observer | None = None
         self._loop: asyncio.AbstractEventLoop | None = None
         self._reconciler: asyncio.Task | None = None
         self._pending_timers: dict[str, asyncio.TimerHandle] = {}
+        self.progress = IndexProgress()
 
     @property
     def index(self) -> GroupIndex:
@@ -204,21 +270,77 @@ class DirectoryIndexer:
 
     async def _scan_root(self, root: Root) -> int:
         log.info("Scanning %s (root %r) ...", root.path, root.name)
-        loop = asyncio.get_event_loop()
         count = 0
+        loop = asyncio.get_event_loop()
         try:
-            files = [p for p in root.path.rglob("*") if p.is_file()]
+            files = await loop.run_in_executor(self._executor, _walk_root, root)
         except OSError as e:
             log.warning("Cannot scan root %r: %s", root.name, e)
             return 0
-        for file_path in files:
-            entry = await loop.run_in_executor(
-                self._executor, _scan_file, root, file_path)
-            if entry:
-                self._index.add_entry(entry)
-                count += 1
+
+        # Sizes up front, off the same listing that already walked the tree —
+        # the progress bar's denominator, not a second pass over the disk.
+        sized: list[tuple[Path, int]] = []
+        for p in files:
+            try:
+                sized.append((p, p.stat().st_size))
+            except OSError:
+                continue
+
+        self.progress.scanning = True
+        self.progress.scanned_bytes = 0
+        self.progress.total_bytes = sum(size for _, size in sized)
+        self.progress.current_dir = ""
+        try:
+            for file_path, size in sized:
+                self.progress.current_dir = file_path.parent.name
+                entry = await self._hash_or_cached(root, file_path)
+                self.progress.scanned_bytes += size
+                if entry:
+                    self._index.add_entry(entry)
+                    count += 1
+        finally:
+            # Must run even if a hash/IO error propagates out of the loop
+            # above — an indexing state that never turns back off is worse
+            # than the scan itself failing.
+            self.progress.scanning = False
+            self.progress.current_dir = ""
         return count
 
+    async def _hash_or_cached(self, root: Root, file_path: Path) -> IndexEntry | None:
+        """
+        Cache-aware replacement for a bare _scan_file() call: skips the
+        content read entirely when this path's (size, mtime) still match
+        what was hashed last time — the difference between a redundant full
+        rehash of a 100+ GB library on every restart and a stat()-only pass.
+        The only place that decides to actually read a file's bytes.
+        """
+        if not _is_indexable(file_path):
+            return None
+        try:
+            st = file_path.stat()
+        except OSError:
+            return None
+
+        if self._cache is not None:
+            cached = await self._cache.lookup(str(file_path), st.st_size, st.st_mtime)
+            if cached is not None:
+                return IndexEntry(
+                    id=cached.hash,
+                    name=file_path.name,
+                    path=_virtual_dir(root, file_path),
+                    size=st.st_size,
+                    type=cached.type,
+                    added_at=cached.added_at,
+                )
+
+        loop = asyncio.get_event_loop()
+        entry = await loop.run_in_executor(self._executor, _scan_file, root, file_path)
+        if entry and self._cache is not None:
+            await self._cache.put(str(file_path), st.st_size, st.st_mtime,
+                                   entry.id, entry.type, entry.added_at)
+        return entry
+
     def _report_collisions(self) -> None:
         """
         Names that are the same file on a case-insensitive filesystem.
@@ -324,20 +446,38 @@ class DirectoryIndexer:
     async def _reconcile_loop(self) -> None:
         while True:
             try:
-                await asyncio.sleep(self.RECONCILE_SECS)
-                await self.reconcile()
+                await asyncio.sleep(self._reconcile_delay)
+                changed = await self.reconcile()
+                if changed:
+                    self._reconcile_delay = self.reconcile_secs
+                else:
+                    self._reconcile_delay = min(
+                        self._reconcile_delay * 2, self.RECONCILE_BACKOFF_CAP)
             except asyncio.CancelledError:
                 raise
             except Exception:
                 log.exception("Reconcile failed — continuing")
 
-    async def reconcile(self) -> None:
+    def note_activity(self) -> None:
+        """
+        Called when something makes a prompt reconcile worth having again —
+        today, a peer completing the handshake for this group
+        (webrtc_server.py). Someone is looking, so the backstop should be at
+        its normal cadence rather than however far backoff had stretched it.
+        """
+        self._reconcile_delay = self.reconcile_secs
+
+    async def reconcile(self) -> bool:
         """
         Re-check availability, and rescan roots that came back.
 
         The only place a root's entries are dropped: when the root is readable
         and the files are genuinely gone. A root that is not readable is left
         untouched, which is the whole point.
+
+        Returns whether anything actually changed — _reconcile_loop uses this
+        to back off when a pass finds nothing to do, rather than running at
+        the same cadence forever regardless of how quiet the root is.
         """
         changed = self.roots.refresh_availability()
         touched = False
@@ -367,6 +507,8 @@ class DirectoryIndexer:
             if self.on_change:
                 await self.on_change(self)
 
+        return touched
+
     async def _sweep_available_roots(self) -> bool:
         """
         Catch what the watcher missed: files gone, and files never announced.
@@ -375,24 +517,18 @@ class DirectoryIndexer:
         absent has nothing to compare against, and comparing anyway is exactly
         the mistake this module exists to avoid.
         """
-        loop = asyncio.get_event_loop()
         changed = False
+        loop = asyncio.get_event_loop()
         for root in self.roots:
             if not root.available:
                 continue
             try:
-                on_disk = {p.resolve() for p in root.path.rglob("*")
-                           if _is_indexable(p)}
+                on_disk, known = await loop.run_in_executor(
+                    self._executor, self._sweep_scan_root, root)
             except OSError as e:
                 log.warning("Cannot reconcile root %r: %s", root.name, e)
                 continue
 
-            known: dict[Path, str] = {}
-            for entry in self._entries_under(root):
-                abs_path = self._entry_path(root, entry)
-                if abs_path:
-                    known[abs_path] = entry.id
-
             for missing in set(known) - on_disk:
                 # Duplicate content is handled without a special case here: the
                 # entry goes, and the add loop below re-indexes the surviving
@@ -404,26 +540,46 @@ class DirectoryIndexer:
                 log.info("Reconcile: %s is gone", missing)
                 changed = True
 
-            for added in on_disk - set(known):
-                entry = await loop.run_in_executor(
-                    self._executor, _scan_file, root, added)
-                if not entry:
-                    continue
-                # The index is keyed by **content hash**, so two identical files
-                # at two paths are one entry and the path comparison above
-                # cannot see the second. Adding it anyway rewrites that entry's
-                # path every cycle, bumps the version, and pushes an index
-                # update to every connected peer once a minute — for ever.
-                # Measured on a live node: `clip.mp4` present at the root and in
-                # uploads/ with the same bytes.
-                if self._index.get_entry(entry.id) is not None:
-                    log.debug("Reconcile: %s duplicates content already indexed "
-                              "as %s — leaving the index alone",
-                              added, entry.id[:8])
-                    continue
-                self._index.add_entry(entry)
-                log.info("Reconcile: %s appeared (missed event)", added)
-                changed = True
+            added_paths = on_disk - set(known)
+            if not added_paths:
+                continue
+
+            added_sized: list[tuple[Path, int]] = []
+            for p in added_paths:
+                try:
+                    added_sized.append((p, p.stat().st_size))
+                except OSError:
+                    added_sized.append((p, 0))
+
+            self.progress.scanning = True
+            self.progress.scanned_bytes = 0
+            self.progress.total_bytes = sum(size for _, size in added_sized)
+            self.progress.current_dir = ""
+            try:
+                for added, size in added_sized:
+                    self.progress.current_dir = added.parent.name
+                    entry = await self._hash_or_cached(root, added)
+                    self.progress.scanned_bytes += size
+                    if not entry:
+                        continue
+                    # The index is keyed by **content hash**, so two identical
+                    # files at two paths are one entry and the path comparison
+                    # above cannot see the second. Adding it anyway rewrites
+                    # that entry's path every cycle, bumps the version, and
+                    # pushes an index update to every connected peer once a
+                    # minute — for ever. Measured on a live node: `clip.mp4`
+                    # present at the root and in uploads/ with the same bytes.
+                    if self._index.get_entry(entry.id) is not None:
+                        log.debug("Reconcile: %s duplicates content already "
+                                  "indexed as %s — leaving the index alone",
+                                  added, entry.id[:8])
+                        continue
+                    self._index.add_entry(entry)
+                    log.info("Reconcile: %s appeared (missed event)", added)
+                    changed = True
+            finally:
+                self.progress.scanning = False
+                self.progress.current_dir = ""
         return changed
 
     def _entries_under(self, root: Root) -> list[IndexEntry]:
@@ -444,6 +600,21 @@ class DirectoryIndexer:
         except OSError:
             return None
 
+    def _sweep_scan_root(self, root: Root) -> tuple[set[Path], dict[Path, str]]:
+        """
+        Blocking: the two disk-touching pieces of one reconcile pass for a
+        root, bundled so both run together in the executor rather than in
+        the asyncio loop — the tree walk, and resolving the real path of
+        every entry already known under this root (one syscall each).
+        """
+        on_disk = {p.resolve() for p in root.path.rglob("*") if _is_indexable(p)}
+        known: dict[Path, str] = {}
+        for entry in self._entries_under(root):
+            abs_path = self._entry_path(root, entry)
+            if abs_path:
+                known[abs_path] = entry.id
+        return on_disk, known
+
     def _restart_observer(self) -> None:
         """Re-schedule watches after roots appeared or disappeared."""
         if self._observer:
@@ -454,8 +625,6 @@ class DirectoryIndexer:
 
     # ── Internal update ───────────────────────────────────────────────────────
 
-    _DEBOUNCE_SECS = 2.0
-
     def _schedule_update(self, file_path: Path, deleted: bool = False) -> None:
         """Called from watchdog thread — schedule debounced async update."""
         if not self._loop:
@@ -472,7 +641,7 @@ class DirectoryIndexer:
             self._pending_timers.pop(key, None)
             asyncio.ensure_future(self._update_entry(file_path, deleted))
 
-        self._pending_timers[key] = self._loop.call_later(self._DEBOUNCE_SECS, fire)
+        self._pending_timers[key] = self._loop.call_later(self.debounce_secs, fire)
 
     def _remove_by_path(self, root: Root, file_path: Path) -> None:
         """Remove any existing entries that point at this file."""
@@ -511,9 +680,7 @@ class DirectoryIndexer:
         self._remove_by_path(root, file_path)
 
         if not deleted:
-            loop = asyncio.get_event_loop()
-            entry = await loop.run_in_executor(
-                self._executor, _scan_file, root, file_path)
+            entry = await self._hash_or_cached(root, file_path)
             if entry:
                 self._index.add_entry(entry)
                 log.debug("Indexed: %s (%s, %d bytes)",