feat(ai): List saved assistant sessions so past chats can be resumed

internal/ai/session.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -181,6 +182,87 @@ func (st *SessionStore) PruneOlderThan(cutoff time.Time) int {
 	return removed
 }
 
+// SessionSummary is the lightweight view of a session for a list, without the
+// full transcript.
+type SessionSummary struct {
+	ID         string       `json:"id"`
+	Scope      string       `json:"scope"`
+	Deployment string       `json:"deployment,omitempty"`
+	Status     string       `json:"status"`
+	Title      string       `json:"title"`
+	CreatedBy  SessionActor `json:"created_by"`
+	CreatedAt  time.Time    `json:"created_at"`
+	UpdatedAt  time.Time    `json:"updated_at"`
+}
+
+// Title derives a short label from the first visible user turn, so a saved
+// session is recognizable in a list. Falls back to the scope.
+func (s *Session) Title() string {
+	for _, m := range s.Messages {
+		if m.Role != "user" || m.Hidden {
+			continue
+		}
+		text := m.Display
+		if text == "" {
+			text = m.Content
+		}
+		if text = strings.TrimSpace(text); text == "" {
+			continue
+		}
+		return truncateTitle(text)
+	}
+	if s.Deployment != "" {
+		return s.Deployment + " chat"
+	}
+	return "System chat"
+}
+
+func truncateTitle(s string) string {
+	s = strings.Join(strings.Fields(s), " ")
+	if r := []rune(s); len(r) > 80 {
+		return string(r[:79]) + "…"
+	}
+	return s
+}
+
+// Summary is the session without its transcript, for a list view.
+func (s *Session) Summary() SessionSummary {
+	return SessionSummary{
+		ID:         s.ID,
+		Scope:      s.Scope,
+		Deployment: s.Deployment,
+		Status:     s.Status,
+		Title:      s.Title(),
+		CreatedBy:  s.CreatedBy,
+		CreatedAt:  s.CreatedAt,
+		UpdatedAt:  s.UpdatedAt,
+	}
+}
+
+// List returns a summary of every stored session, most recently updated first.
+func (st *SessionStore) List() ([]SessionSummary, error) {
+	entries, err := os.ReadDir(st.dir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return []SessionSummary{}, nil
+		}
+		return nil, err
+	}
+	summaries := []SessionSummary{}
+	for _, e := range entries {
+		if e.IsDir() || !strings.HasSuffix(e.Name(), ".json") {
+			continue
+		}
+		sess, err := st.Get(strings.TrimSuffix(e.Name(), ".json"))
+		if err != nil {
+			continue
+		}
+		summaries = append(summaries, sess.Summary())
+	}
+	sort.Slice(summaries, func(i, j int) bool { return summaries[i].UpdatedAt.After(summaries[j].UpdatedAt) })
+	return summaries, nil
+}
+
 // DisplayMessages projects the transcript into UI-facing turns,
 // dropping the system prompt and pairing tool calls with their results.
 type DisplayToolStep struct {

internal/ai/session_list_test.go

@@ -0,0 +1,76 @@
+package ai
+
+import (
+	"testing"
+	"time"
+)
+
+func TestSessionTitle(t *testing.T) {
+	// First visible user turn becomes the title.
+	s := NewSession(SessionScopeSystem, "", true, SessionActor{ID: "u1"}, "sys")
+	s.AddUserMessage("api.example.com:443 request with logs...", "why is wordpress unhealthy?", true) // hidden, skipped
+	s.AddUserMessage("summarize recent security events", "", false)
+	if got := s.Title(); got != "summarize recent security events" {
+		t.Errorf("title should come from the first visible user turn, got %q", got)
+	}
+
+	// No user turn yet: fall back to the deployment name.
+	empty := NewSession(SessionScopeDeployment, "shop", true, SessionActor{ID: "u1"}, "sys")
+	if got := empty.Title(); got != "shop chat" {
+		t.Errorf("deployment fallback title, got %q", got)
+	}
+
+	// System scope with no user turn.
+	sys := NewSession(SessionScopeSystem, "", true, SessionActor{ID: "u1"}, "sys")
+	if got := sys.Title(); got != "System chat" {
+		t.Errorf("system fallback title, got %q", got)
+	}
+}
+
+func TestSessionStoreList(t *testing.T) {
+	st := NewSessionStore(t.TempDir())
+
+	older := NewSession(SessionScopeSystem, "", true, SessionActor{ID: "u1", Name: "alice"}, "sys")
+	older.AddUserMessage("first question", "", false)
+	if err := st.Save(older); err != nil {
+		t.Fatal(err)
+	}
+
+	newer := NewSession(SessionScopeDeployment, "shop", true, SessionActor{ID: "u2", Name: "bob"}, "sys")
+	newer.UpdatedAt = time.Now().UTC().Add(time.Minute)
+	if err := st.Save(newer); err != nil {
+		t.Fatal(err)
+	}
+
+	list, err := st.List()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(list) != 2 {
+		t.Fatalf("expected 2 summaries, got %d", len(list))
+	}
+	if list[0].ID != newer.ID {
+		t.Errorf("expected the most recently updated session first")
+	}
+	if list[0].Title != "shop chat" {
+		t.Errorf("unexpected title %q", list[0].Title)
+	}
+	if list[1].Title != "first question" {
+		t.Errorf("unexpected title %q", list[1].Title)
+	}
+	// The owner must ride along so the handler can filter by actor.
+	if list[1].CreatedBy.ID != "u1" {
+		t.Errorf("summary should carry the creating actor, got %q", list[1].CreatedBy.ID)
+	}
+}
+
+func TestSessionStoreListEmpty(t *testing.T) {
+	st := NewSessionStore(t.TempDir())
+	list, err := st.List()
+	if err != nil {
+		t.Fatalf("empty store should not error: %v", err)
+	}
+	if len(list) != 0 {
+		t.Errorf("expected no sessions, got %d", len(list))
+	}
+}

internal/api/ai_session_handlers.go

@@ -200,6 +200,26 @@ func (s *Server) getAISession(c *gin.Context) {
 	s.sessionResponse(c, sess)
 }
 
+// listAISessions returns the caller's saved sessions (all sessions for an admin),
+// most recent first, so past conversations can be resumed.
+func (s *Server) listAISessions(c *gin.Context) {
+	summaries, err := s.aiSessions.List()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	actor := auth.GetActorFromContext(c)
+	isAdmin := actor != nil && actor.Role == auth.RoleAdmin
+	mine := sessionActorFrom(c).ID
+	out := make([]ai.SessionSummary, 0, len(summaries))
+	for _, sum := range summaries {
+		if isAdmin || sum.CreatedBy.ID == mine {
+			out = append(out, sum)
+		}
+	}
+	c.JSON(http.StatusOK, gin.H{"sessions": out})
+}
+
 func (s *Server) postAISessionMessage(c *gin.Context) {
 	if !s.aiRequireEnabled(c) {
 		return

internal/api/ai_session_test.go

@@ -2,12 +2,15 @@ package api
 
 import (
 	"context"
+	"encoding/json"
 	"net/http"
 	"net/http/httptest"
 	"strings"
 	"testing"
 
 	"github.com/flatrun/agent/internal/ai"
+	"github.com/flatrun/agent/internal/auth"
+	"github.com/flatrun/agent/internal/contextkeys"
 	"github.com/flatrun/agent/pkg/models"
 	"github.com/gin-gonic/gin"
 )
@@ -308,3 +311,48 @@ func TestAIToolUnknownToolReported(t *testing.T) {
 		t.Errorf("unknown tool not reported: %q", result)
 	}
 }
+
+func TestListAISessionsFiltersByActor(t *testing.T) {
+	s, _, _ := setupPlanTestServer(t)
+
+	own := ai.NewSession(ai.SessionScopeSystem, "", true, ai.SessionActor{ID: "1", Name: "alice"}, "sys")
+	own.AddUserMessage("mine", "", false)
+	other := ai.NewSession(ai.SessionScopeSystem, "", true, ai.SessionActor{ID: "2", Name: "bob"}, "sys")
+	other.AddUserMessage("theirs", "", false)
+	if err := s.aiSessions.Save(own); err != nil {
+		t.Fatal(err)
+	}
+	if err := s.aiSessions.Save(other); err != nil {
+		t.Fatal(err)
+	}
+
+	call := func(actor *auth.ActorContext) []map[string]any {
+		w := httptest.NewRecorder()
+		c, _ := gin.CreateTestContext(w)
+		c.Request = httptest.NewRequest(http.MethodGet, "/ai/sessions", nil)
+		if actor != nil {
+			c.Set(contextkeys.Actor, actor)
+		}
+		s.listAISessions(c)
+		if w.Code != http.StatusOK {
+			t.Fatalf("status %d", w.Code)
+		}
+		var body struct {
+			Sessions []map[string]any `json:"sessions"`
+		}
+		if err := json.Unmarshal(w.Body.Bytes(), &body); err != nil {
+			t.Fatal(err)
+		}
+		return body.Sessions
+	}
+
+	mine := call(&auth.ActorContext{User: &auth.User{ID: 1, Username: "alice"}, Role: auth.RoleViewer})
+	if len(mine) != 1 || mine[0]["id"] != own.ID {
+		t.Errorf("a non-admin should see only their own sessions, got %v", mine)
+	}
+
+	all := call(&auth.ActorContext{User: &auth.User{ID: 9, Username: "root"}, Role: auth.RoleAdmin})
+	if len(all) != 2 {
+		t.Errorf("an admin should see all sessions, got %d", len(all))
+	}
+}

internal/api/server.go

@@ -502,6 +502,7 @@ func (s *Server) setupRoutes() {
 
 			// Interactive AI sessions (agentic tool loop)
 			protected.POST("/ai/sessions", s.authMiddleware.RequirePermission(auth.PermDeploymentsRead), s.createAISession)
+			protected.GET("/ai/sessions", s.authMiddleware.RequirePermission(auth.PermDeploymentsRead), s.listAISessions)
 			protected.GET("/ai/sessions/:id", s.getAISession)
 			protected.POST("/ai/sessions/:id/messages", s.postAISessionMessage)
 			protected.POST("/ai/sessions/:id/approve", s.approveAISessionTools)