---
id: LSN-0053
ticket: studio-packer-rgba8888-asset-pipeline
title: RGBA8888 Is the Canonical Studio and Packer Palette Contract
created: 2026-07-14
tags:
  - studio
  - packer
  - assets
  - glyph-bank
  - palette
  - rgba8888
  - runtime-alignment
---

# RGBA8888 Is the Canonical Studio and Packer Palette Contract

### Original Problem

The runtime moved to RGBA8888 as the canonical logical color and framebuffer
format, but Studio and packer still treated glyph-bank palettes as RGB565-era
data. The old pipeline exposed `convertedRgb565`, preserved ARGB as normal
projected metadata, reserved palette index `0` for transparency, flattened or
discarded alpha semantics, and carried magenta color-key behavior as a hidden
transparency shortcut.

That made the asset pipeline ambiguous. A glyph-bank asset could look valid to
Studio while still carrying palette data that no longer matched the runtime
contract.

### Consolidated Decision

`GLYPH/indexed_v1` remains the runtime-facing format name and keeps its
indexed/paletized glyph-bank identity. The incompatible change is inside the
palette contract:

1. `rgba8888` is the canonical authored, projected, and emitted palette field.
2. RGBA8888 values are interpreted as `0xRRGGBBAA` in runtime channel order.
3. Java `BufferedImage` ARGB values are input-only host API details and must be
   converted deliberately at the packer boundary.
4. Palette index `0` is ordinary. Glyph palettes have 16 usable entries.
5. Transparency, including partial transparency, is represented only by alpha.
6. Magenta color-key behavior is not a normal Studio or packer feature.
7. RGB565 is not a compatibility path for runtime-facing glyph-bank palettes.

### Implementation Result

The packer specs now define glyph-bank palette metadata with `rgba8888`, and
the binary `GLYPH/indexed_v1` payload uses a `64 * 16 * 4 = 4096` byte palette
block instead of the old `64 * 16 * 2 = 2048` byte RGB565 block.

The packer palette model now carries canonical RGBA8888 values. Image import
converts Java ARGB pixels into runtime RGBA values before palette extraction,
and palette identity includes alpha. This allows transparent and partially
transparent colors to be distinct palette entries.

Packer read, detail, write, and cache paths now use `rgba8888` as the normal
metadata contract. Emission writes palette bytes in `R`, `G`, `B`, `A` order
and no longer emits a synthetic magenta entry for index `0`.

Tests and fixtures were updated to prove the new contract: RGBA channel order,
alpha preservation, 16 usable colors, index `0` as ordinary data, magenta as
ordinary color data, and 4096-byte palette blocks. Final validation confirmed
that remaining stale-looking references are either normative "not supported"
statements, historical discussion context, or explicitly out-of-scope generated
project cache data.

### Practical Pattern

When a host API exposes color in a different layout than the runtime contract,
name the boundary explicitly and keep the canonical field runtime-oriented.
For this pipeline:

- accept host ARGB only at import/read time;
- convert to RGBA8888 before storing palette metadata;
- project `rgba8888` to Studio and packer clients;
- emit RGBA bytes directly into `assets.pa`;
- convert back to UI-friendly ARGB only inside presentation code.

This keeps tooling convenient without letting host representation leak into the
runtime asset contract.

### Common Pitfalls and Anti-patterns

- Do not treat `originalArgb8888` as canonical pipeline data. ARGB can be a UI
  or image-input representation, but `rgba8888` owns the contract.
- Do not reintroduce `convertedRgb565` as a normal projected field or emitted
  payload. RGB565 compatibility was deliberately rejected for this path.
- Do not reserve palette index `0` for transparency. Alpha owns transparency.
- Do not use magenta as a hidden color key. A magenta RGBA value is just color
  data unless an explicit future import tool defines a separate conversion.
- Do not change scene `palette_id` semantics as part of color-format work.
  Scene records still reference glyph-bank palette indices.
- Do not fold `DSC-0005` variable palette-count work into RGBA8888 cleanup.
  Palette encoding changed here; palette-count optimization remains separate.

### References

- `DEC-0037`: Studio and Packer RGBA8888 Asset Pipeline Contract.
- `PLN-0081`: Packer and Studio spec propagation.
- `PLN-0082`: Palette model and ARGB conversion boundary.
- `PLN-0083`: Glyph payload emission and size accounting.
- `PLN-0084`: Packer projections and workspace APIs.
- `PLN-0085`: Tests, fixtures, and conformance updates.
- `PLN-0086`: Final integration and residue removal.
- `docs/specs/packer/3. Asset Declaration and Virtual Asset Contract Specification.md`.
- `docs/specs/packer/4. Build Artifacts and Deterministic Packing Specification.md`.
- `docs/specs/studio/4. Assets Workspace Specification.md`.