[Megaprompting]

What broke

Since 2026-10-04 Claude Code has failed every connection to the Torque MCP server with -32010. A pass-through stdio shim recorded the handshake from Claude Code 2.1.308 (desktop-bundled) and 2.1.310 (CLI):

1. The client sends server/discover (id server-discover-probe-1, carrying the modern _meta).
2. Torque returns the version list 2026-07-28, 2025-11-25, 2025-06-18 and pins the connection modern.
3. On the same connection, the client sends initialize with protocolVersion: 2025-11-25.
4. Torque refuses it: "eras never mix".

Discover was already version-exempt because it is the request a client uses to learn which versions exist. Pinning an era on that request turned it into a choice the client never made.

The fix

server/discover still answers with a modern-shaped result and still needs no version, but it pins no era. The era is pinned by the first message that carries one:

• initialize pins legacy.
• A request carrying _meta io.modelcontextprotocol/protocolVersion pins modern.

The rest of "eras never mix" is unchanged, and the tests still assert each case:

• server/discover after initialize is refused.
• A modern-marked request on a legacy connection is refused (C1).
• initialize after a real modern request is refused (new test, replacing the old discover-then-initialize one).
• Ambiguous or incomplete handshakes pin nothing (D1, D3, C10, E2).

The refusal for an unpinned connection no longer names discover as a way to pin an era.

Tests

• Two tests changed meaning: "discover pins modern" became "discover pins nothing", and "initialize after discover is refused" became "succeeds" plus the new modern-request refusal test.
• C14 and D10 now pin modern with a real modern request, so their "on modern" claims stay true.
• New falsifier: the exact recorded two-line handshake, replayed over stdio. It fails with the production -32010 message on the unpatched kernel and passes after the fix.
• npm test: all 16 suites green (rpc 58/58).

Wire trace: before and after

Before (installed 1.0.0, Claude Code 2.1.310):

C->S {"id":"server-discover-probe-1","method":"server/discover", ...}
S->C {"id":"server-discover-probe-1","result":{"protocolVersions":["2026-07-28","2025-11-25","2025-06-18"], ...}}
C->S {"method":"initialize","params":{"protocolVersion":"2025-11-25", ...},"id":0}
S->C {"id":0,"error":{"code":-32010,"message":"this connection is pinned to the modern era and initialize belongs to the other one — eras never mix on a connection; reconnect to switch"}}

After (this branch, same client, same one-turn claude -p --strict-mcp-config call):

C->S {"id":"server-discover-probe-1","method":"server/discover", ...}
S->C {"id":"server-discover-probe-1","result":{"protocolVersions":["2026-07-28","2025-11-25","2025-06-18"], ...,"resultType":"complete", ...}}
C->S {"method":"initialize","params":{"protocolVersion":"2025-11-25", ...},"id":0}
S->C {"id":0,"result":{"protocolVersion":"2025-11-25","capabilities":{"tools":{},"resources":{},"prompts":{}},"serverInfo":{"name":"torque-mcp","version":"1.0.0"}}}
C->S {"method":"notifications/initialized"}
C->S {"method":"tools/list","id":1}   -> result
C->S {"method":"prompts/list","id":2} -> result
C->S {"method":"resources/list","id":3} -> result

In its own system/init event, Claude Code reports {"name":"tq","status":"connected"} and lists the mcp__tq__* tools.

Not in this PR

• Nothing is installed into the plugin cache. Users get the fix when they update the plugin after this merges.

🤖 Generated with Claude Code