feat: empty-container spawn (scratch workspace, no repo volume); fix bridge session isolation — explicit SessionManager per spawn stops SDK resuming the repo's old session (which also overrode LVMH_MODEL)

daemon/api.go

@@ -368,6 +368,7 @@ func (s *Server) handleSpawn(w http.ResponseWriter, r *http.Request) {
 		Repo   string `json:"repo"`
 		Branch string `json:"branch"`
 		Model  string `json:"model"`
+		Empty  bool   `json:"empty"`
 	}
 	if !decodeBody(w, r, &body) {
 		return
@@ -386,7 +387,7 @@ func (s *Server) handleSpawn(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "model must look like provider/model-id")
 		return
 	}
-	res, err := s.spawn.Start(r.Context(), body.Repo, body.Branch, body.Model)
+	res, err := s.spawn.Start(r.Context(), body.Repo, body.Branch, body.Model, body.Empty)
 	if err != nil {
 		writeError(w, http.StatusInternalServerError, err.Error())
 		return

daemon/docker.go

@@ -239,7 +239,7 @@ func (s *Spawner) deleteJob(sessionID string) {
 }
 
 // Start launches the async spawn pipeline and returns the new sessionId.
-func (s *Spawner) Start(ctx context.Context, repo, branch, model string) (SpawnResult, error) {
+func (s *Spawner) Start(ctx context.Context, repo, branch, model string, empty bool) (SpawnResult, error) {
 	exists, err := s.imageExists(ctx)
 	if err != nil {
 		return SpawnResult{}, fmt.Errorf("docker unavailable: %w", err)
@@ -253,7 +253,7 @@ func (s *Spawner) Start(ctx context.Context, repo, branch, model string) (SpawnR
 	}
 	sessionID := newUUID()
 	s.setJob(sessionID, repo, stateCloning, "", "")
-	go s.runJob(repo, branch, model, sessionID)
+	go s.runJob(repo, branch, model, empty, sessionID)
 	return SpawnResult{SessionID: sessionID, ImageUsed: s.resolveImage(repo)}, nil
 }
 
@@ -292,7 +292,7 @@ func (s *Spawner) slugLock(slug string) *sync.Mutex {
 }
 
 // runJob is the async clone→build→create→start pipeline.
-func (s *Spawner) runJob(repo, branch, model, sessionID string) {
+func (s *Spawner) runJob(repo, branch, model string, empty bool, sessionID string) {
 	slug := repoSlug(repo)
 	lock := s.slugLock(slug)
 	lock.Lock()
@@ -308,7 +308,7 @@ func (s *Spawner) runJob(repo, branch, model, sessionID string) {
 		return
 	}
 	s.setJob(sessionID, repo, stateCreating, "", "")
-	containerID, image, err := s.createAndStart(s.ctx, repo, slug, model, sessionID)
+	containerID, image, err := s.createAndStart(s.ctx, repo, slug, model, empty, sessionID)
 	if err != nil {
 		s.setJob(sessionID, repo, stateError, "", err.Error())
 		return
@@ -522,7 +522,7 @@ func extractBuildError(body []byte) string {
 // createAndStart provisions volumes, creates and starts the worker container.
 // A repo-registered custom image (see /api/repos) overrides the default
 // worker image; the ops agent builds and registers those.
-func (s *Spawner) createAndStart(ctx context.Context, repo, slug, model, sessionID string) (string, string, error) {
+func (s *Spawner) createAndStart(ctx context.Context, repo, slug, model string, empty bool, sessionID string) (string, string, error) {
 	image := s.resolveImage(repo)
 	if image != imageRefWorker {
 		exists, err := s.imageRefExists(ctx, image)
@@ -533,7 +533,12 @@ func (s *Spawner) createAndStart(ctx context.Context, repo, slug, model, session
 			return "", "", fmt.Errorf("custom image %s not built (ask the ops agent to build it)", image)
 		}
 	}
-	repoVolume := volumeRepoPrefix + slug
+	var repoVolume string
+	if empty {
+		// Scratch spawn: no repo, no shared workspace — a blank slate.
+		repoVolume = ""
+	} else {
+		repoVolume = volumeRepoPrefix + slug
 		fresh, err := s.ensureRepoVolume(ctx, repoVolume)
 		if err != nil {
 			return "", "", err
@@ -548,6 +553,7 @@ func (s *Spawner) createAndStart(ctx context.Context, repo, slug, model, session
 				return "", "", fmt.Errorf("seed %s: %w", repoVolume, err)
 			}
 		}
+	}
 	if _, err := s.cli.VolumeCreate(ctx, volume.CreateOptions{Name: volumeSessions}); err != nil {
 		return "", "", fmt.Errorf("volume %s: %w", volumeSessions, err)
 	}
@@ -555,11 +561,14 @@ func (s *Spawner) createAndStart(ctx context.Context, repo, slug, model, session
 		return "", "", fmt.Errorf("volume %s: %w", volumePiCache, err)
 	}
 
-	binds := []string{
+	var binds []string
-		repoVolume + ":" + workspaceMount,
+	if !empty {
+		binds = append(binds, repoVolume+":"+workspaceMount)
+	}
+	binds = append(binds,
 		volumeSessions+":"+sessionsMount,
 		volumePiCache+":"+cacheMount,
-	}
+	)
 	// Host pi credentials (OAuth tokens for anthropic etc.), read-only, so
 	// spawned agents can use every model the catalog offers.
 	if hostAgent := os.Getenv(envHostPiAgentDir); hostAgent != "" {

daemon/docker_test.go

@@ -495,7 +495,7 @@ func TestSpawnerSecretsBinds(t *testing.T) {
 	sec := t.TempDir()
 	t.Setenv(envSecretsDir, sec)
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -526,7 +526,7 @@ func TestWorkerBindsCaches(t *testing.T) {
 	t.Setenv(envPlaywrightCacheDir, "/host/pw")
 	t.Setenv(envCloakCacheDir, "/host/cb")
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}

daemon/spawner_test.go

@@ -29,7 +29,7 @@ func TestSpawnerStartHappyPath(t *testing.T) {
 	f := newFakeDocker()
 	sp, store := newTestSpawner(t, f)
 
-	res, err := sp.Start(context.Background(), "group/project", "main", "")
+	res, err := sp.Start(context.Background(), "group/project", "main", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -148,7 +148,7 @@ func TestSpawnerBuildsImageWhenMissing(t *testing.T) {
 	f.images = 0 // image absent → ensureImage must build
 	sp, _ := newTestSpawner(t, f)
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -172,7 +172,7 @@ func TestSpawnerStartValidatesDockerAndDockerfile(t *testing.T) {
 	if err != nil {
 		t.Fatalf("NewSpawner: %v", err)
 	}
-	_, err = sp2.Start(context.Background(), "group/project", "", "")
+	_, err = sp2.Start(context.Background(), "group/project", "", "", false)
 	if err == nil || !strings.Contains(err.Error(), "no worker Dockerfile") {
 		t.Fatalf("Start without dockerfile err = %v", err)
 	}
@@ -247,7 +247,7 @@ func TestSpawnerRunJobErrorStates(t *testing.T) {
 				tc.setup(t, f)
 			}
 			sp, _ := newTestSpawner(t, f)
-			res, err := sp.Start(context.Background(), "group/project", "", "")
+			res, err := sp.Start(context.Background(), "group/project", "", "", false)
 			if err != nil {
 				t.Fatalf("Start: %v", err)
 			}
@@ -384,11 +384,11 @@ func TestSpawnerSameRepoSpawnsSerialize(t *testing.T) {
 		t.Fatal("slugLock must return distinct mutexes per slug")
 	}
 
-	res1, err := sp.Start(context.Background(), "group/project", "", "")
+	res1, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start 1: %v", err)
 	}
-	res2, err := sp.Start(context.Background(), "group/project", "", "")
+	res2, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start 2: %v", err)
 	}
@@ -436,7 +436,7 @@ func TestSpawnerCloneUsesHeaderAuthNotURLCredentials(t *testing.T) {
 		t.Fatalf("set token: %v", err)
 	}
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -491,7 +491,7 @@ func TestSpawnerFailedSeedRemovesRepoVolume(t *testing.T) {
 	f.failArchive = true // CopyToContainer fails → seed fails
 	sp, _ := newTestSpawner(t, f)
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -514,7 +514,7 @@ func TestSpawnerFailedSeedSurvivesVolumeRemoveFailure(t *testing.T) {
 	f.failVolumeDelete = true // cleanup itself fails; seed error still surfaces
 	sp, _ := newTestSpawner(t, f)
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -722,7 +722,7 @@ func TestSpawnerStartDockerUnavailable(t *testing.T) {
 	// because the client is already built; close the fake server instead.
 	sp.cli.Close()
 	closeDocker(t, sp)
-	if _, err := sp.Start(context.Background(), "group/project", "", ""); err == nil || !strings.Contains(err.Error(), "docker unavailable") {
+	if _, err := sp.Start(context.Background(), "group/project", "", "", false); err == nil || !strings.Contains(err.Error(), "docker unavailable") {
 		t.Fatalf("Start with dead docker = %v, want docker unavailable", err)
 	}
 }
@@ -799,7 +799,7 @@ func TestSpawnerSessionsVolumeCreateFails(t *testing.T) {
 	f.volume[volumeRepoPrefix+repoSlug("group/project")] = true // repo volume exists → skip seed
 	f.failVolumeCreate = true
 	sp, _ := newTestSpawner(t, f)
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -844,7 +844,7 @@ func TestSpawnerStoreFailures(t *testing.T) {
 	dead2 := openTestStore(t)
 	_ = dead2.Close()
 	sp2.store = dead2
-	res, err := sp2.Start(context.Background(), "group/project", "", "")
+	res, err := sp2.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -877,7 +877,7 @@ func TestSpawnerWorkerCreateStartFailures(t *testing.T) {
 	sp, _ := newTestSpawner(t, f)
 
 	f.failCreate = true
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -887,7 +887,7 @@ func TestSpawnerWorkerCreateStartFailures(t *testing.T) {
 
 	f.failCreate = false
 	f.failStart = true
-	res2, err := sp.Start(context.Background(), "group/project", "", "")
+	res2, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start 2: %v", err)
 	}
@@ -906,7 +906,7 @@ func TestSpawnerBuildHTTPErrors(t *testing.T) {
 	f.images = 0
 	f.failBuildHTTP = true // /build endpoint itself 500s
 	sp, _ := newTestSpawner(t, f)
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -1186,7 +1186,7 @@ func TestSpawnerStartDedupesImageList(t *testing.T) {
 	useFakeGit(t, fakeGitModeOK)
 	f := newFakeDocker()
 	sp, _ := newTestSpawner(t, f)
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -1209,7 +1209,7 @@ func TestSpawnerCustomImageUsed(t *testing.T) {
 		t.Fatalf("set repo image: %v", err)
 	}
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -1238,7 +1238,7 @@ func TestSpawnerCustomImageMissing(t *testing.T) {
 		t.Fatalf("set repo image: %v", err)
 	}
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -1266,7 +1266,7 @@ func TestSpawnerCustomImageDeleteFallsBack(t *testing.T) {
 		t.Fatalf("delete repo image: %v", err)
 	}
 
-	res, err := sp.Start(context.Background(), "group/project", "", "")
+	res, err := sp.Start(context.Background(), "group/project", "", "", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -1287,7 +1287,7 @@ func TestSpawnerCustomImageCheckDockerDead(t *testing.T) {
 		t.Fatalf("set repo image: %v", err)
 	}
 	sp.images0AndDead(t)
-	_, _, err := sp.createAndStart(context.Background(), "group/project", repoSlug("group/project"), "", "s1")
+	_, _, err := sp.createAndStart(context.Background(), "group/project", repoSlug("group/project"), "", false, "s1")
 	if err == nil || !strings.Contains(err.Error(), "docker unavailable") {
 		t.Fatalf("createAndStart with dead docker = %v, want docker unavailable", err)
 	}
@@ -1298,7 +1298,7 @@ func TestSpawnerModelEnv(t *testing.T) {
 	f := newFakeDocker()
 	sp, _ := newTestSpawner(t, f)
 
-	res, err := sp.Start(context.Background(), "group/project", "", "zai-renaud/glm-5.2")
+	res, err := sp.Start(context.Background(), "group/project", "", "zai-renaud/glm-5.2", false)
 	if err != nil {
 		t.Fatalf("Start: %v", err)
 	}
@@ -1317,3 +1317,34 @@ func TestSpawnerModelEnv(t *testing.T) {
 		t.Fatalf("LVMH_MODEL missing from %v", creates[0].Env)
 	}
 }
+
+func TestSpawnerEmptyScratch(t *testing.T) {
+	useFakeGit(t, fakeGitModeOK)
+	f := newFakeDocker()
+	sp, _ := newTestSpawner(t, f)
+
+	res, err := sp.Start(context.Background(), "group/project", "", "", true)
+	if err != nil {
+		t.Fatalf("Start: %v", err)
+	}
+	waitJobState(t, sp, res.SessionID, stateRunning)
+	creates := f.createsByName("lvmh-agent-")
+	if len(creates) != 1 {
+		t.Fatalf("creates = %d", len(creates))
+	}
+	binds := creates[0].HostConfig.Binds
+	for _, b := range binds {
+		if b == "lvmh-repo-group--project-ab12cd:/workspace" {
+			t.Fatalf("empty spawn must not mount the repo volume: %v", binds)
+		}
+	}
+	hasSessions := false
+	for _, b := range binds {
+		if b == "lvmh-sessions:/pi-sessions" {
+			hasSessions = true
+		}
+	}
+	if !hasSessions {
+		t.Fatalf("sessions volume missing: %v", binds)
+	}
+}

docker/bridge/index.mjs

@@ -7,6 +7,7 @@ import { existsSync } from "node:fs";
 import {
 	createAgentSession,
 	ModelRuntime,
+	SessionManager,
 } from "/usr/local/lib/node_modules/@earendil-works/pi-coding-agent/dist/index.js";
 
 const SETUP_PATH = "/workspace/.lvmh/setup.sh";
@@ -85,8 +86,15 @@ try {
 			console.error(`[lvmh-bridge] model resolution failed:`, err);
 		}
 	}
+	// Fresh session per spawn: without an explicit sessionManager the SDK
+	// picks up an existing session file for the cwd — sharing one transcript
+	// (and its saved model) across every spawn of the repo. A dedicated dir
+	// per daemon session id keeps spawns isolated and LVMH_MODEL authoritative.
+	const sessionRoot = process.env.PI_SESSION_DIR ?? "/pi-sessions";
+	const sessionDir = `${sessionRoot}/${process.env.LVMH_SESSION_ID ?? "default"}`;
+	const sessionManager = SessionManager.create(process.cwd(), sessionDir);
 	const { session } = await createAgentSession(
-		model === undefined ? {} : { model },
+		model === undefined ? { sessionManager } : { model, sessionManager },
 	);
 	// SDK does not bind extensions implicitly (unlike TUI/RPC modes); without
 	// bindExtensions the session_start event never fires, so the lvmh plugin

web/src/SpawnView.test.tsx

@@ -715,3 +715,28 @@ describe("spawn model selection", () => {
 		expect(bodies[0]).toContain('"model":"zai-renaud/glm-5.3"');
 	});
 });
+
+describe("empty container spawn", () => {
+	it("checkbox sends empty:true and resets after", async () => {
+		const bodies: string[] = [];
+		mockFetchJson((url, init) => {
+			if (init?.method === "POST" && url.endsWith("/api/spawn")) {
+				bodies.push(String(init.body));
+				return { sessionId: "e1", imageUsed: "lvmh-worker:latest" };
+			}
+			if (url.endsWith("/api/gitlab/status"))
+				return { connected: true, baseUrl: "https://gl", username: "a" };
+			if (url.endsWith("/api/gitlab/repos")) return [repo("g/p")];
+			return [];
+		});
+		render(tree(makeStore()));
+		await flush();
+		fireEvent.click(screen.getByText("g/p"));
+		const cb = screen.getByRole("checkbox");
+		fireEvent.click(cb);
+		expect(cb).toBeChecked();
+		fireEvent.click(screen.getByLabelText("Spawn container"));
+		await flush();
+		expect(bodies[0]).toContain('"empty":true');
+	});
+});

web/src/SpawnView.tsx

@@ -61,6 +61,7 @@ export default function SpawnView({ store, pushToast }: Props) {
 	const [query, setQuery] = useState<string>("");
 	const [selected, setSelected] = useState<Repo | null>(null);
 	const [branch, setBranch] = useState<string>("");
+	const [empty, setEmpty] = useState<boolean>(false);
 	const [model, setModel] = useState<string>("");
 	const [catalog, setCatalog] = useState<ModelCatalogEntry[] | null>(null);
 	const [busy, setBusy] = useState<boolean>(false);
@@ -176,6 +177,7 @@ export default function SpawnView({ store, pushToast }: Props) {
 				repo: selected!.path,
 				...(branch.trim().length > 0 ? { branch: branch.trim() } : {}),
 				...(model.length > 0 ? { model } : {}),
+				...(empty ? { empty: true } : {}),
 			};
 			const res = await fetchJson<SpawnResponse>(Route.Spawn, {
 				method: "POST",
@@ -429,6 +431,18 @@ export default function SpawnView({ store, pushToast }: Props) {
 									))}
 							</select>
 						</div>
+						<label
+							className="repo-meta"
+							style={{ marginTop: 8, display: "flex", gap: 6, alignItems: "center" }}
+						>
+							<input
+								type="checkbox"
+								checked={empty}
+								onChange={(e) => setEmpty(e.target.checked)}
+								disabled={busy}
+							/>
+							Empty container (no repo — blank workspace)
+						</label>
 						{error.length > 0 && <p className="error-text">{error}</p>}
 					</div>
 				</>