From 7d80eb4f83c3e4fbd206835363b970e9fe0b776a Mon Sep 17 00:00:00 2001
From: Chris McDonough <chrism@plope.com>
Date: Mon, 1 Jun 2026 07:29:51 -0400
Subject: [PATCH] Fix discover() crash when file is deleted during stat()

A file deleted between os.walk() and path.stat() raises
FileNotFoundError, which propagated uncaught and failed the entire
discover() sweep. With enough failures this trips the circuit
breaker, silencing the poller.

Catch FileNotFoundError around the stat() call and skip the file.
The next sweep (or watchfiles) will emit the DELETE event.
---
 .../haiku/rag/ingester/sources/fs.py          |  7 ++++++-
 tests/ingester/test_fs_source.py              | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/haiku_rag_slim/haiku/rag/ingester/sources/fs.py b/haiku_rag_slim/haiku/rag/ingester/sources/fs.py
index 8b944e04..8de87469 100644
--- a/haiku_rag_slim/haiku/rag/ingester/sources/fs.py
+++ b/haiku_rag_slim/haiku/rag/ingester/sources/fs.py
@@ -139,7 +139,12 @@ class FSSource:
             if not self.filter.include_file(str(path)):
                 continue
             uri = path.as_uri()
-            revision = str(path.stat().st_mtime_ns)
+            try:
+                revision = str(path.stat().st_mtime_ns)
+            except FileNotFoundError:
+                # File was deleted between the os.walk() and stat() call.
+                # Skip it — the next sweep (or watchfiles) will emit DELETE.
+                continue
             seen.add(uri)
             previous = snapshot.get(uri)
             kind = (
diff --git a/tests/ingester/test_fs_source.py b/tests/ingester/test_fs_source.py
index df32304f..c827bf0e 100644
--- a/tests/ingester/test_fs_source.py
+++ b/tests/ingester/test_fs_source.py
@@ -131,6 +131,25 @@ async def test_fs_source_discover_respects_extension_filter(fs_root: Path):
     assert (fs_root / "b.txt").as_uri() not in uris
 
 
+@pytest.mark.asyncio
+async def test_fs_source_discover_skips_file_deleted_during_stat(fs_root: Path):
+    """A file deleted between os.walk() and stat() should be silently
+    skipped instead of crashing the entire discover() sweep."""
+    src = FSSource(root=fs_root, supported_extensions=[".md", ".txt"])
+    events = []
+    async for event in src.discover(since=None):
+        events.append(event)
+        # Delete a file mid-iteration so the next stat() hits a missing file.
+        victim = fs_root / "b.txt"
+        if victim.exists():
+            victim.unlink()
+    uris = {e.uri for e in events}
+    # a.md and sub/c.md should still appear; b.txt may or may not depending
+    # on iteration order, but the key assertion is no exception was raised.
+    assert (fs_root / "a.md").as_uri() in uris
+    assert (fs_root / "sub" / "c.md").as_uri() in uris
+
+
 @pytest.mark.asyncio
 async def test_fs_source_discover_respects_ignore_patterns(fs_root: Path):
     src = FSSource(