feat: implement file referencing with @filename autocomplete in chat input (#118)

apps/backend/internal/agentctl/server/api/server.go

@@ -82,6 +82,7 @@ func (s *Server) setupRoutes() {
 		// Workspace file operations (simple HTTP)
 		api.GET("/workspace/tree", s.handleFileTree)
 		api.GET("/workspace/file/content", s.handleFileContent)
+		api.GET("/workspace/search", s.handleFileSearch)
 
 		// Shell access (HTTP endpoints only - streaming is via /workspace/stream)
 		api.GET("/shell/status", s.handleShellStatus)

apps/backend/internal/agentctl/server/api/workspace.go

@@ -151,6 +151,21 @@ func (s *Server) handleFileContent(c *gin.Context) {
 	c.JSON(200, types.FileContentResponse{Path: path, Content: content, Size: size})
 }
 
+// handleFileSearch handles file search requests via HTTP GET
+func (s *Server) handleFileSearch(c *gin.Context) {
+	query := c.Query("q")
+	limit := 20
+	if l := c.Query("limit"); l != "" {
+		if parsed := mustParseInt(l); parsed > 0 {
+			limit = parsed
+		}
+	}
+
+	files := s.procMgr.GetWorkspaceTracker().SearchFiles(query, limit)
+
+	c.JSON(200, types.FileSearchResponse{Files: files})
+}
+
 // mustParseInt parses a string to int, returns 0 on error
 func mustParseInt(s string) int {
 	var n int

apps/backend/internal/agentctl/server/process/workspace_tracker.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -1183,3 +1184,65 @@ func (wt *WorkspaceTracker) GetFileContent(reqPath string) (string, int64, error
 
 	return string(content), info.Size(), nil
 }
+
+// scoredMatch holds a file path and its match score for sorting
+type scoredMatch struct {
+	path  string
+	score int
+}
+
+// SearchFiles searches for files matching the query string.
+// It uses fuzzy matching with scoring based on how well the query matches.
+func (wt *WorkspaceTracker) SearchFiles(query string, limit int) []string {
+	if query == "" {
+		return []string{}
+	}
+	if limit <= 0 {
+		limit = 20
+	}
+
+	query = strings.ToLower(query)
+	var matches []scoredMatch
+
+	wt.mu.RLock()
+	files := wt.currentFiles.Files
+	wt.mu.RUnlock()
+
+	for _, file := range files {
+		path := file.Path
+		lowerPath := strings.ToLower(path)
+		name := filepath.Base(lowerPath)
+
+		score := 0
+		if name == query {
+			score = 100 // Exact filename match
+		} else if strings.HasPrefix(name, query) {
+			score = 75 // Filename starts with query
+		} else if strings.Contains(name, query) {
+			score = 50 // Filename contains query
+		} else if strings.Contains(lowerPath, query) {
+			score = 25 // Path contains query
+		}
+
+		if score > 0 {
+			matches = append(matches, scoredMatch{path: path, score: score})
+		}
+	}
+
+	// Sort by score descending
+	sort.Slice(matches, func(i, j int) bool {
+		if matches[i].score != matches[j].score {
+			return matches[i].score > matches[j].score
+		}
+		// Secondary sort by path length (shorter paths first)
+		return len(matches[i].path) < len(matches[j].path)
+	})
+
+	// Return top limit results
+	result := make([]string, 0, limit)
+	for i := 0; i < len(matches) && i < limit; i++ {
+		result = append(result, matches[i].path)
+	}
+
+	return result
+}