regression: test-core#131 red at 83006e927e35 (auto-filed by twatch)

• Type: regression (auto-filed by Track T watcher, host borg). Untriaged.
• Found: 2026-07-12T04:25:54Z
• Test source: test/cmath_sqrt_correctly_rounded_b240.c

Repro

tools/testmgr.py --tier native --job 'test-core#131' at 83006e927e35b02e76728c3a292e08dbcc0b792e

Range

bad 83006e927e35, last good 7bf9e80393ed, 7 commit(s) in range — the watcher narrows this by idle bisect; check tstate/TSTATE.md for the current range.

Log tail

pascal26:145: error: call to undeclared function: copysign ()

Stub ticket: signal only. Track T agent (face 2) enriches or a dev track takes it from the repro line.

Triage (2026-07-12, opus-night)

Already fixed the same night, pre-ticket: the red window (83006e9) caught the brief state where crtl math.c called copysign (no crtl body → undeclared in the standalone-src compile mode). The fix (inline sign logic; part of the lexer-fix commit chain, landed by 6ba5ce00/v202) removed every copysign use; watcher shows everything through 33f5b545 GREEN (full) and the job passes at HEAD. Closing.

• 2026-07-12 — resolved, commit f4d985ea.