fix(sdk): stop Slack/Discord chat daemons from publishing lean finals twice

packages/coding-agent/changelog.d/lean-final-answer-publication-dedupe.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- Slack and Discord chat daemons no longer post every lean final answer twice. The host sends each turn frame on a positioned leg and a raw leg and drops the raw copy only for connections that negotiate `positioned_notification_effects_v1`; the chat daemons' session connections never did, and a lean final carries no `messageRef` to collapse the two copies onto one publication. Chat daemon session connections now negotiate positioned-only notification effects, while plain SDK observers such as `gjc sdk session tail` keep both surfaces.

packages/coding-agent/src/sdk/bus/chat-daemon-control.ts

@@ -141,8 +141,8 @@ export type ChatDaemonAction = "stop" | "reload";
  * crashes, recovery, and attachment retirement cannot replay ambiguous work.
  */
 export const CHAT_DAEMON_GENERATIONS: Readonly<Record<ChatDaemonKind, number>> = {
-	discord: 82,
-	slack: 89,
+	discord: 83,
+	slack: 90,
 };
 
 export function chatDaemonGeneration(kind: ChatDaemonKind): number {

packages/coding-agent/src/sdk/bus/chat-daemon-runtime.ts

@@ -318,6 +318,9 @@ export class ChatDaemonRuntime {
 		this.#router = new SessionRouter({
 			agentDir: input.agentDir,
 			observer: true,
+			// A lean final answer carries no messageRef, so the raw native copy of a
+			// positioned frame has no identity to collapse onto and would post twice.
+			positionedNotificationEffects: true,
 			correlateFrame,
 			deps: {
 				...deps.routerDeps,

packages/coding-agent/src/sdk/bus/index.ts

@@ -105,6 +105,7 @@ import {
 	canDeliverSdkEvent,
 	createSdkSurfaceFactory,
 	masterAttestationForEffectiveHost,
+	POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY,
 	reattestMasterSessionIdentity,
 	SESSION_HOST_OBSERVER_CAPABILITY,
 	type SessionSdkHost,
@@ -204,7 +205,6 @@ import {
 	ASK_SELECTED_ACK_CAPABILITY,
 	type EnsureDaemonResult,
 	ensureTelegramDaemonRunningDetailed,
-	POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY,
 } from "./telegram-daemon";
 
 export type {

packages/coding-agent/src/sdk/bus/telegram-daemon.ts

@@ -71,6 +71,7 @@ export {
 	TELEGRAM_TRANSPORT_GENERATION,
 } from "./telegram-daemon-contract";
 
+import { POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY } from "../host/host";
 import {
 	type AgentDirSessionLifecycleService,
 	createSessionLifecycleService,
@@ -303,8 +304,9 @@ export const ASK_CONTROLS_CAPABILITY = "ask_controls_v1";
 export const TOOL_ACTIVITY_CAPABILITY = "tool_activity_v2";
 /** Receive-only compatibility capability for pre-v2 hosts. */
 export const LEGACY_TOOL_ACTIVITY_CAPABILITY = "tool_activity_v1";
-/** Opts notification adapters into positioned-only delivery for matching live effects. */
-export const POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY = "positioned_notification_effects_v1";
+/** Public `sdk/bus/telegram-daemon` path for the canonical `sdk/host` capability token. */
+export { POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY };
+
 type ToolActivityCapability = "v1" | "v2";
 
 function negotiateToolActivityCapability(

packages/coding-agent/src/sdk/host/host.ts

@@ -107,6 +107,12 @@ export const TOOL_ACTIVITY_CAPABILITY = "tool_activity_v2";
 export const TURN_STREAM_CAPABILITY = "turn_stream";
 /** Capability used by notification adapters that observe a host without owning its work. */
 export const SESSION_HOST_OBSERVER_CAPABILITY = "session_host_observer_v1";
+/**
+ * Opts notification adapters into positioned-only delivery for matching live
+ * effects: the host excludes a negotiating connection from the raw native leg
+ * of every frame its positioned envelope already reached.
+ */
+export const POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY = "positioned_notification_effects_v1";
 export const CAP_GATED_FRAME_KINDS: ReadonlySet<string> = new Set(["tool_activity", "reasoning_summary"]);
 const EMPTY_CAPABILITIES: ReadonlySet<string> = new Set();
 

packages/coding-agent/src/sdk/router/session-router.ts

@@ -25,7 +25,11 @@ import {
 	readSdkSessionEndpoint,
 	type SdkSessionEndpoint,
 } from "../client/discovery";
-import { SESSION_HOST_OBSERVER_CAPABILITY, TURN_STREAM_CAPABILITY } from "../host/host";
+import {
+	POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY,
+	SESSION_HOST_OBSERVER_CAPABILITY,
+	TURN_STREAM_CAPABILITY,
+} from "../host/host";
 import {
 	type ActivatedPreparedSession,
 	type PreparedSessionActivationClient,
@@ -291,6 +295,13 @@ export interface SessionRouterOptions {
 	attachFilter?: (sessionId: string) => boolean;
 	/** Marks default SDK clients as notification-only observers; demanding by default. */
 	observer?: boolean;
+	/**
+	 * Negotiates positioned-only notification effects on default SDK clients, so the
+	 * host stops sending them the raw native copy of frames whose positioned
+	 * envelope already reached them. Only notification-effect publishers opt in;
+	 * ordinary SDK observers keep both public surfaces.
+	 */
+	positionedNotificationEffects?: boolean;
 	deps?: SessionRouterDeps;
 	/** Runtime-specific identity validation; Router supplies a conservative fallback. */
 	correlateFrame?: SessionRouterFrameCorrelator;
@@ -619,6 +630,7 @@ export class SessionRouter {
 	readonly #sessionIds: ReadonlySet<string> | undefined;
 	readonly #attachFilter: ((sessionId: string) => boolean) | undefined;
 	readonly #observer: boolean;
+	readonly #positionedNotificationEffects: boolean;
 	readonly #deps: SessionRouterDeps;
 	readonly #correlateFrame: SessionRouterFrameCorrelator;
 	readonly #index: SessionIndex;
@@ -662,6 +674,7 @@ export class SessionRouter {
 		this.#sessionIds = options.sessionIds === undefined ? undefined : new Set(options.sessionIds);
 		this.#attachFilter = options.attachFilter;
 		this.#observer = options.observer === true;
+		this.#positionedNotificationEffects = options.positionedNotificationEffects === true;
 		this.#deps = options.deps ?? {};
 		this.#correlateFrame = options.correlateFrame ?? fallbackCorrelation;
 		this.#index = this.#deps.createIndex?.(options.agentDir) ?? new DefaultSessionIndex(options.agentDir);
@@ -1530,9 +1543,13 @@ export class SessionRouter {
 				endpointMtimeMs,
 			});
 		} else {
+			const capabilities = [
+				...(this.#observer ? [SESSION_HOST_OBSERVER_CAPABILITY, TURN_STREAM_CAPABILITY] : []),
+				...(this.#positionedNotificationEffects ? [POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY] : []),
+			];
 			const defaultClient = new SdkClient(endpoint.url, endpoint.token, {
 				...ACP_SESSION_RECONNECT,
-				...(this.#observer ? { capabilities: [SESSION_HOST_OBSERVER_CAPABILITY, TURN_STREAM_CAPABILITY] } : {}),
+				...(capabilities.length > 0 ? { capabilities } : {}),
 			});
 			transport = defaultClient;
 			connection = defaultClient.connect().then(() => defaultClient);

packages/coding-agent/test/notifications-turn-ordering.test.ts

@@ -3,7 +3,8 @@ import * as fs from "node:fs";
 import * as os from "node:os";
 import * as path from "node:path";
 import { createNotificationsExtension } from "../src/sdk/bus/index";
-import { POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY, TOOL_ACTIVITY_CAPABILITY } from "../src/sdk/bus/telegram-daemon";
+import { TOOL_ACTIVITY_CAPABILITY } from "../src/sdk/bus/telegram-daemon";
+import { POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY } from "../src/sdk/host/host";
 import {
 	cleanupFixtureRoots,
 	createNotificationFixtureRoot,

packages/coding-agent/test/sdk-chat-daemon-worker.test.ts

@@ -265,6 +265,96 @@ class FakeSdkClient implements SessionRouterClient {
 	}
 }
 
+/**
+ * Drives one lean final answer through the production host into a real chat
+ * runtime and returns how many provider posts carry it. The host emits every
+ * turn_stream on a positioned leg and a raw native leg, excluding from the raw
+ * leg only connections that negotiated positioned-only notification effects. A
+ * lean final carries no messageRef, so a daemon that receives both legs has no
+ * shared identity to collapse them into one post.
+ */
+async function deliverLeanFinalThroughProductionHost(
+	root: string,
+	kind: "slack" | "discord",
+	finalText: string,
+): Promise<number> {
+	const agentDir = path.join(root, ".gjc", "agent");
+	const host = await startProductionSdkHost(root);
+	const index = await new SessionIndex(agentDir).open();
+	const slackProvider = new FakeSlackProvider();
+	const discordProvider = new FakeDiscordProvider();
+	const notifications =
+		kind === "slack"
+			? {
+					slack: {
+						botToken: "bot-token",
+						appToken: "app-token",
+						workspaceId: "team",
+						channelId: "channel",
+						authorizedUserId: "human",
+					},
+				}
+			: {
+					discord: {
+						botToken: "discord-token",
+						applicationId: discordProvider.applicationId,
+						guildId: "guild",
+						parentChannelId: "parent",
+					},
+				};
+	const runtime = new ChatDaemonRuntime(
+		{
+			kind,
+			agentDir,
+			config: { identity: "fingerprint-only", presentation: { redact: false, verbosity: "lean" }, notifications },
+		},
+		{
+			createSlackProvider: () => slackProvider,
+			createDiscordProvider: () => discordProvider,
+			routerDeps: {
+				createIndex: () => index,
+				setInterval: (() => 0) as unknown as typeof setInterval,
+				clearInterval: (() => {}) as typeof clearInterval,
+			},
+		},
+	);
+	const count = (): number =>
+		kind === "slack"
+			? slackProvider.posts.filter(post => post.text.includes(finalText)).length
+			: discordProvider.messages.filter(message => message.content.includes(finalText)).length;
+	try {
+		await index.append({
+			type: "host_registered",
+			sessionId: host.sessionId,
+			locator: { cwd: root, worktreeRoot: null, stateRoot: path.join(root, ".gjc", "state") },
+			endpointGeneration: 1,
+			pid: host.endpoint.pid,
+			endpointMtimeMs: host.endpointMtimeMs,
+		});
+		await withStageTimeout(`${kind} runtime start`, runtime.start());
+		await withStageTimeout(`${kind} runtime admission`, runtime.reconcile({ waitForReplay: true }));
+		const runner = host.session.extensionRunner;
+		const assistant = { role: "assistant", content: finalText };
+		await runner?.emit({ type: "agent_start" });
+		await runner?.emit({ type: "message_end", message: assistant } as never);
+		await runner?.emit({ type: "turn_end", turnIndex: 0, message: assistant } as never);
+		await runner?.emit({
+			type: "agent_end",
+			stopReason: "completed",
+			messages: [{ role: "assistant", stopReason: "stop" }],
+		} as never);
+		const deadline = Date.now() + 10_000;
+		while (count() < 1 && Date.now() < deadline) await Bun.sleep(10);
+		// Both host legs land within milliseconds; leave room for a second
+		// representation to arrive before asserting that it never does.
+		await Bun.sleep(500);
+		await withStageTimeout(`${kind} runtime stop`, runtime.stop());
+	} finally {
+		await withStageTimeout("production SDK host stop", host.stop());
+	}
+	return count();
+}
+
 describe("chat daemon worker", () => {
 	let root = "";
 	afterEach(async () => {
@@ -1709,4 +1799,24 @@ describe("chat daemon worker", () => {
 		},
 		60_000,
 	);
+
+	it.skipIf(skipProductionSessionHost)(
+		"posts a lean final answer from the production host to Slack exactly once",
+		async () => {
+			root = await fs.mkdtemp(path.join(process.env.TMPDIR ?? "/tmp", "gjc-slack-lean-final-"));
+			const posts = await deliverLeanFinalThroughProductionHost(root, "slack", "Lean Slack final answer.");
+			expect(posts).toBe(1);
+		},
+		60_000,
+	);
+
+	it.skipIf(skipProductionSessionHost)(
+		"posts a lean final answer from the production host to Discord exactly once",
+		async () => {
+			root = await fs.mkdtemp(path.join(process.env.TMPDIR ?? "/tmp", "gjc-discord-lean-final-"));
+			const posts = await deliverLeanFinalThroughProductionHost(root, "discord", "Lean Discord final answer.");
+			expect(posts).toBe(1);
+		},
+		60_000,
+	);
 });

packages/coding-agent/test/sdk-host-wiring.test.ts

@@ -75,7 +75,11 @@ import { getTelegramFileSink } from "../src/sdk/bus/attachment-registry";
 import { reconciliationStorePath } from "../src/sdk/bus/reconciliation-store";
 import type { NotificationSessionController } from "../src/sdk/bus/session-control";
 import { SdkClient } from "../src/sdk/client";
-import { SESSION_HOST_OBSERVER_CAPABILITY, SessionSdkHost } from "../src/sdk/host";
+import {
+	POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY,
+	SESSION_HOST_OBSERVER_CAPABILITY,
+	SessionSdkHost,
+} from "../src/sdk/host";
 import { createSdkRunCapability } from "../src/sdk/host/sdk-run-capability";
 import { type SessionAttachment, SessionRouter } from "../src/sdk/router/session-router";
 import { createAgentSession } from "../src/sdk/session";
@@ -1282,6 +1286,53 @@ test("a default ACP-shaped SessionRouter client remains demanding", async () =>
 	}
 }, 60_000);
 
+test("only a positioned-effects SessionRouter negotiates positioned-only notification delivery", async () => {
+	const negotiations: string[][] = [];
+	const negotiatedImpl = NotificationServer.prototype.onNegotiatedCapabilities;
+	const negotiatedHook = spyOn(NotificationServer.prototype, "onNegotiatedCapabilities").mockImplementation(function (
+		this: NotificationServer,
+		callback,
+	) {
+		return negotiatedImpl.call(this, (error, connectionId, capabilities) => {
+			// The threadsafe callback delivers its tuple as the second argument at runtime.
+			const negotiated = Array.isArray(connectionId) ? (connectionId as unknown[])[1] : capabilities;
+			if (Array.isArray(negotiated)) negotiations.push(negotiated.map(String));
+			return callback(error, connectionId, capabilities);
+		});
+	});
+	const cwd = fs.mkdtempSync(path.join(os.tmpdir(), "gjc-sdk-router-positioned-effects-"));
+	dirs.push(cwd);
+	const agentDir = path.join(cwd, ".gjc", "agent");
+	let host: Awaited<ReturnType<typeof startProductionSdkHost>> | undefined;
+	try {
+		host = await startProductionSdkHost(cwd, { acceptPromptPreflightWithoutExecution: true });
+		// A plain observer (e.g. `sdk session tail`) keeps both public surfaces (#4570).
+		const observer = new SessionRouter({ agentDir, observer: true });
+		try {
+			await observer.start();
+			await waitFor(() => negotiations.length === 1, "plain observer hello negotiation");
+		} finally {
+			await observer.stop();
+		}
+		expect(negotiations[0]).toContain(SESSION_HOST_OBSERVER_CAPABILITY);
+		expect(negotiations[0]).not.toContain(POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY);
+
+		const publisher = new SessionRouter({ agentDir, observer: true, positionedNotificationEffects: true });
+		try {
+			await publisher.start();
+			await waitFor(() => negotiations.length === 2, "positioned-effects hello negotiation");
+		} finally {
+			await publisher.stop();
+		}
+		expect(negotiations[1]).toEqual(
+			expect.arrayContaining([SESSION_HOST_OBSERVER_CAPABILITY, POSITIONED_NOTIFICATION_EFFECTS_CAPABILITY]),
+		);
+	} finally {
+		await host?.stop();
+		negotiatedHook.mockRestore();
+	}
+}, 60_000);
+
 test("late capability and replay callbacks after close cannot erase a live demanding client", async () => {
 	let negotiated: Parameters<NotificationServer["onNegotiatedCapabilities"]>[0] | undefined;
 	let closed: Parameters<NotificationServer["onConnectionClose"]>[0] | undefined;

scripts/telegram-daemon-generation-manifest.json

@@ -355,7 +355,7 @@
     "discord:packages/coding-agent/src/sdk/bus/chat-daemon-cli.ts:loadConfig": "aff409ff6d08bfe19f5c39aac900ec6c8e898d988971bac029edb50459a84f5e",
     "discord:packages/coding-agent/src/sdk/bus/chat-daemon-cli.ts:ownerPid": "31110dcdd6e0f5dbc8b4dce27383646b9c339739758623ab67dc40ddc36661e0",
     "discord:packages/coding-agent/src/sdk/bus/chat-daemon-cli.ts:runChatDaemonInternal": "75b90374711fb7060161007debc1907e1e9a919ac9e89c46ab0c55542ee2f43d",
-    "discord:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:CHAT_DAEMON_GENERATIONS.discord": "a8859a9326999dafd1c5e3ca2304992432b79152f58c9cdf2922a78217e67e66",
+    "discord:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:CHAT_DAEMON_GENERATIONS.discord": "5d09346b12df473a4abc8dc4d9e8d28bc5b3704ffc429be131b8fa7856715094",
     "discord:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:ChatDaemonAction": "d8acaf90439e410595b5cd56fd187001393ea943517a5563a4a2ea3c88d155ef",
     "discord:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:ChatDaemonController": "bb722a6a83eb383fce45e756cba356592b33ff0f505b4263409ce9138ea651f1",
     "discord:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:ChatDaemonKind": "b1c2906c4eb04e120c9ce42f8b549a68cfc834d29d4d745335712a7f61bf09f2",
@@ -433,13 +433,13 @@
     "discord:packages/coding-agent/src/sdk/bus/discord-daemon.ts:stop": "c8bcd881cc0331fb0565a82d997805f939701b12a80e03177192dbd5935824ff",
     "discord:packages/coding-agent/src/sdk/client/discovery.ts:readSdkSessionEndpoint": "bd8efa5f581993b3dc6c5549f62732211181b460b6e38d97220bb77b1875075e",
     "discord:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#attach": "a08b206ed46659b003ff331708cfccdf81c5c3037263bacca71d675fd09321e3",
-    "discord:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#createAttachedClient": "76a3018aaf6f9b1dec802a884cb1e40c16a9c9b5ae5b842a70c1fc01c3cf53eb",
+    "discord:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#createAttachedClient": "f7d9879aeb8e84d4b4090567694b8332fdea95b25a79614e639a313dfd00fc87",
     "discord:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#publishAttachment": "d46fff88a22ebd42e3e439a5cc20059a2ed002945972849e841a2e7d644a3079",
     "slack:packages/coding-agent/src/sdk/bus/chat-daemon-cli.ts:defaultPidAlive": "437658a2f14ac5daa2a3e84dcd637078566e71a88841cd750efab6d48fc94c3f",
     "slack:packages/coding-agent/src/sdk/bus/chat-daemon-cli.ts:loadConfig": "aff409ff6d08bfe19f5c39aac900ec6c8e898d988971bac029edb50459a84f5e",
     "slack:packages/coding-agent/src/sdk/bus/chat-daemon-cli.ts:ownerPid": "31110dcdd6e0f5dbc8b4dce27383646b9c339739758623ab67dc40ddc36661e0",
     "slack:packages/coding-agent/src/sdk/bus/chat-daemon-cli.ts:runChatDaemonInternal": "75b90374711fb7060161007debc1907e1e9a919ac9e89c46ab0c55542ee2f43d",
-    "slack:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:CHAT_DAEMON_GENERATIONS.slack": "dcf417b4588584fa316a85fdae4ca5df3775fba4fde23ad36764a66577193536",
+    "slack:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:CHAT_DAEMON_GENERATIONS.slack": "560f9edb3556499911a859bc2a1c3dc6dcf927da2674c46be409d5ee3cf46086",
     "slack:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:ChatDaemonAction": "d8acaf90439e410595b5cd56fd187001393ea943517a5563a4a2ea3c88d155ef",
     "slack:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:ChatDaemonController": "bb722a6a83eb383fce45e756cba356592b33ff0f505b4263409ce9138ea651f1",
     "slack:packages/coding-agent/src/sdk/bus/chat-daemon-control.ts:ChatDaemonKind": "b1c2906c4eb04e120c9ce42f8b549a68cfc834d29d4d745335712a7f61bf09f2",
@@ -518,7 +518,7 @@
     "slack:packages/coding-agent/src/sdk/bus/slack-daemon.ts:stop": "4ec3502bc5b1fc192a44a9f53f5d19d56190be51b5b285c171bc97441487dbf5",
     "slack:packages/coding-agent/src/sdk/client/discovery.ts:readSdkSessionEndpoint": "bd8efa5f581993b3dc6c5549f62732211181b460b6e38d97220bb77b1875075e",
     "slack:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#attach": "a08b206ed46659b003ff331708cfccdf81c5c3037263bacca71d675fd09321e3",
-    "slack:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#createAttachedClient": "76a3018aaf6f9b1dec802a884cb1e40c16a9c9b5ae5b842a70c1fc01c3cf53eb",
+    "slack:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#createAttachedClient": "f7d9879aeb8e84d4b4090567694b8332fdea95b25a79614e639a313dfd00fc87",
     "slack:packages/coding-agent/src/sdk/router/session-router.ts:SessionRouter.#publishAttachment": "d46fff88a22ebd42e3e439a5cc20059a2ed002945972849e841a2e7d644a3079",
     "telegram:packages/coding-agent/src/sdk/bus/config.ts:isTelegramSessionEligible": "6e2bf01ec7f58e07658172a2911741891f4eb05e2050e536bc170d6770746c37",
     "telegram:packages/coding-agent/src/sdk/bus/config.ts:parseNotificationSettingsSnapshot": "a694158726a9a4f4df58d1b1a4cee54884ef2e4bab506b3c6cac981b3f41072e",