refactor(supervisor): separate MCP dispatch from transport

bot_bottle/gateway/supervisor/mcp_dispatch.py

@@ -0,0 +1,79 @@
+"""Framework-neutral MCP method and tool dispatch."""
+
+from __future__ import annotations
+
+import json
+from dataclasses import dataclass
+from typing import Callable, Protocol
+
+from bot_bottle.gateway.egress.context import resolve_client_context
+from bot_bottle.gateway.egress.schema import route_to_yaml_dict
+from bot_bottle.gateway.policy_resolver import PolicyResolver
+from bot_bottle.supervisor import types as _sv
+
+
+class Request(Protocol):
+    @property
+    def method(self) -> str: ...
+
+    @property
+    def params(self) -> dict[str, object]: ...
+
+
+class MethodNotFoundError(Exception):
+    """Raised when a JSON-RPC method has no MCP handler."""
+
+
+Handler = Callable[[dict[str, object]], object]
+
+
+@dataclass(frozen=True)
+class Handlers:
+    initialize: Handler
+    tools_list: Handler
+    list_routes: Handler
+    check_proposal: Handler
+    propose: Handler
+
+
+def dispatch(request: Request, handlers: Handlers) -> object:
+    """Route one parsed request without depending on the HTTP server."""
+    if request.method == "initialize":
+        return handlers.initialize(request.params)
+    if request.method == "notifications/initialized":
+        return None
+    if request.method == "tools/list":
+        return handlers.tools_list(request.params)
+    if request.method != "tools/call":
+        raise MethodNotFoundError(request.method)
+
+    tool = request.params.get("name")
+    if tool == _sv.TOOL_LIST_EGRESS_ROUTES:
+        return handlers.list_routes(request.params)
+    if tool == _sv.TOOL_CHECK_PROPOSAL:
+        return handlers.check_proposal(request.params)
+    return handlers.propose(request.params)
+
+
+def resolved_routes_payload(
+    resolver: PolicyResolver,
+    source_ip: str,
+    identity_token: str,
+) -> dict[str, object]:
+    """Render the calling bottle's routes, failing closed to an empty list."""
+    config, _slug, _tokens = resolve_client_context(
+        resolver, source_ip, identity_token,
+    )
+    body = json.dumps(
+        {"routes": [route_to_yaml_dict(route) for route in config.routes]},
+        indent=2,
+    )
+    return {"content": [{"type": "text", "text": body}], "isError": False}
+
+
+__all__ = [
+    "Handlers",
+    "MethodNotFoundError",
+    "dispatch",
+    "resolved_routes_payload",
+]

bot_bottle/gateway/supervisor/server.py

@@ -58,10 +58,15 @@ import typing
 from dataclasses import dataclass
 
 from bot_bottle.constants import IDENTITY_HEADER
-from bot_bottle.gateway.egress.context import resolve_client_context
+from bot_bottle.gateway.egress.schema import load_config
-from bot_bottle.gateway.egress.schema import load_config, route_to_yaml_dict
 from bot_bottle.gateway.egress.types import LOG_OFF
 from bot_bottle.gateway.policy_resolver import PolicyResolveError, PolicyResolver
+from bot_bottle.gateway.supervisor.mcp_dispatch import (
+    Handlers as DispatchHandlers,
+    MethodNotFoundError,
+    dispatch,
+    resolved_routes_payload,
+)
 from bot_bottle.supervisor import types as _sv
 
 
@@ -611,6 +616,11 @@ class MCPHandler(http.server.BaseHTTPRequestHandler):
 
         try:
             result = self._dispatch(req, config)
+        except MethodNotFoundError as e:
+            self._write_jsonrpc(
+                jsonrpc_error(req.id, ERR_METHOD_NOT_FOUND, f"method not found: {e}"),
+            )
+            return
         except _RpcClientError as e:
             self._write_jsonrpc(jsonrpc_error(req.id, e.code, e.message))
             return
@@ -633,41 +643,37 @@ class MCPHandler(http.server.BaseHTTPRequestHandler):
         self._write_jsonrpc(jsonrpc_result(req.id, result))
 
     def _dispatch(self, req: JsonRpcRequest, config: ServerConfig) -> object:
-        method = req.method
+        def check(params: dict[str, object]) -> object:
-        if method == "initialize":
+            return handle_check_proposal(
-            return handle_initialize(req.params)
+                params,
-        if method == "notifications/initialized":
+                resolver=self._resolver_or_fail(),
-            return None  # ack-only
+                source_ip=self.client_address[0],
-        if method == "tools/list":
+                identity_token=self._identity_token(),
-            return handle_tools_list(req.params)
-        if method == "tools/call":
-            # `list-egress-routes` is read-only introspection. The shared gateway
-            # has no static route table (routes are resolved per request by
-            # source IP), so answer it from the calling bottle's resolved policy.
-            # Otherwise the agent sees an empty allowlist and composes an egress
-            # proposal that *replaces* the live routes instead of extending them
-            # — silently dropping base routes like api.anthropic.com on approval.
-            if req.params.get("name") == _sv.TOOL_LIST_EGRESS_ROUTES:
-                return self._resolved_routes_payload()
-            resolver = self._resolver_or_fail()
-            source_ip = self.client_address[0]
-            token = self._identity_token()
-            # `check-proposal` is a non-blocking read of the calling bottle's
-            # own queue — attributed by (source_ip, identity_token) like a
-            # proposal, but it never queues or blocks.
-            if req.params.get("name") == _sv.TOOL_CHECK_PROPOSAL:
-                return handle_check_proposal(
-                    req.params, resolver=resolver,
-                    source_ip=source_ip, identity_token=token,
-                )
-            # The control plane attributes the proposal to the source-IP + token
-            # resolved bottle, so the one shared queue holds each bottle's
-            # proposal under its own id — no slug is asserted by this daemon.
-            return handle_tools_call(
-                req.params, config, resolver=resolver,
-                source_ip=source_ip, identity_token=token,
             )
-        raise _RpcClientError(ERR_METHOD_NOT_FOUND, f"method not found: {method}")
+
+        def propose(params: dict[str, object]) -> object:
+            return handle_tools_call(
+                params,
+                config,
+                resolver=self._resolver_or_fail(),
+                source_ip=self.client_address[0],
+                identity_token=self._identity_token(),
+            )
+
+        return dispatch(
+            req,
+            DispatchHandlers(
+                initialize=handle_initialize,
+                tools_list=handle_tools_list,
+                list_routes=lambda _params: resolved_routes_payload(
+                    self._resolver_or_fail(),
+                    self.client_address[0],
+                    self._identity_token(),
+                ),
+                check_proposal=check,
+                propose=propose,
+            ),
+        )
 
     def _identity_token(self) -> str:
         """The agent's per-bottle identity token from the request header (the
@@ -686,20 +692,6 @@ class MCPHandler(http.server.BaseHTTPRequestHandler):
             raise _RpcInternalError("supervise server has no policy resolver")
         return resolver
 
-    def _resolved_routes_payload(self) -> dict[str, object]:
-        """The calling bottle's live egress routes as the `list-egress-routes`
-        JSON payload, resolved by (source_ip, identity token). Fail-closed: an
-        unattributed source or an unreachable orchestrator yields an empty route
-        list (never another bottle's), courtesy of `resolve_client_context`."""
-        resolver = self._resolver_or_fail()
-        conf, _slug, _tokens = resolve_client_context(
-            resolver, self.client_address[0], self._identity_token(),
-        )
-        body = json.dumps(
-            {"routes": [route_to_yaml_dict(r) for r in conf.routes]}, indent=2,
-        )
-        return {"content": [{"type": "text", "text": body}], "isError": False}
-
     def _write_jsonrpc(self, body: bytes) -> None:
         self.send_response(200)
         self.send_header("Content-Type", "application/json")

tests/unit/test_supervise_server.py

@@ -13,6 +13,7 @@ import tempfile
 import threading
 import time
 import types
+import typing
 import unittest
 from pathlib import Path
 
@@ -47,6 +48,7 @@ from bot_bottle.gateway.supervisor.server import (
     jsonrpc_error,
     jsonrpc_result,
     parse_jsonrpc,
+    resolved_routes_payload,
     validate_proposed_file,
 )
 
@@ -701,9 +703,14 @@ class TestResolvedRoutesPayload(unittest.TestCase):
             "  - host: api.anthropic.com\n"
             "  - host: www.google.com\n"
         )
-        payload = _handler(
+        payload = resolved_routes_payload(
-            _FakeSuperviseResolver(bottle_id="b1", policy=policy)
+            typing.cast(
-        )._resolved_routes_payload()
+                supervise_server.PolicyResolver,
+                _FakeSuperviseResolver(bottle_id="b1", policy=policy),
+            ),
+            _SRC,
+            _TOK,
+        )
         assert payload is not None
         self.assertFalse(payload["isError"])  # type: ignore[index]
         data = json.loads(payload["content"][0]["text"])  # type: ignore[index]
@@ -713,9 +720,14 @@ class TestResolvedRoutesPayload(unittest.TestCase):
     def test_orchestrator_error_fails_closed_to_empty(self) -> None:
         # resolve_client_context swallows resolver errors → deny-all (empty),
         # never another bottle's routes.
-        payload = _handler(
+        payload = resolved_routes_payload(
-            _FakeSuperviseResolver(raises=True)
+            typing.cast(
-        )._resolved_routes_payload()
+                supervise_server.PolicyResolver,
+                _FakeSuperviseResolver(raises=True),
+            ),
+            _SRC,
+            _TOK,
+        )
         assert payload is not None
         data = json.loads(payload["content"][0]["text"])  # type: ignore[index]
         self.assertEqual([], data["routes"])
@@ -724,7 +736,13 @@ class TestResolvedRoutesPayload(unittest.TestCase):
         # A server without a resolver is a misconfig, not a mode: raise rather
         # than list anything.
         with self.assertRaises(_RpcInternalError):
-            _handler(None)._resolved_routes_payload()
+            _handler(None)._dispatch(
+                parse_jsonrpc(
+                    b'{"jsonrpc":"2.0","id":1,"method":"tools/call",'
+                    b'"params":{"name":"list-egress-routes"}}',
+                ),
+                ServerConfig(),
+            )
 
 
 class TestNonBlockingSupervise(unittest.TestCase):

tests/unit/test_supervisor_mcp_dispatch.py

@@ -0,0 +1,81 @@
+"""Unit tests for framework-neutral supervisor MCP dispatch."""
+
+from __future__ import annotations
+
+import unittest
+from dataclasses import dataclass
+
+from bot_bottle.gateway.supervisor.mcp_dispatch import (
+    Handlers,
+    MethodNotFoundError,
+    dispatch,
+)
+from bot_bottle.supervisor import types as _sv
+
+
+@dataclass(frozen=True)
+class _Request:
+    method: str
+    params: dict[str, object]
+
+
+class TestDispatch(unittest.TestCase):
+    def setUp(self) -> None:
+        self.calls: list[str] = []
+
+        def handler(name: str):
+            def call(_params: dict[str, object]) -> str:
+                self.calls.append(name)
+                return name
+
+            return call
+
+        self.handlers = Handlers(
+            initialize=handler("initialize"),
+            tools_list=handler("tools_list"),
+            list_routes=handler("list_routes"),
+            check_proposal=handler("check_proposal"),
+            propose=handler("propose"),
+        )
+
+    def request(self, method: str, **params: object) -> _Request:
+        return _Request(method=method, params=params)
+
+    def test_routes_protocol_methods(self) -> None:
+        self.assertEqual(
+            "initialize", dispatch(self.request("initialize"), self.handlers),
+        )
+        self.assertEqual(
+            "tools_list", dispatch(self.request("tools/list"), self.handlers),
+        )
+        self.assertIsNone(
+            dispatch(self.request("notifications/initialized"), self.handlers),
+        )
+
+    def test_routes_each_tool_class(self) -> None:
+        self.assertEqual(
+            "list_routes",
+            dispatch(
+                self.request("tools/call", name=_sv.TOOL_LIST_EGRESS_ROUTES),
+                self.handlers,
+            ),
+        )
+        self.assertEqual(
+            "check_proposal",
+            dispatch(
+                self.request("tools/call", name=_sv.TOOL_CHECK_PROPOSAL),
+                self.handlers,
+            ),
+        )
+        self.assertEqual(
+            "propose",
+            dispatch(self.request("tools/call", name=_sv.TOOL_EGRESS_ALLOW), self.handlers),
+        )
+
+    def test_unknown_method_is_typed(self) -> None:
+        with self.assertRaisesRegex(MethodNotFoundError, "unknown"):
+            dispatch(self.request("unknown"), self.handlers)
+
+
+if __name__ == "__main__":
+    unittest.main()