fix(agent-team): post-build denied-path check writes scratch outside the checkout (#38)

Live smoke exposed a self-pollution bug (pre-existing from PR #17): the post-build
denied-path check wrote its own _build_diff_z.bin / _build_status_z.bin into the
working tree, then its own `git status --untracked-files=all` flagged them as
out-of-scope writes — failing any run with a narrow declared_scope (the smoke's
docs/**). Write them to $RUNNER_TEMP instead (read via $_DIFF_Z/$_STATUS_Z), so
the check no longer sees its own temp files. The agent-team pytest artifacts were
already correctly gitignored; only the check's own files tripped it. Test harness
updated to pass the env paths. 1044 tests, ruff clean.

.github/workflows/agent-team-apply-verify.yml

@@ -742,8 +742,15 @@ jobs:
           # mangling is done anywhere. A path that cannot be cleanly decoded is
           # treated as a VIOLATION (fail closed).
           git config core.quotepath false
-          git diff -z --name-only HEAD > ./_build_diff_z.bin || true
-          git status --porcelain=v1 -z --untracked-files=all > ./_build_status_z.bin || true
+          # Write the scratch capture files OUTSIDE the checkout ($RUNNER_TEMP) so
+          # the `git status --untracked-files=all` below does not see — and flag —
+          # the check's OWN temp files as out-of-scope writes (they would otherwise
+          # appear as untracked and fail a narrow declared_scope).
+          _DIFF_Z="${RUNNER_TEMP:-/tmp}/_build_diff_z.bin"
+          _STATUS_Z="${RUNNER_TEMP:-/tmp}/_build_status_z.bin"
+          export _DIFF_Z _STATUS_Z
+          git diff -z --name-only HEAD > "$_DIFF_Z" || true
+          git status --porcelain=v1 -z --untracked-files=all > "$_STATUS_Z" || true
           python3 - <<'PY'
           from __future__ import annotations
 
@@ -885,7 +892,7 @@ jobs:
               """`git diff -z --name-only` records: each NUL field is one path."""
               ok: list[str] = []
               bad: list[bytes] = []
-              for rec in _read_z("./_build_diff_z.bin"):
+              for rec in _read_z(os.environ["_DIFF_Z"]):
                   dec = _decode(rec)
                   (ok if dec is not None else bad).append(dec if dec is not None else rec)
               return ok, bad
@@ -901,7 +908,7 @@ jobs:
               """
               ok: list[str] = []
               bad: list[bytes] = []
-              recs = _read_z("./_build_status_z.bin")
+              recs = _read_z(os.environ["_STATUS_Z"])
               i = 0
               while i < len(recs):
                   rec = recs[i]

agent-team/tests/test_apply_verify_workflow_hardening.py

@@ -390,9 +390,18 @@ def _run_post_build(
 
     script = tmp_path / "post_build.py"
     script.write_text(_extract_post_build_script(), encoding="utf-8")
-    (tmp_path / "_build_diff_z.bin").write_bytes(diff_z)
-    (tmp_path / "_build_status_z.bin").write_bytes(status_z)
-    env = dict(os.environ, DECLARED_SCOPE=scope)
+    diff_z_path = tmp_path / "_build_diff_z.bin"
+    status_z_path = tmp_path / "_build_status_z.bin"
+    diff_z_path.write_bytes(diff_z)
+    status_z_path.write_bytes(status_z)
+    # The script now reads its capture files from $_DIFF_Z / $_STATUS_Z (written
+    # outside the checkout in CI so the check's own temp files are not flagged).
+    env = dict(
+        os.environ,
+        DECLARED_SCOPE=scope,
+        _DIFF_Z=str(diff_z_path),
+        _STATUS_Z=str(status_z_path),
+    )
     result = subprocess.run(
         [sys.executable, str(script)],
         env=env,