Gate nested projects in bash-guard instead of passing them ungated

The build-and-test gate searched for marker files only two levels below the
repo root. This repo keeps its python projects at
plugins/<name>/skills/<skill>/, four levels down, so every push reported "no
recognized project layout" and pushed without running a single test. A gate
that announces it did nothing is worse than no gate, because the announcement
scrolls past and the push still succeeds.

Walk to depth 4, and resolve python tooling properly. A bare `ruff` or
`pytest` is usually absent from PATH, and run() treats ENOENT as a pass, so an
unresolved tool would have skipped the check just as silently. Resolution now
tries the project's own .venv, then uv (which needs a [project] table that
audit-terraform does not have), then the interpreter's -m form.

A tool that is genuinely not installed is reported as an advisory note rather
than blocking. Its absence is a gap in coverage, not a defect in the change
being pushed. Silence is the one outcome that is never acceptable.

Verified by injecting a failing test into each skill and confirming the guard
blocks: audit-code resolves through its .venv, audit-terraform through
python -m pytest. The new regression tests fail against the old depth-2 walk
and pass against this one.

Tests: 8 passing (bash-guard), 197 (audit-code), 106 (audit-terraform).

plugins/guards/hooks/test-bash-guard.py

@@ -12,15 +12,16 @@ import os
 import socket
 import subprocess
 import sys
+import tempfile
 
 GUARD = os.path.join(os.path.dirname(os.path.abspath(__file__)), "bash-guard.mjs")
 
 
-def run_guard(payload):
+def run_guard(payload, cwd=None):
     """Invoke the guard with fd 0 as a socket. Returns its parsed stdout, or None if silent."""
     parent, child = socket.socketpair()
     proc = subprocess.Popen(
-        ["node", GUARD], stdin=child.fileno(), stdout=subprocess.PIPE, close_fds=False
+        ["node", GUARD], stdin=child.fileno(), stdout=subprocess.PIPE, close_fds=False, cwd=cwd
     )
     child.close()
     parent.sendall(json.dumps(payload).encode())
@@ -68,4 +69,31 @@ check("unrelated command is allowed", decision(r) != "deny", f"got {decision(r)!
 r = run_guard(bash('git commit -m "x\n\nCo-Authored-By: Claude <[email protected]>"'))
 check("Claude attribution is denied", decision(r) == "deny", f"got {decision(r)!r}")
 
+
+def nested_repo(tmp, test_body):
+    skill = os.path.join(tmp, "plugins", "reviews", "skills", "audit-x")
+    os.makedirs(os.path.join(skill, "tests"))
+    subprocess.run(["git", "init", "-q", tmp], check=True)
+    open(os.path.join(skill, "pyproject.toml"), "w").write("[tool.pytest.ini_options]\n")
+    open(os.path.join(skill, "tests", "test_nested.py"), "w").write(test_body)
+    return skill
+
+
+print("\nnested project detection (depth 4):")
+
+with tempfile.TemporaryDirectory() as tmp:
+    nested_repo(tmp, "def test_fails():\n    assert False\n")
+    r = run_guard(bash("jj git push --bookmark main"), cwd=tmp)
+    check("failing nested test blocks the push", decision(r) == "deny", f"got {decision(r)!r}")
+    check(
+        "denial names the nested project path",
+        "plugins/reviews/skills/audit-x" in reason(r),
+        f"got {reason(r)!r}",
+    )
+
+with tempfile.TemporaryDirectory() as tmp:
+    nested_repo(tmp, "def test_passes():\n    assert True\n")
+    r = run_guard(bash("jj git push --bookmark main"), cwd=tmp)
+    check("passing nested test allows the push", decision(r) != "deny", f"got {decision(r)!r}")
+
 sys.exit(1 if failures else 0)