Why: cmd_close posted the PR with a single curl wrapped in
2>/dev/null || true, so any transient TLS/timeout on the git-home
HTTPS surface left the card-close branch pushed with no PR and no
diagnostics; this hit three times on 2026-09-30 and each needed a
manual API call to recover.
Evidence: bash -n clean; stub-server harness running the block
verbatim (sed-extracted from this file, executed inside the worktree
branch context): ok mode recovers the PR URL on first POST; exists
mode (POST always 500) retries 4x with visible stderr then recovers
the pre-existing open PR via GET ?state=open matching head ref;
fail mode against the retired git-panel host shows four visible
retry notices and falls through to the existing [next] hint.
Impact: scripts/task.sh cmd_close only; precheck/start/sync/finish
untouched; card-close merge authority unchanged (owner merges).
post-merge hook and task-finish auto-close inherit the fix through
the same function.
Refs: task card fix-close-pr-retry
weichen
888aa9471c