feat(pr-gatekeeper): review a staged diff pre-push, for GitOps repos with no PR

infra#470 resolved a doctrine conflict: root rule 5 wants a PR for risk/medium+,
and mathias/infra forbids branches because Flux watches main — a branch there can
be linted but never reconciled, so a PR reviews a state that was never deployed.
The agreed lane is that such work stays on main and gets a recorded adversarial
review pass BEFORE the push.

That lane names this agent as its reviewer, and the definition only knew how to
review an open PR. A lane whose reviewer cannot see the diff resolves to "the
author was careful", which is what rule 5 was written to replace.

ONE AGENT, TWO MODES — NOT A SECOND FILE

Only three of twelve sections were PR-specific: the diff command, the CI step, and
the verdict. Everything else — the iron laws, "the test is the claim", the three
attack habits, probing without causing the incident, escalation — is diff-agnostic.
Forking a near-duplicate 226-line definition would give the estate two
implementations of one review standard, and they would drift; the same argument
tests/litellm-validate_test.sh makes about its own consolidation.

WHAT DIFFERS, AND WHY

- Diff: three commands, run all of them. Which one holds the change is itself
  information — work that is neither staged nor committed is a working tree, not a
  diff under review. Untracked files appear in neither diff, so `git status
  --porcelain` is how a control that exists only in an unstaged file gets noticed.
- CI: it CANNOT have run, nothing is pushed. So "CI absent" must not block here —
  that rule is for a pushed branch with no runs, which is a platform failure;
  unpushed with no runs is arithmetic. Instead run the local gate and check its
  EXIT CODE, because a grep over gate output has hidden a failing test in this
  estate before.
- Verdict: nothing to merge, no PR to close, no branch to delete. The entire output
  is a comment on the issue. That is what makes the lane RECORDED rather than a
  conversation — a verdict living only in a chat transcript is indistinguishable
  from no review having happened.

The report must state that it carries strictly less external evidence than PR mode:
"nothing I could find blocks this push", never "CI confirms this".

TDD, and one vacuous assertion caught

Five assertions written first, all red. One passed spuriously — an unscoped grep
for "do not merge" matched line 202, the ESCALATION step talking about a PR. A pass
for entirely the wrong reason, which is what rule 9 is about. Now scoped to the
pre-push section, and the comment records why, so nobody re-loosens it.

agents_test 19/19. Repo check exit 0, 45 skills, manifest matches tag.

Refs mathias/infra#470

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/agents_test.sh

@@ -103,6 +103,62 @@ else
   ok 'doctor is silent when no host-local copy exists'
 fi
 
+# --- the pre-push mode the GitOps review lane depends on (infra#470) ---------
+#
+# infra#470 resolved a doctrine conflict: root rule 5 wants a PR for risk/medium+,
+# and mathias/infra forbids branches because Flux watches main and a branch can be
+# linted but never reconciled. The agreed lane is that such work stays on main and
+# instead gets a RECORDED ADVERSARIAL REVIEW PASS before the push.
+#
+# That lane names this agent as its reviewer. If the definition only knows how to
+# review an open PR, the lane resolves to "be careful" — which is what rule 5 was
+# written to replace. These assertions observe FILE CONTENT only: that the mode is
+# documented, that it does not merge, and that the verdict has a stated home. They
+# do NOT claim the agent reviews a staged diff well (rule 9).
+
+if grep -qi 'git diff --staged\|git diff --cached' "$AGENT"; then
+  ok 'the definition names a command that reads a staged diff, not only a branch diff'
+else
+  no 'the definition has no staged-diff command, so the infra#470 lane has no reviewer'
+fi
+
+if grep -qi 'pre-push' "$AGENT"; then
+  ok 'the definition names the pre-push mode'
+else
+  no 'the definition does not name a pre-push mode (infra#470)'
+fi
+
+# The verdict has to land somewhere durable, or "recorded review pass" is untrue.
+# The lane specifies the issue, deliberately not a PR thread — there is no PR.
+if grep -qi 'verdict in the issue\|verdict goes in the issue' "$AGENT"; then
+  ok 'the definition states the verdict goes in the issue'
+else
+  no 'the definition does not say where a pre-push verdict is recorded'
+fi
+
+# In pre-push mode there is nothing to merge and no PR to close. An agent that
+# reaches for pr_merge there would be acting on a PR that does not exist.
+#
+# SCOPED to the pre-push section on purpose. An unscoped grep for "do not merge"
+# passes on line 202 of the current file, which is the ESCALATION step talking
+# about a PR — a pass for entirely the wrong reason, and the kind of vacuous
+# assertion rule 9 is about. Caught by checking what the green was matching.
+PREPUSH=$(awk '/[Pp]re-push/{f=1} f&&/^## [^#]/&&!/[Pp]re-push/{f=0} f' "$AGENT")
+if printf '%s' "$PREPUSH" | grep -qi 'nothing to merge\|do not merge\|no PR to merge'; then
+  ok 'the pre-push section itself rules out merging'
+else
+  no 'the pre-push section does not rule out merging (an unscoped grep would pass here wrongly)'
+fi
+
+# CI cannot have run on an unpushed diff, so the CI step's meaning changes. A
+# definition that still treats "CI green" as available would grade on a signal
+# that does not exist yet.
+if grep -qi 'CI has not run\|no CI run yet\|CI cannot have run' "$AGENT"; then
+  ok 'the definition acknowledges CI has not run on an unpushed diff'
+else
+  no 'the definition does not address CI being absent pre-push'
+fi
+
 rm -rf "$WORK"
 printf '\n%s passed, %s failed\n' "$pass" "$fail"
 [ "$fail" -eq 0 ]