Migrate pycon styleguide into the monorepo

[marcoacierno]

What

ToDo

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Project	Deployment	Actions	Updated (UTC)
pycon	Ready	Preview	Apr 22, 2026 8:41pm

[claude]

This PR migrates the @python-italia/pycon-styleguide npm package into the monorepo as frontend-styleguide/, adding ~34,500 lines. It is marked as a draft and is not yet wired up to replace the external dependency.

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Blocking Issues

No pnpm workspace integration
frontend/package.json still references "@python-italia/pycon-styleguide": "0.1.210" (external npm). Without a pnpm-workspace.yaml at the repo root and a workspace:* reference in frontend/package.json, the migrated code has no effect — the frontend will continue fetching from npm.

JSX attribute errors in ticket/wrapper.tsx
Lines use HTML attribute syntax instead of JSX equivalents (stroke-width → strokeWidth, fill-opacity → fillOpacity, fill-rule → fillRule, etc.). With strict mode enabled in tsconfig.json this is a TypeScript compilation failure. There are also thousands of lines of commented-out SVG code in this file that should be cleaned up.

Separate pnpm-lock.yaml not integrated
frontend-styleguide/pnpm-lock.yaml is a standalone lockfile. A pnpm monorepo should use a single root lockfile; the separate file means pnpm install at the root won't install these dependencies and CI pipelines need explicit updates.

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Significant Issues

Severely outdated toolchain vs. rest of monorepo

• Storybook 6.5 (EOL, current is 8.x — has known security vulnerabilities)
• Rollup 2.79 (current: 4.x; plugin ecosystem is incompatible)
• Jest 27 / ts-jest 27 (current: 29)
• TypeScript 4.9.5 vs. ^5.5.4 in frontend/
• @types/react: "^17.0.80" vs. React 19 in frontend/

This creates a two-tier maintenance burden and may cause type conflicts when the internal package is consumed.

No unit tests
Jest + ts-jest infrastructure exists but zero test files (*.test.tsx) are included. The schedule logic, countdown math, filter state machine, and carousel pagination all have non-trivial branching with no coverage.

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Bugs

Countdown component is non-reactive (countdown/countdown.tsx): timeLeftUntil(deadline) is called at render time with no setInterval/useEffect. The displayed time will never update.

DayHeader crashes on empty events (schedule/schedule.tsx): day.events[0].start is accessed without a guard — throws if a day has no scheduled events.

Hardcoded 3-day schedule (schedule/schedule.tsx line ~32080): const days = [program.days[0], program.days[1], program.days[2]] silently drops any day beyond day 3.

countFilters logic bug (filter-bar/filter-bar.tsx): Object.keys(Object.values(...).filter(...)) returns array indices, not a meaningful count. Should be Object.values(appliedFilters).filter((v) => v.length).length.

onReset inverted behavior (filter-bar/filter-bar.tsx): When isDirty=true (user made changes), Reset reverts to previously applied filters instead of clearing. When isDirty=false, it clears everything. The branches are backwards from user expectations.

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Performance

O(n²) schedule slot lookup (schedule/schedule.tsx): slots.find(...) runs inside day.events.map(). For large schedules, use a Map keyed by slot key for O(1) lookup.

Intl.DateTimeFormat created on every render (days-selector/days-selector.tsx): Expensive Intl object instantiation should be wrapped in useMemo.

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Minor

Biome config inconsistency: frontend-styleguide/biome.json disables rules (useExhaustiveDependencies, noNonNullAssertion, noExplicitAny, noArrayIndexKey, etc.) that the root config does not. The pre-commit hook runs from the repo root and may apply the wrong config to this directory.

Version decision needed: package.json has version: "0.1.210" with prepublishOnly script and main/module/types fields suggesting continued npm publishing. The PR should clarify whether this package will still be published to npm from the monorepo, or consumed only internally via workspace.