fix(types): fix the type definitions for factory models and config, a…

[liyown]

🎯 Changes

fix #407

✅ Checklist

• I have followed the steps in the Contributing guide.
• I have tested this code locally with pnpm run test:pr.

Summary by CodeRabbit

• Refactor
  • Enhanced type inference for adapter configuration to provide improved flexibility with factory parameters.

[coderabbitai]

📝 Walkthrough

Walkthrough

The extendAdapter function's type signature is refined to better infer and preserve all parameters from the underlying adapter factory. A new InferRestArgs type helper extracts trailing parameters, and the generic constraint is updated to explicitly require a model parameter as the first argument.

Changes

Cohort / File(s)	Summary
Type Signature Refinement packages/typescript/ai/src/extend-adapter.ts	Removed InferConfig type and conditional config logic. Introduced InferRestArgs to extract remaining parameters. Updated generic constraint to explicitly require (model: any, ...args) signature. Replaced explicit return type with type cast preserving all parameter inference from the factory.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A tale of types, now crystal clear,
Where factories whisper parameters near,
No more confusion, the model stands tall,
Rest args flow freely, extending it all! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The PR description is incomplete. It references issue #407 but lacks detail about what specific changes were made and their motivation, and the 'Release Impact' section is missing.	Expand the description to explain the specific type definition changes and clarify the release impact with a changeset or justification if docs-only.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix(types): fix the type definitions for factory models and config, a…' is related to the main changes (type definitions fix) but is truncated and generic with repeated 'fix'.
Linked Issues check	✅ Passed	The PR successfully addresses issue #407 by fixing type inference for factory models, enabling extendAdapter to work consistently with both createAnthropicChat and anthropicText factories.
Out of Scope Changes check	✅ Passed	All changes in extend-adapter.ts are scoped to fixing type definitions and inference, directly addressing the linked issue #407 with no extraneous modifications.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/typescript/ai/src/extend-adapter.ts`:
- Line 113: The generic constraint for InferRestArgs uses an invalid
rest-parameter type; update the constraint on TFactory from using (...args: any)
to a valid rest tuple type such as (...args: any[]) => any so TypeScript accepts
it. Locate the type alias InferRestArgs and change its constraint to TFactory
extends (...args: any[]) => any (and if other similar generic constraints exist
in the same file, apply the same tuple/array rest fix).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 01b3cf38-4277-449f-8500-e5e7a4f22123

📥 Commits

Reviewing files that changed from the base of the PR and between a8a4465 and 0ccbcdf.

📒 Files selected for processing (1)

• packages/typescript/ai/src/extend-adapter.ts

[coderabbitai]

⚠️ Potential issue | 🔴 Critical

🧩 Analysis chain

🌐 Web query:

Does TypeScript allow a rest parameter type annotation of any(e.g.,(...args: any) => any), or must it be an array/tuple type like any[]?

💡 Result:

No, TypeScript does not allow a rest parameter type annotation of any like (...args: any) => any. The type annotation for rest parameters must be an array type like any[], a specific array type such as number[], or a tuple type.

Citations:

• 1: https://www.typescriptlang.org/docs/handbook/2/functions.html
• 2: https://www.typescriptlang.org/docs/handbook/functions.html
• 3: https://www.typescriptlang.org/docs/handbook/2/functions

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🏁 Script executed:

head -n 120 packages/typescript/ai/src/extend-adapter.ts | tail -n 20

Repository: TanStack/ai

Length of output: 541

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Fix invalid rest-parameter typing in generic constraint.

Line 113 uses (...args: any), but TypeScript requires rest parameters to be array or tuple types (e.g., any[]). This will cause a TypeScript compilation error.

Suggested fix

-type InferRestArgs<TFactory extends (...args: any) => any> =
+type InferRestArgs<TFactory extends (...args: any[]) => any> =
   Parameters<TFactory> extends [any, ...infer Rest] ? Rest : []

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	type InferRestArgs<TFactory extends (...args: any) => any> =
	type InferRestArgs<TFactory extends (...args: any[]) => any> =
	Parameters<TFactory> extends [any, ...infer Rest] ? Rest : []

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@packages/typescript/ai/src/extend-adapter.ts` at line 113, The generic
constraint for InferRestArgs uses an invalid rest-parameter type; update the
constraint on TFactory from using (...args: any) to a valid rest tuple type such
as (...args: any[]) => any so TypeScript accepts it. Locate the type alias
InferRestArgs and change its constraint to TFactory extends (...args: any[]) =>
any (and if other similar generic constraints exist in the same file, apply the
same tuple/array rest fix).