compute guard: line-scoped allow entries; allow MindKeychain.jsx's two OAuth endpoints only

Allow entries may carry matches: (regexes); then only matching lines are
allowed, so an allowed file can't smuggle in a new call. windy-pro #609
MindKeychain.jsx: openrouter.ai/auth? and /api/v1/auth/keys (BYOK key
acquisition via OAuth PKCE, no inference; successor of the MindPanel
allow, ADR-064). An inference call in the same file still flags (tested).
Orchestrator-approved.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/tests/test_compute_guard.py

@@ -191,3 +191,32 @@ def test_a_commit_not_fetched_yet_is_skipped_not_an_error(tmp_path, monkeypatch)
     (tmp_path / "windy-chat.git").symlink_to(bare)
     assert cg.check("windy-chat", "f" * 40, "main", True) is None     # pushed after the fetch
     assert [f.kind for f in cg.check("windy-chat", sha, "main", True)] == ["provider SDK"]
+
+
+KEYCHAIN = "src/client/web/src/pages/panels/MindKeychain.jsx"
+
+
+def test_scoped_allow_admits_only_the_oauth_endpoints():
+    ok = [
+        "    window.location.href = `https://openrouter.ai/auth?callback_url=${encodeURIComponent(callback)}`",
+        "    const res = await fetch('https://openrouter.ai/api/v1/auth/keys', {",
+    ]
+    for line in ok:
+        assert cg.allowed("windy-pro", KEYCHAIN, ALLOW, line)
+    # an inference call smuggled into the same file still flags
+    assert not cg.allowed("windy-pro", KEYCHAIN, ALLOW,
+                          "  await fetch('https://openrouter.ai/api/v1/chat/completions', {")
+    # a scoped entry never allows a line it can't see
+    assert not cg.allowed("windy-pro", KEYCHAIN, ALLOW)
+
+
+def test_scoped_allow_in_a_real_diff():
+    diff = f"""--- /dev/null
++++ b/{KEYCHAIN}
+@@ -0,0 +1,3 @@
++  window.location.href = `https://openrouter.ai/auth?callback_url=x`
++  const res = await fetch('https://openrouter.ai/api/v1/auth/keys', {{
++  await fetch('https://openrouter.ai/api/v1/chat/completions', {{
+"""
+    fs = cg.parse_added("windy-pro", diff, ALLOW)
+    assert [(f.line, f.match) for f in fs] == [(3, "openrouter.ai")]

ci/compute-guard-allow.yml

@@ -35,6 +35,13 @@ allow:
     paths: ["src/client/web/src/pages/panels/MindPanel.jsx"]
     reason: "Validates the USER's own OpenRouter key for BYOK (audit #10); spends no house money."
 
+  - repo: windy-pro
+    paths: ["src/client/web/src/pages/panels/MindKeychain.jsx"]
+    # ONLY these two endpoints: any other openrouter.ai call in this file (e.g.
+    # /api/v1/chat, i.e. inference) still flags. Orchestrator-approved 09-23.
+    matches: ['openrouter\.ai/auth\?', 'openrouter\.ai/api/v1/auth/keys']
+    reason: "BYOK key acquisition via OpenRouter OAuth PKCE; no inference; successor of MindPanel allow (ADR-064)."
+
   - repo: windy-git
     paths: ["scripts/compute_guard.py", "ci/compute-guard-allow.yml"]
     reason: "The guard's own pattern list and this file."

scripts/compute_guard.py

@@ -98,9 +98,18 @@ def load_allow(path: Path = ALLOW_FILE) -> list[dict]:
     return entries
 
 
-def allowed(repo: str, path: str, allow: list[dict]) -> bool:
+def allowed(repo: str, path: str, allow: list[dict], text: str | None = None) -> bool:
+    """An entry may carry `matches:` (regexes): then only lines matching one of
+    them are allowed, so an allowed file can't smuggle in a NEW call (e.g. an
+    OAuth sign-in endpoint is allowed, an inference endpoint in the same file
+    still flags). Entries without `matches` cover the whole path."""
     for e in allow:
-        if e["repo"] == repo and any(fnmatch.fnmatch(path, g) for g in e["paths"]):
+        if e["repo"] != repo or not any(fnmatch.fnmatch(path, g) for g in e["paths"]):
+            continue
+        pats = e.get("matches")
+        if not pats:
+            return True
+        if text is not None and any(re.search(rx, text) for rx in pats):
             return True
     return False
 
@@ -157,7 +166,7 @@ def scan_tree(repo: str, bare: Path, sha: str, allow: list[dict], *, line_fn=Non
             _, path, line, text = raw.split(":", 3)
         except ValueError:
             continue
-        if not path_ok(path) or allowed(repo, path, allow):
+        if not path_ok(path) or allowed(repo, path, allow, text):
             continue
         for kind, match in line_fn(path, text):
             found.append(Finding(path, int(line), kind, match))
@@ -190,7 +199,7 @@ def parse_added(repo: str, diff: str, allow: list[dict], *, line_fn=None, path_o
         if path is None or raw.startswith("--- "):
             continue
         if raw.startswith("+"):
-            if path_ok(path) and not allowed(repo, path, allow):
+            if path_ok(path) and not allowed(repo, path, allow, raw[1:]):
                 for kind, match in line_fn(path, raw[1:]):
                     found.append(Finding(path, line, kind, match))
             line += 1