fix: add top-level GET /workspaces endpoint and derive project/repo from workspace data

- Add all_workspaces_router with GET /workspaces/ (no project/repo required)
- Include project_id in workspace responses
- Frontend: useWorkspaces() calls listAllWorkspaces when no args
- Frontend: WorkspacesPage uses top-level list, derives project/repo from workspace for mutations
- Fixes 422 from invalid UUID path params

apps/api/src/api/workspaces.py

@@ -17,6 +17,54 @@ from src.services.workspace_manager import WorkspaceHasInstancesError, Workspace
 logger = logging.getLogger(__name__)
 
 router = APIRouter(prefix="/projects/{project_id}/repositories/{repo_id}/workspaces")
+all_workspaces_router = APIRouter(prefix="/workspaces")
+
+
+@all_workspaces_router.get("/")
+async def list_all_workspaces(
+    user_id: uuid.UUID = Depends(get_current_user_id),
+    session: AsyncSession = Depends(get_db_session),
+) -> list[dict]:
+    """List all workspaces for the current user across all repos."""
+    instance_count = (
+        select(func.count(ToolInstance.id))
+        .where(ToolInstance.workspace_id == Workspace.id)
+        .correlate(Workspace)
+        .scalar_subquery()
+    )
+
+    result = await session.execute(
+        select(
+            Workspace,
+            GitRepository.name.label("repo_name"),
+            GitRepository.project_id,
+            instance_count.label("instance_count"),
+        )
+        .join(GitRepository, Workspace.repo_id == GitRepository.id)
+        .where(Workspace.user_id == user_id)
+        .order_by(Workspace.created_at.desc())
+    )
+    rows = result.all()
+
+    return [
+        {
+            "id": str(ws.id),
+            "name": ws.name,
+            "repo_id": str(ws.repo_id),
+            "repo_name": repo_name or "",
+            "project_id": str(project_id) if project_id else "",
+            "project_name": "",  # Could join with Project if needed
+            "user_id": str(ws.user_id),
+            "branch": ws.branch,
+            "path": ws.path,
+            "status": ws.status,
+            "last_sync_at": ws.last_sync_at.isoformat() if ws.last_sync_at else None,
+            "created_at": ws.created_at.isoformat() if ws.created_at else None,
+            "updated_at": ws.updated_at.isoformat() if ws.updated_at else None,
+            "instance_count": count or 0,
+        }
+        for ws, repo_name, project_id, count in rows
+    ]
 
 
 @router.get("/")
@@ -54,6 +102,7 @@ async def list_workspaces(
             "name": ws.name,
             "repo_id": str(ws.repo_id),
             "repo_name": repo.name,
+            "project_id": str(repo.project_id) if repo.project_id else "",
             "project_name": repo.project.name if repo.project else "",
             "user_id": str(ws.user_id),
             "branch": ws.branch,