feat: complete working-copies workspace-first cleanup

- Remove clone_mode/branch/new_branch from frontend create session flow.
- Add workspace picker to CreateSessionForm; auto-create default workspace when repo selected.
- Fix tool-starter.tsx and use-start-tool.ts createInstance signatures after API change.
- Remove clone mode badge from SessionCard.
- Delete stale backend unit tests referencing removed clone_mode schema fields.
- Update OpenSpec working-copies tasks and mark change completed.
- Regenerate project maps.

Quality gates: npm run typecheck, npm run lint, npm test -- --run (82 passed),
python3 -m py_compile on changed backend files.

apps/web/src/components/features/session/create-session-form.tsx

@@ -13,6 +13,8 @@ import {
 	listConfigProfiles,
 	type ConfigProfile,
 } from "../../../api/config-profiles";
+import { listWorkspaces, createWorkspace } from "../../../api/workspaces";
+import type { Workspace } from "../../../types/workspace";
 
 interface CreateSessionFormProps {
 	projects: Project[];
@@ -54,6 +56,10 @@ export const CreateSessionForm = ({
 	const [selectedConfigProfile, setSelectedConfigProfile] = useState("");
 	const [selectedSshKeyIds, setSelectedSshKeyIds] = useState<string[]>([]);
 
+	const [workspaces, setWorkspaces] = useState<Workspace[]>([]);
+	const [selectedWorkspaceId, setSelectedWorkspaceId] = useState("");
+	const [isLoadingWorkspaces, setIsLoadingWorkspaces] = useState(false);
+
 	const [isSubmitting, setIsSubmitting] = useState(false);
 	const [error, setError] = useState<string | null>(null);
 
@@ -94,6 +100,50 @@ export const CreateSessionForm = ({
 		void loadProfiles();
 	}, [selectedToolType, selectedProject, fixedProjectId]);
 
+	// Load workspaces when repository is selected
+	useEffect(() => {
+		const projectId = fixedProjectId || selectedProject;
+		const repoId = fixedRepoId || selectedRepo;
+		if (!projectId || !repoId) {
+			setWorkspaces([]);
+			setSelectedWorkspaceId("");
+			return;
+		}
+		const loadWorkspaces = async () => {
+			setIsLoadingWorkspaces(true);
+			try {
+				const data = await listWorkspaces(projectId, repoId);
+				setWorkspaces(data);
+				if (data.length > 0) {
+					setSelectedWorkspaceId(data[0].id);
+				} else {
+					// Auto-create a default workspace so the user can start a tool
+					const workspace = await createWorkspace(projectId, repoId, {
+						name: "default",
+						branch: "main",
+					});
+					setWorkspaces([workspace]);
+					setSelectedWorkspaceId(workspace.id);
+				}
+			} catch (err) {
+				setError(
+					err instanceof Error ? err.message : "Failed to load workspaces",
+				);
+				setWorkspaces([]);
+				setSelectedWorkspaceId("");
+			} finally {
+				setIsLoadingWorkspaces(false);
+			}
+		};
+		void loadWorkspaces();
+	}, [
+		fixedProjectId,
+		selectedProject,
+		fixedRepoId,
+		selectedRepo,
+		repositories,
+	]);
+
 	// Filter repositories by selected project
 	const availableRepos = selectedProject
 		? repositories.filter((r) => r.project_id === selectedProject)
@@ -106,6 +156,8 @@ export const CreateSessionForm = ({
 		setDisplayName("");
 		setSelectedSshKeyIds([]);
 		setSelectedConfigProfile("");
+		setWorkspaces([]);
+		setSelectedWorkspaceId("");
 	};
 
 	const handleSubmit = async (event: React.FormEvent) => {
@@ -123,12 +175,19 @@ export const CreateSessionForm = ({
 		setIsSubmitting(true);
 
 		try {
+			const workspaceId = selectedWorkspaceId || undefined;
+			if (!workspaceId) {
+				setError("No workspace available for the selected repository");
+				setIsSubmitting(false);
+				return;
+			}
+
 			const instance = await createInstance(
 				projectId,
 				repoId,
 				selectedToolType,
 				displayName || undefined,
-				undefined,
+				workspaceId,
 				selectedConfigProfile || undefined,
 				selectedSshKeyIds.length > 0 ? selectedSshKeyIds : undefined,
 			);
@@ -214,6 +273,7 @@ export const CreateSessionForm = ({
 								onChange={(e) => {
 									setSelectedRepo(e.target.value);
 									setSelectedToolType("");
+									setSelectedWorkspaceId("");
 								}}
 								disabled={!hasProject || isSubmitting}
 							>
@@ -228,6 +288,30 @@ export const CreateSessionForm = ({
 					</div>
 				)}
 
+				{/* Workspace */}
+				{hasRepo && (
+					<div className="form-field">
+						<label>Workspace</label>
+						{isLoadingWorkspaces ? (
+							<span className="muted">Loading workspaces...</span>
+						) : workspaces.length === 0 ? (
+							<span className="muted">No workspace available</span>
+						) : (
+							<select
+								value={selectedWorkspaceId}
+								onChange={(e) => setSelectedWorkspaceId(e.target.value)}
+								disabled={!hasRepo || isSubmitting || isLoadingWorkspaces}
+							>
+								{workspaces.map((w) => (
+									<option key={w.id} value={w.id}>
+										{w.name} ({w.branch})
+									</option>
+								))}
+							</select>
+						)}
+					</div>
+				)}
+
 				{/* Tool Type */}
 				{hasRepo && (
 					<div className="form-field">