@remotion/renderer: Rename mimeType to contentType

[JonnyBurger]

Summary

• Renames mimeType to contentType in the return values of renderMedia() and renderStill()
• Updates tests and docs accordingly

Test plan

• Existing contentType assertions pass in render-media and render-still tests

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Project	Deployment	Actions	Updated (UTC)
bugs	Ready	Preview, Comment	Feb 20, 2026 10:41am
remotion	Ready	Preview, Comment	Feb 20, 2026 10:41am

[pullfrog]

Clean rename. The mimeType field was introduced in unreleased v4.0.426 (current version is 4.0.425), so there's no backward compatibility concern. All references in the renderer source, tests, and docs have been updated consistently. The remaining mimeType usages in the codebase (media-parser, devtools types, asset downloading) are unrelated to these return types. The internal types RenderMediaResult and RenderStillReturnValue are not exported, further limiting blast radius.

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[pullfrog]

LGTM. The rename is complete across types, implementation, tests, and docs. Since mimeType was introduced at v4.0.426 (unreleased — current version is 4.0.425), this is not a breaking change. The remaining mimeType references in the renderer (devtools-types.ts, download-and-map-assets-to-file.ts) are unrelated internal usages.

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[Copilot]

Pull request overview

This PR renames the mimeType field to contentType in the return values of renderMedia() and renderStill() functions in the @remotion/renderer package. This is a breaking API change that better aligns the naming with HTTP standards where "Content-Type" is the standard header name.

Changes:

• Updated return type definitions to use contentType instead of mimeType
• Updated all tests to destructure and assert on contentType instead of mimeType
• Updated documentation to reflect the new field name

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/renderer/src/render-still.ts	Updated RenderStillReturnValue type and return object to use contentType
packages/renderer/src/render-media.ts	Updated RenderMediaResult type and return object to use contentType
packages/renderer/src/test/render-still.test.ts	Updated test to destructure and assert on contentType
packages/it-tests/src/ssr/render-media.test.ts	Updated test to destructure and assert on contentType
packages/docs/docs/renderer/render-still.mdx	Updated documentation to reference contentType
packages/docs/docs/renderer/render-media.mdx	Updated documentation to reference contentType