feat(ingestion): add MCP server skeleton with tools/list

Adds an MCP HTTP handler under ingestion/internal/mcp. Implements
initialize, tools/list, and the JSON-RPC notification skip from prior
work. Tool dispatch is stubbed (returns unknown-tool error) and will be
filled in by subsequent tasks.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ingestion/internal/mcp/handlers.go

@@ -0,0 +1,75 @@
+package mcp
+
+import "encoding/json"
+
+// tools returns the tool descriptors. Handler bodies for each tool are filled
+// in subsequent tasks; this file currently only provides the descriptors.
+func (s *Server) tools() []map[string]any {
+	str := func(desc string) map[string]any {
+		return map[string]any{"type": "string", "description": desc}
+	}
+	int_ := func(desc string) map[string]any {
+		return map[string]any{"type": "integer", "description": desc}
+	}
+	schema := func(required []string, props map[string]any) json.RawMessage {
+		b, _ := json.Marshal(map[string]any{
+			"type": "object", "required": required, "properties": props,
+		})
+		return b
+	}
+
+	return []map[string]any{
+		{
+			"name":        "brain_query",
+			"description": "BM25 full-text search across brain/knowledge/ and brain/wiki/ markdown files.",
+			"inputSchema": schema([]string{"query"}, map[string]any{
+				"query": str("search terms"),
+				"limit": int_("max results, default 5"),
+			}),
+		},
+		{
+			"name":        "brain_write",
+			"description": "Write a raw knowledge note to brain/knowledge/.",
+			"inputSchema": schema([]string{"content"}, map[string]any{
+				"content":  str("markdown content"),
+				"filename": str("optional filename"),
+				"type":     str("optional frontmatter type"),
+				"domain":   str("optional frontmatter domain"),
+			}),
+		},
+		{
+			"name":        "brain_ingest_raw",
+			"description": "Ingest pre-structured pages into the brain wiki, bypassing the LLM extraction step.",
+			"inputSchema": schema([]string{"source", "pages"}, map[string]any{
+				"source":  str("source name"),
+				"pages":   map[string]any{"type": "array"},
+				"dry_run": map[string]any{"type": "boolean"},
+			}),
+		},
+		{
+			"name":        "brain_ingest",
+			"description": "Ingest content into the brain wiki via the LLM extraction pipeline.",
+			"inputSchema": schema([]string{}, map[string]any{
+				"content": str("raw content; required when path is empty"),
+				"source":  str("source name; required when path is empty"),
+				"path":    str("file path; mutually exclusive with content+source"),
+				"dry_run": map[string]any{"type": "boolean"},
+			}),
+		},
+		{
+			"name":        "session_log",
+			"description": "Append a structured entry to brain/sessions/<session_id>.jsonl.",
+			"inputSchema": schema([]string{"session_id"}, map[string]any{
+				"session_id":   str("session identifier"),
+				"skill":        str("skill name"),
+				"phase":        str("phase within the skill"),
+				"project_root": str("absolute project root"),
+				"final_status": str("ok | error | skipped"),
+				"file_path":    str("optional file produced"),
+				"model_used":   str("optional model identifier"),
+				"duration_ms":  int_("optional duration in ms"),
+				"message":      str("optional free-text"),
+			}),
+		},
+	}
+}

ingestion/internal/mcp/server.go

@@ -0,0 +1,119 @@
+// Package mcp implements an MCP HTTP handler for the ingestion service.
+// Exposed tools: brain_query, brain_write, brain_ingest, brain_ingest_raw, session_log.
+package mcp
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
+)
+
+type request struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      any             `json:"id"`
+	Method  string          `json:"method"`
+	Params  json.RawMessage `json:"params"`
+}
+
+type response struct {
+	JSONRPC string    `json:"jsonrpc"`
+	ID      any       `json:"id,omitempty"`
+	Result  any       `json:"result,omitempty"`
+	Error   *rpcError `json:"error,omitempty"`
+}
+
+type rpcError struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
+
+// Server handles MCP JSON-RPC over HTTP for the ingestion service.
+type Server struct {
+	brainDir string
+	pipeline pipeline.Config
+	llm      pipeline.CompleteFunc
+}
+
+// NewServer constructs a Server bound to brainDir. pipelineCfg supplies the
+// LLM-backed pipeline; llm may be nil for non-LLM tools only.
+func NewServer(brainDir string, pipelineCfg *pipeline.Config, llm pipeline.CompleteFunc) *Server {
+	cfg := pipeline.Config{}
+	if pipelineCfg != nil {
+		cfg = *pipelineCfg
+	}
+	return &Server{brainDir: brainDir, pipeline: cfg, llm: llm}
+}
+
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	var req request
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, nil, -32700, "parse error")
+		return
+	}
+
+	// JSON-RPC 2.0 notifications (no id) must not receive a response.
+	if req.ID == nil {
+		return
+	}
+
+	var result any
+	var rpcErr *rpcError
+
+	switch req.Method {
+	case "initialize":
+		result = map[string]any{
+			"protocolVersion": "2024-11-05",
+			"capabilities":    map[string]any{"tools": map[string]any{}},
+			"serverInfo":      map[string]any{"name": "ingestion-brain", "version": "0.1.0"},
+		}
+
+	case "tools/list":
+		result = map[string]any{"tools": s.tools()}
+
+	case "tools/call":
+		var p struct {
+			Name      string          `json:"name"`
+			Arguments json.RawMessage `json:"arguments"`
+		}
+		if err := json.Unmarshal(req.Params, &p); err != nil {
+			rpcErr = &rpcError{Code: -32602, Message: "invalid params"}
+			break
+		}
+		out, err := s.handleCall(r.Context(), p.Name, p.Arguments)
+		if err != nil {
+			rpcErr = &rpcError{Code: -32000, Message: err.Error()}
+			break
+		}
+		result = map[string]any{
+			"content": []map[string]any{{"type": "text", "text": string(out)}},
+		}
+
+	default:
+		rpcErr = &rpcError{Code: -32601, Message: "method not found: " + req.Method}
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(response{
+		JSONRPC: "2.0",
+		ID:      req.ID,
+		Result:  result,
+		Error:   rpcErr,
+	})
+}
+
+func writeError(w http.ResponseWriter, id any, code int, msg string) {
+	w.Header().Set("Content-Type", "application/json")
+	_ = json.NewEncoder(w).Encode(response{
+		JSONRPC: "2.0",
+		ID:      id,
+		Error:   &rpcError{Code: code, Message: msg},
+	})
+}
+
+// handleCall dispatches a tools/call. Stub for Task 1; expanded in later tasks.
+func (s *Server) handleCall(ctx context.Context, name string, args json.RawMessage) (json.RawMessage, error) {
+	return nil, fmt.Errorf("unknown tool: %s", name)
+}

ingestion/internal/mcp/server_test.go

@@ -0,0 +1,91 @@
+package mcp_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/mcp"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func body(t *testing.T, v any) *bytes.Buffer {
+	t.Helper()
+	b, err := json.Marshal(v)
+	require.NoError(t, err)
+	return bytes.NewBuffer(b)
+}
+
+func TestServerInitialize(t *testing.T) {
+	srv := mcp.NewServer(t.TempDir(), nil, nil)
+
+	req := httptest.NewRequest(http.MethodPost, "/mcp", body(t, map[string]any{
+		"jsonrpc": "2.0", "id": 1, "method": "initialize",
+		"params": map[string]any{},
+	}))
+	rr := httptest.NewRecorder()
+	srv.ServeHTTP(rr, req)
+
+	assert.Equal(t, http.StatusOK, rr.Code)
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rr.Body.Bytes(), &resp))
+	result := resp["result"].(map[string]any)
+	assert.Equal(t, "2024-11-05", result["protocolVersion"])
+}
+
+func TestServerToolsList(t *testing.T) {
+	srv := mcp.NewServer(t.TempDir(), nil, nil)
+
+	req := httptest.NewRequest(http.MethodPost, "/mcp", body(t, map[string]any{
+		"jsonrpc": "2.0", "id": 2, "method": "tools/list",
+	}))
+	rr := httptest.NewRecorder()
+	srv.ServeHTTP(rr, req)
+
+	assert.Equal(t, http.StatusOK, rr.Code)
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rr.Body.Bytes(), &resp))
+	tools := resp["result"].(map[string]any)["tools"].([]any)
+	names := make([]string, 0, len(tools))
+	for _, t := range tools {
+		names = append(names, t.(map[string]any)["name"].(string))
+	}
+	assert.ElementsMatch(t, []string{
+		"brain_query", "brain_write", "brain_ingest_raw", "brain_ingest", "session_log",
+	}, names)
+}
+
+func TestServerNotificationGetsNoBody(t *testing.T) {
+	srv := mcp.NewServer(t.TempDir(), nil, nil)
+
+	req := httptest.NewRequest(http.MethodPost, "/mcp", body(t, map[string]any{
+		"jsonrpc": "2.0", "method": "notifications/initialized",
+	}))
+	rr := httptest.NewRecorder()
+	srv.ServeHTTP(rr, req)
+
+	assert.Equal(t, http.StatusOK, rr.Code)
+	assert.Empty(t, strings.TrimSpace(rr.Body.String()))
+}
+
+func TestServerUnknownMethodReturnsError(t *testing.T) {
+	srv := mcp.NewServer(t.TempDir(), nil, nil)
+
+	req := httptest.NewRequest(http.MethodPost, "/mcp", body(t, map[string]any{
+		"jsonrpc": "2.0", "id": 3, "method": "unknown/method",
+	}))
+	rr := httptest.NewRecorder()
+	srv.ServeHTTP(rr, req)
+
+	assert.Equal(t, http.StatusOK, rr.Code)
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rr.Body.Bytes(), &resp))
+	require.NotNil(t, resp["error"])
+	errObj := resp["error"].(map[string]any)
+	assert.Equal(t, float64(-32601), errObj["code"])
+	assert.Contains(t, errObj["message"].(string), "unknown/method")
+}