Architecture

Welch Race Companion is a Welch Software product: live GT7 LAN HUD with a pace-vs-best track map, rule-based voice engineer (optional Pace coaching vs your session best), Tracks elevation relief, and Sport Mode companion for Android and iPhone.

Modules

• core — Kotlin Multiplatform (JVM / Android / iOS): UDP, Salsa20, packet C parser, session, TrackMapBuilder, engineer / PaceCoach, tuning, Find PS5, simulator
• core.catalog / core.sport — bundled cars (~584), tracks (~122), makers; Sport week models + PSN sanitize
• app — Compose Multiplatform HUD (connect, race, audio-only, setup) + Tracks Layout / Relief card + Android TTS / iOS AVSpeechSynthesizer
• app.gt7 — optional companion client is this Worker’s API (profile / sport week); fail soft
• iosApp — Xcode host that embeds the GtDash framework
• web — PC harness (Ktor + synthetic sim)
• site — this Cloudflare Workers marketing site + companion API

Maps & voice

• HUD map — flat outline; denser Yours/Ours rings; green/red pace ribbon vs this stint’s best; Near crop; live vs-best gap
• Tracks Relief — extruded elevation with low→high tint on catalog detail (not on the race HUD)
• Voice — InsightEngine + opt-in PaceCoach → CommsGate → system TTS. Pace tips compare only to your session-best flying lap

Ports

• Heartbeat to PS5: UDP 33739 (payload C, packet C / 368 bytes, includes A, B, and ~)
• Telemetry from PS5: UDP 33740
• Find PS5: last saved IP, then this Wi-Fi /24 unicast scan
• Companion API: GET /api/health, POST /api/events (anonymous product diagnostics, opt-out), /api/racer/:psn, /api/sport/week

Companion vs hot path

UDP telemetry stays on the LAN and never depends on HTTP. Profile Online ID is device-local (no password). Catalogs are bundled offline. Circuit outlines come from a bundled pack with denser flying-lap and on-device learn/save fallback. Companion profile / sport / garage class data uses the GridStats JSON API via a Worker Bearer token. Track and car pictures load from GridStats hosted CDN assets. Player pages are outbound links only.

Hard rules

• Never claim tire wear (not in the GT7 stream).
• Tuning sheets are community approximations with a disclaimer.
• SetupHints are suggestions — never auto-applied.
• Not affiliated with Polyphony Digital or Sony.

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