docs: add MCP namespace client is closing: EOF recovery runbook (#543)
Adds docs/mcp-namespace-eof-recovery.md documenting the correct recovery path when a Gitea MCP namespace (gitea-author/reviewer/merger/tools) returns `client is closing: EOF`. Satisfies acceptance criterion 7 of #543: symptom, root cause (closed client transport vs a live-but-stale process), the sanctioned reconnect/relaunch sequence, diagnostics to capture, and how test_mcp_conn.py reproduces the registered-vs-callable gap. Distinguishes this transport-close failure from the ps-based stale-runtime family in #531/#544 and reinforces the no-direct-import guard (#558). Docs-only; no code or test behavior changed. Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
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Claude Opus 4.8
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# Recovering from `client is closing: EOF` on a Gitea MCP namespace (#543)
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## Symptom
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A tool call through a Gitea MCP namespace — `gitea-author`, `gitea-reviewer`,
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`gitea-merger`, or the shared `gitea-tools` namespace — fails immediately with:
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```
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client is closing: EOF
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```
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Every subsequent call to that same namespace returns the same error, including
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cheap read tools such as `gitea_whoami` and `gitea_list_profiles`. Other MCP
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servers registered with the same client (for example `context7`) keep working,
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so this is **not** a global MCP-client outage.
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## Why this is not a code defect
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This failure is a **transport-level** condition in the IDE / MCP client manager,
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not a missing or broken tool:
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- The tool can be present and registered in the Python `FastMCP` tool manager.
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- Direct Python inspection of the server confirms the tool exists.
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- Running the server manually and sending JSON-RPC over stdio works fine.
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The client manager entered a closed state after the backing subprocess for that
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namespace terminated (or was killed) behind its back. Once closed, the client
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does **not** re-spawn the child on the next tool call — it just replays
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`client is closing: EOF`. The OS process may even still be alive if a parent
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language-server process is holding the stdio pipes open.
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This is the canonical "registered in FastMCP ≠ callable through the namespace"
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false-ready state. It is distinct from the **stale-runtime** family in #531 /
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#544, where the process is reachable but running behind `master`; that case is
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detected by the `ps`-based `_check_mcp_runtimes_diagnostics` in
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`gitea_mcp_server.py`. The EOF case is a dead/closed transport, not a stale one,
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so the `ps` check alone will not surface it.
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## Recovery path
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Do the steps in order. Stop as soon as a live namespace call succeeds.
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1. **Confirm the blast radius.** Call a cheap read tool on the failing namespace
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(`gitea_whoami` or `gitea_list_profiles`). Then call the same tool on a
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different MCP server (e.g. `context7`).
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- Only the Gitea namespace fails → single-namespace transport close. Continue.
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- Every server fails → restart the whole MCP client, not just one namespace.
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2. **Reconnect the namespace through the client, not the shell.** Use the IDE /
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client MCP-reconnect action for that server entry (in Claude Code:
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`/mcp` → reconnect the affected `gitea-*` server). Reconnecting forces the
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client to spawn a fresh subprocess and re-open the pipe. This clears the
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closed-client state that a bare `kill`/respawn from a terminal does **not**.
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3. **Do not "fix" it by importing the server or poking the process.** Reaching
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for `python -c 'import gitea_mcp_server ...'`, raw JSON-RPC from a shell, or
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killing PIDs to force a respawn does not restore the *client's* view of the
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namespace and violates the daemon-import guard (#558,
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`docs/mcp-daemon-import-guard.md`). The only sanctioned repair is a client
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reconnect / relaunch.
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4. **Verify through the same path the workflow will use.** After reconnect, call
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the specific tool the blocked workflow needs — not just any tool — through
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the target namespace. For a merge that means calling the merger-authorized
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adoption/merge tool through `gitea-merger`. A green `gitea_whoami` on one
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namespace does **not** prove another namespace or another tool is callable.
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5. **If reconnect does not clear it,** relaunch the client entirely, then repeat
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step 4. If EOF persists after a full relaunch, the backing subprocess is
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failing to start — inspect its stderr / launch config (command path, venv,
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`*_MCP_CONFIG`, `*_MCP_PROFILE` env) rather than retrying the call.
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## Diagnostics to capture when reporting EOF
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Include all of these so the failure is actionable and reproducible:
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- **Namespace name** that returned EOF (`gitea-author` / `gitea-reviewer` /
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`gitea-merger` / `gitea-tools`).
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- **Tool** that was called and the **exact** error string.
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- **PID** of the backing process (if any) and whether it was still alive.
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- **Profile / env** for that namespace (execution profile, `*_MCP_PROFILE`,
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worktree binding such as `GITEA_AUTHOR_WORKTREE`).
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- **Config path** the client launched the server from.
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- Result of the **cross-server control** call (did `context7` succeed?).
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## Reproducing the registered-vs-callable gap
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`test_mcp_conn.py` performs a full JSON-RPC handshake
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(`initialize` → `initialized` → `tools/list`) plus a direct tool call against a
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namespace, which is what distinguishes "registered in FastMCP" from "callable
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through the client." Use it to confirm a namespace is genuinely reachable after
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a reconnect. It probes a namespace end-to-end; a namespace that returns EOF at
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the client fails this handshake, while `ps`-only checks still report the process
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as present.
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## Do-not list during EOF recovery
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- Do **not** retry a blocked merge/adoption until the required tool is confirmed
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callable through the merger-authorized namespace (see #543 canonical handoff).
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- Do **not** clean, reset, or rebind a **foreign** worktree to work around the
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error.
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- Do **not** bypass the namespace with direct imports, raw API/curl, or
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in-memory state restoration.
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## Related
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- #531 / #544 — stale-runtime detection (`ps`-based); sibling failure mode.
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- #558 / `docs/mcp-daemon-import-guard.md` — why shell imports are not a repair.
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- `docs/mcp-client-registration.md` — per-server registration contract.
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