feat(ingestion): add query and write HTTP handlers

Implements POST /query (BM25 search via internal/search) and POST /write
(raw file persistence to brain/raw/) as an api.Handler struct. Filename
is auto-generated when absent.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ingestion/internal/api/handler.go

@@ -0,0 +1,96 @@
+// ingestion/internal/api/handler.go
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/search"
+)
+
+// Handler serves the ingestion HTTP API.
+type Handler struct {
+	brainDir string
+	logger   *slog.Logger
+}
+
+// NewHandler constructs a Handler. brainDir is the absolute path to brain/.
+func NewHandler(brainDir string, logger *slog.Logger) *Handler {
+	return &Handler{brainDir: brainDir, logger: logger}
+}
+
+type queryRequest struct {
+	Query  string `json:"query"`
+	Domain string `json:"domain,omitempty"`
+	Limit  int    `json:"limit,omitempty"`
+}
+
+type writeRequest struct {
+	Content  string `json:"content"`
+	Filename string `json:"filename,omitempty"`
+}
+
+// Query handles POST /query — full-text search across the brain wiki.
+func (h *Handler) Query(w http.ResponseWriter, r *http.Request) {
+	var req queryRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		http.Error(w, "invalid JSON", http.StatusBadRequest)
+		return
+	}
+	if req.Limit == 0 {
+		req.Limit = 5
+	}
+
+	results, err := search.Query(h.brainDir, req.Query, req.Limit)
+	if err != nil {
+		h.logger.Error("query failed", "err", err)
+		http.Error(w, "search error", http.StatusInternalServerError)
+		return
+	}
+
+	writeJSON(w, map[string]any{"results": results})
+}
+
+// Write handles POST /write — write raw content to brain/raw/.
+func (h *Handler) Write(w http.ResponseWriter, r *http.Request) {
+	var req writeRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		http.Error(w, "invalid JSON", http.StatusBadRequest)
+		return
+	}
+	if req.Content == "" {
+		http.Error(w, "content is required", http.StatusBadRequest)
+		return
+	}
+
+	filename := req.Filename
+	if filename == "" {
+		filename = fmt.Sprintf("%s-auto.md", time.Now().UTC().Format("2006-01-02-150405"))
+	}
+
+	rawDir := filepath.Join(h.brainDir, "raw")
+	if err := os.MkdirAll(rawDir, 0o755); err != nil {
+		http.Error(w, "failed to create raw dir", http.StatusInternalServerError)
+		return
+	}
+
+	dest := filepath.Join(rawDir, filepath.Base(filename))
+	if err := os.WriteFile(dest, []byte(req.Content), 0o644); err != nil {
+		h.logger.Error("write failed", "err", err)
+		http.Error(w, "write error", http.StatusInternalServerError)
+		return
+	}
+
+	rel, _ := filepath.Rel(h.brainDir, dest)
+	writeJSON(w, map[string]string{"path": filepath.ToSlash(rel)})
+}
+
+func writeJSON(w http.ResponseWriter, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(v) //nolint:errcheck
+}