feat(ingestion): mount MCP handler at POST /mcp

The ingestion server now exposes both REST and MCP on the same port
(3300). MCP shares brainDir, pipeline config, and LLM client with the
REST handlers — single source of process state.

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

ingestion/cmd/server/main.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/llm"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/mcp"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/watcher"
 )
@@ -54,6 +55,8 @@ func main() {
 
 	h := api.NewHandler(brainDir, logger, pipelineCfg)
 
+	mcpSrv := mcp.NewServer(brainDir, &pipelineCfg, llmClient.Complete)
+
 	ctx := context.Background()
 	if watchInterval > 0 {
 		watcher.Start(ctx, watcher.Config{
@@ -70,6 +73,7 @@ func main() {
 	mux.HandleFunc("POST /ingest-path", h.IngestPath)
 	mux.HandleFunc("POST /ingest-raw", h.IngestRaw)
 	mux.HandleFunc("POST /backfill-refs", h.BackfillRefs)
+	mux.Handle("POST /mcp", mcpSrv)
 
 	addr := ":" + port
 	watchIntervalLog := "disabled"
@@ -83,6 +87,7 @@ func main() {
 		"llm_model", llmModel,
 		"chunk_size", chunkSize,
 		"watch_interval", watchIntervalLog,
+		"mcp_enabled", true,
 	)
 	if err := http.ListenAndServe(addr, mux); err != nil {
 		logger.Error("server stopped", "err", err)

ingestion/internal/mcp/integration_test.go

@@ -0,0 +1,35 @@
+package mcp_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/mcp"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMCPMountedHandler(t *testing.T) {
+	srv := mcp.NewServer(t.TempDir(), nil, nil)
+	mux := http.NewServeMux()
+	mux.Handle("POST /mcp", srv)
+
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	body, err := json.Marshal(map[string]any{
+		"jsonrpc": "2.0", "id": 1, "method": "tools/list",
+	})
+	require.NoError(t, err)
+	resp, err := http.Post(ts.URL+"/mcp", "application/json", bytes.NewReader(body))
+	require.NoError(t, err)
+	defer resp.Body.Close()
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+
+	out, _ := io.ReadAll(resp.Body)
+	assert.Contains(t, string(out), `"brain_query"`)
+}