feat (ai): replace maxSteps with continueUntil (streamText) (#6393)

## Background

The `maxSteps` parameter is not flexible enough for use cases that
require more fine grained controlled over when the steps loop should
end, e.g. when token consumption is exhausted or when a specific tool
has been called.

## Summary

Replace `maxSteps` in `streamText` with `continueUntil`, which takes a
more flexible `StopCondition`.

## Future Work

- Array support for `continueUntil`

Author: lgrammel

.changeset/unlucky-bikes-fry.md

@@ -0,0 +1,5 @@
+---
+'ai': major
+---
+
+feat (ai): replace maxSteps with continueUntil (streamText)

examples/ai-core/src/stream-text/amazon-bedrock-chatbot.ts

@@ -1,5 +1,5 @@
 import { bedrock } from '@ai-sdk/amazon-bedrock';
-import { ModelMessage, streamText, tool } from 'ai';
+import { maxSteps, ModelMessage, streamText, tool } from 'ai';
 import 'dotenv/config';
 import * as readline from 'node:readline/promises';
 import { z } from 'zod';
@@ -33,7 +33,7 @@ async function main() {
           }),
         }),
       },
-      maxSteps: 5,
+      continueUntil: maxSteps(5),
       messages,
     });
 

examples/ai-core/src/stream-text/amazon-bedrock-fullstream.ts

@@ -1,5 +1,5 @@
 import { bedrock } from '@ai-sdk/amazon-bedrock';
-import { streamText, ToolCallPart, ToolResultPart } from 'ai';
+import { maxSteps, streamText, ToolCallPart, ToolResultPart } from 'ai';
 import 'dotenv/config';
 import { z } from 'zod';
 import { weatherTool } from '../tools/weather-tool';
@@ -14,7 +14,7 @@ async function main() {
       },
     },
     prompt: 'What is the weather in San Francisco?',
-    maxSteps: 5,
+    continueUntil: maxSteps(5),
   });
 
   let enteredReasoning = false;

examples/ai-core/src/stream-text/amazon-bedrock-reasoning-chatbot.ts

@@ -1,5 +1,5 @@
 import { createAmazonBedrock } from '@ai-sdk/amazon-bedrock';
-import { ModelMessage, streamText, tool } from 'ai';
+import { maxSteps, ModelMessage, streamText, tool } from 'ai';
 import 'dotenv/config';
 import * as readline from 'node:readline/promises';
 import { z } from 'zod';
@@ -46,7 +46,7 @@ async function main() {
           }),
         }),
       },
-      maxSteps: 5,
+      continueUntil: maxSteps(5),
       maxRetries: 0,
       providerOptions: {
         bedrock: {

examples/ai-core/src/stream-text/amazon-bedrock-reasoning-fullstream.ts

@@ -1,5 +1,5 @@
 import { bedrock } from '@ai-sdk/amazon-bedrock';
-import { streamText, ToolCallPart, ToolResultPart } from 'ai';
+import { maxSteps, streamText, ToolCallPart, ToolResultPart } from 'ai';
 import 'dotenv/config';
 import { weatherTool } from '../tools/weather-tool';
 
@@ -15,7 +15,7 @@ async function main() {
         reasoningConfig: { type: 'enabled', budgetTokens: 1024 },
       },
     },
-    maxSteps: 5,
+    continueUntil: maxSteps(5),
     maxRetries: 5,
   });
 

examples/ai-core/src/stream-text/amazon-bedrock-reasoning.ts

@@ -1,5 +1,5 @@
 import { bedrock } from '@ai-sdk/amazon-bedrock';
-import { streamText } from 'ai';
+import { maxSteps, streamText } from 'ai';
 import 'dotenv/config';
 
 async function main() {
@@ -16,7 +16,7 @@ async function main() {
       },
     },
     maxRetries: 0,
-    maxSteps: 5,
+    continueUntil: maxSteps(5),
   });
 
   for await (const part of result.fullStream) {

examples/ai-core/src/stream-text/anthropic-chatbot.ts

@@ -1,5 +1,5 @@
 import { anthropic } from '@ai-sdk/anthropic';
-import { ModelMessage, streamText, tool } from 'ai';
+import { maxSteps, ModelMessage, streamText, tool } from 'ai';
 import 'dotenv/config';
 import * as readline from 'node:readline/promises';
 import { z } from 'zod';
@@ -33,7 +33,7 @@ async function main() {
           }),
         }),
       },
-      maxSteps: 5,
+      continueUntil: maxSteps(5),
       messages,
     });
 

examples/ai-core/src/stream-text/anthropic-reasoning-chatbot.ts

@@ -1,5 +1,5 @@
 import { AnthropicProviderOptions, createAnthropic } from '@ai-sdk/anthropic';
-import { ModelMessage, streamText, tool } from 'ai';
+import { maxSteps, ModelMessage, streamText, tool } from 'ai';
 import 'dotenv/config';
 import * as readline from 'node:readline/promises';
 import { z } from 'zod';
@@ -46,7 +46,7 @@ async function main() {
           }),
         }),
       },
-      maxSteps: 5,
+      continueUntil: maxSteps(5),
       maxRetries: 0,
       providerOptions: {
         anthropic: {

examples/ai-core/src/stream-text/anthropic-reasoning-fullstream.ts

@@ -1,6 +1,7 @@
 import { anthropic } from '@ai-sdk/anthropic';
 import {
   extractReasoningMiddleware,
+  maxSteps,
   streamText,
   ToolCallPart,
   ToolResultPart,
@@ -28,7 +29,7 @@ async function main() {
       weather: weatherTool,
     },
     prompt: 'What is the weather in San Francisco?',
-    maxSteps: 5,
+    continueUntil: maxSteps(5),
   });
 
   let enteredReasoning = false;

examples/ai-core/src/stream-text/cohere-chatbot.ts

@@ -1,5 +1,5 @@
 import { cohere } from '@ai-sdk/cohere';
-import { ModelMessage, streamText, tool } from 'ai';
+import { maxSteps, ModelMessage, streamText, tool } from 'ai';
 import 'dotenv/config';
 import * as readline from 'node:readline/promises';
 import { z } from 'zod';
@@ -31,7 +31,7 @@ async function main() {
           }),
         }),
       },
-      maxSteps: 5,
+      continueUntil: maxSteps(5),
       messages,
     });