ToolLoopAgent: prepareCall types also omit `toolChoice`, `maxRetries`, `prepareStep`, and `repairToolCall` present at runtime

[hyamero]

Description

Follow-up to #18478: the fix in #18482 added 'reasoning' to the two prepareCall Pick lists in packages/ai/src/agent/tool-loop-agent-settings.ts, but the same mismatch exists for other settings keys. The runtime contract is unchanged: prepareCall receives { ...settingsWithoutCallbacks, ...options } where only the ten on* callbacks are stripped, and its return value is spread wholesale into the generateText/streamText call. So every non-callback settings key is present on the input and honored on the return, yet these are missing from both Pick lists:

• toolChoice: reading settings.toolChoice is TS2339 while the runtime value is there, and returning an override works (a returned toolChoice: 'none' reaches doGenerate as { type: 'none' }). Forcing or disabling tools based on call options is a core prepareCall use case.
• maxRetries: same shape; the settings value is present at runtime and generateText accepts a returned override.
• prepareStep: same; returning a per-call step configuration is a natural pattern for agents whose behavior varies per call.
• repairToolCall (and the deprecated experimental_repairToolCall): same.

Expected: these keys added to both Pick lists, as #18482 did for reasoning. Happy to open a PR.

Related, in case it should be handled in the same pass: the input type is Omit<AgentCallParameters<...>, 'onStepEnd' | 'onStepFinish'> & Pick<...>, so it still advertises abortSignal, onStart, onEnd, and the other call-level callbacks. Those are destructured out before prepareCall is invoked and can never be present; they are optional so this compiles, but e.g. reading options.abortSignal to wire up cancellation silently yields undefined forever. Widening the Omit would make the input type match the runtime in both directions.

Reproduction

import { ToolLoopAgent } from 'ai';

new ToolLoopAgent({
  model: 'openai/gpt-5.2',
  toolChoice: 'auto', // OK: the constructor accepts all four
  maxRetries: 5,
  prepareStep: () => undefined,
  repairToolCall: async () => null,
  prepareCall: settings => ({
    ...settings,
    toolChoice: settings.toolChoice, // TS2339, runtime value: 'auto'
    maxRetries: settings.maxRetries, // TS2339, runtime value: 5
    prepareStep: settings.prepareStep, // TS2339
    repairToolCall: settings.repairToolCall, // TS2339
    reasoning: settings.reasoning, // OK since #18482
  }),
});

AI SDK Version

• ai: 7.0.55 (Pick lists unchanged on current main)

[ai-sdk-factory]

Identify issue type

Identified as Bug
Confidence: High

Rationale

This is a concrete type-contract defect: the declared prepareCall parameters do not match the existing runtime inputs and behavior, causing valid property access to fail type checking and exposing unavailable fields.

Evidence

• prepareCall receives toolChoice, maxRetries, prepareStep, and repairToolCall at runtime, but its TypeScript input type omits them, causing TS2339 errors.
• Overrides for the omitted settings are reportedly accepted and honored at runtime, showing a mismatch between existing runtime behavior and declared types.
• The input type also advertises call-level fields such as abortSignal that are removed before invocation and therefore always resolve to undefined.

[ai-sdk-factory]

Bug Reproduction - AI SDK 7

Bug was reproduced.

Branch: main
PR: successful reproduction pull request

Details

• packages/ai/src/agent/tool-loop-agent-settings.ts omits toolChoice, maxRetries, prepareStep, repairToolCall, and experimental_repairToolCall from both prepareCall Pick lists.
• examples/ai-functions/src/reproduction/issue-18518-tool-loop-agent-prepare-call-types.ts reproduced input-property and return-override type errors for all five settings, although runtime assertions confirmed the settings are received and their overrides are honored.
• The reproduction also confirmed that the prepareCall input type advertises abortSignal, timeout, and eight lifecycle callback fields that are absent at runtime.
• Expected behavior is for prepareCall types to expose all supported non-callback settings and exclude call fields removed before invocation, allowing type-safe per-call tool, retry, step, repair, and cancellation configuration.

Relevant Documentation

• https://ai-sdk.dev/docs/agents/configuring-call-options
• https://ai-sdk.dev/docs/reference/ai-sdk-core/tool-loop-agent

[ai-sdk-factory]

Bugfix - AI SDK 7

Created bugfix and opened PR: #18522

Root Cause

The prepareCall input and return types used incomplete Pick lists and an insufficient Omit list. The reproduction confirmed the omitted settings were available and honored at runtime while TypeScript rejected them, and that advertised call-only fields were stripped before invocation.

Summary

Added toolChoice, maxRetries, prepareStep, repairToolCall, and experimental_repairToolCall to prepareCall input and return types; removed unavailable call-only fields from its input type; added an ai patch changeset.

Testing

Added type regression coverage for all newly exposed settings and for exclusion of fields absent at runtime.