ci(test-core): the Test Core shard wall is 50, so both stall-guard verdicts land before it

.github/workflows/ci.yml

@@ -478,31 +478,44 @@ jobs:
     # margin for a cold Turbo cache; the old 45 left a hung job "running" for
     # half an hour past any plausible healthy finish.
     #
-    # ⚠ RAISED 30 -> 45 (#16173), and the raise is still load-bearing. It was
-    # made because shard 5/6 was being killed at the 30-minute wall (12+
-    # observations at 30:16-30:21 with every other job green; the green band
-    # topped out at 28:56, a ~1 minute margin), and so the tail could be
-    # measured uncensored before anyone re-derived
-    # `scripts/test-shard-timings.json`. Both are done: the dataset was
-    # refreshed (#20388, then #21826) and the split ran the whole CLI alone on
-    # shard 1/6 (#21487) until #22075 cut it into 3 slices. HELD at 45 by that
-    # change: the re-size is owed after it lands, from the measured post-change
-    # Test Core job walls, never from a prediction (#22075 carries it).
+    # History: RAISED 30 -> 45 (#16173) while one shard ran the whole CLI and
+    # was killed at the 30-minute wall; held at 45 until #22075 cut the CLI
+    # into 3 slices (5919483472).
     #
-    # ⛔ REVERT CONDITION, restated against measured wall time, not a card:
-    # back to `30` only when the slowest shard's JOB wall time stays at or
-    # under 24 minutes (80% of 30, so the margin the old wall lacked is
-    # there) on every scheduled run for a week. It does not today. On the 16
-    # main runs after the #21826 refresh (37413386379 to 37467882762), shard
-    # 1/6 — the CLI alone — read 6m14s-35m43s of job wall time, over 30
-    # minutes on 9 of them (34m39s run 37415122516, 35m43s run 37453598388,
-    # 34m08s run 37460325624), so the condition as first written ("once
-    # #16173 lands") would now kill that shard; and its slowest reading is
-    # already 79% of this 45. Read the `Test Core (1/6)` job's started and
-    # completed times before touching this value. It carries no other expiry
-    # — a raise with no revert condition beside it becomes permanent by
+    # ⚠ RE-SIZED 45 -> 50 (#22075), derived so that BOTH stall-guard verdicts
+    # land before this wall on every observed run. Window: every completed,
+    # non-cancelled CI run whose tested tree carries 5919483472, runs
+    # 37917885267 to 37956350887 (2026-10-09 10:29Z-16:03Z): 5 schedule,
+    # 6 push, 30 merge_group and 25 pull_request runs, 396 `Test Core (N/6)`
+    # jobs; 24 cancelled runs excluded. Slowest job wall per event, in
+    # minutes: schedule 21.0, push 20.9, merge_group 24.1, pull_request 27.1;
+    # p90 of all 396 is 22.0. Measured with
+    # `node scripts/measure-stall-guard-headroom.mjs` over those jobs, the
+    # worst p + s (job start to the end of "Run this shard's tests") is
+    # 26m38s, on run 37923333449 `Test Core (3/6)`. Three readings set the
+    # value, and the largest answer wins:
+    #   * the window verdict, a silent freeze killed 10m after the last
+    #     output: p + s + 10m = 36m38s;
+    #   * the cap-deferred verdict, when the liveness probe sees the suite
+    #     still writing: p + s + 20m = 46m38s, inside 50 by 3m22s. It missed
+    #     45 on 8 of the 396 jobs and would miss 40 on 60;
+    #   * the 80% wall margin: the slowest job wall, 27m05s on that same job
+    #     (70 packages executed, the CLI as all 3 slices), is within 80% of
+    #     50 (40.0).
+    #
+    # ⛔ REVERT CONDITION, restated against measurement, not a card: a value
+    # below 50 is allowed only when, on a re-measured window of Test Core
+    # runs (`node scripts/measure-stall-guard-headroom.mjs` over the jobs
+    # payloads of every completed pull_request, merge_group, push and
+    # schedule run in it), BOTH guard verdicts -- the window path
+    # (p + s + 10m) and the cap-deferred path (p + s + 20m) -- land before the
+    # new value on every observation, AND the slowest `Test Core (N/6)` job
+    # wall is at or under 80% of it. Read the pull_request and merge_group
+    # runs, not the hourly schedule alone: scheduled runs mostly replay the
+    # cache their commit's push run saved. It carries no other expiry — a
+    # raise with no revert condition beside it becomes permanent by
     # forgetting — and the stall guard stays the primary hang detector.
-    timeout-minutes: 45
+    timeout-minutes: 50
     permissions:
       contents: read
     strategy: