row 264a r13 (#1769): BUILD.md writes M2's four edits before phase 4 reruns: the receive filter, delivery_same_session dropped from 3k-3l.sql and schema.sql, and store.mjs's SCHEMA_SHA256 set to the mutated schema; a kill counts only as a receive-test assertion; doc only (mos-1279, sage-2688, sage-2690, duckworth-0143, duckworth-0144)

agents/gizmoduck/work/queue-264/BUILD.md

@@ -201,11 +201,27 @@ Each runs on a copy of the candidate tree with one edit, and the named test must
   run's fence entirely, so the kill shows the refusal is tested, not that generations add a check.
   A mutant that puts back `h.holder_run !== s.run` survives by equivalence. That isn't a coverage
   gap.
-- M2. In `message.receive`, drop the `mt.session=?` filter (the session clause and its argument).
-  Killed by sessions.test T1, where a1 would take the second session's message.
+- M2 (mos-1279, sage-2688, sage-2690). Four edits, and the restore sha check covers all four files:
+  1. broker.mjs:5251, in `message.receive`: drop the `mt.session=?` filter (the session clause and
+     its argument).
+  2. 3k-3l.sql: drop the `delivery_same_session` trigger.
+  3. schema.sql: drop the same trigger.
+  4. store.mjs:16: set `SCHEMA_SHA256` to the sha256 of the mutated schema.sql, with the replace
+     sessions.test:432 uses. store.mjs:94 checks schema.sql against it at import (duckworth-0144).
+     `LEGACY_SHA256` stays. The chain check at :117 holds because both SQL files drop the trigger.
+  Without edits 2-4, the trigger refuses #delivery's INSERT first. request() then returns
+  storage-refused before any assertion runs. That happened at r13 (duckworth-0143).
+  A kill counts only as an assertion in a test that exercises receive: sessions.test T1 :89, T7 :422,
+  or another receive assertion the log names. A failure only at the trigger's own pin (:164-170)
+  doesn't count, and neither does a thrown error. The killing test is expected to be T1, where a1
+  would take the second session's message.
 - M3. In 3k-3l.sql, count every claim row for `generation` instead of `op='claim'` rows only.
   Killed by sessions.test T7, generations 1, 1, 1, 2, 2.
 
+Phase 4 rerun on r13 (mos-1279, sage-2688). The r13 gate's phases 1-3 carry. M1-M4 rerun whole on
+2cc34aef8 plus this note, each under `timeout -k 10 300` (Run limits). Any survivor, throw or
+non-receive kill goes to Mos unplaced.
+
 ### Dry run
 
 Before writing any node test, I ran 3j-3k.sql in an in-memory Python sqlite3 on a 3j fixture