feat: GripAnalysisView — car grip envelope visualization

- New GripAnalysisView with 4 scatter charts:
  1. Grip Envelope (peak G vs speed: lateral/accel/brake)
  2. Grip Circle (longitudinal vs lateral G scatter)
  3. Cornering Grip vs Speed
  4. Steering Response (steer angle vs lateral G)
- Summary stats: max lateral/accel/brake/combined G, peak lateral speed
- GripAnalysis types + type guard
- car_grip use case in SessionDetailView (quick stats + view button)
- Route /analysis/grip/:id
- Global .grid-4 CSS utility

src/assets/main.css

@@ -196,8 +196,12 @@ input, select, textarea {
   grid-template-columns: repeat(3, 1fr);
 }
 
+.grid-4 {
+  grid-template-columns: repeat(4, 1fr);
+}
+
 @media (max-width: 768px) {
-  .grid-2, .grid-3 {
+  .grid-2, .grid-3, .grid-4 {
     grid-template-columns: 1fr;
   }
 }

src/router/index.ts

@@ -30,6 +30,12 @@ const router = createRouter({
       component: () => import('@/views/ShiftPointsView.vue'),
       props: true,
     },
+    {
+      path: '/analysis/grip/:id',
+      name: 'grip-analysis',
+      component: () => import('@/views/GripAnalysisView.vue'),
+      props: true,
+    },
     {
       path: '/tracks',
       name: 'tracks',

src/types/index.ts

@@ -5,6 +5,7 @@
 
 export type UseCase =
   | 'shift_points'
+  | 'car_grip'
   | 'racing_line'
   | 'braking_analysis'
   | 'lap_times'
@@ -161,6 +162,43 @@ export interface ShiftPointAnalysis {
   total_frames_analyzed: number
 }
 
+// Car Grip Analysis (use_case = "car_grip")
+export interface GripEnvelopePoint {
+  speed_kmh: number
+  max_lateral_g: number
+  max_accel_g: number
+  max_brake_g: number
+  sample_count: number
+}
+
+export interface GripCirclePoint {
+  longitudinal_g: number
+  lateral_g: number
+}
+
+export interface SteeringResponsePoint {
+  steer: number
+  lateral_g: number
+  speed_kmh: number
+}
+
+export interface GripSummary {
+  max_lateral_g: number
+  max_accel_g: number
+  max_brake_g: number
+  max_combined_g: number
+  peak_lateral_speed_kmh: number
+}
+
+export interface CarGripAnalysis {
+  summary: GripSummary
+  grip_envelope: GripEnvelopePoint[]
+  grip_circle: GripCirclePoint[]
+  steering_response: SteeringResponsePoint[]
+  runs_analyzed: number
+  total_frames_analyzed: number
+}
+
 // Track Map Analysis (use_case = "track_mapping")
 export interface TrackPoint {
   x: number
@@ -237,7 +275,7 @@ export interface BuildTrackModelRequest {
 
 export type TrackMappingAnalysis = TrackMapAnalysis
 
-export type AnalysisResult = ShiftPointAnalysis | TrackMapAnalysis | NotImplementedResponse
+export type AnalysisResult = ShiftPointAnalysis | CarGripAnalysis | TrackMapAnalysis | NotImplementedResponse
 
 // ── Characteristics (aggregated across sessions) ──
 

src/utils/analysis.ts

@@ -1,4 +1,4 @@
-import type { ShiftPointAnalysis, TrackMapAnalysis } from '@/types'
+import type { ShiftPointAnalysis, CarGripAnalysis, TrackMapAnalysis } from '@/types'
 
 /**
  * Runtime type guard: checks if an unknown value is a ShiftPointAnalysis.
@@ -8,6 +8,14 @@ export function isShiftPointAnalysis(data: unknown): data is ShiftPointAnalysis
   return typeof data === 'object' && data !== null && 'gear_curves' in data
 }
 
+/**
+ * Runtime type guard: checks if an unknown value is a CarGripAnalysis.
+ * Uses the 'grip_envelope' discriminator field.
+ */
+export function isCarGripAnalysis(data: unknown): data is CarGripAnalysis {
+  return typeof data === 'object' && data !== null && 'grip_envelope' in data
+}
+
 /**
  * Runtime type guard: checks if an unknown value is a TrackMapAnalysis.
  * Uses the 'boundaries' discriminator field that the backend includes.

src/views/GripAnalysisView.vue

@@ -0,0 +1,300 @@
+<script setup lang="ts">
+import { ref, onMounted, computed } from 'vue'
+import { useRoute, useRouter } from 'vue-router'
+import { Scatter } from 'vue-chartjs'
+import {
+  Chart as ChartJS,
+  LinearScale,
+  PointElement,
+  Title,
+  Tooltip,
+  Legend,
+} from 'chart.js'
+import type { CarGripAnalysis } from '@/types'
+import { isCarGripAnalysis } from '@/utils/analysis'
+import * as api from '@/api/client'
+
+ChartJS.register(LinearScale, PointElement, Title, Tooltip, Legend)
+
+const route = useRoute()
+const router = useRouter()
+
+const sessionId = computed(() => route.params.id as string)
+const analysis = ref<CarGripAnalysis | null>(null)
+const loading = ref(true)
+const error = ref<string | null>(null)
+
+onMounted(async () => {
+  try {
+    const data = await api.getAnalysis(sessionId.value)
+    if (isCarGripAnalysis(data)) {
+      analysis.value = data
+    } else {
+      error.value = 'Analysis data not available or wrong type'
+    }
+  } catch (e: unknown) {
+    error.value = e instanceof Error ? e.message : 'Failed to load analysis'
+  } finally {
+    loading.value = false
+  }
+})
+
+const axisColor = '#8b8fa3'
+const gridColor = '#2a2e3f'
+
+const gripCurveData = computed(() => {
+  if (!analysis.value) return null
+  const env = analysis.value.grip_envelope
+  return {
+    datasets: [
+      {
+        label: 'Lateral G',
+        data: env.map((p) => ({ x: p.speed_kmh, y: p.max_lateral_g })),
+        borderColor: '#4f8ff7',
+        backgroundColor: '#4f8ff730',
+        showLine: true,
+        fill: false,
+        pointRadius: 2,
+        borderWidth: 2,
+        tension: 0.3,
+      },
+      {
+        label: 'Accel G',
+        data: env.map((p) => ({ x: p.speed_kmh, y: p.max_accel_g })),
+        borderColor: '#34d399',
+        backgroundColor: '#34d39930',
+        showLine: true,
+        fill: false,
+        pointRadius: 2,
+        borderWidth: 2,
+        tension: 0.3,
+      },
+      {
+        label: 'Brake G',
+        data: env.map((p) => ({ x: p.speed_kmh, y: -p.max_brake_g })),
+        borderColor: '#f87171',
+        backgroundColor: '#f8717130',
+        showLine: true,
+        fill: false,
+        pointRadius: 2,
+        borderWidth: 2,
+        tension: 0.3,
+      },
+    ],
+  }
+})
+
+const gripCurveOptions = {
+  responsive: true,
+  plugins: {
+    legend: { labels: { color: axisColor } },
+    title: { display: true, text: 'Grip Envelope — Peak G vs Speed', color: '#e2e4ea' },
+  },
+  scales: {
+    x: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'Speed (km/h)', color: axisColor } },
+    y: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'G-force', color: axisColor } },
+  },
+}
+
+const gripCircleData = computed(() => {
+  if (!analysis.value) return null
+  return {
+    datasets: [
+      {
+        label: 'G-force samples',
+        data: analysis.value.grip_circle.map((p) => ({ x: p.longitudinal_g, y: p.lateral_g })),
+        backgroundColor: '#4f8ff720',
+        borderColor: '#4f8ff7',
+        pointRadius: 1.5,
+        showLine: false,
+      },
+    ],
+  }
+})
+
+const gripCircleOptions = {
+  responsive: true,
+  plugins: {
+    legend: { display: false },
+    title: { display: true, text: 'Grip Circle — Longitudinal vs Lateral G', color: '#e2e4ea' },
+  },
+  scales: {
+    x: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'Longitudinal G (brake ← → accel)', color: axisColor } },
+    y: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'Lateral G (right ← → left)', color: axisColor } },
+  },
+}
+
+const steerResponseData = computed(() => {
+  if (!analysis.value) return null
+  return {
+    datasets: [
+      {
+        label: 'Samples',
+        data: analysis.value.steering_response.map((p) => ({ x: p.steer, y: p.lateral_g })),
+        backgroundColor: '#fbbf2420',
+        borderColor: '#fbbf24',
+        pointRadius: 1.5,
+        showLine: false,
+      },
+    ],
+  }
+})
+
+const steerResponseOptions = {
+  responsive: true,
+  plugins: {
+    legend: { display: false },
+    title: { display: true, text: 'Steering Response — Steer Angle vs Lateral G', color: '#e2e4ea' },
+  },
+  scales: {
+    x: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'Steering Input (right ← → left)', color: axisColor } },
+    y: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'Lateral G', color: axisColor } },
+  },
+}
+
+const speedVsSteerData = computed(() => {
+  if (!analysis.value) return null
+  const env = analysis.value.grip_envelope
+  return {
+    datasets: [
+      {
+        label: 'Peak lateral G per speed bin',
+        data: env.map((p) => ({ x: p.speed_kmh, y: p.max_lateral_g })),
+        borderColor: '#a78bfa',
+        backgroundColor: '#a78bfa30',
+        showLine: true,
+        fill: false,
+        pointRadius: 2,
+        borderWidth: 2,
+        tension: 0.3,
+      },
+    ],
+  }
+})
+
+const speedVsSteerOptions = {
+  responsive: true,
+  plugins: {
+    legend: { labels: { color: axisColor } },
+    title: { display: true, text: 'Cornering Grip vs Speed', color: '#e2e4ea' },
+  },
+  scales: {
+    x: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'Speed (km/h)', color: axisColor } },
+    y: { ticks: { color: axisColor }, grid: { color: gridColor }, title: { display: true, text: 'Peak Lateral G', color: axisColor } },
+  },
+}
+</script>
+
+<template>
+  <div class="grip-analysis">
+    <div class="flex items-center gap-2 mb-3">
+      <button class="btn btn-secondary btn-sm" @click="router.back()">← Back</button>
+      <h2 class="page-title">Car Grip Analysis</h2>
+    </div>
+
+    <div v-if="loading" class="card text-secondary">Loading analysis...</div>
+    <div v-if="error" class="card text-error">{{ error }}</div>
+
+    <template v-if="analysis">
+      <!-- Summary Stats -->
+      <div class="stat-grid mb-3">
+        <div class="stat-card">
+          <span class="stat-label">Max Lateral G</span>
+          <span class="stat-value mono">{{ analysis.summary.max_lateral_g.toFixed(2) }}</span>
+          <span class="stat-sub">at {{ Math.round(analysis.summary.peak_lateral_speed_kmh) }} km/h</span>
+        </div>
+        <div class="stat-card">
+          <span class="stat-label">Max Accel G</span>
+          <span class="stat-value mono">{{ analysis.summary.max_accel_g.toFixed(2) }}</span>
+        </div>
+        <div class="stat-card">
+          <span class="stat-label">Max Brake G</span>
+          <span class="stat-value mono">{{ analysis.summary.max_brake_g.toFixed(2) }}</span>
+        </div>
+        <div class="stat-card">
+          <span class="stat-label">Max Combined G</span>
+          <span class="stat-value mono">{{ analysis.summary.max_combined_g.toFixed(2) }}</span>
+        </div>
+        <div class="stat-card">
+          <span class="stat-label">Frames Analyzed</span>
+          <span class="stat-value mono">{{ analysis.total_frames_analyzed.toLocaleString() }}</span>
+        </div>
+      </div>
+
+      <!-- Charts -->
+      <div class="chart-grid">
+        <div class="chart-card">
+          <Scatter v-if="gripCurveData" :data="gripCurveData" :options="gripCurveOptions" />
+        </div>
+        <div class="chart-card">
+          <Scatter v-if="gripCircleData" :data="gripCircleData" :options="gripCircleOptions" />
+        </div>
+        <div class="chart-card">
+          <Scatter v-if="speedVsSteerData" :data="speedVsSteerData" :options="speedVsSteerOptions" />
+        </div>
+        <div class="chart-card">
+          <Scatter v-if="steerResponseData" :data="steerResponseData" :options="steerResponseOptions" />
+        </div>
+      </div>
+    </template>
+  </div>
+</template>
+
+<style scoped>
+.page-title {
+  font-size: 1.5rem;
+  margin: 0;
+}
+
+.stat-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
+  gap: 0.75rem;
+}
+
+.stat-card {
+  display: flex;
+  flex-direction: column;
+  gap: 0.15rem;
+  padding: 0.75rem;
+  background: var(--color-background);
+  border-radius: var(--radius-sm);
+}
+
+.stat-label {
+  font-size: 0.7rem;
+  color: var(--color-text-muted);
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+}
+
+.stat-value {
+  font-size: 1.5rem;
+  font-weight: 700;
+  color: var(--color-primary);
+}
+
+.stat-sub {
+  font-size: 0.75rem;
+  color: var(--color-text-muted);
+}
+
+.chart-grid {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 1rem;
+}
+
+@media (max-width: 900px) {
+  .chart-grid {
+    grid-template-columns: 1fr;
+  }
+}
+
+.chart-card {
+  padding: 1rem;
+  background: var(--color-surface);
+  border-radius: var(--radius);
+  border: 1px solid var(--color-border);
+}
+</style>

src/views/SessionDetailView.vue

@@ -2,8 +2,8 @@
 import { ref, onMounted, computed } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useSessionsStore } from '@/stores/sessions'
-import type { ShiftPointAnalysis, TrackMapAnalysis } from '@/types'
+import type { ShiftPointAnalysis, CarGripAnalysis, TrackMapAnalysis } from '@/types'
-import { isShiftPointAnalysis, isTrackMapAnalysis } from '@/utils/analysis'
+import { isShiftPointAnalysis, isCarGripAnalysis, isTrackMapAnalysis } from '@/utils/analysis'
 import * as api from '@/api/client'
 
 const props = defineProps<{
@@ -56,6 +56,14 @@ const trackAnalysis = computed((): TrackMapAnalysis | null => {
   return null
 })
 
+const gripAnalysis = computed((): CarGripAnalysis | null => {
+  if (!analysisData.value) return null
+  if (isCarGripAnalysis(analysisData.value)) {
+    return analysisData.value
+  }
+  return null
+})
+
 onMounted(async () => {
   await store.fetchSession(sessionId.value)
 })
@@ -101,6 +109,8 @@ function viewAnalysis() {
   if (!session.value) return
   if (session.value.use_case === 'shift_points') {
     router.push({ name: 'shift-points', params: { id: session.value.id } })
+  } else if (session.value.use_case === 'car_grip') {
+    router.push({ name: 'grip-analysis', params: { id: session.value.id } })
   }
 }
 
@@ -339,8 +349,28 @@ async function handleBuildTrack() {
             </div>
           </div>
 
+          <!-- Quick stats for car grip -->
+          <div v-if="gripAnalysis" class="analysis-stats grid grid-4 mb-2">
+            <div class="stat-card">
+              <span class="stat-label">Max Lateral G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_lateral_g.toFixed(2) }}</span>
+            </div>
+            <div class="stat-card">
+              <span class="stat-label">Max Accel G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_accel_g.toFixed(2) }}</span>
+            </div>
+            <div class="stat-card">
+              <span class="stat-label">Max Brake G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_brake_g.toFixed(2) }}</span>
+            </div>
+            <div class="stat-card">
+              <span class="stat-label">Max Combined G</span>
+              <span class="stat-value mono">{{ gripAnalysis.summary.max_combined_g.toFixed(2) }}</span>
+            </div>
+          </div>
+
           <div class="flex gap-2">
-            <button v-if="session.use_case === 'shift_points'" class="btn btn-primary" @click="viewAnalysis">
+            <button v-if="session.use_case === 'shift_points' || session.use_case === 'car_grip'" class="btn btn-primary" @click="viewAnalysis">
               📊 View Full Analysis
             </button>
             <button class="btn btn-secondary" @click="handleReAnalyze">