---
id: SEED-001
status: dormant
planted: 2026-03-25
planted_during: v2.0 Phase 11 (Core IPD Pipe Command)
trigger_when: Phase 11 research or Phase 13 (Slider Persistence) planning
scope: Small
---

# SEED-001: Investigate Tundra SiP for IPD persistence without lighthouse_console

## Why This Matters

The Beyond 2 integrates the Tundra TL448K6D SiP (System-in-Package) for all SteamVR tracked device needs. The SiP or its driver may have built-in features to handle IPD config writes when certain properties are set on the HMD container, which could eliminate the need for lighthouse_console.exe entirely.

Currently, the only known way to persist IPD changes to headset config is via `lighthouse_console.exe downloadconfig/uploadconfig`, which causes ~20 seconds of tracking disruption due to USB connection takeover. If the Tundra SiP driver handles this natively (e.g., responding to Prop_UserIpdMeters_Float changes by writing to its own config), it would be a dramatically simpler and non-disruptive persistence path.

## When to Surface

**Trigger:** Phase 11 research (config reading strategy) or Phase 13 planning (IPD persistence)

This seed should be presented during `/gsd:new-milestone` when the milestone scope matches any of these conditions:
- IPD persistence or config writing is being planned
- Lighthouse driver interaction or lighthouse_console usage is being discussed
- Tundra SiP integration or driver capabilities are being explored

## Scope Estimate

**Small** -- Research task only. Check Tundra SiP documentation, SDK, and driver behavior for IPD-related config write capabilities. If the feature exists, it simplifies Phase 13 significantly.

## Breadcrumbs

Related code and decisions found in the current codebase:

- `src/driver/device_provider.cpp` -- Current lighthouse_console.exe usage for config reading (ReadEyeToHeadRotation)
- `.planning/phases/11-core-ipd-pipe-command/11-CONTEXT.md` -- Phase 11 context references Tundra SiP as a research target
- `.planning/ROADMAP.md` -- Phase 13 (Slider Persistence) depends on lighthouse_console for config writes
- `.planning/REQUIREMENTS.md` -- SLIDER-03 (persist to headset lighthouse config via lighthouse_console)
- `.planning/PROJECT.md` -- Key decision: "EyeToHead rotation from lhr-* config by serial"

## Notes

Starting point for research: https://tundra-labs.com/products/tl448k6d-vr-system-in-package-for-steamvr-tracking

The Tundra SiP package should be well-documented online. Look for:
- SDK documentation mentioning IPD or eye_to_head config handling
- Driver source or API that writes to lighthouse config on property changes
- Any SteamVR driver hooks for config persistence
- Whether the SiP driver responds to VREvent_IpdChanged by updating its stored config