Refuse thin secret filenames and token shapes

src/local_coding_slm/payload.py

@@ -8,6 +8,7 @@
 
 from __future__ import annotations
 
+import re
 from collections.abc import Sequence
 
 MAX_FILES = 12
@@ -20,7 +21,20 @@
     "-----BEGIN EC PRIVATE KEY-----",
     "-----BEGIN PRIVATE KEY-----",
 )
-_TOKEN_PREFIXES = ("ghp_", "github_pat_", "sk-proj-", "sk-ant-")
+_SECRET_BASENAMES = frozenset(
+    {
+        "credentials.json",
+        "id_rsa",
+        "id_rsa.pub",
+        "id_ed25519",
+        "id_ed25519.pub",
+        "kubeconfig",
+    }
+)
+_TOKEN_RE = re.compile(r"(?<![A-Za-z0-9_])(?:ghp_|github_pat_|sk-)")
+_AWS_SECRET_ASSIGN_RE = re.compile(r"aws_secret_access_key\s*=")
+_AWS_ACCESS_KEY_ID_RE = re.compile(r"\bAKIA[0-9A-Z]*")
+_JWT_RE = re.compile(r"eyJ[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*")
 
 
 def inspect_payload(
@@ -60,23 +74,28 @@ def refusal_message(reason: str) -> str:
 
 
 def _secret_path(path: str) -> str | None:
-    name = path.replace("\\", "/").rsplit("/", 1)[-1].lower()
+    normalized = path.replace("\\", "/").lower()
+    name = normalized.rsplit("/", 1)[-1]
     if name == ".env.example":
         return None
     if name == ".env" or name.startswith(".env."):
         return "secrets_file"
-    if name in {"credentials.json", "id_rsa", "id_rsa.pub"}:
+    if name in _SECRET_BASENAMES:
+        return "secrets_file"
+    if normalized == ".aws/credentials" or normalized.endswith("/.aws/credentials"):
         return "secrets_file"
     return None
 
 
 def _secret_content(content: str) -> str | None:
     if any(marker in content for marker in _PRIVATE_KEY_MARKERS):
         return "secret_content"
-    lowered = content.lower()
-    if "aws_secret_access_key=" in lowered:
+    if _AWS_SECRET_ASSIGN_RE.search(content.lower()):
+        return "secret_content"
+    if _TOKEN_RE.search(content):
+        return "secret_content"
+    if _AWS_ACCESS_KEY_ID_RE.search(content):
+        return "secret_content"
+    if _JWT_RE.search(content):
         return "secret_content"
-    for prefix in _TOKEN_PREFIXES:
-        if prefix in content:
-            return "secret_content"
     return None

tests/test_payload.py

@@ -8,7 +8,37 @@
 from local_coding_slm.payload import MAX_FILES, inspect_payload, refusal_message
 
 
+# Leftover #6 shapes that origin/main allowed through. Fixtures only.
+_THIN_SECRET_CASES: tuple[tuple[str, list[dict[str, str]]], ...] = (
+    ("id_ed25519", [{"path": "id_ed25519", "content": "not-a-real-key"}]),
+    (".aws/credentials", [{"path": ".aws/credentials", "content": "[default]\n"}]),
+    ("kubeconfig", [{"path": "kubeconfig", "content": "apiVersion: v1\n"}]),
+    ("plain sk-", [{"path": "notes.py", "content": "sk-"}]),
+    ("AKIA", [{"path": "notes.py", "content": "AKIA"}]),
+    (
+        "JWT",
+        [
+            {
+                "path": "notes.py",
+                "content": "eyJhbGciOiJub25lIn0.eyJzdWIiOiJmaXh0dXJlIn0.e30",
+            }
+        ],
+    ),
+    (
+        "spaced aws_secret_access_key =",
+        [{"path": "notes.py", "content": "aws_secret_access_key ="}],
+    ),
+)
+
+
 class InspectPayloadTests(unittest.TestCase):
+    def test_inspect_payload_refuses_thin_secret_shapes(self) -> None:
+        for label, files in _THIN_SECRET_CASES:
+            with self.subTest(label=label):
+                reason = inspect_payload(files)
+                self.assertIsNotNone(reason, msg=label)
+                self.assertTrue(reason)
+
     def test_clean_snippet_ok(self) -> None:
         self.assertIsNone(
             inspect_payload([{"path": "add.py", "content": "def add(a, b): return a + b\n"}])