fix(desktop): make English number formatting deterministic

[yinkev]

What does this PR do?

Makes the Desktop's hard-coded English number and USD strings deterministic across host locales.

On native Windows with an en-DE ICU locale, the current formatters produce 5.000 and US$25, while the surrounding English copy, existing billing formatter, and tests require 5,000 and $25. This pins the three outlier formatting sites to en-US, matching the explicit contract already used by use-billing-state.ts for USD display strings.

The change is intentionally scoped to copy that is currently hard-coded English. It does not change user-locale-aware UI formatting elsewhere.

Related Issue

Fixes #71659

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• apps/desktop/src/components/assistant-ui/tool/fallback-model/format.ts
  • format the hard-coded English truncation count with en-US grouping.
• apps/desktop/src/app/session/hooks/use-prompt-actions/utils.ts
  • format usage call/token counts with stable en-US grouping.
• apps/desktop/src/app/settings/billing/billing-amounts.ts
  • use the same en-US USD contract as the existing billing-state formatter.
• focused regressions
  • assert the two English number paths pass en-US explicitly;
  • simulate a non-US default locale for the billing formatter and require $25.

How to Test

1. Install the locked JavaScript dependencies with npm ci --ignore-scripts.
2. Run the Desktop type checker:

   cd apps/desktop
   npm run typecheck

3. Run the focused locale regressions:

   npm run test:ui -- --run \
     src/components/assistant-ui/tool/fallback-model.test.ts \
     src/app/session/hooks/use-prompt-actions/utils.test.ts \
     src/app/settings/billing/billing-amounts.test.ts

   Expected: 62 passed.
4. Run ESLint on the six changed TypeScript files and git diff --check.

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass — N/A for this Desktop-only TypeScript change; focused UI tests and the complete Desktop typecheck pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS Apple Silicon, with the host-locale behavior reproduced through adversarial formatter mocks

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — N/A; no user-facing configuration or workflow changes
• I've updated cli-config.yaml.example if I added/changed config keys — N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — this removes host-locale variance across supported platforms
• I've updated tool descriptions/schemas if I changed tool behavior — N/A

Screenshots / Logs

No visual layout changes. Focused result:

Test Files  3 passed (3)
Tests       62 passed (62)

[teknium1]

Thanks for the focused cross-locale regression fix. Current main still uses host-default formatting in the three reported paths: apps/desktop/src/app/session/hooks/use-prompt-actions/utils.ts:301, apps/desktop/src/components/assistant-ui/tool/fallback-model/format.ts:58, and apps/desktop/src/app/settings/billing/billing-amounts.ts:117. Pinning these hard-coded English/USD strings to en-US matches the established billing contract in apps/desktop/src/app/settings/billing/use-billing-state.ts:825-832.

Current-main changes since the PR base affect earlier helpers in utils.ts, not the usage formatter; the patch should be straightforward to salvage.

Automated hermes-sweeper review.

[GottZ]

This was generated by AI during triage.

Summary

One PR addresses #71659. #71750 removes host-locale dependence from all three reported hard-coded English/USD formatting paths and adds focused regression coverage.

Related pull requests

• fix(desktop): make English number formatting deterministic #71750 best fix — (+53/-5) — n/a: Pins usage counts, truncation counts, and USD billing amounts to en-US, directly covering every reported failure; the keep_open review confirms that current main remains affected at those sites and that the patch is highly salvageable.

Suggested consolidation

Keep #71750 open with a salvage path: preserve its three production locale fixes and focused tests, rebasing them onto current main if necessary. This follows the keep_open review, which reports that intervening changes do not affect the usage formatter; there are no competing PRs to close as duplicates.

Complex graph

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    classDef merged fill:#dcfce7,stroke:#15803d,color:#14532d
    classDef closed fill:#e5e7eb,stroke:#6b7280,color:#1f2937
    classDef unverified fill:#f3f4f6,stroke:#9ca3af,color:#374151
    classDef best stroke-width:3px,stroke:#b45309
    classDef target stroke-width:3px,stroke:#4338ca
    I71659(["issue #71659 (open)"])
    P71750["PR #71750 (open)"]
    P71750 -->|best fix| I71659
    class I71659 open
    class P71750 open
    class P71750 best
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    click I71659 "https://github.com/NousResearch/hermes-agent/issues/71659"
    click P71750 "https://github.com/NousResearch/hermes-agent/pull/71750"

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Graph: solid arrow = fixes / best fix, dashed arrow = partial or unverified (see edge label); boxed group = PRs duplicating each other; amber border = best fix; indigo border = target; gray node = closed (state tag in the node label).

Cross-PR triage: Reviewed 1 pull request and 1 issue in this complex. Each diff was read against this issue; Assessment working set: 6 kB of PR diffs, 10 kB of issue/PR text, 2 verify verdicts. verdicts reflect diff content, not PR titles. Part of an automated triage batch.

[OutThisLife]

Superseded by #120267. The replacement fixes the reported locale-dependent test failures while preserving runtime number and currency formatting, following the test-only approach already landed in #81965. Thanks @yinkev for identifying the formatter paths and supplying regressions.