check_vision_requirements (and five siblings: browser_vision, image/video
generation, x_search, browser_vault) wrapped their whole probe in
`except Exception: return False`. The registry then logged "returned False",
indistinguishable from an unconfigured backend, and the only diagnostic for a
crashed resolver was gone (#87950: named custom provider lookup failing in a
long-lived multi-profile process, reported as vision tools silently vanishing).
The registry owns the verdict: _run_check_fn_uncached and _check_fn_cached both
catch, log with traceback, and return False. Let the exception reach them.
Behaviour for the model is unchanged (tool hidden either way); agent.log now
says why.
For each issue anchor present in BASE 63279301bc non-test .py and absent on HEAD, the BASE comment/docstring block was re-attached at the HEAD location of the code it explained (matched by the distinctive code line / enclosing def). Sentences already covered by an existing HEAD comment were deduped; the issue number always survives. Insert-only: no code lines changed.
Repo scanners (check_subprocess_stdin, check-windows-footguns --all) flagged 21 sites where
the r3 single-line collapses lost stdin=DEVNULL, encoding='utf-8'/errors='replace', the
'# windows-footgun: ok' same-line marker, or the getattr(os, 'geteuid') gate. Each guard is
restored at the call site (real portability/hang fixes, not suppressions).
