feat(maestro): mirror activity_since and Error state in web types

Pressing Spawn while reading a session split that pane in half. It now
opens the draft in its own tab, leaving the current tab untouched.

Scoped to the explicit Spawn affordances (the header button and the
sidebar empty state, both via OPEN_SPAWN_EVENT). "Spawn similar" and the
fast-forward key deliberately keep splitting: both act on the session in
front of you, so a pane beside it is the point. Reusing an empty pane
(#72) is unchanged — that path never split anything.

Closes #100

.gitea/workflows/ci.yml

@@ -106,14 +106,24 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      # The runner container is root with no `nixbld` group, but the installer
+      # writes `build-users-group = nixbld` anyway and then fails on it, so the
+      # config goes in first. Flakes are off by default and `nix build .#…`
+      # needs them. Written again afterwards in case the installer replaced it.
       - name: Install nix
         run: |
-          curl -fsSL https://nixos.org/nix/install | sh -s -- --daemon --yes
-          echo "/nix/var/nix/profiles/default/bin" >> "$GITHUB_PATH"
+          mkdir -p /etc/nix
+          printf 'build-users-group =\nexperimental-features = nix-command flakes\n' > /etc/nix/nix.conf
+          curl -fsSL https://nixos.org/nix/install | sh -s -- --no-daemon --yes
+          printf 'build-users-group =\nexperimental-features = nix-command flakes\n' > /etc/nix/nix.conf
+          echo "$HOME/.nix-profile/bin" >> "$GITHUB_PATH"
 
+      # The installer does not enable flakes, so `nix build .#…` needs the
+      # features passed explicitly — a local machine that has them in
+      # nix.conf will build fine while CI fails without this.
       - name: build flake packages
         run: |
-          nix build \
+          nix --extra-experimental-features "nix-command flakes" build \
             .#webFrontend \
             .#maestro \
             .#maestro-web \

crates/maestro-cli/src/sessions.rs

@@ -108,6 +108,7 @@ fn print_session_table(out: &mut impl Write, sessions: &[Session], info: &Daemon
             ActivityState::Active => "active",
             ActivityState::Idle => "idle",
             ActivityState::AwaitingInput => "awaiting",
+            ActivityState::Error => "error",
         };
         // Show the live foreground command alongside the spawn command when
         // the daemon has observed one that differs (NAP-340).
@@ -176,6 +177,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
             current_cwd: None,
             blocked_work: None,
         }

crates/maestro-daemon/src/session.rs

@@ -278,7 +278,11 @@ impl SessionManager {
                     self.inner.worktree_mgr.add_existing(base_repo, branch)
                 }
                 .map_err(SessionError::Worktree)?;
-                (path.clone(), Some(path), Some(base_repo.clone()))
+                // Record the repository, not whatever the request named: a
+                // spawn from inside a linked worktree passes that worktree as
+                // `base_repo`, and clients group sessions by this path (#99).
+                let repo = crate::worktree::main_checkout_of(base_repo);
+                (path.clone(), Some(path), Some(repo))
             }
             None => (req.cwd.clone(), None, None),
         };
@@ -349,6 +353,7 @@ impl SessionManager {
             foreground: None,
             activity: ActivityState::Active,
             last_activity_at: Utc::now(),
+            activity_since: chrono::Utc::now(),
 
             current_cwd: None,
             // The watcher fills this in on its first blocked-work pass; a
@@ -568,6 +573,7 @@ impl SessionManager {
                     foreground: None,
                     activity: ActivityState::Idle,
                     last_activity_at: Utc::now(),
+                    activity_since: chrono::Utc::now(),
 
                     current_cwd: None,
                     blocked_work: None,

crates/maestro-daemon/src/worktree.rs

@@ -174,6 +174,13 @@ impl WorktreeManager {
 /// The repository's main checkout. `--git-common-dir` points at the shared
 /// `.git` for every linked worktree, so its parent is the main tree. Falls
 /// back to the input when git can't answer.
+/// The repository a path belongs to: the main checkout, even when `path` is a
+/// linked worktree. Clients group sessions by this (#99), and placement uses it
+/// so a worktree is never nested inside another.
+pub fn main_checkout_of(path: &Path) -> PathBuf {
+    main_checkout(path)
+}
+
 fn main_checkout(path: &Path) -> PathBuf {
     let out = Command::new("git")
         .arg("-C")

crates/maestro-daemon/tests/session_manager.rs

@@ -947,3 +947,60 @@ async fn liveness_watcher_leaves_running_sessions_alone() {
 
     fx.manager.kill(s.id, false).await.unwrap();
 }
+
+/// #99: clients group a session under `worktree.base_repo`, so that field has
+/// to name the repository even when the spawn request pointed at a linked
+/// worktree. Recording the request verbatim put the session in a folder of its
+/// own — `<repo>/worktrees/<branch>` — instead of under the repo.
+#[tokio::test]
+async fn worktree_base_repo_records_the_main_checkout_not_the_request() {
+    let fx = DaemonFixture::new();
+    let repo = TempDir::new().unwrap();
+    init_repo(repo.path());
+
+    // A linked worktree of that repo, then a spawn whose `base_repo` names it
+    // rather than the main checkout — what happens when the operator spawns
+    // from inside a worktree.
+    let first = fx
+        .manager
+        .create(CreateSessionRequest {
+            cwd: repo.path().to_path_buf(),
+            command: "sleep 30".into(),
+            env: HashMap::new(),
+            metadata: HashMap::new(),
+            worktree: Some(WorktreeSpec {
+                base_repo: repo.path().to_path_buf(),
+                branch: "feat/one".into(),
+                create_branch: true,
+            }),
+        })
+        .await
+        .expect("create first");
+    let inner_worktree = first.worktree.expect("first has a worktree").path;
+
+    let second = fx
+        .manager
+        .create(CreateSessionRequest {
+            cwd: inner_worktree.clone(),
+            command: "sleep 30".into(),
+            env: HashMap::new(),
+            metadata: HashMap::new(),
+            worktree: Some(WorktreeSpec {
+                base_repo: inner_worktree.clone(),
+                branch: "feat/two".into(),
+                create_branch: true,
+            }),
+        })
+        .await
+        .expect("create second");
+
+    let wt = second.worktree.expect("second has a worktree");
+    assert_eq!(
+        wt.base_repo,
+        repo.path()
+            .canonicalize()
+            .unwrap_or_else(|_| repo.path().to_path_buf()),
+        "base_repo must be the repository, not the worktree the request named",
+    );
+    assert_ne!(wt.base_repo, inner_worktree, "the worktree is not the repo");
+}

crates/maestro-daemon/tests/sidecar.rs

@@ -27,6 +27,7 @@ fn sample(id: Uuid) -> Session {
         foreground: None,
         activity: Default::default(),
         last_activity_at: chrono::Utc::now(),
+        activity_since: chrono::Utc::now(),
         current_cwd: Some(PathBuf::from("/tmp/work/crates")),
         blocked_work: None,
     }

crates/maestro-protocol/src/lib.rs

@@ -80,6 +80,13 @@ pub struct Session {
     /// from daemons that predate the field.
     #[serde(default = "epoch")]
     pub last_activity_at: DateTime<Utc>,
+    /// Wall-clock time at which the session entered its current
+    /// [`ActivityState`] (#102) — how long it has been `Active`, `Idle` or
+    /// `AwaitingInput`. Distinct from [`Self::last_activity_at`], which only
+    /// tracks the last observed PTY output. Populated by #104; defaults to the
+    /// Unix epoch on payloads from daemons that predate the field.
+    #[serde(default = "epoch")]
+    pub activity_since: DateTime<Utc>,
     /// The pane's *current* working directory (`#{pane_current_path}`) — distinct
     /// from [`Session::cwd`], the directory it was spawned in. The activity
     /// watcher refreshes it as the user `cd`s around; it drives the web UI's
@@ -119,6 +126,9 @@ pub enum ActivityState {
     Idle,
     /// Blocked on a `read()` from the pty — waiting on the user.
     AwaitingInput,
+    /// The agent running in the session reported a failure (#102). Never
+    /// inferred by the daemon; only set when an agent reports it (#105).
+    Error,
 }
 
 /// Optional worktree request attached to a `CreateSessionRequest`.
@@ -537,6 +547,9 @@ mod tests {
             last_activity_at: DateTime::parse_from_rfc3339("2026-05-24T12:05:00Z")
                 .unwrap()
                 .with_timezone(&Utc),
+            activity_since: DateTime::parse_from_rfc3339("2026-05-24T12:04:30Z")
+                .unwrap()
+                .with_timezone(&Utc),
             current_cwd: Some(PathBuf::from("/home/naps62/projects/maestro/crates")),
             blocked_work: None,
         }
@@ -588,6 +601,35 @@ mod tests {
         );
     }
 
+    #[test]
+    fn activity_since_defaults_to_epoch_on_legacy_payload() {
+        // A daemon predating #102 omits `activity_since`; it must deserialize
+        // to the forward-compat default rather than failing, and a present
+        // value round-trips.
+        let json = serde_json::json!({
+            "id": Uuid::from_u128(1),
+            "cwd": "/tmp",
+            "command": "bash",
+            "status": "Running",
+            "created_at": "2026-05-24T12:00:00Z"
+        });
+        let s: Session = serde_json::from_value(json).unwrap();
+        assert_eq!(s.activity_since, epoch());
+
+        let full = sample_session();
+        assert_eq!(full, round_trip(&full));
+    }
+
+    // #102: nothing infers `Error`; only #105's agent-reported failure sets it.
+    #[test]
+    fn error_activity_state_serializes_pascal_case_and_idle_stays_default() {
+        assert_eq!(
+            serde_json::to_value(ActivityState::Error).unwrap(),
+            serde_json::json!("Error")
+        );
+        assert_eq!(ActivityState::default(), ActivityState::Idle);
+    }
+
     #[test]
     fn activity_state_serializes_pascal_case_and_defaults_idle() {
         assert_eq!(

crates/maestro-testing/src/lib.rs

@@ -42,6 +42,7 @@ pub fn session(id: Uuid, cwd: &str, command: &str) -> Session {
         foreground: None,
         activity: Default::default(),
         last_activity_at: Utc::now(),
+        activity_since: chrono::Utc::now(),
         current_cwd: None,
         blocked_work: None,
     }

crates/maestro-tui/src/app.rs

@@ -1127,6 +1127,7 @@ mod tests {
                 foreground: None,
                 activity: Default::default(),
                 last_activity_at: Utc::now(),
+                activity_since: chrono::Utc::now(),
                 current_cwd: None,
                 blocked_work: None,
             }],
@@ -1644,6 +1645,7 @@ mod tests {
                 foreground: None,
                 activity: Default::default(),
                 last_activity_at: chrono::Utc::now(),
+                activity_since: chrono::Utc::now(),
 
                 current_cwd: None,
                 blocked_work: None,

crates/maestro-tui/src/catalog.rs

@@ -194,6 +194,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
             current_cwd: None,
             blocked_work: None,
         }

crates/maestro-tui/src/draft.rs

@@ -199,6 +199,12 @@ pub struct DraftPane {
     /// Highlighted entry within the visible step-one list; the implicit
     /// `Other directory…` entry sits at index `visible_groups().len()`.
     pub highlighted: usize,
+    /// Set by an explicit Up/Down move, cleared by typing (#97): typing
+    /// mirrors the web form's plain filter input, where Enter always
+    /// resolves and submits; an explicit arrow move mirrors Tab landing on
+    /// a not-yet-active picker button there, where a first Enter only
+    /// chooses. See `dir_picker_choice_active` at the Enter match arm.
+    dir_picker_navigated: bool,
     pub cwd_raw_visible: bool,
     pub cwd_raw: crate::text_input::TextInput,
     pub picked_cwd: Option<PathBuf>,
@@ -270,6 +276,7 @@ impl Default for DraftPane {
             groups: Vec::new(),
             filter: crate::text_input::TextInput::default(),
             highlighted: 0,
+            dir_picker_navigated: false,
             cwd_raw_visible: false,
             cwd_raw: crate::text_input::TextInput::default(),
             picked_cwd: None,
@@ -769,6 +776,7 @@ impl DraftPane {
         if count == 0 {
             return;
         }
+        self.dir_picker_navigated = true;
         self.highlighted = ((self.selection() as i32) + delta).rem_euclid(count) as usize;
     }
 
@@ -804,6 +812,17 @@ impl DraftPane {
         rows
     }
 
+    /// Whether the highlighted step-one row is already the picked group
+    /// (#97): once true, a further Enter submits instead of re-picking it.
+    /// Always false on the trailing "Other directory…" row — picking it is
+    /// never a no-op, so it always takes the Enter to reveal the raw field.
+    fn dir_picker_choice_active(&self) -> bool {
+        let visible = self.visible_groups();
+        let sel = self.selection();
+        sel < visible.len()
+            && self.selected_group_key.as_ref() == Some(&group_key(&visible[sel].main))
+    }
+
     /// Act on the highlighted step-one box: reveals step two, defaulting per
     /// rule 4. The trailing entry reveals the free-text path input and
     /// clears both steps (rule 3).
@@ -933,27 +952,33 @@ impl DraftPane {
                 self.prev_field();
                 DraftInputResult::Consumed
             }
-            InputKey::Enter => match self.focused_field {
-                DraftField::Submit => DraftInputResult::Submit,
-                DraftField::DirPicker => {
-                    self.select_entry();
+            // Enter submits from any field (#97), mirroring web/src/spawnForm.ts.
+            // Two fields keep their own Enter instead: `DirPicker`, whose
+            // highlighted row isn't the picked one until a first Enter chooses
+            // it (the next Enter, now that it's active, falls through to
+            // submit); and the disclosure/toggle pair (`Advanced`,
+            // `WorktreeToggle`), which activate on Enter like a button rather
+            // than submitting, same as the web form's own `<button>` controls.
+            InputKey::Enter if self.focused_field == DraftField::DirPicker => {
+                let is_other_row = self.selection() >= self.visible_groups().len();
+                let choose_only =
+                    is_other_row || (self.dir_picker_navigated && !self.dir_picker_choice_active());
+                self.select_entry();
+                if choose_only {
                     DraftInputResult::Consumed
+                } else {
+                    DraftInputResult::Submit
                 }
-                DraftField::Advanced => {
-                    self.toggle_advanced();
-                    DraftInputResult::Consumed
-                }
-                DraftField::WorktreeToggle => {
-                    self.toggle_worktree();
-                    DraftInputResult::Consumed
-                }
-                // The existing-branch selection is live; Enter just confirms.
-                DraftField::BranchExisting => DraftInputResult::Consumed,
-                _ => {
-                    self.next_field();
-                    DraftInputResult::Consumed
-                }
-            },
+            }
+            InputKey::Enter if self.focused_field == DraftField::Advanced => {
+                self.toggle_advanced();
+                DraftInputResult::Consumed
+            }
+            InputKey::Enter if self.focused_field == DraftField::WorktreeToggle => {
+                self.toggle_worktree();
+                DraftInputResult::Consumed
+            }
+            InputKey::Enter => DraftInputResult::Submit,
             InputKey::Char {
                 c: ' ',
                 ctrl: false,
@@ -1025,6 +1050,7 @@ impl DraftPane {
                     DraftField::DirPicker => {
                         self.filter.handle_key(other);
                         self.highlighted = 0;
+                        self.dir_picker_navigated = false;
                     }
                     DraftField::CwdRaw => {
                         self.cwd_raw.handle_key(other);
@@ -1748,7 +1774,11 @@ mod tests {
             1,
             "type-to-filter narrows the list"
         );
-        draft.on_input(&InputKey::Enter);
+        assert_eq!(
+            draft.on_input(&InputKey::Enter),
+            DraftInputResult::Submit,
+            "#97: the project filter submits with the highlighted project in one Enter"
+        );
         assert_eq!(
             draft.picked_cwd.as_deref(),
             Some(Path::new("/repos/maestro"))
@@ -1760,6 +1790,113 @@ mod tests {
         );
     }
 
+    #[test]
+    fn enter_submits_immediately_from_ordinary_fields_97() {
+        let mut draft = DraftPane {
+            picked_cwd: Some(PathBuf::from("/repos/maestro")),
+            base_repo: Some(PathBuf::from("/repos/maestro")),
+            probed_cwd: Some(PathBuf::from("/repos/maestro")),
+            ..DraftPane::default()
+        };
+
+        for field in [
+            DraftField::Preset,
+            DraftField::Name,
+            DraftField::BranchNew,
+            DraftField::BranchMode,
+        ] {
+            draft.focused_field = field;
+            assert_eq!(
+                draft.on_input(&InputKey::Enter),
+                DraftInputResult::Submit,
+                "{field:?} should submit on Enter"
+            );
+        }
+
+        draft.selected_preset = draft.presets.len() - 1; // custom
+        draft.focused_field = DraftField::CustomCommand;
+        assert_eq!(draft.on_input(&InputKey::Enter), DraftInputResult::Submit);
+    }
+
+    #[test]
+    fn enter_submits_immediately_from_eager_apply_pickers_97() {
+        // WorktreeChoice and BranchExisting apply their highlight the moment
+        // Up/Down moves it (#96 rule 3/#54) — there is no separate "chosen
+        // vs highlighted" state left to confirm, so Enter always submits.
+        let mut draft = DraftPane::default();
+        draft.set_projects(
+            vec![repo_project(
+                "maestro",
+                "/repos/maestro",
+                "/repos/maestro",
+                1,
+                None,
+            )],
+            Utc::now(),
+        );
+        draft.focused_field = DraftField::DirPicker;
+        draft.on_input(&InputKey::Enter); // picks "maestro", reveals step two
+
+        draft.focused_field = DraftField::WorktreeChoice;
+        assert_eq!(draft.on_input(&InputKey::Enter), DraftInputResult::Submit);
+
+        draft.focused_field = DraftField::BranchExisting;
+        assert_eq!(draft.on_input(&InputKey::Enter), DraftInputResult::Submit);
+    }
+
+    #[test]
+    fn dir_picker_enter_chooses_then_submits_once_the_highlight_is_the_active_pick_97() {
+        let mut draft = DraftPane::default();
+        draft.set_projects(
+            vec![
+                project("maestro", "/repos/maestro", 1, Some("claude")),
+                project("other", "/repos/other", 2, Some("zsh")),
+            ],
+            Utc::now(),
+        );
+        draft.focused_field = DraftField::DirPicker;
+        draft.on_input(&InputKey::Enter); // picks "maestro" (nothing chosen yet, submits)
+        assert_eq!(
+            draft.picked_cwd.as_deref(),
+            Some(Path::new("/repos/maestro"))
+        );
+
+        // Arrow onto the other row: an explicit navigation away from the
+        // active pick is "mid-selection" — Enter here only chooses it.
+        draft.move_selection(1);
+        assert_eq!(
+            draft.on_input(&InputKey::Enter),
+            DraftInputResult::Consumed,
+            "navigating to a different row must not submit the old pick"
+        );
+        assert_eq!(
+            draft.picked_cwd.as_deref(),
+            Some(Path::new("/repos/other")),
+            "the new row is chosen"
+        );
+
+        // The highlight is now the active pick: the next Enter submits.
+        assert_eq!(draft.on_input(&InputKey::Enter), DraftInputResult::Submit);
+    }
+
+    #[test]
+    fn dir_picker_enter_on_other_directory_never_submits_directly_97() {
+        let mut draft = DraftPane::default();
+        draft.set_projects(
+            vec![project("maestro", "/repos/maestro", 1, None)],
+            Utc::now(),
+        );
+        draft.focused_field = DraftField::DirPicker;
+        draft.move_selection(1); // onto "Other directory…"
+
+        assert_eq!(
+            draft.on_input(&InputKey::Enter),
+            DraftInputResult::Consumed,
+            "reveals the raw field instead of submitting, like the web form's own button"
+        );
+        assert_eq!(draft.focused_field, DraftField::CwdRaw);
+    }
+
     #[test]
     fn up_down_moves_the_highlight_within_the_list() {
         let mut draft = DraftPane::default();

crates/maestro-tui/src/sidebar.rs

@@ -105,6 +105,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
             current_cwd: None,
             blocked_work: None,
         }
@@ -228,6 +229,7 @@ mod tests {
             foreground: None,
             activity: Default::default(),
             last_activity_at: chrono::Utc::now(),
+            activity_since: chrono::Utc::now(),
 
             current_cwd: None,
             blocked_work: None,

web/src/main.ts

@@ -272,7 +272,11 @@ function showMultiView(): void {
 // cloned session's dir + command.
 function requestOpenSpawn(): void {
   showMultiView();
-  mv.openDraft();
+  // A new tab, not a split of the pane you were reading (#100). "Spawn
+  // similar" and the fast-forward key below deliberately keep the old
+  // behaviour: both act on the session in front of you, so a split beside it
+  // is the point.
+  mv.openDraft(undefined, { newTab: true });
 }
 document.addEventListener(OPEN_SPAWN_EVENT, () => requestOpenSpawn());
 document.addEventListener("catalog-spawn-similar", (ev) => {

web/src/multiview.test.ts

@@ -282,3 +282,54 @@ describe("multiview pane-drag swap (#73)", () => {
     expect(nameInputOf(leaf2).value).toBe("west");
   });
 });
+
+describe("openDraft newTab (#100)", () => {
+  beforeEach(() => {
+    stubFetch();
+    document.body.replaceChildren();
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("opens its own tab instead of splitting the focused session", async () => {
+    const layout = emptyLayout();
+    const tab = layout.tabs[0];
+    const first = splitLeaf(tab, "", "s1", "row", true);
+    tab.focusedLeafId = first;
+    const mv = makeMv(layout);
+    document.body.appendChild(mv.el);
+    mv.render();
+
+    mv.openDraft(undefined, { newTab: true });
+    await flush();
+
+    expect(layout.tabs).toHaveLength(2);
+    // The tab you were reading is untouched: still one pane, still its session.
+    const original = leaves(layout.tabs[0].root);
+    expect(original).toHaveLength(1);
+    expect(original[0].sessionId).toBe("s1");
+    // The draft is alone in the new, now-active tab.
+    const fresh = leaves(layout.tabs[1].root);
+    expect(fresh).toHaveLength(1);
+    expect(fresh[0].sessionId).toBeNull();
+    expect(fresh[0].draft).not.toBeNull();
+    expect(layout.activeTabId).toBe(layout.tabs[1].id);
+  });
+
+  it("still splits when newTab is not asked for", async () => {
+    const layout = emptyLayout();
+    const tab = layout.tabs[0];
+    tab.focusedLeafId = splitLeaf(tab, "", "s1", "row", true);
+    const mv = makeMv(layout);
+    document.body.appendChild(mv.el);
+    mv.render();
+
+    mv.openDraft();
+    await flush();
+
+    expect(layout.tabs).toHaveLength(1);
+    expect(leaves(tab.root)).toHaveLength(2);
+  });
+});

web/src/multiview.ts

@@ -57,7 +57,7 @@ export interface MultiView {
   /** Open a draft pane (issue #62): reuse the focused pane if it is already
    *  empty, otherwise split the focused pane. `seed` pre-fills the form
    *  ("Spawn similar" clones a session's cwd + command). */
-  openDraft: (seed?: Partial<Draft>) => void;
+  openDraft: (seed?: Partial<Draft>, opts?: { newTab?: boolean }) => void;
   /** Start dragging a sidebar session into the canvas (issue #32). The
    *  controller owns drag-vs-tap: a tap lets the row's normal click open it, a
    *  drag shows drop zones to place it. */
@@ -412,9 +412,18 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
     opts.onOpenSessionsChange?.();
   }
 
-  function openDraft(seed?: Partial<Draft>): void {
-    const tab = activeTab(layout);
+  function openDraft(seed?: Partial<Draft>, opts?: { newTab?: boolean }): void {
     const draft = (): Draft => ({ command: "", cwd: "", name: "", ...seed });
+    if (opts?.newTab) {
+      // Spawn opens its own tab rather than halving whatever you were reading
+      // (#100). The empty-pane reuse below still applies within a tab.
+      const fresh = addTab(layout);
+      fresh.focusedLeafId = splitLeaf(fresh, "", null, "row", true);
+      findLeaf(fresh.root!, fresh.focusedLeafId)!.draft = draft();
+      render();
+      return;
+    }
+    const tab = activeTab(layout);
     if (!tab.root || !tab.focusedLeafId || !findLeaf(tab.root, tab.focusedLeafId)) {
       // Empty tab (or stale focus): the draft becomes the first pane.
       tab.focusedLeafId = splitLeaf(tab, "", null, "row", true);

web/src/spawnForm.ts

@@ -549,11 +549,15 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
     if (match) selectPreset(match.id);
   }
 
+  /** Groups with at least one member (itself or a worktree) matching `query`. */
+  function visibleGroups(query: string): ProjectGroup[] {
+    return groups.filter((g) => filterProjects([g.main, ...g.worktrees], query).length > 0);
+  }
+
   function renderProjects(): void {
     projectsEl.replaceChildren();
     groups = groupProjects(sortProjects(discovered, new Date()));
-    const query = filterInput.value;
-    const visible = groups.filter((g) => filterProjects([g.main, ...g.worktrees], query).length > 0);
+    const visible = visibleGroups(filterInput.value);
     for (const group of visible) projectsEl.appendChild(projectBox(group));
     if (discovered.length > 0 && visible.length === 0) {
       const empty = document.createElement("p");
@@ -862,6 +866,43 @@ export function createSpawnForm(opts: SpawnFormOptions): SpawnFormHandle {
   // ---- live dir autocomplete on the raw cwd input (NAP-329) ------------
   const autocomplete = attachDirAutocomplete(cwdRaw);
 
+  // ---- Enter submits from anywhere (#97) --------------------------------
+  // A project-box/wt-choice that isn't yet the active pick takes the Enter to
+  // choose it instead; the next Enter, now that it's active, submits.
+  // dirAutocomplete's own Enter (accept the highlight) already preventDefaults
+  // when it handles the key, which the `e.defaultPrevented` guard defers to.
+  // The worktree checkbox keeps Enter as a toggle (TUI parity: `WorktreeToggle`
+  // does the same) rather than folding it into the blanket-submit rule below.
+  form.addEventListener("keydown", (e) => {
+    if (e.key !== "Enter" || e.defaultPrevented) return;
+    const target = e.target as HTMLElement;
+
+    if (target === wtEnabled) {
+      e.preventDefault();
+      wtEnabled.checked = !wtEnabled.checked;
+      wtEnabled.dispatchEvent(new Event("change"));
+      return;
+    }
+
+    if (target instanceof HTMLButtonElement) {
+      if (!target.classList.contains("project-box") && !target.classList.contains("wt-choice")) return;
+      e.preventDefault();
+      if (!target.classList.contains("is-active")) {
+        target.click();
+        return;
+      }
+      form.requestSubmit();
+      return;
+    }
+
+    e.preventDefault();
+    if (target === filterInput) {
+      const top = visibleGroups(filterInput.value)[0];
+      if (top && top.main.path !== selectedGroup?.main.path) selectProject(top);
+    }
+    form.requestSubmit();
+  });
+
   // ---- submit ----------------------------------------------------------
   form.addEventListener("submit", async (e) => {
     e.preventDefault();

web/src/spawnFormEnter.test.ts

@@ -0,0 +1,258 @@
+// @vitest-environment happy-dom
+// Enter submits the draft form from any field, at any point (#97). The two
+// exceptions: a picker button that isn't yet the active choice takes the
+// Enter to *choose* it instead (the next Enter submits), and the project
+// filter must resolve to the highlighted project rather than sending
+// whatever cwd was already set.
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { createSpawnForm, type SpawnFormHandle } from "./spawnForm.js";
+import type { Project } from "./types.js";
+
+const MAESTRO: Project = {
+  path: "/home/user/tea/maestro",
+  name: "maestro",
+  is_worktree: false,
+  last_activity: "2026-08-20T10:00:00Z",
+};
+
+const WT_A: Project = {
+  path: "/home/user/tea/maestro/worktrees/bulgarians",
+  name: "bulgarians",
+  is_worktree: true,
+  base_repo: MAESTRO.path,
+  last_activity: "2026-08-22T10:00:00Z",
+};
+
+const OTHER: Project = {
+  path: "/home/user/tea/rev",
+  name: "rev",
+  is_worktree: false,
+  last_activity: "2026-08-19T10:00:00Z",
+};
+
+function stubFetch(projects: Project[]): void {
+  vi.stubGlobal(
+    "fetch",
+    vi.fn(async (input: RequestInfo | URL) => {
+      const url = String(input);
+      const body = url.includes("/api/projects")
+        ? projects
+        : url.includes("/api/names")
+          ? { names: ["amber-fox"] }
+          : url.includes("/api/branches")
+            ? []
+            : url.includes("/api/dirs")
+              ? { path: "/opt", entries: ["nomatch-zzz"], truncated: false }
+              : { hostname: "h", version: "0", home_dir: "/home/user", presets: [] };
+      return new Response(JSON.stringify(body), { status: 200 });
+    }),
+  );
+}
+
+describe("spawnForm Enter-to-submit (#97)", () => {
+  let handle: SpawnFormHandle | null = null;
+
+  beforeEach(() => {
+    vi.useFakeTimers({ now: Date.parse("2026-08-23T12:00:00Z") });
+  });
+
+  afterEach(() => {
+    handle?.destroy();
+    handle = null;
+    vi.unstubAllGlobals();
+    vi.useRealTimers();
+  });
+
+  const drain = async () => {
+    for (let i = 0; i < 40; i++) await Promise.resolve();
+  };
+
+  async function mount(projects: Project[]): Promise<HTMLFormElement> {
+    stubFetch(projects);
+    handle = createSpawnForm({ onSuccess() {} });
+    document.body.appendChild(handle.el);
+    await drain();
+    return handle.el;
+  }
+
+  function submitSpy(): ReturnType<typeof vi.fn> {
+    return vi.fn();
+  }
+
+  function pressEnter(el: HTMLElement): { defaultPrevented: boolean } {
+    const evt = new KeyboardEvent("keydown", { key: "Enter", bubbles: true, cancelable: true });
+    el.dispatchEvent(evt);
+    return { defaultPrevented: evt.defaultPrevented };
+  }
+
+  const box = (form: HTMLFormElement, path: string) =>
+    form.querySelector<HTMLButtonElement>(`.project-box[data-cwd="${path}"]`)!;
+
+  it("toggles the worktree checkbox on Enter instead of submitting (TUI parity)", async () => {
+    const form = await mount([MAESTRO]);
+    box(form, MAESTRO.path).click();
+    await drain();
+    const toggle = form.querySelector<HTMLInputElement>("input[name=worktree_enabled]")!;
+    expect(toggle.checked).toBe(true);
+    const spy = submitSpy();
+    form.addEventListener("submit", spy);
+
+    pressEnter(toggle);
+    expect(toggle.checked).toBe(false);
+    expect(spy).not.toHaveBeenCalled();
+
+    pressEnter(toggle);
+    expect(toggle.checked).toBe(true);
+    expect(spy).not.toHaveBeenCalled();
+  });
+
+  describe("submits immediately from ordinary fields", () => {
+    it("name field", async () => {
+      const form = await mount([MAESTRO]);
+      box(form, MAESTRO.path).click();
+      await drain();
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      pressEnter(form.querySelector<HTMLInputElement>("input[name=name]")!);
+
+      expect(spy).toHaveBeenCalledTimes(1);
+    });
+
+    it("worktree branch field", async () => {
+      const form = await mount([MAESTRO]);
+      box(form, MAESTRO.path).click();
+      await drain();
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      pressEnter(form.querySelector<HTMLInputElement>("input[name=worktree_branch]")!);
+
+      expect(spy).toHaveBeenCalledTimes(1);
+    });
+
+    it("custom command field", async () => {
+      const form = await mount([MAESTRO]);
+      box(form, MAESTRO.path).click();
+      await drain();
+      form.querySelector<HTMLButtonElement>('.cmd-tiles .tile[data-id="custom"]')!.click();
+      const raw = form.querySelector<HTMLInputElement>(".cmd-raw")!;
+      raw.value = "bash -l";
+      raw.dispatchEvent(new Event("input"));
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      pressEnter(raw);
+
+      expect(spy).toHaveBeenCalledTimes(1);
+    });
+
+    it("raw cwd field once the autocomplete dropdown is closed", async () => {
+      const form = await mount([MAESTRO]);
+      form.querySelector<HTMLButtonElement>(".project-other")!.click();
+      const raw = form.querySelector<HTMLInputElement>("input[name=cwd_raw]")!;
+      raw.value = "/opt/xyz-nothing-here";
+      raw.dispatchEvent(new Event("input"));
+      await vi.advanceTimersByTimeAsync(300);
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      pressEnter(raw);
+
+      expect(spy).toHaveBeenCalledTimes(1);
+    });
+
+    it("does not submit while the raw cwd autocomplete has a highlighted suggestion", async () => {
+      const form = await mount([MAESTRO]);
+      form.querySelector<HTMLButtonElement>(".project-other")!.click();
+      const raw = form.querySelector<HTMLInputElement>("input[name=cwd_raw]")!;
+      raw.focus();
+      raw.value = "/opt/";
+      raw.dispatchEvent(new Event("input", { bubbles: true }));
+      await vi.advanceTimersByTimeAsync(150);
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      const { defaultPrevented } = pressEnter(raw);
+
+      expect(defaultPrevented).toBe(true);
+      expect(spy).not.toHaveBeenCalled();
+      expect(raw.value).toBe("/opt/nomatch-zzz/");
+    });
+  });
+
+  describe("two-step picker: first Enter chooses, second submits", () => {
+    it("project box", async () => {
+      const form = await mount([MAESTRO]);
+      const b = box(form, MAESTRO.path);
+      b.focus();
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      const first = pressEnter(b);
+      expect(first.defaultPrevented).toBe(true);
+      expect(b.classList.contains("is-active")).toBe(true);
+      expect(spy).not.toHaveBeenCalled();
+
+      pressEnter(b);
+      expect(spy).toHaveBeenCalledTimes(1);
+    });
+
+    it("worktree choice", async () => {
+      const form = await mount([MAESTRO, WT_A]);
+      box(form, MAESTRO.path).click();
+      await drain();
+      const choice = form.querySelector<HTMLButtonElement>(`.wt-choice[data-cwd="${WT_A.path}"]`)!;
+      expect(choice.classList.contains("is-active")).toBe(false); // "+ new" is the default
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      pressEnter(choice);
+      expect(choice.classList.contains("is-active")).toBe(true);
+      expect(spy).not.toHaveBeenCalled();
+
+      pressEnter(choice);
+      expect(spy).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  describe("project filter", () => {
+    it("submits with the highlighted (first matching) project, not the filter text", async () => {
+      const form = await mount([MAESTRO, OTHER]);
+      const filter = form.querySelector<HTMLInputElement>(".project-filter")!;
+      filter.value = "rev";
+      filter.dispatchEvent(new Event("input"));
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      pressEnter(filter);
+
+      expect(spy).toHaveBeenCalledTimes(1);
+      expect(box(form, OTHER.path).classList.contains("is-active")).toBe(true);
+    });
+
+    it("does not clobber an already-chosen worktree when the filter still matches it", async () => {
+      const form = await mount([MAESTRO, WT_A]);
+      box(form, MAESTRO.path).click();
+      await drain();
+      form.querySelector<HTMLButtonElement>(`.wt-choice[data-cwd="${WT_A.path}"]`)!.click();
+      await drain();
+
+      const filter = form.querySelector<HTMLInputElement>(".project-filter")!;
+      filter.value = "maestro";
+      filter.dispatchEvent(new Event("input"));
+      const spy = submitSpy();
+      form.addEventListener("submit", spy);
+
+      pressEnter(filter);
+
+      expect(spy).toHaveBeenCalledTimes(1);
+      expect(
+        form.querySelector<HTMLButtonElement>(`.wt-choice[data-cwd="${WT_A.path}"]`)!.classList.contains(
+          "is-active",
+        ),
+      ).toBe(true);
+    });
+  });
+});

web/src/tree.test.ts

@@ -95,3 +95,59 @@ describe("mergeLinear", () => {
     expect(merged.path).toBe("a/b");
   });
 });
+
+describe("worktree sessions group under their repository (#99)", () => {
+  /** A session the daemon spawned into a worktree of `repo`. */
+  function worktreeSession(id: string, repo: string, wt: string): Session {
+    return { ...session(id, wt), worktree: { path: wt, base_repo: repo } } as Session;
+  }
+
+  /** Top-level folder names, after linear chains are collapsed. */
+  function topFolders(root: TreeFolder): string[] {
+    return root.children.filter((c) => c.kind === "folder").map((c) => (c as TreeFolder).name);
+  }
+
+  it("nests under the repo, not the worktree directory", () => {
+    const root = buildTree(
+      [
+        worktreeSession(
+          "a",
+          "/home/n/tea/agent-skills",
+          "/home/n/tea/agent-skills/worktrees/largo-clarinet",
+        ),
+      ],
+      "/home/n",
+      "",
+    ) as TreeFolder;
+
+    expect(topFolders(root)).toEqual(["~/tea/agent-skills"]);
+    const repo = root.children[0] as TreeFolder;
+    expect(repo.children).toHaveLength(1);
+    expect(repo.children[0].kind).toBe("leaf");
+  });
+
+  it("puts a repo's plain and worktree sessions side by side", () => {
+    const root = buildTree(
+      [
+        session("plain", "/home/n/tea/agent-skills"),
+        worktreeSession(
+          "wt",
+          "/home/n/tea/agent-skills",
+          "/home/n/tea/agent-skills/worktrees/largo-clarinet",
+        ),
+      ],
+      "/home/n",
+      "",
+    ) as TreeFolder;
+
+    expect(topFolders(root)).toEqual(["~/tea/agent-skills"]);
+    const repo = root.children[0] as TreeFolder;
+    expect(repo.children).toHaveLength(2);
+    expect(repo.children.every((c) => c.kind === "leaf")).toBe(true);
+  });
+
+  it("leaves a session without a worktree where it is", () => {
+    const root = buildTree([session("a", "/home/n/tea/arr")], "/home/n", "") as TreeFolder;
+    expect(topFolders(root)).toEqual(["~/tea/arr"]);
+  });
+});

web/src/tree.ts

@@ -2,7 +2,7 @@
 // so it can be tested directly.
 
 import type { Session } from "./types.js";
-import { abbreviateCwd, sessionCwd, sessionName } from "./types.js";
+import { abbreviateCwd, sessionName, sessionTreePath } from "./types.js";
 
 export interface TreeFolder {
   kind: "folder";
@@ -30,7 +30,9 @@ export function buildTree(sessions: Session[], home: string | undefined, filter:
   const lc = filter.trim().toLowerCase();
 
   for (const s of sessions) {
-    const cwd = sessionCwd(s);
+    // Grouped by repository, so a worktree session lands under its repo
+    // rather than in a folder of its own (#99).
+    const cwd = sessionTreePath(s);
     const dir = cwd ? abbreviateCwd(cwd, home) : "";
     if (lc) {
       const haystack = `${sessionName(s)} ${dir}`.toLowerCase();

web/src/types.ts

@@ -9,8 +9,9 @@ export type IsoTimestamp = string;
 export type SessionStatus = "Running" | "Dead";
 
 /** Daemon-inferred activity dimension, orthogonal to `SessionStatus` (NAP-340).
- * Absent on payloads from daemons that predate the field. */
-export type ActivityState = "Active" | "Idle" | "AwaitingInput";
+ * Absent on payloads from daemons that predate the field. `Error` is only set
+ * when an agent reports failure (#105); the daemon never infers it. */
+export type ActivityState = "Active" | "Idle" | "AwaitingInput" | "Error";
 
 export interface Session {
   id: Uuid;
@@ -27,6 +28,11 @@ export interface Session {
   activity?: ActivityState;
   /** Wall-clock of the most recent observed PTY output (NAP-340). */
   last_activity_at?: IsoTimestamp;
+  /** Wall-clock of when the session entered its current `activity` state
+   * (#102) — distinct from `last_activity_at`, which only tracks PTY output.
+   * Defaults to the Unix epoch on payloads from daemons that predate the
+   * field. */
+  activity_since?: IsoTimestamp;
   /** The pane's *current* working directory, as the daemon's activity watcher
    * observed it (`#{pane_current_path}`) — distinct from `cwd` (the spawn dir).
    * Drives the directory-based session tree. Absent until first observed. */
@@ -36,6 +42,16 @@ export interface Session {
    * without a worktree; all counts default to 0 on the wire for older
    * daemons. */
   blocked_work?: InTheWay | null;
+  /** The worktree the daemon created for this session, absent when it did not
+   * create one. `base_repo` is the repository's main checkout, which is what
+   * the session tree groups by (#99). */
+  worktree?: SessionWorktree | null;
+}
+
+/** A session's daemon-created worktree (`SessionWorktree` on the wire). */
+export interface SessionWorktree {
+  path: string;
+  base_repo: string;
 }
 
 /** One directory's immediate subdirectories (NAP-329). */
@@ -231,12 +247,23 @@ export function sessionName(s: Session): string {
 }
 
 /** The directory a session lives in: its live `current_cwd` if the daemon has
- * observed one, else the spawn `cwd`. Drives the directory-based session tree. */
+ * observed one, else the spawn `cwd`. */
 export function sessionCwd(s: Session): string | undefined {
   if (typeof s.current_cwd === "string" && s.current_cwd) return s.current_cwd;
   return s.cwd || undefined;
 }
 
+/** Where a session sits in the directory tree. A worktree session belongs to
+ * its repository, not to the worktree (#99): otherwise `~/tea/agent-skills`
+ * grows a `~/tea/agent-skills/worktrees/largo-clarinet` folder holding one
+ * session of the same name, and the repository stops being where you look for
+ * the work. `base_repo` is the main checkout — the daemon resolves it. */
+export function sessionTreePath(s: Session): string | undefined {
+  const repo = s.worktree?.base_repo;
+  if (typeof repo === "string" && repo) return repo;
+  return sessionCwd(s);
+}
+
 /** Collapse a daemon's home dir to `~`. `home` comes from `DaemonInfo.home_dir`;
  * absent/empty leaves the path untouched. Mirrors the CLI's `abbreviate_dir`. */
 export function abbreviateCwd(cwd: string, home?: string): string {