Code scanning alert 71 (actions/untrusted-checkout/high) has stayed open
against main at the `Checkout PR branch` step — the same step #1966 added
the `is_fork == 'false'` guard to. The rule is syntactic, so it cannot see
that guard, the job-level author_association check, or the repo's
`collaborators_only` fork-PR policy; no hardening around the step clears it
while the step exists.
The step turns out to be redundant anyway. claude-code-action fetches and
checks out the PR branch itself, and its own docs name a bare base-ref
checkout as the preferred pattern — which is what upstream's own claude.yml
does. Our lookup-then-checkout pair is vestigial from the v1 example
workflow inherited in #1869.
So: delete the PR-head checkout, make the base checkout unconditional, and
drop the now-unused `sha` output. The `is_fork` gate on Run Claude Code
stays, and is now the only thing keeping fork code out of the workspace —
the action fetches a cross-repository head via refs/pull/N/head on its own.
Closes#2069
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JTHVxSu8AUgHRLvo1ntZ8H
Signed-off-by: cliffhall <cliff@futurescale.com>