jochen
78817c949e
The node's runtime launches a tools bundle as a process and speaks MCP over stdio to it, so a tool may be written in any language and the transport stays in the runtime (ADR 0039's refusal, kept). Each SDK is the loop and the tool type and nothing else: `@novox/mesh-sdk/stdio` (serveStdio, and serveRegisteredOverStdio for a bundle that already registers the in-process way), python/, go/, rust/ and c/ beside it, each with an example answering `greet` and the seat verb `node-lamp.on`. Skeletons, by the operator's direction: the bare minimum one bundle per language needs to be built and answer, proven here by each example answering tools/list and tools/call on stdio.
109 lines
3.7 KiB
Go
109 lines
3.7 KiB
Go
// Package stdio is the Novox Mesh SDK for Go — the skeleton (novox/hq ADR 0187).
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//
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// A tools bundle is a process the node's runtime launches and speaks MCP over stdio to:
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// `initialize`, `tools/list` once, `tools/call` per call, newline-framed JSON-RPC on stdin and
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// stdout. This package is the loop, so a bundle writes its tools and nothing else. A tool named
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// `<seat>.<verb>` is the module's implementation of that seat's verb; any other name is the
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// module's own.
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//
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// No transport here: the bus, the subjects and the memberships are the runtime's (ADR 0039, 0175).
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// stdout is the protocol; log to stderr.
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package stdio
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import (
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"bufio"
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"encoding/json"
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"fmt"
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"io"
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"os"
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)
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// Protocol is the MCP version this speaks; the runtime says the same.
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const Protocol = "2025-03-26"
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// Tool is one tool a bundle serves.
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type Tool struct {
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Name string
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Description string
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// Input is the JSON schema of the arguments; nil is a tool that takes nothing.
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Input map[string]any
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Run func(args map[string]any) (any, error)
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}
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type request struct {
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ID *json.RawMessage `json:"id"`
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Method string `json:"method"`
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Params struct {
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Name string `json:"name"`
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Arguments map[string]any `json:"arguments"`
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} `json:"params"`
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}
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// Serve answers the runtime on stdin and stdout until stdin closes.
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func Serve(name string, tools []Tool) error {
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return ServeOn(name, tools, os.Stdin, os.Stdout)
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}
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// ServeOn is Serve over any pair of streams, for a test.
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func ServeOn(name string, tools []Tool, in io.Reader, out io.Writer) error {
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byName := map[string]Tool{}
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for _, t := range tools {
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byName[t.Name] = t
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}
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enc := json.NewEncoder(out)
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say := func(m map[string]any) { m["jsonrpc"] = "2.0"; _ = enc.Encode(m) }
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scanner := bufio.NewScanner(in)
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scanner.Buffer(make([]byte, 1<<20), 1<<24)
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for scanner.Scan() {
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var req request
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if err := json.Unmarshal(scanner.Bytes(), &req); err != nil {
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continue
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}
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id := any(nil)
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if req.ID != nil {
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id = *req.ID
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}
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switch req.Method {
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case "initialize":
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say(map[string]any{"id": id, "result": map[string]any{"protocolVersion": Protocol,
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"capabilities": map[string]any{"tools": map[string]any{}},
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"serverInfo": map[string]any{"name": name, "version": "1"}}})
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case "notifications/initialized":
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case "ping":
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if id != nil {
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say(map[string]any{"id": id, "result": map[string]any{}})
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}
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case "tools/list":
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listed := make([]map[string]any, 0, len(tools))
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for _, t := range tools {
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schema := t.Input
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if schema == nil {
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schema = map[string]any{"type": "object", "properties": map[string]any{}}
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} else if _, isSchema := schema["type"]; !isSchema {
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schema = map[string]any{"type": "object", "properties": schema}
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}
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listed = append(listed, map[string]any{"name": t.Name, "description": t.Description, "inputSchema": schema})
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}
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say(map[string]any{"id": id, "result": map[string]any{"tools": listed}})
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case "tools/call":
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t, ok := byName[req.Params.Name]
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if !ok {
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say(map[string]any{"id": id, "error": map[string]any{"code": -32602, "message": fmt.Sprintf("%s has no tool %s", name, req.Params.Name)}})
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continue
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}
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result, err := t.Run(req.Params.Arguments)
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if err != nil {
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say(map[string]any{"id": id, "result": map[string]any{"content": []map[string]any{{"type": "text", "text": err.Error()}}, "isError": true}})
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continue
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}
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text, _ := json.Marshal(result)
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say(map[string]any{"id": id, "result": map[string]any{"content": []map[string]any{{"type": "text", "text": string(text)}}}})
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default:
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if id != nil {
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say(map[string]any{"id": id, "error": map[string]any{"code": -32601, "message": "no " + req.Method}})
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}
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}
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}
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return scanner.Err()
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}
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