From 8393236a5cdb85fe4c83a2d19a533e29a7091007 Mon Sep 17 00:00:00 2001
From: jsboige <jsboige@gmail.com>
Date: Tue, 15 Sep 2026 02:06:02 +0200
Subject: [PATCH] Fix: lane_claim step died silent under bash -e before
 printing its verdict

The blocking lane_claim step in always-on-guards.yml runs under the
runner's default shell (bash -e -o pipefail); its own `set -uo pipefail`
does NOT remove -e. An unguarded `python3 lane_claim_required.py ...`
followed by `RC=$?` died immediately on any non-zero exit (1 = legitimate
BLOCK, 2 = caller error) -- before the verdict was printed and before the
resolution comment (RELEASED / OVERRIDE / 48h) was posted. Every lane
collision surfaced as a mute step failure diagnosed by hand (measured on
#15846, run of 2026-09-13).

Fix: the canonical guard of the sibling gates (variation_prev_guard,
variation_adjacency_guard): `&& RC=0 || RC=$?`. Verified by replaying the
step core under the exact runner shell with a mock helper: exits 0/1/2 all
reach the verdict block now; pass exits 0, block prints ::error with the
reason and posts the resolution comment. Sibling gates already had the
guard -- lane_claim was the single unguarded occurrence.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
---
 .github/workflows/always-on-guards.yml | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/always-on-guards.yml b/.github/workflows/always-on-guards.yml
index f527dc380a..eee6e97dec 100644
--- a/.github/workflows/always-on-guards.yml
+++ b/.github/workflows/always-on-guards.yml
@@ -1077,10 +1077,17 @@ jobs:
             echo "::warning::closingIssuesReferences fetch failed; falling back to regex finder (#10323)."
           fi
 
+          # Le shell par defaut du runner est `bash -e -o pipefail` ; le
+          # `set -uo pipefail` ci-dessus n'y retire PAS -e. Sans le guard
+          # `&& RC=0 || RC=$?` (la convention des gardes freres
+          # variation_prev_guard / variation_adjacency_guard ci-dessus), un
+          # exit non nul du helper (1 = BLOCK legitime, 2 = caller error)
+          # tuait le step AVANT l'affichage du verdict et le commentaire de
+          # resolution (RELEASED/OVERRIDE/48 h) : blocage muet, diagnostique
+          # a la main sur #15846.
           python3 scripts/ci/lane_claim_required.py \
             --body-file /tmp/pr_body.txt "${PR_CREFS_ARG[@]}" \
-            > /tmp/verdict.json 2>/tmp/verdict.err
-          RC=$?
+            > /tmp/verdict.json 2>/tmp/verdict.err && RC=0 || RC=$?
 
           if [ -s /tmp/verdict.err ]; then
             echo "--- helper stderr ---"