Move TimeRange types to lib/timeRange to break import cycle

CollapsibleSection.tsx and LogTimeline.tsx imported from each other
(TimeRange/TimeRangePresetId one way, sectionHeaderClassName the
other). Move the range types/helpers into a dependency-free
webapp/src/lib/timeRange.ts and repoint all importers there.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TeyhRfMYjMditek6geDRoQ

webapp/src/components/CollapsibleSection.tsx

@@ -1,5 +1,5 @@
 import { useState } from 'react'
-import type { TimeRange, TimeRangePresetId } from './LogTimeline'
+import type { TimeRange, TimeRangePresetId } from '../lib/timeRange'
 
 /// Shared look for a primary section's title bar: shaded so it reads as a
 /// distinct band rather than blending into the section body below it.

webapp/src/components/Dashboards.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useRef, useState } from 'react'
-import type { TimeRange, TimeRangePresetId } from './LogTimeline'
+import type { TimeRange, TimeRangePresetId } from '../lib/timeRange'
 import { PanelChart } from './PanelChart'
 import {
   ApiError,

webapp/src/components/LogTimeline.tsx

@@ -1,34 +1,9 @@
 import { useRef, useState } from 'react'
 import type { TimelineBucket } from '../lib/api'
+import { TIME_RANGE_PRESETS, type TimeRange, type TimeRangePresetId } from '../lib/timeRange'
 import { sectionHeaderClassName, sectionHeaderLeftClassName } from './CollapsibleSection'
 import { HelpIcon } from './HelpIcon'
 
-export interface TimeRange {
-  startMs: number
-  endMs: number
-}
-
-// `'all'` clears the range (the implicit default); the rest resolve to a window ending "now" at the moment they're (re-)computed — see `computePresetRange`.
-export type TimeRangePresetId = 'all' | '1m' | '2m' | '5m' | '15m' | '1h' | '24h'
-
-export const TIME_RANGE_PRESETS: { id: TimeRangePresetId; label: string; ms: number | null }[] = [
-  { id: 'all', label: 'All', ms: null },
-  { id: '1m', label: '1m', ms: 60 * 1000 },
-  { id: '2m', label: '2m', ms: 2 * 60 * 1000 },
-  { id: '5m', label: '5m', ms: 5 * 60 * 1000 },
-  { id: '15m', label: '15m', ms: 15 * 60 * 1000 },
-  { id: '1h', label: '1h', ms: 60 * 60 * 1000 },
-  { id: '24h', label: '24h', ms: 24 * 60 * 60 * 1000 },
-]
-
-// Callers re-invoke this on their existing poll cadence (see `App.tsx`) to keep a rolling preset's window moving with time, rather than freezing it at selection time.
-export function computePresetRange(id: TimeRangePresetId): TimeRange | null {
-  const preset = TIME_RANGE_PRESETS.find((p) => p.id === id)
-  if (!preset || preset.ms == null) return null
-  const now = Date.now()
-  return { startMs: now - preset.ms, endMs: now }
-}
-
 /// Buckets a fixed range into this many slots, so e.g. a rolling `5m` preset always requests a resolution fine enough to visibly slide instead of a handful of coarse, jumpy bars.
 const TIMELINE_TARGET_BUCKETS = 60
 

webapp/src/components/Metrics.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useState } from 'react'
-import type { TimeRange, TimeRangePresetId } from './LogTimeline'
+import type { TimeRange, TimeRangePresetId } from '../lib/timeRange'
 import {
   ApiError,
   declareMetric,

webapp/src/components/PanelChart.tsx

@@ -14,7 +14,7 @@ import {
   YAxis,
 } from 'recharts'
 import type { ChartType, PromqlSeries } from '../lib/api'
-import type { TimeRange } from './LogTimeline'
+import type { TimeRange } from '../lib/timeRange'
 
 /// Renders a label combination as a series key/legend string, e.g. `{"path":"/a"}` -> `path=/a`; no labels renders as `value`.
 export function seriesLabel(labels: Record<string, string>): string {