Add Oxlint to frontend linting

[ejsmith]

Summary

• Merged current main at f5c07400 into the branch.
• Added Oxlint 1.73.0 as a fast syntax and correctness pass for JavaScript, TypeScript, and Svelte <script> blocks.
• Retained ESLint and eslint-plugin-svelte as the authoritative framework/template linter. eslint-plugin-oxlint disables only overlapping rules already covered by Oxlint.
• Retained Prettier plus the established Svelte and Tailwind plugins for formatting and editor integration.

Current scope

Vite 8 and the broader frontend dependency refresh have now landed independently on main, so they are no longer changes introduced by this PR. The remaining five-file diff is focused on the incremental Oxlint integration: its configuration, lint script, ESLint overlap handling, dependencies, and generated lockfile entries.

Type-aware oxlint-tsgolint and Oxfmt remain intentionally excluded while their Svelte and TypeScript integrations continue to mature.

Compatibility

• No backend, public API, persisted-data, WebSocket, or application behavior changes.
• The established Svelte, ESLint, Prettier, and VS Code workflows remain in place.
• No breaking Exceptionless contracts.

Dependency review

• Oxlint incremental ESLint migration
• Oxlint framework support

Verification

• npm ci — passed; 7 low, 0 moderate, 0 high, 0 critical audit findings
• npm run validate — Prettier, Svelte diagnostics, syntax-only Oxlint, and ESLint passed
• npm run build — Vite 8.1.5 production client and SSR build passed
• npm run test:unit -- --reporter=dot — 30 files, 332 tests passed
• npm run build-storybook — passed

[ejsmith]

@copilot update this PR now that vite 8 final is out. Update any deps to latest versions. Get the build working.

[Copilot]

@ejsmith I've opened a new pull request, #2152, to work on those changes. Once the pull request is ready, I'll request review from you.

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull request overview

This PR updates the ClientApp frontend toolchain to incorporate Oxlint/Oxfmt alongside ESLint/Prettier, and updates Vite-related dependencies/config to use newer native tooling.

Changes:

• Added Oxlint/Oxfmt configuration and wired them into npm run lint / npm run format.
• Updated ESLint flat config to integrate eslint-plugin-oxlint and avoid overlapping rules.
• Updated Vite config to run vite-plugin-oxlint and refreshed frontend dependencies (including Vite).

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Exceptionless.Web/ClientApp/vite.config.ts	Adds vite-plugin-oxlint to Vite plugins.
src/Exceptionless.Web/ClientApp/src/routes/(auth)/login/+page.svelte	Formatting changes in the password label markup.
src/Exceptionless.Web/ClientApp/src/lib/features/auth/schemas.ts	Reformats schema definition for readability.
src/Exceptionless.Web/ClientApp/package.json	Adds Oxlint/Oxfmt scripts, adjusts Prettier scope to Svelte, and updates dependencies.
src/Exceptionless.Web/ClientApp/eslint.config.js	Integrates eslint-plugin-oxlint, disables a Svelte false-positive rule, and loads Oxlint config.
src/Exceptionless.Web/ClientApp/.oxlintrc.json	New Oxlint configuration (plugins, rules, ignores).
src/Exceptionless.Web/ClientApp/.oxfmtrc.json	New Oxfmt configuration (style + EOL).
src/Exceptionless.Web/ClientApp/.npmrc	Enables legacy-peer-deps.

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[ejsmith]

@copilot can you rebase this PR

[Copilot]

@ejsmith I've opened a new pull request, #2163, to work on those changes. Once the pull request is ready, I'll request review from you.

[niemyjski]

Looks like we need to rebase this again

[Copilot]

Pull request overview

Copilot reviewed 235 out of 240 changed files in this pull request and generated 3 comments.

[niemyjski]

Follow-up feedback and thermo-nuclear audit completed at 5bb158f28395dd4be51155a20f45001f3b453c9c.

Feedback disposition

• Queried all 6 review threads, 8 submitted reviews, and 7 PR conversation comments. All six threads are already resolved and outdated; there are no open threads requiring a reply.
• Login label formatting: outdated / incorrect for the current tree. The file is identical to origin/main, and current Prettier intentionally produces the existing Svelte layout.
• Oxfmt ignore feedback: superseded by the tooling pivot. Oxfmt and .oxfmtrc.json are no longer in the effective diff; Prettier remains the formatter and Oxlint has explicit generated/vendor/output ignores.
• Admin controller catch feedback: outdated / superseded by main's Minimal API migration. The reviewed controller no longer exists, and the successor handler is unchanged by this PR.
• Global IncludeFields, stack-usage cache schema, and ExtendedEntityChanged mutability feedback: historical and outside this PR's current scope. Those files are byte-for-byte unchanged from origin/main; Add Oxlint to frontend linting #2118 neither introduces nor modifies those current-main behaviors.
• The old requests to update to final Vite 8 and get the build working are satisfied. The rebase requests are superseded by the normal merge commit a38599ac1, which contains current origin/main. Copilot redirect comments, CLA, and coverage comments are informational. The live feedback query contained no Codex-authored item.

RCA and current implementation

The long-lived PR previously contained unrelated backend/UI changes, so GitHub retains comments against a much broader historical diff. After the tooling pivot and merge-forward, the effective diff is five ClientApp tooling files only. It upgrades Vite to 8.1.5 / Rolldown, pairs it with @sveltejs/vite-plugin-svelte 7.2.0, and adds the matched Oxlint / ESLint bridge at 1.73.0. Oxlint 1.75 is newer but does not yet satisfy the repo's seven-day package maturity policy; 1.73 is the newest eligible matched pair.

The thermo-nuclear review found no structural blocker: no application source changes, no file crossing 1,000 lines, no new branching/casts/boundary leaks, no non-atomic state, and no duplicate build-time lint plugin. The focused Svelte probe proved the division of responsibility: Oxlint avoids its known Svelte false positive while ESLint still rejects a genuinely unused Svelte variable. No further code change was warranted.

Verification

• npm run validate — passed; Svelte check 0 errors / 0 warnings; Prettier, Oxlint, and ESLint passed
• npm run test:unit — 28 files / 323 tests passed
• npm run build — Vite 8.1.5 SSR + client production build passed
• npm run build-storybook — passed with Vite 8.1.5
• git diff --check — clean; worktree unchanged
• GitHub CI — version, API, client, E2E, Docker build, and CLA all green

No external blocker remains.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Exceptionless.Core	73%	66%	9587	➖
Exceptionless.AppHost	38%	40%	139	❌
Exceptionless.Insulation	37%	35%	286	❌
Exceptionless.Web	84%	67%	6935	✔
Summary	77% (22857 / 29790)	66% (10499 / 16026)	16947	✔