fix: prevent firstmate pr targeting upstream

[JTInventory]

Intent

Ship a narrow Firstmate-owned guard so no-mistakes and PR creation for this repository cannot accidentally open or update PRs against kunchenguid/firstmate. The intended target is the captain fork JTInventory/firstmate. The change should use the concrete evidence that intended PR #30 was on JTInventory/firstmate and duplicate upstream PR kunchenguid#171 was opened on kunchenguid/firstmate, keep behavior narrow, avoid unrelated no-mistakes CI monitor, durable-profile, behavior-test runtime, watcher, secondmate routing, or fm-send changes, add focused fork-parent target tests, document only the captain fork target, and stop before PR creation if any path would target kunchenguid/firstmate.

What Changed

• Added a Firstmate no-mistakes PR target guard that allows only the captain fork JTInventory/firstmate and fails closed for upstream kunchenguid/firstmate, targetless local gates, unsafe no-mistakes remotes, and override attempts.
• Wired the guard into no-mistakes configuration and documented when to run it before Firstmate no-mistakes push or PR creation paths.
• Added focused shell coverage for safe captain-fork targets and blocked upstream, parent-gate, push URL, and override cases.

Risk Assessment

✅ Low: Captain, the change is narrow, fail-closed, and covered by focused behavior tests for the target-bypass cases reviewed here.

Testing

The prompt-provided baseline had already passed; I then exercised the focused fork-parent guard suite, captured manual operator-facing accept/block transcripts, verified the live worktree target, and reran the full configured command with the new guard prefix. All required checks passed, with intentional upstream-target cases exiting nonzero and printing the expected block messages.

Evidence: manual PR target guard transcript

origin	https://github.com/JTInventory/firstmate (fetch)
origin	https://github.com/JTInventory/firstmate (push)

## safe-captain-fork
$ bash -lc cd '/tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/manual-cases/safe-repo' && '/root/.no-mistakes/worktrees/76db9585a6d5/01KWEVTCZ3EBK8BCQV84XWNHHK/bin/fm-no-mistakes-pr-target-guard.sh'
exit=0
stdout:
ok: PR target repo jtinventory/firstmate verified
stderr:

## blocks-upstream-origin
$ bash -lc cd '/tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/manual-cases/upstream-origin' && '/root/.no-mistakes/worktrees/76db9585a6d5/01KWEVTCZ3EBK8BCQV84XWNHHK/bin/fm-no-mistakes-pr-target-guard.sh'
exit=1
stdout:
stderr:
blocked: would target upstream remote.origin.url=https://github.com/kunchenguid/firstmate (normalized kunchenguid/firstmate), expected jtinventory/firstmate

## blocks-upstream-gate
$ bash -lc cd '/tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/manual-cases/upstream-gate' && '/root/.no-mistakes/worktrees/76db9585a6d5/01KWEVTCZ3EBK8BCQV84XWNHHK/bin/fm-no-mistakes-pr-target-guard.sh'
exit=1
stdout:
stderr:
blocked: would target upstream no-mistakes gate remote.origin.url=https://github.com/kunchenguid/firstmate (normalized kunchenguid/firstmate), expected jtinventory/firstmate

## blocks-parent-override
$ bash -lc cd '/tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/manual-cases/parent-override' && FM_FIRSTMATE_PR_TARGET_REPO=kunchenguid/firstmate '/root/.no-mistakes/worktrees/76db9585a6d5/01KWEVTCZ3EBK8BCQV84XWNHHK/bin/fm-no-mistakes-pr-target-guard.sh'
exit=1
stdout:
stderr:
blocked: unsupported expected PR target kunchenguid/firstmate, only jtinventory/firstmate is allowed

## live-worktree
$ bash bin/fm-no-mistakes-pr-target-guard.sh
ok: PR target repo jtinventory/firstmate verified
exit=0

Evidence: focused PR target guard test output

ok - PR target guard accepts captain fork origin and no-mistakes gate
ok - PR target guard rejects parent origin target
ok - PR target guard rejects parent second origin target
ok - PR target guard rejects parent origin push URL target
ok - PR target guard rejects parent second origin push URL target
ok - PR target guard rejects parent no-mistakes gate target
ok - PR target guard rejects parent second no-mistakes gate target
ok - PR target guard rejects local no-mistakes gate without target
ok - PR target guard accepts captain fork nonlocal no-mistakes remote
ok - PR target guard rejects parent nonlocal no-mistakes remote
ok - PR target guard rejects parent nonlocal no-mistakes push URL
ok - PR target guard rejects parent expected target override
ok - PR target guard rejects parent expected target argument
ok - PR target guard rejects parent no-mistakes status target

Evidence: live worktree guard stdout

ok: PR target repo jtinventory/firstmate verified

ok: PR target repo jtinventory/firstmate verified

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

🔧 **Review** - 1 issue found → auto-fixed (4) ✅

• ⚠️ bin/fm-no-mistakes-pr-target-guard.sh:64 - The guard only inspects the first origin push URL. Git supports multiple push URLs, and git remote get-url --push origin returns one unless --all is used, so a repo with an allowed first push URL plus a second https://github.com/kunchenguid/firstmate push URL would pass while git push origin can still target the upstream repo. Iterate over all origin fetch/push URLs, and use --get-all for gate config checks too.

🔧 Fix: Check every PR target URL
1 warning still open:

• ⚠️ bin/fm-no-mistakes-pr-target-guard.sh:78 - The guard silently skips a no-mistakes remote when that remote URL is not a local directory. If origin is correctly set to JTInventory/firstmate but git push no-mistakes points directly at https://github.com/kunchenguid/firstmate, this check continues instead of blocking, so the new fail-closed guard still has a PR-target bypass. Treat a non-local no-mistakes URL as a target URL to verify, or fail closed when it cannot be inspected as a local gate.

🔧 Fix: Captain, verify no-mistakes remote targets
1 warning still open:

• ⚠️ bin/fm-no-mistakes-pr-target-guard.sh:78 - When the no-mistakes remote points at an existing directory, the guard treats it as inspected even if git --git-dir="$gate" config fails or returns no remote.origin.url / remote.origin.pushurl. Because those reads are swallowed with || true, an uninspectable or targetless local gate can still pass as ok; fail closed unless the local gate yields at least one verifiable target URL.

🔧 Fix: Fail closed on targetless local gates
2 warnings still open:

• ⚠️ bin/fm-no-mistakes-pr-target-guard.sh:83 - The guard checks remote.no-mistakes.url but never checks remote.no-mistakes.pushurl. Git uses pushurl for git push no-mistakes, so a repo with a safe no-mistakes fetch URL plus remote.no-mistakes.pushurl=https://github.com/kunchenguid/firstmate would pass this guard and still push through the upstream target. Inspect every git remote get-url --push --all no-mistakes URL too.
• ⚠️ bin/fm-no-mistakes-pr-target-guard.sh:12 - The expected target can be changed with either an argument or FM_FIRSTMATE_PR_TARGET_REPO, which creates an allowlist escape hatch for the exact upstream repo this guard is meant to block. If the captain-owned target must remain only JTInventory/firstmate, remove the override or fail closed when the expected repo normalizes to kunchenguid/firstmate.

🔧 Fix: Captain, pin PR target guard
✅ Re-checked - no issues remain.

✅ **Test** - passed

✅ No issues found.

• command -v tmux >/dev/null || { echo "tmux is required for e2e tests" >&2; exit 1; }; tmux -V; rc=0; for t in tests/*.test.sh; do echo "== $t =="; bash "$t" || rc=1; done; exit "$rc"
• Baseline already provided by the prompt: command -v tmux >/dev/null || { echo "tmux is required for e2e tests" >&2; exit 1; }; tmux -V; rc=0; for t in tests/*.test.sh; do echo "== $t =="; bash "$t" || rc=1; done; exit "$rc"
• bash tests/fm-no-mistakes-pr-target-guard.test.sh > /tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/focused-pr-target-guard-test.log 2>&1
• bash bin/fm-no-mistakes-pr-target-guard.sh > /tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/live-worktree-guard.out 2> /tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/live-worktree-guard.err
• Manual CLI evidence cases recorded in /tmp/no-mistakes-evidence/01KWEVTCZ3EBK8BCQV84XWNHHK/manual-pr-target-guard-transcript.txt: safe captain fork, blocked upstream origin, blocked upstream no-mistakes gate, blocked parent override, live worktree guard.
• command -v tmux >/dev/null || { echo "tmux is required for e2e tests" >&2; exit 1; }; bash bin/fm-no-mistakes-pr-target-guard.sh || exit 1; tmux -V; rc=0; for t in tests/*.test.sh; do echo "== $t =="; bash "$t" || rc=1; done; exit "$rc"

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.