diff --git a/api/tests/test_secret_guard.py b/api/tests/test_secret_guard.py
index 8009f64..e1fbf2e 100644
--- a/api/tests/test_secret_guard.py
+++ b/api/tests/test_secret_guard.py
@@ -104,3 +104,16 @@ def test_block_and_warn(monkeypatch):
     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")
+
+
+def test_public_scan_excuses_by_hash_and_by_path():
+    spec = importlib.util.spec_from_file_location("public_secret_scan", ROOT / "scripts" / "public_secret_scan.py")
+    ps = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(ps)
+    allow = {"windy-agent": {"hashes": {"aaaa1111"}, "paths": [("tests/keys/*", {"private key block"})]}}
+    assert ps.excused("windy-agent", "openai key", "aaaa1111", ["tests/x.py"], allow)
+    assert not ps.excused("windy-agent", "telegram bot token", "1354fc9b", ["tests/test_log_redaction.py"], allow)
+    assert ps.excused("windy-agent", "private key block", "ffff0000", ["tests/keys/a.pem"], allow)
+    # a PEM header anywhere outside the allowed paths still counts
+    assert not ps.excused("windy-agent", "private key block", "ffff0000", ["tests/keys/a.pem", "deploy/k.pem"], allow)
+    assert not ps.excused("other", "openai key", "aaaa1111", ["x"], allow)
diff --git a/ci/secret-guard-allow.yml b/ci/secret-guard-allow.yml
index 99ec5df..dd3b99a 100644
--- a/ci/secret-guard-allow.yml
+++ b/ci/secret-guard-allow.yml
@@ -44,3 +44,7 @@ allow:
     paths: ["tools/conformance/test-keys/*"]
     kinds: [private key block]
     reason: "Conformance-suite test keys (named test-private.pem)."
+  - repo: windy-git
+    paths: ["api/tests/test_secret_guard.py"]
+    kinds: [private key block]
+    reason: "The guard's own test uses a PEM header string as a sample."
diff --git a/scripts/public_secret_scan.py b/scripts/public_secret_scan.py
new file mode 100644
index 0000000..fe25337
--- /dev/null
+++ b/scripts/public_secret_scan.py
@@ -0,0 +1,118 @@
+#!/usr/bin/env python3
+"""Weekly: every PUBLIC repo in Grant's GitHub accounts, full history (every object,
+reachable or not, incl. PR refs), for secret-shaped strings. Leak hunt 09-24: a
+real bot token sat in a public test fixture for five months.
+
+Output is hash + location only, never a value (house rule 10). Known fakes are
+excused by ci/secret-guard-allow.yml (same file as secret-guard; the repo NAME is
+matched across accounts). Runs on Veron as user1-gpu (gh is logged in there):
+
+  python3 scripts/public_secret_scan.py [--out FILE] [--owners a,b,...]
+"""
+
+from __future__ import annotations
+
+import argparse
+import fnmatch
+import json
+import subprocess
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+import secret_shapes as ss  # noqa: E402
+
+OWNERS = ["sneakyfree", "VERONTECH", "Windstorm-Institute", "Windstorm-Labs", "Public-Streamer"]
+WORK = Path.home() / "leakscan" / "public"
+MAX_BLOB = 20_000_000
+
+
+def _run(*a: str) -> subprocess.CompletedProcess:
+    return subprocess.run(a, capture_output=True)
+
+
+def blob_hits(bare: Path) -> dict[str, list[tuple[str, str]]]:
+    """{blob: [(kind, hash8)]} over every blob object in the repo."""
+    chk = _run("git", "-C", str(bare), "cat-file", "--batch-all-objects",
+               "--batch-check=%(objectname) %(objecttype) %(objectsize)")
+    blobs = [p[0] for p in (ln.split() for ln in chk.stdout.decode().splitlines())
+             if len(p) == 3 and p[1] == "blob" and int(p[2]) < MAX_BLOB]
+    if not blobs:
+        return {}
+    import threading
+    p = subprocess.Popen(["git", "-C", str(bare), "cat-file", "--batch"], stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+
+    def feed() -> None:  # separate thread: writing everything first deadlocks (both pipes fill)
+        p.stdin.write(("\n".join(blobs) + "\n").encode())
+        p.stdin.close()
+    threading.Thread(target=feed, daemon=True).start()
+    out: dict[str, list[tuple[str, str]]] = {}
+    for _ in blobs:
+        hdr = p.stdout.readline().split()
+        data = p.stdout.read(int(hdr[2]))
+        p.stdout.read(1)
+        found = ss.find(data.decode("utf-8", "ignore"))
+        if found:
+            out[hdr[0].decode()] = found
+    p.wait()
+    return out
+
+
+def locate(bare: Path, blob: str) -> dict:
+    lg = _run("git", "-C", str(bare), "log", "--all", "--format=@@%H %cI", "--name-only",
+              f"--find-object={blob}").stdout.decode()
+    commits, paths = [], set()
+    for line in lg.splitlines():
+        if line.startswith("@@"):
+            commits.append(line[2:].split())
+        elif line.strip():
+            paths.add(line.strip())
+    head = _run("git", "-C", str(bare), "ls-tree", "-r", "HEAD").stdout.decode()
+    first = commits[-1] if commits else ["unreachable", "-"]
+    return {"paths": sorted(paths), "first_commit": first[0][:10], "first_date": first[1],
+            "in_head": blob in head}
+
+
+def excused(repo: str, kind: str, h: str, paths: list[str], allow: dict) -> bool:
+    a = allow.get(repo) or {"hashes": set(), "paths": []}
+    if kind in {"private key block"}:
+        return bool(paths) and all(any(kind in k and fnmatch.fnmatch(p, g) for g, k in a["paths"]) for p in paths)
+    return h in a["hashes"]
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--out", default=str(WORK / "latest.json"))
+    ap.add_argument("--owners", default=",".join(OWNERS))
+    args = ap.parse_args()
+    import secret_guard as sg
+    allow = sg.load_allow()
+    WORK.mkdir(parents=True, exist_ok=True)
+    rows, scanned, errors = [], [], []
+    for owner in args.owners.split(","):
+        lst = _run("gh", "repo", "list", owner, "--limit", "1000", "--visibility", "public", "--json", "name")
+        for r in json.loads(lst.stdout or b"[]"):
+            name = r["name"]
+            bare = WORK / owner / f"{name}.git"
+            if bare.exists():
+                c = _run("git", "-C", str(bare), "remote", "update", "--prune")
+            else:
+                bare.parent.mkdir(parents=True, exist_ok=True)
+                c = _run("gh", "repo", "clone", f"{owner}/{name}", str(bare), "--", "--mirror", "-q")
+            if c.returncode:
+                errors.append(f"{owner}/{name}")
+                continue
+            scanned.append(f"{owner}/{name}")
+            for blob, found in blob_hits(bare).items():
+                loc = locate(bare, blob)
+                for kind, h in sorted(set(found)):
+                    rows.append({"repo": f"{owner}/{name}", "kind": kind, "hash8": h, **loc,
+                                 "excused": excused(name, kind, h, loc["paths"], allow)})
+    Path(args.out).write_text(json.dumps({"scanned": scanned, "errors": errors, "rows": rows}, indent=1))
+    new = [r for r in rows if not r["excused"]]
+    print(f"scanned {len(scanned)} public repos, {len(errors)} errors, {len(rows)} secret-shaped, {len(new)} NOT excused")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())