DOT-481 Port upstream fix: miner room stats double-detection (upstream #165)

This change is part of the following stack:

• fix: return room from process_file to fix stats double-detection #45 ◀

_{Change managed by git-spice.}

Greptile Summary

This PR changes process_file to return (drawer_count, room) instead of just drawer_count, so mine() can reuse the room determined inside process_file for stats rather than calling detect_room a second time. All call sites and tests are updated to unpack the tuple.

• When dry_run=True, files skipped early (too small, OSError) return (0, ""). The guard if drawers == 0 and not dry_run: is False in dry-run mode, so execution falls to the else branch and room_counts[""] += 1. The dry-run "By room:" summary would then display an entry with a blank room name for each such file.

Confidence Score: 5/5

Safe to merge; the core fix is correct and all tests pass. The one finding is a cosmetic dry-run edge case.

The fix correctly eliminates redundant room detection and all callers are updated. The only remaining finding is a P2: dry-run summaries could show a blank room name for files too small to process, which does not affect real mine runs or data integrity.

src/mempalace/miner.py — the else-branch in mine() around line 627

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant mine
    participant process_file
    participant detect_room
    participant ChromaDB

    Note over mine,ChromaDB: After PR — single room detection
    mine->>process_file: filepath, rooms, dry_run, ...
    process_file->>detect_room: filepath, content, rooms
    detect_room-->>process_file: room (str)
    process_file->>ChromaDB: delete(source_file)
    process_file->>ChromaDB: add drawers
    ChromaDB-->>process_file: ok
    process_file-->>mine: (drawer_count, room)
    mine->>mine: room_counts[room] += 1

    Note over mine,ChromaDB: Before PR — room detected twice
    mine->>process_file: filepath, rooms, dry_run, ...
    process_file->>detect_room: filepath, content, rooms
    detect_room-->>process_file: room (internal, unused by caller)
    process_file-->>mine: drawer_count (int only)
    mine->>detect_room: filepath, content, rooms
    detect_room-->>mine: room (redundant call)
    mine->>mine: room_counts[room] += 1

_{Reviews (1): Last reviewed commit: "fix: return room from process_file to fi..." | Re-trigger Greptile}