# `ConduitMcp.Protocol.Legacy`
[🔗](https://github.com/nyo16/conduit_mcp/blob/v0.11.0/lib/conduit_mcp/protocol/legacy.ex#L1)

Shapes a neutral handler result (`t:ConduitMcp.Handler.result/0`) into the
JSON-RPC 2.0 response map of the legacy (`initialize`-negotiated) protocol
era.

`{:ok, result}` becomes a success response; `{:error, code, message, data}`
becomes an error response, with a `"data"` member only when `data` is not
`nil`. Codes pass through unchanged.

## Resource not found

The legacy era answers an unknown resource with `-32002`
(`resource_not_found/0`). That is also the code a `handle_read_resource/2`
callback returns in every authoring mode: the modern shaper,
`ConduitMcp.Protocol.Modern`, rewrites it to `-32602`, which is what
`2026-07-28` prescribes.

# `resource_not_found`

```elixir
@spec resource_not_found() :: integer()
```

The legacy-era "resource not found" code, `-32002`.

Return it from `handle_read_resource/2` for an unknown URI; the modern era
sees `-32602` instead (see the moduledoc).

# `to_response`

```elixir
@spec to_response(
  ConduitMcp.Protocol.json_rpc_id() | nil,
  ConduitMcp.Handler.result()
) :: map()
```

Builds the JSON-RPC response for request `id` from a neutral `result`.

## Examples

    iex> ConduitMcp.Protocol.Legacy.to_response(1, {:ok, %{}})
    %{"jsonrpc" => "2.0", "id" => 1, "result" => %{}}

    iex> ConduitMcp.Protocol.Legacy.to_response(1, {:error, -32601, "Nope", nil})
    %{"jsonrpc" => "2.0", "id" => 1, "error" => %{"code" => -32601, "message" => "Nope"}}

---

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