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docs: make the local CIMD smoke deterministic, and fix two HTTPS-only claims

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Copilot review round 4, four findings, all correct.

The CIMD-off / CIMD-on pair the smoke guide documents is not a control without
clearing OAuth state first: tokens and the registered client persist in
oauth.json independently of the install-wide CIMD toggle, and the Inspector
reuses valid stored tokens before prompting — so a leftover grant from an
earlier CIMD-on run makes the CIMD-off phase connect and the negative control
silently proves nothing. Both the spec's pair and the walkthrough in
docs/test-servers.md now say to clear state (or isolate MCP_STORAGE_DIR) first.

The composable server announces its MCP endpoint, not the metadata document —
`server-composable.ts` prints a URL ending in `/mcp`. The guide called the
announced URL a metadata URL; it now says to take the origin from that line and
append `/client-metadata.json`.

Two general statements elsewhere in the same file still defined CIMD as always
HTTPS (the glossary row, and the Stytch section's opening), so a reader
following them would have rejected the loopback fixture the same file now
documents. Both note the exemption; the Stytch examples stay HTTPS, which they
are.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GfHQ8vMm5NBgzbUJ6UwxmB
Signed-off-by: cliffhall <cliff@futurescale.com>
This commit is contained in:
cliffhall 2026-09-11 03:32:02 -04:00
commit d7f90144c6
2 changed files with 16 additions and 4 deletions
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8
docs/test-servers.md
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@ -578,6 +578,14 @@ listener to hold the document and setting `NODE_TLS_REJECT_UNAUTHORIZED=0` in th
environment so its own fetch of that document would succeed. That workaround is no longer needed — if environment so its own fetch of that document would succeed. That workaround is no longer needed — if
you find it in a script or an older note, delete it. you find it in a script or an older note, delete it.
⚠️ **Clear OAuth state before the run if you have connected to this fixture before.** Tokens and the
registered client persist in `~/.mcp-inspector/storage/oauth.json` independently of the install-wide
CIMD toggle, and the Inspector reuses valid stored tokens before prompting — so a leftover grant can
carry a run that the registration path never actually completed, which is the same
"it connected, therefore CIMD worked" trap `supportDCR: false` exists to close. Use **Clear OAuth
state and disconnect** (Server Settings → Authorization), or point `MCP_STORAGE_DIR` at a throwaway
directory, which additionally survives a restarted fixture having forgotten a client it once issued.
With that in place: set the metadata URL in Client settings, connect, and open **Connection Info**. With that in place: set the metadata URL in Client settings, connect, and open **Connection Info**.
It should read `Client registration — Client ID Metadata (CIMD)` with the **client id equal to the It should read `Client registration — Client ID Metadata (CIMD)` with the **client id equal to the
metadata URL**, which is what CIMD means and what distinguishes it from a DCR-issued metadata URL**, which is what CIMD means and what distinguishes it from a DCR-issued

12
specification/v2_auth_smoke_testing.md
View file

@ -40,7 +40,7 @@ Web uses `http://localhost:6274/oauth/callback` on the main app server — not t
| --------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | --------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Static / preregistered client** | You supply `oauthClientId` and optionally `oauthClientSecret` in Server Settings. Inspector skips DCR and uses your credentials. | | **Static / preregistered client** | You supply `oauthClientId` and optionally `oauthClientSecret` in Server Settings. Inspector skips DCR and uses your credentials. |
| **DCR** | Dynamic Client Registration (RFC 7591). Inspector registers at the AS `registration_endpoint` on first connect; no client id in config. | | **DCR** | Dynamic Client Registration (RFC 7591). Inspector registers at the AS `registration_endpoint` on first connect; no client id in config. |
| **CIMD** | Client ID Metadata Document (SEP-991). Inspector uses an HTTPS metadata URL as `client_id` when the AS advertises `client_id_metadata_document_supported`. | | **CIMD** | Client ID Metadata Document (SEP-991). Inspector uses an HTTPS metadata URL as `client_id` when the AS advertises `client_id_metadata_document_supported` — or a plain `http://` one on `localhost` / `127.0.0.1` / `[::1]`, the loopback exemption added in [#2305](https://github.com/modelcontextprotocol/inspector/issues/2305) for local fixtures. |
| **Client credentials grant** | OAuth 2.0 machine-to-machine `grant_type=client_credentials`. **Not** what we mean by “static client credentials” here. Inspector does not implement this grant yet ([#1225](https://github.com/modelcontextprotocol/inspector/issues/1225)). | | **Client credentials grant** | OAuth 2.0 machine-to-machine `grant_type=client_credentials`. **Not** what we mean by “static client credentials” here. Inspector does not implement this grant yet ([#1225](https://github.com/modelcontextprotocol/inspector/issues/1225)). |
## Prerequisites ## Prerequisites
@ -395,7 +395,7 @@ The full `redirect_uris` list also includes other localhost ports and MCPJam app
#### Why MCPJam’s document works with Inspector #### Why MCPJam’s document works with Inspector
CIMD treats the metadata **HTTPS URL** as the OAuth `client_id`. On authorize, Stytch (or any CIMD-capable AS) fetches that JSON and checks: CIMD treats the metadata **HTTPS URL** as the OAuth `client_id` (loopback `http://` is the one exemption — see [§ local fallback](#local-fallback-composable-test-server); everything in this Stytch section is HTTPS). On authorize, Stytch (or any CIMD-capable AS) fetches that JSON and checks:
1. The document’s `client_id` field matches the URL. 1. The document’s `client_id` field matches the URL.
2. The `redirect_uri` on the request appears **exactly** in `redirect_uris`. 2. The `redirect_uri` on the request appears **exactly** in `redirect_uris`.
@ -521,9 +521,13 @@ node test-servers/build/server-composable.js --config test-servers/configs/oauth
The server announces its URL on **stderr**, and walks to the next free port on `EADDRINUSE` — read the announced URL rather than assuming 8092. The server announces its URL on **stderr**, and walks to the next free port on `EADDRINUSE` — read the announced URL rather than assuming 8092.
Since [#2305](https://github.com/modelcontextprotocol/inspector/issues/2305) a loopback `http://` metadata URL is a **valid persisted `client.json` setting and a valid entry in the settings form**, not a test-only affordance — `getCimdClientMetadataUrlError` exempts `localhost`, `127.0.0.1` and `[::1]`, the same three literals the SDK exempts for token endpoints. So point `clientMetadataUrl` straight at the URL the fixture announced (`http://127.0.0.1:8092/client-metadata.json` on its configured port) with no HTTPS listener. Before that change the exemption existed only in `ensureCimdClientRegistration`, for an already-stored `client_id`, and driving this by hand needed a self-signed HTTPS listener plus `NODE_TLS_REJECT_UNAUTHORIZED=0`. Since [#2305](https://github.com/modelcontextprotocol/inspector/issues/2305) a loopback `http://` metadata URL is a **valid persisted `client.json` setting and a valid entry in the settings form**, not a test-only affordance — `getCimdClientMetadataUrlError` exempts `localhost`, `127.0.0.1` and `[::1]`, the same three literals the SDK exempts for token endpoints. So `clientMetadataUrl` can point straight at the document this fixture serves, with no HTTPS listener. Before that change the exemption existed only in `ensureCimdClientRegistration`, for an already-stored `client_id`, and driving this by hand needed a self-signed HTTPS listener plus `NODE_TLS_REJECT_UNAUTHORIZED=0`.
With CIMD off in Client Settings, connect + authenticate should **fail**; with CIMD on and that local metadata URL, it should **succeed**. `docs/test-servers.md` has the full walkthrough, including the `redirect_uris` port trap. ⚠️ **The server announces its MCP endpoint, not the metadata URL** — the line on stderr ends in `/mcp`. Take the **origin** (host and port) from it and append `/client-metadata.json`: an announced `http://127.0.0.1:8092/mcp` means `clientMetadataUrl` is `http://127.0.0.1:8092/client-metadata.json`. Don't assume 8092; the fixture walks past a taken port.
⚠️ **Clear OAuth state before each phase, or neither outcome below is deterministic.** Tokens and the registered client persist in `~/.mcp-inspector/storage/oauth.json` independently of the install-wide CIMD toggle, and the Inspector reuses valid stored tokens before prompting — so a leftover grant from an earlier CIMD-on run makes the CIMD-off phase *connect*, and the negative control silently proves nothing. Use **Clear OAuth state and disconnect** (Server Settings → Authorization) before the off phase and again between the off and on phases. Pointing `MCP_STORAGE_DIR` at a throwaway directory for the whole run is the stronger version, and also survives a restarted fixture having forgotten a client it once issued.
With that state cleared: with CIMD off in Client Settings, connect + authenticate should **fail**; with CIMD on and that local metadata URL, it should **succeed**. `docs/test-servers.md` has the full walkthrough, including the `redirect_uris` port trap.
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