Files
BFM-decomp/tools
Drew T 30caa67127 fix(r22 guard): record liveness, do not infer it — my mtime heuristic failed BOTH ways
I shipped a guard that used drafting-scratch mtimes as a liveness proxy. It failed
in both possible directions within minutes:

* FALSE PASS: the find included '.run/*wave*', which expanded past ARG_MAX
  ('Argument list too long'). find then matched nothing, the guard PASSED, and I
  ran clean: removed build/, expected/, and the regenerated splat tree (asm/, assets/, include macros, undefined_*_auto.txt). on a live lane — deleting asm/ under five drafting agents. I
  restored it immediately (extract-all 212/212) but that is damage control, not a
  design.
* FALSE PASS, structurally: even with the glob fixed, an agent that THINKS longer
  than the window is indistinguishable from a finished one — the exact flaw I had
  already written into gater_lane's docstring for the verdicts file ('a quiet file
  mtime is deliberately NOT accepted as one') and then rebuilt here anyway.

tools/lane_inflight.py is the fix: liveness is RECORDED, not inferred. The
orchestrator adds a target when it launches the workflow and removes it when the
verdict returns — both actions it already performs, so the ledger cannot drift
without skipping a step that is taken anyway.  exits non-zero when any agent
is live, which IS the guard, and both r22_verify.sh and parallel_gate --r22 now use
it instead of touching the filesystem.

Negative-controlled both directions: refuses with 5 live agents named and their
start times; passes when the ledger is drained.

The lesson worth more than the fix: I had already identified 'a quiet mtime is not
a completion signal' as a defect class, documented it, and then re-implemented it
in a different file. Writing a rule down does not stop you applying its opposite
somewhere else.
2026-08-31 18:59:50 -06:00
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