Sidebar collapses multiple sessions sharing `(project_path, branch)` into one row

[Seluj78]

Disclaimer: this issue was drafted by Claude after I had it investigate the bug — I reviewed and agree with the contents.

Repro

1. aoe add /some/repo --cmd claude --cockpit
2. aoe add /some/repo --cmd claude --cockpit
   (or any combination of two sessions with the same project_path and no --worktree branch; cockpit_mode is incidental, reproduces with tmux sessions too)
3. aoe serve
4. Open the dashboard and refresh.

Expected

Both sessions appear in the sidebar.

Actual

Only the first session in the API response appears. The second session is in GET /api/sessions (visible in the network tab) but never rendered in the sidebar. Refreshing does not help.

Root cause

The sidebar groups sessions by (project_path, branch) into "workspaces" and then renders one SessionRow per workspace using workspace.sessions[0]. Sibling sessions in the same workspace are dropped from the visible UI.

Code references

web/src/hooks/useWorkspaces.ts:18

const key = `${repoPath}::${session.branch ?? "__default__"}`;

All sessions sharing (main_repo_path or project_path, branch) collapse into the same workspace entry.

web/src/components/WorkspaceSidebar.tsx:134-138

const label = workspace.branch ?? workspace.sessions[0]?.title ?? "default";
const runningSession = workspace.sessions.find((s) => isSessionActive(s));
const firstSession = workspace.sessions[0];
const sessionId = firstSession?.id;
const navigationSessionId = runningSession?.id ?? firstSession?.id ?? null;

The row binds to firstSession (or runningSession) only. There is no expansion / sub-list rendering workspace.sessions[1..].

web/src/components/WorkspaceSidebar.tsx:638-648

{showExpanded &&
  group.workspaces.map((ws) => (
    <SessionRow ... workspace={ws} ... />
  ))}

The group expansion iterates workspaces, not sessions, so the second session is never reached.

Concrete repro on a fresh checkout

Ethiopians  project_path=/private/tmp/agent-of-empires
Italians    project_path=/Users/seluj78/Projects/Personnal/agent-of-empires
Celts       project_path=/Users/seluj78/Projects/Personnal/agent-of-empires
Magyars     (separate workspace)

• GET /api/sessions returns all 4
• Sidebar shows 2 rows (Magyars and Italians); Ethiopians and Celts are invisible

Workarounds

• Pass --worktree <branch> on add so the session has a distinct (project_path, branch) key
• Delete the colliding session
• Use distinct project_paths

Possible fixes (in increasing scope)

1. Append a session-count badge to SessionRow when workspace.sessions.length > 1, plus an expander that lists the sibling sessions (use their title, since branch is shared/null).
2. Stop collapsing sessions into workspaces when branch is null; render one row per session for the "no worktree" case.
3. Group by (project_path, branch, title) so identical branches still collide but distinct titles do not.

Environment

• Branch: fix/cockpit-reconcile-spawn (against njbrake/native, PR fix(cockpit): auto-spawn ACP workers for sessions added while serve runs #953)
• Predates the cockpit feature; reproduces with tmux-only sessions too
• macOS, Darwin 24.6.0

Notes

Originally surfaced while testing PR #953 (cockpit reconciler). The cockpit reconciler is unrelated; the same bug reproduces with --no-cockpit sessions sharing a project_path.