diff --git a/packages/server/src/server/agent/providers/acp-agent.test.ts b/packages/server/src/server/agent/providers/acp-agent.test.ts
index b686497b5..a5bad22f5 100644
--- a/packages/server/src/server/agent/providers/acp-agent.test.ts
+++ b/packages/server/src/server/agent/providers/acp-agent.test.ts
@@ -415,10 +415,39 @@ describe("transformPiModels", () => {
 });
 
 describe("ACPAgentSession slash commands", () => {
-  test("caches ACP available commands for listCommands", async () => {
+  test("returns immediately for ACP sessions that do not wait for async command discovery", async () => {
     const session = createSession();
 
-    expect(await session.listCommands()).toEqual([]);
+    await expect(session.listCommands()).resolves.toEqual([]);
+  });
+
+  test("waits for async available_commands_update when enabled", async () => {
+    const session = new ACPAgentSession(
+      {
+        provider: "pi",
+        cwd: "/tmp/paseo-acp-test",
+      },
+      {
+        provider: "pi",
+        logger: createTestLogger(),
+        defaultCommand: ["pi-acp"],
+        defaultModes: [],
+        modelTransformer: transformPiModels,
+        sessionResponseTransformer: transformPiSessionResponse,
+        capabilities: {
+          supportsStreaming: true,
+          supportsSessionPersistence: true,
+          supportsDynamicModes: true,
+          supportsMcpServers: false,
+          supportsReasoningStream: true,
+          supportsToolInvocations: true,
+        },
+        waitForInitialCommands: true,
+        initialCommandsWaitTimeoutMs: 1500,
+      },
+    );
+
+    const listCommandsPromise = session.listCommands();
 
     (session as any).translateSessionUpdate({
       sessionUpdate: "available_commands_update",
@@ -434,6 +463,19 @@ describe("ACPAgentSession slash commands", () => {
       ],
     });
 
+    expect(await listCommandsPromise).toEqual([
+      {
+        name: "research_codebase",
+        description: "Search the workspace for relevant files",
+        argumentHint: "",
+      },
+      {
+        name: "create_plan",
+        description: "Draft a plan for the requested work",
+        argumentHint: "",
+      },
+    ]);
+
     expect(await session.listCommands()).toEqual([
       {
         name: "research_codebase",
diff --git a/packages/server/src/server/agent/providers/acp-agent.ts b/packages/server/src/server/agent/providers/acp-agent.ts
index f0a90b0ac..83802b2b3 100644
--- a/packages/server/src/server/agent/providers/acp-agent.ts
+++ b/packages/server/src/server/agent/providers/acp-agent.ts
@@ -125,6 +125,8 @@ type ACPAgentClientOptions = {
     thinkingOptionId: string,
   ) => Promise<void>;
   capabilities?: AgentCapabilityFlags;
+  waitForInitialCommands?: boolean;
+  initialCommandsWaitTimeoutMs?: number;
 };
 
 type ACPAgentSessionOptions = {
@@ -144,6 +146,8 @@ type ACPAgentSessionOptions = {
   capabilities: AgentCapabilityFlags;
   handle?: AgentPersistenceHandle;
   launchEnv?: Record<string, string>;
+  waitForInitialCommands?: boolean;
+  initialCommandsWaitTimeoutMs?: number;
 };
 
 type SpawnedACPProcess = {
@@ -302,6 +306,8 @@ export class ACPAgentClient implements AgentClient {
     sessionId: string,
     thinkingOptionId: string,
   ) => Promise<void>;
+  private readonly waitForInitialCommands: boolean;
+  private readonly initialCommandsWaitTimeoutMs: number;
 
   constructor(options: ACPAgentClientOptions) {
     this.provider = options.provider;
@@ -314,6 +320,8 @@ export class ACPAgentClient implements AgentClient {
     this.sessionResponseTransformer = options.sessionResponseTransformer;
     this.toolSnapshotTransformer = options.toolSnapshotTransformer;
     this.thinkingOptionWriter = options.thinkingOptionWriter;
+    this.waitForInitialCommands = options.waitForInitialCommands ?? false;
+    this.initialCommandsWaitTimeoutMs = options.initialCommandsWaitTimeoutMs ?? 1500;
   }
 
   async createSession(
@@ -335,6 +343,8 @@ export class ACPAgentClient implements AgentClient {
         thinkingOptionWriter: this.thinkingOptionWriter,
         capabilities: this.capabilities,
         launchEnv: launchContext?.env,
+        waitForInitialCommands: this.waitForInitialCommands,
+        initialCommandsWaitTimeoutMs: this.initialCommandsWaitTimeoutMs,
       },
     );
     await session.initializeNewSession();
@@ -375,6 +385,8 @@ export class ACPAgentClient implements AgentClient {
       capabilities: this.capabilities,
       handle,
       launchEnv: launchContext?.env,
+      waitForInitialCommands: this.waitForInitialCommands,
+      initialCommandsWaitTimeoutMs: this.initialCommandsWaitTimeoutMs,
     });
     await session.initializeResumedSession();
     return session;
@@ -617,6 +629,10 @@ export class ACPAgentSession implements AgentSession, ACPClient {
   private lastActivityAt: string | null = null;
   private configOptions: SessionConfigOption[] = [];
   private cachedCommands: AgentSlashCommand[] = [];
+  private commandsReadyDeferred: { promise: Promise<void>; resolve: () => void } | null = null;
+  private commandsReadySettled = false;
+  private waitForInitialCommands: boolean;
+  private initialCommandsWaitTimeoutMs: number;
   private currentTurnUsage: AgentUsage | undefined;
   private activeForegroundTurnId: string | null = null;
   private closed = false;
@@ -645,6 +661,8 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     this.currentModel = config.model ?? null;
     this.thinkingOptionId = config.thinkingOptionId ?? null;
     this.currentTitle = config.title ?? null;
+    this.waitForInitialCommands = options.waitForInitialCommands ?? false;
+    this.initialCommandsWaitTimeoutMs = options.initialCommandsWaitTimeoutMs ?? 1500;
   }
 
   get id(): string | null {
@@ -876,7 +894,59 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     return this.currentMode;
   }
 
+  private ensureCommandsReadyDeferred(): void {
+    if (this.commandsReadyDeferred || this.commandsReadySettled || this.cachedCommands.length > 0) {
+      return;
+    }
+
+    let resolve!: () => void;
+    const promise = new Promise<void>((r) => {
+      resolve = r;
+    });
+    this.commandsReadyDeferred = { promise, resolve };
+  }
+
+  private settleCommandsReady(): void {
+    if (this.commandsReadySettled) {
+      return;
+    }
+    this.commandsReadySettled = true;
+    this.commandsReadyDeferred?.resolve();
+    this.commandsReadyDeferred = null;
+  }
+
+  private async waitForCommandsReady(): Promise<void> {
+    const deferred = this.commandsReadyDeferred;
+    if (!deferred) {
+      return;
+    }
+
+    let timer: ReturnType<typeof setTimeout> | null = null;
+    try {
+      await Promise.race([
+        deferred.promise,
+        new Promise<void>((resolve) => {
+          timer = setTimeout(resolve, this.initialCommandsWaitTimeoutMs);
+        }),
+      ]);
+    } finally {
+      if (timer) {
+        clearTimeout(timer);
+      }
+    }
+  }
+
   async listCommands(): Promise<AgentSlashCommand[]> {
+    if (this.cachedCommands.length > 0) {
+      return this.cachedCommands;
+    }
+    if (!this.waitForInitialCommands || this.closed) {
+      return this.cachedCommands;
+    }
+
+    this.ensureCommandsReadyDeferred();
+    await this.waitForCommandsReady();
+    this.settleCommandsReady();
     return this.cachedCommands;
   }
 
@@ -1046,6 +1116,8 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     }
     this.closed = true;
 
+    this.settleCommandsReady();
+
     for (const pending of this.pendingPermissions.values()) {
       pending.resolve({ outcome: { outcome: "cancelled" } });
     }
@@ -1392,6 +1464,7 @@ export class ACPAgentSession implements AgentSession, ACPClient {
           description: command.description,
           argumentHint: "",
         }));
+        this.settleCommandsReady();
         return [];
       default:
         return [];
diff --git a/packages/server/src/server/agent/providers/pi-acp-agent.ts b/packages/server/src/server/agent/providers/pi-acp-agent.ts
index 94d24f4d2..7d3d9588d 100644
--- a/packages/server/src/server/agent/providers/pi-acp-agent.ts
+++ b/packages/server/src/server/agent/providers/pi-acp-agent.ts
@@ -298,6 +298,8 @@ export class PiACPAgentClient extends ACPAgentClient {
         await connection.setSessionMode({ sessionId, modeId: thinkingOptionId });
       },
       capabilities: PI_CAPABILITIES,
+      waitForInitialCommands: true,
+      initialCommandsWaitTimeoutMs: 1500,
     });
   }