v0.37.1.0 feat: brainstorm + lsd — bisociation idea generator grounded in your own brain (#1214)

* feat: brainstorm + lsd (v0.37 wave, pre-merge snapshot)

Brainstorm + LSD bisociation idea generator. Will rebase + bump after master merge.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* docs: CHANGELOG voice tightening — strip meta-content from v0.37.1.0 entry

CLAUDE.md gains an IRON RULE for CHANGELOG entries: the changelog describes
what the user gets, not how the work happened. No mentions of review
processes, plan files, decision tags, migration version drama, or 'what we
caught and fixed before merging.' If a fact only exists because of the
development workflow, it does not belong in release notes.

Rewrite v0.37.1.0 entry to comply: cut the 'what we caught' section
(architectural review drama), the 'plan + reviews' bullet, and the
migration-renumbering aside. Entry shrinks 67 → 56 lines, every sentence
now answers 'what can I do / how do I use it / what should I watch for.'

Regenerated llms-full.txt to absorb the CLAUDE.md voice update.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

src/schema.sql

@@ -99,6 +99,11 @@ CREATE TABLE IF NOT EXISTS pages (
   effective_date_source TEXT,
   import_filename       TEXT,
   salience_touched_at   TIMESTAMPTZ,
+  -- v0.37.0 (migration v79): real stale-page signal for `gbrain lsd`. Bumped
+  -- by op-layer write-back inside `search`/`query`/`get_page` op handlers
+  -- (NOT inside engine methods — internal callers must not pollute the
+  -- signal). NULL = never retrieved (LSD prioritizes these first).
+  last_retrieved_at     TIMESTAMPTZ,
   CONSTRAINT pages_source_slug_key UNIQUE (source_id, slug)
 );
 
@@ -116,6 +121,13 @@ CREATE INDEX IF NOT EXISTS idx_pages_source_id ON pages(source_id);
 -- stays low. Don't add a regular `(deleted_at)` index without measuring.
 CREATE INDEX IF NOT EXISTS pages_deleted_at_purge_idx
   ON pages (deleted_at) WHERE deleted_at IS NOT NULL;
+-- v0.37.0: full B-tree index on last_retrieved_at supports LSD's stale-page
+-- query `WHERE last_retrieved_at IS NULL OR last_retrieved_at < NOW() -
+-- INTERVAL '90 days'`. Postgres handles NULL in B-tree indexes (sorted to
+-- one end) so one index covers both branches. A partial WHERE NOT NULL
+-- would miss the NULL branch that LSD prioritizes (codex round 2 #6).
+CREATE INDEX IF NOT EXISTS pages_last_retrieved_at_idx
+  ON pages (last_retrieved_at);
 -- v0.29.1: expression index used by since/until date-range filters that read
 -- COALESCE(effective_date, updated_at). A partial index on effective_date
 -- alone would NOT help — the planner can't use it for the negative side of