diff --git a/package-lock.json b/package-lock.json
index 3298dda2..0c9e514e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,7 @@
       "version": "0.0.46",
       "license": "Apache-2.0",
       "dependencies": {
-        "@agentclientprotocol/sdk": "^0.22.1",
+        "@agentclientprotocol/sdk": "^0.25.1",
         "@openai/codex": "^0.139.0",
         "diff": "^8.0.3",
         "open": "^11.0.0",
@@ -28,9 +28,9 @@
       }
     },
     "node_modules/@agentclientprotocol/sdk": {
-      "version": "0.22.1",
-      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-0.22.1.tgz",
-      "integrity": "sha512-DfqXtl/8gO9NImq094MTaCXEU2vkhh6v7q/kT+9UjZxUqj8hYaya2OjLVIqn16MzNHcXEpShTR2RIauLSYeDQQ==",
+      "version": "0.25.1",
+      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-0.25.1.tgz",
+      "integrity": "sha512-jx2rF3bdpGwZ75Q/meyEDLLbYmbtxk82Uh9hDCdxDvcEedBnNSF5hZAnL/kJR5VNz56JqwOmqnAqasC84MwwkQ==",
       "license": "Apache-2.0",
       "peerDependencies": {
         "zod": "^3.25.0 || ^4.0.0"
diff --git a/package.json b/package.json
index 57d80385..73b2ed67 100644
--- a/package.json
+++ b/package.json
@@ -61,7 +61,7 @@
     "vitest": "^4.0.10"
   },
   "dependencies": {
-    "@agentclientprotocol/sdk": "^0.22.1",
+    "@agentclientprotocol/sdk": "^0.25.1",
     "@openai/codex": "^0.139.0",
     "diff": "^8.0.3",
     "open": "^11.0.0",
diff --git a/src/AcpExtensions.ts b/src/AcpExtensions.ts
index 13780134..5d411d2f 100644
--- a/src/AcpExtensions.ts
+++ b/src/AcpExtensions.ts
@@ -1,11 +1,68 @@
-export type ExtMethodRequest = AuthenticationStatusRequest | AuthenticationLogoutRequest
+import type {
+    ClientSideConnection,
+    LoadSessionResponse,
+    NewSessionResponse,
+    ResumeSessionResponse,
+    SessionId,
+} from "@agentclientprotocol/sdk";
+
+export const LEGACY_SET_SESSION_MODEL_METHOD = "session/set_model";
+
+export type LegacySessionModel = {
+    modelId: string;
+    name: string;
+    description?: string | null;
+}
+
+export type LegacySessionModelState = {
+    availableModels: Array<LegacySessionModel>;
+    currentModelId: string;
+}
+
+export type LegacySetSessionModelRequest = {
+    sessionId: SessionId;
+    modelId: string;
+}
+
+export type LegacySetSessionModelResponse = {}
+
+export type LegacyNewSessionResponse = NewSessionResponse & {
+    models?: LegacySessionModelState | null;
+}
+
+export type LegacyLoadSessionResponse = LoadSessionResponse & {
+    models?: LegacySessionModelState | null;
+}
+
+export type LegacyResumeSessionResponse = ResumeSessionResponse & {
+    models?: LegacySessionModelState | null;
+}
+
+export type ExtMethodRequest =
+    AuthenticationStatusRequest
+    | AuthenticationLogoutRequest
+    | LegacySetSessionModelExtRequest
 
 export function isExtMethodRequest(request: { method: string, params: Record<string, unknown> }): request is ExtMethodRequest {
-    return request.method === "authentication/status" || request.method === "authentication/logout";
+    return request.method === "authentication/status"
+        || request.method === "authentication/logout"
+        || request.method === LEGACY_SET_SESSION_MODEL_METHOD;
 }
 
 export type AuthenticationStatusRequest = { method: "authentication/status", params: {} }
 export type AuthenticationStatusResponse = { type: "api-key" } | { type: "chat-gpt", email: string } | { type: "gateway", name: string } | { type: "unauthenticated" }
 
 export type AuthenticationLogoutRequest = { method: "authentication/logout", params: {} }
-export type AuthenticationLogoutResponse = {}
\ No newline at end of file
+export type AuthenticationLogoutResponse = {}
+
+export type LegacySetSessionModelExtRequest = {
+    method: typeof LEGACY_SET_SESSION_MODEL_METHOD;
+    params: LegacySetSessionModelRequest;
+}
+
+export async function legacySetSessionModel(
+    connection: Pick<ClientSideConnection, "extMethod">,
+    params: LegacySetSessionModelRequest,
+): Promise<LegacySetSessionModelResponse> {
+    return await connection.extMethod(LEGACY_SET_SESSION_MODEL_METHOD, params) as LegacySetSessionModelResponse;
+}
diff --git a/src/CodexAcpServer.ts b/src/CodexAcpServer.ts
index 89d25842..95b9cc0d 100644
--- a/src/CodexAcpServer.ts
+++ b/src/CodexAcpServer.ts
@@ -1,5 +1,5 @@
 import * as acp from "@agentclientprotocol/sdk";
-import {RequestError, type SessionId, type SessionModelState, type SessionModeState} from "@agentclientprotocol/sdk";
+import {RequestError, type SessionId, type SessionModeState} from "@agentclientprotocol/sdk";
 import {CodexEventHandler} from "./CodexEventHandler";
 import {CodexApprovalHandler} from "./CodexApprovalHandler";
 import {CodexElicitationHandler} from "./CodexElicitationHandler";
@@ -33,7 +33,16 @@ import {CodexCommands} from "./CodexCommands";
 import type {QuotaMeta} from "./QuotaMeta";
 import {logger} from "./Logger";
 import {sanitizeMcpServerName} from "./McpServerName";
-import {isExtMethodRequest} from "./AcpExtensions";
+import {
+    type LegacyLoadSessionResponse,
+    type LegacyNewSessionResponse,
+    type LegacyResumeSessionResponse,
+    type LegacySessionModelState,
+    type LegacySetSessionModelRequest,
+    type LegacySetSessionModelResponse,
+    isExtMethodRequest,
+    LEGACY_SET_SESSION_MODEL_METHOD,
+} from "./AcpExtensions";
 import {
     createCommandExecutionUpdate,
     createDynamicToolCallUpdate,
@@ -189,9 +198,11 @@ export class CodexAcpServer implements acp.Agent {
             case "authentication/status":
                 return await this.runWithProcessCheck(() => this.codexAcpClient.getAuthenticationStatus());
             case "authentication/logout": {
-                await this.unstable_logout({});
+                await this.logout({});
                 return {};
             }
+            case LEGACY_SET_SESSION_MODEL_METHOD:
+                return await this.unstable_setSessionModel(this.parseLegacySetSessionModelParams(methodRequest.params));
         }
     }
 
@@ -212,7 +223,7 @@ export class CodexAcpServer implements acp.Agent {
         }
     }
 
-    async getOrCreateSession(request: acp.NewSessionRequest | acp.ResumeSessionRequest): Promise<[SessionId, SessionModelState, SessionModeState]> {
+    async getOrCreateSession(request: acp.NewSessionRequest | acp.ResumeSessionRequest): Promise<[SessionId, LegacySessionModelState, SessionModeState]> {
         try {
             return await this.tryCreateSession(request);
         } catch (e) {
@@ -292,7 +303,7 @@ export class CodexAcpServer implements acp.Agent {
         return generation;
     }
 
-    async tryCreateSession(request: acp.NewSessionRequest | acp.ResumeSessionRequest): Promise<[SessionId, SessionModelState, SessionModeState]> {
+    async tryCreateSession(request: acp.NewSessionRequest | acp.ResumeSessionRequest): Promise<[SessionId, LegacySessionModelState, SessionModeState]> {
         const requestedSessionGeneration = "sessionId" in request
             ? this.beginSessionOpen(request.sessionId)
             : null;
@@ -372,7 +383,7 @@ export class CodexAcpServer implements acp.Agent {
         }
 
         this.publishAvailableCommandsAsync(sessionId);
-        const sessionModelState: SessionModelState = this.createModelState(models, currentModelId);
+        const sessionModelState: LegacySessionModelState = this.createModelState(models, currentModelId);
         const sessionModeState: SessionModeState = sessionState.agentMode.toSessionModeState();
 
         return [sessionId, sessionModelState, sessionModeState];
@@ -386,7 +397,7 @@ export class CodexAcpServer implements acp.Agent {
         return accountResponse.account;
     }
 
-    async loadSession(params: acp.LoadSessionRequest): Promise<acp.LoadSessionResponse> {
+    async loadSession(params: acp.LoadSessionRequest): Promise<LegacyLoadSessionResponse> {
         logger.log("Loading session...", {sessionId: params.sessionId});
         const {
             sessionId,
@@ -409,7 +420,7 @@ export class CodexAcpServer implements acp.Agent {
         };
     }
 
-    async resumeSession(params: acp.ResumeSessionRequest): Promise<acp.ResumeSessionResponse> {
+    async resumeSession(params: acp.ResumeSessionRequest): Promise<LegacyResumeSessionResponse> {
         logger.log("Resuming session...", {sessionId: params.sessionId});
         const [sessionId, modelState, modeState] = await this.getOrCreateSession(params);
 
@@ -465,7 +476,7 @@ export class CodexAcpServer implements acp.Agent {
         return {};
     }
 
-    async unstable_deleteSession(params: acp.DeleteSessionRequest): Promise<acp.DeleteSessionResponse> {
+    async deleteSession(params: acp.DeleteSessionRequest): Promise<acp.DeleteSessionResponse> {
         logger.log("Deleting session...", {sessionId: params.sessionId});
         const sessionId = params.sessionId;
         const shouldCloseLocalSession = this.hasLocalSession(sessionId);
@@ -502,7 +513,7 @@ export class CodexAcpServer implements acp.Agent {
 
     async newSession(
         params: acp.NewSessionRequest,
-    ): Promise<acp.NewSessionResponse> {
+    ): Promise<LegacyNewSessionResponse> {
         logger.log("Starting new session...");
         const [sessionId, modelState, modeState] = await this.getOrCreateSession(params);
 
@@ -533,7 +544,7 @@ export class CodexAcpServer implements acp.Agent {
         return { };
     }
 
-    async unstable_logout(_params: acp.LogoutRequest): Promise<void> {
+    async logout(_params: acp.LogoutRequest): Promise<void> {
         logger.log("Logout request received");
         await this.runWithProcessCheck(() => this.codexAcpClient.logout());
         logger.log("Logout request completed");
@@ -630,7 +641,7 @@ export class CodexAcpServer implements acp.Agent {
         sessionState.currentModelSupportsFast = modelSupportsFast(model);
     }
 
-    async unstable_setSessionModel(params: acp.SetSessionModelRequest): Promise<acp.SetSessionModelResponse | void> {
+    async unstable_setSessionModel(params: LegacySetSessionModelRequest): Promise<LegacySetSessionModelResponse> {
         logger.log("Set session model requested", {
             sessionId: params.sessionId,
             modelId: params.modelId
@@ -661,6 +672,18 @@ export class CodexAcpServer implements acp.Agent {
         return {};
     }
 
+    private parseLegacySetSessionModelParams(params: Record<string, unknown>): LegacySetSessionModelRequest {
+        const sessionId = params["sessionId"];
+        const modelId = params["modelId"];
+        if (typeof sessionId !== "string" || typeof modelId !== "string") {
+            throw RequestError.invalidParams();
+        }
+        return {
+            sessionId: sessionId,
+            modelId: modelId,
+        };
+    }
+
     private createSessionConfigOptions(sessionState: SessionState): Array<acp.SessionConfigOption> {
         const currentModelId = ModelId.fromString(sessionState.currentModelId);
         return [
@@ -703,7 +726,7 @@ export class CodexAcpServer implements acp.Agent {
             .join("-");
     }
 
-    private createModelState(availableModels: Model[], selectedModelId: string): SessionModelState {
+    private createModelState(availableModels: Model[], selectedModelId: string): LegacySessionModelState {
         const allowedModels = availableModels
             .flatMap((model) =>
                 model.supportedReasoningEfforts.map((effort) => ({
@@ -722,7 +745,7 @@ export class CodexAcpServer implements acp.Agent {
         request: acp.LoadSessionRequest
     ): Promise<{
         sessionId: SessionId;
-        modelState: SessionModelState;
+        modelState: LegacySessionModelState;
         modeState: SessionModeState;
         thread: Thread;
     }> {
@@ -797,7 +820,7 @@ export class CodexAcpServer implements acp.Agent {
         }
 
         await this.availableCommands.publish(sessionId);
-        const sessionModelState: SessionModelState = this.createModelState(models, currentModelId);
+        const sessionModelState: LegacySessionModelState = this.createModelState(models, currentModelId);
         const sessionModeState: SessionModeState = sessionState.agentMode.toSessionModeState();
 
         return {
diff --git a/src/__tests__/CodexACPAgent/CodexAcpClient.test.ts b/src/__tests__/CodexACPAgent/CodexAcpClient.test.ts
index 6924d739..c9e346d6 100644
--- a/src/__tests__/CodexACPAgent/CodexAcpClient.test.ts
+++ b/src/__tests__/CodexACPAgent/CodexAcpClient.test.ts
@@ -109,7 +109,7 @@ describe('ACP server test', { timeout: 40_000 }, () => {
         const authenticatedResponse = await keyFixture.getCodexAcpAgent().extMethod("authentication/status", {});
         expect(authenticatedResponse).toEqual({type: "api-key"});
 
-        await keyFixture.getCodexAcpAgent().unstable_logout({});
+        await keyFixture.getCodexAcpAgent().logout({});
         const logoutResponse = await keyFixture.getCodexAcpAgent().extMethod("authentication/status", {});
         expect(logoutResponse).toEqual({type: "unauthenticated"});
     });
@@ -210,7 +210,7 @@ describe('ACP server test', { timeout: 40_000 }, () => {
         const mockFixture = createCodexMockTestFixture();
         const codexAcpAgent = mockFixture.getCodexAcpAgent();
 
-        const logoutSpy = vi.spyOn(codexAcpAgent, "unstable_logout").mockResolvedValue();
+        const logoutSpy = vi.spyOn(codexAcpAgent, "logout").mockResolvedValue();
 
         await expect(codexAcpAgent.extMethod("authentication/logout", {})).resolves.toEqual({});
         expect(logoutSpy).toHaveBeenCalledWith({});
diff --git a/src/__tests__/CodexACPAgent/e2e/acp-e2e-session-persistence.test.ts b/src/__tests__/CodexACPAgent/e2e/acp-e2e-session-persistence.test.ts
index 037e3631..95ada735 100644
--- a/src/__tests__/CodexACPAgent/e2e/acp-e2e-session-persistence.test.ts
+++ b/src/__tests__/CodexACPAgent/e2e/acp-e2e-session-persistence.test.ts
@@ -1,4 +1,5 @@
 import {afterEach, expect, it} from "vitest";
+import {legacySetSessionModel, type LegacyLoadSessionResponse} from "../../../AcpExtensions";
 import {
     createAuthenticatedFixture,
     describeE2E,
@@ -22,7 +23,7 @@ describeE2E("E2E session persistence tests", () => {
         beforeRestartFixture = await createAuthenticatedFixture();
         const sessionId = (await beforeRestartFixture.createSession()).sessionId;
 
-        await beforeRestartFixture.connection.unstable_setSessionModel({sessionId, modelId: OTHER_TEST_MODEL_ID.toString()});
+        await legacySetSessionModel(beforeRestartFixture.connection, {sessionId, modelId: OTHER_TEST_MODEL_ID.toString()});
         const memorizedToken = "token-for-tests-123";
         await beforeRestartFixture.expectPromptText(
             sessionId,
@@ -36,7 +37,7 @@ describeE2E("E2E session persistence tests", () => {
             sessionId,
             cwd: afterRestartFixture.workspaceDir,
             mcpServers: [],
-        });
+        }) as LegacyLoadSessionResponse;
         expect(loadSessionResponse.models?.currentModelId).toBe(OTHER_TEST_MODEL_ID.toString());
 
         await afterRestartFixture.expectPromptText(
diff --git a/src/__tests__/CodexACPAgent/e2e/acp-e2e.test.ts b/src/__tests__/CodexACPAgent/e2e/acp-e2e.test.ts
index 9dc2f179..84b8ee6e 100644
--- a/src/__tests__/CodexACPAgent/e2e/acp-e2e.test.ts
+++ b/src/__tests__/CodexACPAgent/e2e/acp-e2e.test.ts
@@ -1,6 +1,7 @@
 import path from "node:path";
 import {afterEach, expect, it} from "vitest";
 import {AgentMode} from "../../../AgentMode";
+import {legacySetSessionModel} from "../../../AcpExtensions";
 import {
     createAuthenticatedFixture,
     createGatewayFixture,
@@ -49,7 +50,7 @@ describeE2E("E2E tests", () => {
         expect(models.availableModels.length).toBeGreaterThan(0);
         expect(models.currentModelId).toBe(DEFAULT_TEST_MODEL_ID.toString());
 
-        await fixture.connection.unstable_setSessionModel({
+        await legacySetSessionModel(fixture.connection, {
             sessionId: session.sessionId,
             modelId: OTHER_TEST_MODEL_ID.toString(),
         });
diff --git a/src/__tests__/CodexACPAgent/e2e/spawned-agent-fixture.ts b/src/__tests__/CodexACPAgent/e2e/spawned-agent-fixture.ts
index 7ec42d85..583f9501 100644
--- a/src/__tests__/CodexACPAgent/e2e/spawned-agent-fixture.ts
+++ b/src/__tests__/CodexACPAgent/e2e/spawned-agent-fixture.ts
@@ -7,6 +7,7 @@ import {expect, vi} from "vitest";
 import {ModelId} from "../../../ModelId";
 import {removeDirectoryWithRetry, writeCodexHomeConfig} from "../../acp-test-utils";
 import type {PermissionResponder} from "./permission-responders";
+import type {LegacyNewSessionResponse} from "../../../AcpExtensions";
 
 export const DEFAULT_TEST_MODEL_ID = ModelId.create("gpt-5.2", "none");
 export const OTHER_TEST_MODEL_ID = ModelId.create("gpt-5.3-codex", "low");
@@ -20,7 +21,7 @@ export interface TestSkill {
 export interface SpawnedAgentFixture {
     readonly connection: acp.ClientSideConnection;
     readonly workspaceDir: string;
-    createSession(mcpServers?: acp.McpServer[]): Promise<acp.NewSessionResponse>;
+    createSession(mcpServers?: acp.McpServer[]): Promise<LegacyNewSessionResponse>;
     restart(): Promise<SpawnedAgentFixture>;
     writeSkill(skill: TestSkill, rootDir?: string): void;
     setPermissionResponder(responder: PermissionResponder): void;
@@ -166,11 +167,11 @@ class SpawnedAgentFixtureImpl implements SpawnedAgentFixture {
         return this.paths.workspaceDir;
     }
 
-    async createSession(mcpServers: acp.McpServer[] = []): Promise<acp.NewSessionResponse> {
+    async createSession(mcpServers: acp.McpServer[] = []): Promise<LegacyNewSessionResponse> {
         return await this.connection.newSession({
             cwd: this.workspaceDir,
             mcpServers,
-        });
+        }) as LegacyNewSessionResponse;
     }
 
     async restart(): Promise<SpawnedAgentFixture> {
diff --git a/src/__tests__/CodexACPAgent/session-config-options.test.ts b/src/__tests__/CodexACPAgent/session-config-options.test.ts
index e01c9b31..64f4e125 100644
--- a/src/__tests__/CodexACPAgent/session-config-options.test.ts
+++ b/src/__tests__/CodexACPAgent/session-config-options.test.ts
@@ -6,6 +6,7 @@ import {
     REASONING_EFFORT_CONFIG_ID,
 } from "../../ModelConfigOption";
 import type {Model, ReasoningEffortOption} from "../../app-server/v2";
+import {LEGACY_SET_SESSION_MODEL_METHOD} from "../../AcpExtensions";
 
 const lowEffort: ReasoningEffortOption = {reasoningEffort: "low", description: "Fast"};
 const mediumEffort: ReasoningEffortOption = {reasoningEffort: "medium", description: "Balanced"};
@@ -43,7 +44,7 @@ async function createSession(currentModelId: string, availableModels: Array<Mode
     });
 
     const response = await codexAcpAgent.newSession({cwd: "/test/cwd", mcpServers: []});
-    return {codexAcpAgent, response};
+    return {codexAcpAgent, codexAcpClient, response};
 }
 
 describe("Session config options", () => {
@@ -189,6 +190,20 @@ describe("Session config options", () => {
         expect(sessionState.availableModels.map(m => m.id)).toEqual(["fast-model", "extra-model"]);
     });
 
+    it("changes the model through the legacy session/set_model extMethod", async () => {
+        const {fast, slow} = buildModels();
+        const {codexAcpAgent, codexAcpClient} = await createSession("fast-model[medium]", [fast]);
+        vi.spyOn(codexAcpClient, "fetchAvailableModels").mockResolvedValue([fast, slow]);
+
+        const response = await codexAcpAgent.extMethod(LEGACY_SET_SESSION_MODEL_METHOD, {
+            sessionId: "session-id",
+            modelId: "slow-model[medium]",
+        });
+
+        expect(response).toEqual({});
+        expect(codexAcpAgent.getSessionState("session-id").currentModelId).toBe("slow-model[medium]");
+    });
+
     it("rejects unknown model, effort, and mode values", async () => {
         const {fast} = buildModels();
         const {codexAcpAgent} = await createSession("fast-model[medium]", [fast]);
diff --git a/src/__tests__/CodexACPAgent/session-delete.test.ts b/src/__tests__/CodexACPAgent/session-delete.test.ts
index 9b551da2..4f8b5f82 100644
--- a/src/__tests__/CodexACPAgent/session-delete.test.ts
+++ b/src/__tests__/CodexACPAgent/session-delete.test.ts
@@ -21,7 +21,7 @@ describe("ACP session delete", () => {
     it("archives sessions that are not active locally", async () => {
         const fixture = createCodexMockTestFixture();
 
-        await expect(fixture.getCodexAcpAgent().unstable_deleteSession({sessionId})).resolves.toEqual({});
+        await expect(fixture.getCodexAcpAgent().deleteSession({sessionId})).resolves.toEqual({});
 
         await expect(fixture.getCodexConnectionDump([])).toMatchFileSnapshot(
             "data/session-delete-unknown-local.json"
@@ -31,7 +31,7 @@ describe("ACP session delete", () => {
     it("closes local session resources before archiving", async () => {
         const {fixture, codexAcpAgent} = await createSession();
 
-        await expect(codexAcpAgent.unstable_deleteSession({sessionId})).resolves.toEqual({});
+        await expect(codexAcpAgent.deleteSession({sessionId})).resolves.toEqual({});
 
         await expect(fixture.getCodexConnectionDump([])).toMatchFileSnapshot(
             "data/session-delete-idle.json"
@@ -45,7 +45,7 @@ describe("ACP session delete", () => {
         await codexAcpAgent.closeSession({sessionId});
         fixture.clearCodexConnectionDump();
 
-        await expect(codexAcpAgent.unstable_deleteSession({sessionId})).resolves.toEqual({});
+        await expect(codexAcpAgent.deleteSession({sessionId})).resolves.toEqual({});
 
         await expect(fixture.getCodexConnectionDump([])).toMatchFileSnapshot(
             "data/session-delete-unknown-local.json"
@@ -56,7 +56,7 @@ describe("ACP session delete", () => {
         const {fixture, codexAcpAgent} = await createSession();
         codexAcpAgent.getSessionState(sessionId).currentTurnId = "turn-id";
 
-        await expect(codexAcpAgent.unstable_deleteSession({sessionId})).resolves.toEqual({});
+        await expect(codexAcpAgent.deleteSession({sessionId})).resolves.toEqual({});
 
         await expect(fixture.getCodexConnectionDump([])).toMatchFileSnapshot(
             "data/session-delete-active-turn.json"
@@ -73,7 +73,7 @@ describe("ACP session delete", () => {
         vi.spyOn(codexAcpClient, "deleteSession").mockReturnValue(archive.promise);
         const resumeSessionSpy = vi.spyOn(codexAcpClient, "resumeSession");
 
-        const deletePromise = codexAcpAgent.unstable_deleteSession({sessionId});
+        const deletePromise = codexAcpAgent.deleteSession({sessionId});
         await vi.waitFor(() => {
             expect(codexAcpClient.deleteSession).toHaveBeenCalledWith(sessionId);
         });
@@ -95,7 +95,7 @@ describe("ACP session delete", () => {
         vi.spyOn(codexAcpClient, "deleteSession").mockReturnValue(archive.promise);
         const loadSessionSpy = vi.spyOn(codexAcpClient, "loadSession");
 
-        const deletePromise = codexAcpAgent.unstable_deleteSession({sessionId});
+        const deletePromise = codexAcpAgent.deleteSession({sessionId});
         await vi.waitFor(() => {
             expect(codexAcpClient.deleteSession).toHaveBeenCalledWith(sessionId);
         });