feat(cli): add 'open' command to signal frontend without sending a message

dispatch open <conversationId> broadcasts a conversation.open WS message
to all connected frontend clients without sending any message. Useful
after 'read' or 'send --queue' when you just want the frontend to
open/focus a conversation's tab.

3 files changed, 71 insertions, 0 deletions

diff --git a/packages/cli/src/args.test.ts b/packages/cli/src/args.test.ts
index 70a4868..62bcafd 100644
--- a/packages/cli/src/args.test.ts
+++ b/packages/cli/src/args.test.ts
@@ -325,4 +325,35 @@ describe("parseArgs", () => {
 			expect(result.kind).toBe("error");
 		});
 	});
+
+	describe("open", () => {
+		it("parses 'open' with conversation id", () => {
+			expect(parseArgs(["open", "deadbeef"], { defaultServer })).toEqual({
+				kind: "open",
+				server: "http://localhost:24203",
+				conversationId: "deadbeef",
+			});
+		});
+
+		it("parses 'open' with --server", () => {
+			expect(
+				parseArgs(["open", "deadbeef", "--server", "http://example.com"], { defaultServer }),
+			).toEqual({
+				kind: "open",
+				server: "http://example.com",
+				conversationId: "deadbeef",
+			});
+		});
+
+		it("requires a conversation id", () => {
+			const result = parseArgs(["open"], { defaultServer });
+			expect(result.kind).toBe("error");
+			if (result.kind === "error") expect(result.message).toContain("conversation id");
+		});
+
+		it("rejects unknown flags", () => {
+			const result = parseArgs(["open", "deadbeef", "--bogus"], { defaultServer });
+			expect(result.kind).toBe("error");
+		});
+	});
 });
diff --git a/packages/cli/src/args.ts b/packages/cli/src/args.ts
index 4d6652e..d4ed0e9 100644
--- a/packages/cli/src/args.ts
+++ b/packages/cli/src/args.ts
@@ -28,6 +28,7 @@ export type ParsedCommand =
 			readonly open: boolean;
 	  }
 	| { readonly kind: "list"; readonly server: string; readonly query?: string }
+	| { readonly kind: "open"; readonly server: string; readonly conversationId: string }
 	| { readonly kind: "read"; readonly server: string; readonly conversationId: string }
 	| {
 			readonly kind: "send";
@@ -110,6 +111,28 @@ export function parseArgs(argv: readonly string[], opts: ParseOpts): ParsedComma
 		return { kind: "read", server, conversationId };
 	}
 
+	if (first === "open") {
+		let server = opts.defaultServer;
+		let conversationId: string | undefined;
+		for (let i = 1; i < argv.length; i++) {
+			const arg = argv[i] as string;
+			if (arg === "--server") {
+				if (i + 1 >= argv.length) return { kind: "error", message: "--server requires a value" };
+				server = argv[++i] as string;
+			} else if (arg.startsWith("--")) {
+				return { kind: "error", message: `Unknown flag: ${arg}` };
+			} else if (conversationId !== undefined) {
+				return { kind: "error", message: `Unexpected argument for 'open': ${arg}` };
+			} else {
+				conversationId = arg;
+			}
+		}
+		if (conversationId === undefined) {
+			return { kind: "error", message: "'open' requires a conversation id" };
+		}
+		return { kind: "open", server, conversationId };
+	}
+
 	if (first === "send") {
 		let server = opts.defaultServer;
 		let conversationId: string | undefined;
diff --git a/packages/cli/src/main.ts b/packages/cli/src/main.ts
index 04e7231..365096a 100644
--- a/packages/cli/src/main.ts
+++ b/packages/cli/src/main.ts
@@ -24,6 +24,7 @@ const USAGE = `Usage:
   dispatch models [--server <url>]
   dispatch list [<prefix>] [--server <url>]
   dispatch read <conversationId> [--server <url>]
+  dispatch open <conversationId> [--server <url>]
   dispatch send <conversationId> --text "..." [--queue] [--open] [--cwd <dir>] [--effort <level>] [--server <url>]
   dispatch <modelName> --text "..." [--file <path>] [--cwd <dir>] [--conversation <id>] [--effort <level>] [--server <url>] [--show-reasoning] [--open]
   dispatch --help
@@ -73,6 +74,22 @@ async function main(): Promise<void> {
 			if (last.content.length > 0) process.stdout.write(`${last.content}\n`);
 			break;
 		}
+		case "open": {
+			const resolved = await resolveConversationId(
+				{ fetchImpl: globalThis.fetch },
+				{ server: parsed.server, shortId: parsed.conversationId },
+			);
+			if (typeof resolved !== "string") {
+				process.stderr.write(`${resolved.error}\n`);
+				process.exit(1);
+			}
+			await openConversation(
+				{ fetchImpl: globalThis.fetch },
+				{ server: parsed.server, conversationId: resolved },
+			);
+			process.stdout.write(`Signaled frontend to open ${resolved}\n`);
+			break;
+		}
 		case "send": {
 			const resolved = await resolveConversationId(
 				{ fetchImpl: globalThis.fetch },