[chdefrene]

Component Development

Type

• Feature
• Fix
• Hotfix (should release ASAP)
• Maintenance (deps only)

Reference to assignment

Related: equinor/fusion-core-tasks#2120 (not closed by this PR).
Supersedes equinor/fusion-web#52 following migration of the theme package. The old PR remains open because fusion-web is archived/read-only.

Description of assignment

Temporarily keep browser-native controls aligned with Fusion's light palette in the relocated @equinor/fusion-web-theme package. Isolate the policy so it can be removed when Fusion supports dark mode.

Description of Proposed Changes

• Add a standalone color-scheme: only light entry in colorVariables, inherited once by aggregate attributes; preserve all 75 existing color declarations and their order.
• Add regressions for uniqueness, fixed-snapshot compatibility/order, aggregate composition, and fresh-process DOM-free imports through the built public entry point. Build before running package tests.
• Document root CSS consumption, startup/body-overlay coverage, and the modern EDS caveat; include a patch changeset.

Importing the package does not inject CSS or mutate DOM/HTML attributes. Consumers must apply the declarations on the document root; protection starts when the stylesheet applies. This protects native controls, not modern EDS token palette selection: color-scheme does not disable prefers-color-scheme, and modern EDS consumers still need data-color-scheme="light" on html. No React provider changes or new legacy token imports.

Validation:

• bun run --cwd packages/theme test — passed, including build: 4 tests / 1 committed snapshot / 9 assertions. The original regressions failed before the implementation.
• bun run --cwd packages/theme build — passed.
• bun run check -- packages/theme — passed, 10 files.
• git diff --check — passed.
• Snapshot baseline independently verified against the original declarations at Git revision ddafd28: all 75 declarations and their order match. Mutation checks for reordered, removed, and changed declarations each failed the compatibility test as expected.
• The committed fresh-process test imports dist/index.js with throwing document/window getters — passed.
• bun /Users/christian.frene/.copilot/session-state/41fc6c0e-5564-4b54-bccb-99e10e6d1b1c/files/validate-theme-chrome.ts — passed against generated root declarations in isolated Chrome 156.0.8078.48. Initial light → dark → light and initial dark → light → dark retained light-only computed schemes and white native input/select backgrounds, including controls in a body-mounted overlay. Media-query emulation changed correctly; screenshots and JSON evidence are session artifacts. Subsequent review fixes only change tests, the test command, and documentation.

Full monorepo/Storybook and authenticated application validation were not run. Browser checks do not establish modern EDS palette selection or native select popup rendering.

Checklist

Create User Story(DevOps) or Issue(Github)

• Describe functional requirements
• Design plan/suggestion (e.g. images, link to eds design or relevant figma links, mention of eds tokens to use)
• Communication with UX (evaluate if needed)

No new UI design; use a removable CSS declaration only.

Development

• Describe the component
• Code funtional requirements
• Create stories
• Create snapshots (evaluate if needed)
• Remove unused imports and commented code
• Lint code with Biome (and follow best practises for code quality

No Storybook stories added for this declaration-only fix. A fixed legacy-output snapshot is committed; isolated native-control screenshots were inspected separately.

Create Pull Request

• Assign relevant reviewers in Github and Cromatic
• Inform colleagues of pending reviews. We use Teams for this purpose, under fusion-frontend team please tag involved reviewers in the Code review channel

GitHub rejected the requested fusion-core-code-reviewers team because it is not a repository collaborator. No permission changes were made.

Review of Pull Request

• Follow up on comments from code review and implement necessary changes (evaluate if needed)
• Review approved in github (and chromatic)

Address Copilot's fixed-baseline comment and built-entry validation concern in separate signed review-fix commit 30aac99; reply to and resolve the inline thread.

Publish Code

• Increment version number
• Merge PR
• Consider letting fusion developers know this this shiny new thing exists

Patch changeset included; release automation owns versioning.

[changeset-bot]

🦋 Changeset detected

Latest commit: 30aac99

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

This PR includes changesets to release 1 package

Name	Type
@equinor/fusion-web-theme	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Copilot]

🟡 Changes recommended

The two moderate test-validation issues must be addressed before approval.

1 open issue

• Compare color variables against a fixed compatibility fixture · New

What changed in this PR

This pull request adds a temporary light-only color scheme to @equinor/fusion-web-theme, keeping browser-native controls aligned with Fusion’s light palette while documenting integration limitations.

Changes:

• Adds color-scheme: only light to the exported color and aggregate declarations.
• Adds regression tests for declaration composition, ordering, uniqueness, and DOM-free imports.
• Documents root stylesheet usage and modern EDS limitations.
• Adds a patch changeset and package test script.

File	Summary
packages/​theme/​tests/​colors.test.ts	Adds regression coverage; two moderate issues remain because the compatibility check derives its baseline from current declarations and the fresh-process check targets the source entry rather than the published artifact.
packages/​theme/​src/​styles/​colors.ts	Adds the temporary light-only native control declaration while preserving existing variables.
packages/​theme/​README.md	Documents stylesheet application, scope, and modern EDS limitations.
packages/​theme/​package.json	Adds the package test script.
.changeset/​theme-native-light-mode.md	Records the patch release and behavior change.

_{Review effort: Lite}

[Copilot]

🟢 Approval recommended

The reviewed changes preserve existing output, add targeted regression coverage, document integration requirements, and have no unresolved blocking issues.

No open issues 🎉

1 resolved since last review

• Compare color variables against a fixed compatibility fixture

_{Review effort: Lite}