From 1cd556c3f64bb6015536bfecf22cf88178016255 Mon Sep 17 00:00:00 2001
From: Robert Helewka <r@helu.ca>
Date: Wed, 29 Apr 2026 12:04:42 -0400
Subject: [PATCH] =?UTF-8?q?fix(asgi):=20redirect=20/mcp=20=E2=86=92=20/mcp?=
 =?UTF-8?q?/=20for=20clients=20that=20omit=20the=20trailing=20slash?=
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Starlette's Mount("/mcp", ...) only matches /mcp/* paths. A POST to bare
/mcp falls through to the catch-all Django mount and returns 404. The
fast-agent MCP client and the README example both used the no-slash URL,
so the validator was never able to initialize a session — every call
landed in django.request.

Adds a 307 redirect at /mcp so any client URL works, and points the
validator config at /mcp/ directly to skip the redirect round-trip.
Also gitignores fastagent.jsonl (a runtime log file fast-agent writes
into the working directory).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 mnemosyne/mnemosyne/asgi.py     | 10 +++++++++-
 validator/.gitignore            |  1 +
 validator/README.md             |  2 +-
 validator/fastagent.config.yaml |  2 +-
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/mnemosyne/mnemosyne/asgi.py b/mnemosyne/mnemosyne/asgi.py
index 675c974..3c0472f 100644
--- a/mnemosyne/mnemosyne/asgi.py
+++ b/mnemosyne/mnemosyne/asgi.py
@@ -20,7 +20,7 @@ django.setup()
 
 from django.core.asgi import get_asgi_application  # noqa: E402
 from starlette.applications import Starlette  # noqa: E402
-from starlette.responses import JSONResponse  # noqa: E402
+from starlette.responses import JSONResponse, RedirectResponse  # noqa: E402
 from starlette.routing import Mount, Route  # noqa: E402
 
 from mcp_server.server import mcp  # noqa: E402
@@ -35,6 +35,13 @@ async def health(request):
     return JSONResponse({"status": "ok"})
 
 
+async def mcp_redirect(request):
+    """Bare /mcp → /mcp/ — MCP clients that omit the trailing slash hit
+    Starlette's Mount which only matches /mcp/* paths, falling through to
+    Django and returning 404. A 307 preserves the POST body."""
+    return RedirectResponse(url="/mcp/", status_code=307)
+
+
 @asynccontextmanager
 async def lifespan(app):
     async with mcp_http_app.lifespan(app), mcp_sse_app.lifespan(app):
@@ -44,6 +51,7 @@ async def lifespan(app):
 app = Starlette(
     routes=[
         Route("/mcp/health", health),
+        Route("/mcp", mcp_redirect, methods=["GET", "POST"]),
         Mount("/mcp/sse", app=mcp_sse_app),
         Mount("/mcp", app=mcp_http_app),
         Mount("/", app=application),
diff --git a/validator/.gitignore b/validator/.gitignore
index a7e961a..092fa9a 100644
--- a/validator/.gitignore
+++ b/validator/.gitignore
@@ -1,4 +1,5 @@
 fastagent.secrets.yaml
+fastagent.jsonl
 .venv/
 *.egg-info/
 __pycache__/
diff --git a/validator/README.md b/validator/README.md
index 0aaa211..8c1658e 100644
--- a/validator/README.md
+++ b/validator/README.md
@@ -55,7 +55,7 @@ cd mnemosyne/
 uvicorn mnemosyne.asgi:app --host 0.0.0.0 --port 22091 --workers 1
 ```
 
-By default the validator points at `http://localhost:22091/mcp`. If your Mnemosyne is on another host, override `mcp.servers.mnemosyne.url` in `fastagent.secrets.yaml`.
+By default the validator points at `http://localhost:22091/mcp/` (note the trailing slash — Starlette's `Mount` only matches paths under the mount prefix, so `/mcp` without the slash falls through to Django). If your Mnemosyne is on another host, override `mcp.servers.mnemosyne.url` in `fastagent.secrets.yaml`.
 
 ## Run the validator
 
diff --git a/validator/fastagent.config.yaml b/validator/fastagent.config.yaml
index bd6a6e7..b0b07f5 100644
--- a/validator/fastagent.config.yaml
+++ b/validator/fastagent.config.yaml
@@ -27,6 +27,6 @@ mcp:
     # override the URL in fastagent.secrets.yaml or via Ansible if remote.
     mnemosyne:
       transport: http
-      url: "http://localhost:22091/mcp"
+      url: "http://localhost:22091/mcp/"
       # Bearer token in fastagent.secrets.yaml (provisioned via
       # `python manage.py create_mcp_token <user>`).