secret-guard: no live credentials in bridged repos (hash-only findings)

New guard windy-git/secret-guard (warn-only) over EVERY text file: Telegram,
GitHub, AWS, Slack, Anthropic, OpenAI, Stripe live, Google API keys and
private-key blocks (scripts/secret_shapes.py, shared with the weekly public
scan). A finding carries "<kind> #<sha256[:8]>", never the value (house rule
10). Known fakes allowed BY HASH (ci/secret-guard-allow.yml). GUARDS_STATUS
gets a secrets column. Leak hunt 09-24: @Windy_0_bot token in a public fixture.

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

api/tests/test_secret_guard.py

@@ -0,0 +1,84 @@
+"""Secret guard: shapes, hash-only findings, allow by hash."""
+
+from __future__ import annotations
+
+import importlib.util
+import sys
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[2]
+sys.path.insert(0, str(ROOT / "scripts"))
+_spec = importlib.util.spec_from_file_location("secret_guard", ROOT / "scripts" / "secret_guard.py")
+sg = importlib.util.module_from_spec(_spec)
+sys.modules["secret_guard"] = sg
+_spec.loader.exec_module(sg)
+ss = sg.ss
+
+# Synthetic shapes only: none of these is a real credential.
+TG = "1234567890:" + "A" * 35
+CASES = [
+    ("telegram bot token", f"TELEGRAM_BOT_TOKEN={TG}"),
+    ("github token", "token = 'ghp_" + "a1" * 18 + "'"),
+    ("aws access key", "aws_access_key_id = AKIA" + "ABCDEFGHIJKLMNOP"),
+    ("slack token", "xoxb-" + "1234567890-abcdefghij"),
+    ("anthropic key", "ANTHROPIC_API_KEY=sk-ant-" + "x" * 30),
+    ("openai key", "OPENAI_API_KEY=sk-proj-" + "y" * 40),
+    ("stripe live key", "STRIPE=sk_live_" + "z" * 24),
+    ("google api key", "key=AIza" + "B" * 35),
+    ("private key block", "-----BEGIN OPENSSH PRIVATE KEY-----"),
+]
+
+
+@pytest.mark.parametrize("kind, text", CASES)
+def test_each_shape_is_found_and_only_its_hash_is_kept(kind, text):
+    hits = sg.scan_line("app.py", text)
+    assert [k for k, _ in hits] == [kind]
+    match = hits[0][1]
+    assert match.startswith(f"{kind} #") and len(match.rsplit("#", 1)[1]) == 8
+    # house rule 10: the value itself must never appear in a finding
+    secret = text.split("=", 1)[-1].strip(" '")
+    assert secret not in match
+
+
+@pytest.mark.parametrize("text", [
+    "sha512-" + "Q" * 86 + "==",           # lockfile integrity
+    "version: 12345678:abc",               # short, not a token
+    "sk-ant-short",                        # too short
+    "re_test_register_sends_verification", # windy-pro's fake Resend key
+    "ANTHROPIC_API_KEY=",                  # a name, not a value
+])
+def test_non_secrets_are_not_flagged(text):
+    assert sg.scan_line("x", text) == []
+
+
+def test_anthropic_key_is_not_double_counted_as_openai():
+    assert [k for k, _ in sg.scan_line("x", "sk-ant-" + "q" * 40)] == ["anthropic key"]
+
+
+def test_allow_is_by_hash_only():
+    F = sg.cg.Finding
+    fake = F("tests/t.py", 3, "telegram bot token", f"telegram bot token #{ss.h8(TG)}")
+    real = F("tests/t.py", 9, "telegram bot token", "telegram bot token #deadbeef")
+    kept = sg._drop_allowed("windy-chat", [fake, real], {"windy-chat": {ss.h8(TG)}})
+    assert kept == [real]
+    assert sg._drop_allowed("windy-mail", [fake], {"windy-chat": {ss.h8(TG)}}) == [fake]
+
+
+def test_allow_file_loads_and_needs_reasons(tmp_path):
+    assert sg.load_allow() == {} or isinstance(sg.load_allow(), dict)
+    bad = tmp_path / "a.yml"
+    bad.write_text("allow:\n  - repo: r\n    hashes: [abcd1234]\n")
+    with pytest.raises(ValueError):
+        sg.load_allow(bad)
+
+
+def test_block_and_warn(monkeypatch):
+    f = sg.cg.Finding("a.py", 1, "github token", "github token #abcd1234")
+    monkeypatch.setattr(sg, "MODE", "block")
+    assert sg.status_for([f], False)[0] == "failure"
+    assert sg.status_for([], False, grant=[f])[0] == "success"
+    monkeypatch.setattr(sg, "MODE", "warn")
+    state, desc, _ = sg.status_for([f], True)
+    assert state == "success" and desc.startswith("⚠ WARN (not blocking): 1 secret-shaped string in tree")