fix(sdk): clear stale system-prompt cache options on prompt.set

A later chat.prompt.set() with no options left the previous prompt's providerOptions in locals, so toStreamTextOptions() could still cache a prompt that did not opt in. Always overwrite the slot. Also replaces fixed sleeps in the prompt-caching test with a bounded condition wait.

Author: ericallam

packages/trigger-sdk/src/v3/ai.ts

@@ -3416,7 +3416,7 @@ const chatPromptKey = locals.create<ChatPromptValue>("chat.prompt");
  * the system block. Stored separately so it works for both the `ResolvedPrompt`
  * and plain-string forms without mutating the prompt object.
  */
-const chatPromptProviderOptionsKey = locals.create<ProviderMetadata>(
+const chatPromptProviderOptionsKey = locals.create<ProviderMetadata | undefined>(
   "chat.prompt.providerOptions"
 );
 
@@ -3460,9 +3460,9 @@ function setChatPrompt(resolved: ResolvedPrompt | string, options?: SetChatPromp
     locals.set(chatPromptKey, resolved);
   }
 
-  if (options?.providerOptions) {
-    locals.set(chatPromptProviderOptionsKey, options.providerOptions);
-  }
+  // Always overwrite the slot (even with undefined) so a later prompt.set with
+  // no options clears a previous prompt's cache opt-in rather than leaking it.
+  locals.set(chatPromptProviderOptionsKey, options?.providerOptions);
 }
 
 /**

packages/trigger-sdk/test/promptCaching.test.ts

@@ -44,6 +44,17 @@ function makeModel(capture: Captured) {
   });
 }
 
+/** Poll until the mock model captures the system message (bounded), instead of a fixed sleep. */
+async function waitForSystemCaptured(capture: Captured, timeoutMs = 1000, intervalMs = 5) {
+  const startedAt = Date.now();
+  while (!capture.system) {
+    if (Date.now() - startedAt > timeoutMs) {
+      throw new Error("Timed out waiting for system message capture");
+    }
+    await new Promise((r) => setTimeout(r, intervalMs));
+  }
+}
+
 const SYSTEM = "You are a helpful assistant for tests.";
 
 describe("chat prompt caching — system providerOptions", () => {
@@ -63,7 +74,7 @@ describe("chat prompt caching — system providerOptions", () => {
     const harness = mockChatAgent(agent, { chatId: "pc-default" });
     try {
       await harness.sendMessage(userMessage("hi"));
-      await new Promise((r) => setTimeout(r, 20));
+      await waitForSystemCaptured(cap);
       expect(cap.system?.content).toContain("helpful assistant");
       expect(cap.system?.providerOptions).toBeUndefined();
     } finally {
@@ -92,7 +103,7 @@ describe("chat prompt caching — system providerOptions", () => {
     const harness = mockChatAgent(agent, { chatId: "pc-sugar" });
     try {
       await harness.sendMessage(userMessage("hi"));
-      await new Promise((r) => setTimeout(r, 20));
+      await waitForSystemCaptured(cap);
       expect(cap.system?.content).toContain("helpful assistant");
       expect(cap.system?.providerOptions?.anthropic?.cacheControl).toEqual({ type: "ephemeral" });
     } finally {
@@ -123,7 +134,7 @@ describe("chat prompt caching — system providerOptions", () => {
     const harness = mockChatAgent(agent, { chatId: "pc-explicit" });
     try {
       await harness.sendMessage(userMessage("hi"));
-      await new Promise((r) => setTimeout(r, 20));
+      await waitForSystemCaptured(cap);
       expect(cap.system?.providerOptions?.anthropic?.cacheControl).toEqual({
         type: "ephemeral",
         ttl: "1h",
@@ -151,7 +162,7 @@ describe("chat prompt caching — system providerOptions", () => {
     const harness = mockChatAgent(agent, { chatId: "pc-prompt-set" });
     try {
       await harness.sendMessage(userMessage("hi"));
-      await new Promise((r) => setTimeout(r, 20));
+      await waitForSystemCaptured(cap);
       expect(cap.system?.providerOptions?.anthropic?.cacheControl).toEqual({ type: "ephemeral" });
     } finally {
       await harness.close();
@@ -183,7 +194,7 @@ describe("chat prompt caching — system providerOptions", () => {
     const harness = mockChatAgent(agent, { chatId: "pc-precedence" });
     try {
       await harness.sendMessage(userMessage("hi"));
-      await new Promise((r) => setTimeout(r, 20));
+      await waitForSystemCaptured(cap);
       // The call-site option wins (ttl: "1h"), not the prompt-set default.
       expect(cap.system?.providerOptions?.anthropic?.cacheControl).toEqual({
         type: "ephemeral",