feat: detect race replay chapters

Add deterministic server-side chapter detection for starts, flag periods, pit phases, decisive top-five swings, and finishes, then expose chapters on the race-hub payload.

Spike result: race-hub already loads race control, positions, and laps in one read model. The requested Detect signature does not include pit stops, so pit phases use IsPitOutLap clusters as the local deterministic pit-stop proxy.

.agents/README.md

@@ -24,7 +24,7 @@ bin/dev          CLI: `dev implement <issue#> --harness <name> [--dry-run]`
 - **Groom** (interactive, Claude): `/groom <issue#>` runs a seeded grill-me → writes a
   Ready spec into the issue body → sets Effort/Priority → leaves Stage at `Research`.
   You review and flip to `Ready`.
-- **Implement** (any harness): `.agents/bin/dev implement <issue#> --harness <name>`
+- **Implement** (recommended harnesses: `codex` or `cursor`): `.agents/bin/dev implement <issue#> --harness <name>`
   (or `/implement …` in Claude to supervise) → isolated worktree → runs the harness
   headless on the spec → build gate → opens a PR → sets Stage `In Review`.
 - **Review + merge**: use the `review` skill from a harness different from the
@@ -42,8 +42,17 @@ local adapter state.
 ## Adding / fixing a harness
 
 Edit one function in `harnesses.sh`: `harness_<name> <workdir> <promptfile>`, running the
-tool non-interactively in `<workdir>` on the prompt. `claude`/`codex`/`opencode` are
+tool non-interactively in `<workdir>` on the prompt. For current implementation
-wired; `pi`/`cursor` are stubs — confirm their headless flags before trusting.
+dispatch, prefer `codex` or `cursor`; `claude` and `opencode` remain available, and
+`pi` still needs flag verification before trusting.
+
+`agy` / Antigravity is deliberately disabled for non-dry-run dispatch as of
+2026-07-04. Phase 1 testing found the headless path unreliable: with
+`--new-project` it ignored the prompt and tried to scaffold, while without it the CLI
+could resume a stale conversation and hang past the print timeout. Keep using
+`.agents/bin/dev implement <issue#> --harness agy --dry-run` for prompt inspection
+only; real dispatch should use `codex` or `cursor` until a fresh Antigravity
+headless invocation is verified and documented.
 
 Always `--dry-run` a new harness first: it renders the exact prompt and plan, touching
 nothing (no worktree, PR, or state change).

.agents/bin/dev

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 # .agents/bin/dev — box-box agentic dev CLI. Works from any harness's shell.
 #
-#   dev implement <issue#> --harness <claude|codex|opencode|pi|cursor> [--dry-run] [--base <branch>]
+#   dev implement <issue#> --harness <codex|cursor|claude|opencode|pi|agy> [--dry-run] [--base <branch>]
 #
 # Grooming is driven interactively via the Claude Code /groom skill; this CLI covers
 # the implement lane (dispatch a Ready issue to a harness → worktree → gate → PR).
@@ -15,7 +15,7 @@ box-box dev CLI
 
   dev implement <issue#> --harness <name> [--dry-run] [--base <branch>]
 
-harnesses: claude, codex, opencode (supported) · pi, cursor (verify flags in .agents/harnesses.sh)
+harnesses: codex, cursor (recommended) · claude, opencode (available) · agy (dry-run only, disabled for dispatch) · pi (verify flags)
   --dry-run   render the prompt + plan, touch nothing (no worktree/PR/state change)
   --base      base branch for the worktree/PR (default: main)
 EOF

.agents/harnesses.sh

@@ -11,6 +11,18 @@
 
 # ---- MUST-HAVE ----
 
+harness_disabled_reason() {              # <name> -> reason on stdout; 0 means disabled
+  case "$1" in
+    agy)
+      cat <<'EOF'
+agy is disabled for implementation dispatch as of 2026-07-04: Antigravity headless mode was observed to ignore prompts with --new-project, resume stale conversations without it, and hang past print timeouts. Use codex or cursor until a fresh headless invocation is verified.
+EOF
+      return 0
+      ;;
+    *) return 1 ;;
+  esac
+}
+
 harness_claude() {                      # Claude Code — print mode, auto-accept edits
   local dir="$1" prompt="$2"
   ( cd "$dir" && claude -p "$(cat "$prompt")" --permission-mode acceptEdits )
@@ -31,14 +43,11 @@ harness_cursor() {                      # Cursor CLI agent — composer-2.5, hea
   ( cd "$dir" && cursor-agent -p "$(cat "$prompt")" --model composer-2.5 --force --trust )
 }
 
-harness_agy() {                         # Antigravity CLI — UNRELIABLE headless (2026-07): with
+harness_agy() {                         # Antigravity CLI — disabled until headless is verified
-  # --new-project it ignores the prompt and asks to scaffold a project; without it, it
+  local reason
-  # resumes the previous conversation (silently keeping its old model — --model only
+  reason="$(harness_disabled_reason agy)"
-  # applies to new conversations) and can hang past the print timeout. Do not trust for
+  echo "harness_agy: $reason" >&2
-  # dispatch until fixed upstream; verify with a trivial prompt first.
+  return 2
-  local dir="$1" prompt="$2"
-  ( cd "$dir" && agy --print --print-timeout 60m \
-      --model="Gemini 3.1 Pro (High)" --dangerously-skip-permissions "$(cat "$prompt")" )
 }
 
 # ---- NICE-TO-HAVE (verify the exact invocation for your version before trusting) ----

.agents/lib/dispatch.sh

@@ -52,6 +52,15 @@ dispatch() { # <issue#> <harness> [--dry-run] [--base <branch>]
   if ! declare -f "harness_$harness" >/dev/null 2>&1; then
     echo "no adapter for harness '$harness' — add harness_$harness() to .agents/harnesses.sh" >&2; return 2
   fi
+  if [ "$dry" != 1 ] && declare -f harness_disabled_reason >/dev/null 2>&1; then
+    local disabled_reason
+    if disabled_reason="$(harness_disabled_reason "$harness")"; then
+      echo "harness '$harness' is disabled for non-dry-run dispatch." >&2
+      echo "  $disabled_reason" >&2
+      echo "  Use --dry-run for prompt inspection, or dispatch with --harness codex/cursor." >&2
+      return 2
+    fi
+  fi
 
   local repo_root title body slug branch wt prompt
   repo_root="$(git rev-parse --show-toplevel)" || return 1

.agents/test/dispatch_disabled_harness_test.sh

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+cd "$ROOT"
+
+# shellcheck source=/dev/null
+source "$ROOT/.agents/lib/dispatch.sh"
+
+issue_title() { echo "Disable agy harness smoke"; }
+issue_body() { echo "## Spec"; echo; echo "Smoke prompt body"; }
+get_field() { echo "Ready"; }
+set_stage() { echo "unexpected set_stage $*" >&2; return 99; }
+run_gate() { echo "unexpected run_gate $*" >&2; return 99; }
+
+unexpected_git_file="$(mktemp "${TMPDIR:-/tmp}/boxbox-agy-git.XXXX")"
+rm -f "$unexpected_git_file"
+git() {
+  if [ "${1:-}" = "rev-parse" ]; then
+    command git "$@"
+    return
+  fi
+  echo "unexpected git $*" >&2
+  touch "$unexpected_git_file"
+  return 99
+}
+
+set +e
+non_dry_output="$(dispatch 47 agy 2>&1)"
+non_dry_status=$?
+set -e
+
+[ "$non_dry_status" -eq 2 ] || {
+  echo "expected agy non-dry-run to exit 2, got $non_dry_status" >&2
+  echo "$non_dry_output" >&2
+  exit 1
+}
+[[ "$non_dry_output" == *"harness 'agy' is disabled"* ]] || {
+  echo "expected disabled-harness message" >&2
+  echo "$non_dry_output" >&2
+  exit 1
+}
+[ ! -e "$unexpected_git_file" ] || {
+  echo "agy non-dry-run reached git before failing" >&2
+  echo "$non_dry_output" >&2
+  exit 1
+}
+
+dry_output="$(dispatch 47 agy --dry-run 2>&1)"
+[[ "$dry_output" == *"[dry-run] no worktree / harness / PR / state change"* ]] || {
+  echo "expected agy dry-run to render dispatch preview" >&2
+  echo "$dry_output" >&2
+  exit 1
+}
+[[ "$dry_output" == *"Smoke prompt body"* ]] || {
+  echo "expected agy dry-run prompt body" >&2
+  echo "$dry_output" >&2
+  exit 1
+}

cmd/main.go

@@ -27,6 +27,7 @@ func main() {
 	ingestMeeting := flag.Int("ingest-meeting", 0, "Ingest meeting metadata and Race Hub datasets for all sessions")
 	ingestSession := flag.Int("ingest-session", 0, "Ingest Race Hub datasets for a session key")
 	ingestNews := flag.Bool("ingest-news", false, "Refresh RSS/Atom paddock briefing feeds")
+	prefetchTrackOutlines := flag.Int("prefetch-track-outlines", 0, "Warm the web track-outline cache for a season year (for web-only hosts, run before --web so /api/v1/track-outline can serve live maps)")
 	dryRun := flag.Bool("dry-run", false, "Preview ingestion without writing domain rows")
 	force := flag.Bool("force", false, "Re-ingest datasets even if already tracked in the session_coverage table as completed")
 	coverageYear := flag.Int("coverage", 0, "Show season coverage report for the given year")
@@ -76,11 +77,21 @@ func main() {
 	if *ingestNews {
 		ingestFlags++
 	}
+	if *prefetchTrackOutlines != 0 {
+		ingestFlags++
+	}
 	if ingestFlags > 0 {
 		if ingestFlags > 1 {
-			fmt.Fprintln(os.Stderr, "box-box: only one of --ingest-year, --backfill-season, --ingest-meeting, --ingest-session, or --ingest-news may be set")
+			fmt.Fprintln(os.Stderr, "box-box: only one of --ingest-year, --backfill-season, --ingest-meeting, --ingest-session, --ingest-news, or --prefetch-track-outlines may be set")
 			os.Exit(1)
 		}
+		if *prefetchTrackOutlines != 0 {
+			if err := runTrackOutlinePrefetch(client, *prefetchTrackOutlines); err != nil {
+				fmt.Fprintf(os.Stderr, "box-box track outline prefetch error: %v\n", err)
+				os.Exit(1)
+			}
+			return
+		}
 		if *ingestNews {
 			if err := runNewsIngestion(*dryRun, *dbPath); err != nil {
 				fmt.Fprintf(os.Stderr, "box-box ingest error: %v\n", err)
@@ -88,7 +99,7 @@ func main() {
 			}
 			return
 		}
-		
+
 		yearVal := *ingestYear
 		if *backfillSeason != 0 {
 			yearVal = *backfillSeason
@@ -174,6 +185,35 @@ func runIngestion(client *api.OpenF1Client, year, meetingKey, sessionKey int, fo
 	return err
 }
 
+func runTrackOutlinePrefetch(client *api.OpenF1Client, year int) error {
+	log.SetOutput(os.Stderr)
+
+	fmt.Fprintf(os.Stderr, "track outlines: warming HTTP cache %s for %d\n", api.DefaultCacheDBPath(), year)
+
+	meetings, err := client.GetMeetingsForYear(year)
+	if err != nil {
+		return fmt.Errorf("fetch meetings for %d: %w", year, err)
+	}
+
+	result := client.PrefetchTrackOutlinesForYear(year, meetings)
+	fmt.Printf(
+		"track outlines %d: cached %d/%d unique circuit(s) before, %d/%d after; %d skipped, %d fetched, %d failed\n",
+		result.Year,
+		result.CachedBefore,
+		result.UniqueCircuits,
+		result.CachedAfter,
+		result.UniqueCircuits,
+		result.Skipped,
+		result.Fetched,
+		result.Failed,
+	)
+
+	if result.CachedAfter == 0 {
+		return fmt.Errorf("cached zero track outlines for %d", year)
+	}
+	return nil
+}
+
 func runNewsIngestion(dryRun bool, dbPath string) error {
 	log.SetOutput(os.Stderr)
 
@@ -275,7 +315,7 @@ func runCoverageReport(year int, dbPath string) error {
 	}
 
 	fmt.Printf("\n--- Season %d Coverage Report ---\n\n", year)
-	fmt.Printf("%-35s | %-5s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s\n", 
+	fmt.Printf("%-35s | %-5s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s | %-2s\n",
 		"Meeting / Session (Key)", "ID", "DR", "SR", "SG", "ST", "PS", "PO", "RC", "WE", "LA")
 	fmt.Println(strings.Repeat("-", 82))
 

frontend/src/components/StrategyView.tsx

@@ -12,7 +12,7 @@ interface Props {
   hasStints: boolean
 }
 
-export function StrategyView({ results, stints, pit_stops: _pitStops, hasStints }: Props) {
+export function StrategyView({ results, stints, pit_stops, hasStints }: Props) {
   if (!hasStints) {
     return (
       <div>
@@ -88,6 +88,10 @@ export function StrategyView({ results, stints, pit_stops: _pitStops, hasStints
         lapEnd: s.lap_end,
         isNew: s.tyre_age_at_start === 0,
       })),
+    pitStops: pit_stops
+      .filter((p) => p.driver_number === driver.driver_number)
+      .map((p) => p.lap_number)
+      .sort((a, b) => a - b),
   }))
 
   return (

frontend/src/components/charts/TyreStintTimeline.tsx

@@ -12,6 +12,8 @@ export interface StintTimelineRow {
   label: string
   color: string
   stints: StintTimelineStint[]
+  /** Lap numbers where the driver pitted; optional — rows without stops render normally. */
+  pitStops?: number[]
 }
 
 interface TyreStintTimelineProps {
@@ -57,6 +59,14 @@ function stintBarW(stint: StintTimelineStint, totalLaps: number): number {
   return Math.max(2, (stintLength(stint) / totalLaps) * BAR_W)
 }
 
+function pitMarkerX(lapNumber: number, totalLaps: number): number {
+  return LEFT + ((lapNumber - 1) / totalLaps) * BAR_W
+}
+
+function pitMarkerTitle(driverLabel: string, lapNumber: number): string {
+  return `${driverLabel} pit stop · L${lapNumber}`
+}
+
 function axisTicks(totalLaps: number): number[] {
   const ticks: number[] = []
   for (let lap = 0; lap <= totalLaps; lap += 10) {
@@ -130,6 +140,21 @@ export function TyreStintTimeline({ rows, totalLaps }: TyreStintTimelineProps) {
                     <title>{stintTitle(stint)}</title>
                   </rect>
                 ))}
+
+                {(row.pitStops ?? []).map((lapNumber, pi) => (
+                  <line
+                    key={`pit-${pi}`}
+                    x1={pitMarkerX(lapNumber, safeTotal)}
+                    x2={pitMarkerX(lapNumber, safeTotal)}
+                    y1={BAR_Y - 3}
+                    y2={BAR_Y + BAR_H + 3}
+                    className="stint-timeline__pit-marker"
+                    data-testid="pit-marker"
+                    data-lap={lapNumber}
+                  >
+                    <title>{pitMarkerTitle(row.label, lapNumber)}</title>
+                  </line>
+                ))}
               </g>
             )
           })}

frontend/src/components/live/SessionBanner.tsx

@@ -5,18 +5,20 @@ import { WeatherStrip } from './WeatherStrip'
 
 interface Props {
   isLive: boolean
+  isArchive?: boolean
   snapshot: LiveStreamData
   rows: LiveTimingRow[]
   connection: 'connected' | 'connecting' | 'disconnected' | 'error'
   now: number
 }
 
-export function SessionBanner({ isLive, snapshot, rows, connection, now }: Props) {
+export function SessionBanner({ isLive, isArchive = false, snapshot, rows, connection, now }: Props) {
   const session = snapshot.Session
   const clock = extrapolateClock(snapshot.Clock, snapshot.ClockRefTime, snapshot.ClockExtrapolating, now)
   const display = liveSessionDisplay(session, rows)
   const atRiskLabel =
     display.atRiskStart && display.atRiskEnd ? `P${display.atRiskStart}-P${display.atRiskEnd} at risk` : ''
+  const stateLabel = isLive ? 'live' : isArchive ? 'archive' : 'stale'
 
   return (
     <section className="live-banner">
@@ -39,7 +41,7 @@ export function SessionBanner({ isLive, snapshot, rows, connection, now }: Props
             <span>
               L<strong>{snapshot.CurrentLap || '-'}</strong>/<strong>{snapshot.TotalLaps || '-'}</strong>
             </span>
-            <span className={isLive ? 'live-state live-state-on' : 'live-state'}>{isLive ? 'live' : 'stale'}</span>
+            <span className={isLive ? 'live-state live-state-on' : 'live-state'}>{stateLabel}</span>
           </div>
         </div>
       </div>

frontend/src/pages/LiveTimingPage.tsx

@@ -1,6 +1,6 @@
 import { useEffect, useMemo, useRef, useState } from 'react'
 import { useQuery } from '@tanstack/react-query'
-import { fetchLiveState, fetchLiveTrackOutline } from '../api'
+import { fetchLiveState } from '../api'
 import type { LivePosition, LiveStreamData } from '../types'
 import {
   loadPinnedDrivers,
@@ -25,14 +25,17 @@ import { PinnedDrivers } from '../components/live/PinnedDrivers'
 import { RaceControlFeed } from '../components/live/RaceControlFeed'
 import { EventRail } from '../components/live/EventRail'
 import { TeamRadioTicker } from '../components/live/TeamRadioTicker'
-import { TrackMap } from '../components/live/TrackMap'
 import { TyreDegPanel } from '../components/live/TyreDegPanel'
-import { Radio } from 'lucide-react'
+import { Archive, Radio } from 'lucide-react'
 
 type StreamStatus = 'connecting' | 'connected' | 'disconnected' | 'error'
 
 export function LiveTimingPage() {
-  const [snapshot, setSnapshot] = useState<LiveStreamData | null>(null)
+  const [activeSnapshot, setActiveSnapshot] = useState<LiveStreamData | null>(null)
+  const [archiveSnapshot, setArchiveSnapshot] = useState<LiveStreamData | null>(null)
+  const [archivePositions, setArchivePositions] = useState<Record<string, LivePosition>>({})
+  const [archiveSnapshotAt, setArchiveSnapshotAt] = useState<string | null>(null)
+  const [archiveMode, setArchiveMode] = useState(false)
   const [isLive, setIsLive] = useState(false)
   const [streamStatus, setStreamStatus] = useState<StreamStatus>('connecting')
   const [now, setNow] = useState(Date.now())
@@ -43,6 +46,10 @@ export function LiveTimingPage() {
   const [events, setEvents] = useState<LiveEvent[]>([])
   const prevSnapshotRef = useRef<LiveStreamData | null>(null)
   const sessionSigRef = useRef('')
+  const isLiveRef = useRef(false)
+  const archiveModeRef = useRef(false)
+  const snapshot = isLive ? activeSnapshot : archiveMode ? archiveSnapshot : null
+  const hasArchive = Boolean(archiveSnapshot)
 
   const { data, isLoading, isError, error } = useQuery({
     queryKey: ['live-state'],
@@ -50,24 +57,31 @@ export function LiveTimingPage() {
     staleTime: 5_000,
   })
 
-  const trackOutlineQuery = useQuery({
-    queryKey: [
-      'live-track-outline',
-      snapshot?.Session?.MeetingName ?? '',
-      snapshot?.Session?.CircuitName ?? '',
-    ],
-    queryFn: () => fetchLiveTrackOutline(snapshot!.Session),
-    enabled: Boolean(snapshot?.Session?.MeetingName || snapshot?.Session?.CircuitName),
-    staleTime: Infinity,
-    retry: false,
-  })
-
   useEffect(() => {
     if (!data) return
-    setIsLive(data.is_live)
+    const nextLive = data.is_live && Boolean(data.data)
-    setSnapshot(data.data)
+    setIsLive(nextLive)
+    isLiveRef.current = nextLive
+    if (nextLive && data.data) {
+      setActiveSnapshot(data.data)
+      setArchiveMode(false)
+      return
+    }
+
+    setActiveSnapshot(null)
+    setArchiveSnapshot(data.last_snapshot ?? null)
+    setArchivePositions(data.last_positions ?? {})
+    setArchiveSnapshotAt(data.last_snapshot_at ?? null)
+    setArchiveMode((current) => current && Boolean(data.last_snapshot))
   }, [data])
 
+  useEffect(() => {
+    archiveModeRef.current = archiveMode
+    if (archiveMode) {
+      setPositions(archivePositions)
+    }
+  }, [archiveMode, archivePositions])
+
   useEffect(() => {
     const timer = window.setInterval(() => setNow(Date.now()), 1000)
     return () => window.clearInterval(timer)
@@ -90,8 +104,23 @@ export function LiveTimingPage() {
     events.addEventListener('snapshot', (event) => {
       const state = parseLiveStateEvent(event.data)
       if (!state || cancelled) return
-      setIsLive(state.is_live)
+      const nextLive = state.is_live && Boolean(state.data)
-      setSnapshot(state.data)
+      setIsLive(nextLive)
+      if (nextLive && state.data) {
+        if (!isLiveRef.current || archiveModeRef.current) {
+          setPositions({})
+        }
+        isLiveRef.current = true
+        setActiveSnapshot(state.data)
+        setArchiveMode(false)
+      } else {
+        isLiveRef.current = false
+        setActiveSnapshot(null)
+        setArchiveSnapshot(state.last_snapshot ?? null)
+        setArchivePositions(state.last_positions ?? {})
+        setArchiveSnapshotAt(state.last_snapshot_at ?? null)
+        setArchiveMode((current) => current && Boolean(state.last_snapshot))
+      }
       setStreamStatus('connected')
     })
 
@@ -174,6 +203,19 @@ export function LiveTimingPage() {
     setPinned((prev) => togglePin(prev, racingNumber))
   }
 
+  const handleViewArchive = () => {
+    if (!archiveSnapshot) return
+    setIsLive(false)
+    setArchiveMode(true)
+    setPositions(archivePositions)
+  }
+
+  const archiveTimestamp = archiveSnapshotAt ? new Date(archiveSnapshotAt) : null
+  const archiveLabel =
+    archiveTimestamp && !Number.isNaN(archiveTimestamp.getTime())
+      ? `Archived snapshot from ${archiveTimestamp.toLocaleString()}`
+      : 'Archived live timing snapshot'
+
   return (
     <div className="page live-page" data-testid="live-page">
       {isError && (
@@ -182,12 +224,18 @@ export function LiveTimingPage() {
         </div>
       )}
 
-      {streamStatus === 'disconnected' && snapshot && (
+      {streamStatus === 'disconnected' && snapshot && !archiveMode && (
         <div className="live-status-strip live-status-warn">
           Stream disconnected — showing last received snapshot
         </div>
       )}
 
+      {archiveMode && snapshot && (
+        <div className="live-status-strip live-status-archive" data-testid="live-archive-strip">
+          {archiveLabel} — live updates are paused for this archive view
+        </div>
+      )}
+
       {isLoading && !snapshot && (
         <div className="loading-state">connecting to live timing…</div>
       )}
@@ -202,22 +250,27 @@ export function LiveTimingPage() {
           <p className="empty-state-desc" style={{ color: 'var(--text-2)' }}>
             The telemetry feed is currently offline. <br /><br /> Check the <a href="/" style={{ color: 'var(--red)', textDecoration: 'underline' }}>Command Center</a> for the weekend schedule or explore historical data in the <a href="/race-hub" style={{ color: 'var(--red)', textDecoration: 'underline' }}>Race Hub</a>.
           </p>
+          {hasArchive && (
+            <button type="button" className="live-archive-btn" onClick={handleViewArchive}>
+              <Archive size={15} />
+              View Last Session
+            </button>
+          )}
         </div>
       )}
 
       {snapshot && (
         <>
-          <SessionBanner isLive={isLive} snapshot={snapshot} rows={rows} connection={streamStatus} now={now} />
+          <SessionBanner
+            isLive={isLive}
+            isArchive={archiveMode}
+            snapshot={snapshot}
+            rows={rows}
+            connection={streamStatus}
+            now={now}
+          />
           <TrackStatusBanner status={snapshot.TrackStatus} />
           <PinnedDrivers rows={rows} history={gapHistory} pinned={pinned} onToggle={handleTogglePin} />
-          <TrackMap
-            outline={trackOutlineQuery.data}
-            positions={positions}
-            telemetry={snapshot.Telemetry}
-            drivers={snapshot.Drivers}
-            driverInfo={snapshot.DriverInfo}
-            loading={trackOutlineQuery.isLoading}
-          />
           <TyreDegPanel rows={rows} sessionType={snapshot.Session?.SessionType} pinned={pinned} />
           <div className="live-columns">
             <div className="live-tower-col">

frontend/src/styles/app.css

@@ -808,6 +808,12 @@ a { color: inherit; text-decoration: none; }
   color: var(--yellow);
 }
 
+.live-status-archive {
+  background: rgba(70, 140, 255, 0.08);
+  border: 1px solid rgba(70, 140, 255, 0.24);
+  color: #8bb7ff;
+}
+
 /* ── Live empty state ── */
 .live-empty-status {
   display: flex;
@@ -815,6 +821,29 @@ a { color: inherit; text-decoration: none; }
   margin-bottom: var(--s4);
 }
 
+.live-archive-btn {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  gap: var(--s2);
+  margin-top: var(--s5);
+  min-height: 36px;
+  padding: 0 var(--s4);
+  border: 1px solid rgba(255, 255, 255, 0.16);
+  border-radius: 4px;
+  background: rgba(255, 255, 255, 0.06);
+  color: var(--text);
+  font-family: var(--f-mono);
+  font-size: 11px;
+  font-weight: 800;
+  text-transform: uppercase;
+}
+
+.live-archive-btn:hover {
+  border-color: rgba(255, 255, 255, 0.28);
+  background: rgba(255, 255, 255, 0.1);
+}
+
 .mono { font-family: var(--f-mono); }
 
 .live-conn,

frontend/src/styles/stint-timeline.css

@@ -40,6 +40,13 @@
   stroke-dasharray: 2 1;
 }
 
+.stint-timeline__pit-marker {
+  stroke: var(--text);
+  stroke-width: 1.5;
+  opacity: 0.7;
+  pointer-events: stroke;
+}
+
 .stint-timeline__axis-tick {
   font-family: var(--f-mono);
   font-size: 9px;

frontend/src/test/CommandCenterPage.test.tsx

@@ -156,6 +156,7 @@ describe('CommandCenterPage', () => {
       race_control: [],
       weather: [],
       laps: [],
+      chapters: [],
     })
   })
 

frontend/src/test/LiveTimingPage.test.tsx

@@ -0,0 +1,166 @@
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+import { fireEvent, render, screen, waitFor } from '@testing-library/react'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { LiveTimingPage } from '../pages/LiveTimingPage'
+import type { LiveStateResponse, LiveStreamData } from '../types'
+
+vi.mock('../api', () => ({
+  fetchLiveState: vi.fn(),
+  fetchLiveTrackOutline: vi.fn(),
+}))
+
+import { fetchLiveState, fetchLiveTrackOutline } from '../api'
+
+const mockFetchLiveState = vi.mocked(fetchLiveState)
+const mockFetchLiveTrackOutline = vi.mocked(fetchLiveTrackOutline)
+
+class MockEventSource {
+  onopen: (() => void) | null = null
+  onerror: (() => void) | null = null
+
+  constructor() {
+    setTimeout(() => this.onopen?.(), 0)
+  }
+
+  addEventListener() {}
+  close() {}
+}
+
+const archivedSnapshot: LiveStreamData = {
+  Drivers: {
+    '1': {
+      RacingNumber: '1',
+      Position: 1,
+      PrevPosition: 1,
+      GapToLeader: '',
+      Interval: '',
+      LastLapTime: '1:21.345',
+      LastLapPB: false,
+      LastLapOB: false,
+      BestLapTime: '1:20.987',
+      BestLapPB: false,
+      BestLapOB: false,
+      BestLapNum: 22,
+      InPit: false,
+      PitOut: false,
+      Retired: false,
+      KnockedOut: false,
+      Cutoff: false,
+      OnFlyingLap: false,
+      NumberOfLaps: 30,
+      SpeedTrap: '',
+      Sectors: [],
+    },
+  },
+  DriverInfo: {
+    '1': {
+      RacingNumber: '1',
+      BroadcastName: 'M VERSTAPPEN',
+      Tla: 'VER',
+      TeamName: 'Red Bull Racing',
+      TeamColour: '3671C6',
+      FirstName: 'Max',
+      LastName: 'Verstappen',
+    },
+  },
+  Tyres: {
+    '1': { Compound: 'HARD', New: false, Age: 12 },
+  },
+  Telemetry: {},
+  RCMessages: [],
+  Weather: {
+    AirTemp: 22,
+    TrackTemp: 41,
+    Humidity: 58,
+    WindSpeed: 3,
+    WindDir: 180,
+    Rainfall: false,
+  },
+  Session: {
+    MeetingName: 'Testonia Grand Prix',
+    CircuitName: 'Testring',
+    SessionType: 'Race',
+    SessionName: 'Race',
+    Path: '',
+  },
+  TeamRadio: [],
+  SessionStatus: 'Finished',
+  TrackStatus: '1',
+  CurrentLap: 57,
+  TotalLaps: 57,
+  Clock: '',
+  ClockRefTime: '',
+  ClockExtrapolating: false,
+  Stints: {},
+}
+
+function renderPage(response: LiveStateResponse) {
+  const queryClient = new QueryClient({
+    defaultOptions: { queries: { retry: false } },
+  })
+  mockFetchLiveState.mockResolvedValue(response)
+  mockFetchLiveTrackOutline.mockResolvedValue({
+    circuit_key: 1,
+    points: [],
+    bounds: { minX: 0, maxX: 1, minY: 0, maxY: 1 },
+  })
+
+  return render(
+    <QueryClientProvider client={queryClient}>
+      <LiveTimingPage />
+    </QueryClientProvider>,
+  )
+}
+
+describe('LiveTimingPage archive mode', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    Object.defineProperty(window, 'EventSource', {
+      value: MockEventSource,
+      writable: true,
+      configurable: true,
+    })
+  })
+
+  it('keeps archived snapshots behind the View Last Session action', async () => {
+    renderPage({
+      is_live: false,
+      data: null,
+      last_snapshot: archivedSnapshot,
+      last_positions: {
+        '1': { x: 10, y: 20, z: 0, status: 'OnTrack' },
+      },
+      last_snapshot_at: '2026-07-04T14:00:00Z',
+    })
+
+    expect(await screen.findByTestId('live-empty')).toHaveTextContent('No live session active')
+    expect(screen.queryByText('Timing Tower')).not.toBeInTheDocument()
+
+    fireEvent.click(screen.getByRole('button', { name: /view last session/i }))
+
+    await waitFor(() => {
+      expect(screen.getByTestId('live-archive-strip')).toHaveTextContent('Archived snapshot')
+    })
+    expect(screen.getByText('Timing Tower')).toBeInTheDocument()
+    expect(screen.getAllByText('VER').length).toBeGreaterThan(0)
+    expect(screen.getByText('archive')).toBeInTheDocument()
+  })
+
+  it('does not show the archive action when no snapshot is retained', async () => {
+    renderPage({ is_live: false, data: null })
+
+    expect(await screen.findByTestId('live-empty')).toHaveTextContent('No live session active')
+    expect(screen.queryByRole('button', { name: /view last session/i })).not.toBeInTheDocument()
+  })
+
+  it('temporarily omits the track map while live GPS is unavailable', async () => {
+    renderPage({
+      is_live: true,
+      data: { ...archivedSnapshot, SessionStatus: 'Started' },
+    })
+
+    expect(await screen.findByText('Timing Tower')).toBeInTheDocument()
+    expect(screen.queryByText('Track Map')).not.toBeInTheDocument()
+    expect(mockFetchLiveTrackOutline).not.toHaveBeenCalled()
+  })
+})

frontend/src/test/RaceHubPage.test.tsx

@@ -155,6 +155,7 @@ const raceHub: RaceHub = {
       is_pit_out_lap: false,
     },
   ],
+  chapters: [],
 }
 
 const weekend: Weekend = {

frontend/src/test/StrategyView.test.tsx

@@ -106,6 +106,17 @@ describe('StrategyView — stints available', () => {
     )
     expect(screen.queryByText(/Stints not available/i)).not.toBeInTheDocument()
   })
+
+  it('maps pit_stops into timeline pit markers for the matching driver', () => {
+    const { container } = render(
+      <StrategyView results={results} stints={stints} pit_stops={pitStops} hasStints={true} />
+    )
+    const markers = container.querySelectorAll('[data-testid="pit-marker"]')
+    expect(markers).toHaveLength(1)
+    expect(markers[0]).toHaveAttribute('data-lap', '19')
+    const titles = [...container.querySelectorAll('title')].map((t) => t.textContent)
+    expect(titles).toContain('HAM pit stop · L19')
+  })
 })
 
 describe('StrategyView — stints missing', () => {

frontend/src/test/live.test.ts

@@ -163,6 +163,20 @@ describe('live transforms', () => {
     expect(parsed?.data?.Drivers['16'].RacingNumber).toBe('16')
   })
 
+  it('parses archived EventSource snapshots separately from active data', () => {
+    const parsed = parseLiveStateEvent(JSON.stringify({
+      is_live: false,
+      data: null,
+      last_snapshot: snapshot,
+      last_positions: { '16': { x: 1, y: 2, z: 3, status: 'OnTrack' } },
+      last_snapshot_at: '2026-07-04T14:00:00Z',
+    }))
+    expect(parsed?.is_live).toBe(false)
+    expect(parsed?.data).toBeNull()
+    expect(parsed?.last_snapshot?.Drivers['16'].RacingNumber).toBe('16')
+    expect(parsed?.last_positions?.['16'].status).toBe('OnTrack')
+  })
+
   it('sorts timing rows by live position and includes drivers with metadata only', () => {
     const rows = sortLiveTimingRows(snapshot)
     expect(rows.map((row) => row.RacingNumber)).toEqual(['16', '1', '44'])

frontend/src/test/tyre-stint-timeline.test.tsx

@@ -71,6 +71,61 @@ describe('TyreStintTimeline', () => {
     expect(screen.getByTestId('stint-timeline-empty')).toBeInTheDocument()
     expect(screen.getByText(/No stint data/i)).toBeInTheDocument()
   })
+
+  it('renders one pit marker per stop at the correct lap position', () => {
+    const rowsWithPits: StintTimelineRow[] = [
+      {
+        label: 'HAM',
+        color: '#E8002D',
+        stints: [{ compound: 'SOFT', lapStart: 1, lapEnd: 18 }],
+        pitStops: [19],
+      },
+      {
+        label: 'VER',
+        color: '#3671C6',
+        stints: [
+          { compound: 'MEDIUM', lapStart: 1, lapEnd: 30 },
+          { compound: 'SOFT', lapStart: 31, lapEnd: 78 },
+        ],
+        pitStops: [31, 52],
+      },
+    ]
+    const { container } = render(
+      <TyreStintTimeline rows={rowsWithPits} totalLaps={78} />,
+    )
+    const markers = container.querySelectorAll('[data-testid="pit-marker"]')
+    expect(markers).toHaveLength(3)
+    expect(markers[0]).toHaveAttribute('data-lap', '19')
+    expect(markers[1]).toHaveAttribute('data-lap', '31')
+    expect(markers[2]).toHaveAttribute('data-lap', '52')
+    expect(container.querySelectorAll('.stint-timeline__bar')).toHaveLength(3)
+  })
+
+  it('positions pit markers using lap_number and includes driver in tooltip', () => {
+    const rows: StintTimelineRow[] = [
+      {
+        label: 'HAM',
+        color: '#E8002D',
+        stints: [{ compound: 'SOFT', lapStart: 1, lapEnd: 18 }],
+        pitStops: [19],
+      },
+    ]
+    const { container } = render(<TyreStintTimeline rows={rows} totalLaps={78} />)
+    const marker = container.querySelector('[data-testid="pit-marker"]') as SVGLineElement
+    expect(marker).toBeTruthy()
+    // lap 19 → x = 48 + (18/78) * 580 ≈ 181.85
+    expect(Number(marker.getAttribute('x1'))).toBeCloseTo(181.85, 1)
+    const titles = [...container.querySelectorAll('title')].map((t) => t.textContent)
+    expect(titles).toContain('HAM pit stop · L19')
+  })
+
+  it('leaves rows without pit data unchanged', () => {
+    const { container } = render(
+      <TyreStintTimeline rows={sampleRows} totalLaps={78} />,
+    )
+    expect(container.querySelectorAll('[data-testid="pit-marker"]')).toHaveLength(0)
+    expect(container.querySelectorAll('.stint-timeline__bar')).toHaveLength(3)
+  })
 })
 
 const results: EnrichedResult[] = [

frontend/src/types.ts

@@ -89,6 +89,17 @@ export interface RaceHub {
   race_control: RaceControlMessage[]
   weather: WeatherSample[]
   laps: Lap[]
+  chapters: Chapter[]
+}
+
+export interface Chapter {
+  kind: 'start' | 'safety_car' | 'virtual_safety_car' | 'red_flag' | 'pit_phase' | 'decisive_swing' | 'finish' | string
+  title: string
+  start_lap: number
+  end_lap: number
+  start_time?: string
+  end_time?: string
+  driver_numbers: number[]
 }
 
 export interface Stint {
@@ -206,6 +217,9 @@ export interface Weekend {
 export interface LiveStateResponse {
   is_live: boolean
   data: LiveStreamData | null
+  last_snapshot?: LiveStreamData | null
+  last_positions?: Record<string, LivePosition> | null
+  last_snapshot_at?: string
 }
 
 export interface LivePosition {
@@ -316,6 +330,7 @@ export interface LiveStreamData {
   Weather: LiveWeatherData
   Session: LiveSessionMeta
   TeamRadio: LiveRadioCapture[]
+  SessionStatus?: string
   TrackStatus: string
   CurrentLap: number
   TotalLaps: number

internal/api/cache.go

@@ -94,6 +94,12 @@ func cacheDBPath() string {
 	return filepath.Join(".cache", "box-box", "cache.db")
 }
 
+// DefaultCacheDBPath returns the HTTP cache database path used by the OpenF1
+// client in both TUI and web modes.
+func DefaultCacheDBPath() string {
+	return cacheDBPath()
+}
+
 // ttlForURL determines the appropriate TTL based on the URL pattern.
 // Returns 0 (CacheTTLForever) for historical data that will never change.
 func ttlForURL(url string) time.Duration {

internal/api/openf1.go

@@ -623,6 +623,19 @@ func (c *OpenF1Client) GetTeamRadio(sessionKey, driverNumber int) ([]models.Team
 // to maximise the chance of finding data quickly.
 var candidateDrivers = []int{1, 11, 44, 16, 55, 4, 14, 63, 81, 24}
 
+// TrackOutlinePrefetchResult summarizes a season track-outline cache warming
+// run. Counts are scoped to the unique non-zero circuit keys in the provided
+// meeting list.
+type TrackOutlinePrefetchResult struct {
+	Year           int
+	UniqueCircuits int
+	CachedBefore   int
+	CachedAfter    int
+	Skipped        int
+	Fetched        int
+	Failed         int
+}
+
 // PrefetchTrackOutlines fetches GPS location data for every circuit in the
 // provided meeting list and stores it in the cache so the track map tab can
 // render during live sessions when the free-tier API is locked.
@@ -632,28 +645,58 @@ var candidateDrivers = []int{1, 11, 44, 16, 55, 4, 14, 63, 81, 24}
 // Errors per-circuit are silently ignored — this is a best-effort operation
 // and must never block or crash the main UI.
 func (c *OpenF1Client) PrefetchTrackOutlines(meetings []models.Meeting) {
+	year := time.Now().Year()
+	for _, m := range meetings {
+		if m.Year != 0 {
+			year = m.Year
+			break
+		}
+	}
+	_ = c.PrefetchTrackOutlinesForYear(year, meetings)
+}
+
+// PrefetchTrackOutlinesForYear fetches and caches track outlines for unique
+// circuits in the provided meeting list, storing them under the explicit season
+// year. Unlike PrefetchTrackOutlines, it returns accounting suitable for CLI
+// cache-warming workflows.
+func (c *OpenF1Client) PrefetchTrackOutlinesForYear(year int, meetings []models.Meeting) TrackOutlinePrefetchResult {
 	const maxWorkers = 3
 
-	year := time.Now().Year()
+	result := TrackOutlinePrefetchResult{Year: year}
-
+	uniqueByCircuit := make(map[int]models.Meeting)
-	// Filter to meetings that need fetching.
+	var unique []models.Meeting
-	var pending []models.Meeting
 	for _, m := range meetings {
 		if m.CircuitKey == 0 {
 			continue
 		}
+		if _, exists := uniqueByCircuit[m.CircuitKey]; exists {
+			continue
+		}
+		uniqueByCircuit[m.CircuitKey] = m
+		unique = append(unique, m)
+	}
+
+	result.UniqueCircuits = len(unique)
+
+	// Filter to meetings that need fetching.
+	var pending []models.Meeting
+	for _, m := range unique {
 		if _, ok := c.cache.GetTrackOutline(m.CircuitKey, year); ok {
+			result.CachedBefore++
+			result.Skipped++
 			continue // already cached for this season
 		}
 		pending = append(pending, m)
 	}
 
 	if len(pending) == 0 {
-		return
+		result.CachedAfter = result.CachedBefore
+		return result
 	}
 
 	sem := make(chan struct{}, maxWorkers)
 	var wg sync.WaitGroup
+	var mu sync.Mutex
 
 	for _, mtg := range pending {
 		mtg := mtg // capture
@@ -662,19 +705,34 @@ func (c *OpenF1Client) PrefetchTrackOutlines(meetings []models.Meeting) {
 		go func() {
 			defer wg.Done()
 			defer func() { <-sem }()
-			c.prefetchCircuit(mtg, year)
+			ok := c.prefetchCircuit(mtg, year)
+			mu.Lock()
+			if ok {
+				result.Fetched++
+			} else {
+				result.Failed++
+			}
+			mu.Unlock()
 		}()
 	}
 
 	wg.Wait()
+
+	for _, m := range unique {
+		if _, ok := c.cache.GetTrackOutline(m.CircuitKey, year); ok {
+			result.CachedAfter++
+		}
+	}
+
+	return result
 }
 
 // prefetchCircuit fetches the track outline for a single meeting and stores it.
 // It prefers completed sessions (past date_end) so the data is full and stable.
-func (c *OpenF1Client) prefetchCircuit(mtg models.Meeting, year int) {
+func (c *OpenF1Client) prefetchCircuit(mtg models.Meeting, year int) bool {
 	sessions, err := c.GetSessionsForMeeting(int(mtg.MeetingKey))
 	if err != nil || len(sessions) == 0 {
-		return
+		return false
 	}
 
 	// Pick the best session: prefer a completed race, then any session with
@@ -696,7 +754,7 @@ func (c *OpenF1Client) prefetchCircuit(mtg models.Meeting, year int) {
 		}
 	}
 	if bestSession == nil {
-		return
+		return false
 	}
 
 	// Try candidate drivers in order until we find one with enough points.
@@ -706,7 +764,7 @@ func (c *OpenF1Client) prefetchCircuit(mtg models.Meeting, year int) {
 			continue
 		}
 		// Store under the circuit key for this year and stop.
-		_ = c.cache.SetTrackOutline(mtg.CircuitKey, year, locs)
+		return c.cache.SetTrackOutline(mtg.CircuitKey, year, locs) == nil
-		return
 	}
+	return false
 }

internal/api/track_outline_prefetch_test.go

@@ -0,0 +1,109 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+	"time"
+
+	"github.com/AmanTahiliani/box-box/internal/models"
+)
+
+func newTrackOutlineTestClient(t *testing.T, srvURL string) *OpenF1Client {
+	t.Helper()
+	t.Setenv("HOME", t.TempDir())
+	t.Setenv("XDG_CACHE_HOME", t.TempDir())
+
+	c := NewOpenF1Client(srvURL, 5*time.Second)
+	c.pacer = &requestPacer{}
+	t.Cleanup(func() { _ = c.Close() })
+	return c
+}
+
+func TestPrefetchTrackOutlinesForYearSkipsCachedAndWritesLocations(t *testing.T) {
+	var sessionsByMeeting = map[string][]models.Session{
+		"202": {
+			{
+				SessionKey:  9002,
+				SessionName: "Race",
+				MeetingKey:  202,
+				CircuitKey:  2,
+				DateEnd:     "2026-01-01T12:00:00+00:00",
+			},
+		},
+	}
+	var sessionsRequested []string
+	var locationsRequested []string
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/v1/sessions":
+			meetingKey := r.URL.Query().Get("meeting_key")
+			sessionsRequested = append(sessionsRequested, meetingKey)
+			_ = json.NewEncoder(w).Encode(sessionsByMeeting[meetingKey])
+		case "/v1/location":
+			sessionKey := r.URL.Query().Get("session_key")
+			driverNumber := r.URL.Query().Get("driver_number")
+			locationsRequested = append(locationsRequested, sessionKey+"/"+driverNumber)
+			_ = json.NewEncoder(w).Encode(testLocations(9002, 1, 51))
+		default:
+			t.Fatalf("unexpected request path %s", r.URL.Path)
+		}
+	}))
+	defer srv.Close()
+
+	client := newTrackOutlineTestClient(t, srv.URL)
+	if err := client.Cache().SetTrackOutline(1, 2026, testLocations(9001, 1, 51)); err != nil {
+		t.Fatalf("SetTrackOutline() error = %v", err)
+	}
+
+	result := client.PrefetchTrackOutlinesForYear(2026, []models.Meeting{
+		{MeetingKey: 101, Year: 2026, Circuit: models.Circuit{CircuitKey: 1}},
+		{MeetingKey: 202, Year: 2026, Circuit: models.Circuit{CircuitKey: 2}},
+		{MeetingKey: 303, Year: 2026, Circuit: models.Circuit{CircuitKey: 2}},
+	})
+
+	if result.UniqueCircuits != 2 {
+		t.Fatalf("UniqueCircuits = %d, want 2", result.UniqueCircuits)
+	}
+	if result.CachedBefore != 1 || result.Skipped != 1 || result.Fetched != 1 || result.Failed != 0 || result.CachedAfter != 2 {
+		t.Fatalf("unexpected result: %+v", result)
+	}
+	if got, want := len(sessionsRequested), 1; got != want {
+		t.Fatalf("sessions requested %d time(s), want %d: %v", got, want, sessionsRequested)
+	}
+	if sessionsRequested[0] != "202" {
+		t.Fatalf("requested meeting %s, want 202", sessionsRequested[0])
+	}
+	if got, want := len(locationsRequested), 1; got != want {
+		t.Fatalf("locations requested %d time(s), want %d: %v", got, want, locationsRequested)
+	}
+	if locationsRequested[0] != "9002/1" {
+		t.Fatalf("requested location %s, want 9002/1", locationsRequested[0])
+	}
+
+	locs, ok := client.Cache().GetTrackOutline(2, 2026)
+	if !ok {
+		t.Fatal("expected circuit 2 outline to be cached")
+	}
+	if len(locs) != 51 {
+		t.Fatalf("cached %d locations, want 51", len(locs))
+	}
+}
+
+func testLocations(sessionKey, driverNumber, count int) []models.Location {
+	locs := make([]models.Location, count)
+	for i := range locs {
+		locs[i] = models.Location{
+			Date:         "2026-01-01T12:00:" + strconv.Itoa(i%60) + "+00:00",
+			DriverNumber: driverNumber,
+			MeetingKey:   202,
+			SessionKey:   sessionKey,
+			X:            float64(i),
+			Y:            float64(i * 2),
+		}
+	}
+	return locs
+}

internal/chapters/chapters.go

@@ -0,0 +1,628 @@
+package chapters
+
+import (
+	"fmt"
+	"math"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/AmanTahiliani/box-box/internal/models"
+)
+
+const (
+	KindStart            = "start"
+	KindSafetyCar        = "safety_car"
+	KindVirtualSafetyCar = "virtual_safety_car"
+	KindRedFlag          = "red_flag"
+	KindPitPhase         = "pit_phase"
+	KindDecisiveSwing    = "decisive_swing"
+	KindFinish           = "finish"
+
+	pitPhaseWindowLaps = 3
+	pitPhaseShare      = 0.30
+	minPitPhaseStops   = 2
+	maxDecisiveSwings  = 3
+	decisiveAfterLap   = 5
+	structuralPriority = 110
+	flagPriority       = 100
+	pitPhasePriority   = 50
+	decisivePriority   = 40
+)
+
+type RaceControl = models.RaceControl
+type PositionSample = models.Position
+type Lap = models.Lap
+
+// Chapter is a deterministic replay segment derived from timing and race-control data.
+type Chapter struct {
+	Kind          string `json:"kind"`
+	Title         string `json:"title"`
+	StartLap      int    `json:"start_lap"`
+	EndLap        int    `json:"end_lap"`
+	StartTime     string `json:"start_time,omitempty"`
+	EndTime       string `json:"end_time,omitempty"`
+	DriverNumbers []int  `json:"driver_numbers"`
+}
+
+// Detect builds replay chapters from already-loaded race-hub datasets.
+func Detect(rc []RaceControl, positions []PositionSample, laps []Lap, totalLaps int) []Chapter {
+	totalLaps = normalizeTotalLaps(totalLaps, laps, rc)
+	if totalLaps <= 0 && len(rc) == 0 && len(positions) == 0 && len(laps) == 0 {
+		return []Chapter{}
+	}
+	if totalLaps <= 0 {
+		totalLaps = 1
+	}
+
+	lapIndex := buildLapIndex(laps)
+	chapters := []Chapter{
+		{
+			Kind:      KindStart,
+			Title:     "Start",
+			StartLap:  1,
+			EndLap:    minInt(1, totalLaps),
+			StartTime: lapIndex.lapStart(1),
+			EndTime:   lapIndex.lapEnd(1),
+		},
+	}
+	chapters = append(chapters, detectFlagPeriods(rc, lapIndex, totalLaps)...)
+	chapters = append(chapters, detectPitPhases(laps, lapIndex)...)
+	chapters = append(chapters, detectDecisiveSwings(positions, lapIndex, totalLaps)...)
+	chapters = append(chapters, detectFinish(rc, lapIndex, totalLaps))
+
+	return resolveConflicts(chapters)
+}
+
+func normalizeTotalLaps(totalLaps int, laps []Lap, rc []RaceControl) int {
+	for _, l := range laps {
+		if l.LapNumber > totalLaps {
+			totalLaps = l.LapNumber
+		}
+	}
+	for _, msg := range rc {
+		if msg.LapNumber != nil && *msg.LapNumber > totalLaps {
+			totalLaps = *msg.LapNumber
+		}
+	}
+	return totalLaps
+}
+
+type lapIndex struct {
+	byLap  map[int]string
+	events []lapEvent
+}
+
+type lapEvent struct {
+	lap int
+	at  time.Time
+}
+
+func buildLapIndex(laps []Lap) lapIndex {
+	idx := lapIndex{byLap: map[int]string{}}
+	for _, l := range laps {
+		if l.LapNumber <= 0 || l.DateStart == "" {
+			continue
+		}
+		if _, ok := idx.byLap[l.LapNumber]; !ok {
+			idx.byLap[l.LapNumber] = l.DateStart
+		}
+		at, ok := parseTime(l.DateStart)
+		if ok {
+			idx.events = append(idx.events, lapEvent{lap: l.LapNumber, at: at})
+		}
+	}
+	sort.Slice(idx.events, func(i, j int) bool {
+		if idx.events[i].at.Equal(idx.events[j].at) {
+			return idx.events[i].lap < idx.events[j].lap
+		}
+		return idx.events[i].at.Before(idx.events[j].at)
+	})
+	return idx
+}
+
+func (idx lapIndex) lapStart(lap int) string {
+	return idx.byLap[lap]
+}
+
+func (idx lapIndex) lapEnd(lap int) string {
+	if v := idx.byLap[lap+1]; v != "" {
+		return v
+	}
+	return idx.byLap[lap]
+}
+
+func (idx lapIndex) lapForTime(raw string) int {
+	at, ok := parseTime(raw)
+	if !ok || len(idx.events) == 0 {
+		return 0
+	}
+	lap := 0
+	for _, event := range idx.events {
+		if event.at.After(at) {
+			break
+		}
+		lap = event.lap
+	}
+	if lap == 0 {
+		return idx.events[0].lap
+	}
+	return lap
+}
+
+type flagState struct {
+	startLap  int
+	startTime string
+}
+
+func detectFlagPeriods(rc []RaceControl, idx lapIndex, totalLaps int) []Chapter {
+	var chapters []Chapter
+	active := map[string]flagState{}
+	for _, msg := range rc {
+		kind, ok := flagKind(msg)
+		if !ok && greenFlagClear(msg) {
+			for activeKind, st := range active {
+				lap := messageLap(msg, idx)
+				if lap <= 0 {
+					lap = st.startLap
+				}
+				endLap := clampLap(lap, st.startLap, totalLaps)
+				chapters = append(chapters, Chapter{
+					Kind:      activeKind,
+					Title:     flagTitle(activeKind, st.startLap, endLap),
+					StartLap:  st.startLap,
+					EndLap:    endLap,
+					StartTime: st.startTime,
+					EndTime:   firstNonEmpty(msg.Date, idx.lapEnd(endLap)),
+				})
+				delete(active, activeKind)
+			}
+			continue
+		}
+		if !ok {
+			continue
+		}
+		lap := messageLap(msg, idx)
+		if lap <= 0 {
+			lap = 1
+		}
+		if flagCleared(msg) {
+			st, ok := active[kind]
+			if !ok {
+				continue
+			}
+			endLap := clampLap(lap, st.startLap, totalLaps)
+			chapters = append(chapters, Chapter{
+				Kind:      kind,
+				Title:     flagTitle(kind, st.startLap, endLap),
+				StartLap:  st.startLap,
+				EndLap:    endLap,
+				StartTime: st.startTime,
+				EndTime:   firstNonEmpty(msg.Date, idx.lapEnd(endLap)),
+			})
+			delete(active, kind)
+			continue
+		}
+		if flagStarted(msg) {
+			active[kind] = flagState{
+				startLap:  clampLap(lap, 1, totalLaps),
+				startTime: firstNonEmpty(msg.Date, idx.lapStart(lap)),
+			}
+		}
+	}
+	for kind, st := range active {
+		endLap := totalLaps
+		chapters = append(chapters, Chapter{
+			Kind:      kind,
+			Title:     flagTitle(kind, st.startLap, endLap),
+			StartLap:  st.startLap,
+			EndLap:    endLap,
+			StartTime: st.startTime,
+			EndTime:   idx.lapEnd(endLap),
+		})
+	}
+	return chapters
+}
+
+func flagKind(msg RaceControl) (string, bool) {
+	text := upperText(string(msg.Category), string(msg.Flag), msg.Message)
+	if strings.Contains(text, "VSC") || strings.Contains(text, "VIRTUAL SAFETY CAR") {
+		return KindVirtualSafetyCar, true
+	}
+	if strings.Contains(text, "RED FLAG") || string(msg.Flag) == string(models.FlagRed) {
+		return KindRedFlag, true
+	}
+	if strings.Contains(text, "SAFETY CAR") || msg.Category == models.CategorySafetyCar {
+		return KindSafetyCar, true
+	}
+	return "", false
+}
+
+func flagStarted(msg RaceControl) bool {
+	text := upperText(string(msg.Category), string(msg.Flag), msg.Message)
+	if strings.Contains(text, "CLEAR") || strings.Contains(text, "ENDING") || strings.Contains(text, "IN THIS LAP") || strings.Contains(text, "GREEN") {
+		return false
+	}
+	return strings.Contains(text, "DEPLOY") ||
+		strings.Contains(text, "RED FLAG") ||
+		strings.Contains(text, "VIRTUAL SAFETY CAR") ||
+		strings.Contains(text, "VSC") ||
+		strings.Contains(text, "SAFETY CAR") ||
+		string(msg.Flag) == string(models.FlagRed)
+}
+
+func flagCleared(msg RaceControl) bool {
+	text := upperText(string(msg.Category), string(msg.Flag), msg.Message)
+	return strings.Contains(text, "CLEAR") ||
+		strings.Contains(text, "ENDING") ||
+		strings.Contains(text, "IN THIS LAP") ||
+		strings.Contains(text, "GREEN")
+}
+
+func greenFlagClear(msg RaceControl) bool {
+	text := upperText(string(msg.Flag), msg.Message)
+	return strings.Contains(text, "GREEN")
+}
+
+func flagTitle(kind string, startLap, endLap int) string {
+	name := "Flag period"
+	switch kind {
+	case KindSafetyCar:
+		name = "Safety Car"
+	case KindVirtualSafetyCar:
+		name = "Virtual Safety Car"
+	case KindRedFlag:
+		name = "Red Flag"
+	}
+	return fmt.Sprintf("%s (L%d-L%d)", name, startLap, endLap)
+}
+
+func detectPitPhases(laps []Lap, idx lapIndex) []Chapter {
+	type pitOut struct {
+		lap    int
+		driver int
+	}
+	var stops []pitOut
+	for _, l := range laps {
+		if l.IsPitOutLap && l.LapNumber > 0 {
+			stops = append(stops, pitOut{lap: l.LapNumber, driver: l.DriverNumber})
+		}
+	}
+	if len(stops) < minPitPhaseStops {
+		return nil
+	}
+	sort.Slice(stops, func(i, j int) bool {
+		if stops[i].lap == stops[j].lap {
+			return stops[i].driver < stops[j].driver
+		}
+		return stops[i].lap < stops[j].lap
+	})
+	needed := int(math.Ceil(float64(len(stops)) * pitPhaseShare))
+	if needed < minPitPhaseStops {
+		needed = minPitPhaseStops
+	}
+
+	var windows []Chapter
+	for i := 0; i < len(stops); i++ {
+		start := stops[i].lap
+		end := start + pitPhaseWindowLaps - 1
+		drivers := map[int]bool{}
+		count := 0
+		for _, stop := range stops {
+			if stop.lap < start || stop.lap > end {
+				continue
+			}
+			count++
+			drivers[stop.driver] = true
+		}
+		if count < needed {
+			continue
+		}
+		ch := Chapter{
+			Kind:          KindPitPhase,
+			Title:         fmt.Sprintf("Pit phase (L%d-L%d)", start, end),
+			StartLap:      start,
+			EndLap:        end,
+			StartTime:     idx.lapStart(start),
+			EndTime:       idx.lapEnd(end),
+			DriverNumbers: sortedDriverNumbers(drivers),
+		}
+		if len(windows) > 0 && ch.StartLap <= windows[len(windows)-1].EndLap+1 {
+			last := &windows[len(windows)-1]
+			if ch.EndLap > last.EndLap {
+				last.EndLap = ch.EndLap
+				last.EndTime = idx.lapEnd(last.EndLap)
+			}
+			drivers := sliceToSet(last.DriverNumbers)
+			for _, driver := range ch.DriverNumbers {
+				drivers[driver] = true
+			}
+			last.DriverNumbers = sortedDriverNumbers(drivers)
+			last.Title = fmt.Sprintf("Pit phase (L%d-L%d)", last.StartLap, last.EndLap)
+			continue
+		}
+		windows = append(windows, ch)
+	}
+	return windows
+}
+
+type swingCandidate struct {
+	chapter      Chapter
+	significance int
+}
+
+func detectDecisiveSwings(positions []PositionSample, idx lapIndex, totalLaps int) []Chapter {
+	if len(positions) == 0 || len(idx.events) == 0 || totalLaps <= decisiveAfterLap {
+		return nil
+	}
+	snapshots := buildPositionSnapshots(positions, idx, totalLaps)
+	if len(snapshots) == 0 {
+		return nil
+	}
+	final := snapshots[totalLaps]
+	if len(final) == 0 {
+		for lap := totalLaps - 1; lap >= 1; lap-- {
+			if len(snapshots[lap]) > 0 {
+				final = snapshots[lap]
+				break
+			}
+		}
+	}
+	var candidates []swingCandidate
+	seenDriver := map[int]bool{}
+	for lap := decisiveAfterLap + 1; lap <= totalLaps; lap++ {
+		prev := snapshots[lap-1]
+		curr := snapshots[lap]
+		if len(prev) == 0 || len(curr) == 0 {
+			continue
+		}
+		for driver, pos := range curr {
+			prevPos, ok := prev[driver]
+			if !ok || prevPos <= pos || pos > 5 || pos <= 0 || seenDriver[driver] {
+				continue
+			}
+			finalPos, ok := final[driver]
+			if !ok || finalPos > pos {
+				continue
+			}
+			overtaken := driverAtPosition(curr, prevPos, driver)
+			drivers := []int{driver}
+			if overtaken != 0 {
+				drivers = append(drivers, overtaken)
+			}
+			candidates = append(candidates, swingCandidate{
+				chapter: Chapter{
+					Kind:          KindDecisiveSwing,
+					Title:         fmt.Sprintf("Decisive swing: #%d to P%d (L%d)", driver, pos, lap),
+					StartLap:      lap,
+					EndLap:        lap,
+					StartTime:     idx.lapStart(lap),
+					EndTime:       idx.lapEnd(lap),
+					DriverNumbers: drivers,
+				},
+				significance: (prevPos-pos)*10 + (6 - pos),
+			})
+			seenDriver[driver] = true
+		}
+	}
+	sort.Slice(candidates, func(i, j int) bool {
+		if candidates[i].significance == candidates[j].significance {
+			return candidates[i].chapter.StartLap < candidates[j].chapter.StartLap
+		}
+		return candidates[i].significance > candidates[j].significance
+	})
+	if len(candidates) > maxDecisiveSwings {
+		candidates = candidates[:maxDecisiveSwings]
+	}
+	out := make([]Chapter, 0, len(candidates))
+	for _, c := range candidates {
+		out = append(out, c.chapter)
+	}
+	return out
+}
+
+func buildPositionSnapshots(positions []PositionSample, idx lapIndex, totalLaps int) map[int]map[int]int {
+	byLap := map[int][]PositionSample{}
+	for _, p := range positions {
+		if p.Position <= 0 {
+			continue
+		}
+		lap := idx.lapForTime(p.Date)
+		if lap <= 0 || lap > totalLaps {
+			continue
+		}
+		byLap[lap] = append(byLap[lap], p)
+	}
+	last := map[int]int{}
+	snapshots := map[int]map[int]int{}
+	for lap := 1; lap <= totalLaps; lap++ {
+		for _, p := range byLap[lap] {
+			last[p.DriverNumber] = p.Position
+		}
+		if len(last) == 0 {
+			continue
+		}
+		cp := make(map[int]int, len(last))
+		for driver, pos := range last {
+			cp[driver] = pos
+		}
+		snapshots[lap] = cp
+	}
+	return snapshots
+}
+
+func driverAtPosition(snapshot map[int]int, pos int, exclude int) int {
+	for driver, driverPos := range snapshot {
+		if driver != exclude && driverPos == pos {
+			return driver
+		}
+	}
+	return 0
+}
+
+func detectFinish(rc []RaceControl, idx lapIndex, totalLaps int) Chapter {
+	finishLap := totalLaps
+	finishTime := idx.lapEnd(totalLaps)
+	for _, msg := range rc {
+		text := upperText(string(msg.Flag), msg.Message)
+		if strings.Contains(text, "CHEQUER") || string(msg.Flag) == string(models.FlagChequered) {
+			if lap := messageLap(msg, idx); lap > 0 {
+				finishLap = lap
+			}
+			finishTime = firstNonEmpty(msg.Date, finishTime)
+		}
+	}
+	startLap := finishLap - 1
+	if startLap < 1 {
+		startLap = 1
+	}
+	return Chapter{
+		Kind:      KindFinish,
+		Title:     fmt.Sprintf("Finish (L%d-L%d)", startLap, finishLap),
+		StartLap:  startLap,
+		EndLap:    finishLap,
+		StartTime: idx.lapStart(startLap),
+		EndTime:   finishTime,
+	}
+}
+
+func resolveConflicts(chapters []Chapter) []Chapter {
+	normalized := make([]Chapter, 0, len(chapters))
+	for _, ch := range chapters {
+		if ch.StartLap <= 0 {
+			ch.StartLap = 1
+		}
+		if ch.EndLap <= 0 {
+			ch.EndLap = ch.StartLap
+		}
+		if ch.EndLap < ch.StartLap {
+			ch.EndLap = ch.StartLap
+		}
+		if ch.DriverNumbers == nil {
+			ch.DriverNumbers = []int{}
+		}
+		normalized = append(normalized, ch)
+	}
+	sort.SliceStable(normalized, func(i, j int) bool {
+		if normalized[i].StartLap == normalized[j].StartLap {
+			return priority(normalized[i].Kind) > priority(normalized[j].Kind)
+		}
+		return normalized[i].StartLap < normalized[j].StartLap
+	})
+
+	out := make([]Chapter, 0, len(normalized))
+	for _, ch := range normalized {
+		if len(out) == 0 {
+			out = append(out, ch)
+			continue
+		}
+		last := &out[len(out)-1]
+		if ch.StartLap > last.EndLap {
+			out = append(out, ch)
+			continue
+		}
+		if isFlag(last.Kind) && priority(ch.Kind) < priority(last.Kind) {
+			continue
+		}
+		if priority(ch.Kind) > priority(last.Kind) {
+			if last.StartLap < ch.StartLap {
+				last.EndLap = ch.StartLap - 1
+				out = append(out, ch)
+			} else {
+				*last = ch
+			}
+			continue
+		}
+		if ch.EndLap > last.EndLap {
+			ch.StartLap = last.EndLap + 1
+			if ch.StartLap <= ch.EndLap {
+				out = append(out, ch)
+			}
+		}
+	}
+	return out
+}
+
+func isFlag(kind string) bool {
+	return kind == KindSafetyCar || kind == KindVirtualSafetyCar || kind == KindRedFlag
+}
+
+func priority(kind string) int {
+	switch kind {
+	case KindStart, KindFinish:
+		return structuralPriority
+	case KindSafetyCar, KindVirtualSafetyCar, KindRedFlag:
+		return flagPriority
+	case KindPitPhase:
+		return pitPhasePriority
+	case KindDecisiveSwing:
+		return decisivePriority
+	default:
+		return 0
+	}
+}
+
+func messageLap(msg RaceControl, idx lapIndex) int {
+	if msg.LapNumber != nil && *msg.LapNumber > 0 {
+		return *msg.LapNumber
+	}
+	return idx.lapForTime(msg.Date)
+}
+
+func clampLap(lap, minLap, maxLap int) int {
+	if lap < minLap {
+		return minLap
+	}
+	if maxLap > 0 && lap > maxLap {
+		return maxLap
+	}
+	return lap
+}
+
+func parseTime(raw string) (time.Time, bool) {
+	if raw == "" {
+		return time.Time{}, false
+	}
+	at, err := time.Parse(time.RFC3339, raw)
+	if err != nil {
+		return time.Time{}, false
+	}
+	return at, true
+}
+
+func upperText(parts ...string) string {
+	return strings.ToUpper(strings.Join(parts, " "))
+}
+
+func firstNonEmpty(values ...string) string {
+	for _, value := range values {
+		if value != "" {
+			return value
+		}
+	}
+	return ""
+}
+
+func sortedDriverNumbers(drivers map[int]bool) []int {
+	out := make([]int, 0, len(drivers))
+	for driver := range drivers {
+		out = append(out, driver)
+	}
+	sort.Ints(out)
+	return out
+}
+
+func sliceToSet(values []int) map[int]bool {
+	out := make(map[int]bool, len(values))
+	for _, value := range values {
+		out[value] = true
+	}
+	return out
+}
+
+func minInt(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}

internal/chapters/chapters_test.go

@@ -0,0 +1,218 @@
+package chapters
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/AmanTahiliani/box-box/internal/models"
+)
+
+func TestDetectStructuralChapters(t *testing.T) {
+	chapters := Detect(nil, nil, testLaps(10, nil), 10)
+
+	if len(chapters) < 2 {
+		t.Fatalf("chapters len = %d, want at least start and finish", len(chapters))
+	}
+	if got := chapters[0]; got.Kind != KindStart || got.StartLap != 1 || got.EndLap != 1 {
+		t.Fatalf("start chapter = %+v, want L1-L1", got)
+	}
+	got := chapters[len(chapters)-1]
+	if got.Kind != KindFinish || got.StartLap != 9 || got.EndLap != 10 {
+		t.Fatalf("finish chapter = %+v, want L9-L10", got)
+	}
+}
+
+func TestDetectReturnsEmptyWithoutData(t *testing.T) {
+	if chapters := Detect(nil, nil, nil, 0); len(chapters) != 0 {
+		t.Fatalf("chapters = %+v, want empty", chapters)
+	}
+}
+
+func TestDetectFlagPeriods(t *testing.T) {
+	tests := []struct {
+		name      string
+		start     RaceControl
+		end       RaceControl
+		wantKind  string
+		wantTitle string
+	}{
+		{
+			name:      "safety car",
+			start:     rc(12, models.CategorySafetyCar, "", "SAFETY CAR DEPLOYED"),
+			end:       rc(15, models.CategorySafetyCar, "", "SAFETY CAR IN THIS LAP"),
+			wantKind:  KindSafetyCar,
+			wantTitle: "Safety Car (L12-L15)",
+		},
+		{
+			name:      "virtual safety car",
+			start:     rc(22, models.CategoryOther, "", "VSC DEPLOYED"),
+			end:       rc(24, models.CategoryOther, "", "VSC ENDING"),
+			wantKind:  KindVirtualSafetyCar,
+			wantTitle: "Virtual Safety Car (L22-L24)",
+		},
+		{
+			name:      "red flag",
+			start:     rc(31, models.CategoryFlag, models.FlagRed, "RED FLAG"),
+			end:       rc(33, models.CategoryFlag, models.FlagGreen, "GREEN FLAG"),
+			wantKind:  KindRedFlag,
+			wantTitle: "Red Flag (L31-L33)",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			chapters := Detect([]RaceControl{tt.start, tt.end}, nil, testLaps(40, nil), 40)
+			got := findKind(chapters, tt.wantKind)
+			if got == nil {
+				t.Fatalf("chapters = %+v, want %s", chapters, tt.wantKind)
+			}
+			if got.StartLap != rcLap(tt.start) || got.EndLap != rcLap(tt.end) || got.Title != tt.wantTitle {
+				t.Fatalf("flag chapter = %+v, want %s", *got, tt.wantTitle)
+			}
+		})
+	}
+}
+
+func TestDetectPitPhaseFromPitOutLapCluster(t *testing.T) {
+	pitOuts := map[int][]int{
+		5:  {1},
+		10: {2},
+		20: {3},
+		21: {4},
+		22: {5},
+		30: {6},
+		35: {7},
+		40: {8},
+		45: {9},
+		50: {10},
+	}
+	chapters := Detect(nil, nil, testLaps(55, pitOuts), 55)
+
+	got := findKind(chapters, KindPitPhase)
+	if got == nil {
+		t.Fatalf("chapters = %+v, want pit phase", chapters)
+	}
+	if got.StartLap != 20 || got.EndLap != 22 {
+		t.Fatalf("pit phase = %+v, want L20-L22", *got)
+	}
+	if len(got.DriverNumbers) != 3 || got.DriverNumbers[0] != 3 || got.DriverNumbers[2] != 5 {
+		t.Fatalf("pit phase drivers = %v, want [3 4 5]", got.DriverNumbers)
+	}
+}
+
+func TestDetectDecisiveSwingPersistsToFinish(t *testing.T) {
+	positions := []PositionSample{
+		pos(1, 1, 1),
+		pos(1, 16, 4),
+		pos(1, 55, 3),
+		pos(6, 16, 3),
+		pos(6, 55, 4),
+		pos(8, 44, 5),
+		pos(8, 63, 6),
+		pos(10, 44, 6),
+	}
+
+	chapters := Detect(nil, positions, testLaps(12, nil), 12)
+	got := findKind(chapters, KindDecisiveSwing)
+	if got == nil {
+		t.Fatalf("chapters = %+v, want decisive swing", chapters)
+	}
+	if got.StartLap != 6 || got.EndLap != 6 {
+		t.Fatalf("swing lap = %+v, want L6", *got)
+	}
+	if len(got.DriverNumbers) != 2 || got.DriverNumbers[0] != 16 || got.DriverNumbers[1] != 55 {
+		t.Fatalf("swing drivers = %v, want [16 55]", got.DriverNumbers)
+	}
+}
+
+func TestDetectFlagPeriodsWinOverConflictingChapters(t *testing.T) {
+	pitOuts := map[int][]int{
+		12: {1, 2},
+		13: {3, 4},
+		14: {5, 6},
+	}
+	rcs := []RaceControl{
+		rc(12, models.CategorySafetyCar, "", "SAFETY CAR DEPLOYED"),
+		rc(15, models.CategorySafetyCar, "", "SAFETY CAR IN THIS LAP"),
+	}
+
+	chapters := Detect(rcs, nil, testLaps(20, pitOuts), 20)
+	if got := findKind(chapters, KindSafetyCar); got == nil || got.StartLap != 12 || got.EndLap != 15 {
+		t.Fatalf("chapters = %+v, want safety car L12-L15", chapters)
+	}
+	if got := findKind(chapters, KindPitPhase); got != nil {
+		t.Fatalf("pit phase = %+v, want omitted under safety car", *got)
+	}
+	for i := 1; i < len(chapters); i++ {
+		if chapters[i].StartLap <= chapters[i-1].EndLap {
+			t.Fatalf("chapters overlap at %d: %+v then %+v", i, chapters[i-1], chapters[i])
+		}
+	}
+}
+
+func rcLap(r RaceControl) int {
+	if r.LapNumber == nil {
+		return 0
+	}
+	return *r.LapNumber
+}
+
+func findKind(chapters []Chapter, kind string) *Chapter {
+	for i := range chapters {
+		if chapters[i].Kind == kind {
+			return &chapters[i]
+		}
+	}
+	return nil
+}
+
+func testLaps(total int, pitOuts map[int][]int) []Lap {
+	var laps []Lap
+	for lap := 1; lap <= total; lap++ {
+		drivers := []int{1}
+		if pitDrivers := pitOuts[lap]; len(pitDrivers) > 0 {
+			drivers = pitDrivers
+		}
+		for _, driver := range drivers {
+			laps = append(laps, Lap{
+				DriverNumber: driver,
+				LapNumber:    lap,
+				DateStart:    lapTime(lap),
+				IsPitOutLap:  containsDriver(pitOuts[lap], driver),
+			})
+		}
+	}
+	return laps
+}
+
+func rc(lap int, category models.RaceControlCategory, flag models.Flag, message string) RaceControl {
+	return RaceControl{
+		Category:  category,
+		Flag:      flag,
+		Message:   message,
+		LapNumber: &lap,
+		Date:      lapTime(lap),
+	}
+}
+
+func pos(lap int, driver int, position int) PositionSample {
+	return PositionSample{
+		DriverNumber: driver,
+		Position:     position,
+		Date:         lapTime(lap),
+	}
+}
+
+func lapTime(lap int) string {
+	minute := lap - 1
+	return fmt.Sprintf("2025-05-25T13:%02d:00Z", minute)
+}
+
+func containsDriver(drivers []int, driver int) bool {
+	for _, candidate := range drivers {
+		if candidate == driver {
+			return true
+		}
+	}
+	return false
+}

internal/live/parser_test.go

@@ -273,6 +273,40 @@ func TestProcessTopicTrackStatus(t *testing.T) {
 	}
 }
 
+func TestProcessTopicSessionStatus(t *testing.T) {
+	state := live.NewState()
+	if !state.ProcessTopic("SessionStatus", json.RawMessage(`{"Status": "Finished"}`)) {
+		t.Fatal("SessionStatus should update state")
+	}
+	snap := state.Snapshot()
+	if snap.SessionStatus != "Finished" {
+		t.Fatalf("session status = %q, want Finished", snap.SessionStatus)
+	}
+	if !snap.SnapshotUpdated {
+		t.Fatal("SessionStatus should mark snapshot updated")
+	}
+}
+
+func TestSessionStatusIsActive(t *testing.T) {
+	tests := []struct {
+		status string
+		want   bool
+	}{
+		{"Started", true},
+		{"Resumed", true},
+		{"Finished", false},
+		{"Finalised", false},
+		{"Ends", false},
+		{"Aborted", false},
+		{"", false},
+	}
+	for _, tt := range tests {
+		if got := live.SessionStatusIsActive(tt.status); got != tt.want {
+			t.Errorf("SessionStatusIsActive(%q) = %v, want %v", tt.status, got, tt.want)
+		}
+	}
+}
+
 func TestProcessTopicRaceControlMessages(t *testing.T) {
 	state := live.NewState()
 	data := json.RawMessage(`{

internal/live/signalr.go

@@ -197,7 +197,7 @@ func connectToF1LegacySignalR(dataChan chan LiveStreamData) error {
 		return err
 	}
 
-	subscribeMsg := []byte(`{"H":"Streaming","M":"Subscribe","A":[["Heartbeat","TimingData","Position.z","CarData.z","DriverList","LapCount","ExtrapolatedClock","TrackStatus","RaceControlMessages","WeatherData","SessionInfo","TeamRadio","CurrentTyres","TimingAppData","TimingStats"]],"I":1}`)
+	subscribeMsg := []byte(`{"H":"Streaming","M":"Subscribe","A":[["Heartbeat","TimingData","Position.z","CarData.z","DriverList","LapCount","ExtrapolatedClock","TrackStatus","RaceControlMessages","WeatherData","SessionInfo","TeamRadio","CurrentTyres","TimingAppData","TimingStats","SessionStatus"]],"I":1}`)
 	err = c.WriteMessage(websocket.TextMessage, subscribeMsg)
 	if err != nil {
 		return err

internal/live/state.go

@@ -26,6 +26,7 @@ type State struct {
 	Weather            LiveWeatherData
 	Session            LiveSessionMeta
 	TeamRadio          []LiveRadioCapture
+	SessionStatus      string
 	TrackStatus        string
 	CurrentLap         int
 	TotalLaps          int
@@ -93,6 +94,7 @@ func (s *State) Snapshot() LiveStreamData {
 		Weather:            s.Weather,
 		Session:            s.Session,
 		TeamRadio:          cpyRadio,
+		SessionStatus:      s.SessionStatus,
 		TrackStatus:        s.TrackStatus,
 		CurrentLap:         s.CurrentLap,
 		TotalLaps:          s.TotalLaps,
@@ -273,6 +275,14 @@ func (s *State) ProcessTopic(topic string, data json.RawMessage) bool {
 			s.TrackStatus = ts.Status
 			updated = true
 		}
+	case "SessionStatus":
+		var ss struct {
+			Status string `json:"Status"`
+		}
+		if json.Unmarshal(data, &ss) == nil && ss.Status != "" {
+			s.SessionStatus = ss.Status
+			updated = true
+		}
 	case "RaceControlMessages":
 		var rcm struct {
 			Messages json.RawMessage `json:"Messages"`

internal/live/types.go

@@ -162,6 +162,7 @@ type LiveStreamData struct {
 	Weather            LiveWeatherData
 	Session            LiveSessionMeta
 	TeamRadio          []LiveRadioCapture
+	SessionStatus      string
 	TrackStatus        string // "1"=green "2"=yellow "4"=SC "5"=red "6"=VSC
 	CurrentLap         int
 	TotalLaps          int
@@ -173,3 +174,27 @@ type LiveStreamData struct {
 	PositionUpdated    bool                        `json:"-"`
 	SnapshotUpdated    bool                        `json:"-"`
 }
+
+// SessionStatusIsActive reports whether a raw F1 live timing SessionStatus
+// value represents an actively running session.
+func SessionStatusIsActive(status string) bool {
+	switch normalizeSessionStatus(status) {
+	case "started", "resumed":
+		return true
+	default:
+		return false
+	}
+}
+
+func normalizeSessionStatus(status string) string {
+	out := make([]rune, 0, len(status))
+	for _, r := range status {
+		switch {
+		case r >= 'A' && r <= 'Z':
+			out = append(out, r+'a'-'A')
+		case r >= 'a' && r <= 'z', r >= '0' && r <= '9':
+			out = append(out, r)
+		}
+	}
+	return string(out)
+}

internal/query/championship.go

@@ -26,6 +26,15 @@ type ChampionshipInputs struct {
 }
 
 // GetChampionshipInputs derives championship hub inputs from ingested season data.
+//
+// 2026 note: Bahrain (meeting 1282 / session 11261) and Saudi Arabia (1283 / 11269)
+// are cancelled due to Force Majeure (regional conflict) — OpenF1 returns no results
+// for those sessions. This is intentional, which is why 2026 shows Round 9/24 after
+// Silverstone instead of Round 11.
+//
+// Points: F1 Sprint points (SessionName == "Sprint") must be included alongside Race
+// points. Both appear as SessionType "Race" in OpenF1 /api/v1/sessions, so we match
+// on SessionName. Fix for #57.
 func (s *Service) GetChampionshipInputs(year int) (ChampionshipInputs, error) {
 	meetings, err := s.ListMeetingsByYear(year)
 	if err != nil {
@@ -51,60 +60,101 @@ func (s *Service) GetChampionshipInputs(year int) (ChampionshipInputs, error) {
 		}
 
 		raceKey := 0
+		sprintKey := 0
 		for _, sess := range sessions {
 			if strings.EqualFold(sess.SessionName, "Race") {
 				raceKey = sess.SessionKey
-				break
+			} else if strings.EqualFold(sess.SessionName, "Sprint") {
+				sprintKey = sess.SessionKey
 			}
 		}
-		if raceKey == 0 {
+		if raceKey == 0 && sprintKey == 0 {
 			continue
 		}
 
-		results, err := s.store.ListSessionResults(raceKey)
+		// Always build Races slice from the Race session only (for UI),
-		if err != nil {
+		// but include sprint points for standings.
-			return ChampionshipInputs{}, err
+		var raceResults []models.SessionResult
-		}
+		var raceGrid []models.StartingGrid
-		grid, err := s.store.ListStartingGrid(raceKey)
-		if err != nil {
-			return ChampionshipInputs{}, err
-		}
 
-		race := ChampionshipRace{
+		if raceKey != 0 {
-			Meeting:        meeting,
+			results, err := s.store.ListSessionResults(raceKey)
-			RaceSessionKey: raceKey,
+			if err != nil {
-			Results:        make([]models.SessionResult, 0, len(results)),
+				return ChampionshipInputs{}, err
-			Grid:           make([]models.StartingGrid, 0, len(grid)),
+			}
-		}
+			grid, err := s.store.ListStartingGrid(raceKey)
-		for _, result := range results {
+			if err != nil {
-			race.Results = append(race.Results, resultToModel(result))
+				return ChampionshipInputs{}, err
-		}
+			}
-		for _, entry := range grid {
+			race := ChampionshipRace{
-			race.Grid = append(race.Grid, gridToModel(entry))
+				Meeting:        meeting,
-		}
+				RaceSessionKey: raceKey,
-		inputs.Races = append(inputs.Races, race)
+				Results:        make([]models.SessionResult, 0, len(results)),
+				Grid:           make([]models.StartingGrid, 0, len(grid)),
+			}
+			for _, result := range results {
+				race.Results = append(race.Results, resultToModel(result))
+			}
+			for _, entry := range grid {
+				race.Grid = append(race.Grid, gridToModel(entry))
+			}
+			inputs.Races = append(inputs.Races, race)
+			raceResults = race.Results
 
-		if len(results) == 0 {
+			if len(results) > 0 {
-			continue
+				latestSessionKey = raceKey
-		}
+				latestMeetingKey = int(meeting.MeetingKey)
-
+				drivers, err := s.driversForSession(raceKey)
-		latestSessionKey = raceKey
+				if err != nil {
-		latestMeetingKey = int(meeting.MeetingKey)
+					return ChampionshipInputs{}, err
-		drivers, err := s.driversForSession(raceKey)
+				}
-		if err != nil {
+				for _, d := range drivers {
-			return ChampionshipInputs{}, err
+					inputs.DriverMap[d.DriverNumber] = d
-		}
+				}
-		for _, d := range drivers {
+				for _, result := range results {
-			inputs.DriverMap[d.DriverNumber] = d
+					pointsByDriver[result.DriverNumber] += result.Points
-		}
+					team := inputs.DriverMap[result.DriverNumber].TeamName
-
+					if team != "" {
-		for _, result := range results {
+						pointsByTeam[team] += result.Points
-			pointsByDriver[result.DriverNumber] += result.Points
+					}
-			team := inputs.DriverMap[result.DriverNumber].TeamName
+				}
-			if team != "" {
-				pointsByTeam[team] += result.Points
 			}
 		}
+
+		// Include sprint points if present.
+		// Note: 2026 has 4 sprints up to British GP (Chinese GP 11240, Miami 11275,
+		// Canadian 11286, British 11321) totaling e.g. ANT 21 = 4+3+6+8, RUS 26.
+		if sprintKey != 0 {
+			sprintResults, err := s.store.ListSessionResults(sprintKey)
+			if err != nil {
+				return ChampionshipInputs{}, err
+			}
+			if len(sprintResults) > 0 {
+				// Ensure driver map includes sprint-only drivers if any.
+				sprintDrivers, err := s.driversForSession(sprintKey)
+				if err == nil {
+					for _, d := range sprintDrivers {
+						if _, ok := inputs.DriverMap[d.DriverNumber]; !ok {
+							inputs.DriverMap[d.DriverNumber] = d
+						}
+					}
+				}
+				for _, result := range sprintResults {
+					pointsByDriver[result.DriverNumber] += result.Points
+					team := inputs.DriverMap[result.DriverNumber].TeamName
+					if team != "" {
+						pointsByTeam[team] += result.Points
+					}
+				}
+				// If this meeting had no race results (edge), still track latest.
+				if len(raceResults) == 0 {
+					latestSessionKey = sprintKey
+					latestMeetingKey = int(meeting.MeetingKey)
+				}
+			}
+		}
+		_ = raceResults
+		_ = raceGrid
 	}
 
 	inputs.Champ = derivedDriverStandings(pointsByDriver, latestMeetingKey, latestSessionKey)

internal/query/query_test.go

@@ -375,3 +375,56 @@ func TestGetWeekendWithSessions(t *testing.T) {
 		t.Fatalf("first session drivers = %+v, want available", weekend.Sessions[0].Datasets["drivers"])
 	}
 }
+
+func TestGetChampionshipInputsIncludesSprintPoints(t *testing.T) {
+	// Regression for #57: Race-only aggregation dropped Sprint points.
+	// Setup: same meeting 1229 has Race (9472) 25pts + Sprint (9473) 8pts => total 33.
+	svc := openTestService(t)
+	seedRaceHubData(t, svc.store)
+
+	// Add sprint session for same meeting
+	if err := svc.store.UpsertSession(store.Session{
+		SessionKey:  9473,
+		MeetingKey:  1229,
+		SessionName: "Sprint",
+		SessionType: "Race", // OpenF1 uses SessionType Race even for Sprint
+		DateStart:   "2025-05-24T13:00:00+00:00",
+	}); err != nil {
+		t.Fatalf("UpsertSession sprint error = %v", err)
+	}
+	if err := svc.store.UpsertSessionDriver(store.SessionDriver{
+		SessionKey: 9473, DriverNumber: 1, MeetingKey: 1229, TeamName: "Red Bull Racing",
+	}); err != nil {
+		t.Fatalf("UpsertSessionDriver sprint error = %v", err)
+	}
+
+	// Race points 25
+	if err := svc.store.UpsertSessionResult(store.SessionResult{
+		SessionKey: 9472, DriverNumber: 1, MeetingKey: 1229, Position: 1, Points: 25,
+	}); err != nil {
+		t.Fatalf("UpsertSessionResult race error = %v", err)
+	}
+	// Sprint points 8
+	if err := svc.store.UpsertSessionResult(store.SessionResult{
+		SessionKey: 9473, DriverNumber: 1, MeetingKey: 1229, Position: 1, Points: 8,
+	}); err != nil {
+		t.Fatalf("UpsertSessionResult sprint error = %v", err)
+	}
+
+	inputs, err := svc.GetChampionshipInputs(2025)
+	if err != nil {
+		t.Fatalf("GetChampionshipInputs() error = %v", err)
+	}
+	if len(inputs.Races) != 1 {
+		t.Fatalf("Races len = %d, want 1 race entry", len(inputs.Races))
+	}
+	if len(inputs.Champ) != 1 {
+		t.Fatalf("Champ len = %d, want 1", len(inputs.Champ))
+	}
+	if inputs.Champ[0].PointsCurrent != 33 {
+		t.Fatalf("PointsCurrent = %v, want 33 (25 race + 8 sprint)", inputs.Champ[0].PointsCurrent)
+	}
+	if len(inputs.Teams) != 1 || inputs.Teams[0].PointsCurrent != 33 {
+		t.Fatalf("Teams = %+v, want Red Bull 33", inputs.Teams)
+	}
+}

internal/query/racehub.go

@@ -4,6 +4,7 @@ import (
 	"database/sql"
 	"errors"
 
+	"github.com/AmanTahiliani/box-box/internal/chapters"
 	"github.com/AmanTahiliani/box-box/internal/models"
 	"github.com/AmanTahiliani/box-box/internal/store"
 )
@@ -52,6 +53,7 @@ type RaceHub struct {
 	RaceControl  []models.RaceControl   `json:"race_control"`
 	Weather      []models.Weather       `json:"weather"`
 	Laps         []models.Lap           `json:"laps"`
+	Chapters     []chapters.Chapter     `json:"chapters"`
 }
 
 // GetRaceHub loads ingested Race Hub datasets for a session from the local store.
@@ -80,6 +82,7 @@ func (s *Service) GetRaceHub(sessionKey int) (RaceHub, error) {
 		RaceControl:  []models.RaceControl{},
 		Weather:      []models.Weather{},
 		Laps:         []models.Lap{},
+		Chapters:     []chapters.Chapter{},
 	}
 
 	sess, err := s.store.GetSession(sessionKey)
@@ -248,6 +251,22 @@ func (s *Service) GetRaceHub(sessionKey int) (RaceHub, error) {
 		hub.Datasets["laps"] = availableLocal(len(hub.Laps))
 	}
 
+	hub.Chapters = chapters.Detect(hub.RaceControl, hub.Positions, hub.Laps, totalLaps(hub.Results, hub.Laps))
 	hub.Source = responseSource(hub.Datasets)
 	return hub, nil
 }
+
+func totalLaps(results []EnrichedResult, laps []models.Lap) int {
+	total := 0
+	for _, result := range results {
+		if result.NumberOfLaps > total {
+			total = result.NumberOfLaps
+		}
+	}
+	for _, lap := range laps {
+		if lap.LapNumber > total {
+			total = lap.LapNumber
+		}
+	}
+	return total
+}

internal/web/live.go

@@ -29,10 +29,21 @@ type SSEHub struct {
 	deregister chan *sseClient
 	broadcast  chan sseEvent
 
-	mu            sync.RWMutex
+	mu              sync.RWMutex
-	lastSnapshot  *live.LiveStreamData
+	activeSnapshot  *live.LiveStreamData
-	lastPositions map[string]live.LivePositionData
+	activePositions map[string]live.LivePositionData
-	isLive        bool
+	lastSnapshot    *live.LiveStreamData
+	lastPositions   map[string]live.LivePositionData
+	lastSnapshotAt  time.Time
+	isLive          bool
+}
+
+type liveStatePayload struct {
+	IsLive         bool                             `json:"is_live"`
+	Data           *live.LiveStreamData             `json:"data"`
+	LastSnapshot   *live.LiveStreamData             `json:"last_snapshot,omitempty"`
+	LastPositions  map[string]live.LivePositionData `json:"last_positions,omitempty"`
+	LastSnapshotAt *time.Time                       `json:"last_snapshot_at,omitempty"`
 }
 
 func newSSEHub() *SSEHub {
@@ -51,19 +62,16 @@ func (h *SSEHub) run() {
 		case c := <-h.register:
 			clients[c] = true
 			// Send catch-up snapshot so new clients see current state immediately.
-			h.mu.RLock()
+			state := h.State()
-			snap := h.lastSnapshot
+			if state.Data != nil || state.LastSnapshot != nil {
-			positions := cloneLivePositions(h.lastPositions)
+				if data, err := json.Marshal(state); err == nil {
-			live := h.isLive
-			h.mu.RUnlock()
-			if snap != nil {
-				if data, err := json.Marshal(map[string]any{"data": snap, "is_live": live}); err == nil {
 					select {
 					case c.ch <- formatSSEFrame("snapshot", data):
 					default:
 					}
 				}
 			}
+			positions := h.ActivePositions()
 			if len(positions) > 0 {
 				if data, err := json.Marshal(positions); err == nil {
 					select {
@@ -96,11 +104,125 @@ func formatSSEFrame(event string, data []byte) []byte {
 	return []byte(fmt.Sprintf("event: %s\ndata: %s\n\n", event, data))
 }
 
-// Snapshot returns the latest live data snapshot and whether a session is active.
+// State returns the active live snapshot and the retained in-memory archive.
-func (h *SSEHub) Snapshot() (*live.LiveStreamData, bool) {
+func (h *SSEHub) State() liveStatePayload {
 	h.mu.RLock()
 	defer h.mu.RUnlock()
-	return h.lastSnapshot, h.isLive
+	payload := liveStatePayload{
+		IsLive: h.isLive,
+	}
+	if h.isLive {
+		payload.Data = h.activeSnapshot
+	} else if h.lastSnapshot != nil {
+		payload.LastSnapshot = h.lastSnapshot
+		payload.LastPositions = cloneLivePositions(h.lastPositions)
+		if !h.lastSnapshotAt.IsZero() {
+			at := h.lastSnapshotAt
+			payload.LastSnapshotAt = &at
+		}
+	}
+	return payload
+}
+
+func (h *SSEHub) ActivePositions() map[string]live.LivePositionData {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	return cloneLivePositions(h.activePositions)
+}
+
+func (h *SSEHub) applySnapshot(data live.LiveStreamData, now time.Time) liveStatePayload {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	if live.SessionStatusIsActive(data.SessionStatus) {
+		h.isLive = true
+		h.activeSnapshot = &data
+		if data.PositionUpdated && len(data.Positions) > 0 {
+			h.activePositions = cloneLivePositions(data.Positions)
+		}
+		return liveStatePayload{IsLive: true, Data: h.activeSnapshot}
+	}
+
+	archivePositions := cloneLivePositions(h.activePositions)
+	if data.PositionUpdated && len(data.Positions) > 0 {
+		archivePositions = cloneLivePositions(data.Positions)
+	}
+	h.isLive = false
+	h.activeSnapshot = nil
+	h.activePositions = nil
+	if hasLiveSnapshotData(data) {
+		h.lastSnapshot = &data
+		h.lastSnapshotAt = now
+		h.lastPositions = archivePositions
+	}
+	return h.stateLocked()
+}
+
+func (h *SSEHub) applyPositions(data live.LiveStreamData) map[string]live.LivePositionData {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	if len(data.Positions) == 0 {
+		return nil
+	}
+	positions := cloneLivePositions(data.Positions)
+	if h.isLive {
+		h.activePositions = positions
+		return positions
+	}
+	if h.lastSnapshot != nil {
+		h.lastPositions = positions
+	}
+	return nil
+}
+
+func (h *SSEHub) deactivate(now time.Time) liveStatePayload {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	if h.activeSnapshot != nil {
+		h.lastSnapshot = h.activeSnapshot
+		h.lastPositions = cloneLivePositions(h.activePositions)
+		h.lastSnapshotAt = now
+	}
+	h.isLive = false
+	h.activeSnapshot = nil
+	h.activePositions = nil
+	return h.stateLocked()
+}
+
+func (h *SSEHub) stateLocked() liveStatePayload {
+	payload := liveStatePayload{IsLive: h.isLive}
+	if h.isLive {
+		payload.Data = h.activeSnapshot
+		return payload
+	}
+	if h.lastSnapshot != nil {
+		payload.LastSnapshot = h.lastSnapshot
+		payload.LastPositions = cloneLivePositions(h.lastPositions)
+		if !h.lastSnapshotAt.IsZero() {
+			at := h.lastSnapshotAt
+			payload.LastSnapshotAt = &at
+		}
+	}
+	return payload
+}
+
+func hasLiveSnapshotData(data live.LiveStreamData) bool {
+	return len(data.Drivers) > 0 ||
+		len(data.DriverInfo) > 0 ||
+		len(data.Tyres) > 0 ||
+		len(data.Telemetry) > 0 ||
+		len(data.RCMessages) > 0 ||
+		len(data.TeamRadio) > 0 ||
+		len(data.Stints) > 0 ||
+		data.Session.MeetingName != "" ||
+		data.Session.SessionName != "" ||
+		data.Session.SessionType != "" ||
+		data.TrackStatus != "" ||
+		data.CurrentLap != 0 ||
+		data.TotalLaps != 0 ||
+		data.Clock != ""
 }
 
 // runLiveFeeds launches background goroutines for the F1 SignalR feed and keepalive.
@@ -129,13 +251,8 @@ func (s *Server) signalRLoop() {
 			log.Printf("web: live feed ended: %v", err)
 		}
 
-		s.hub.mu.Lock()
+		state := s.hub.deactivate(time.Now())
-		s.hub.isLive = false
+		if payload, err := json.Marshal(state); err == nil {
-		s.hub.lastSnapshot = nil
-		s.hub.lastPositions = nil
-		s.hub.mu.Unlock()
-
-		if payload, err := json.Marshal(map[string]any{"data": nil, "is_live": false}); err == nil {
 			s.hub.broadcast <- sseEvent{name: "snapshot", data: payload}
 		}
 
@@ -167,24 +284,20 @@ func (s *Server) connectAndDrain() error {
 		select {
 		case data := <-dataChan:
 			now := time.Now()
-			s.hub.mu.Lock()
 			if data.SnapshotUpdated {
-				s.hub.lastSnapshot = &data
+				state := s.hub.applySnapshot(data, now)
-			}
+				if payload, err := json.Marshal(state); err == nil {
-			if data.PositionUpdated && len(data.Positions) > 0 {
-				s.hub.lastPositions = cloneLivePositions(data.Positions)
-			}
-			s.hub.isLive = true
-			s.hub.mu.Unlock()
-
-			if data.SnapshotUpdated {
-				if payload, err := json.Marshal(map[string]any{"data": data, "is_live": true}); err == nil {
 					s.hub.broadcast <- sseEvent{name: "snapshot", data: payload}
 				}
 			}
 
 			if data.PositionUpdated && len(data.Positions) > 0 && now.Sub(lastPositionBroadcast) >= 250*time.Millisecond {
-				if payload, err := json.Marshal(data.Positions); err == nil {
+				positions := s.hub.applyPositions(data)
+				if len(positions) > 0 {
+					payload, err := json.Marshal(positions)
+					if err != nil {
+						continue
+					}
 					s.hub.broadcast <- sseEvent{name: "positions", data: payload}
 					lastPositionBroadcast = now
 				}
@@ -217,11 +330,7 @@ func cloneLivePositions(in map[string]live.LivePositionData) map[string]live.Liv
 
 // handleLiveState returns the current live data snapshot as JSON.
 func (s *Server) handleLiveState(w http.ResponseWriter, r *http.Request) {
-	snap, isLive := s.hub.Snapshot()
+	writeJSON(w, s.hub.State())
-	writeJSON(w, map[string]any{
-		"is_live": isLive,
-		"data":    snap,
-	})
 }
 
 // handleSSEStream is the persistent SSE endpoint for live data.

internal/web/live_archive_test.go

@@ -0,0 +1,90 @@
+package web
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/AmanTahiliani/box-box/internal/live"
+)
+
+func TestSSEHubArchivesTerminalSessionSnapshot(t *testing.T) {
+	hub := newSSEHub()
+	now := time.Date(2026, 7, 4, 14, 0, 0, 0, time.UTC)
+	active := live.LiveStreamData{
+		SessionStatus: "Started",
+		Drivers: map[string]live.LiveDriverData{
+			"1": {RacingNumber: "1", Position: 1},
+		},
+		Positions: map[string]live.LivePositionData{
+			"1": {X: 100, Y: -50, Z: 2, Status: "OnTrack"},
+		},
+		PositionUpdated: true,
+		SnapshotUpdated: true,
+	}
+	if state := hub.applySnapshot(active, now); !state.IsLive || state.Data == nil {
+		t.Fatalf("active state = %+v, want live data", state)
+	}
+
+	terminal := active
+	terminal.SessionStatus = "Finished"
+	terminal.Positions = nil
+	terminal.PositionUpdated = false
+	state := hub.applySnapshot(terminal, now.Add(time.Minute))
+
+	if state.IsLive {
+		t.Fatal("terminal SessionStatus should not be live")
+	}
+	if state.Data != nil {
+		t.Fatalf("inactive state data = %+v, want nil", state.Data)
+	}
+	if state.LastSnapshot == nil || state.LastSnapshot.SessionStatus != "Finished" {
+		t.Fatalf("last snapshot = %+v, want terminal snapshot", state.LastSnapshot)
+	}
+	if got := state.LastPositions["1"]; got.X != 100 || got.Status != "OnTrack" {
+		t.Fatalf("last positions = %+v, want carried active positions", state.LastPositions)
+	}
+	if state.LastSnapshotAt == nil || !state.LastSnapshotAt.Equal(now.Add(time.Minute)) {
+		t.Fatalf("last snapshot time = %v, want %v", state.LastSnapshotAt, now.Add(time.Minute))
+	}
+}
+
+func TestHandleLiveStateKeepsArchiveOutOfActiveData(t *testing.T) {
+	hub := newSSEHub()
+	now := time.Date(2026, 7, 4, 14, 0, 0, 0, time.UTC)
+	hub.applySnapshot(live.LiveStreamData{
+		SessionStatus: "Finished",
+		Session:       live.LiveSessionMeta{MeetingName: "British Grand Prix", SessionName: "Race"},
+		Drivers: map[string]live.LiveDriverData{
+			"44": {RacingNumber: "44", Position: 1},
+		},
+		SnapshotUpdated: true,
+	}, now)
+
+	srv := &Server{hub: hub}
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/live/state", nil)
+	rec := httptest.NewRecorder()
+	srv.handleLiveState(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", rec.Code)
+	}
+	var resp liveStatePayload
+	if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("decode response: %v", err)
+	}
+	if resp.IsLive {
+		t.Fatal("archived snapshot should report is_live=false")
+	}
+	if resp.Data != nil {
+		t.Fatalf("archived snapshot leaked into data: %+v", resp.Data)
+	}
+	if resp.LastSnapshot == nil || resp.LastSnapshot.Session.MeetingName != "British Grand Prix" {
+		t.Fatalf("last snapshot = %+v, want archived race", resp.LastSnapshot)
+	}
+	if resp.LastSnapshotAt == nil {
+		t.Fatal("last_snapshot_at should be present for archived snapshots")
+	}
+}

internal/web/racehub.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 	"strconv"
 
+	"github.com/AmanTahiliani/box-box/internal/chapters"
 	"github.com/AmanTahiliani/box-box/internal/models"
 	"github.com/AmanTahiliani/box-box/internal/query"
 )
@@ -42,5 +43,6 @@ func emptyRaceHub(sessionKey int) query.RaceHub {
 		Drivers:      []models.Driver{},
 		Results:      []query.EnrichedResult{},
 		StartingGrid: []query.EnrichedGrid{},
+		Chapters:     []chapters.Chapter{},
 	}
 }

internal/web/racehub_test.go

@@ -119,6 +119,66 @@ func TestHandleRaceHubWithLocalData(t *testing.T) {
 	}
 }
 
+func TestHandleRaceHubIncludesChapters(t *testing.T) {
+	st := openTestStore(t)
+	seedRaceHubStore(t, st)
+	sessionKey := 9472
+	meetingKey := 1229
+
+	for lap := 1; lap <= 12; lap++ {
+		if err := st.UpsertLap(store.Lap{
+			SessionKey:   sessionKey,
+			DriverNumber: 1,
+			MeetingKey:   meetingKey,
+			LapNumber:    lap,
+			DateStart:    time.Date(2025, 5, 25, 13, lap-1, 0, 0, time.UTC).Format(time.RFC3339),
+			LapDuration:  75,
+		}); err != nil {
+			t.Fatalf("UpsertLap(%d) error = %v", lap, err)
+		}
+	}
+	for _, sample := range []store.PositionSample{
+		{SessionKey: sessionKey, DriverNumber: 1, MeetingKey: meetingKey, Date: "2025-05-25T13:00:00Z", Position: 1},
+		{SessionKey: sessionKey, DriverNumber: 16, MeetingKey: meetingKey, Date: "2025-05-25T13:00:00Z", Position: 4},
+		{SessionKey: sessionKey, DriverNumber: 55, MeetingKey: meetingKey, Date: "2025-05-25T13:00:00Z", Position: 3},
+		{SessionKey: sessionKey, DriverNumber: 16, MeetingKey: meetingKey, Date: "2025-05-25T13:05:00Z", Position: 3},
+		{SessionKey: sessionKey, DriverNumber: 55, MeetingKey: meetingKey, Date: "2025-05-25T13:05:00Z", Position: 4},
+	} {
+		if err := st.UpsertPositionSample(sample); err != nil {
+			t.Fatalf("UpsertPositionSample() error = %v", err)
+		}
+	}
+
+	srv := testServer(t, st)
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/race-hub?session_key=9472", nil)
+	rec := httptest.NewRecorder()
+	srv.handleRaceHub(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", rec.Code)
+	}
+
+	var hub query.RaceHub
+	if err := json.Unmarshal(rec.Body.Bytes(), &hub); err != nil {
+		t.Fatalf("decode response: %v", err)
+	}
+	if len(hub.Chapters) == 0 {
+		t.Fatalf("chapters = %+v, want generated chapters", hub.Chapters)
+	}
+	if hub.Chapters[0].Kind != "start" {
+		t.Fatalf("first chapter = %+v, want start", hub.Chapters[0])
+	}
+	foundSwing := false
+	for _, chapter := range hub.Chapters {
+		if chapter.Kind == "decisive_swing" {
+			foundSwing = true
+		}
+	}
+	if !foundSwing {
+		t.Fatalf("chapters = %+v, want decisive_swing", hub.Chapters)
+	}
+}
+
 func TestHandleMeetingsSourceLocal(t *testing.T) {
 	st := openTestStore(t)
 	seedRaceHubStore(t, st)

scripts/debug/f1_live_socket_probe.py

@@ -0,0 +1,264 @@
+#!/usr/bin/env python3
+"""Probe the official F1 live timing sockets for GPS position topics.
+
+This intentionally does not call OpenF1 REST. It connects directly to the F1
+SignalR endpoints used by the app and reports which topics arrive.
+"""
+
+from __future__ import annotations
+
+import argparse
+import base64
+import json
+import os
+import random
+import socket
+import ssl
+import struct
+import sys
+import time
+import urllib.parse
+import urllib.request
+
+
+RS = b"\x1e"
+CORE_NEGOTIATE = "https://livetiming.formula1.com/signalrcore/negotiate?negotiateVersion=1"
+CORE_WS_HOST = "livetiming.formula1.com"
+LEGACY_HUB = '[{"name":"Streaming"}]'
+TOPICS = [
+    "Heartbeat",
+    "TimingData",
+    "Position",
+    "Position.z",
+    "CarData",
+    "CarData.z",
+    "DriverList",
+    "LapCount",
+    "ExtrapolatedClock",
+    "TrackStatus",
+    "RaceControlMessages",
+    "WeatherData",
+    "SessionInfo",
+    "TeamRadio",
+    "CurrentTyres",
+    "TimingAppData",
+    "TimingStats",
+    "SessionStatus",
+    "TopThree",
+]
+
+
+class WebSocket:
+    def __init__(self, host: str, path: str, headers: dict[str, str] | None = None):
+        self.host = host
+        self.sock = ssl.create_default_context().wrap_socket(
+            socket.create_connection((host, 443), timeout=10),
+            server_hostname=host,
+        )
+        key = base64.b64encode(os.urandom(16)).decode("ascii")
+        request_headers = {
+            "Host": host,
+            "Upgrade": "websocket",
+            "Connection": "Upgrade",
+            "Sec-WebSocket-Key": key,
+            "Sec-WebSocket-Version": "13",
+            "Origin": "https://www.formula1.com",
+            "User-Agent": "Mozilla/5.0",
+        }
+        request_headers.update(headers or {})
+        lines = [f"GET {path} HTTP/1.1", *[f"{k}: {v}" for k, v in request_headers.items()], "", ""]
+        self.sock.sendall("\r\n".join(lines).encode("utf-8"))
+        response = self._read_http_response()
+        if b" 101 " not in response.split(b"\r\n", 1)[0]:
+            raise RuntimeError(response.decode("utf-8", "replace"))
+
+    def _read_http_response(self) -> bytes:
+        data = b""
+        while b"\r\n\r\n" not in data:
+            data += self.sock.recv(4096)
+        return data
+
+    def send_text(self, text: str) -> None:
+        payload = text.encode("utf-8")
+        header = bytearray([0x81])
+        if len(payload) < 126:
+            header.append(0x80 | len(payload))
+        elif len(payload) < 65536:
+            header.append(0x80 | 126)
+            header.extend(struct.pack("!H", len(payload)))
+        else:
+            header.append(0x80 | 127)
+            header.extend(struct.pack("!Q", len(payload)))
+        mask = random.randbytes(4) if hasattr(random, "randbytes") else os.urandom(4)
+        masked = bytes(b ^ mask[i % 4] for i, b in enumerate(payload))
+        self.sock.sendall(bytes(header) + mask + masked)
+
+    def recv_text(self, timeout: float = 5.0) -> str | None:
+        self.sock.settimeout(timeout)
+        while True:
+            first = self.sock.recv(2)
+            if not first:
+                return None
+            opcode = first[0] & 0x0F
+            masked = bool(first[1] & 0x80)
+            length = first[1] & 0x7F
+            if length == 126:
+                length = struct.unpack("!H", self._read_exact(2))[0]
+            elif length == 127:
+                length = struct.unpack("!Q", self._read_exact(8))[0]
+            mask = self._read_exact(4) if masked else b""
+            payload = self._read_exact(length)
+            if masked:
+                payload = bytes(b ^ mask[i % 4] for i, b in enumerate(payload))
+            if opcode == 0x8:
+                return None
+            if opcode == 0x9:
+                self._send_pong(payload)
+                continue
+            if opcode == 0x1:
+                return payload.decode("utf-8", "replace")
+
+    def _send_pong(self, payload: bytes) -> None:
+        self.sock.sendall(bytes([0x8A, len(payload)]) + payload)
+
+    def _read_exact(self, n: int) -> bytes:
+        chunks = []
+        remaining = n
+        while remaining:
+            chunk = self.sock.recv(remaining)
+            if not chunk:
+                raise EOFError("socket closed")
+            chunks.append(chunk)
+            remaining -= len(chunk)
+        return b"".join(chunks)
+
+    def close(self) -> None:
+        self.sock.close()
+
+
+def http_json(url: str, method: str = "GET", headers: dict[str, str] | None = None) -> tuple[dict, list[str]]:
+    req = urllib.request.Request(url, method=method, headers=headers or {})
+    with urllib.request.urlopen(req, timeout=15) as resp:
+        cookies = resp.headers.get_all("Set-Cookie") or []
+        return json.loads(resp.read()), cookies
+
+
+def core_probe(seconds: int) -> None:
+    print("== SignalR Core ==")
+    neg, cookies = http_json(
+        CORE_NEGOTIATE,
+        method="POST",
+        headers={"Origin": "https://www.formula1.com", "User-Agent": "Mozilla/5.0", "Content-Length": "0"},
+    )
+    token = urllib.parse.quote(neg["connectionToken"], safe="")
+    ws = WebSocket(
+        CORE_WS_HOST,
+        f"/signalrcore?id={token}",
+        {"Cookie": "; ".join(cookies)} if cookies else None,
+    )
+    try:
+        ws.send_text(json.dumps({"protocol": "json", "version": 1}, separators=(",", ":")) + RS.decode())
+        print("handshake:", repr(ws.recv_text()))
+        ws.send_text(
+            json.dumps(
+                {"type": 1, "target": "subscribe", "arguments": [TOPICS], "invocationId": "1"},
+                separators=(",", ":"),
+            )
+            + RS.decode()
+        )
+        collect(ws, seconds)
+    finally:
+        ws.close()
+
+
+def legacy_probe(seconds: int, bearer: str | None) -> None:
+    print("\n== Legacy SignalR ==")
+    query = urllib.parse.quote(LEGACY_HUB, safe="")
+    headers = {"User-Agent": "BestHTTP"}
+    if bearer:
+        headers["Authorization"] = f"Bearer {bearer}"
+    neg_url = f"https://livetiming.formula1.com/signalr/negotiate?clientProtocol=1.5&connectionData={query}"
+    try:
+        neg, cookies = http_json(neg_url, headers=headers)
+    except Exception as exc:
+        print("negotiate failed:", exc)
+        return
+    token = urllib.parse.quote(neg["ConnectionToken"], safe="")
+    path = f"/signalr/connect?clientProtocol=1.5&transport=webSockets&connectionToken={token}&connectionData={query}"
+    ws_headers = {"User-Agent": "BestHTTP"}
+    if cookies:
+        ws_headers["Cookie"] = "; ".join(cookies)
+    if bearer:
+        ws_headers["Authorization"] = f"Bearer {bearer}"
+    ws = WebSocket(CORE_WS_HOST, path, ws_headers)
+    try:
+        ws.send_text(json.dumps({"H": "Streaming", "M": "Subscribe", "A": [TOPICS], "I": 1}, separators=(",", ":")))
+        collect(ws, seconds)
+    finally:
+        ws.close()
+
+
+def collect(ws: WebSocket, seconds: int) -> None:
+    deadline = time.time() + seconds
+    seen: dict[str, int] = {}
+    while time.time() < deadline:
+        try:
+            message = ws.recv_text(timeout=min(5, max(1, deadline - time.time())))
+        except TimeoutError:
+            continue
+        if not message:
+            break
+        for frame in message.split(RS.decode()):
+            if not frame:
+                continue
+            try:
+                payload = json.loads(frame)
+            except json.JSONDecodeError:
+                continue
+            record_topics(payload, seen)
+    print("seen topics:")
+    for topic in sorted(seen):
+        print(f"  {topic}: {seen[topic]}")
+    if not any(topic.startswith("Position") for topic in seen):
+        print("  (no Position / Position.z topics observed)")
+
+
+def record_topics(payload: dict, seen: dict[str, int]) -> None:
+    result = payload.get("result") or payload.get("R")
+    if isinstance(result, dict):
+        for topic, data in result.items():
+            seen[topic] = seen.get(topic, 0) + 1
+            maybe_print_position(topic, data)
+    for message in payload.get("M") or []:
+        args = message.get("A") or []
+        if len(args) >= 2:
+            topic = args[0]
+            seen[topic] = seen.get(topic, 0) + 1
+            maybe_print_position(topic, args[1])
+    if payload.get("target") == "feed":
+        args = payload.get("arguments") or []
+        if len(args) >= 2:
+            topic = args[0]
+            seen[topic] = seen.get(topic, 0) + 1
+            maybe_print_position(topic, args[1])
+
+
+def maybe_print_position(topic: str, data) -> None:
+    if topic in {"Position", "Position.z"}:
+        text = json.dumps(data)[:600] if not isinstance(data, str) else data[:600]
+        print(f"POSITION TOPIC {topic}: {text}")
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--seconds", type=int, default=20)
+    parser.add_argument("--legacy", action="store_true", help="also probe legacy SignalR")
+    args = parser.parse_args()
+    core_probe(args.seconds)
+    if args.legacy:
+        legacy_probe(args.seconds, os.environ.get("BOXBOX_F1_LIVE_BEARER_TOKEN") or os.environ.get("F1_LIVE_BEARER_TOKEN"))
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

tests/command-center.spec.ts

@@ -28,6 +28,41 @@ test.describe('Command Center', () => {
     await expect(page.getByTestId(`rh-session-${FULL_SESSION}`)).toBeVisible()
   })
 
+  test('archived live snapshot does not mark command center live', async ({ page }) => {
+    await page.route('**/api/v1/live/state', (route) =>
+      route.fulfill({
+        contentType: 'application/json',
+        body: JSON.stringify({
+          is_live: false,
+          data: null,
+          last_snapshot: {
+            Drivers: { '1': { RacingNumber: '1', Position: 1 } },
+            DriverInfo: { '1': { RacingNumber: '1', Tla: 'VER', TeamColour: '3671C6' } },
+            Tyres: {},
+            RCMessages: [],
+            Weather: {},
+            Session: { MeetingName: 'Archived GP', SessionName: 'Race', SessionType: 'Race' },
+            TeamRadio: [],
+            SessionStatus: 'Finished',
+            TrackStatus: '1',
+            CurrentLap: 57,
+            TotalLaps: 57,
+            Clock: '',
+            ClockRefTime: '',
+            ClockExtrapolating: false,
+            Stints: {},
+          },
+          last_snapshot_at: '2026-07-04T14:00:00Z',
+        }),
+      }),
+    )
+
+    await page.goto('/')
+    await expect(page.getByTestId('command-center')).toBeVisible()
+    await expect(page.getByTestId('cc-live-status')).toContainText('No live session')
+    await expect(page.getByTestId('cc-live-status')).not.toContainText('Live session active')
+  })
+
   test('existing routes continue to work', async ({ page }) => {
     await page.goto(`/race-hub?session_key=${FULL_SESSION}`)
     await expect(page.getByTestId('race-hub')).toBeVisible()

tests/live-timing.spec.ts

@@ -239,4 +239,39 @@ test.describe('Live Timing (no session)', () => {
     await expect(page.getByTestId('live-empty')).toBeVisible()
     await expect(page.getByTestId('live-page')).toContainText('No live session active')
   })
+
+  test('renders an archived snapshot only after View Last Session', async ({ page }) => {
+    await page.route('**/api/v1/live/state', (route) =>
+      route.fulfill({
+        contentType: 'application/json',
+        body: JSON.stringify({
+          is_live: false,
+          data: null,
+          last_snapshot: {
+            ...raceSnapshot.data,
+            SessionStatus: 'Finished',
+          },
+          last_positions: {
+            '1': { x: 100, y: -50, z: 2, status: 'OnTrack' },
+          },
+          last_snapshot_at: '2026-07-04T14:00:00Z',
+        }),
+      }),
+    )
+    await page.route('**/api/v1/live/stream', (route) =>
+      route.fulfill({
+        contentType: 'text/event-stream',
+        body: 'event: heartbeat\ndata: {}\n\n',
+      }),
+    )
+
+    await page.goto('/live')
+    await expect(page.getByTestId('live-empty')).toContainText('No live session active')
+    await expect(page.getByText('Timing Tower')).toHaveCount(0)
+
+    await page.getByRole('button', { name: 'View Last Session' }).click()
+    await expect(page.getByTestId('live-archive-strip')).toContainText('Archived snapshot')
+    await expect(page.getByText('Timing Tower')).toBeVisible()
+    await expect(page.locator('.live-state')).toContainText('archive')
+  })
 })