fix: add _stored_to_legacy helper, load_auth compat, and old-format roundtrip test

docs/current_roadmap.md

@@ -102,9 +102,10 @@ auth admin are implemented. The next work is polish, not new broad surfaces.
 - Completed: server startup policy moved to `wf_server.cli`; JSON-RPC HTTP
   remains in `wf_transport_rpc_http`:
   [`server CLI and transport boundary`](superpowers/specs/2026-06-10-server-cli-transport-boundary.md).
-- Next auth work: typed/discriminated auth records, source-owned auth binders
-  (`McpAuthBinder` first), OAuth refresh-token support, and Google Drive MCP smoke
-  through `https://drivemcp.googleapis.com/mcp/v1`. Production secret manager
+- Next auth work: typed/discriminated auth records and source-owned auth binders
+  (`McpAuthBinder` first) are now completed. Remaining: OAuth refresh-token
+  support and Google Drive MCP smoke through
+  `https://drivemcp.googleapis.com/mcp/v1`. Production secret manager
   integration and encrypted-at-rest file format remain deferred.
 - Active specs:
   - [`workflow config targets and sources`](superpowers/specs/2026-06-03-workflow-config-targets-and-sources.md)

docs/superpowers/specs/2026-06-06-auth-source-secrets-boundary.md

@@ -19,7 +19,8 @@ diagnostics and source registry apply summaries. Slice 3 exposes read-only auth
 admin summaries without secret payload values. Slice 4 adds local/dev file-backed
 auth save/delete through neutral admin, JSON-RPC, and CLI. Responses still
 expose only ids, schemes, metadata, and payload keys; secret payload values
-remain write-only.
+remain write-only. Slice 5 introduces typed stored auth records and MCP auth
+binding while preserving old `scheme + payload` compatibility input.
 
 Next auth work should replace the stringly `scheme + payload` record with typed
 auth variants and source-owned auth binders. Google Drive's remote HTTP MCP

src/wf_sources_mcp/storage/store.py

@@ -11,13 +11,41 @@ from pathlib import Path
 from typing import TYPE_CHECKING
 
 from wf_api.auth import AuthRecord as NeutralAuthRecord
-from wf_api.auth import StoredAuthRecord, validate_auth_id
+from wf_api.auth import (
+    BearerAuth,
+    EnvAuth,
+    HeaderAuth,
+    OAuthRefreshTokenAuth,
+    OpaqueAuth,
+    StoredAuthRecord,
+    validate_auth_id,
+)
 from wf_sources_mcp.auth import AuthRecord, mcp_auth_from_neutral, neutral_auth_from_mcp
 
 if TYPE_CHECKING:
     from wf_sources_mcp.catalog.models import CatalogSnapshot
 
 
+def _stored_to_legacy(record: StoredAuthRecord) -> AuthRecord:
+    """Convert a typed StoredAuthRecord back to legacy AuthRecord for compat."""
+    auth = record.auth
+    if isinstance(auth, BearerAuth):
+        return AuthRecord(record.id, "bearer", {"token": auth.access_token})
+    if isinstance(auth, HeaderAuth):
+        return AuthRecord(record.id, "headers", {"headers": dict(auth.headers)})
+    if isinstance(auth, EnvAuth):
+        return AuthRecord(record.id, "env", {"env": dict(auth.env)})
+    if isinstance(auth, OAuthRefreshTokenAuth):
+        return AuthRecord(
+            record.id,
+            "oauth_refresh_token",
+            auth.model_dump(mode="json", exclude={"kind"}),
+        )
+    if isinstance(auth, OpaqueAuth):
+        return AuthRecord(record.id, auth.scheme, dict(auth.payload))
+    raise TypeError(f"unsupported auth variant {type(auth).__name__}")
+
+
 class AuthStore:
     def save_auth(self, record: AuthRecord) -> None:
         raise NotImplementedError
@@ -95,6 +123,8 @@ class FileAuthStore(AuthStore):
         if not path.exists():
             return None
         data = json.loads(path.read_text(encoding="utf-8"))
+        if "kind" in data.get("auth", {}):
+            return _stored_to_legacy(StoredAuthRecord.model_validate(data))
         return AuthRecord(**data)
 
     def list_auth_refs(self) -> list[str]:

tests/wf_sources_mcp/test_auth_storage_exports.py

@@ -127,3 +127,47 @@ def test_file_auth_store_writes_new_stored_auth_record_shape(tmp_path: Path) ->
     assert data["auth"]["kind"] == "bearer"
     assert data["auth"]["access_token"] == "token"
     assert data["metadata"]["provider"] == "google"
+
+
+def test_file_auth_store_loads_old_format_through_load_auth_record(tmp_path: Path) -> None:
+    store = FileAuthStore(tmp_path)
+    path = tmp_path / "auth" / "github.work.json"
+    path.write_text(
+        json.dumps(
+            {
+                "connection_id": "github.work",
+                "scheme": "bearer",
+                "payload": {"token": "secret"},
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    record = store.load_auth_record("github.work")
+
+    assert isinstance(record, NeutralAuthRecord)
+    assert record.id == "github.work"
+    assert record.scheme == "bearer"
+    assert record.payload["token"] == "secret"
+
+
+def test_file_auth_store_loads_new_format_through_load_auth(tmp_path: Path) -> None:
+    store = FileAuthStore(tmp_path)
+    path = tmp_path / "auth" / "google.drive.personal.json"
+    path.write_text(
+        json.dumps(
+            {
+                "id": "google.drive.personal",
+                "auth": {"kind": "bearer", "access_token": "token"},
+                "metadata": {"provider": "google"},
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    legacy = store.load_auth("google.drive.personal")
+
+    assert legacy is not None
+    assert legacy.connection_id == "google.drive.personal"
+    assert legacy.scheme == "bearer"
+    assert legacy.payload["token"] == "token"