Merge pull request #88 from AmanTahiliani/feat/issue-87-live-correct-fp-q-timing-truth-hierarchy

[Live] Correct FP/Q timing truth, hierarchy, and mobile navigation (#87)

frontend/src/components/Nav.tsx

@@ -1,6 +1,17 @@
 import { Link } from '@tanstack/react-router'
+import { useQuery } from '@tanstack/react-query'
+import { fetchLiveState } from '../api'
+import { isLiveSessionActive } from '../lib/live'
 
 export function Nav() {
+  const { data: liveState } = useQuery({
+    queryKey: ['live-state'],
+    queryFn: fetchLiveState,
+    staleTime: 5_000,
+    refetchInterval: 30_000,
+  })
+  const liveActive = isLiveSessionActive(liveState)
+
   return (
     <nav className="app-nav">
       <Link to="/" className="nav-logo">
@@ -10,8 +21,16 @@ export function Nav() {
         <Link to="/" activeProps={{ className: 'active' }} activeOptions={{ exact: true }}>
           Command
         </Link>
-        <Link to="/live" activeProps={{ className: 'active' }}>
+        <Link
+          to="/live"
+          className={liveActive ? 'nav-live nav-live-on' : 'nav-live'}
+          activeProps={{ className: 'active' }}
+          data-testid="nav-live"
+          data-live-active={liveActive ? 'true' : 'false'}
+        >
+          {liveActive && <span className="nav-live-dot" aria-hidden="true" />}
           Live
+          {liveActive && <span className="sr-only"> session active</span>}
         </Link>
         <Link to="/race-hub" search={{}} activeProps={{ className: 'active' }}>
           Race Hub

frontend/src/components/RaceStoryCanvas.tsx

@@ -26,6 +26,12 @@ const CHART_PR = 48
 const CHART_PT = 8
 const CHART_PB = 20
 
+interface ChartTiming {
+  tMin: number
+  tMax: number
+  tRange: number
+}
+
 interface Props {
   data: {
     results: EnrichedResult[]
@@ -42,6 +48,48 @@ interface Props {
   }
 }
 
+/**
+ * Position samples are recorded for the entire session, including the pre-race
+ * grid period.  Use the winning driver's laps to define the race window so
+ * that the x-axis starts at lights-out rather than at the earliest sample.
+ */
+function raceChartTiming(
+  positions: PositionSample[],
+  laps: Lap[],
+  results: EnrichedResult[],
+): ChartTiming | null {
+  const positionTimes = positions
+    .map((position) => new Date(position.date).getTime())
+    .filter(Number.isFinite)
+  if (positionTimes.length === 0) return null
+
+  const fallbackMin = Math.min(...positionTimes)
+  const fallbackMax = Math.max(...positionTimes)
+  const fallback = {
+    tMin: fallbackMin,
+    tMax: fallbackMax,
+    tRange: Math.max(fallbackMax - fallbackMin, 1),
+  }
+
+  const winner = results.find((result) => result.position === 1)
+  if (!winner) return fallback
+
+  const winnerLaps = laps
+    .filter((lap) => lap.driver_number === winner.driver_number && lap.lap_number > 0)
+    .map((lap) => ({ ...lap, start: new Date(lap.date_start).getTime() }))
+    .filter((lap) => Number.isFinite(lap.start))
+    .sort((a, b) => a.lap_number - b.lap_number)
+  if (winnerLaps.length === 0) return fallback
+
+  const firstLap = winnerLaps[0]
+  const lastLap = winnerLaps[winnerLaps.length - 1]
+  const finalLapDuration = lastLap.lap_duration ?? 0
+  const tMax = lastLap.start + (finalLapDuration > 0 ? finalLapDuration * 1000 : 0)
+  if (tMax <= firstLap.start) return fallback
+
+  return { tMin: firstLap.start, tMax, tRange: tMax - firstLap.start }
+}
+
 export function RaceStoryCanvas({ data }: Props) {
   const {
     results,
@@ -69,14 +117,8 @@ export function RaceStoryCanvas({ data }: Props) {
   const svgRef = useRef<SVGSVGElement>(null)
   const tourRef = useRef({ chapterIndex: 0, startedAt: 0, durationMs: 0, startScrub: 0, endScrub: 0 })
 
-  const allTimes = useMemo(() => [...new Set(positions.map((p) => p.date))].sort(), [positions])
-  const hasChartData = hasPositions && allTimes.length > 0
-  const chartTiming = useMemo(() => {
-    if (!hasChartData) return null
-    const tMin = new Date(allTimes[0]).getTime()
-    const tMax = new Date(allTimes[allTimes.length - 1]).getTime()
-    return { tMin, tMax, tRange: Math.max(tMax - tMin, 1) }
-  }, [allTimes, hasChartData])
+  const chartTiming = useMemo(() => raceChartTiming(positions, laps, results), [laps, positions, results])
+  const hasChartData = hasPositions && chartTiming !== null
   const circuitKey = session?.circuit_key ?? meeting?.circuit_key ?? 0
   const outlineYear = meeting?.year ?? (session?.date_start ? new Date(session.date_start).getFullYear() : 0)
   const canProbeMap = Boolean(session?.session_key) && circuitKey > 0 && outlineYear > 0
@@ -237,12 +279,15 @@ export function RaceStoryCanvas({ data }: Props) {
 
   if (hasChartData && chartTiming) {
     const { tMin, tRange } = chartTiming
+    const normaliseTime = (time: number) => Math.max(0, Math.min(1, (time - tMin) / tRange))
 
     const byDriver = new Map<number, Array<{ t: number; pos: number }>>()
     for (const p of positions) {
+      const time = new Date(p.date).getTime()
+      if (!Number.isFinite(time)) continue
       if (!byDriver.has(p.driver_number)) byDriver.set(p.driver_number, [])
       byDriver.get(p.driver_number)!.push({
-        t: (new Date(p.date).getTime() - tMin) / tRange,
+        t: normaliseTime(time),
         pos: p.position,
       })
     }
@@ -306,12 +351,15 @@ export function RaceStoryCanvas({ data }: Props) {
     const lapTicks: { lap: number; t: number }[] = []
     const lapInterval = winnerLaps.length < 30 ? 5 : 10
 
-    for (const lap of winnerLaps) {
+    for (let i = 0; i < winnerLaps.length; i++) {
+      const lap = winnerLaps[i]
       if (lap.lap_number > 0 && lap.lap_number % lapInterval === 0) {
-        const t = (new Date(lap.date_start).getTime() - tMin) / tRange
-        if (t >= 0 && t <= 1) {
-          lapTicks.push({ lap: lap.lap_number, t })
-        }
+        const lapStart = new Date(lap.date_start).getTime()
+        const nextLapStart = winnerLaps[i + 1] ? new Date(winnerLaps[i + 1].date_start).getTime() : NaN
+        const lapEnd = lap.lap_duration && lap.lap_duration > 0
+          ? lapStart + lap.lap_duration * 1000
+          : nextLapStart
+        if (Number.isFinite(lapEnd)) lapTicks.push({ lap: lap.lap_number, t: normaliseTime(lapEnd) })
       }
     }
 
@@ -369,7 +417,10 @@ export function RaceStoryCanvas({ data }: Props) {
       clearChapterSelection()
       if (!svgRef.current) return
       const rect = svgRef.current.getBoundingClientRect()
-      const x = e.clientX - rect.left
+      if (rect.width <= 0) return
+      // Pointer coordinates are CSS pixels; convert them to the SVG viewBox
+      // before comparing with the fixed chart margins and plot width.
+      const x = ((e.clientX - rect.left) / rect.width) * W
       const t = Math.max(0, Math.min(1, (x - PL) / plotW))
       setScrubTime(t)
     }
@@ -491,8 +542,9 @@ export function RaceStoryCanvas({ data }: Props) {
                 />
 
                 {driverPits.map((p, i) => {
-                  const t = (new Date(p.date).getTime() - tMin) / tRange
-                  if (t < 0 || t > 1) return null
+                  const time = new Date(p.date).getTime()
+                  if (!Number.isFinite(time) || time < tMin || time > tMin + tRange) return null
+                  const t = normaliseTime(time)
                   const pos = getInterpPos(samples, t)
                   if (pos === null) return null
                   return (
@@ -546,6 +598,7 @@ export function RaceStoryCanvas({ data }: Props) {
             width={plotW}
             height={plotH}
             fill="transparent"
+            data-testid="position-chart-interaction"
             onPointerMove={handlePointerMove}
             onPointerLeave={() => {
               if (!isPlaying) {

frontend/src/components/live/RaceControlFeed.tsx

@@ -80,7 +80,9 @@ export function RaceControlFeed({ messages, driverInfo }: Props) {
     <section className="live-rc panel-glass">
       <div className="sec-header sticky-header">
         <span className="sec-title">Race Control</span>
-        {messages.length > 0 && <span className="sec-meta">{messages.length} messages</span>}
+        <span className="sec-meta" data-testid="rc-timezone">
+          {messages.length > 0 ? `${messages.length} messages · ` : ''}times UTC
+        </span>
       </div>
       {latest.length === 0 ? (
         <div className="missing-notice">No race control messages in the current live snapshot.</div>
@@ -102,7 +104,7 @@ export function RaceControlFeed({ messages, driverInfo }: Props) {
 
             return (
               <div className={`live-rc-row${flashClass}`} key={key}>
-                <span className="rc-time">{message.Time || '--:--'}</span>
+                <span className="rc-time" title="UTC">{message.Time || '--:--'}</span>
                 {message.Lap > 0 && <span className="rc-lap">L{message.Lap}</span>}
                 {message.Flag
                   ? <span className={`rc-flag ${rcFlagClass(message.Flag)}`}>{message.Flag}</span>

frontend/src/components/live/SessionBanner.tsx

@@ -38,9 +38,11 @@ export function SessionBanner({ isLive, isArchive = false, snapshot, rows, conne
           <div className="live-banner-meta">
             {display.advanceCount && <span>{display.advanceCount} advance</span>}
             {atRiskLabel && <span>{atRiskLabel}</span>}
-            <span>
-              L<strong>{snapshot.CurrentLap || '-'}</strong>/<strong>{snapshot.TotalLaps || '-'}</strong>
-            </span>
+            {display.isRace && (
+              <span data-testid="live-lap-counter">
+                L<strong>{snapshot.CurrentLap || '-'}</strong>/<strong>{snapshot.TotalLaps || '-'}</strong>
+              </span>
+            )}
             <span className={isLive ? 'live-state live-state-on' : 'live-state'}>{stateLabel}</span>
           </div>
         </div>

frontend/src/components/live/TimingTower.tsx

@@ -1,9 +1,10 @@
-import { useState, Fragment } from 'react'
+import { useState, useMemo, Fragment } from 'react'
 import { teamColor } from '../../utils'
 import { useAutoAnimate } from '@formkit/auto-animate/react'
 import type { LiveSessionMeta, LiveStintData } from '../../types'
 import type { LiveTimingRow } from '../../lib/live'
 import {
+  bestLapGaps,
   driverCode,
   liveSessionDisplay,
   positionDelta,
@@ -62,6 +63,10 @@ export function TimingTower({
   const isQuali = sessionDisplay.isQualifying || !isRace
   const columnCount = 7 + (isRace ? 3 : 0) + (isQuali ? 3 : 0)
 
+  // Practice/qualifying: derive a display-only gap to P1 from valid best laps
+  // when the upstream feed omits GapToLeader. Empty for races (feed is truth).
+  const practiceGaps = useMemo(() => bestLapGaps(isRace ? [] : rows), [isRace, rows])
+
   return (
     <div className="scroll-x">
       <table className="data-table live-tower" style={{ minWidth: 760 }}>
@@ -71,9 +76,9 @@ export function TimingTower({
             {isRace && <th>Δ</th>}
             <th>Driver</th>
             <th>Tyre</th>
-            <th>Last Lap</th>
-            <th 
-              className="interactive" 
+            <th className={isRace ? undefined : 'hide-mobile'}>Last Lap</th>
+            <th
+              className="interactive"
               onClick={() => setGapMode(g => g === 'interval' ? 'leader' : 'interval')}
               title="Click to toggle Gap vs Interval"
               style={{ cursor: 'pointer', textDecoration: 'underline' }}
@@ -81,10 +86,10 @@ export function TimingTower({
               {gapMode === 'interval' && isRace ? 'Interval' : 'Gap to P1'}
             </th>
             {isRace && <th>Trend</th>}
-            {isQuali && <th>S1</th>}
-            {isQuali && <th>S2</th>}
-            {isQuali && <th>S3</th>}
-            <th className="hide-mobile">Best</th>
+            {isQuali && <th className="hide-mobile">S1</th>}
+            {isQuali && <th className="hide-mobile">S2</th>}
+            {isQuali && <th className="hide-mobile">S3</th>}
+            <th className={isRace ? 'hide-mobile' : undefined}>Best</th>
             {isRace && <th className="hide-mobile r">Laps</th>}
             <th className="r"></th>
           </tr>
@@ -102,7 +107,15 @@ export function TimingTower({
               driver.Cutoff
             const showCutoffAfter = row.Position === sessionDisplay.cutoffPosition
 
-            const gapText = gapMode === 'interval' && isRace ? (driver.Interval || driver.GapToLeader) : driver.GapToLeader
+            let gapText: string
+            if (isRace) {
+              gapText = gapMode === 'interval' ? (driver.Interval || driver.GapToLeader) : driver.GapToLeader
+            } else if (driver.GapToLeader) {
+              gapText = driver.GapToLeader
+            } else {
+              const computed = practiceGaps[row.RacingNumber]
+              gapText = computed ? (computed.isLeader ? '—' : computed.gap) : ''
+            }
             const intervalAnnotation =
               gapMode === 'interval' && isRace && row.Position > 1
                 ? intervalMeaning(parseIntervalSeconds(gapText))
@@ -153,7 +166,10 @@ export function TimingTower({
                   <td>
                     <span className={`tyre-badge ${tyreClass(row.Tyre)}`}>{tyreLabel(row.Tyre)}</span>
                   </td>
-                  <td className={driver.LastLapOB ? 'mono lap-ob' : driver.LastLapPB ? 'mono lap-pb' : 'mono'}>
+                  <td className={[
+                    isRace ? '' : 'hide-mobile',
+                    driver.LastLapOB ? 'mono lap-ob' : driver.LastLapPB ? 'mono lap-pb' : 'mono',
+                  ].filter(Boolean).join(' ')}>
                     {driver.LastLapTime || '-'}
                   </td>
                   <td className="mono">
@@ -171,11 +187,14 @@ export function TimingTower({
                     </td>
                   )}
 
-                  {isQuali && <td>{renderSector(0)}</td>}
-                  {isQuali && <td>{renderSector(1)}</td>}
-                  {isQuali && <td>{renderSector(2)}</td>}
+                  {isQuali && <td className="hide-mobile">{renderSector(0)}</td>}
+                  {isQuali && <td className="hide-mobile">{renderSector(1)}</td>}
+                  {isQuali && <td className="hide-mobile">{renderSector(2)}</td>}
 
-                  <td className={`hide-mobile ${driver.BestLapOB ? 'mono lap-ob' : 'mono'}`}>
+                  <td className={[
+                    isRace ? 'hide-mobile' : '',
+                    driver.BestLapOB ? 'mono lap-ob' : 'mono',
+                  ].filter(Boolean).join(' ')}>
                     {driver.BestLapTime || '-'}
                   </td>
                   
@@ -208,6 +227,16 @@ export function TimingTower({
                                  <div className="mono">{driver.NumberOfLaps || 0}</div>
                               </div>
                             )}
+                            {!isRace && driver.Sectors?.some((sec) => sec?.Value) && (
+                              <div data-testid="expanded-sectors">
+                                 <div className="mono" style={{ color: 'var(--text-3)', fontSize: '10px', marginBottom: '4px' }}>SECTORS</div>
+                                 <div className="mono" style={{ display: 'flex', gap: '10px' }}>
+                                    {renderSector(0)}
+                                    {renderSector(1)}
+                                    {renderSector(2)}
+                                 </div>
+                              </div>
+                            )}
                             {driver.SpeedTrap && (
                               <div>
                                  <div className="mono" style={{ color: 'var(--text-3)', fontSize: '10px', marginBottom: '4px' }}>SPEED TRAP</div>

frontend/src/components/live/TyreDegPanel.tsx

@@ -52,7 +52,10 @@ function StintSparkline({ seconds }: { seconds: number[] }) {
 }
 
 export function TyreDegPanel({ rows, sessionType, pinned }: Props) {
-  const [collapsed, setCollapsed] = useState(false)
+  const isRace = isRaceSession(sessionType)
+  // In practice/qualifying deg trends are secondary — collapse by default so
+  // the Timing Tower stays above the fold. Races keep it open.
+  const [collapsed, setCollapsed] = useState(!isRace)
   const [stints, setStints] = useState<StintHistoryMap>({})
 
   // One lap-history update per received snapshot (rows is rebuilt per snapshot).
@@ -61,8 +64,6 @@ export function TyreDegPanel({ rows, sessionType, pinned }: Props) {
     setStints((prev) => recordStintSamples(prev, rows.map(stintInputFromRow)))
   }, [rows])
 
-  const isRace = isRaceSession(sessionType)
-
   const visible = useMemo(
     () =>
       rows.filter(

frontend/src/lib/live.ts

@@ -268,6 +268,63 @@ export function driverCode(row: LiveTimingRow): string {
   return row.Info?.Tla || row.RacingNumber
 }
 
+/**
+ * Parse an F1 lap-time string ("1:45.944", "45.944") into total seconds.
+ * Returns null for empty/invalid values so callers never invent a gap.
+ */
+export function parseLapTimeSeconds(value: string | null | undefined): number | null {
+  if (!value) return null
+  const match = value.trim().match(/^(?:(\d+):)?([0-5]?\d(?:\.\d+)?)$/)
+  if (!match) return null
+  const minutes = match[1] ? Number(match[1]) : 0
+  const seconds = Number(match[2])
+  if (!Number.isFinite(minutes) || !Number.isFinite(seconds)) return null
+  return minutes * 60 + seconds
+}
+
+export interface BestLapGap {
+  isLeader: boolean
+  gap: string
+}
+
+/**
+ * Display-only gap-to-P1 for practice/qualifying, derived from each driver's
+ * valid best lap. Only drivers with a parseable best lap get an entry, and the
+ * fastest is flagged as the leader. Never fabricates a gap from a missing or
+ * invalid lap — the upstream interval remains the source of truth for races.
+ */
+export function bestLapGaps(rows: ReadonlyArray<LiveTimingRow>): Record<string, BestLapGap> {
+  let leaderNumber = ''
+  let best = Infinity
+  for (const row of rows) {
+    const seconds = parseLapTimeSeconds(row.Driver.BestLapTime)
+    if (seconds === null) continue
+    if (seconds < best) {
+      best = seconds
+      leaderNumber = row.RacingNumber
+    }
+  }
+
+  const out: Record<string, BestLapGap> = {}
+  if (!Number.isFinite(best)) return out
+  for (const row of rows) {
+    const seconds = parseLapTimeSeconds(row.Driver.BestLapTime)
+    if (seconds === null) continue
+    out[row.RacingNumber] =
+      row.RacingNumber === leaderNumber
+        ? { isLeader: true, gap: '' }
+        : { isLeader: false, gap: `+${(seconds - best).toFixed(3)}` }
+  }
+  return out
+}
+
+/** True when the live feed reports an in-progress session with timing data. */
+export function isLiveSessionActive(
+  state: { is_live?: boolean; data?: unknown } | null | undefined,
+): boolean {
+  return Boolean(state?.is_live && state.data)
+}
+
 export function trackStatusLabel(status: string): string {
   return TRACK_STATUS_LABELS[status] || status || 'UNKNOWN'
 }

frontend/src/styles/app.css

@@ -112,6 +112,30 @@ a { color: inherit; text-decoration: none; }
 .nav-links a:hover { color: var(--text); background: var(--surface-h); }
 .nav-links a.active { color: var(--text); background: var(--surface-2); }
 
+/* Live nav gets a pulsing marker only while a session is on air. */
+.nav-live { display: inline-flex; align-items: center; gap: 6px; }
+.nav-links a.nav-live-on { color: var(--text); font-weight: 600; }
+.nav-live-dot {
+  width: 7px;
+  height: 7px;
+  border-radius: 50%;
+  background: var(--red);
+  box-shadow: 0 0 0 0 rgba(225, 6, 0, 0.4);
+  animation: pulse-live 1.6s infinite;
+}
+
+.sr-only {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}
+
 .nav-utility {
   margin-left: auto;
   display: flex;

frontend/src/test/LiveComponents.test.tsx

@@ -209,6 +209,32 @@ describe('TimingTower', () => {
     expect(screen.getByText('DRS range')).toBeInTheDocument()
   })
 
+  it('derives a gap to P1 from best laps when the practice feed omits GapToLeader', () => {
+    const practiceRows = [
+      makeRow('1', 1, 'VER', { BestLapTime: '1:45.944', GapToLeader: '' }),
+      makeRow('4', 2, 'NOR', { BestLapTime: '1:46.134', GapToLeader: '' }),
+      makeRow('16', 3, 'LEC', { BestLapTime: '', GapToLeader: '' }),
+    ]
+    render(
+      <TimingTower
+        rows={practiceRows}
+        session={{
+          MeetingName: 'Belgian Grand Prix',
+          CircuitName: 'Spa',
+          SessionType: 'Practice',
+          SessionName: 'Practice 2',
+          Path: '',
+        }}
+      />,
+    )
+    // Leader shows a clear leader marker, not a fabricated gap.
+    expect(screen.getByText('VER').closest('tr')).toHaveTextContent('—')
+    expect(screen.getByText('+0.190')).toBeInTheDocument()
+    // A driver without a valid best lap gets no invented gap.
+    const lecRow = screen.getByText('LEC').closest('tr')!
+    expect(lecRow).not.toHaveTextContent('+')
+  })
+
   it('renders the SQ1 cutoff after P17 and marks rows below as at risk', () => {
     const sprintRows = Array.from({ length: 22 }, (_, index) =>
       makeRow(String(index + 1), index + 1, `D${index + 1}`),

frontend/src/test/LiveTimingPage.test.tsx

@@ -153,6 +153,29 @@ describe('LiveTimingPage archive mode', () => {
     expect(screen.queryByRole('button', { name: /view last session/i })).not.toBeInTheDocument()
   })
 
+  it('renders the live session for a red-flag paused snapshot instead of the inactive empty state', async () => {
+    renderPage({
+      is_live: true,
+      data: {
+        ...archivedSnapshot,
+        SessionStatus: 'Inactive',
+        TrackStatus: '2',
+        Clock: '00:03:27',
+        Session: {
+          MeetingName: 'Belgian Grand Prix',
+          CircuitName: 'Spa-Francorchamps',
+          SessionType: 'Practice',
+          SessionName: 'Practice 2',
+          Path: '',
+        },
+      },
+    })
+
+    expect(await screen.findByText('Timing Tower')).toBeInTheDocument()
+    expect(screen.queryByTestId('live-empty')).not.toBeInTheDocument()
+    expect(screen.queryByTestId('live-archive-strip')).not.toBeInTheDocument()
+  })
+
   it('temporarily omits the track map while live GPS is unavailable', async () => {
     renderPage({
       is_live: true,

frontend/src/test/RaceStoryCanvas.test.tsx

@@ -179,6 +179,57 @@ describe('RaceStoryCanvas replay map', () => {
     expect(document.querySelector('.rs-replay-shell--split')).not.toBeInTheDocument()
   })
 
+  it('uses lap timing rather than pre-race position samples for the chart scale', () => {
+    const laps = Array.from({ length: 20 }, (_, index) => ({
+      session_key: 99,
+      driver_number: 1,
+      meeting_key: 1,
+      lap_number: index + 1,
+      date_start: `2025-05-25T13:${String(index).padStart(2, '0')}:00Z`,
+      lap_duration: 60,
+      is_pit_out_lap: false,
+    }))
+
+    renderCanvas({
+      results: [{ ...raceHub.results[0], number_of_laps: 20 }],
+      laps,
+      positions: [
+        { session_key: 99, driver_number: 1, meeting_key: 1, date: '2025-05-25T12:00:00Z', position: 1 },
+        { session_key: 99, driver_number: 1, meeting_key: 1, date: '2025-05-25T13:20:00Z', position: 1 },
+      ],
+    })
+
+    // L10 is the end of the tenth 60s lap, exactly halfway through the race.
+    const lapTenLabel = screen.getByText('L10')
+    expect(lapTenLabel.previousElementSibling).toHaveAttribute('x1', '316')
+    // The pre-race position is retained as the starting grid at the left edge.
+    expect(document.querySelector('.rs-driver-line')).toHaveAttribute('points', '40,8 592,8 592,8')
+  })
+
+  it('maps cursor positions from rendered pixels to the SVG viewBox', () => {
+    renderCanvas()
+
+    const svg = document.querySelector('.rs-position-chart-svg')!
+    vi.spyOn(svg, 'getBoundingClientRect').mockReturnValue({
+      x: 0,
+      y: 0,
+      width: 1280,
+      height: 360,
+      top: 0,
+      right: 1280,
+      bottom: 360,
+      left: 0,
+      toJSON: () => ({}),
+    })
+
+    const pointerMove = new Event('pointermove', { bubbles: true })
+    Object.defineProperty(pointerMove, 'clientX', { value: 640 })
+    fireEvent(screen.getByTestId('position-chart-interaction'), pointerMove)
+
+    // 640px is the middle of a 1280px rendered chart, which is x=320 in its 640-unit viewBox.
+    expect(document.querySelector('.rs-playhead')).toHaveAttribute('x1', '320')
+  })
+
   it('syncs active chapter highlight when a chapter card is clicked', async () => {
     renderCanvas()
 

frontend/src/test/SessionBanner.test.tsx

@@ -0,0 +1,61 @@
+import { describe, expect, it } from 'vitest'
+import { render, screen } from '@testing-library/react'
+import { SessionBanner } from '../components/live/SessionBanner'
+import type { LiveStreamData } from '../types'
+
+function makeSnapshot(sessionType: string, sessionName: string): LiveStreamData {
+  return {
+    Drivers: {},
+    DriverInfo: {},
+    Tyres: {},
+    RCMessages: [],
+    Weather: { AirTemp: 0, TrackTemp: 0, Humidity: 0, WindSpeed: 0, WindDir: 0, Rainfall: false },
+    Session: {
+      MeetingName: 'Belgian Grand Prix',
+      CircuitName: 'Spa-Francorchamps',
+      SessionType: sessionType,
+      SessionName: sessionName,
+      Path: '',
+    },
+    TeamRadio: [],
+    TrackStatus: '1',
+    CurrentLap: 0,
+    TotalLaps: 0,
+    Clock: '00:45:00',
+    ClockRefTime: '',
+    ClockExtrapolating: false,
+    Stints: {},
+  }
+}
+
+describe('SessionBanner', () => {
+  it('never renders a race lap counter for a practice session', () => {
+    render(
+      <SessionBanner
+        isLive
+        snapshot={makeSnapshot('Practice', 'Practice 2')}
+        rows={[]}
+        connection="connected"
+        now={0}
+      />,
+    )
+    expect(screen.queryByTestId('live-lap-counter')).not.toBeInTheDocument()
+    // Session identity and clock stay intact.
+    expect(screen.getByText('Belgian Grand Prix')).toBeInTheDocument()
+    expect(screen.getByTestId('live-clock')).toHaveTextContent('00:45:00')
+  })
+
+  it('shows the lap counter for a race session', () => {
+    const snapshot = { ...makeSnapshot('Race', 'Race'), CurrentLap: 12, TotalLaps: 44 }
+    render(
+      <SessionBanner
+        isLive
+        snapshot={snapshot}
+        rows={[]}
+        connection="connected"
+        now={0}
+      />,
+    )
+    expect(screen.getByTestId('live-lap-counter')).toHaveTextContent('L12/44')
+  })
+})

frontend/src/test/TyreDegPanel.test.tsx

@@ -81,14 +81,20 @@ describe('TyreDegPanel', () => {
     expect(panel).toHaveTextContent('→ ~P2')
   })
 
-  it('hides the rejoin estimate outside race sessions and collapses on toggle', () => {
+  it('collapses by default outside race sessions and hides the rejoin estimate when expanded', () => {
     render(<TyreDegPanel rows={snapshotRows(3, '1:30.000')} sessionType="Qualifying" pinned={[]} />)
     const panel = screen.getByTestId('tyredeg-panel')
-    expect(panel).not.toHaveTextContent('~P')
 
-    expect(screen.getAllByTestId('tyredeg-row')).toHaveLength(2)
-    fireEvent.click(screen.getByRole('button', { name: /tyre deg/i }))
+    // Practice/qualifying starts collapsed so the Timing Tower stays above the fold.
     expect(screen.queryAllByTestId('tyredeg-row')).toHaveLength(0)
+    fireEvent.click(screen.getByRole('button', { name: /tyre deg/i }))
+    expect(screen.getAllByTestId('tyredeg-row')).toHaveLength(2)
+    expect(panel).not.toHaveTextContent('~P')
+  })
+
+  it('starts expanded during a race', () => {
+    render(<TyreDegPanel rows={snapshotRows(3, '1:30.000')} sessionType="Race" pinned={[]} />)
+    expect(screen.getAllByTestId('tyredeg-row')).toHaveLength(2)
   })
 
   it('limits rows to the top ten plus pinned drivers', () => {

frontend/src/test/live.test.ts

@@ -1,12 +1,15 @@
 import { describe, expect, it } from 'vitest'
 import {
+  bestLapGaps,
   compoundClass,
   compoundLetter,
   extrapolateClock,
+  isLiveSessionActive,
   latestRaceControl,
   liveSessionDisplay,
   loadPinnedDrivers,
   mergeVisibleSectors,
+  parseLapTimeSeconds,
   positionDeltaClass,
   parseLiveStateEvent,
   rcFlagClass,
@@ -279,6 +282,43 @@ describe('live qualifying display', () => {
   })
 })
 
+describe('practice/qualifying computed gaps', () => {
+  it('parses lap-time strings into seconds and rejects invalid input', () => {
+    expect(parseLapTimeSeconds('1:45.944')).toBeCloseTo(105.944, 3)
+    expect(parseLapTimeSeconds('45.944')).toBeCloseTo(45.944, 3)
+    expect(parseLapTimeSeconds('')).toBeNull()
+    expect(parseLapTimeSeconds(undefined)).toBeNull()
+    expect(parseLapTimeSeconds('-')).toBeNull()
+    expect(parseLapTimeSeconds('nope')).toBeNull()
+  })
+
+  it('derives a gap to P1 from valid best laps only, flagging the leader', () => {
+    const gaps = bestLapGaps([
+      timingRow('1', 1, { BestLapTime: '1:45.944' }),
+      timingRow('4', 2, { BestLapTime: '1:46.134' }),
+      timingRow('16', 3, { BestLapTime: '' }),
+    ])
+    expect(gaps['1']).toEqual({ isLeader: true, gap: '' })
+    expect(gaps['4']).toEqual({ isLeader: false, gap: '+0.190' })
+    // No valid best lap → no fabricated gap.
+    expect(gaps['16']).toBeUndefined()
+  })
+
+  it('returns no gaps when nobody has set a lap', () => {
+    expect(bestLapGaps([timingRow('1', 1, { BestLapTime: '' })])).toEqual({})
+  })
+})
+
+describe('live session activity', () => {
+  it('is active only when the feed reports a live session with data', () => {
+    expect(isLiveSessionActive({ is_live: true, data: snapshot })).toBe(true)
+    expect(isLiveSessionActive({ is_live: true, data: null })).toBe(false)
+    expect(isLiveSessionActive({ is_live: false, data: snapshot })).toBe(false)
+    expect(isLiveSessionActive(null)).toBe(false)
+    expect(isLiveSessionActive(undefined)).toBe(false)
+  })
+})
+
 describe('visible sector display', () => {
   it('holds S1 and S2 through temporary blanks while a flying lap is active', () => {
     const first = [timingRow('4', 1, {

internal/live/parser_test.go

@@ -307,6 +307,28 @@ func TestSessionStatusIsActive(t *testing.T) {
 	}
 }
 
+func TestSessionStatusIsTerminal(t *testing.T) {
+	tests := []struct {
+		status string
+		want   bool
+	}{
+		{"Finished", true},
+		{"Finalised", true},
+		{"Finalized", true},
+		{"Ends", true},
+		{"Aborted", true},
+		{"Started", false},
+		{"Resumed", false},
+		{"Inactive", false},
+		{"", false},
+	}
+	for _, tt := range tests {
+		if got := live.SessionStatusIsTerminal(tt.status); got != tt.want {
+			t.Errorf("SessionStatusIsTerminal(%q) = %v, want %v", tt.status, got, tt.want)
+		}
+	}
+}
+
 func TestProcessTopicRaceControlMessages(t *testing.T) {
 	state := live.NewState()
 	data := json.RawMessage(`{

internal/live/types.go

@@ -186,6 +186,19 @@ func SessionStatusIsActive(status string) bool {
 	}
 }
 
+// SessionStatusIsTerminal reports whether a raw F1 live timing SessionStatus
+// value represents a session that has ended and will not resume. A temporarily
+// inactive session (e.g. a red-flag pause reported as "Inactive") is neither
+// active nor terminal.
+func SessionStatusIsTerminal(status string) bool {
+	switch normalizeSessionStatus(status) {
+	case "finished", "finalised", "finalized", "ends", "aborted":
+		return true
+	default:
+		return false
+	}
+}
+
 func normalizeSessionStatus(status string) string {
 	out := make([]rune, 0, len(status))
 	for _, r := range status {

internal/web/live.go

@@ -134,7 +134,7 @@ func (h *SSEHub) applySnapshot(data live.LiveStreamData, now time.Time) liveStat
 	h.mu.Lock()
 	defer h.mu.Unlock()
 
-	if live.SessionStatusIsActive(data.SessionStatus) {
+	if snapshotIsLive(data) {
 		h.isLive = true
 		h.activeSnapshot = &data
 		if data.PositionUpdated && len(data.Positions) > 0 {
@@ -208,6 +208,40 @@ func (h *SSEHub) stateLocked() liveStatePayload {
 	return payload
 }
 
+// snapshotIsLive reports whether the current live-timing snapshot represents an
+// ongoing session that should be surfaced as live.
+//
+// An actively running session (Started/Resumed) is always live. A non-terminal
+// but temporarily inactive session — e.g. a red-flag pause where SessionStatus
+// drops to "Inactive" while the session is still in progress — is also live when
+// the snapshot itself carries live evidence: a session clock with time remaining
+// plus session metadata. This keeps the paused track state visible instead of
+// collapsing to the inactive empty state.
+//
+// Terminal sessions (Finished/Finalised/Ends/Aborted) are never live. A generic
+// inactive/no-session stale snapshot is not live either: the predicate keys off
+// the current snapshot's clock and session, so old metadata alone is not enough.
+func snapshotIsLive(data live.LiveStreamData) bool {
+	if live.SessionStatusIsActive(data.SessionStatus) {
+		return true
+	}
+	if live.SessionStatusIsTerminal(data.SessionStatus) {
+		return false
+	}
+	return clockHasTimeRemaining(data.Clock) && data.Session.SessionName != ""
+}
+
+// clockHasTimeRemaining reports whether an "HH:MM:SS" session clock has any time
+// left. Empty or all-zero clocks (a spent or absent session) return false.
+func clockHasTimeRemaining(clock string) bool {
+	for _, r := range clock {
+		if r >= '1' && r <= '9' {
+			return true
+		}
+	}
+	return false
+}
+
 func hasLiveSnapshotData(data live.LiveStreamData) bool {
 	return len(data.Drivers) > 0 ||
 		len(data.DriverInfo) > 0 ||

internal/web/live_archive_test.go

@@ -51,6 +51,101 @@ func TestSSEHubArchivesTerminalSessionSnapshot(t *testing.T) {
 	}
 }
 
+func TestSnapshotIsLive(t *testing.T) {
+	redFlag := live.LiveStreamData{
+		SessionStatus: "Inactive",
+		TrackStatus:   "2",
+		Clock:         "00:03:27",
+		Session:       live.LiveSessionMeta{MeetingName: "Belgian Grand Prix", SessionName: "Practice 2", SessionType: "Practice"},
+	}
+	tests := []struct {
+		name string
+		data live.LiveStreamData
+		want bool
+	}{
+		{"started", live.LiveStreamData{SessionStatus: "Started"}, true},
+		{"resumed", live.LiveStreamData{SessionStatus: "Resumed"}, true},
+		{"red flag inactive with clock and session", redFlag, true},
+		{"terminal finished with clock", func() live.LiveStreamData {
+			d := redFlag
+			d.SessionStatus = "Finished"
+			return d
+		}(), false},
+		{"inactive spent clock", func() live.LiveStreamData {
+			d := redFlag
+			d.Clock = "00:00:00"
+			return d
+		}(), false},
+		{"inactive no clock", func() live.LiveStreamData {
+			d := redFlag
+			d.Clock = ""
+			return d
+		}(), false},
+		{"inactive no session metadata", func() live.LiveStreamData {
+			d := redFlag
+			d.Session = live.LiveSessionMeta{}
+			return d
+		}(), false},
+	}
+	for _, tt := range tests {
+		if got := snapshotIsLive(tt.data); got != tt.want {
+			t.Errorf("%s: snapshotIsLive = %v, want %v", tt.name, got, tt.want)
+		}
+	}
+}
+
+func TestSSEHubKeepsRedFlagSessionLive(t *testing.T) {
+	hub := newSSEHub()
+	now := time.Date(2026, 7, 26, 14, 0, 0, 0, time.UTC)
+
+	redFlag := live.LiveStreamData{
+		SessionStatus:   "Inactive",
+		TrackStatus:     "2",
+		Clock:           "00:03:27",
+		Session:         live.LiveSessionMeta{MeetingName: "Belgian Grand Prix", SessionName: "Practice 2", SessionType: "Practice"},
+		SnapshotUpdated: true,
+	}
+	state := hub.applySnapshot(redFlag, now)
+
+	if !state.IsLive {
+		t.Fatal("red-flag paused session should report is_live=true")
+	}
+	if state.Data == nil {
+		t.Fatal("red-flag paused session must still send the active snapshot")
+	}
+	if state.Data.TrackStatus != "2" {
+		t.Fatalf("track status = %q, want the paused state \"2\"", state.Data.TrackStatus)
+	}
+	if state.LastSnapshot != nil {
+		t.Fatalf("red-flag session should not be archived: %+v", state.LastSnapshot)
+	}
+}
+
+func TestSSEHubStaleInactiveSnapshotNotLive(t *testing.T) {
+	hub := newSSEHub()
+	now := time.Date(2026, 7, 26, 14, 0, 0, 0, time.UTC)
+
+	// Inactive snapshot with session metadata but no remaining clock: this is a
+	// stale/no-live-evidence snapshot and must not be surfaced as live.
+	stale := live.LiveStreamData{
+		SessionStatus:   "Inactive",
+		Clock:           "00:00:00",
+		Session:         live.LiveSessionMeta{MeetingName: "Belgian Grand Prix", SessionName: "Practice 2"},
+		SnapshotUpdated: true,
+	}
+	state := hub.applySnapshot(stale, now)
+
+	if state.IsLive {
+		t.Fatal("stale inactive snapshot should report is_live=false")
+	}
+	if state.Data != nil {
+		t.Fatalf("stale inactive snapshot leaked into active data: %+v", state.Data)
+	}
+	if state.LastSnapshot == nil {
+		t.Fatal("stale inactive snapshot with metadata should be archived")
+	}
+}
+
 func TestHandleLiveStateKeepsArchiveOutOfActiveData(t *testing.T) {
 	hub := newSSEHub()
 	now := time.Date(2026, 7, 4, 14, 0, 0, 0, time.UTC)

tests/live-timing.spec.ts

@@ -147,6 +147,58 @@ const sprintQualifyingSnapshot = {
   },
 }
 
+// Practice: the feed sets best laps but no GapToLeader/Interval, and there is
+// no race lap-total concept. Exercises computed gaps, the non-race banner, the
+// collapsed-by-default tyre panel, and the 390px core-field layout.
+const practiceSnapshot = {
+  is_live: true,
+  data: {
+    ...raceSnapshot.data,
+    Drivers: Object.fromEntries(
+      Array.from({ length: 10 }, (_, index) => {
+        const num = String(index + 1)
+        return [
+          num,
+          driver(num, index + 1, '', '', {
+            // Distinct, increasing best laps; P1 fastest, +0.200s per position.
+            BestLapTime: `1:${(45.9 + index * 0.2).toFixed(3).padStart(6, '0')}`,
+            LastLapTime: '1:46.500',
+            NumberOfLaps: 12,
+            Sectors: index === 0
+              ? [
+                  { Value: '28.500', PersonalFastest: true, OverallFastest: false },
+                  { Value: '52.100', PersonalFastest: false, OverallFastest: false },
+                  { Value: '25.344', PersonalFastest: false, OverallFastest: false },
+                ]
+              : [],
+          }),
+        ]
+      }),
+    ),
+    DriverInfo: Object.fromEntries(
+      Array.from({ length: 10 }, (_, index) => {
+        const num = String(index + 1)
+        return [num, info(num, `D${index + 1}`, 'Driver', String(index + 1), 'Test Team', index % 2 ? 'FF8000' : '27F4D2')]
+      }),
+    ),
+    Tyres: Object.fromEntries(
+      Array.from({ length: 10 }, (_, index) => [String(index + 1), { Compound: 'SOFT', New: false, Age: index % 4 }]),
+    ),
+    Session: {
+      MeetingName: 'Belgian Grand Prix',
+      CircuitName: 'Spa-Francorchamps',
+      SessionType: 'Practice',
+      SessionName: 'Practice 2',
+    },
+    TrackStatus: '1',
+    CurrentLap: 0,
+    TotalLaps: 0,
+    Clock: '00:45:00',
+    ClockRefTime: '2026-07-17T13:00:00Z',
+    ClockExtrapolating: false,
+  },
+}
+
 test.describe('Live Timing (mocked snapshot)', () => {
   test.beforeEach(async ({ page }) => {
     await page.route('**/api/v1/live/state', (route) =>
@@ -233,6 +285,94 @@ test.describe('Live Timing (mocked Sprint Qualifying)', () => {
   })
 })
 
+test.describe('Live Timing (mocked Practice)', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.route('**/api/v1/live/state', (route) =>
+      route.fulfill({ contentType: 'application/json', body: JSON.stringify(practiceSnapshot) }),
+    )
+    await page.route('**/api/v1/live/stream', (route) =>
+      route.fulfill({ contentType: 'text/event-stream', body: 'event: heartbeat\ndata: {}\n\n' }),
+    )
+    await page.goto('/live')
+  })
+
+  test('derives a gap to P1 from best laps and marks the leader', async ({ page }) => {
+    const tower = page.locator('.live-tower')
+    await expect(tower).toBeVisible()
+    // P1 shows a leader marker, not a fabricated gap.
+    await expect(tower.locator('tbody tr').first()).toContainText('—')
+    // P2 shows the computed +0.200 delta.
+    await expect(tower).toContainText('+0.200')
+  })
+
+  test('omits the race lap counter and keeps the session clock for practice', async ({ page }) => {
+    await expect(page.getByTestId('live-lap-counter')).toHaveCount(0)
+    await expect(page.getByTestId('live-clock')).toContainText('00:45:00')
+    await expect(page.locator('.live-banner')).not.toContainText('L-/-')
+  })
+
+  test('collapses the tyre panel by default so the tower is above the fold', async ({ page }) => {
+    await expect(page.getByTestId('tyredeg-panel')).toBeVisible()
+    await expect(page.getByTestId('tyredeg-row')).toHaveCount(0)
+    await expect(page.locator('.live-tower')).toBeVisible()
+  })
+
+  test('labels Race Control times as UTC', async ({ page }) => {
+    await expect(page.getByTestId('rc-timezone')).toContainText('UTC')
+  })
+
+  test('marks Live as active in the primary navigation', async ({ page }) => {
+    await expect(page.getByTestId('nav-live')).toHaveAttribute('data-live-active', 'true')
+    await expect(page.getByTestId('nav-live').locator('.nav-live-dot')).toBeVisible()
+  })
+})
+
+test.describe('Live Timing (390px practice viewport)', () => {
+  test.use({ viewport: { width: 390, height: 844 } })
+
+  test.beforeEach(async ({ page }) => {
+    await page.route('**/api/v1/live/state', (route) =>
+      route.fulfill({ contentType: 'application/json', body: JSON.stringify(practiceSnapshot) }),
+    )
+    await page.route('**/api/v1/live/stream', (route) =>
+      route.fulfill({ contentType: 'text/event-stream', body: 'event: heartbeat\ndata: {}\n\n' }),
+    )
+    await page.goto('/live')
+  })
+
+  test('shows the five core fields with no horizontal overflow', async ({ page }) => {
+    const tower = page.locator('.live-tower')
+    await expect(tower).toBeVisible()
+
+    // Core comparison fields are present in the header.
+    await expect(tower.locator('thead')).toContainText('Pos')
+    await expect(tower.locator('thead')).toContainText('Driver')
+    await expect(tower.locator('thead')).toContainText('Tyre')
+    await expect(tower.locator('thead')).toContainText('Best')
+    await expect(tower.locator('thead')).toContainText('Gap to P1')
+
+    // Sectors are hidden from the initial mobile tower (reachable via expand).
+    const firstSector = tower.locator('thead th', { hasText: 'S1' })
+    await expect(firstSector).toBeHidden()
+
+    // The document must not scroll horizontally.
+    const overflow = await page.evaluate(
+      () => document.documentElement.scrollWidth - document.documentElement.clientWidth,
+    )
+    expect(overflow).toBeLessThanOrEqual(0)
+  })
+
+  test('exposes sectors through the row detail interaction', async ({ page }) => {
+    // Sector columns are not in the initial mobile tower...
+    await expect(page.locator('.live-tower thead th', { hasText: 'S1' })).toBeHidden()
+    // ...but the P1 row's sectors are reachable by expanding the row.
+    await page.locator('.live-tower tbody tr', { hasText: 'D1' }).first().click()
+    const sectors = page.getByTestId('expanded-sectors')
+    await expect(sectors).toBeVisible()
+    await expect(sectors).toContainText('28.500')
+  })
+})
+
 test.describe('Live Timing (no session)', () => {
   test('shows the empty state when the feed has no snapshot', async ({ page }) => {
     await page.goto('/live')