fix(acp): own deep-interview skill lifecycle end to end

packages/coding-agent/CHANGELOG.md

@@ -58,6 +58,7 @@
 - Slack Web API requests now use form encoding instead of JSON, preventing thread reconciliation through `conversations.replies` from failing with `invalid_arguments`.
 
 - Managed replacement cleanup now migrates version-one receipts from earlier releases and recovers canonical exchange placeholders left by interrupted cleanup, so a stale receipt cannot permanently block the next managed session mutation with `managed_replace_cleanup_receipt_invalid`.
+- ACP clients such as OpenCode can now map advertised `/skill:*` commands to canonical `skill.invoke` while binding the run to exact correlated prompt completion and cancellation ownership, and can answer deep-interview forms in headless lifecycle sessions. Lifecycle hosts initialize the shared theme before tools render and before the MCP readiness budget is calculated, preventing the pre-elicitation `theme.status` failure, and protocol form providers remain authoritative if a local `/notify on` registers an interactive source later.
 
 ## [0.12.11] - 2026-08-03
 

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

@@ -7,6 +7,7 @@ import type { Args as ParsedArgs } from "../cli/args";
 import { Settings } from "../config/settings";
 import { applyStartupModelProfiles, createSessionManager } from "../main";
 import { initializeExtensions } from "../modes/runtime-init";
+import { initTheme } from "../modes/theme/theme";
 import { ACP_MCP_REQUEST_TIMEOUT_MS, ACP_MCP_STARTUP_HEADROOM_MS } from "../sdk/acp/mcp";
 import { Broker } from "../sdk/broker/broker";
 import { readBrokerDiscovery } from "../sdk/broker/discovery";
@@ -387,6 +388,12 @@ export async function runSessionHost(
 			throw await registrationFailure(error);
 		}
 
+		try {
+			await initTheme(false);
+		} catch (error) {
+			throw await registrationFailure(error);
+		}
+
 		// The longer MCP startup ceiling is scoped to ACP lifecycle launches only:
 		// it applies when this request actually carried `mcpServers`. Ordinary
 		// CLI/SDK `mcpConfigPath` consumers keep the manager's short default.
@@ -395,8 +402,8 @@ export async function runSessionHost(
 		// Inside it, the throw would be caught, reclassified as
 		// `registration`/`failed`, and written a second time, losing the
 		// `startup`/`pending` outcome the readiness cutoff is supposed to report.
-		// Session-manager open and MCP config write already consumed part of the
-		// budget, so re-read the clock here rather than reusing the earlier check.
+		// Session-manager open, MCP config write, and theme initialization already
+		// consumed part of the budget, so re-read the clock here.
 		let mcpStartupTimeoutMs: number | undefined;
 		if (mcpConfigPath !== undefined) {
 			const remaining = request.semanticReadyDeadlineAt - now() - ACP_MCP_STARTUP_HEADROOM_MS;

packages/coding-agent/src/extensibility/extensions/runner.ts

@@ -621,7 +621,7 @@ export class ExtensionRunner {
 			setModelProfile: async name => (await this.#setModelProfileFn?.(name)) ?? false,
 			cycleThinkingLevel: () => this.#cycleThinkingLevelFn?.(),
 			setQueueMode: (kind, mode) => this.#setQueueModeFn?.(kind, mode) ?? false,
-			invokeSkill: async (name, args) => await this.#invokeSkillFn?.(name, args),
+			invokeSkill: async (name, args, options) => await this.#invokeSkillFn?.(name, args, options),
 
 			setPlanMode: on => this.#setPlanModeFn?.(on),
 			operateGoal: async (op, objective) => await this.#operateGoalFn?.(op, objective),

packages/coding-agent/src/extensibility/extensions/types.ts

@@ -412,6 +412,7 @@ export interface ExtensionContext {
 			onPreflightAccepted?: () => void;
 			onPreflightAcceptCommit?: () => void | Promise<void>;
 			onSkillPrepared?: (meta: { name: string; path: string; lineCount?: number; cleanedArgs?: string }) => void;
+			preflightSignal?: AbortSignal;
 		},
 	): Promise<unknown>;
 	setPlanMode?(on: boolean): unknown;
@@ -1511,6 +1512,7 @@ export interface ExtensionContextActions {
 			onPreflightAccepted?: () => void;
 			onPreflightAcceptCommit?: () => void | Promise<void>;
 			onSkillPrepared?: (meta: { name: string; path: string; lineCount?: number; cleanedArgs?: string }) => void;
+			preflightSignal?: AbortSignal;
 		},
 	) => Promise<unknown>;
 	setPlanMode?: (on: boolean) => unknown;

packages/coding-agent/src/modes/acp/acp-agent.ts

@@ -82,6 +82,8 @@ interface PromptWaiter {
 	terminal?: { outcome: SdkPromptTerminalOutcome; correlation: PromptCorrelation };
 	/** Frames for an already-settled correlation held until acknowledgement resolves ownership. */
 	deferredFrames: JsonObject[];
+	/** Coordinates a prompt-control rejection racing an acknowledged ACP cancellation. */
+	cancelAttempt?: Promise<boolean>;
 	resolve: (response: PromptResponse) => void;
 	reject: (error: Error) => void;
 }
@@ -646,6 +648,14 @@ export function acpSessionStateFromConfig(
 	};
 }
 
+/** Recognize an advertised ACP skill command only when it is the complete, single text prompt. */
+export function acpSkillInvocation(blocks: PromptRequest["prompt"]): { name: string; args: string } | undefined {
+	if (blocks.length !== 1 || blocks[0]?.type !== "text") return undefined;
+	const match = /^\/skill:([^\s]+)(?:\s+([\s\S]*))?$/.exec(blocks[0].text.trim());
+	if (!match?.[1]) return undefined;
+	return { name: match[1], args: match[2]?.trim() ?? "" };
+}
+
 /** Convert every ACP prompt block the agent advertises without silently discarding context. */
 export function acpPromptPayload(blocks: PromptRequest["prompt"]): {
 	text: string;
@@ -1121,6 +1131,7 @@ export class AcpAgent implements Agent {
 		if (record.activePrompt) throw new AcpSdkAdapterError("conflict", "ACP session already has an active prompt.");
 		if (record.authFailure) throw new AcpSdkAdapterError("authentication_failed", record.authFailure);
 		const payload = acpPromptPayload(params.prompt);
+		const skillInvocation = acpSkillInvocation(params.prompt);
 		let waiter!: PromptWaiter;
 		const response = new Promise<PromptResponse>((resolve, reject) => {
 			waiter = {
@@ -1136,10 +1147,12 @@ export class AcpAgent implements Agent {
 			record.activePrompt = waiter;
 		});
 		try {
-			const acknowledgement = await record.adapter.prompt({
-				text: payload.text,
-				...(payload.images.length ? { images: payload.images } : {}),
-			});
+			const acknowledgement = skillInvocation
+				? await record.adapter.control("skill.invoke", skillInvocation)
+				: await record.adapter.prompt({
+						text: payload.text,
+						...(payload.images.length ? { images: payload.images } : {}),
+					});
 			const acknowledgementCorrelation = promptAcknowledgement(acknowledgement);
 			if (!acknowledgementCorrelation)
 				throw new AcpSdkAdapterError(
@@ -1160,6 +1173,7 @@ export class AcpAgent implements Agent {
 					);
 			this.#settlePrompt(record, waiter);
 		} catch (error) {
+			if (waiter.cancelAttempt && (await waiter.cancelAttempt) && waiter.settled) return await response;
 			waiter.deferredFrames.length = 0;
 			waiter.terminal = undefined;
 			waiter.settled = true;
@@ -1172,13 +1186,35 @@ export class AcpAgent implements Agent {
 	async cancel(params: { sessionId: string }): Promise<void> {
 		const record = this.#sessions.get(params.sessionId);
 		if (!record) throw new AcpSdkAdapterError("not_found", `Unknown session, not found: ${params.sessionId}`);
-		const acknowledgement = await record.adapter.cancel();
-		const result = object(object(acknowledgement)?.result) ?? object(acknowledgement);
-		if (result?.aborted !== true)
-			throw new AcpSdkAdapterError(
-				"abort_unacknowledged",
-				"SDK did not acknowledge cancellation of the active prompt.",
-			);
+		const waiter = record.activePrompt;
+		const cancelAttempt = waiter ? Promise.withResolvers<boolean>() : undefined;
+		if (waiter && cancelAttempt) waiter.cancelAttempt = cancelAttempt.promise;
+		try {
+			const acknowledgement = await record.adapter.cancel();
+			const result = object(object(acknowledgement)?.result) ?? object(acknowledgement);
+			if (result?.aborted !== true)
+				throw new AcpSdkAdapterError(
+					"abort_unacknowledged",
+					"SDK did not acknowledge cancellation of the active prompt.",
+				);
+			if (
+				result.disposition === "preflight_cancelled" &&
+				waiter &&
+				record.activePrompt === waiter &&
+				!waiter.acknowledged &&
+				!waiter.settled
+			) {
+				record.activePrompt = undefined;
+				waiter.settled = true;
+				waiter.deferredFrames.length = 0;
+				waiter.terminal = undefined;
+				waiter.resolve({ stopReason: "cancelled" });
+			}
+			cancelAttempt?.resolve(true);
+		} catch (error) {
+			cancelAttempt?.resolve(false);
+			throw error;
+		}
 	}
 
 	async extMethod(method: string, params: JsonObject): Promise<JsonObject> {