# 053 — Move the log sort selector from Log Preview to the Timeline

## Summary

The "Sort by" control lives in the wrong component. It's currently
rendered inside `LogPreview`'s own section header
(`webapp/src/components/LogPreview.tsx:327-336`) as a `SortPicker`
(`LogPreview.tsx:68-107`, a `<select>` plus an "Fall back to ottyl_seq"
checkbox), with its `LogSortSettings` type and
`loadLogSortSettings`/`saveLogSortSettings` persistence helpers
(`LogPreview.tsx:37-66`, localStorage key `ottyl.logPreview.sort`) also
defined there. `LogTimeline.tsx` has no sort-related prop at all
(`LogTimeline.tsx:44-56`) — its header only has time-range preset buttons
and a "Clear selection" link (`LogTimeline.tsx:118-149`).

The actual sort state is owned one level up, duplicated identically in
`App.tsx`'s two top-level render modes: `FullApp`
(`App.tsx:389-394`) and `StandaloneLog` (`App.tsx:263-268`), both via
`useState<LogSortSettings>(loadLogSortSettings)` plus a
`handleSortSettingsChange` callback. Both currently pass
`sortSettings`/`onSortSettingsChange` only to `LogPreview`
(`App.tsx:361`, `App.tsx:527`), never to `LogTimeline`
(`App.tsx:237-243`, `354-360`/`520-526`). The setting already drives
`fetchLogs` (`App.tsx:319-326`, `464-471`, dependency at `App.tsx:347`,
`494`), which forwards `sortBy`/`sortMissingFallback` to
`GET /api/logs` via `fetchLogs` in `webapp/src/lib/api.ts:242-262`. The
backend already fully supports this — `src/dto.rs:86-90`'s
`sort_by`/`sort_missing_fallback` fields, validated and applied in
`src/engine.rs:1223-1281` (400 if `sort_by` isn't a declared param,
`engine.rs:1227`; missing-value fallback behavior at `engine.rs:1260-1281`).
The timeline query/DTO backing `fetchTimeline`
(`webapp/src/lib/api.ts:264-274`) has no `sort_by` field and doesn't need
one — this is a frontend-only relocation of where the control lives, not
a backend change.

## Scope

- Move `SortPicker` (and ideally the `LogSortSettings` type plus
  `loadLogSortSettings`/`saveLogSortSettings`) out of `LogPreview.tsx`
  into `LogTimeline.tsx`, rendering it in the Timeline's header
  (`LogTimeline.tsx:118-149`) alongside the existing range controls.
- Add `sortSettings`/`onSortSettingsChange` props to `LogTimeline`.
- Update both `App.tsx` render sites (`FullApp` around line 237,
  `StandaloneLog` around line 354/520) to pass `sortSettings`/
  `onSortSettingsChange` to `LogTimeline` instead of `LogPreview`.
- `LogPreview` keeps rendering the `logs` prop as already sorted by the
  parent's `fetchLogs` call — remove its own `SortPicker` usage and the
  now-unused sort-control markup from its header, but keep consuming
  `sortSettings` if it still needs read access to it (e.g. for a
  "sorted by X" label), or drop that too if not needed.
- No backend changes — `sort_by`/`sort_missing_fallback` on
  `GET /api/logs` are unaffected.

## Acceptance criteria

- The "Sort by" selector and "fall back to ottyl_seq" checkbox appear in
  the Timeline component's header, not in Log Preview's.
- Changing sort order from the Timeline's control changes the order of
  entries shown in Log Preview (same behavior as today, just relocated).
- The chosen sort setting still persists across reloads (localStorage key
  can be renamed if it moves file, but must not silently reset to
  default on the first load after this change — migrate or fall back
  gracefully).
- `make build` (webapp `tsc -b && vite build`) passes with no leftover
  unused imports/types in `LogPreview.tsx`.

## Depends on

None.