test(mcp): pin the typed unknown-tool refusal on the rmcp wire

[ScriptedAlchemy]

Fixes #2645

Cause: stale pin, not a production regression

rmcp_wire_matrix_matches_raw_dispatch_initialize_tools_and_resources failed at the code assertion:

assertion `left == right` failed: handler error code is a host-visible protocol contract
  left: Number(-32602)
 right: Number(-32603)

The line just before that assertion, assert_last_response_matches_raw_dispatch, already passed. It compares the whole rmcp wire frame with the raw McpServer::handle_request frame for the same request, so the two frames were identical in every field. Only the literal code was stale.

#2517 (a0b5987) changed unknown_tool_error from untyped TraceDecayError::Config, which rendered as -32603, to project_route("unknown_tool", retryable=false). It also added unknown_tool to the invalid_request kinds in project_route_problem_kind. That PR re-pinned the mcp_suite frames but missed this lib test. -32602 is also the code the MCP spec gives for an unknown tool.

Recent changes I checked:

• fix(mcp): serve user settings on projectless MCP sessions #2605 (projectless config tools) and fix(sessions)!: scope stale session-store refusals and reset #2613/fix(sessions): scope every session-store refusal to sessions #2648 (scoped refusals) don't touch unknown-tool routing.
• The one-problem-shape lane (fleet/one-problem-shape, 175446a632, no PR yet) moves typed problems for isError tool results into structuredContent. It doesn't touch JSON-RPC error frames, unknown_tool_error, or rmcp.rs, so it doesn't overlap with this change.

Change

The test now pins the whole wire error object instead of the code alone, so any drift in the message or typed data fails too:

{"code": -32602,
 "message": "tool project route failed: reason_code=unknown_tool retryable=false: unknown tool: tracedecay_not_a_tool",
 "data": {"tool": "tracedecay_not_a_tool", "code": "unknown_tool", "reason_code": "unknown_tool",
          "kind": "invalid_request", "retryable": false, "detail": "unknown tool: tracedecay_not_a_tool"}}

No production code changes.

Fail before / pass after

• origin/master d842ec3: FAILED, left: Number(-32602) right: Number(-32603) (output above). It also failed in all 18 full-lib-suite runs of the unmodified master binary.
• This branch, after merging master 8d4fd5e: rmcp_wire_matrix_matches_raw_dispatch_initialize_tools_and_resources, raw_json_rpc_wire_frames_are_unchanged_by_the_typed_envelope, and rmcp_tool_call_honours_the_request_meta_caller_deadline all pass: test result: ok. 3 passed; 0 failed; ... 769 filtered out. It also passed in every loaded full-lib-suite run of a binary with this change.

Runtime journey (built CLI, isolated profile)

hauler exec -- cargo build -p tracedecay-cli --no-default-features --features production --locked. The daemon ran under systemd-run --user --scope -p MemoryMax=6G -p MemorySwapMax=1G ... tracedecay daemon run --socket $HOME/.tracedecay/daemon.sock, with a scratch HOME, a one-file git project, and tracedecay init. Then tracedecay serve -p <project> was driven over stdio like an MCP host:

initialize.serverInfo: {"name": "tracedecay", "version": "1.0.0-beta.62+b25a8f9f9ec62bdb40670c23b543d8ec0f0bf943.dirty"}
tools/call tracedecay_not_a_tool: {"jsonrpc": "2.0", "id": 2, "error": {"code": -32602, "message": "tool project route failed: reason_code=unknown_tool retryable=false: unknown tool: tracedecay_not_a_tool", "data": {"code": "unknown_tool", "detail": "unknown tool: tracedecay_not_a_tool", "kind": "invalid_request", "reason_code": "unknown_tool", "retryable": false, "tool": "tracedecay_not_a_tool"}}}
tools/call tracedecay_status: isError= None text[:120]= {"graph_statistics":{"reason":"exact_scope_generation_not_ready","state":"unavailable"},...

The shipped server answers exactly the pinned frame.

Checks

• cargo clippy -p tracedecay --all-targets --features test-transport -- -D warnings: clean
• cargo fmt --all -- --check: clean
• ripwire --quality-delta: gating=0; the only rows are minor verbosity and churn on the test itself

[changeset-bot]

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Latest commit: 19e5115

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[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-29T15:38:11.143815Z	19e5115	PR opened

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