Fix: Type parameter shadowing in PluginInstance methods after bundling

[Copilot]

After v0.86, the TypeScript declaration bundler renames the class-level type parameter T to T$1, causing method-level type parameters also named T to incorrectly reference the class type parameter instead of their own scope.

// Before: method type parameter incorrectly resolves to class T$1
forEach<T extends IrTopLevelKind>(...args: [
  ...events: ReadonlyArray<T$1>,  // Wrong - should be method T
  callback: (event: WalkEvent<T$1>) => void
]): void;

// After: distinct parameter name preserves method scope
forEach<TKind extends IrTopLevelKind>(...args: [
  ...events: ReadonlyArray<TKind>,
  callback: (event: WalkEvent<TKind>) => void
]): void;

Changes

• Renamed method type parameters to avoid shadowing:
  • forEach: T → TKind
  • getPlugin, getPluginOrThrow: T → TName

Impact

Users can now use forEach without type errors:

plugin.forEach('schema', 'operation', (event) => {
  // event is now correctly typed as WalkEvent<'schema' | 'operation'>
  // instead of 'never'
});

Original prompt

---

This section details on the original issue you should resolve

<issue_title>PluginInstance.forEach is typed incorrectly after v0.86</issue_title>
<issue_description>### Description

After v0.86, PluginInstance.forEach is typed incorrectly. This is what the generated type before:

forEach<T extends IrTopLevelKind = IrTopLevelKind>(...args: [...events: ReadonlyArray<T>, callback: (event: WalkEvent<T>) => void]): 

and this is what we have now (note the T$1):

forEach<T extends IrTopLevelKind = IrTopLevelKind>(...args: [...events: ReadonlyArray<T$1>, callback: (event: WalkEvent<T$1>) => void]): 

Reproducible example or configuration

You can find the live minimal example here.

import type { DefinePlugin } from '@hey-api/openapi-ts';

type MyPluginConfig = { readonly name: 'myplugin' };
type MyConfig = DefinePlugin<MyPluginConfig>;

export const handler: MyConfig['Handler'] = ({ plugin }) => {
  plugin.forEach('schema', 'operation', (event) => {
    console.log(event);
  });
};

will produce the type checking error:

No overload matches this call.
  Argument of type '[string, string, (event: never) => void]' is not assignable to parameter of type '[...events: Types<MyPluginConfig, MyPluginConfig, never>[], callback: (event: never) => void]'.
    Type at positions 0 through 1 in source is not compatible with type at position 0 in target.
      Type 'string' is not assignable to type 'Types<MyPluginConfig, MyPluginConfig, never>'.
        Type 'string' is not assignable to type '{ config: MyPluginConfig; resolvedConfig: MyPluginConfig; }'.
  Argument of type '[string, string, (event: never) => void]' is not assignable to parameter of type '[...events: Types<MyPluginConfig, MyPluginConfig, never>[], callback: (event: never) => void, options: WalkOptions<Types<MyPluginConfig, MyPluginConfig, never>>]'.
    Type at position 0 in source is not compatible with type at position 0 in target.
      Type 'string' is not assignable to type 'Types<MyPluginConfig, MyPluginConfig, never>'.(2769)

OpenAPI specification (optional)

No response

System information (optional)

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes PluginInstance.forEach is typed incorrectly after v0.86 #2896

---

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🦋 Changeset detected

Latest commit: a625980

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@hey-api/openapi-ts	Patch

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Project	Deployment	Preview	Comments	Updated (UTC)
hey-api-docs	Ready	Preview	Comment	Oct 31, 2025 2:32am

[codecov]

Codecov Report

❌ Patch coverage is 69.23077% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 30.89%. Comparing base (cec4739) to head (a625980).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
...es/openapi-ts/src/plugins/shared/utils/instance.ts	69.23%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2897   +/-   ##
=======================================
  Coverage   30.89%   30.89%           
=======================================
  Files         488      488           
  Lines       40458    40458           
  Branches     2523     2523           
=======================================
  Hits        12501    12501           
  Misses      27922    27922           
  Partials       35       35           

Flag	Coverage Δ
unittests	30.89% <69.23%> (ø)

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commit: a625980