Fix output.header config not applied to bundled client files

[Copilot]

• Identify the bug: replaceImports in generate/client.ts used a hardcoded header instead of the configured output.header for bundled client files (when using bundle: true with @hey-api/client-* plugins)
• Add outputHeaderToPrefix helper function to convert OutputHeader to a string prefix
• Update replaceImports to accept and use the configured header parameter (without hardcoded fallback — default flows from getOutput)
• Update generateClientBundle to accept header: OutputHeader and pass it to replaceImports
• Update generate/output.ts to pass config.output.header to generateClientBundle
• Add 6 tests for outputHeaderToPrefix logic in openapi-ts
• Remove hardcoded fallback in openapi-ts/generate/client.ts — fully depend on output.header value from config
• Apply the same outputHeaderToPrefix + header parameter pattern to openapi-python/generate/client.ts
• Update openapi-python/generate/output.ts to pass config.output.header to generateClientBundle
• Add 6 tests for outputHeaderToPrefix logic in openapi-python
• Fix typecheck error: Array.isArray() doesn't narrow away ReadonlyArray<string> in the false branch; use typeof header === 'string' instead for proper type narrowing
• All 590 tests pass; typecheck clean for both packages

Original prompt

---

This section details on the original issue you should resolve

<issue_title>output header does not seem to follow openapi-ts.config</issue_title>
<issue_description>### Description

Trying to add @ts-nocheck to the file header of each generated file, it doesn't seem to work. Below is my config

`import { defineConfig } from "@hey-api/openapi-ts";

export default defineConfig({
input: "./openapi.json",
output: {
header: [
"// This file is auto-generated by @hey-api/openapi-ts",
"// @ts-nocheck",
],
path: "src/references2",
},
plugins: [
"@hey-api/client-axios",
"@hey-api/schemas",
{
dates: true,
name: "@hey-api/transformers",
},
{
enums: "javascript",
name: "@hey-api/typescript",
},
{
name: "@hey-api/sdk",
transformer: true,
},
],
parser: {
transforms: {
enums: true,
},
}
});
`

Reproducible example or configuration

https://stackblitz.com/edit/hey-api-client-fetch-example

OpenAPI specification (optional)

No response

System information (optional)

No response</issue_description>

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

@mrlubos Please add a reproducible example! @mrlubos @SukkaW That sounds about right, will investigate

• Fixes output header does not seem to follow openapi-ts.config #3241

---

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Project	Deployment	Actions	Updated (UTC)
hey-api-docs	Ready	Preview, Comment	Feb 23, 2026 7:12pm

[changeset-bot]

🦋 Changeset detected

Latest commit: c66d565

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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[mrlubos]

@copilot remove the hard-coded default value altogether and fully depend on the output.header value flowing from the configuration. Add the same functionality to openapi-python if not already present.

[Copilot]

@copilot remove the hard-coded default value altogether and fully depend on the output.header value flowing from the configuration. Add the same functionality to openapi-python if not already present.

Done in 077adc6. Removed the hardcoded fallback from replaceImports in openapi-ts — it now uses header ?? '' so the default flows entirely from output.header config (which defaults to '// This file is auto-generated by @hey-api/openapi-ts' in getOutput). Applied the same outputHeaderToPrefix + header parameter pattern to openapi-python/generate/client.ts and openapi-python/generate/output.ts.

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[mrlubos]

@copilot Typecheck fails, can't use split on readonly array

[Copilot]

@copilot Typecheck fails, can't use split on readonly array

Fixed in c66d565. Array.isArray() has the signature (arg: any) => arg is any[] and doesn't narrow away ReadonlyArray<string> in the false branch, so TypeScript still saw string | ReadonlyArray<string> where .split() was called. Changed to typeof header === 'string' which correctly narrows to string / ReadonlyArray<string> in both branches.

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commit: c66d565

[codecov]

Codecov Report

❌ Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 40.09%. Comparing base (2faab85) to head (c66d565).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/openapi-ts/src/generate/client.ts	0.00%	6 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3438      +/-   ##
==========================================
- Coverage   40.11%   40.09%   -0.02%     
==========================================
  Files         476      476              
  Lines       17459    17467       +8     
  Branches     5287     5293       +6     
==========================================
  Hits         7004     7004              
- Misses       8414     8418       +4     
- Partials     2041     2045       +4     

Flag	Coverage Δ
unittests	40.09% <0.00%> (-0.02%)	⬇️

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