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.

3 files changed, 68 insertions, 6 deletions

diff --git a/src/features/chat/index.ts b/src/features/chat/index.ts
index 1596c53..c120916 100644
--- a/src/features/chat/index.ts
+++ b/src/features/chat/index.ts
@@ -1,5 +1,10 @@
-export type { RenderedChunk, RenderGroup, ToolBatchEntry } from "../../core/chunks";
-export { groupRenderedChunks } from "../../core/chunks";
+export type {
+	ProviderRetryView,
+	RenderedChunk,
+	RenderGroup,
+	ToolBatchEntry,
+} from "../../core/chunks";
+export { groupRenderedChunks, viewProviderRetry } from "../../core/chunks";
 export type { TurnMetricsEntry } from "../../core/metrics";
 export type { ChatTransport, HistorySync, HistoryWindow, MetricsSync } from "./ports";
 export type {
diff --git a/src/features/chat/store.svelte.ts b/src/features/chat/store.svelte.ts
index 9beabfc..a31fe55 100644
--- a/src/features/chat/store.svelte.ts
+++ b/src/features/chat/store.svelte.ts
@@ -4,7 +4,7 @@ import type {
 	ChatQueueMessage,
 	ChatSendMessage,
 } from "@dispatch/transport-contract";
-import type { ChatMessage, StoredChunk } from "@dispatch/wire";
+import type { ChatMessage, StoredChunk, TurnProviderRetryEvent } from "@dispatch/wire";
 import type { RenderedChunk, TranscriptState } from "../../core/chunks";
 import {
 	appendUserMessage,
@@ -19,6 +19,7 @@ import {
 	selectGenerating,
 	selectHasEarlier,
 	selectMessages,
+	selectProviderRetry,
 	trimTranscript,
 	unloadCount,
 	windowTranscript,
@@ -42,6 +43,12 @@ export interface ChatStoreDependencies {
 	readonly metricsSync: MetricsSync;
 	readonly cache: ConversationCache;
 	/**
+	 * The workspace this conversation belongs to (its URL slug). Sent on
+	 * `chat.send`/`chat.queue` so the backend stamps the conversation's workspace
+	 * at creation (default "default"). Absent → omitted (legacy behavior).
+	 */
+	readonly workspaceId?: string;
+	/**
 	 * The chat limit: max loaded chunks before the oldest quarter is unloaded
 	 * (see `core/chunks/trim.ts`). Normalized via `normalizeChatLimit`; absent →
 	 * `DEFAULT_CHAT_LIMIT`.
@@ -54,6 +61,12 @@ export interface ChatStoreDependencies {
 	 * to the bottom (the next fold retries). Absent → always allowed.
 	 */
 	readonly canUnload?: () => boolean;
+	/**
+	 * Called when a swallowed error should be surfaced to the user (e.g. a
+	 * metrics sync failure). Wired by the composition root to the app store's
+	 * `reportError` → full-screen error modal. Absent → errors are logged only.
+	 */
+	readonly onError?: (context: string, err: unknown) => void;
 }
 
 export interface ChatStore {
@@ -73,6 +86,13 @@ export interface ChatStore {
 	 * turn was replayed. Drives the composer's "generating…" indicator.
 	 */
 	readonly generating: boolean;
+	/**
+	 * The latest `provider-retry` event for the current turn, or `null` when no
+	 * retry is pending. Drives the transient yellow "retrying…" warning banner —
+	 * never persisted (never sent to the model or replayed on reload). Coalesces
+	 * to the newest attempt + delay; cleared when content resumes or the turn ends.
+	 */
+	readonly providerRetry: TurnProviderRetryEvent | null;
 	readonly pendingSync: boolean;
 	readonly error: string | null;
 	readonly model: string | undefined;
@@ -183,9 +203,11 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
 		try {
 			const res = await deps.metricsSync(deps.conversationId);
 			metrics = applyDurableMetrics(metrics, res.turns);
-		} catch {
+		} catch (err) {
 			// Metrics fetch failure must not block history sync or throw;
-			// live-folded metrics remain intact.
+			// live-folded metrics remain intact. Surface via onError (modal).
+			console.error("[syncMetrics] failed:", err);
+			deps.onError?.("Failed to sync conversation metrics", err);
 		}
 	}
 
@@ -251,6 +273,9 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
 		get generating(): boolean {
 			return selectGenerating(transcript);
 		},
+		get providerRetry(): TurnProviderRetryEvent | null {
+			return selectProviderRetry(transcript);
+		},
 		get pendingSync(): boolean {
 			return _pendingSync;
 		},
@@ -295,6 +320,7 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
 				conversationId: deps.conversationId,
 				message: text,
 				...(_model !== undefined ? { model: _model } : {}),
+				...(deps.workspaceId !== undefined ? { workspaceId: deps.workspaceId } : {}),
 			};
 			deps.transport.send(msg);
 		},
@@ -306,6 +332,7 @@ export function createChatStore(deps: ChatStoreDependencies): ChatStore {
 				type: "chat.queue",
 				conversationId: deps.conversationId,
 				text: trimmed,
+				...(deps.workspaceId !== undefined ? { workspaceId: deps.workspaceId } : {}),
 			};
 			deps.transport.send(msg);
 		},
diff --git a/src/features/chat/ui/ChatView.svelte b/src/features/chat/ui/ChatView.svelte
index 2b55eb3..f2899c7 100644
--- a/src/features/chat/ui/ChatView.svelte
+++ b/src/features/chat/ui/ChatView.svelte
@@ -1,5 +1,6 @@
 <script lang="ts">
-	import { groupRenderedChunks, type RenderedChunk } from "../index";
+	import type { TurnProviderRetryEvent } from "@dispatch/wire";
+	import { groupRenderedChunks, type RenderedChunk, viewProviderRetry } from "../index";
 	import {
 		interleaveTurnMetrics,
 		viewCacheRate,
@@ -22,6 +23,7 @@
 		hasEarlier = false,
 		onShowEarlier,
 		thinkingKeyBase = 0,
+		providerRetry = null,
 	}: {
 		chunks: readonly RenderedChunk[];
 		turnMetrics?: readonly TurnMetricsEntry[];
@@ -35,6 +37,13 @@
 		 * swap collapse state) when a trim removes older thinking blocks.
 		 */
 		thinkingKeyBase?: number;
+		/**
+		 * The latest `provider-retry` event for the current turn, or `null` when
+		 * no retry is pending → renders the transient yellow "retrying…" banner.
+		 * Never persisted (never part of the message history); coalesces to the
+		 * newest attempt + delay, and is cleared when content resumes / turn ends.
+		 */
+		providerRetry?: TurnProviderRetryEvent | null;
 	} = $props();
 
 	// True while a show-earlier page-in is awaited (disables the button).
@@ -261,4 +270,25 @@
 			</div>
 		{/if}
 	{/each}
+	{#if providerRetry}
+		{@const rv = viewProviderRetry(providerRetry)}
+		<!-- Transient yellow warning: a provider error is being retried with backoff.
+		     NOT a message chunk (never persisted/replayed) — a live UI notification only,
+		     shown where the reply would appear. Coalesces to the newest attempt + delay,
+		     and is cleared (foldEvent) when content resumes or the turn ends. -->
+		<div class="chat chat-start [&>.chat-bubble]:max-w-5xl">
+			<div class="chat-bubble w-full bg-transparent">
+				<div class="alert alert-warning flex-wrap items-start gap-2 py-2 text-sm" role="status">
+					<div class="flex flex-wrap items-center gap-2 font-medium">
+						<span aria-hidden="true">⚠</span>
+						<span>{rv.attemptLabel} — retrying in {rv.delayLabel}…</span>
+						{#if rv.code}
+							<span class="badge badge-warning badge-sm font-mono">{rv.code}</span>
+						{/if}
+					</div>
+					<div class="w-full font-mono text-xs opacity-70">{rv.message}</div>
+				</div>
+			</div>
+		</div>
+	{/if}
 </div>