Remove unsafe type assertions from emoji, selection, and sound utilities

[KJ21-ENG]

Explanation of Change

Removes 12 unsafe type assertions from emoji indexing, selection serialization, and native sound loading while preserving existing behavior. EmojiTrie now uses its concrete generic and discriminated emoji shapes, SelectionScraper transforms concrete domhandler nodes while maintaining parent and sibling links, and native sound assets use typed static imports. Focused tests pin ordinary HTML, MathML relationships, and SVG foreignObject serialization.

Fixed Issues

$ #94739
PROPOSAL: #94739 (comment)

Count change

Current baseline source:

• config/eslint/eslint.seatbelt.tsv at base e69182c5379d82f41b6c9d6b7c7237d2c1cb0dd1.

Before:

• src/libs/EmojiTrie.ts: 4 violations
• src/libs/SelectionScraper/index.ts: 4 violations
• src/libs/Sound/index.native.ts: 4 violations

After:

• src/libs/EmojiTrie.ts: 0 violations
• src/libs/SelectionScraper/index.ts: 0 violations
• src/libs/Sound/index.native.ts: 0 violations

Net reduction:

• 12 fewer unsafe type assertion violations.

TSV evidence:

• The verifier restored config/eslint/eslint.seatbelt.tsv byte-for-byte after confirming zero cleanup findings in every target.

Tests

1. Focused formatter and ESLint passed for all five changed files.
2. Focused Jest passed for tests/unit/SelectionScraperTest.ts, covering ordinary HTML transformation, coherent MathML parent/sibling relationships, and pinned SVG foreignObject serialization.
3. The verifier-owned focused typecheck produced no authorized-path diagnostic; its only diagnostic was in unrelated src/components/AddressSearch/index.tsx.
4. git diff --check, changed-path proof, cleanup counts, and generated-TSV restoration passed.
5. Independent scope, type-safety, and regression reviews were clean on the final diff.
6. Exact-head Fork CI run 32134600292 passed typecheck, lint, format, React Compiler, and Jest at signed commit 725c368887968221c812d1ffbf610d47ee13eff2.

N/A: this is a behavior-preserving type-safety cleanup with no standalone manual application flow or JS-console behavior to exercise.

Offline tests

N/A: this cleanup does not change networking or offline behavior.

QA Steps

N/A: existing emoji indexing, selection serialization, and sound-asset behavior are preserved and covered by focused verification, regression tests, independent reviews, and exact-head CI.

PR Author Checklist

N/A rationale: manual platform, high-traffic-account, screenshots, assets, CSS, UI, copy, deeplink, Storybook, messaging, feature/bug-flow, and post-review-main-merge checks do not apply because this PR is a behavior-preserving type-safety cleanup and has not merged main after review. Selection serialization, emoji indexing, native sound loading, and affected consumers were examined during planning, focused tests, verification, and independent review. Every item below was considered against that scope.

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
• I followed proper code patterns (see Reviewing the code)
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I followed the guidelines as stated in the Review Guidelines
• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• If a new CSS style is added I verified that:
  • A similar style doesn't already exist
  • The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(theme.componentBG))
• If new assets were added or existing ones were modified, I verified that:
  • The assets are optimized and compressed (for SVG files, run npm run compress-svg)
  • The assets load correctly across all supported platforms.
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
• If the PR modifies a component or page that can be accessed by a direct deeplink, I verified that the code functions as expected when the deeplink is used - from a logged in and logged out account.
• If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
  • I verified that all the inputs inside a form are aligned with each other.
  • I added Design label and/or tagged @Expensify/design so the design team can review the changes.
• I added unit tests for any new feature or bug fix in this PR to help automatically prevent regressions in this user flow.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.

Screenshots/Videos

N/A: no UI behavior changed.

Changed files (5)

• src/libs/EmojiTrie.ts
• src/libs/SelectionScraper/index.ts
• src/libs/Sound/index.native.ts
• src/types/global.d.ts (reserved support path)
• tests/unit/SelectionScraperTest.ts (reserved support path)

[codecov]

Codecov Report

✅ Changes either increased or maintained existing code coverage, great job!

Files with missing lines	Coverage Δ
src/libs/Sound/index.native.ts	64.70% <ø> (ø)
src/libs/EmojiTrie.ts	96.00% <80.00%> (ø)
src/libs/SelectionScraper/index.ts	84.14% <90.24%> (+84.14%)	⬆️
... and 74 files with indirect coverage changes