fix(hooks,db,mcp,worker): add type safety and error handling (#21)

- [x] Add type checking and error handling for JSON type assertions in user-prompt hook
- [x] Add error handling for session update query in CreateSDKSession
- [x] Update MCP tool description to reference sqlite-vec instead of ChromaDB
- [x] Fix MinConfidence sentinel value check from 0 to -1
- [x] Pass project parameter to vector search filter in handleSearchByPrompt
- [x] Return empty map instead of nil for successful responses without JSON body

cmd/hooks/user-prompt/main.go

@@ -94,8 +94,18 @@ func handleUserPrompt(ctx *hooks.HookContext, input *Input) (string, error) {
 		return "", nil
 	}
 
-	sessionID := int64(result["sessionDbId"].(float64))
-	promptNumber := int(result["promptNumber"].(float64))
+	// Safely extract session ID and prompt number with type checking
+	sessionDbIdRaw, ok := result["sessionDbId"].(float64)
+	if !ok {
+		return "", fmt.Errorf("invalid or missing sessionDbId in response")
+	}
+	sessionID := int64(sessionDbIdRaw)
+
+	promptNumberRaw, ok := result["promptNumber"].(float64)
+	if !ok {
+		return "", fmt.Errorf("invalid or missing promptNumber in response")
+	}
+	promptNumber := int(promptNumberRaw)
 
 	fmt.Fprintf(os.Stderr, "[user-prompt] Session %d, prompt #%d\n", sessionID, promptNumber)
 

internal/db/gorm/session_store.go

@@ -4,6 +4,7 @@ package gorm
 import (
 	"context"
 	"database/sql"
+	"fmt"
 	"time"
 
 	"gorm.io/gorm"
@@ -67,10 +68,12 @@ func (s *SessionStore) CreateSDKSession(ctx context.Context, claudeSessionID, pr
 			if userPrompt != "" {
 				updates["user_prompt"] = userPrompt
 			}
-			s.db.WithContext(ctx).
+			if err := s.db.WithContext(ctx).
 				Model(&SDKSession{}).
 				Where("claude_session_id = ?", claudeSessionID).
-				Updates(updates)
+				Updates(updates).Error; err != nil {
+				return 0, fmt.Errorf("failed to update session: %w", err)
+			}
 		}
 
 		// Fetch existing session

internal/mcp/server.go

@@ -164,7 +164,7 @@ func (s *Server) handleToolsList(req *Request) *Response {
 	tools := []Tool{
 		{
 			Name:        "search",
-			Description: "Unified search across all memory types (observations, sessions, and user prompts) using vector-first semantic search (ChromaDB).",
+			Description: "Unified search across all memory types (observations, sessions, and user prompts) using vector-first semantic search (sqlite-vec).",
 			InputSchema: map[string]any{
 				"type": "object",
 				"properties": map[string]any{
@@ -599,7 +599,8 @@ func (s *Server) handleFindRelatedObservations(ctx context.Context, args json.Ra
 		return "", fmt.Errorf("id is required")
 	}
 
-	if params.MinConfidence == 0 {
+	// Use -1 as sentinel for "not provided" since 0.0 is a valid threshold
+	if params.MinConfidence < 0 {
 		params.MinConfidence = 0.5
 	}
 

internal/worker/handlers.go

@@ -774,7 +774,7 @@ func (s *Service) handleSearchByPrompt(w http.ResponseWriter, r *http.Request) {
 
 	// Try vector search first if available
 	if s.vectorClient != nil && s.vectorClient.IsConnected() {
-		where := sqlitevec.BuildWhereFilter(sqlitevec.DocTypeObservation, "")
+		where := sqlitevec.BuildWhereFilter(sqlitevec.DocTypeObservation, project)
 
 		// Search with each expanded query and merge results
 		allVectorResults := make([]sqlitevec.QueryResult, 0)

pkg/hooks/worker.go

@@ -251,8 +251,8 @@ func POST(port int, path string, body interface{}) (map[string]interface{}, erro
 
 	var result map[string]interface{}
 	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
-		// Not all endpoints return JSON
-		return nil, nil
+		// Not all endpoints return JSON body - return empty map for success with no body
+		return map[string]interface{}{}, nil
 	}
 
 	return result, nil