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>

scripts/secret_shapes.py

@@ -0,0 +1,40 @@
+"""Secret-shaped strings, shared by secret_guard (bridged repos) and
+public_secret_scan (weekly, every public repo). A finding NEVER carries the value:
+only its kind and sha256[:8] (house rule 10). Leak hunt 09-24: @Windy_0_bot's
+token sat in a public repo's test fixture for five months."""
+
+from __future__ import annotations
+
+import hashlib
+import re
+
+# (kind, regex). Order matters only for readability; each match is reported once.
+PATTERNS: list[tuple[str, re.Pattern[str]]] = [
+    ("telegram bot token", re.compile(r"(?<![0-9])[0-9]{8,10}:[A-Za-z0-9_-]{35}(?![A-Za-z0-9_-])")),
+    ("github token", re.compile(r"\b(?:gh[pousr]_[A-Za-z0-9]{36}|github_pat_[A-Za-z0-9_]{82})\b")),
+    ("aws access key", re.compile(r"\b(?:AKIA|ASIA)[0-9A-Z]{16}\b")),
+    ("slack token", re.compile(r"\bxox[abprs]-[A-Za-z0-9-]{10,}")),
+    ("anthropic key", re.compile(r"\bsk-ant-[A-Za-z0-9_-]{20,}")),
+    ("openai key", re.compile(r"\bsk-(?:proj-|svcacct-)?(?!ant-)[A-Za-z0-9_-]{32,}")),
+    ("stripe live key", re.compile(r"\b[rs]k_live_[A-Za-z0-9]{20,}")),
+    ("google api key", re.compile(r"\bAIza[0-9A-Za-z_-]{35}(?![0-9A-Za-z_-])")),
+    ("private key block", re.compile(r"-----BEGIN (?:RSA |EC |DSA |OPENSSH |ENCRYPTED )?PRIVATE KEY-----")),
+]
+
+# git grep -E (POSIX ERE) prefilter: cheap superset of PATTERNS.
+PREFILTER = ("[0-9]{8,10}:[A-Za-z0-9_-]{35}|gh[pousr]_[A-Za-z0-9]{36}|github_pat_|(AKIA|ASIA)[0-9A-Z]{16}"
+             "|xox[abprs]-|sk-ant-|sk-[A-Za-z0-9_-]{32}|sk-proj-|[rs]k_live_|AIza[0-9A-Za-z_-]{35}"
+             "|-----BEGIN [A-Z ]*PRIVATE KEY-----")
+
+
+def h8(value: str | bytes) -> str:
+    return hashlib.sha256(value.encode() if isinstance(value, str) else value).hexdigest()[:8]
+
+
+def find(text: str) -> list[tuple[str, str]]:
+    """[(kind, hash8)] for every secret-shaped string in `text`. Values never leave."""
+    out = []
+    for kind, rx in PATTERNS:
+        for m in rx.finditer(text):
+            out.append((kind, h8(m.group(0))))
+    return out