D245 — Search indexes follow the files

Decision. The in-memory and SQLite search indexes are kept fresh by validation, the same way as the link graph (D241). Before every search, after every git pull and on reindex, the graph cache reports every concept whose resolved content changed, appeared or vanished since the previous reconciliation (kb.ConceptChanges). One per-KB reconciler applies that delta to both indexes. No write path updates an index any more.

Why. Every write handler used to notify the indexes itself, and some forgot: conflict_resolve and git_conflict_resolve never did, a server without SQLite never saw a git pull until it restarted, and an operator's editor was seen only after a manual reindex. Validation covers all of these with one mechanism, with or without git and with or without SQLite. It costs one stat walk per search, a few milliseconds and no file reads when nothing changed.

Alternatives rejected. - Keep notifying, and fix the handlers that forget: it fixes today's list, and the next handler that writes a file would forget again. D243 had just added the same kind of fix to supersede. - A hook in kb.WriteConcept: it does not see every change. Moves and collapses change files with os.Rename/os.Remove, and pulls and editors never call it. - A hook on gitWrap's commit: git may be disabled, and CommitOp returns early when auto-commit is off. - Validate after every write: that is a stat walk per write that no reader asked for. Validating on the read path costs a walk only when someone searches.

Consequences. reindex without full works without SQLite and is the same reconciliation a search runs. concept_batch no longer has an index step inside its rollback boundary, because the files are the only state to restore. The cache still holds no bodies: a change carries the content the validation just read, and a second read happens only for a file the validation reused. The offline ReconcileIndex stays for the CLI and the startup check, which also drops SQLite rows for concepts removed while the server was down. TestIndexUpdatesOnlyInReconciler fails if any other code in internal/mcpserver updates an index.