fix: redact identity secrets through a public hook and mask issued agm_ tokens

Identity gains a redact field that the executor honours, so the OAuth
resolver no longer needs an executor subclass overriding private
internals. Opaque agm_ tokens issued by our authorization server are now
masked by the secret patterns wherever they appear in content.

src/aegis_gitea_mcp/oauth/resolver.py

@@ -18,7 +18,6 @@ import dataclasses
 import logging
 import time
 from collections.abc import Callable
-from dataclasses import dataclass, field
 from typing import TYPE_CHECKING
 
 from mcp.server.auth.provider import AccessToken
@@ -26,14 +25,12 @@ from mcp.server.auth.provider import AccessToken
 from aegis_gitea_mcp.audit import AuditLogger, get_audit_logger
 from aegis_gitea_mcp.auth import STATIC_CLIENT_ID, IdentityResolver
 from aegis_gitea_mcp.errors import ToolError
-from aegis_gitea_mcp.gitea import GiteaExecutor
-from aegis_gitea_mcp.gitea.redaction import normalize_secrets
 from aegis_gitea_mcp.identity import Identity
 from aegis_gitea_mcp.oauth.store import OAuthStore, OAuthStoreError, SessionRecord
 from aegis_gitea_mcp.oauth.upstream import GiteaUpstream, UpstreamError, UpstreamInvalidGrant
 
 if TYPE_CHECKING:
-    from aegis_gitea_mcp.gitea.executor import _Call
+    pass
 
 logger = logging.getLogger(__name__)
 
@@ -47,26 +44,6 @@ OAUTH_ONLY = (
 )
 
 
-@dataclass(frozen=True)
-class SessionIdentity(Identity):
-    """An OAuth identity that also names session secrets to redact from results.
-
-    Attributes:
-        redact: Further secrets of the session (the Gitea refresh token) that must
-            never appear in a result. Excluded from ``repr`` and comparisons.
-    """
-
-    redact: tuple[str, ...] = field(default=(), repr=False, compare=False)
-
-
-class OAuthGiteaExecutor(GiteaExecutor):
-    """Executor that also redacts the session secrets carried by a :class:`SessionIdentity`."""
-
-    def _secrets(self, identity: Identity, call: _Call) -> tuple[str, ...]:
-        extra = identity.redact if isinstance(identity, SessionIdentity) else ()
-        return normalize_secrets([*super()._secrets(identity, call), *extra])
-
-
 class OAuthIdentityResolver:
     """Maps a verified access token to the identity a tool call runs as.
 
@@ -120,7 +97,8 @@ class OAuthIdentityResolver:
         if self._needs_refresh(session):
             session = await self._refresh(session_id)
         redact = (session.gitea_refresh_token,) if session.gitea_refresh_token else ()
-        return SessionIdentity(
+        # The executor redacts ``Identity.redact`` (the Gitea refresh token) from results.
+        return Identity(
             login=session.login, mode="oauth", token=session.gitea_access_token, redact=redact
         )