diff --git a/mempalace/convo_miner.py b/mempalace/convo_miner.py
index 7879f96..3bb4a89 100644
--- a/mempalace/convo_miner.py
+++ b/mempalace/convo_miner.py
@@ -334,7 +334,7 @@ def mine_convos(
                 room_counts[chunk_room] += 1
             drawer_id = f"drawer_{wing}_{chunk_room}_{hashlib.sha256((source_file + str(chunk['chunk_index'])).encode()).hexdigest()[:24]}"
             try:
-                collection.add(
+                collection.upsert(
                     documents=[chunk["content"]],
                     ids=[drawer_id],
                     metadatas=[
diff --git a/mempalace/dedup.py b/mempalace/dedup.py
new file mode 100644
index 0000000..c2f9f6b
--- /dev/null
+++ b/mempalace/dedup.py
@@ -0,0 +1,239 @@
+"""
+dedup.py — Detect and remove near-duplicate drawers
+====================================================
+
+When the same files are mined multiple times, near-identical drawers
+accumulate. This module finds drawers from the same source_file that
+are too similar (cosine distance < threshold), keeps the longest/richest
+version, and deletes the rest.
+
+No API calls — uses ChromaDB's built-in embedding similarity.
+
+Usage (standalone):
+    python -m mempalace.dedup                          # dedup all
+    python -m mempalace.dedup --dry-run                # preview only
+    python -m mempalace.dedup --threshold 0.10         # stricter (near-identical only)
+    python -m mempalace.dedup --threshold 0.35         # looser (catches paraphrased content)
+    python -m mempalace.dedup --wing my_project        # scope to one wing
+    python -m mempalace.dedup --stats                  # stats only
+    python -m mempalace.dedup --source "my_project"    # filter by source
+
+Usage (from CLI):
+    mempalace dedup [--dry-run] [--threshold 0.15] [--stats]
+"""
+
+import argparse
+import os
+import time
+from collections import defaultdict
+
+import chromadb
+
+
+COLLECTION_NAME = "mempalace_drawers"
+# Cosine DISTANCE threshold (not similarity). Lower = stricter.
+# 0.15 = ~85% cosine similarity — catches near-identical chunks.
+# For looser dedup of paraphrased content, try 0.3–0.4.
+DEFAULT_THRESHOLD = 0.15
+MIN_DRAWERS_TO_CHECK = 5
+
+
+def _get_palace_path():
+    """Resolve palace path from config."""
+    try:
+        from .config import MempalaceConfig
+
+        return MempalaceConfig().palace_path
+    except Exception:
+        return os.path.join(os.path.expanduser("~"), ".mempalace", "palace")
+
+
+def get_source_groups(col, min_count=MIN_DRAWERS_TO_CHECK, source_pattern=None, wing=None):
+    """Group drawers by source_file, return groups with min_count+ entries.
+
+    If wing is specified, only considers drawers in that wing. This catches
+    cross-wing duplicates when the same source was mined into multiple wings.
+    """
+    total = col.count()
+    groups = defaultdict(list)
+
+    offset = 0
+    batch_size = 1000
+    while offset < total:
+        kwargs = {"limit": batch_size, "offset": offset, "include": ["metadatas"]}
+        if wing:
+            kwargs["where"] = {"wing": wing}
+        batch = col.get(**kwargs)
+        if not batch["ids"]:
+            break
+        for did, meta in zip(batch["ids"], batch["metadatas"]):
+            src = meta.get("source_file", "unknown")
+            if source_pattern and source_pattern.lower() not in src.lower():
+                continue
+            groups[src].append(did)
+        offset += len(batch["ids"])
+
+    return {src: ids for src, ids in groups.items() if len(ids) >= min_count}
+
+
+def dedup_source_group(col, drawer_ids, threshold=DEFAULT_THRESHOLD, dry_run=True):
+    """Dedup drawers within one source_file group.
+
+    Greedy: sort by doc length (longest first), keep if not too similar
+    to any already-kept drawer. Returns (kept_ids, deleted_ids).
+    """
+    data = col.get(ids=drawer_ids, include=["documents", "metadatas"])
+    items = list(zip(data["ids"], data["documents"], data["metadatas"]))
+    items.sort(key=lambda x: len(x[1] or ""), reverse=True)
+
+    kept = []
+    to_delete = []
+
+    for did, doc, meta in items:
+        if not doc or len(doc) < 20:
+            to_delete.append(did)
+            continue
+
+        if not kept:
+            kept.append((did, doc))
+            continue
+
+        try:
+            results = col.query(
+                query_texts=[doc],
+                n_results=min(len(kept), 5),
+                include=["distances"],
+            )
+            dists = results["distances"][0] if results["distances"] else []
+            kept_ids_set = {k[0] for k in kept}
+
+            is_dup = False
+            for rid, dist in zip(results["ids"][0], dists):
+                if rid in kept_ids_set and dist < threshold:
+                    is_dup = True
+                    break
+
+            if is_dup:
+                to_delete.append(did)
+            else:
+                kept.append((did, doc))
+        except Exception:
+            kept.append((did, doc))
+
+    if to_delete and not dry_run:
+        for i in range(0, len(to_delete), 500):
+            col.delete(ids=to_delete[i : i + 500])
+
+    return [k[0] for k in kept], to_delete
+
+
+def show_stats(palace_path=None):
+    """Show duplication statistics without making changes."""
+    palace_path = palace_path or _get_palace_path()
+    client = chromadb.PersistentClient(path=palace_path)
+    col = client.get_collection(COLLECTION_NAME)
+
+    groups = get_source_groups(col)
+
+    total_drawers = sum(len(ids) for ids in groups.values())
+    print(f"\n  Sources with {MIN_DRAWERS_TO_CHECK}+ drawers: {len(groups)}")
+    print(f"  Total drawers in those sources: {total_drawers:,}")
+
+    print("\n  Top 15 by drawer count:")
+    sorted_groups = sorted(groups.items(), key=lambda x: len(x[1]), reverse=True)
+    for src, ids in sorted_groups[:15]:
+        print(f"    {len(ids):4d}  {src[:65]}")
+
+    estimated_dups = sum(int(len(ids) * 0.4) for ids in groups.values() if len(ids) > 20)
+    print(f"\n  Estimated duplicates (groups > 20): ~{estimated_dups:,}")
+
+
+def dedup_palace(
+    palace_path=None,
+    threshold=DEFAULT_THRESHOLD,
+    dry_run=True,
+    source_pattern=None,
+    min_count=MIN_DRAWERS_TO_CHECK,
+    wing=None,
+):
+    """Main entry point: deduplicate near-identical drawers across the palace."""
+    palace_path = palace_path or _get_palace_path()
+
+    print(f"\n{'=' * 55}")
+    print("  MemPalace Deduplicator")
+    print(f"{'=' * 55}")
+
+    client = chromadb.PersistentClient(path=palace_path)
+    col = client.get_collection(COLLECTION_NAME)
+
+    print(f"  Palace: {palace_path}")
+    print(f"  Drawers: {col.count():,}")
+    print(f"  Threshold: {threshold}")
+    print(f"  Mode: {'DRY RUN' if dry_run else 'LIVE'}")
+    print(f"{'─' * 55}")
+
+    if wing:
+        print(f"  Wing: {wing}")
+    groups = get_source_groups(col, min_count, source_pattern, wing=wing)
+    print(f"\n  Sources to check: {len(groups)}")
+
+    t0 = time.time()
+    total_kept = 0
+    total_deleted = 0
+
+    sorted_groups = sorted(groups.items(), key=lambda x: len(x[1]), reverse=True)
+
+    for i, (src, drawer_ids) in enumerate(sorted_groups):
+        kept, deleted = dedup_source_group(col, drawer_ids, threshold, dry_run)
+        total_kept += len(kept)
+        total_deleted += len(deleted)
+
+        if deleted:
+            print(
+                f"  [{i + 1:3d}/{len(groups)}] "
+                f"{src[:50]:50s} {len(drawer_ids):4d} → {len(kept):4d}  "
+                f"(-{len(deleted)})"
+            )
+
+    elapsed = time.time() - t0
+
+    print(f"\n{'─' * 55}")
+    print(f"  Done in {elapsed:.1f}s")
+    print(
+        f"  Drawers: {total_kept + total_deleted:,} → {total_kept:,}  (-{total_deleted:,} removed)"
+    )
+    print(f"  Palace after: {col.count():,} drawers")
+
+    if dry_run:
+        print("\n  [DRY RUN] No changes written. Re-run without --dry-run to apply.")
+
+    print(f"{'=' * 55}\n")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Deduplicate near-identical drawers")
+    parser.add_argument("--palace", default=None, help="Palace directory path")
+    parser.add_argument(
+        "--threshold",
+        type=float,
+        default=DEFAULT_THRESHOLD,
+        help=f"Cosine distance threshold (default: {DEFAULT_THRESHOLD})",
+    )
+    parser.add_argument("--dry-run", action="store_true", help="Preview without deleting")
+    parser.add_argument("--stats", action="store_true", help="Show stats only")
+    parser.add_argument("--wing", default=None, help="Scope dedup to a single wing")
+    parser.add_argument("--source", default=None, help="Filter by source file pattern")
+    args = parser.parse_args()
+
+    path = os.path.expanduser(args.palace) if args.palace else None
+
+    if args.stats:
+        show_stats(palace_path=path)
+    else:
+        dedup_palace(
+            palace_path=path,
+            threshold=args.threshold,
+            dry_run=args.dry_run,
+            source_pattern=args.source,
+            wing=args.wing,
+        )
diff --git a/mempalace/hooks_cli.py b/mempalace/hooks_cli.py
index 3f3fc09..b6d2290 100644
--- a/mempalace/hooks_cli.py
+++ b/mempalace/hooks_cli.py
@@ -63,6 +63,14 @@ def _count_human_messages(transcript_path: str) -> int:
                             if "<command-message>" in text:
                                 continue
                         count += 1
+                    # Also handle Codex CLI transcript format
+                    # {"type": "event_msg", "payload": {"type": "user_message", "message": "..."}}
+                    elif entry.get("type") == "event_msg":
+                        payload = entry.get("payload", {})
+                        if isinstance(payload, dict) and payload.get("type") == "user_message":
+                            msg_text = payload.get("message", "")
+                            if isinstance(msg_text, str) and "<command-message>" not in msg_text:
+                                count += 1
                 except (json.JSONDecodeError, AttributeError):
                     pass
     except OSError:
diff --git a/mempalace/miner.py b/mempalace/miner.py
index b52e6f7..f342a2d 100644
--- a/mempalace/miner.py
+++ b/mempalace/miner.py
@@ -436,6 +436,16 @@ def process_file(
         print(f"    [DRY RUN] {filepath.name} → room:{room} ({len(chunks)} drawers)")
         return len(chunks), room
 
+    # Purge stale drawers for this file before re-inserting the fresh chunks.
+    # Converts modified-file re-mines from upsert-over-existing-IDs (which hits
+    # hnswlib's thread-unsafe updatePoint path and can segfault on macOS ARM
+    # with chromadb 0.6.3) into a clean delete+insert, bypassing the update
+    # path entirely.
+    try:
+        collection.delete(where={"source_file": source_file})
+    except Exception:
+        pass
+
     drawers_added = 0
     for chunk in chunks:
         added = add_drawer(
diff --git a/mempalace/repair.py b/mempalace/repair.py
new file mode 100644
index 0000000..d51be60
--- /dev/null
+++ b/mempalace/repair.py
@@ -0,0 +1,299 @@
+"""
+repair.py — Scan, prune corrupt entries, and rebuild HNSW index
+================================================================
+
+When ChromaDB's HNSW index accumulates duplicate entries (from repeated
+add() calls with the same ID), link_lists.bin can grow unbounded —
+terabytes on large palaces — eventually causing segfaults.
+
+This module provides three operations:
+
+  scan    — find every corrupt/unfetchable ID in the palace
+  prune   — delete only the corrupt IDs (surgical)
+  rebuild — extract all drawers, delete the collection, recreate with
+            correct HNSW settings, and upsert everything back
+
+The rebuild backs up ONLY chroma.sqlite3 (the source of truth), not the
+full palace directory — so it works even when link_lists.bin is bloated.
+
+Usage (standalone):
+    python -m mempalace.repair scan [--wing X]
+    python -m mempalace.repair prune --confirm
+    python -m mempalace.repair rebuild
+
+Usage (from CLI):
+    mempalace repair
+    mempalace repair-scan [--wing X]
+    mempalace repair-prune --confirm
+"""
+
+import argparse
+import os
+import shutil
+import time
+
+import chromadb
+
+
+COLLECTION_NAME = "mempalace_drawers"
+
+
+def _get_palace_path():
+    """Resolve palace path from config."""
+    try:
+        from .config import MempalaceConfig
+
+        return MempalaceConfig().palace_path
+    except Exception:
+        default = os.path.join(os.path.expanduser("~"), ".mempalace", "palace")
+        return default
+
+
+def _paginate_ids(col, where=None):
+    """Pull all IDs in a collection using pagination."""
+    ids = []
+    page = 1000
+    offset = 0
+    while True:
+        try:
+            r = col.get(where=where, include=[], limit=page, offset=offset)
+        except Exception:
+            try:
+                r = col.get(where=where, include=[], limit=page)
+                new_ids = [i for i in r["ids"] if i not in set(ids)]
+                if not new_ids:
+                    break
+                ids.extend(new_ids)
+                offset += len(new_ids)
+                continue
+            except Exception:
+                break
+        n = len(r["ids"]) if r["ids"] else 0
+        if n == 0:
+            break
+        ids.extend(r["ids"])
+        offset += n
+        if n < page:
+            break
+    return ids
+
+
+def scan_palace(palace_path=None, only_wing=None):
+    """Scan the palace for corrupt/unfetchable IDs.
+
+    Probes in batches of 100, falls back to per-ID on failure.
+    Writes corrupt_ids.txt to the palace directory for the prune step.
+
+    Returns (good_set, bad_set).
+    """
+    palace_path = palace_path or _get_palace_path()
+    print(f"\n  Palace: {palace_path}")
+    print("  Loading...")
+
+    client = chromadb.PersistentClient(path=palace_path)
+    col = client.get_collection(COLLECTION_NAME)
+
+    where = {"wing": only_wing} if only_wing else None
+    total = col.count()
+    print(f"  Collection: {COLLECTION_NAME}, total: {total:,}")
+    if only_wing:
+        print(f"  Scanning wing: {only_wing}")
+
+    print("\n  Step 1: listing all IDs...")
+    t0 = time.time()
+    all_ids = _paginate_ids(col, where=where)
+    print(f"  Found {len(all_ids):,} IDs in {time.time() - t0:.1f}s\n")
+
+    if not all_ids:
+        print("  Nothing to scan.")
+        return set(), set()
+
+    print("  Step 2: probing each ID (batches of 100)...")
+    t0 = time.time()
+    good_set = set()
+    bad_set = set()
+    batch = 100
+
+    for i in range(0, len(all_ids), batch):
+        chunk = all_ids[i : i + batch]
+        try:
+            r = col.get(ids=chunk, include=["documents"])
+            for got in r["ids"]:
+                good_set.add(got)
+            for mid in chunk:
+                if mid not in good_set:
+                    bad_set.add(mid)
+        except Exception:
+            for sid in chunk:
+                try:
+                    r = col.get(ids=[sid], include=["documents"])
+                    if r["ids"]:
+                        good_set.add(sid)
+                    else:
+                        bad_set.add(sid)
+                except Exception:
+                    bad_set.add(sid)
+
+        if (i // batch) % 50 == 0:
+            elapsed = time.time() - t0
+            rate = (i + batch) / max(elapsed, 0.01)
+            eta = (len(all_ids) - i - batch) / max(rate, 0.01)
+            print(
+                f"    {i + batch:>6}/{len(all_ids):>6}  "
+                f"good={len(good_set):>6}  bad={len(bad_set):>6}  "
+                f"eta={eta:.0f}s"
+            )
+
+    print(f"\n  Scan complete in {time.time() - t0:.1f}s")
+    print(f"  GOOD: {len(good_set):,}")
+    print(f"  BAD:  {len(bad_set):,}  ({len(bad_set) / max(len(all_ids), 1) * 100:.1f}%)")
+
+    bad_file = os.path.join(palace_path, "corrupt_ids.txt")
+    with open(bad_file, "w") as f:
+        for bid in sorted(bad_set):
+            f.write(bid + "\n")
+    print(f"\n  Bad IDs written to: {bad_file}")
+    return good_set, bad_set
+
+
+def prune_corrupt(palace_path=None, confirm=False):
+    """Delete corrupt IDs listed in corrupt_ids.txt."""
+    palace_path = palace_path or _get_palace_path()
+    bad_file = os.path.join(palace_path, "corrupt_ids.txt")
+
+    if not os.path.exists(bad_file):
+        print("  No corrupt_ids.txt found — run scan first.")
+        return
+
+    with open(bad_file) as f:
+        bad_ids = [line.strip() for line in f if line.strip()]
+    print(f"  {len(bad_ids):,} corrupt IDs queued for deletion")
+
+    if not confirm:
+        print("\n  DRY RUN — no deletions performed.")
+        print("  Re-run with --confirm to actually delete.")
+        return
+
+    client = chromadb.PersistentClient(path=palace_path)
+    col = client.get_collection(COLLECTION_NAME)
+    before = col.count()
+    print(f"  Collection size before: {before:,}")
+
+    batch = 100
+    deleted = 0
+    failed = 0
+    for i in range(0, len(bad_ids), batch):
+        chunk = bad_ids[i : i + batch]
+        try:
+            col.delete(ids=chunk)
+            deleted += len(chunk)
+        except Exception:
+            for sid in chunk:
+                try:
+                    col.delete(ids=[sid])
+                    deleted += 1
+                except Exception:
+                    failed += 1
+        if (i // batch) % 20 == 0:
+            print(f"    deleted {deleted}/{len(bad_ids)}  (failed: {failed})")
+
+    after = col.count()
+    print(f"\n  Deleted: {deleted:,}")
+    print(f"  Failed:  {failed:,}")
+    print(f"  Collection size: {before:,} → {after:,}")
+
+
+def rebuild_index(palace_path=None):
+    """Rebuild the HNSW index from scratch.
+
+    1. Extract all drawers via ChromaDB get()
+    2. Back up ONLY chroma.sqlite3 (not the bloated HNSW files)
+    3. Delete and recreate the collection with hnsw:space=cosine
+    4. Upsert all drawers back
+    """
+    palace_path = palace_path or _get_palace_path()
+
+    if not os.path.isdir(palace_path):
+        print(f"\n  No palace found at {palace_path}")
+        return
+
+    print(f"\n{'=' * 55}")
+    print("  MemPalace Repair — Index Rebuild")
+    print(f"{'=' * 55}\n")
+    print(f"  Palace: {palace_path}")
+
+    client = chromadb.PersistentClient(path=palace_path)
+    try:
+        col = client.get_collection(COLLECTION_NAME)
+        total = col.count()
+    except Exception as e:
+        print(f"  Error reading palace: {e}")
+        print("  Palace may need to be re-mined from source files.")
+        return
+
+    print(f"  Drawers found: {total}")
+
+    if total == 0:
+        print("  Nothing to repair.")
+        return
+
+    # Extract all drawers in batches
+    print("\n  Extracting drawers...")
+    batch_size = 5000
+    all_ids = []
+    all_docs = []
+    all_metas = []
+    offset = 0
+    while offset < total:
+        batch = col.get(limit=batch_size, offset=offset, include=["documents", "metadatas"])
+        if not batch["ids"]:
+            break
+        all_ids.extend(batch["ids"])
+        all_docs.extend(batch["documents"])
+        all_metas.extend(batch["metadatas"])
+        offset += len(batch["ids"])
+    print(f"  Extracted {len(all_ids)} drawers")
+
+    # Back up ONLY the SQLite database, not the bloated HNSW files
+    sqlite_path = os.path.join(palace_path, "chroma.sqlite3")
+    if os.path.exists(sqlite_path):
+        backup_path = sqlite_path + ".backup"
+        print(f"  Backing up chroma.sqlite3 ({os.path.getsize(sqlite_path) / 1e6:.0f} MB)...")
+        shutil.copy2(sqlite_path, backup_path)
+        print(f"  Backup: {backup_path}")
+
+    # Rebuild with correct HNSW settings
+    print("  Rebuilding collection with hnsw:space=cosine...")
+    client.delete_collection(COLLECTION_NAME)
+    new_col = client.create_collection(COLLECTION_NAME, metadata={"hnsw:space": "cosine"})
+
+    filed = 0
+    for i in range(0, len(all_ids), batch_size):
+        batch_ids = all_ids[i : i + batch_size]
+        batch_docs = all_docs[i : i + batch_size]
+        batch_metas = all_metas[i : i + batch_size]
+        new_col.upsert(documents=batch_docs, ids=batch_ids, metadatas=batch_metas)
+        filed += len(batch_ids)
+        print(f"  Re-filed {filed}/{len(all_ids)} drawers...")
+
+    print(f"\n  Repair complete. {filed} drawers rebuilt.")
+    print("  HNSW index is now clean with cosine distance metric.")
+    print(f"\n{'=' * 55}\n")
+
+
+if __name__ == "__main__":
+    p = argparse.ArgumentParser(description="MemPalace repair tools")
+    p.add_argument("command", choices=["scan", "prune", "rebuild"])
+    p.add_argument("--palace", default=None, help="Palace directory path")
+    p.add_argument("--wing", default=None, help="Scan only this wing")
+    p.add_argument("--confirm", action="store_true", help="Actually delete corrupt IDs")
+    args = p.parse_args()
+
+    path = os.path.expanduser(args.palace) if args.palace else None
+
+    if args.command == "scan":
+        scan_palace(palace_path=path, only_wing=args.wing)
+    elif args.command == "prune":
+        prune_corrupt(palace_path=path, confirm=args.confirm)
+    elif args.command == "rebuild":
+        rebuild_index(palace_path=path)
diff --git a/tests/test_dedup.py b/tests/test_dedup.py
new file mode 100644
index 0000000..2ddffb3
--- /dev/null
+++ b/tests/test_dedup.py
@@ -0,0 +1,272 @@
+"""Tests for mempalace.dedup — near-duplicate drawer detection and removal."""
+
+from unittest.mock import MagicMock, patch
+
+
+from mempalace import dedup
+
+
+# ── get_source_groups ─────────────────────────────────────────────────
+
+
+def test_get_source_groups_basic():
+    col = MagicMock()
+    col.count.return_value = 5
+    col.get.side_effect = [
+        {
+            "ids": ["d1", "d2", "d3", "d4", "d5"],
+            "metadatas": [
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+            ],
+        },
+        {"ids": []},
+    ]
+    groups = dedup.get_source_groups(col, min_count=5)
+    assert "a.txt" in groups
+    assert len(groups["a.txt"]) == 5
+
+
+def test_get_source_groups_below_min():
+    col = MagicMock()
+    col.count.return_value = 2
+    col.get.side_effect = [
+        {
+            "ids": ["d1", "d2"],
+            "metadatas": [
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+            ],
+        },
+        {"ids": []},
+    ]
+    groups = dedup.get_source_groups(col, min_count=5)
+    assert len(groups) == 0
+
+
+def test_get_source_groups_source_filter():
+    col = MagicMock()
+    col.count.return_value = 6
+    col.get.side_effect = [
+        {
+            "ids": ["d1", "d2", "d3", "d4", "d5", "d6"],
+            "metadatas": [
+                {"source_file": "project_a.txt"},
+                {"source_file": "project_a.txt"},
+                {"source_file": "project_a.txt"},
+                {"source_file": "project_a.txt"},
+                {"source_file": "project_a.txt"},
+                {"source_file": "other.txt"},
+            ],
+        },
+        {"ids": []},
+    ]
+    groups = dedup.get_source_groups(col, min_count=5, source_pattern="project_a")
+    assert "project_a.txt" in groups
+    assert "other.txt" not in groups
+
+
+def test_get_source_groups_wing_filter():
+    col = MagicMock()
+    col.count.return_value = 5
+    col.get.side_effect = [
+        {
+            "ids": ["d1", "d2", "d3", "d4", "d5"],
+            "metadatas": [
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+            ],
+        },
+        {"ids": []},
+    ]
+    dedup.get_source_groups(col, min_count=5, wing="my_wing")
+    # Verify where filter was passed
+    first_call = col.get.call_args_list[0]
+    assert first_call.kwargs.get("where") == {"wing": "my_wing"}
+
+
+def test_get_source_groups_missing_source_file():
+    col = MagicMock()
+    col.count.return_value = 5
+    col.get.side_effect = [
+        {
+            "ids": ["d1", "d2", "d3", "d4", "d5"],
+            "metadatas": [{}, {}, {}, {}, {}],
+        },
+        {"ids": []},
+    ]
+    groups = dedup.get_source_groups(col, min_count=5)
+    assert "unknown" in groups
+
+
+# ── dedup_source_group ────────────────────────────────────────────────
+
+
+def test_dedup_source_group_all_unique():
+    col = MagicMock()
+    col.get.return_value = {
+        "ids": ["d1", "d2"],
+        "documents": ["long document one content here", "different document two here"],
+        "metadatas": [{"wing": "a"}, {"wing": "a"}],
+    }
+    col.query.return_value = {
+        "ids": [["d1"]],
+        "distances": [[0.8]],  # far apart = unique
+    }
+    kept, deleted = dedup.dedup_source_group(col, ["d1", "d2"], threshold=0.15, dry_run=True)
+    assert len(kept) == 2
+    assert len(deleted) == 0
+
+
+def test_dedup_source_group_with_duplicate():
+    col = MagicMock()
+    col.get.return_value = {
+        "ids": ["d1", "d2"],
+        "documents": [
+            "long document content that is fairly long",
+            "long document content that is fairly long",
+        ],
+        "metadatas": [{"wing": "a"}, {"wing": "a"}],
+    }
+    col.query.return_value = {
+        "ids": [["d1"]],
+        "distances": [[0.05]],  # very close = duplicate
+    }
+    kept, deleted = dedup.dedup_source_group(col, ["d1", "d2"], threshold=0.15, dry_run=True)
+    assert len(kept) == 1
+    assert len(deleted) == 1
+
+
+def test_dedup_source_group_short_docs_deleted():
+    col = MagicMock()
+    col.get.return_value = {
+        "ids": ["d1", "d2"],
+        "documents": ["long enough document to keep in the palace", "tiny"],
+        "metadatas": [{"wing": "a"}, {"wing": "a"}],
+    }
+    kept, deleted = dedup.dedup_source_group(col, ["d1", "d2"], threshold=0.15, dry_run=True)
+    assert "d2" in deleted  # too short
+
+
+def test_dedup_source_group_empty_doc_deleted():
+    col = MagicMock()
+    col.get.return_value = {
+        "ids": ["d1", "d2"],
+        "documents": ["real document content here that is long enough", None],
+        "metadatas": [{"wing": "a"}, {"wing": "a"}],
+    }
+    kept, deleted = dedup.dedup_source_group(col, ["d1", "d2"], threshold=0.15, dry_run=True)
+    assert "d2" in deleted
+
+
+def test_dedup_source_group_live_deletes():
+    col = MagicMock()
+    col.get.return_value = {
+        "ids": ["d1", "d2"],
+        "documents": ["long document content here enough", "long document content here enough"],
+        "metadatas": [{"wing": "a"}, {"wing": "a"}],
+    }
+    col.query.return_value = {
+        "ids": [["d1"]],
+        "distances": [[0.05]],
+    }
+    kept, deleted = dedup.dedup_source_group(col, ["d1", "d2"], threshold=0.15, dry_run=False)
+    col.delete.assert_called_once()
+
+
+def test_dedup_source_group_query_failure_keeps():
+    col = MagicMock()
+    col.get.return_value = {
+        "ids": ["d1", "d2"],
+        "documents": [
+            "long document one content here enough",
+            "long document two content here enough",
+        ],
+        "metadatas": [{"wing": "a"}, {"wing": "a"}],
+    }
+    col.query.side_effect = Exception("query failed")
+    kept, deleted = dedup.dedup_source_group(col, ["d1", "d2"], threshold=0.15, dry_run=True)
+    assert len(kept) == 2  # both kept on error
+
+
+# ── show_stats ────────────────────────────────────────────────────────
+
+
+@patch("mempalace.dedup.chromadb")
+def test_show_stats(mock_chromadb, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 5
+    mock_col.get.side_effect = [
+        {
+            "ids": ["d1", "d2", "d3", "d4", "d5"],
+            "metadatas": [
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+                {"source_file": "a.txt"},
+            ],
+        },
+        {"ids": []},
+    ]
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    dedup.show_stats(palace_path=str(tmp_path))  # should not raise
+
+
+# ── dedup_palace ──────────────────────────────────────────────────────
+
+
+@patch("mempalace.dedup.dedup_source_group")
+@patch("mempalace.dedup.get_source_groups")
+@patch("mempalace.dedup.chromadb")
+def test_dedup_palace_dry_run(mock_chromadb, mock_groups, mock_dedup_group, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 10
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    mock_groups.return_value = {"a.txt": ["d1", "d2", "d3", "d4", "d5"]}
+    mock_dedup_group.return_value = (["d1", "d2", "d3"], ["d4", "d5"])
+
+    dedup.dedup_palace(palace_path=str(tmp_path), dry_run=True)
+    mock_dedup_group.assert_called_once()
+
+
+@patch("mempalace.dedup.dedup_source_group")
+@patch("mempalace.dedup.get_source_groups")
+@patch("mempalace.dedup.chromadb")
+def test_dedup_palace_with_wing(mock_chromadb, mock_groups, mock_dedup_group, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 10
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    mock_groups.return_value = {}
+    dedup.dedup_palace(palace_path=str(tmp_path), wing="test_wing", dry_run=True)
+    mock_groups.assert_called_once_with(mock_col, 5, None, wing="test_wing")
+
+
+@patch("mempalace.dedup.dedup_source_group")
+@patch("mempalace.dedup.get_source_groups")
+@patch("mempalace.dedup.chromadb")
+def test_dedup_palace_no_groups(mock_chromadb, mock_groups, mock_dedup_group, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 3
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    mock_groups.return_value = {}
+    dedup.dedup_palace(palace_path=str(tmp_path), dry_run=True)
+    mock_dedup_group.assert_not_called()
diff --git a/tests/test_repair.py b/tests/test_repair.py
new file mode 100644
index 0000000..604b0fb
--- /dev/null
+++ b/tests/test_repair.py
@@ -0,0 +1,266 @@
+"""Tests for mempalace.repair — scan, prune, and rebuild HNSW index."""
+
+import os
+from unittest.mock import MagicMock, patch
+
+
+from mempalace import repair
+
+
+# ── _get_palace_path ──────────────────────────────────────────────────
+
+
+@patch("mempalace.repair.MempalaceConfig", create=True)
+def test_get_palace_path_from_config(mock_config_cls):
+    mock_config_cls.return_value.palace_path = "/configured/palace"
+    with patch.dict("sys.modules", {}):
+        # Force reimport to pick up the mock
+        result = repair._get_palace_path()
+    assert isinstance(result, str)
+
+
+def test_get_palace_path_fallback():
+    with patch("mempalace.repair._get_palace_path") as mock_get:
+        mock_get.return_value = os.path.join(os.path.expanduser("~"), ".mempalace", "palace")
+        result = mock_get()
+        assert ".mempalace" in result
+
+
+# ── _paginate_ids ─────────────────────────────────────────────────────
+
+
+def test_paginate_ids_single_batch():
+    col = MagicMock()
+    col.get.return_value = {"ids": ["id1", "id2", "id3"]}
+    ids = repair._paginate_ids(col)
+    assert ids == ["id1", "id2", "id3"]
+
+
+def test_paginate_ids_empty():
+    col = MagicMock()
+    col.get.return_value = {"ids": []}
+    ids = repair._paginate_ids(col)
+    assert ids == []
+
+
+def test_paginate_ids_with_where():
+    col = MagicMock()
+    col.get.return_value = {"ids": ["id1"]}
+    repair._paginate_ids(col, where={"wing": "test"})
+    col.get.assert_called_with(where={"wing": "test"}, include=[], limit=1000, offset=0)
+
+
+def test_paginate_ids_offset_exception_fallback():
+    col = MagicMock()
+    # First call raises, fallback returns ids, second fallback returns empty
+    col.get.side_effect = [
+        Exception("offset bug"),
+        {"ids": ["id1", "id2"]},
+        Exception("offset bug"),
+        {"ids": ["id1", "id2"]},  # same ids = no new = break
+    ]
+    ids = repair._paginate_ids(col)
+    assert "id1" in ids
+
+
+# ── scan_palace ───────────────────────────────────────────────────────
+
+
+@patch("mempalace.repair.chromadb")
+def test_scan_palace_no_ids(mock_chromadb, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 0
+    mock_col.get.return_value = {"ids": []}
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    good, bad = repair.scan_palace(palace_path=str(tmp_path))
+    assert good == set()
+    assert bad == set()
+
+
+@patch("mempalace.repair.chromadb")
+def test_scan_palace_all_good(mock_chromadb, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 2
+    # _paginate_ids call
+    mock_col.get.side_effect = [
+        {"ids": ["id1", "id2"]},  # paginate
+        {"ids": ["id1", "id2"]},  # probe batch — both returned
+    ]
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    good, bad = repair.scan_palace(palace_path=str(tmp_path))
+    assert "id1" in good
+    assert "id2" in good
+    assert len(bad) == 0
+
+
+@patch("mempalace.repair.chromadb")
+def test_scan_palace_with_bad_ids(mock_chromadb, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 2
+
+    def get_side_effect(**kwargs):
+        ids = kwargs.get("ids", None)
+        if ids is None:
+            # paginate call
+            return {"ids": ["good1", "bad1"]}
+        if "bad1" in ids and len(ids) == 1:
+            raise Exception("corrupt")
+        if "good1" in ids and len(ids) == 1:
+            return {"ids": ["good1"]}
+        # batch probe — raise to force per-id
+        raise Exception("batch fail")
+
+    mock_col.get.side_effect = get_side_effect
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    good, bad = repair.scan_palace(palace_path=str(tmp_path))
+    assert "good1" in good
+    assert "bad1" in bad
+
+
+@patch("mempalace.repair.chromadb")
+def test_scan_palace_with_wing_filter(mock_chromadb, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 1
+    mock_col.get.side_effect = [
+        {"ids": ["id1"]},  # paginate
+        {"ids": ["id1"]},  # probe
+    ]
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    repair.scan_palace(palace_path=str(tmp_path), only_wing="test_wing")
+    # Verify where filter was passed
+    first_call = mock_col.get.call_args_list[0]
+    assert first_call.kwargs.get("where") == {"wing": "test_wing"}
+
+
+# ── prune_corrupt ─────────────────────────────────────────────────────
+
+
+@patch("mempalace.repair.chromadb")
+def test_prune_corrupt_no_file(mock_chromadb, tmp_path):
+    # Should print message and return without error
+    repair.prune_corrupt(palace_path=str(tmp_path))
+
+
+@patch("mempalace.repair.chromadb")
+def test_prune_corrupt_dry_run(mock_chromadb, tmp_path):
+    bad_file = tmp_path / "corrupt_ids.txt"
+    bad_file.write_text("bad1\nbad2\n")
+    repair.prune_corrupt(palace_path=str(tmp_path), confirm=False)
+    # No chromadb calls in dry run
+    mock_chromadb.PersistentClient.assert_not_called()
+
+
+@patch("mempalace.repair.chromadb")
+def test_prune_corrupt_confirmed(mock_chromadb, tmp_path):
+    bad_file = tmp_path / "corrupt_ids.txt"
+    bad_file.write_text("bad1\nbad2\n")
+
+    mock_col = MagicMock()
+    mock_col.count.side_effect = [10, 8]
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    repair.prune_corrupt(palace_path=str(tmp_path), confirm=True)
+    mock_col.delete.assert_called_once()
+
+
+@patch("mempalace.repair.chromadb")
+def test_prune_corrupt_delete_failure_fallback(mock_chromadb, tmp_path):
+    bad_file = tmp_path / "corrupt_ids.txt"
+    bad_file.write_text("bad1\nbad2\n")
+
+    mock_col = MagicMock()
+    mock_col.count.side_effect = [10, 8]
+    # Batch delete fails, per-id succeeds
+    mock_col.delete.side_effect = [Exception("batch fail"), None, None]
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    repair.prune_corrupt(palace_path=str(tmp_path), confirm=True)
+    assert mock_col.delete.call_count == 3  # 1 batch + 2 individual
+
+
+# ── rebuild_index ─────────────────────────────────────────────────────
+
+
+@patch("mempalace.repair.chromadb")
+def test_rebuild_index_no_palace(mock_chromadb, tmp_path):
+    nonexistent = str(tmp_path / "nope")
+    repair.rebuild_index(palace_path=nonexistent)
+    mock_chromadb.PersistentClient.assert_not_called()
+
+
+@patch("mempalace.repair.shutil")
+@patch("mempalace.repair.chromadb")
+def test_rebuild_index_empty_palace(mock_chromadb, mock_shutil, tmp_path):
+    mock_col = MagicMock()
+    mock_col.count.return_value = 0
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    repair.rebuild_index(palace_path=str(tmp_path))
+    mock_client.delete_collection.assert_not_called()
+
+
+@patch("mempalace.repair.shutil")
+@patch("mempalace.repair.chromadb")
+def test_rebuild_index_success(mock_chromadb, mock_shutil, tmp_path):
+    # Create a fake sqlite file
+    sqlite_path = tmp_path / "chroma.sqlite3"
+    sqlite_path.write_text("fake")
+
+    mock_col = MagicMock()
+    mock_col.count.return_value = 2
+    mock_col.get.return_value = {
+        "ids": ["id1", "id2"],
+        "documents": ["doc1", "doc2"],
+        "metadatas": [{"wing": "a"}, {"wing": "b"}],
+    }
+
+    mock_new_col = MagicMock()
+    mock_client = MagicMock()
+    mock_client.get_collection.return_value = mock_col
+    mock_client.create_collection.return_value = mock_new_col
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    repair.rebuild_index(palace_path=str(tmp_path))
+
+    # Verify: backed up sqlite only (not copytree)
+    mock_shutil.copy2.assert_called_once()
+    assert "chroma.sqlite3" in str(mock_shutil.copy2.call_args)
+
+    # Verify: deleted and recreated with cosine
+    mock_client.delete_collection.assert_called_once_with("mempalace_drawers")
+    mock_client.create_collection.assert_called_once_with(
+        "mempalace_drawers", metadata={"hnsw:space": "cosine"}
+    )
+
+    # Verify: used upsert not add
+    mock_new_col.upsert.assert_called_once()
+    mock_new_col.add.assert_not_called()
+
+
+@patch("mempalace.repair.shutil")
+@patch("mempalace.repair.chromadb")
+def test_rebuild_index_error_reading(mock_chromadb, mock_shutil, tmp_path):
+    mock_client = MagicMock()
+    mock_client.get_collection.side_effect = Exception("corrupt")
+    mock_chromadb.PersistentClient.return_value = mock_client
+
+    repair.rebuild_index(palace_path=str(tmp_path))
+    mock_client.delete_collection.assert_not_called()