Move shared utilities out of React component files

[joshblack]

Closes #

No linked issue.

Extracts constants and utility helpers from component files into local constants.ts, utils.ts, or hook/component modules for React Refresh compatibility.

Changelog

New

• Added local constants/utilities modules for FilteredActionList, KeybindingHint, Overlay, Timeline, Token, and UnderlineNav.
• Split useMedia into a hook module with separate MatchMedia component/context modules.

Changed

• Updated component files to consume the extracted helpers from non-component modules.

Removed

• Removed non-component helper declarations from component implementation files.

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; internal refactor with existing public import paths preserved.

Testing & Reviewing

Review moved helpers by component area; useMedia keeps the existing extensionless import surface.

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github-ui (Learn more about how to run integration tests)

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Latest commit: 5b888fc

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[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

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[Copilot]

Pull request overview

Refactors several @primer/react components and hooks to move non-component constants/helpers into local constants.ts, utils.ts, or dedicated modules to improve React Refresh compatibility while preserving existing public exports/import surfaces.

Changes:

• Extracted shared constants/utilities from component implementation files into colocated constants.ts / utils.ts modules (e.g. Overlay, Timeline, Token, UnderlineNav, FilteredActionList, KeybindingHint).
• Kept existing public exports stable by re-exporting moved symbols from the original component modules.
• Split MatchMedia/context out of useMedia.ts into separate hook modules while keeping useMedia’s import surface intact.

Show a summary per file

File	Description
packages/react/src/UnderlineNav/utils.ts	Introduces extracted getValidChildren helper.
packages/react/src/UnderlineNav/UnderlineNav.tsx	Consumes extracted helper and re-exports it to preserve public API.
packages/react/src/Token/utils.ts	Extracts isTokenInteractive helper.
packages/react/src/Token/constants.ts	Extracts token size constants/types.
packages/react/src/Token/TokenBase.tsx	Switches to extracted constants/utils and re-exports them.
packages/react/src/Timeline/constants.ts	Extracts TimelineBadgeVariants constant.
packages/react/src/Timeline/Timeline.tsx	Imports and re-exports extracted TimelineBadgeVariants.
packages/react/src/Overlay/constants.ts	Extracts heightMap/widthMap constants.
packages/react/src/Overlay/Overlay.tsx	Imports and re-exports extracted overlay dimension maps.
packages/react/src/KeybindingHint/components/utils.ts	Extracts key-chord parsing/sorting + accessible string helpers.
packages/react/src/KeybindingHint/components/Chord.tsx	Uses extracted chord utilities and re-exports accessibleChordString.
packages/react/src/KeybindingHint/components/Sequence.tsx	Uses extracted sequence accessibility helper and re-exports it.
packages/react/src/hooks/MatchMediaContext.ts	New module for MatchMediaContext and MediaQueryFeatures type.
packages/react/src/hooks/MatchMedia.tsx	New module for MatchMedia component + shallow-stabilization helper.
packages/react/src/hooks/useMedia.ts	Updated to consume extracted context and re-export MatchMedia.
packages/react/src/FilteredActionList/constants.ts	Extracts loader type class + constants.
packages/react/src/FilteredActionList/FilteredActionListLoaders.tsx	Imports and re-exports extracted loader symbols.

Copilot's findings

• Files reviewed: 17/17 changed files
• Comments generated: 1