[SamChou19815]

What changed / motivation ?

Flow's experimental.require_dictionary_key_label option requires every dictionary key to be labeled, as TypeScript does:

type T = { [string]: number }; // error
type T = { [key: string]: number }; // ok

This labels the 44 unlabeled keys in @stylexjs/stylex's Flow types (StyleXTypes.js, StyleXUtils.js and stylex.js) as key, the label StyleXTypes.d.ts already uses. Labels don't affect type checking. Prettier rewrapped the lines that grew past the print width.

Meta's internal copy of these files is turning the option on, so the labels need to land here too, or the next upgrade drops them.

Linked PR/Issues

None.

Additional Context

• flow full-check with Flow 0.338.0, using a copy of .flowconfig updated for 0.338 with the option turned on: the 44 missing-dictionary-key-label errors in these three files are gone, and no other errors change.
• prettier --check (3.5.3 with prettier-plugin-hermes-parser 0.36.1, the versions in yarn.lock) passes on the changed files.

Pre-flight checklist

• I have read the contributing guidelines
  Contribution Guidelines
• Performed a self-review of my code

[vercel]

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[Copilot]

🟢 Approval recommended

The Flow dictionary-key labeling changes have no active review issues.

No open issues 🎉

What changed in this PR

Updates @stylexjs/stylex Flow types to support experimental.require_dictionary_key_label, keeping the public source compatible with the stricter internal configuration without changing type-checking semantics or runtime behavior.

Changes:

• Labels 44 dictionary keys as key, matching the existing TypeScript convention.
• Rewraps affected type declarations to preserve formatting.

File	Description
packages/​@stylexjs/​stylex/​src/​types/​StyleXUtils.js	Labels the dictionary key in ValueWithDefault.
packages/​@stylexjs/​stylex/​src/​types/​StyleXTypes.js	Labels dictionary keys throughout shared Flow types and constraints.
packages/​@stylexjs/​stylex/​src/​stylex.js	Labels dictionary keys in API annotations and the IStyleX interface.

_{Review effort: Balanced}