2.3.0 — the index train: local-first recall index, incremental sweep, stemming + alias expansion

One schema-bump release (recall-index schema 3, entity-index schema 2; old
recall indexes rebuild automatically, no vault migration):

- Local-first recall index: the live BM25 index lives in the machine state dir
  (keyed by endpoint hash); capture's upkeep is a zero-network atomic file
  write, no advisory lock — replacing the O(vault) GET/PUT-whole-index round
  trip per write. The vault copy is a snapshot (sweep + session-end) used to
  seed fresh machines / catch up after another client swept
  (ECHO_RECALL_SYNC_HOURS, default 24). The read path never PUTs the vault.
- Incremental sweep: entity + recall meta carry 16-char content hashes;
  `sweep --fast` fetches only new/gone/hash-missing notes plus a rotating
  weekday shard (--all-shards forces everything); deletions drop from both
  indexes; index-only so no --apply gate. `load` auto-runs it past
  ECHO_FAST_SWEEP_DAYS (7); doctor reports index freshness. Obsidian-side
  edits now reach the indexes without manual maintenance.
- Stemming + alias expansion: echo_stem.py (conservative Porter-lite, unit-
  tested families + over-stemming guards) applied at index AND query time;
  a query fuzzy-matching an entity folds its title/alias vocabulary into the
  BM25 query at half weight — expansion can only boost docs containing the
  terms. capture hashes the note's FINAL content (auto-link reordered first).

Eval gold set 8 -> 14 queries (6 paraphrases): recall@5/MRR 1.00/1.00 vs
keyword baseline 0.75/0.79. +3 unit tests, +10 e2e; test harnesses now isolate
ECHO_STATE_DIR. All seven suites green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

echo-memory.plugin.src/skills/echo-memory/scripts/echo_doctor.py

@@ -74,6 +74,18 @@ def run_op() -> dict:
             else:
                 line(status < 400, "marker fetch", f"HTTP {status}")
 
+    # Index freshness (2.3) — informational, never red: how stale this machine's
+    # local indexes are (the fast sweep trues them up at load past 7 days).
+    if fatal is None:
+        try:
+            import sweep as sweep_mod
+            age = sweep_mod.fast_sweep_age_days()
+            line(True, "index freshness",
+                 f"last local sweep {age:.1f}d ago" if age is not None
+                 else "no local sweep yet — runs automatically at the next load")
+        except Exception:  # noqa: BLE001
+            pass
+
     reds = sum(1 for c in checks if not c["ok"])
     return {"ok": reds == 0 and fatal is None, "action": "doctor",
             "endpoint": cfg["endpoint"], "fatal": fatal, "reds": reds, "checks": checks}