diff --git a/apps/backend/internal/editors/controller/controller.go b/apps/backend/internal/editors/controller/controller.go
index d187042815..f886739e11 100644
--- a/apps/backend/internal/editors/controller/controller.go
+++ b/apps/backend/internal/editors/controller/controller.go
@@ -63,6 +63,7 @@ func (c *Controller) OpenSessionEditor(ctx context.Context, sessionID string, re
 		FilePath:   req.FilePath,
 		Line:       req.Line,
 		Column:     req.Column,
+		WorktreeID: req.WorktreeID,
 	})
 	if err != nil {
 		return dto.OpenEditorResponse{}, err
@@ -70,8 +71,8 @@ func (c *Controller) OpenSessionEditor(ctx context.Context, sessionID string, re
 	return dto.OpenEditorResponse{URL: url}, nil
 }
 
-func (c *Controller) OpenFolder(ctx context.Context, sessionID string) (dto.OpenFolderResponse, error) {
-	if err := c.service.OpenFolder(ctx, sessionID); err != nil {
+func (c *Controller) OpenFolder(ctx context.Context, sessionID string, req dto.OpenFolderRequest) (dto.OpenFolderResponse, error) {
+	if err := c.service.OpenFolder(ctx, sessionID, req.WorktreeID); err != nil {
 		return dto.OpenFolderResponse{Success: false}, err
 	}
 	return dto.OpenFolderResponse{Success: true}, nil
diff --git a/apps/backend/internal/editors/dto/dto.go b/apps/backend/internal/editors/dto/dto.go
index d95e858cb1..2de747bb05 100644
--- a/apps/backend/internal/editors/dto/dto.go
+++ b/apps/backend/internal/editors/dto/dto.go
@@ -31,6 +31,9 @@ type OpenEditorRequest struct {
 	FilePath   string `json:"file_path,omitempty"`
 	Line       int    `json:"line,omitempty"`
 	Column     int    `json:"column,omitempty"`
+	// WorktreeID selects which of the session's worktrees to open
+	// (multi-repo sessions); empty falls back to the first worktree.
+	WorktreeID string `json:"worktree_id,omitempty"`
 }
 
 type OpenEditorResponse struct {
@@ -70,6 +73,12 @@ type UpdateEditorRequest struct {
 	Enabled *bool           `json:"enabled,omitempty"`
 }
 
+type OpenFolderRequest struct {
+	// WorktreeID selects which of the session's worktrees to open
+	// (multi-repo sessions); empty falls back to the first worktree.
+	WorktreeID string `json:"worktree_id,omitempty"`
+}
+
 type OpenFolderResponse struct {
 	Success bool `json:"success"`
 }
diff --git a/apps/backend/internal/editors/handlers/handlers.go b/apps/backend/internal/editors/handlers/handlers.go
index 2ccb98516e..c3326ecb2d 100644
--- a/apps/backend/internal/editors/handlers/handlers.go
+++ b/apps/backend/internal/editors/handlers/handlers.go
@@ -1,6 +1,8 @@
 package handlers
 
 import (
+	"errors"
+	"io"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
@@ -9,8 +11,24 @@ import (
 	"github.com/kandev/kandev/internal/common/logger"
 	"github.com/kandev/kandev/internal/editors/controller"
 	"github.com/kandev/kandev/internal/editors/dto"
+	"github.com/kandev/kandev/internal/editors/service"
 )
 
+// serviceErrorStatus maps known service errors to HTTP status codes so
+// client mistakes (bad worktree_id, unknown editor) don't surface as 500s.
+func serviceErrorStatus(err error) int {
+	switch {
+	case errors.Is(err, service.ErrEditorNotFound), errors.Is(err, service.ErrWorkspaceNotFound):
+		return http.StatusNotFound
+	case errors.Is(err, service.ErrEditorConfigInvalid):
+		return http.StatusBadRequest
+	case errors.Is(err, service.ErrEditorUnavailable):
+		return http.StatusConflict
+	default:
+		return http.StatusInternalServerError
+	}
+}
+
 type Handlers struct {
 	controller *controller.Controller
 	logger     *logger.Logger
@@ -53,7 +71,7 @@ func (h *Handlers) httpOpenSessionEditor(c *gin.Context) {
 	resp, err := h.controller.OpenSessionEditor(c.Request.Context(), c.Param("id"), req)
 	if err != nil {
 		h.logger.Error("failed to open editor", zap.Error(err))
-		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to open editor"})
+		c.JSON(serviceErrorStatus(err), gin.H{"error": "failed to open editor"})
 		return
 	}
 	c.JSON(http.StatusOK, resp)
@@ -99,10 +117,18 @@ func (h *Handlers) httpDeleteEditor(c *gin.Context) {
 }
 
 func (h *Handlers) httpOpenFolder(c *gin.Context) {
-	resp, err := h.controller.OpenFolder(c.Request.Context(), c.Param("id"))
+	var req dto.OpenFolderRequest
+	// The body is optional for backward compatibility; an empty body decodes
+	// as EOF and keeps the zero value. Checking ContentLength instead would
+	// silently drop the payload of chunked requests (ContentLength == -1).
+	if err := c.ShouldBindJSON(&req); err != nil && !errors.Is(err, io.EOF) {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid payload"})
+		return
+	}
+	resp, err := h.controller.OpenFolder(c.Request.Context(), c.Param("id"), req)
 	if err != nil {
 		h.logger.Error("failed to open folder", zap.Error(err))
-		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to open folder"})
+		c.JSON(serviceErrorStatus(err), gin.H{"error": "failed to open folder"})
 		return
 	}
 	c.JSON(http.StatusOK, resp)
diff --git a/apps/backend/internal/editors/handlers/handlers_test.go b/apps/backend/internal/editors/handlers/handlers_test.go
new file mode 100644
index 0000000000..40b0c376a3
--- /dev/null
+++ b/apps/backend/internal/editors/handlers/handlers_test.go
@@ -0,0 +1,32 @@
+package handlers
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/kandev/kandev/internal/editors/service"
+)
+
+func TestServiceErrorStatus(t *testing.T) {
+	tests := []struct {
+		err      error
+		expected int
+	}{
+		{service.ErrWorkspaceNotFound, http.StatusNotFound},
+		{service.ErrEditorNotFound, http.StatusNotFound},
+		{service.ErrEditorConfigInvalid, http.StatusBadRequest},
+		{service.ErrEditorUnavailable, http.StatusConflict},
+		{fmt.Errorf("wrapped: %w", service.ErrWorkspaceNotFound), http.StatusNotFound},
+		{errors.New("something else"), http.StatusInternalServerError},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.err.Error(), func(t *testing.T) {
+			if got := serviceErrorStatus(tt.err); got != tt.expected {
+				t.Errorf("serviceErrorStatus(%v) = %d, want %d", tt.err, got, tt.expected)
+			}
+		})
+	}
+}
diff --git a/apps/backend/internal/editors/service/service.go b/apps/backend/internal/editors/service/service.go
index e7a65f2ee9..c2f2cebd05 100644
--- a/apps/backend/internal/editors/service/service.go
+++ b/apps/backend/internal/editors/service/service.go
@@ -72,6 +72,7 @@ type OpenEditorInput struct {
 	FilePath   string
 	Line       int
 	Column     int
+	WorktreeID string
 }
 
 func (s *Service) OpenEditor(ctx context.Context, input OpenEditorInput) (string, error) {
@@ -82,7 +83,7 @@ func (s *Service) OpenEditor(ctx context.Context, input OpenEditorInput) (string
 	if err != nil {
 		return "", err
 	}
-	worktreePath, err := s.resolveSessionPath(ctx, session)
+	worktreePath, err := s.resolveSessionPath(ctx, session, input.WorktreeID)
 	if err != nil {
 		return "", err
 	}
@@ -183,7 +184,7 @@ func openBuiltinEditor(editor *models.Editor, absPath string, line, column int)
 	return "", nil
 }
 
-func (s *Service) OpenFolder(ctx context.Context, sessionID string) error {
+func (s *Service) OpenFolder(ctx context.Context, sessionID, worktreeID string) error {
 	if sessionID == "" {
 		return ErrEditorConfigInvalid
 	}
@@ -191,7 +192,7 @@ func (s *Service) OpenFolder(ctx context.Context, sessionID string) error {
 	if err != nil {
 		return err
 	}
-	worktreePath, err := s.resolveSessionPath(ctx, session)
+	worktreePath, err := s.resolveSessionPath(ctx, session, worktreeID)
 	if err != nil {
 		return err
 	}
@@ -250,10 +251,13 @@ func (s *Service) resolveEditor(ctx context.Context, editorID, editorType, fallb
 	return editor, nil
 }
 
-func (s *Service) resolveSessionPath(ctx context.Context, session *taskmodels.TaskSession) (string, error) {
+func (s *Service) resolveSessionPath(ctx context.Context, session *taskmodels.TaskSession, worktreeID string) (string, error) {
 	if session == nil {
 		return "", ErrWorkspaceNotFound
 	}
+	if worktreeID != "" {
+		return findSessionWorktreePath(session, worktreeID)
+	}
 	if len(session.Worktrees) > 0 && session.Worktrees[0].WorktreePath != "" {
 		return session.Worktrees[0].WorktreePath, nil
 	}
@@ -269,6 +273,22 @@ func (s *Service) resolveSessionPath(ctx context.Context, session *taskmodels.Ta
 	return "", ErrWorkspaceNotFound
 }
 
+// findSessionWorktreePath returns the path of the session worktree matching
+// worktreeID. It matches both the worktree ID and the session-worktree
+// association ID, since clients may hold either.
+func findSessionWorktreePath(session *taskmodels.TaskSession, worktreeID string) (string, error) {
+	for _, worktree := range session.Worktrees {
+		if worktree == nil || (worktree.WorktreeID != worktreeID && worktree.ID != worktreeID) {
+			continue
+		}
+		if worktree.WorktreePath == "" {
+			return "", ErrWorkspaceNotFound
+		}
+		return worktree.WorktreePath, nil
+	}
+	return "", ErrWorkspaceNotFound
+}
+
 func (s *Service) resolveFilePath(worktreePath, filePath string) (string, error) {
 	if worktreePath == "" {
 		return "", ErrWorkspaceNotFound
diff --git a/apps/backend/internal/editors/service/service_test.go b/apps/backend/internal/editors/service/service_test.go
index 6f495f3073..f32aa950a5 100644
--- a/apps/backend/internal/editors/service/service_test.go
+++ b/apps/backend/internal/editors/service/service_test.go
@@ -9,7 +9,7 @@ import (
 
 func TestOpenFolder_EmptySessionID(t *testing.T) {
 	svc := &Service{}
-	err := svc.OpenFolder(context.Background(), "")
+	err := svc.OpenFolder(context.Background(), "", "")
 	if err != ErrEditorConfigInvalid {
 		t.Errorf("expected ErrEditorConfigInvalid, got %v", err)
 	}
@@ -17,7 +17,7 @@ func TestOpenFolder_EmptySessionID(t *testing.T) {
 
 func TestResolveSessionPath_NilSession(t *testing.T) {
 	svc := &Service{}
-	_, err := svc.resolveSessionPath(context.Background(), nil)
+	_, err := svc.resolveSessionPath(context.Background(), nil, "")
 	if err != ErrWorkspaceNotFound {
 		t.Errorf("expected ErrWorkspaceNotFound, got %v", err)
 	}
@@ -31,7 +31,7 @@ func TestResolveSessionPath_WithWorktree(t *testing.T) {
 			{WorktreePath: "/path/to/worktree"},
 		},
 	}
-	path, err := svc.resolveSessionPath(context.Background(), session)
+	path, err := svc.resolveSessionPath(context.Background(), session, "")
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -48,7 +48,57 @@ func TestResolveSessionPath_EmptyWorktreePath(t *testing.T) {
 			{WorktreePath: ""},
 		},
 	}
-	_, err := svc.resolveSessionPath(context.Background(), session)
+	_, err := svc.resolveSessionPath(context.Background(), session, "")
+	if err != ErrWorkspaceNotFound {
+		t.Errorf("expected ErrWorkspaceNotFound, got %v", err)
+	}
+}
+
+func TestResolveSessionPath_SelectsWorktreeByID(t *testing.T) {
+	svc := &Service{}
+	session := &taskmodels.TaskSession{
+		ID: "session-1",
+		Worktrees: []*taskmodels.TaskSessionWorktree{
+			{ID: "assoc-1", WorktreeID: "wt-1", WorktreePath: "/path/to/repo-a"},
+			{ID: "assoc-2", WorktreeID: "wt-2", WorktreePath: "/path/to/repo-b"},
+		},
+	}
+
+	tests := []struct {
+		name       string
+		worktreeID string
+		expected   string
+		expectErr  error
+	}{
+		{name: "by worktree id", worktreeID: "wt-2", expected: "/path/to/repo-b"},
+		{name: "by association id", worktreeID: "assoc-2", expected: "/path/to/repo-b"},
+		{name: "empty falls back to first", worktreeID: "", expected: "/path/to/repo-a"},
+		{name: "unknown id", worktreeID: "wt-missing", expectErr: ErrWorkspaceNotFound},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			path, err := svc.resolveSessionPath(context.Background(), session, tt.worktreeID)
+			if err != tt.expectErr {
+				t.Fatalf("expected error %v, got %v", tt.expectErr, err)
+			}
+			if path != tt.expected {
+				t.Errorf("expected %s, got %s", tt.expected, path)
+			}
+		})
+	}
+}
+
+func TestResolveSessionPath_SelectedWorktreeEmptyPath(t *testing.T) {
+	svc := &Service{}
+	session := &taskmodels.TaskSession{
+		ID: "session-1",
+		Worktrees: []*taskmodels.TaskSessionWorktree{
+			{ID: "assoc-1", WorktreeID: "wt-1", WorktreePath: "/path/to/repo-a"},
+			{ID: "assoc-2", WorktreeID: "wt-2", WorktreePath: ""},
+		},
+	}
+	_, err := svc.resolveSessionPath(context.Background(), session, "wt-2")
 	if err != ErrWorkspaceNotFound {
 		t.Errorf("expected ErrWorkspaceNotFound, got %v", err)
 	}
diff --git a/apps/backend/internal/task/dto/converters_test.go b/apps/backend/internal/task/dto/converters_test.go
index 5345ade4ab..54044d414c 100644
--- a/apps/backend/internal/task/dto/converters_test.go
+++ b/apps/backend/internal/task/dto/converters_test.go
@@ -3,6 +3,7 @@ package dto
 import (
 	"testing"
 
+	"github.com/kandev/kandev/internal/task/models"
 	wfmodels "github.com/kandev/kandev/internal/workflow/models"
 )
 
@@ -56,3 +57,30 @@ func TestFromWorkflowStep_PreservesWIPFields(t *testing.T) {
 		t.Fatalf("PullFromStepID = %q, want queue-step", got.PullFromStepID)
 	}
 }
+
+func TestFromTaskSession_IncludesAllWorktrees(t *testing.T) {
+	session := &models.TaskSession{
+		ID:     "session-1",
+		TaskID: "task-1",
+		Worktrees: []*models.TaskSessionWorktree{
+			{ID: "assoc-1", WorktreeID: "wt-1", RepositoryID: "repo-a", WorktreePath: "/x/a"},
+			{ID: "assoc-2", WorktreeID: "wt-2", RepositoryID: "repo-b", WorktreePath: "/x/b"},
+		},
+	}
+
+	full := FromTaskSession(session)
+	if len(full.Worktrees) != 2 {
+		t.Fatalf("FromTaskSession Worktrees len = %d, want 2", len(full.Worktrees))
+	}
+	if full.WorktreePath != "/x/a" {
+		t.Fatalf("WorktreePath = %q, want /x/a (first worktree)", full.WorktreePath)
+	}
+
+	summary := FromTaskSessionSummary(session)
+	if len(summary.Worktrees) != 2 {
+		t.Fatalf("FromTaskSessionSummary Worktrees len = %d, want 2", len(summary.Worktrees))
+	}
+	if summary.Worktrees[1].WorktreeID != "wt-2" {
+		t.Fatalf("second worktree id = %q, want wt-2", summary.Worktrees[1].WorktreeID)
+	}
+}
diff --git a/apps/backend/internal/task/dto/dto.go b/apps/backend/internal/task/dto/dto.go
index 47e3cc8315..805394ebe0 100644
--- a/apps/backend/internal/task/dto/dto.go
+++ b/apps/backend/internal/task/dto/dto.go
@@ -196,29 +196,33 @@ type TaskSessionDTO struct {
 	TaskID string `json:"task_id"`
 	// Name is the user-supplied session tab label. Serialized without
 	// omitempty so a cleared name ("") overwrites stale client state.
-	Name                 string                  `json:"name"`
-	AgentExecutionID     string                  `json:"agent_execution_id,omitempty"`
-	ContainerID          string                  `json:"container_id,omitempty"`
-	AgentProfileID       string                  `json:"agent_profile_id,omitempty"`
-	ExecutorID           string                  `json:"executor_id,omitempty"`
-	ExecutorProfileID    string                  `json:"executor_profile_id,omitempty"`
-	EnvironmentID        string                  `json:"environment_id,omitempty"`
-	RepositoryID         string                  `json:"repository_id,omitempty"`
-	BaseBranch           string                  `json:"base_branch,omitempty"`
-	BaseCommitSHA        string                  `json:"base_commit_sha,omitempty"`
-	WorktreeID           string                  `json:"worktree_id,omitempty"`
-	WorktreePath         string                  `json:"worktree_path,omitempty"`
-	WorktreeBranch       string                  `json:"worktree_branch,omitempty"`
-	State                models.TaskSessionState `json:"state"`
-	ErrorMessage         string                  `json:"error_message,omitempty"`
-	Metadata             map[string]interface{}  `json:"metadata,omitempty"`
-	AgentProfileSnapshot map[string]interface{}  `json:"agent_profile_snapshot,omitempty"`
-	ExecutorSnapshot     map[string]interface{}  `json:"executor_snapshot,omitempty"`
-	EnvironmentSnapshot  map[string]interface{}  `json:"environment_snapshot,omitempty"`
-	RepositorySnapshot   map[string]interface{}  `json:"repository_snapshot,omitempty"`
-	StartedAt            time.Time               `json:"started_at"`
-	CompletedAt          *time.Time              `json:"completed_at,omitempty"`
-	UpdatedAt            time.Time               `json:"updated_at"`
+	Name              string `json:"name"`
+	AgentExecutionID  string `json:"agent_execution_id,omitempty"`
+	ContainerID       string `json:"container_id,omitempty"`
+	AgentProfileID    string `json:"agent_profile_id,omitempty"`
+	ExecutorID        string `json:"executor_id,omitempty"`
+	ExecutorProfileID string `json:"executor_profile_id,omitempty"`
+	EnvironmentID     string `json:"environment_id,omitempty"`
+	RepositoryID      string `json:"repository_id,omitempty"`
+	BaseBranch        string `json:"base_branch,omitempty"`
+	BaseCommitSHA     string `json:"base_commit_sha,omitempty"`
+	WorktreeID        string `json:"worktree_id,omitempty"`
+	WorktreePath      string `json:"worktree_path,omitempty"`
+	WorktreeBranch    string `json:"worktree_branch,omitempty"`
+	// Worktrees lists all session worktrees (one per repo on multi-repo tasks);
+	// the flattened Worktree* fields above carry only the first for
+	// backward compatibility.
+	Worktrees            []*models.TaskSessionWorktree `json:"worktrees,omitempty"`
+	State                models.TaskSessionState       `json:"state"`
+	ErrorMessage         string                        `json:"error_message,omitempty"`
+	Metadata             map[string]interface{}        `json:"metadata,omitempty"`
+	AgentProfileSnapshot map[string]interface{}        `json:"agent_profile_snapshot,omitempty"`
+	ExecutorSnapshot     map[string]interface{}        `json:"executor_snapshot,omitempty"`
+	EnvironmentSnapshot  map[string]interface{}        `json:"environment_snapshot,omitempty"`
+	RepositorySnapshot   map[string]interface{}        `json:"repository_snapshot,omitempty"`
+	StartedAt            time.Time                     `json:"started_at"`
+	CompletedAt          *time.Time                    `json:"completed_at,omitempty"`
+	UpdatedAt            time.Time                     `json:"updated_at"`
 	// Workflow fields
 	IsPrimary         bool                `json:"is_primary"`
 	IsPassthrough     bool                `json:"is_passthrough"`
@@ -233,29 +237,33 @@ type TaskSessionSummaryDTO struct {
 	TaskID string `json:"task_id"`
 	// Name is the user-supplied session tab label. Serialized without
 	// omitempty so a cleared name ("") overwrites stale client state.
-	Name              string                  `json:"name"`
-	AgentExecutionID  string                  `json:"agent_execution_id,omitempty"`
-	ContainerID       string                  `json:"container_id,omitempty"`
-	AgentProfileID    string                  `json:"agent_profile_id,omitempty"`
-	ExecutorID        string                  `json:"executor_id,omitempty"`
-	ExecutorProfileID string                  `json:"executor_profile_id,omitempty"`
-	EnvironmentID     string                  `json:"environment_id,omitempty"`
-	RepositoryID      string                  `json:"repository_id,omitempty"`
-	BaseBranch        string                  `json:"base_branch,omitempty"`
-	BaseCommitSHA     string                  `json:"base_commit_sha,omitempty"`
-	WorktreeID        string                  `json:"worktree_id,omitempty"`
-	WorktreePath      string                  `json:"worktree_path,omitempty"`
-	WorktreeBranch    string                  `json:"worktree_branch,omitempty"`
-	State             models.TaskSessionState `json:"state"`
-	ErrorMessage      string                  `json:"error_message,omitempty"`
-	Metadata          map[string]interface{}  `json:"metadata,omitempty"`
-	StartedAt         time.Time               `json:"started_at"`
-	CompletedAt       *time.Time              `json:"completed_at,omitempty"`
-	UpdatedAt         time.Time               `json:"updated_at"`
-	IsPrimary         bool                    `json:"is_primary"`
-	IsPassthrough     bool                    `json:"is_passthrough"`
-	ReviewStatus      models.ReviewStatus     `json:"review_status,omitempty"`
-	TaskEnvironmentID string                  `json:"task_environment_id,omitempty"`
+	Name              string `json:"name"`
+	AgentExecutionID  string `json:"agent_execution_id,omitempty"`
+	ContainerID       string `json:"container_id,omitempty"`
+	AgentProfileID    string `json:"agent_profile_id,omitempty"`
+	ExecutorID        string `json:"executor_id,omitempty"`
+	ExecutorProfileID string `json:"executor_profile_id,omitempty"`
+	EnvironmentID     string `json:"environment_id,omitempty"`
+	RepositoryID      string `json:"repository_id,omitempty"`
+	BaseBranch        string `json:"base_branch,omitempty"`
+	BaseCommitSHA     string `json:"base_commit_sha,omitempty"`
+	WorktreeID        string `json:"worktree_id,omitempty"`
+	WorktreePath      string `json:"worktree_path,omitempty"`
+	WorktreeBranch    string `json:"worktree_branch,omitempty"`
+	// Worktrees lists all session worktrees (one per repo on multi-repo tasks);
+	// the flattened Worktree* fields above carry only the first for
+	// backward compatibility.
+	Worktrees         []*models.TaskSessionWorktree `json:"worktrees,omitempty"`
+	State             models.TaskSessionState       `json:"state"`
+	ErrorMessage      string                        `json:"error_message,omitempty"`
+	Metadata          map[string]interface{}        `json:"metadata,omitempty"`
+	StartedAt         time.Time                     `json:"started_at"`
+	CompletedAt       *time.Time                    `json:"completed_at,omitempty"`
+	UpdatedAt         time.Time                     `json:"updated_at"`
+	IsPrimary         bool                          `json:"is_primary"`
+	IsPassthrough     bool                          `json:"is_passthrough"`
+	ReviewStatus      models.ReviewStatus           `json:"review_status,omitempty"`
+	TaskEnvironmentID string                        `json:"task_environment_id,omitempty"`
 	// CommandCount is the number of tool_call messages on this session,
 	// surfaced inline in the timeline entry header ("ran N commands").
 	// Populated by ListTaskSessions; defaults to 0 for callers that don't
@@ -662,6 +670,7 @@ func FromTaskSessionSummary(session *models.TaskSession) TaskSessionSummaryDTO {
 		result.WorktreeID = session.Worktrees[0].WorktreeID
 		result.WorktreePath = session.Worktrees[0].WorktreePath
 		result.WorktreeBranch = session.Worktrees[0].WorktreeBranch
+		result.Worktrees = session.Worktrees
 	}
 	return result
 }
@@ -700,6 +709,7 @@ func FromTaskSession(session *models.TaskSession) TaskSessionDTO {
 		result.WorktreeID = session.Worktrees[0].WorktreeID
 		result.WorktreePath = session.Worktrees[0].WorktreePath
 		result.WorktreeBranch = session.Worktrees[0].WorktreeBranch
+		result.Worktrees = session.Worktrees
 	}
 	return result
 }
diff --git a/apps/web/components/task/editor-worktree-options.test.ts b/apps/web/components/task/editor-worktree-options.test.ts
new file mode 100644
index 0000000000..6cca74076a
--- /dev/null
+++ b/apps/web/components/task/editor-worktree-options.test.ts
@@ -0,0 +1,44 @@
+import { describe, expect, it } from "vitest";
+import { buildWorktreeOptions } from "./editor-worktree-options";
+import type { Worktree } from "@/lib/state/slices/session/types";
+import type { Repository } from "@/lib/types/http";
+
+function repo(id: string, name: string): Repository {
+  return { id, name } as Repository;
+}
+
+describe("buildWorktreeOptions", () => {
+  it("labels worktrees with their repository name", () => {
+    const worktrees: Worktree[] = [
+      { id: "wt-1", sessionId: "s-1", repositoryId: "repo-a", path: "/tasks/x/a", branch: "kd/x" },
+      { id: "wt-2", sessionId: "s-1", repositoryId: "repo-b", path: "/tasks/x/b", branch: "kd/y" },
+    ];
+    const options = buildWorktreeOptions(worktrees, [repo("repo-a", "api"), repo("repo-b", "web")]);
+    expect(options).toEqual([
+      { worktreeId: "wt-1", label: "api", branch: "kd/x" },
+      { worktreeId: "wt-2", label: "web", branch: "kd/y" },
+    ]);
+  });
+
+  it("falls back to the worktree folder name when the repository is unknown", () => {
+    const worktrees: Worktree[] = [
+      { id: "wt-1", sessionId: "s-1", repositoryId: "missing", path: "/tasks/x/kandev" },
+    ];
+    const options = buildWorktreeOptions(worktrees, []);
+    expect(options).toEqual([{ worktreeId: "wt-1", label: "kandev", branch: undefined }]);
+  });
+
+  it("handles Windows-style paths", () => {
+    const worktrees: Worktree[] = [{ id: "wt-1", sessionId: "s-1", path: "C:\\tasks\\x\\kandev" }];
+    expect(buildWorktreeOptions(worktrees, [])[0].label).toBe("kandev");
+  });
+
+  it("falls back to a positional label without repository or path", () => {
+    const worktrees: Worktree[] = [
+      { id: "wt-1", sessionId: "s-1" },
+      { id: "wt-2", sessionId: "s-1" },
+    ];
+    const options = buildWorktreeOptions(worktrees, []);
+    expect(options.map((o) => o.label)).toEqual(["Worktree 1", "Worktree 2"]);
+  });
+});
diff --git a/apps/web/components/task/editor-worktree-options.ts b/apps/web/components/task/editor-worktree-options.ts
new file mode 100644
index 0000000000..04ca065632
--- /dev/null
+++ b/apps/web/components/task/editor-worktree-options.ts
@@ -0,0 +1,29 @@
+import type { Worktree } from "@/lib/state/slices/session/types";
+import type { Repository } from "@/lib/types/http";
+
+export type WorktreeOption = {
+  worktreeId: string;
+  label: string;
+  branch?: string;
+};
+
+function worktreePathBasename(path: string | undefined): string | undefined {
+  if (!path) return undefined;
+  return path.split(/[\\/]/).filter(Boolean).pop();
+}
+
+/**
+ * Builds display options for a session's worktrees: labeled by repository name
+ * when known, otherwise by the worktree folder name.
+ */
+export function buildWorktreeOptions(
+  worktrees: Worktree[],
+  repositories: Repository[],
+): WorktreeOption[] {
+  return worktrees.map((worktree, index) => {
+    const repository = repositories.find((repo) => repo.id === worktree.repositoryId);
+    const label =
+      repository?.name ?? worktreePathBasename(worktree.path) ?? `Worktree ${index + 1}`;
+    return { worktreeId: worktree.id, label, branch: worktree.branch };
+  });
+}
diff --git a/apps/web/components/task/editors-menu.tsx b/apps/web/components/task/editors-menu.tsx
index 5989337378..80b3683d0e 100644
--- a/apps/web/components/task/editors-menu.tsx
+++ b/apps/web/components/task/editors-menu.tsx
@@ -7,22 +7,171 @@ import {
   DropdownMenu,
   DropdownMenuContent,
   DropdownMenuItem,
+  DropdownMenuSub,
+  DropdownMenuSubContent,
+  DropdownMenuSubTrigger,
   DropdownMenuTrigger,
 } from "@kandev/ui/dropdown-menu";
 import { Tooltip, TooltipContent, TooltipTrigger } from "@kandev/ui/tooltip";
 import { useEditors } from "@/hooks/domains/settings/use-editors";
 import { useOpenSessionInEditor } from "@/hooks/use-open-session-in-editor";
+import { useSessionWorktrees } from "@/hooks/domains/session/use-session-worktrees";
 import { useAppStore } from "@/components/state-provider";
 import type { EditorOption } from "@/lib/types/http";
+import {
+  buildWorktreeOptions,
+  type WorktreeOption,
+} from "@/components/task/editor-worktree-options";
+
+const menuItemClass = "cursor-pointer";
 
 type EditorsMenuProps = {
   activeSessionId: string | null;
 };
 
+function useWorktreeOptions(sessionId: string | null): WorktreeOption[] {
+  const worktrees = useSessionWorktrees(sessionId);
+  const repositoriesByWorkspace = useAppStore((state) => state.repositories.itemsByWorkspaceId);
+  return useMemo(
+    () => buildWorktreeOptions(worktrees, Object.values(repositoriesByWorkspace).flat()),
+    [worktrees, repositoriesByWorkspace],
+  );
+}
+
+function WorktreeItems({
+  options,
+  onSelect,
+}: {
+  options: WorktreeOption[];
+  onSelect: (worktreeId: string) => void;
+}) {
+  return (
+    <>
+      {options.map((option) => (
+        <DropdownMenuItem
+          key={option.worktreeId}
+          className={menuItemClass}
+          data-testid="editors-menu-worktree-item"
+          onClick={() => onSelect(option.worktreeId)}
+        >
+          <span className="truncate">{option.label}</span>
+          {option.branch && (
+            <span className="ml-auto pl-3 text-xs text-muted-foreground truncate max-w-40">
+              {option.branch}
+            </span>
+          )}
+        </DropdownMenuItem>
+      ))}
+    </>
+  );
+}
+
+function OpenEditorButton({
+  disabled,
+  isLoading,
+  tooltip,
+  worktreeOptions,
+  onOpen,
+}: {
+  disabled: boolean;
+  isLoading: boolean;
+  tooltip: string;
+  worktreeOptions: WorktreeOption[];
+  onOpen: (worktreeId?: string) => void;
+}) {
+  const icon = isLoading ? (
+    <IconLoader2 className="h-4 w-4 animate-spin" />
+  ) : (
+    <IconCode className="h-4 w-4" />
+  );
+  const buttonClass = "rounded-none border-0 cursor-pointer px-2 focus-visible:ring-inset";
+
+  // Multi-worktree sessions get a picker instead of opening the first worktree.
+  // The focusable span keeps the tooltip reachable while the button is
+  // disabled (disabled buttons receive no pointer/focus events).
+  if (worktreeOptions.length > 1) {
+    return (
+      <DropdownMenu>
+        <Tooltip>
+          <TooltipTrigger asChild>
+            <span tabIndex={disabled ? 0 : -1} className="inline-flex">
+              <DropdownMenuTrigger asChild>
+                <Button
+                  size="sm"
+                  variant="outline"
+                  className={buttonClass}
+                  data-testid="editors-menu-open"
+                  disabled={disabled}
+                >
+                  {icon}
+                </Button>
+              </DropdownMenuTrigger>
+            </span>
+          </TooltipTrigger>
+          <TooltipContent>{tooltip}</TooltipContent>
+        </Tooltip>
+        <DropdownMenuContent align="end" className="min-w-56 w-auto">
+          <WorktreeItems options={worktreeOptions} onSelect={(worktreeId) => onOpen(worktreeId)} />
+        </DropdownMenuContent>
+      </DropdownMenu>
+    );
+  }
+
+  return (
+    <Tooltip>
+      <TooltipTrigger asChild>
+        <span tabIndex={disabled ? 0 : -1} className="inline-flex">
+          <Button
+            size="sm"
+            variant="outline"
+            className={buttonClass}
+            data-testid="editors-menu-open"
+            onClick={() => onOpen()}
+            disabled={disabled}
+          >
+            {icon}
+          </Button>
+        </span>
+      </TooltipTrigger>
+      <TooltipContent>{tooltip}</TooltipContent>
+    </Tooltip>
+  );
+}
+
+function EditorMenuEntry({
+  editor,
+  worktreeOptions,
+  onOpen,
+}: {
+  editor: EditorOption;
+  worktreeOptions: WorktreeOption[];
+  onOpen: (editorId: string, worktreeId?: string) => void;
+}) {
+  if (worktreeOptions.length > 1) {
+    return (
+      <DropdownMenuSub>
+        <DropdownMenuSubTrigger className={menuItemClass}>{editor.name}</DropdownMenuSubTrigger>
+        <DropdownMenuSubContent className="min-w-56 w-auto">
+          <WorktreeItems
+            options={worktreeOptions}
+            onSelect={(worktreeId) => onOpen(editor.id, worktreeId)}
+          />
+        </DropdownMenuSubContent>
+      </DropdownMenuSub>
+    );
+  }
+  return (
+    <DropdownMenuItem className={menuItemClass} onClick={() => onOpen(editor.id)}>
+      {editor.name}
+    </DropdownMenuItem>
+  );
+}
+
 export function EditorsMenu({ activeSessionId }: EditorsMenuProps) {
   const openEditor = useOpenSessionInEditor(activeSessionId ?? null);
   const { editors } = useEditors();
   const defaultEditorId = useAppStore((state) => state.userSettings.defaultEditorId);
+  const worktreeOptions = useWorktreeOptions(activeSessionId ?? null);
 
   const enabledEditors = useMemo(
     () =>
@@ -44,37 +193,27 @@ export function EditorsMenu({ activeSessionId }: EditorsMenuProps) {
     return enabledEditors[0]?.id ?? "";
   }, [defaultEditorId, enabledEditors]);
 
+  const openWith = (editorId: string, worktreeId?: string) => {
+    if (!editorId) return;
+    void openEditor.open({ editorId, worktreeId });
+  };
+
   return (
     <div className="inline-flex h-7 rounded-md border border-border overflow-hidden">
-      <Tooltip>
-        <TooltipTrigger asChild>
-          <Button
-            size="sm"
-            variant="outline"
-            className="rounded-none border-0 cursor-pointer px-2 focus-visible:ring-inset"
-            onClick={() => {
-              if (!resolvedEditorId) return;
-              void openEditor.open({ editorId: resolvedEditorId });
-            }}
-            disabled={!activeSessionId || openEditor.isLoading || enabledEditors.length === 0}
-          >
-            {openEditor.isLoading ? (
-              <IconLoader2 className="h-4 w-4 animate-spin" />
-            ) : (
-              <IconCode className="h-4 w-4" />
-            )}
-          </Button>
-        </TooltipTrigger>
-        <TooltipContent>
-          {activeSessionId ? "Open editor" : "Select a session to open its worktree"}
-        </TooltipContent>
-      </Tooltip>
+      <OpenEditorButton
+        disabled={!activeSessionId || openEditor.isLoading || enabledEditors.length === 0}
+        isLoading={openEditor.isLoading}
+        tooltip={activeSessionId ? "Open editor" : "Select a session to open its worktree"}
+        worktreeOptions={worktreeOptions}
+        onOpen={(worktreeId) => openWith(resolvedEditorId, worktreeId)}
+      />
       <DropdownMenu>
         <DropdownMenuTrigger asChild>
           <Button
             size="sm"
             variant="outline"
             className="rounded-none border-0 border-l px-2 cursor-pointer focus-visible:ring-inset"
+            data-testid="editors-menu-list"
             disabled={!activeSessionId || enabledEditors.length === 0}
           >
             <IconChevronDown className="h-4 w-4" />
@@ -85,15 +224,12 @@ export function EditorsMenu({ activeSessionId }: EditorsMenuProps) {
             <DropdownMenuItem disabled>No editors available</DropdownMenuItem>
           ) : (
             enabledEditors.map((editor: EditorOption) => (
-              <DropdownMenuItem
+              <EditorMenuEntry
                 key={editor.id}
-                className="cursor-pointer"
-                onClick={() => {
-                  void openEditor.open({ editorId: editor.id });
-                }}
-              >
-                {editor.name}
-              </DropdownMenuItem>
+                editor={editor}
+                worktreeOptions={worktreeOptions}
+                onOpen={openWith}
+              />
             ))
           )}
         </DropdownMenuContent>
diff --git a/apps/web/e2e/tests/task/editors-menu-worktree-picker.spec.ts b/apps/web/e2e/tests/task/editors-menu-worktree-picker.spec.ts
new file mode 100644
index 0000000000..5d135714f1
--- /dev/null
+++ b/apps/web/e2e/tests/task/editors-menu-worktree-picker.spec.ts
@@ -0,0 +1,74 @@
+import { execSync } from "node:child_process";
+import fs from "node:fs";
+import path from "node:path";
+
+import { test, expect } from "../../fixtures/test-base";
+import { SessionPage } from "../../pages/session-page";
+import { makeGitEnv } from "../../helpers/git-helper";
+
+const DONE_STATES = ["COMPLETED", "WAITING_FOR_INPUT", "IDLE"];
+
+/**
+ * Multi-repo tasks create one worktree per repository. The IDE button in the
+ * task top bar must offer a worktree picker instead of silently opening the
+ * first worktree (regression: it always opened Worktrees[0]).
+ */
+test.describe("Editors menu worktree picker", () => {
+  test("multi-repo task offers a worktree choice on the IDE button", async ({
+    testPage,
+    apiClient,
+    seedData,
+    backend,
+  }) => {
+    // Two disposable repos so the session materializes two worktrees.
+    const gitEnv = makeGitEnv(backend.tmpDir);
+    const repoIds: string[] = [];
+    for (const name of ["orders-api", "storefront-web"]) {
+      const repoDir = path.join(backend.tmpDir, "repos", name);
+      fs.mkdirSync(repoDir, { recursive: true });
+      execSync("git init -b main", { cwd: repoDir, env: gitEnv });
+      execSync('git commit --allow-empty -m "init"', { cwd: repoDir, env: gitEnv });
+      const repo = await apiClient.createRepository(seedData.workspaceId, repoDir, "main", {
+        name,
+      });
+      repoIds.push(repo.id);
+    }
+
+    const task = await apiClient.createTaskWithAgent(
+      seedData.workspaceId,
+      "Sync order totals across services",
+      seedData.agentProfileId,
+      {
+        description: "/e2e:simple-message",
+        workflow_id: seedData.workflowId,
+        workflow_step_id: seedData.startStepId,
+        repository_ids: repoIds,
+        executor_profile_id: seedData.worktreeExecutorProfileId,
+      },
+    );
+
+    await expect
+      .poll(
+        async () => {
+          const { sessions } = await apiClient.listTaskSessions(task.id);
+          return DONE_STATES.includes(sessions[0]?.state ?? "");
+        },
+        { timeout: 60_000, message: "Waiting for the agent session to finish" },
+      )
+      .toBe(true);
+
+    await testPage.goto(`/t/${task.id}`);
+    const session = new SessionPage(testPage);
+    await session.waitForLoad();
+    // Park focus on the idle chat composer before opening the menu so a late
+    // composer autofocus can't steal focus and dismiss the Radix dropdown.
+    await session.idleInput().click();
+
+    // The IDE button now opens a worktree picker instead of launching directly.
+    await testPage.getByTestId("editors-menu-open").click();
+    const items = testPage.getByTestId("editors-menu-worktree-item");
+    await expect(items).toHaveCount(2);
+    await expect(items.filter({ hasText: "orders-api" })).toBeVisible();
+    await expect(items.filter({ hasText: "storefront-web" })).toBeVisible();
+  });
+});
diff --git a/apps/web/hooks/domains/session/use-session-worktrees.test.ts b/apps/web/hooks/domains/session/use-session-worktrees.test.ts
new file mode 100644
index 0000000000..69e2e3a09a
--- /dev/null
+++ b/apps/web/hooks/domains/session/use-session-worktrees.test.ts
@@ -0,0 +1,121 @@
+import { describe, expect, it } from "vitest";
+import { resolveSessionWorktrees } from "./use-session-worktrees";
+import type { Worktree } from "@/lib/state/slices/session/types";
+import type { RepositoryId, SessionId, TaskSession, TaskSessionWorktree } from "@/lib/types/http";
+
+const SESSION_ID = "session-1" as SessionId;
+
+function session(overrides: Partial<TaskSession>): TaskSession {
+  return { id: SESSION_ID, task_id: "task-1", state: "RUNNING", ...overrides } as TaskSession;
+}
+
+function apiWorktree(overrides: Partial<TaskSessionWorktree>): TaskSessionWorktree {
+  return {
+    id: "assoc-1",
+    session_id: SESSION_ID,
+    worktree_id: "wt-1",
+    position: 0,
+    ...overrides,
+  };
+}
+
+describe("resolveSessionWorktrees", () => {
+  it("prefers the API worktree list, ordered by position", () => {
+    const result = resolveSessionWorktrees(
+      SESSION_ID,
+      session({
+        worktrees: [
+          apiWorktree({
+            id: "assoc-2",
+            worktree_id: "wt-2",
+            position: 1,
+            repository_id: "repo-b" as RepositoryId,
+            worktree_path: "/x/b",
+            worktree_branch: "kd/b",
+          }),
+          apiWorktree({
+            id: "assoc-1",
+            worktree_id: "wt-1",
+            position: 0,
+            repository_id: "repo-a" as RepositoryId,
+            worktree_path: "/x/a",
+            worktree_branch: "kd/a",
+          }),
+        ],
+      }),
+      {},
+      undefined,
+    );
+    expect(result).toEqual([
+      { id: "wt-1", sessionId: SESSION_ID, repositoryId: "repo-a", path: "/x/a", branch: "kd/a" },
+      { id: "wt-2", sessionId: SESSION_ID, repositoryId: "repo-b", path: "/x/b", branch: "kd/b" },
+    ]);
+  });
+
+  it("fills in missing API fields from the live worktrees map", () => {
+    const live: Record<string, Worktree> = {
+      "wt-1": { id: "wt-1", sessionId: SESSION_ID, repositoryId: "repo-a", path: "/x/a" },
+    };
+    const result = resolveSessionWorktrees(
+      SESSION_ID,
+      session({ worktrees: [apiWorktree({ worktree_id: "wt-1" })] }),
+      live,
+      undefined,
+    );
+    expect(result[0]).toMatchObject({ id: "wt-1", repositoryId: "repo-a", path: "/x/a" });
+  });
+
+  it("treats empty-string API fields as missing and falls back to live values", () => {
+    const live: Record<string, Worktree> = {
+      "wt-1": { id: "wt-1", sessionId: SESSION_ID, path: "/x/a", branch: "kd/a" },
+    };
+    const result = resolveSessionWorktrees(
+      SESSION_ID,
+      session({
+        worktrees: [apiWorktree({ worktree_id: "wt-1", worktree_path: "", worktree_branch: "" })],
+      }),
+      live,
+      undefined,
+    );
+    expect(result[0]).toMatchObject({ id: "wt-1", path: "/x/a", branch: "kd/a" });
+  });
+
+  it("unions WS-only worktrees with the API list", () => {
+    const live: Record<string, Worktree> = {
+      "wt-1": { id: "wt-1", sessionId: SESSION_ID, path: "/x/a" },
+      "wt-2": { id: "wt-2", sessionId: SESSION_ID, path: "/x/b" },
+    };
+    const result = resolveSessionWorktrees(
+      SESSION_ID,
+      session({ worktrees: [apiWorktree({ worktree_id: "wt-1", worktree_path: "/x/a" })] }),
+      live,
+      ["wt-1", "wt-2"],
+    );
+    expect(result.map((wt) => wt.id)).toEqual(["wt-1", "wt-2"]);
+  });
+
+  it("falls back to the WS per-session list when the API list is empty", () => {
+    const live: Record<string, Worktree> = {
+      "wt-1": { id: "wt-1", sessionId: SESSION_ID, path: "/x/a" },
+    };
+    const result = resolveSessionWorktrees(SESSION_ID, session({}), live, ["wt-1", "wt-gone"]);
+    expect(result).toEqual([live["wt-1"]]);
+  });
+
+  it("falls back to the legacy single worktree_id field", () => {
+    const live: Record<string, Worktree> = {
+      "wt-1": { id: "wt-1", sessionId: SESSION_ID, path: "/x/a" },
+    };
+    const result = resolveSessionWorktrees(
+      SESSION_ID,
+      session({ worktree_id: "wt-1" }),
+      live,
+      undefined,
+    );
+    expect(result).toEqual([live["wt-1"]]);
+  });
+
+  it("returns empty when nothing is known", () => {
+    expect(resolveSessionWorktrees(SESSION_ID, session({}), {}, undefined)).toEqual([]);
+  });
+});
diff --git a/apps/web/hooks/domains/session/use-session-worktrees.ts b/apps/web/hooks/domains/session/use-session-worktrees.ts
index be8389df24..a44268808e 100644
--- a/apps/web/hooks/domains/session/use-session-worktrees.ts
+++ b/apps/web/hooks/domains/session/use-session-worktrees.ts
@@ -1,6 +1,50 @@
 import { useMemo } from "react";
 import { useAppStore } from "@/components/state-provider";
 import { useSession } from "@/hooks/domains/session/use-session";
+import type { Worktree } from "@/lib/state/slices/session/types";
+import type { TaskSession } from "@/lib/types/http";
+
+/**
+ * Resolves the worktrees of a session by unioning the API-provided
+ * `session.worktrees` (complete, survives reloads) with the WS-populated
+ * per-session list (fresher after live add-branch events), filling in details
+ * from the WS worktrees map. Falls back to the legacy single `worktree_id`
+ * field when neither source has entries.
+ */
+export function resolveSessionWorktrees(
+  sessionId: string,
+  session: TaskSession | null,
+  worktrees: Record<string, Worktree>,
+  sessionWorktreeIds: string[] | undefined,
+): Worktree[] {
+  const result: Worktree[] = [...(session?.worktrees ?? [])]
+    .sort((a, b) => a.position - b.position)
+    .map((wt) => {
+      const id = wt.worktree_id || wt.id;
+      const live = worktrees[id];
+      // `||` (not `??`): the Go backend may serialize these as empty strings,
+      // which should also fall back to the live WS-populated values.
+      return {
+        id,
+        sessionId,
+        repositoryId: wt.repository_id || live?.repositoryId,
+        path: wt.worktree_path || live?.path,
+        branch: wt.worktree_branch || live?.branch,
+      };
+    });
+  const seen = new Set(result.map((wt) => wt.id));
+  for (const id of sessionWorktreeIds ?? []) {
+    const live = worktrees[id];
+    if (!live || seen.has(id)) continue;
+    seen.add(id);
+    result.push(live);
+  }
+  if (result.length === 0 && session?.worktree_id) {
+    const worktree = worktrees[session.worktree_id];
+    return worktree ? [worktree] : [];
+  }
+  return result;
+}
 
 export function useSessionWorktrees(sessionId: string | null) {
   const { session } = useSession(sessionId);
@@ -11,14 +55,11 @@ export function useSessionWorktrees(sessionId: string | null) {
 
   return useMemo(() => {
     if (!sessionId) return [];
-    const worktreeIds = sessionWorktreesBySessionId[sessionId];
-    if (worktreeIds?.length) {
-      return worktreeIds.map((id: string) => worktrees[id]).filter(Boolean);
-    }
-    if (session?.worktree_id) {
-      const worktree = worktrees[session.worktree_id];
-      return worktree ? [worktree] : [];
-    }
-    return [];
-  }, [session?.worktree_id, sessionId, sessionWorktreesBySessionId, worktrees]);
+    return resolveSessionWorktrees(
+      sessionId,
+      session,
+      worktrees,
+      sessionWorktreesBySessionId[sessionId],
+    );
+  }, [session, sessionId, sessionWorktreesBySessionId, worktrees]);
 }
diff --git a/apps/web/hooks/use-open-session-in-editor.test.ts b/apps/web/hooks/use-open-session-in-editor.test.ts
new file mode 100644
index 0000000000..7810553278
--- /dev/null
+++ b/apps/web/hooks/use-open-session-in-editor.test.ts
@@ -0,0 +1,66 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { renderHook } from "@testing-library/react";
+
+const mockOpenSessionInEditor = vi.fn();
+const mockOpenFileInVscode = vi.fn();
+const mockOpenInternalVscode = vi.fn();
+
+vi.mock("@/lib/api", () => ({
+  openSessionInEditor: (...args: unknown[]) => mockOpenSessionInEditor(...args),
+}));
+
+vi.mock("@/lib/api/domains/vscode-api", () => ({
+  openFileInVscode: (...args: unknown[]) => mockOpenFileInVscode(...args),
+}));
+
+vi.mock("@/lib/state/dockview-store", () => ({
+  useDockviewStore: {
+    getState: () => ({ openInternalVscode: mockOpenInternalVscode }),
+  },
+}));
+
+vi.mock("@/lib/http/use-request", () => ({
+  useRequest: (fn: (options?: unknown) => Promise<unknown>) => ({
+    run: fn,
+    status: "idle",
+    isLoading: false,
+  }),
+}));
+
+import { useOpenSessionInEditor } from "./use-open-session-in-editor";
+
+describe("useOpenSessionInEditor", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    mockOpenSessionInEditor.mockResolvedValue({});
+  });
+
+  it("forwards the selected worktree as worktree_id", async () => {
+    const { result } = renderHook(() => useOpenSessionInEditor("session-1"));
+
+    await result.current.open({ editorId: "editor-1", worktreeId: "wt-2" });
+
+    expect(mockOpenSessionInEditor).toHaveBeenCalledWith(
+      "session-1",
+      expect.objectContaining({ editor_id: "editor-1", worktree_id: "wt-2" }),
+      expect.anything(),
+    );
+  });
+
+  it("omits worktree_id when no worktree is selected", async () => {
+    const { result } = renderHook(() => useOpenSessionInEditor("session-1"));
+
+    await result.current.open({ editorId: "editor-1" });
+
+    const payload = mockOpenSessionInEditor.mock.calls[0][1] as Record<string, unknown>;
+    expect(payload.worktree_id).toBeUndefined();
+  });
+
+  it("does not call the API without a session id", async () => {
+    const { result } = renderHook(() => useOpenSessionInEditor(null));
+
+    await result.current.open({ editorId: "editor-1", worktreeId: "wt-2" });
+
+    expect(mockOpenSessionInEditor).not.toHaveBeenCalled();
+  });
+});
diff --git a/apps/web/hooks/use-open-session-in-editor.ts b/apps/web/hooks/use-open-session-in-editor.ts
index 4f9f87f332..2db61e2b87 100644
--- a/apps/web/hooks/use-open-session-in-editor.ts
+++ b/apps/web/hooks/use-open-session-in-editor.ts
@@ -11,6 +11,7 @@ type OpenEditorOptions = {
   column?: number;
   editorId?: string;
   editorType?: string;
+  worktreeId?: string;
 };
 
 /**
@@ -46,6 +47,7 @@ export function useOpenSessionInEditor(sessionId?: string | null) {
         file_path: options?.filePath,
         line: options?.line,
         column: options?.column,
+        worktree_id: options?.worktreeId,
       },
       { cache: "no-store" },
     );
diff --git a/apps/web/lib/api/domains/session-api.ts b/apps/web/lib/api/domains/session-api.ts
index 9e13c2c41f..a8cf179c1b 100644
--- a/apps/web/lib/api/domains/session-api.ts
+++ b/apps/web/lib/api/domains/session-api.ts
@@ -122,6 +122,7 @@ export async function openSessionInEditor(
     file_path: string;
     line: number;
     column: number;
+    worktree_id: string;
   }>,
   options?: ApiRequestOptions,
 ) {
diff --git a/apps/web/lib/types/http.ts b/apps/web/lib/types/http.ts
index f044650991..e7e58fa67d 100644
--- a/apps/web/lib/types/http.ts
+++ b/apps/web/lib/types/http.ts
@@ -362,6 +362,20 @@ export type MoveTaskResponse = {
   workflow_step: WorkflowStepDTO;
 };
 
+/** A worktree associated with a task session (one per repo on multi-repo tasks). */
+export type TaskSessionWorktree = {
+  /** Session-worktree association ID. */
+  id: string;
+  session_id: SessionId;
+  worktree_id: string;
+  repository_id?: RepositoryId;
+  branch_slug?: string;
+  position: number;
+  worktree_path?: string;
+  worktree_branch?: string;
+  created_at?: string;
+};
+
 export type TaskSession = {
   id: SessionId;
   task_id: TaskId;
@@ -377,6 +391,7 @@ export type TaskSession = {
   worktree_id?: string;
   worktree_path?: string;
   worktree_branch?: string;
+  worktrees?: TaskSessionWorktree[];
   task_environment_id?: string;
   state: TaskSessionState;
   error_message?: string;