feat(mcp): /mcp reconnect <name> for identity drift (closes part of #110)#115
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feat(mcp): /mcp reconnect <name> for identity drift (closes part of #110)#115
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C2b implementation per RFC #110. Identity-drift only — append / edit / reorder / remove drift cases surface a clear "restart Reasonix to apply" message instead of mutating the registry or prefix mid-session. The graduated permissive policy from the empirical spike (#113) needs API work on `ImmutablePrefix` (replaceTool / removeTool) before the other drift kinds can take effect mid-session; that's a follow-up PR. Touch: - `src/mcp/registry.ts`: new `McpClientHost = { client: McpClient }` indirection on BridgeOptions. Tool closures resolve the live client via `host.client` at call time, so reconnect can swap the underlying socket without re-bridging tools. - `src/mcp/reconnect.ts` (new): `reconnectMcpServer({ host, spec, beforeTools })` re-handshakes a fresh transport, classifies drift, swaps `host.client` only on identity, closes the new client cleanly on refusal so the old one stays untouched. - `src/cli/ui/slash/handlers/mcp.ts`: third subcommand `reconnect <name>`, fires async, reports via `ctx.postInfo` with the lifecycle `↻ reconnect…` / `✓ connected` / `✖ failed` formatter. - `src/cli/ui/mcp-lifecycle.ts`: `reconnect` state added to the union. - `src/cli/ui/slash/types.ts`: `McpServerSummary.client?` replaced by `host: McpClientHost`. `McpClient` import dropped (now via host). - `src/cli/ui/mcp-browse.ts`: `/resource` and `/prompt` read through `server.host.client`. Disconnected-server warnings dropped — host always carries a client now. - `src/cli/commands/chat.tsx`: builds the host at bridge time, stores it on the summary. Tests: - `tests/mcp-reconnect.test.ts`: 2 cases for spec_parse early returns. - `tests/mcp-integration.test.ts`: live test that bridge + host indirection routes a swapped client correctly through registry.dispatch. - `tests/slash.test.ts`: 3 cases for the slash dispatch (lifecycle line emission, unknown-name rejection with hint, no-arg usage). - `tests/mcp-browse.test.ts`: server() helper updated to accept `client` and wrap in host shape. Closes part of #110 (identity case only). Append/edit/reorder/remove mid-session handling deferred — needs ImmutablePrefix surgery.
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Stage E2 of the C2b follow-ups: when /mcp reconnect finds the server added new tools at the END of its tool list, register them mid-session and addTool the prefix instead of refusing. Drift kinds the reconnect now accepts: - identity → free swap, ~95% cache hit (was already shipped in #115) - append → register new tools, ~95% cache hit (the new chunks land in cache too, per benchmarks/spike-mcp-reconnect data) - edit / reorder / remove → still refused with "restart Reasonix" Touch: - src/mcp/registry.ts — extract `registerSingleMcpTool(mcpTool, env)` + new `BridgeEnv` type (resolved bridge environment captured at first-bridge time). bridgeMcpTools' return shape gains `env` so reconnect can re-use the same options. - src/cli/ui/slash/types.ts — McpServerSummary gains `bridgeEnv: BridgeEnv` so the append handler has everything it needs to register a new tool without redoing the whole bridge. - src/cli/commands/chat.tsx — captures bridge.env onto the summary. - src/mcp/reconnect.ts — accepts identity (always) plus append (if caller passes accept: ["identity", "append"]). On append, returns addedTools so the caller can register them. Identity is forced- accepted regardless of `accept` because it's free. - src/cli/ui/mcp-append.ts (new) — `applyMcpAppend(loop, target, addedTools)` calls registerSingleMcpTool + prefix.addTool + refreshes target.report. Accepted-tools-only counting handles the unnamed-tool defensive case. - src/cli/ui/mcp-reconnect-kickoff.ts — gains optional `applyAppend` callback. When set, opts the reconnect into ["identity", "append"]; when missing, behaviour is unchanged from #115. - src/cli/ui/slash/handlers/mcp.ts + src/cli/ui/McpBrowser.tsx + src/cli/ui/App.tsx — both surfaces wire applyMcpAppend through. - tests/mcp-append.test.ts (new) — 4 cases: registry registration, fingerprint invalidation, summary refresh, defensive skip on unnamed tools. Closes most of #110. Edit / reorder / remove mid-session remain as follow-up issues — each requires new ImmutablePrefix API (replaceTool / removeTool) + cache-reset announcement.
This was referenced May 2, 2026
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Closes part of #110.
Scope
/mcp reconnect <name>for the identity-drift case only. Append / edit / reorder / remove drift surface a clear "restart Reasonix to apply" message instead of mutating the registry or prefix mid-session.Why split this way: the graduated-permissive policy from the empirical spike (#113) needs API work on
ImmutablePrefix(replaceTool / removeTool) before the other drift kinds can take effect mid-session. That's a follow-up PR. This one delivers the most common reconnect case (server crashed / restarted with same tool surface, user wants to retry without restarting Reasonix).Touch
Indirection layer:
src/mcp/registry.ts— newMcpClientHost = { client: McpClient }exposed viaBridgeOptions.host. Tool closures resolvehost.clientat call time, so swapping the client doesn't require re-bridging tools.New module:
src/mcp/reconnect.ts—reconnectMcpServer({ host, spec, beforeTools })re-handshakes a fresh transport, classifies drift viaclassifyToolListDrift(feat(mcp): tool-list drift classifier — groundwork for #110 C2b #114), swapshost.clientonly on identity, closes the new client cleanly on refusal so the old one stays untouched.Slash:
src/cli/ui/slash/handlers/mcp.ts— third subcommandreconnect <name>, fires async, reports viactx.postInfowith↻ reconnect…/✓ connected/✖ failed.src/cli/ui/mcp-lifecycle.ts—reconnectstate added to the union.Type / consumer churn:
src/cli/ui/slash/types.ts—McpServerSummary.client?: McpClientreplaced byhost: McpClientHost. The mutable wrapper IS the swap point.src/cli/ui/mcp-browse.ts—/resourceand/promptread throughserver.host.client. Dropped the "server not connected" branches — host always carries a client now.src/cli/commands/chat.tsx— builds host at bridge time, stores on summary.Tests
tests/mcp-reconnect.test.ts(new) — 2 cases for spec_parse early returnstests/mcp-integration.test.ts— live test that bridge + host indirection routes a swapped client correctly throughregistry.dispatchtests/slash.test.ts— 3 cases for slash dispatch (lifecycle line emission, unknown-name rejection with hint, no-arg usage)tests/mcp-browse.test.ts—server()helper updated to acceptclientand wrap in host shapenpm run verifygreen: 1778 tests.Deferred to follow-up
ImmutablePrefix.addToolto be safely callable from outside the loop, plusToolRegistrymutation that doesn't break the prefix invariantImmutablePrefix.replaceTool(doesn't exist yet)ImmutablePrefix.removeTool+ handling the cache reset announcementrkeybind inMcpBrowser— reuse this slash once landed--strictflag — opt-in to refusing even identity reconnects (specialised use case)Each of those is its own PR with its own design call.
Test plan
npm run verifypasses (1778 tests, +6 new)spec_parsereason/mcp reconnect <name>, confirm the lifecycle lines appear and tools keep working