feat(ws): handle conversation.open broadcast — open/focus tab from CLI --open

Consume the conversation.open handoff ([email protected], [email protected]).
Re-pinned file: deps + re-mirrored .dispatch/*.reference.md.

- WS adapter (logic.ts + index.ts): parse + route the new top-level
  "conversation.open" WsServerMessage to an onConversationOpen handler
- app store: openConversation(id) opens (or focuses) a tab — creates a chat
  store, loads history, subscribes to live turns, creates+selects the tab
- conformance guard + WS adapter tests cover the new type
- backend also shipped conversation metadata endpoints (GET /conversations,
  GET /conversations/:id/last, GET/PUT /conversations/:id/title) — mirrored
  but not yet consumed by the FE

682 tests green.

7 files changed, 97 insertions, 1 deletions

diff --git a/src/adapters/ws/index.test.ts b/src/adapters/ws/index.test.ts
index 961f919..e13f123 100644
--- a/src/adapters/ws/index.test.ts
+++ b/src/adapters/ws/index.test.ts
@@ -269,6 +269,30 @@ describe("createSurfaceSocket", () => {
 		expect(onMessage).not.toHaveBeenCalled();
 	});
 
+	it("routes conversation.open to onConversationOpen", () => {
+		const ws = fakeSocket();
+		const onMessage = vi.fn();
+		const onChat = vi.fn();
+		const onConversationOpen = vi.fn();
+		createSurfaceSocket({
+			url: "ws://test",
+			onMessage,
+			onChat,
+			onConversationOpen,
+			socketFactory: () => ws,
+		});
+
+		ws.resolveOpen();
+		ws.invokeMessage(JSON.stringify({ type: "conversation.open", conversationId: "c1" }));
+		expect(onConversationOpen).toHaveBeenCalledOnce();
+		expect(onConversationOpen).toHaveBeenCalledWith({
+			type: "conversation.open",
+			conversationId: "c1",
+		});
+		expect(onMessage).not.toHaveBeenCalled();
+		expect(onChat).not.toHaveBeenCalled();
+	});
+
 	it("still routes surface catalog/surface to onMessage", () => {
 		const ws = fakeSocket();
 		const onMessage = vi.fn();
diff --git a/src/adapters/ws/index.ts b/src/adapters/ws/index.ts
index 54a501c..18ebdf7 100644
--- a/src/adapters/ws/index.ts
+++ b/src/adapters/ws/index.ts
@@ -1,6 +1,7 @@
 import type {
 	ChatDeltaMessage,
 	ChatErrorMessage,
+	ConversationOpenMessage,
 	WsClientMessage,
 } from "@dispatch/transport-contract";
 import type { SurfaceServerMessage } from "@dispatch/ui-contract";
@@ -18,6 +19,8 @@ export interface SurfaceSocketOptions {
 	url: string;
 	onMessage: (msg: SurfaceServerMessage) => void;
 	onChat?: (msg: ChatDeltaMessage | ChatErrorMessage) => void;
+	/** Broadcast when a conversation is "opened" (e.g. CLI `--open` flag). */
+	onConversationOpen?: (msg: ConversationOpenMessage) => void;
 	onReopen?: () => void;
 	socketFactory?: (url: string) => WebSocketLike;
 }
@@ -60,6 +63,8 @@ export function createSurfaceSocket(opts: SurfaceSocketOptions): SurfaceSocketHa
 			if (msg !== null) {
 				if (msg.type === "chat.delta" || msg.type === "chat.error") {
 					opts.onChat?.(msg as ChatDeltaMessage | ChatErrorMessage);
+				} else if (msg.type === "conversation.open") {
+					opts.onConversationOpen?.(msg as ConversationOpenMessage);
 				} else {
 					opts.onMessage(msg as SurfaceServerMessage);
 				}
diff --git a/src/adapters/ws/logic.test.ts b/src/adapters/ws/logic.test.ts
index 2784295..ca129c0 100644
--- a/src/adapters/ws/logic.test.ts
+++ b/src/adapters/ws/logic.test.ts
@@ -217,6 +217,22 @@ describe("parseServerMessage", () => {
 			),
 		).toBeNull();
 	});
+
+	it("parses a conversation.open message", () => {
+		const data = JSON.stringify({ type: "conversation.open", conversationId: "c1" });
+		const result = parseServerMessage(data);
+		expect(result).toEqual({ type: "conversation.open", conversationId: "c1" });
+	});
+
+	it("returns null for conversation.open with missing conversationId", () => {
+		expect(parseServerMessage(JSON.stringify({ type: "conversation.open" }))).toBeNull();
+	});
+
+	it("returns null for conversation.open with non-string conversationId", () => {
+		expect(
+			parseServerMessage(JSON.stringify({ type: "conversation.open", conversationId: 42 })),
+		).toBeNull();
+	});
 });
 
 describe("round-trip: parseServerMessage(serialize(...))", () => {
diff --git a/src/adapters/ws/logic.ts b/src/adapters/ws/logic.ts
index 17e3951..a9b70ff 100644
--- a/src/adapters/ws/logic.ts
+++ b/src/adapters/ws/logic.ts
@@ -1,6 +1,7 @@
 import type {
 	ChatDeltaMessage,
 	ChatErrorMessage,
+	ConversationOpenMessage,
 	WsClientMessage,
 	WsServerMessage,
 } from "@dispatch/transport-contract";
@@ -18,6 +19,7 @@ const VALID_SERVER_TYPES = new Set([
 	"error",
 	"chat.delta",
 	"chat.error",
+	"conversation.open",
 ]);
 
 /** Serialize a client message to a JSON string for the wire. */
@@ -107,6 +109,14 @@ export function parseServerMessage(data: string): WsServerMessage | null {
 					: { type: "chat.error", message: parsed.message };
 			return msg;
 		}
+		case "conversation.open": {
+			if (typeof parsed.conversationId !== "string") return null;
+			const msg: ConversationOpenMessage = {
+				type: "conversation.open",
+				conversationId: parsed.conversationId,
+			};
+			return msg;
+		}
 		default:
 			return null;
 	}
diff --git a/src/app/store.svelte.ts b/src/app/store.svelte.ts
index dc06ea1..5159353 100644
--- a/src/app/store.svelte.ts
+++ b/src/app/store.svelte.ts
@@ -3,6 +3,7 @@ import type {
 	ChatErrorMessage,
 	ConversationHistoryResponse,
 	ConversationMetricsResponse,
+	ConversationOpenMessage,
 	CwdResponse,
 	LspStatusResponse,
 	ModelsResponse,
@@ -432,10 +433,39 @@ export function createAppStore(opts?: CreateAppStoreOptions): AppStore {
 
 	let socket: ReturnType<typeof createSurfaceSocket> | null = null;
 
+	/**
+	 * Open (or focus) a conversation tab — used by the `conversation.open` WS
+	 * broadcast (CLI `--open` flag). If the conversation is already open, just
+	 * focus it; otherwise create a chat store, load its history, subscribe to its
+	 * live turns, and create+select the tab.
+	 */
+	function openConversation(conversationId: string): void {
+		const alreadyOpen = chatStores.has(conversationId);
+		if (!alreadyOpen) {
+			const store = createChatFor(conversationId, activeModel);
+			chatStores.set(conversationId, store);
+			void store.load();
+			subscribeChat(conversationId);
+			tabsStore.createTab({
+				conversationId,
+				model: activeModel,
+				title: "Conversation",
+			});
+		}
+		tabsStore.selectTab(conversationId);
+		refreshActiveChat();
+		syncSubscriptions();
+		void refreshCwd();
+		void refreshReasoningEffort();
+	}
+
 	const socketOpts: SurfaceSocketOptions = {
 		url: wsUrl,
 		onMessage: handleServerMessage,
 		onChat: handleChatMessage,
+		onConversationOpen(msg: ConversationOpenMessage): void {
+			openConversation(msg.conversationId);
+		},
 		onReopen() {
 			// The server forgot our subscriptions on reconnect; re-send each with the
 			// conversation it was subscribed under (protocolSubscribe would no-op since
diff --git a/src/core/wire/conformance.test.ts b/src/core/wire/conformance.test.ts
index 2fdd3cb..f5d6608 100644
--- a/src/core/wire/conformance.test.ts
+++ b/src/core/wire/conformance.test.ts
@@ -139,9 +139,18 @@ describe("classifies every WsServerMessage type", () => {
 				event: { type: "done" as const, conversationId: "c", turnId: "t", reason: "r" },
 			},
 			{ type: "chat.error" as const, message: "e" },
+			{ type: "conversation.open" as const, conversationId: "c1" },
 		];
 		const labels = msgs.map(assertWsServerMessageExhaustive);
-		expect(labels).toEqual(["catalog", "surface", "update", "error", "chat.delta", "chat.error"]);
+		expect(labels).toEqual([
+			"catalog",
+			"surface",
+			"update",
+			"error",
+			"chat.delta",
+			"chat.error",
+			"conversation.open",
+		]);
 	});
 });
 
diff --git a/src/core/wire/conformance.ts b/src/core/wire/conformance.ts
index 6e87e5c..05a15aa 100644
--- a/src/core/wire/conformance.ts
+++ b/src/core/wire/conformance.ts
@@ -81,6 +81,8 @@ export function assertWsServerMessageExhaustive(msg: WsServerMessage): string {
 			return "chat.delta";
 		case "chat.error":
 			return "chat.error";
+		case "conversation.open":
+			return "conversation.open";
 		default:
 			return msg satisfies never;
 	}