# `ConduitMcp.Handler`
[🔗](https://github.com/nyo16/conduit_mcp/blob/v0.10.1/lib/conduit_mcp/handler.ex#L1)

Routes JSON-RPC 2.0 MCP requests to a server module's behaviour callbacks.

`handle_request/3` is the single entry point: transports decode the
request body, hand the resulting map to this module, and serialize the
returned map back out. The handler itself is stateless — it does not own
the server module, the connection, or any process state. Each request
is independent and can run concurrently in its own Bandit process.

## Routed methods

- `initialize` — version negotiation and capability advertisement
- `ping` — round-trip liveness check
- `tools/list`, `tools/call`
- `resources/list`, `resources/templates/list`, `resources/read`
- `resources/subscribe`, `resources/unsubscribe`
- `prompts/list`, `prompts/get`
- `completion/complete`
- `logging/setLevel`
- `tasks/get`, `tasks/cancel`, `tasks/result`, `tasks/list`
- `notifications/initialized`, `notifications/cancelled`

Unknown methods return `-32601 Method not found`. Unknown notifications
are logged and dropped (per JSON-RPC notification semantics).

## Capability detection

When the server module defines `__capabilities__/0` (typically generated
by `ConduitMcp.Endpoint`), it is consulted for the `initialize` reply.
Otherwise the base `tools`/`resources`/`prompts` set is used.
Capability flags for optional features (`completions`, `logging`,
`resources.subscribe`) are overlaid at runtime based on which callbacks
the server exports, via `ConduitMcp.ServerMeta`.

## Telemetry

Emits these events:

- `[:conduit_mcp, :request, :stop]` — every request, with
  `%{duration: <native>}` and metadata `%{method, server_module, status}`.
- `[:conduit_mcp, :tool, :execute]` — per `tools/call`.
- `[:conduit_mcp, :resource, :read]` — per `resources/read`.
- `[:conduit_mcp, :prompt, :get]` — per `prompts/get`.
- `[:conduit_mcp, :request, :cancelled]` — when
  `notifications/cancelled` is received.

## Cancellation

The handler stashes the request id into `conn.assigns[:mcp_request_id]`
before dispatch and uses `try/after` to clear any cancellation flag
after the response is produced. Tools poll
`ConduitMcp.Cancellation.cancelled?(conn)` for cooperative aborts.

# `handle_request`

Handles an MCP request and returns a JSON-RPC response.
Emits telemetry events for monitoring and metrics.

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*Consult [api-reference.md](api-reference.md) for complete listing*