feat: workspaces shell + cwd-lsp rename + mcp/settings/system-prompt features + app wiring

- workspaces: URL-driven conversation grouping (home listing at /, routing,
  store, http adapter, WorkspaceCard) wired into the App.svelte shell
- rename features/workspace -> features/cwd-lsp (the cwd/lsp status feature)
- new features: mcp (status view), settings (chat-limit field), system-prompt
  (prompt builder), all rendered via the generic surface host
- chat: store + ChatView updates
- tabs: tabs-store updates
- app wiring: ErrorModal (full-screen error surface), app/App.svelte + store.svelte

This commit makes HEAD typecheck clean for the first time: the prior HEAD
(c95cc77) imported features/settings from app/App.svelte but never committed
the feature, so only the full working tree was green.

1 files changed, 134 insertions, 0 deletions

diff --git a/src/features/workspaces/adapter/http.ts b/src/features/workspaces/adapter/http.ts
new file mode 100644
index 0000000..97fc2e2
--- /dev/null
+++ b/src/features/workspaces/adapter/http.ts
@@ -0,0 +1,134 @@
+import type {
+	DeleteWorkspaceResponse,
+	EnsureWorkspaceRequest,
+	SetWorkspaceDefaultCwdRequest,
+	SetWorkspaceTitleRequest,
+	Workspace,
+	WorkspaceEntry,
+	WorkspaceListResponse,
+	WorkspaceResponse,
+} from "@dispatch/transport-contract";
+
+/**
+ * Workspace HTTP effects — the injected edge that talks to the backend's
+ * workspace endpoints. Mirrors the store's fetch pattern: `httpBase` + an
+ * injected `fetchImpl` (so it is testable without the network). Returns typed
+ * `WorkspaceResult<T>` (`{ok,value}` | `{ok:false,error}`) for mutating ops so a
+ * caller can surface the backend's `{ error }` reason; reads return data or a
+ * safe empty/null on failure (non-fatal — the UI falls back gracefully).
+ *
+ * Endpoints ([email protected]):
+ * - `GET /workspaces` → list
+ * - `PUT /workspaces/:id` (create-on-miss, idempotent) → ensure
+ * - `GET /workspaces/:id` (404 → null) → get
+ * - `PUT /workspaces/:id/title` → rename
+ * - `PUT /workspaces/:id/default-cwd` → set/clear default cwd
+ * - `DELETE /workspaces/:id` (409 for "default") → delete
+ */
+export type WorkspaceResult<T> =
+	| { readonly ok: true; readonly value: T }
+	| { readonly ok: false; readonly error: string };
+
+export interface WorkspaceHttp {
+	list(): Promise<readonly WorkspaceEntry[]>;
+	ensure(id: string, body?: EnsureWorkspaceRequest): Promise<WorkspaceResult<Workspace>>;
+	get(id: string): Promise<Workspace | null>;
+	setTitle(id: string, title: string): Promise<WorkspaceResult<Workspace>>;
+	setDefaultCwd(id: string, defaultCwd: string | null): Promise<WorkspaceResult<Workspace>>;
+	delete(id: string): Promise<WorkspaceResult<{ closedCount: number }>>;
+}
+
+async function errText(res: Response): Promise<string> {
+	try {
+		const body = (await res.json()) as { error?: string };
+		return body.error ?? `HTTP ${res.status}`;
+	} catch {
+		return `HTTP ${res.status}`;
+	}
+}
+
+export function createWorkspaceHttp(httpBase: string, fetchImpl: typeof fetch): WorkspaceHttp {
+	return {
+		async list(): Promise<readonly WorkspaceEntry[]> {
+			try {
+				const res = await fetchImpl(`${httpBase}/workspaces`);
+				if (!res.ok) return [];
+				const data = (await res.json()) as WorkspaceListResponse;
+				return data.workspaces;
+			} catch {
+				return [];
+			}
+		},
+
+		async ensure(id, body): Promise<WorkspaceResult<Workspace>> {
+			try {
+				const res = await fetchImpl(`${httpBase}/workspaces/${encodeURIComponent(id)}`, {
+					method: "PUT",
+					headers: { "Content-Type": "application/json" },
+					body: JSON.stringify(body ?? {}),
+				});
+				if (!res.ok) return { ok: false, error: await errText(res) };
+				return { ok: true, value: (await res.json()) as WorkspaceResponse };
+			} catch (err) {
+				return {
+					ok: false,
+					error: err instanceof Error ? err.message : "Workspace request failed",
+				};
+			}
+		},
+
+		async get(id): Promise<Workspace | null> {
+			try {
+				const res = await fetchImpl(`${httpBase}/workspaces/${encodeURIComponent(id)}`);
+				if (res.status === 404 || !res.ok) return null;
+				return (await res.json()) as WorkspaceResponse;
+			} catch {
+				return null;
+			}
+		},
+
+		async setTitle(id, title): Promise<WorkspaceResult<Workspace>> {
+			try {
+				const res = await fetchImpl(`${httpBase}/workspaces/${encodeURIComponent(id)}/title`, {
+					method: "PUT",
+					headers: { "Content-Type": "application/json" },
+					body: JSON.stringify({ title } satisfies SetWorkspaceTitleRequest),
+				});
+				if (!res.ok) return { ok: false, error: await errText(res) };
+				return { ok: true, value: (await res.json()) as WorkspaceResponse };
+			} catch (err) {
+				return { ok: false, error: err instanceof Error ? err.message : "Rename failed" };
+			}
+		},
+
+		async setDefaultCwd(id, defaultCwd): Promise<WorkspaceResult<Workspace>> {
+			try {
+				const res = await fetchImpl(
+					`${httpBase}/workspaces/${encodeURIComponent(id)}/default-cwd`,
+					{
+						method: "PUT",
+						headers: { "Content-Type": "application/json" },
+						body: JSON.stringify({ defaultCwd } satisfies SetWorkspaceDefaultCwdRequest),
+					},
+				);
+				if (!res.ok) return { ok: false, error: await errText(res) };
+				return { ok: true, value: (await res.json()) as WorkspaceResponse };
+			} catch (err) {
+				return { ok: false, error: err instanceof Error ? err.message : "Set default cwd failed" };
+			}
+		},
+
+		async delete(id): Promise<WorkspaceResult<{ closedCount: number }>> {
+			try {
+				const res = await fetchImpl(`${httpBase}/workspaces/${encodeURIComponent(id)}`, {
+					method: "DELETE",
+				});
+				if (!res.ok) return { ok: false, error: await errText(res) };
+				const data = (await res.json()) as DeleteWorkspaceResponse;
+				return { ok: true, value: { closedCount: data.closedCount } };
+			} catch (err) {
+				return { ok: false, error: err instanceof Error ? err.message : "Delete failed" };
+			}
+		},
+	};
+}