# Idea Brief: HPT2 Personality Update Floor at 00-05-01

Status: exploring
Type: idea-brief
Updated: 2026-09-21
Next Action: plan SMI 00-05-01 implementation in this repository; bench transition testing remains paused
Readiness Review: run explicitly with ts: bs review; ordinary brainstorming does not review
Produces:

## Current Synthesis

### Idea

Release SMI 00-05-01 with a minimum compatibility floor that prevents an HPT2 unit from installing older FAT32-era personality firmware. Use the existing IMX header Title as the source of candidate family and version identity, together with MachineMask, layout, and CRC checks. The external USB filename may be changed by an operator and is not an identity input. No new header field is required. SMI accepts a FAT32 DisplayTest handoff, performs the unit's controlled HPT2 initialization, and has an approved return path to revised DisplayTest.

### Why It Matters

Controller B running older DisplayTest showed a persistent white screen with HPT2 media. It booted after the expendable card was formatted FAT32. A downgrade from HPT2 personality firmware to FAT32-era firmware could leave an installed controller without display access. Published SMI 00-05-00 supports HPT2 but does not have this guard; a new release is required.

### Desired Outcome

- SMI 00-05-01 identifies the candidate before any QSPI erase: bounded numeric version and family parsed from the validated IMX header Title, intended machine from MachineMask, and existing integrity/layout checks. Require the identity fields within the Title to be consistent. The external USB filename is used only to discover an `.imx` candidate; renaming it does not change acceptance.
- Admit recognized approved HPT2-capable SMI, CVO, or DVO personality images only at 00-05-01 or later. Reject older, unknown, inconsistent, or unparseable personality identities before erase and leave firmware bootable and SD media untouched.
- The common cutoff intentionally refuses reinstalling SMI 00-05-00, despite that release's HPT2 logger.
- Guarded SMI permits a return to explicitly approved revised DisplayTest 01-xx image(s). Revised DisplayTest boots safely with HPT2 media and tells the operator that normal production testing requires a FAT32 card. Its updater enforces the same personality minimum so the return path cannot bypass the floor. Older DisplayTest images are excluded from the normal return path.
- SMI accepts eligible FAT32 media from the DisplayTest fixture and initializes HPT2 only through an explicit service action with data-loss warnings, confirmations, card identity recheck, and disposition of required FAT32 history. Verify logging, retention, history, and export. Already ready HPT2 media is not needlessly reinitialized.
- Prove installation from old and revised FAT32 DisplayTest handoffs on both controller assemblies. Then prove renamed USB files with valid Titles remain eligible, legacy IMX images are rejected before erase without boot loss, and the approved revised DisplayTest return path boots safely with HPT2 media.

## Constraints And Non-Goals

- CVO and DVO 00-05-01 will need their own HPT2-capable builds and proof; this lane implements SMI only.
- DisplayTest uses a separate 01-xx version series. Name the exact revised release image(s) approved for return; unknown or older DisplayTest images default to refusal.
- MachineMask alone does not establish product identity or SD compatibility. The version convention depends on controlled release discipline, not cryptographic authentication.
- Preserve published IMX files unchanged. Do not erase card data requiring retention without controlled disposition.
- This brief authorizes no code change, build, programming, format, power cycle, bench test, release, or rollout. Transition testing is paused.

## Shared Transition Contract

- DisplayTest normal production testing and Prep for Ship hand off verified FAT32 media; separate card-family qualification remains HPT2.
- Personality releases SMI, CVO, and DVO 00-05-01 and later signify HPT2 support.
- SMI 00-05-01 owns the explicit FAT32-to-HPT2 initialization and personality minimum compatibility floor. Approved revised DisplayTest provides the guarded return path and safe HPT2-card startup.
- Use separate project-bound Codex VS Code lanes. Related DisplayTest brief: FAT32 Production SD Handoff and Separate HPT2 Qualification in E:\dev\high_point\7520708_DispTest_FW.

## Open Questions

- Which exact revised DisplayTest 01-xx release image(s) satisfy safe HPT2-card startup and the reciprocal personality floor, and may be installed from guarded SMI?
- Which exact released IMX specimens and target checks prove parsing, refusal before erase, and FAT32-to-HPT2 acceptance on both controller assemblies?

## Decisions

- Use existing IMX header information and the common 00-05-01 personality minimum.
- Treat the validated header Title as the source of family/version identity; do not require the external USB filename to match it.
- Permit return only to approved revised DisplayTest with safe HPT2-card startup and a reciprocal personality floor. Normal DisplayTest production handoff remains FAT32.
- Fail closed on unknown or inconsistent identity before erase.
- Fixture handoff remains FAT32; SMI performs explicit, warned HPT2 initialization after media identity and retention checks.
- Qualify the transition and refusal matrix on both controller assemblies, including renamed files, old and revised DisplayTest handoffs, SMI 00-05-00 refusal, and safe return to revised DisplayTest. Qualify CVO and DVO builds separately.
- Bench testing remains paused until the owner resumes it.

## Exploration Log

### 2026-09-21

- Owner selected a common 00-05-01 minimum for SMI, CVO, and DVO HPT2 personalities, directed the next SMI revision to be 00-05-01, and requested separate Tool Shed entry points.
- Owner accepted the transition and media-preparation recommendations, required a return path to DisplayTest, and selected the IMX header Title as the candidate identity source because operators may rename the external USB file. The recommended return path is approved revised DisplayTest with safe HPT2-card startup and a reciprocal personality floor; its exact release image remains to be named.
