fix: redact stored webhook authorization headers and other secret fields by key name (SEC-02)

src/aegis_gitea_mcp/gitea/encoding.py

@@ -96,6 +96,14 @@ _SENSITIVE_BODY_KEYS = frozenset(
 )
 _MIN_SENSITIVE_VALUE_CHARS = 4
 
+#: Response fields whose non-empty string values are replaced with ``[REDACTED]``
+#: in every result except those of credential-issuing operations (whose purpose
+#: is to return a credential). Gitea fills ``authorization_header`` on every
+#: webhook read, so a stored header would otherwise reach the model. Keep this
+#: next to :data:`_SENSITIVE_BODY_KEYS` so a new secret-bearing field is added
+#: in one place.
+SENSITIVE_RESPONSE_KEYS = _SENSITIVE_BODY_KEYS
+
 
 class ArgumentError(ValueError):
     """An argument cannot be turned into a safe request (message never echoes the value)."""

src/aegis_gitea_mcp/gitea/executor.py

@@ -13,6 +13,9 @@ Security properties (all covered by tests):
 * the identity token and ``Identity.redact``, the configured Gitea token, the MCP bearer token, the
   OAuth client secret, ``extra_secrets`` and secret values submitted in a
   request body are replaced with ``[REDACTED]`` in every result, always;
+* secret-bearing response fields (:data:`~.encoding.SENSITIVE_RESPONSE_KEYS`, for example a
+  webhook's stored ``authorization_header``) are redacted by key name in every result except
+  those of :data:`CREDENTIAL_ISSUING_OPERATIONS`, whatever ``SECRET_DETECTION_MODE`` says;
 * secret-pattern masking/blocking follows ``SECRET_DETECTION_MODE``, except for
   :data:`CREDENTIAL_ISSUING_OPERATIONS` whose purpose is to return a freshly
   minted credential (exact redaction still applies there);
@@ -38,6 +41,7 @@ from aegis_gitea_mcp.config import Settings
 from aegis_gitea_mcp.errors import kind_for_status, sanitize_message
 from aegis_gitea_mcp.gitea.encoding import (
     RAW_METHODS,
+    SENSITIVE_RESPONSE_KEYS,
     ArgumentError,
     PayloadTooLargeError,
     RequestBody,
@@ -50,7 +54,12 @@ from aegis_gitea_mcp.gitea.encoding import (
     validate_sudo,
 )
 from aegis_gitea_mcp.gitea.pagination import build_pagination
-from aegis_gitea_mcp.gitea.redaction import normalize_secrets, redact_exact, redact_text
+from aegis_gitea_mcp.gitea.redaction import (
+    normalize_secrets,
+    redact_exact,
+    redact_fields,
+    redact_text,
+)
 from aegis_gitea_mcp.identity import Identity
 from aegis_gitea_mcp.security import sanitize_data
 
@@ -613,6 +622,10 @@ class GiteaExecutor:
         """Redact, mask or block, and bound the payload size."""
         secrets = self._secrets(identity, call)
         payload = redact_exact(payload, secrets)
+        if not exempt and "data" in payload:
+            # Stored secrets (webhook authorization headers, ...) by field name: pattern
+            # masking cannot recognise them and SECRET_DETECTION_MODE may be off.
+            payload = {**payload, "data": redact_fields(payload["data"], SENSITIVE_RESPONSE_KEYS)}
         mode = self._settings.secret_detection_mode
         if mode != "off" and not exempt:
             if mode == "block":

src/aegis_gitea_mcp/gitea/redaction.py

@@ -7,7 +7,7 @@ they have, in every string of a payload (values and dict keys).
 
 from __future__ import annotations
 
-from collections.abc import Iterable
+from collections.abc import Collection, Iterable
 from typing import Any
 
 REDACTED = "[REDACTED]"
@@ -41,3 +41,36 @@ def redact_exact(value: Any, secrets: tuple[str, ...]) -> Any:
     if isinstance(value, (list, tuple)):
         return [redact_exact(item, secrets) for item in value]
     return value
+
+
+def redact_fields(value: Any, keys: Collection[str], *, max_depth: int = 128) -> Any:
+    """Replace the string values of secret-bearing fields, by key name, at any depth.
+
+    A non-empty string under a key in ``keys`` (compared lower-cased) becomes
+    ``[REDACTED]``; an empty value stays so the presence of the field is still
+    visible. Containers under such a key are searched like any other value.
+    Nesting deeper than ``max_depth`` is returned unchanged (the executor bounds
+    JSON depth before this runs).
+    """
+
+    def walk(item: Any, depth: int) -> Any:
+        if depth > max_depth:
+            return item
+        if isinstance(item, dict):
+            return {
+                key: (
+                    REDACTED
+                    if isinstance(key, str) and key.lower() in keys and _is_secret_value(sub)
+                    else walk(sub, depth + 1)
+                )
+                for key, sub in item.items()
+            }
+        if isinstance(item, (list, tuple)):
+            return [walk(sub, depth + 1) for sub in item]
+        return item
+
+    return walk(value, 0)
+
+
+def _is_secret_value(value: Any) -> bool:
+    return isinstance(value, str) and bool(value)