LIVE TRACK MODE Pixel 10 Gemma 4 E2B Sonoma Raceway 289 Tests

Pitwall:
Real-Time AI
Race Coach
— On Device.

Move beyond the reactive post-session debrief of Garmin Catalyst or AiM Solo. Pitwall runs entirely on Pixel 10 via Termux — no cell coverage required. Sub-50ms hot-path coaching grounded in Ross Bentley's pedagogy, adapting to your skill level in real time.

Explore Architecture View 17 ADRs

<50ms Hot Path

289 Tests Pass

50 API Routes

12 Corners

Sonoma T3 · Carousel

▶ TRAIL BRAKE THROUGH FIRST APEX

LIVE

Speed

68km/h

Brake

4.2bar

Lat G

0.81g

Live Telemetry · Lap Delta

1:42.82 ▲ +0.12

SECTOR 2: ▼ −0.04 CORNER: T3A

auto_stories

Domain Expertise Layer

9 pedagogical vectors drawn from Ross Bentley's Performance Driving Illustrated. T-Rod Sonoma transcript encoded as canonical phrases. Per-corner doctrine for all 12 turns at Sonoma Raceway.

Bentley Logic 9 Vectors T-Rod Anchors

memory

Split-Brain Engine

Hot path (sonic model + RuleCoach) fires in <50ms — zero LLM calls during driving. Warm path (Gemma 4 E2B via LiteRT-LM) provides tactical depth in 2–4s. CoachArbiter holds 78% of cues. Silence is coaching.

<50ms Hot Gemma 4 E2B 78% Suppressed

shield_lock

Private & Offline

Zero cloud dependency for the core coaching loop. All telemetry persists in local DuckDB on-device. Bridge binds to 127.0.0.1 only. Optional cloud Gemini debrief sends aggregate stats only — never raw frames.

DuckDB Local Air-Gapped 127.0.0.1

Validated Cue Distribution

Sourced from 11,737 real Sonoma telemetry frames · BMW M3 E46

21.7% Silence = Doing It Right

Grip Tone — continuous pitch, always on 55.2%

Brake Approach — ascending pitch at corner entry 42.3%

Speed Delta (LSTM) — actual vs. predicted >5 km/h ~18%

Silence — straights, clean driving 21.7%

Throttle Cue 3.2%

Coast Warning 3.0%

Trail Brake 1.2%

Corner Chime 0.5%

Cues Held 78%

Total Frames 11,737

Architecture Breakdown

Hot Path · <50ms

Sonic model + RuleCoach deterministic engine. Zero LLM calls during driving. Grip tones, shift indicators, brake approach alerts. Pure TPU compute.

Files: sonic_model.py · coach_engine.py:RuleCoach

Warm Path · 2–4s

Gemma 4 E2B on-device via LiteRT-LM (MediaPipe Genai). Paddock brief & debrief. System prompt contains Bentley pedagogy + Sonoma corner doctrine.

Files: coach_engine.py:LitertCoach · gemma-4-E2B-it.litertlm

Cold Path · 8–15s (Optional)

Cloud Gemini post-session debrief. Requires GEMINI_API_KEY. Sends aggregate stats only — zero raw telemetry frames. Graceful no-op without key.

Files: pitwall_bridge.py:POST /coach/debrief

Data Flow · End-to-End

Trust Gates · CoachArbiter Logic

Priority Levels

P3 Safety · P2 Technique

P1 Strategy · P0 Flavor

State Machine

OPEN → DELIVERING

→ COOLDOWN → BLACKOUT

Motion gate ACTIVE

Skill classification BEGINNER / INTER / ADV

Phase filter (entry/apex/exit) CORNER-AWARE

Cue suppression rate 78% HELD

Arbiter prevents LLM suggestions from overriding safety-critical deterministic grip tones. P0 safety always preempts any LLM output.

Latency Budget · Wall-Clock

Component	Budget	Source
CAN frame → DuckDB row	< 5ms	can_reader.py
Hot path: sonic cue	< 50ms	ADR-002
RuleCoach (in-process)	< 100ms	coach_engine.py
LiteRT-LM Gemma 4 E2B	2–4s	ADR-012
Capability recompute	< 200ms	ADR-015
Cloud Gemini debrief	8–15s	Optional
Smoke: 8,273 frames + 50 endpoints	~12s	smoke_test.py

Google Stack · On-Device First

Layer	Component	Model / ID	Where
Hot	Sonic Model	Rule engine (no LLM)	sonic_model.py
Warm	LiteRT-LM + MediaPipe Genai	gemma-4-E2B-it.litertlm	LitertCoach
Warm	Pixel 10 TPU / AiCore	com.google.ai.edge	validate_litert.py
Cold	Gemini Debrief	gemini-2.5-flash (optional)	pitwall_bridge.py
Store	DuckDB + Parquet	Local-only, no sync	pitwall_bridge.py

Bentley Curriculum · Pedagogical Vectors

Vector	Condition	Beginner	Advanced
Weight Xfer	gLong/gLat spike	"Smooth it out"	"Load rate exceeded"
Trail Brake	Brake >10% + gLat >0.4g	"Carry brake in"	"Trail to apex"
Coasting	No throttle >30 km/h	"Leaving time out"	"6.3% lap in coast"
Braking	Overshoot	"Brake earlier"	"Compress zone 1"
Line	Early apex	"Wait to turn"	"Deepen entry"
Throttle	Post-apex hesitation	"Squeeze sooner"	"Verify traction"

Sonoma Corner Doctrine

12 corners · 4,258m · 49m elevation range · OSM-derived GPS centerline

Field Test: May 23, 2026 BMW M3 E46

T2 GEAR 3

Late apex hairpin. Commitment to trail brake past the apex curb separates laps.

Apex Speed52 km/h

T-Rod Anchor"Brake late"

T3 GEAR 3

The Carousel

Double-apex. Trail brake past first apex. Commitment is everything. Common mistake: rushing throttle on exit → understeer.

Apex Speed68 km/h

Landmark"The Bridge"

T3A GEAR 3

Second apex of the Carousel. Patience on throttle — exit feeds the long back straight.

Apex Speed72 km/h

T-Rod Anchor"Patience on throttle"

T6 GEAR 4

High-speed sweeper. Balance throttle through full arc. Trust the grip — coasting here loses 0.4s/lap.

Apex Speed105 km/h

DangerK-WALL BEND

T7 GEAR 3

Medium-speed, decreasing radius. Trail brake to hold mid-corner speed. Early throttle creates understeer.

Apex Speed78 km/h

Bentley VectorTrail Brake

T9–10 GEAR 3

Calamity Corner

Elevation change complicates braking. Use the curb on entry. T-Rod: "Distance is king" — don't compromise exit speed.

Apex Speed55 km/h

T-Rod Anchor"Distance is king"

T11 GEAR 3

Off-camber. Use the curb — it's there for a reason. T-Rod: "Trust the curb." Entry commitment sets up T12 exit.

Apex Speed62 km/h

T-Rod Anchor"Trust the curb"

T12 GEAR 4

Final Corner

Last corner onto the main straight. Wide entry, late apex. Maximize throttle at apex — exit speed compounds onto the straight.

Apex Speed85 km/h

PrioritySpeed Exit

Analytics Surface

50 REST endpoints · 11 post-session analysers · DuckDB local

timer Lap Times

donut_large Sector Splits

grade Corner Grades

show_chart Pedal Curves

scatter_plot G-G Diagram

speed Speed Delta

bolt Ideal Lap

route Throttle Heatmap

settings_input_component CAN Signals

trending_up Driver Evolution

gps_fixed Track Map

bar_chart Lap Distribution

Technical Stack · As Shipped

Layer	Technology	Details
Edge Compute	Pixel 10 + Termux	runit supervisor · Termux:Boot · Doze-safe via wake lock
On-Device LLM	Gemma 4 E2B · LiteRT-LM	MediaPipe Genai · gemma-4-E2B-it.litertlm · warm path only
CAN Ingest	python-can + cantools	USB-CAN adapter (CANable Pro / Macchina M2) · 29 signals · 9 messages · pitwall.dbc
Persistence	DuckDB + Parquet	Local-only · wide table (11 signals) + tall sink (any signal) · user-driven export
Bridge API	Flask · 50 routes	pitwall_bridge.py · 127.0.0.1:8765 · adb reverse tunnel for dev
Frontend	Vue 3 + Vite + Tailwind	GBA retro aesthetic · PWA manifest · pixel-art frames · in-progress (ADR-016)
Track Data	Sonoma JSON · OSM GPS	139 KB · 12 corners · real GPS centerline · gold-standard lap · marker thumbnails
ML Models	LSTM v1 + v3	Speed delta prediction · validated on 8,273 Sonoma frames
Testing	pytest · smoke suite	289 passing · 0 skipped · 51 smoke assertions · virtual CAN bus (no kernel modules)

Architecture Decision Records

17 ADRs · docs/adr/index.md

ADR-002 Core

Split-Brain + Message Arbiter

Hot/warm/cold separation with priority queue. CoachArbiter holds 78% of cues.

ADR-003 LLM

Gemma 4 as Edge LLM

Gemma 4 E2B via LiteRT-LM for warm path. No cloud required for coaching loop.

ADR-005 Pedagogy

Pedagogical Vector Retrieval

9 Bentley vectors encoded as retrieval keys. Every cue traces back to curriculum.

ADR-009 Resilience

Graceful Degradation Protocol

Bridge dies → sonic_model fallback. LLM timeout → cached phrases. Network drops → Antigravity pipeline.

ADR-015 Data

Universal Telemetry Sink

Wide table (11 canonical signals) + tall sink (any signal). 54-entry OBD2 signal registry. Any car, any feed.

ADR-017 Current

Three-Tier Coach Architecture

Hot (no LLM) / Warm (Gemma 4 E2B) / Cold (optional Gemini). Audio-first with HUD fallback.

ADR-016 Frontend

USB-CAN Ingest + Vue PWA

Pivot from BLE+Flutter to USB-CAN+Vue 3. GBA retro aesthetic. Same Flask backend bridges both.

ADR-006 Sensors

Sensor Fusion · Racelogic + OBD

ASOF + lerp interpolation. Axis switching (GPS / lap-distance / signal-name). Uniform-grid resampling.

More ADRs

docs/adr/index.md

Mission Lifecycle · Day at Sonoma

Arrive

5 MIN

Hardware pair. GET /health. USB-CAN connect.

Pre-Brief

2–4 MIN

Set 1–3 goals. Gemma 4 reads weather, picks focus corners.

Out-Lap

1 LAP

P3 safety cues only. Sonic model at 50% volume. Sensor calibrate.

Hot Laps

4–8 LAPS

Full co-pilot. Audio + HUD. Cue volume scales with lap-time delta to goal.

Cool-Down

1 LAP

Chimes only. No coaching. Driver builds mental model.

Debrief

5–15 MIN

POST /coach/debrief. Lap table, friction circle, corner A–F grades.

Engineering & Pedagogy Team

Team 2 · Intermediate · BMW M3 E46

Hemanth HM

Tech Lead · Platform Arch

Simon Margolis

Edge · Telemetry

Taha Bouhsine

AGY Pipeline

Vijay Vivekanand

Data Reasoning

Aileen Villanueva

UX · Frontend

Acknowledgements: Ross Bentley · Performance Driving Illustrated · T-Rod Sonoma Transcript · Racelogic VBO Format · python-can · cantools · DuckDB · MediaPipe Genai · LiteRT-LM

terminal GitHub Repo description 17 ADRs api API Docs
50 endpoints account_tree Architecture school Pedagogy
Bentley curriculum

Pitwall:Real-Time AIRace Coach— On Device.