fix: prevent convo_miner from re-processing 0-chunk files on every run (#654) (#732)

* fix: register 0-chunk files to prevent re-processing on every mine (#654)

mine_convos() has three early-exit paths (OSError, content too short,
zero chunks) that skip writing anything to ChromaDB. Since
file_already_mined() checks for the presence of a document with a
matching source_file, these files are re-read and re-processed on
every subsequent run.

Add _register_file() that upserts a lightweight sentinel document
(room="_registry", ingest_mode="registry") so file_already_mined()
returns True on future runs.

Note: Bug 2 from the issue (drawers_added counter always 0) was
already resolved upstream via the switch from collection.add() to
collection.upsert().

* fix: resolve macOS path symlink in test + remove unused variable

mempalace/convo_miner.py

@@ -32,6 +32,30 @@ CHUNK_SIZE = 800  # chars per drawer — align with miner.py
 MAX_FILE_SIZE = 10 * 1024 * 1024  # 10 MB — skip files larger than this
 
 
+def _register_file(collection, source_file: str, wing: str, agent: str):
+    """Write a sentinel so file_already_mined() returns True for 0-chunk files.
+
+    Without this, files that normalize to nothing or produce zero chunks are
+    re-read and re-processed on every mine run because nothing was written to
+    ChromaDB on the first pass.
+    """
+    sentinel_id = f"_reg_{hashlib.sha256(source_file.encode()).hexdigest()[:24]}"
+    collection.upsert(
+        documents=[f"[registry] {source_file}"],
+        ids=[sentinel_id],
+        metadatas=[
+            {
+                "wing": wing,
+                "room": "_registry",
+                "source_file": source_file,
+                "added_by": agent,
+                "filed_at": datetime.now().isoformat(),
+                "ingest_mode": "registry",
+            }
+        ],
+    )
+
+
 # =============================================================================
 # CHUNKING — exchange pairs for conversations
 # =============================================================================
@@ -305,9 +329,13 @@ def mine_convos(
         try:
             content = normalize(str(filepath))
         except (OSError, ValueError):
+            if not dry_run:
+                _register_file(collection, source_file, wing, agent)
             continue
 
         if not content or len(content.strip()) < MIN_CHUNK_SIZE:
+            if not dry_run:
+                _register_file(collection, source_file, wing, agent)
             continue
 
         # Chunk — either exchange pairs or general extraction
@@ -320,6 +348,8 @@ def mine_convos(
             chunks = chunk_exchanges(content)
 
         if not chunks:
+            if not dry_run:
+                _register_file(collection, source_file, wing, agent)
             continue
 
         # Detect room from content (general mode uses memory_type instead)