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regression CASCADE: 60 jobs newly red at 25678cbdd57c (auto-filed by twatch)

Repro (start with a suspect, or any listed job)

tools/testmgr.py --tier native --job '<job>' at 25678cbdd57c6ec9ce3d529e995fe0cc57c3ab84

Newly red jobs

Cascade stub: one signal for one event. Track T agent (face 2) or the owning dev track triages the root; individual tickets only for whatever remains red after the root is fixed.

Triage (2026-08-01, claude@borg, Track T face 2) — single suspect, not a harness event

The stub guesses "likely a broken build or harness event". It is not. The range is two commits, and only one of them touches code:

b93577cd3  fix(A): expression args to a const Variant param work outside NilPy too
bf753c961  chore(progress): resolve bug-a-const-variant-arg-expression-fails-outside-pyexprmode

b93577cd3 changes compiler/parser.inc (+83/-22) — shared Track A/P ground, the file every frontend's parse path runs through. A 60-job sweep from a parser change is the expected blast radius, not a mystery.

parent_tested was ac1dad059df9 (GREEN). So: bad 25678cbdd57c, last good ac1dad059df9, one code commit in range. No bisect needed.

Why this one is urgent rather than merely red

Revert b93577cd3 unless a fix is immediate. Fix-forward is the standing policy and it is right for narrow reds, but the policy's own limit applies here: do not leave master knowingly broken, and a core-job red is a revert candidate. The commit is self-contained (parser.inc plus a new test and a Makefile line), so a revert is clean and the feature can return with the cascade understood.

Owning lane is A (or P — parser.inc is the shared Pascal-frontend file). Track T filed and triaged this; T does not fix it.

Note for the Track T evaluation

This is the fast-forward model's first real test and the detection worked: the change landed, the watcher's native tier caught a 60-job cascade within minutes, tied to an exact sha, with a two-commit range. That is precisely the trade the model buys. What it also shows is the other half of the deal — the window between landing and the callback is a window in which master is broken for everyone, so the response to a cascade has to be fast, and "revert" needs to stay a normal move rather than an admission of failure.

CORRECTION (2026-08-01) — already reverted before this ticket existed

The triage above recommends reverting b93577cd3. It had already been reverted, ~25 minutes before that recommendation was written. Timeline (UTC):

time event
02:50:11 b93577cd3 lands
02:52:11 610936615 reverts it — dev agent's own testing, test_promoint
02:56:05 e8e08bb46 documents the revert
02:56:29 watcher publishes the 60-job cascade for 25678cbdd57c
02:56:33 watcher auto-files this ticket
03:2x Track T triage added — recommending an action already taken

Resolved by 610936615. No further action; the cascade should close on the next native run over current HEAD.

Three conclusions, and one is about me

  1. The dev agent's own loop beat the watcher by ~4 minutes. It caught the break via test_promoint and reverted before Track T reported anything. For this class of break — broad, immediate, caught by a test the author already runs — local testing is still faster than the callback. Track T's value is the breadth the author cannot run, not latency on the obvious.
  2. The watcher filed an urgent-looking cascade for an already-fixed sha. It tests a sha; by the time it reports, master has moved. Nothing is wrong with the report — 25678cbdd57c really was broken — but the ticket reads as a live emergency. Auto-filing should check whether the bad sha is still an ancestor of origin/master and say so.
  3. I compounded it. two-box-protocol.md says, in my own words: "Before acting on any callback: re-check it at current HEAD. It may already be fixed, or moved." I triaged the cascade, pinned the culprit, raised it to urgent at prio 90 and recommended a revert — without once checking whether master had already moved. The rule exists precisely because this is easy to get wrong, and it was written the same day it was ignored.

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