row 269 (264b, #1774): BUILD.md drops the planned bindLaunch session-running refusal. Two old tests bind a second unended run to one session and expect the claim refusal (threads.test.mjs:88-89, sessions.test.mjs:119-120), so the broker half of the fence is the existing per-session claim, thread-already-held (broker.mjs:4815)

agents/gizmoduck/work/queue-269/BUILD.md

@@ -146,9 +146,12 @@ with `id` = the thread id (3k-3l.sql:50-51). The rule reads only an immutable ro
   `#threadRows` joins `sessions` in place of `session_defaults` (broker.mjs:868-896).
 - `threadIdle(record)`: same keys. The row is the one for the session the run was bound to
   (`#runs` entry, broker.mjs:927), so a run is idled against its own session.
-- `bindLaunch`: a new run on a session that another unended run in this broker is bound to refuses
-  `session-running`. That's the broker half of the fence for two launcher processes. A rebind of an
-  existing run (`recover()`) skips the check, as it skips the harness check now.
+- `bindLaunch`: no new refusal. It already takes `session` and puts it in the body (broker.mjs:945).
+  The broker half of the single-writer fence is the per-session claim that exists now:
+  a second claim on a held session refuses `thread-already-held` (broker.mjs:4815). A
+  `session-running` refusal at bind would break two old tests that bind a second unended run to one
+  session and then expect the claim refusal (threads.test.mjs:88-89, sessions.test.mjs:119-120).
+  The launcher's registry check and the workspace lock are the host halves.
 
 ### Seat