Summary

• Adds .claude/hooks/tests/_lib-mock-gh.sh — a tiny gh-shim helper that intercepts gh issue view <N> ... --json ... calls inside hook test sandboxes and returns synthetic {"number":N,"state":"OPEN"}. Pass-through for any gh call it doesn't intercept.
• Wires the shim into test_single_closes_per_pr.sh and test_validate_pr_required_sections.sh. Both previously failed every case (0/13 and 0/8) because their PR titles reference #114 / #113, which validate-pr-create.sh rejects when those issues are CLOSED — and they are now closed upstream.
• The shim's mock_gh_set_state <sb> <num> <state> helper is available for future tests that need to exercise the CLOSED-issue branch of the validator. Not used in this PR — neither test was scoped to that branch originally.

Closes #154.

Testing

bash .claude/hooks/tests/test_single_closes_per_pr.sh
# PASS: 13   FAIL: 0

bash .claude/hooks/tests/test_validate_pr_required_sections.sh
# PASS: 8    FAIL: 0

# Full suite — all 12 test files green
for t in .claude/hooks/tests/test_*.sh; do bash "$t" 2>&1 | tail -2; done

To trace intercepted shim calls during debug: MOCK_GH_TRACE=1 bash .claude/hooks/tests/test_single_closes_per_pr.sh.

Glossary