prometeu-runtime/discussion/workflow/plans/PLN-0169-asset-decode-validation-for-variable-glyph-palettes.md

id	ticket	title	status	created	ref_decisions	tags
PLN-0169	runtime-owned-variable-glyph-bank-palette-protocol	Asset Decode Validation for Variable Glyph Palettes	open	2026-07-14	DEC-0041	runtime assets glyph-bank decode validation

Briefing

DEC-0041 changes glyph-bank decode from a fixed 4096-byte palette block to a variable palette_count * 16 * 4 block. The asset manager is the runtime gate that must reject malformed glyph payloads before residency.

Decisions de Origem

• DEC-0041 - Variable Glyph Bank Palette Protocol

Alvo

Update glyph asset layout validation and decode to accept palette_count in 1..=64 and materialize exactly that many palettes.

Escopo

• Update crates/console/prometeu-drivers/src/asset.rs.
• Replace exact palette_count == 64 validation.
• Replace fixed GLYPH_BANK_PALETTE_BYTES_V1 usage in decode.
• Validate size and decoded_size using variable formulas.
• Read exactly palette_count * 16 * 4 bytes.
• Preserve RGBA byte order.

Fora de Escopo

• HAL storage changes except as required by PLN-0168.
• Composer invalid-reference behavior.
• Packer output changes.

Plano de Execucao

Step 1 - Change layout return data

What: Carry palette count through layout validation.

How: Update decode_glyph_bank_layout to return palette_count and palette byte count along with tile size, dimensions, and serialized pixel byte count.

Files: crates/console/prometeu-drivers/src/asset.rs

Step 2 - Replace exact palette-count validation

What: Accept only the DEC-0041 range.

How: Reject palette_count = 0 and palette_count > 64; accept all values in 1..=64.

Files: crates/console/prometeu-drivers/src/asset.rs

Step 3 - Use variable size formulas

What: Align entry validation with the spec.

How: Compute palette_bytes = palette_count * 16 * size_of::<u32>(), serialized_size = packed_pixels + palette_bytes, and decoded_size = logical_pixels + palette_bytes.

Files: crates/console/prometeu-drivers/src/asset.rs

Step 4 - Decode variable palette data

What: Read only materialized palettes.

How: In buffer and reader decode paths, slice/read exactly palette_bytes. Populate the new variable GlyphBank palette representation in order.

Files: crates/console/prometeu-drivers/src/asset.rs

Step 5 - Remove fixed-byte assumptions

What: Retire the fixed payload block from active decode.

How: Replace helper functions and tests that assume GLYPH_BANK_PALETTE_BYTES_V1 is always in the payload. Keep a maximum constant only if it is named as a maximum, not a payload size.

Files: crates/console/prometeu-drivers/src/asset.rs

Criterios de Aceite

• Decode accepts valid palette_count values from 1 through 64.
• Decode rejects palette_count = 0.
• Decode rejects palette_count > 64.
• size and decoded_size validation use variable palette bytes.
• Buffer and reader decode paths behave consistently.
• RGBA channel order remains unchanged.

Tests / Validacao

• Add unit tests for palette_count = 1, an intermediate count, and 64.
• Add rejection tests for 0, 65, short palette data, oversized metadata size, and mismatched decoded_size.
• Run the crate tests that cover asset manager glyph decode.

Riscos

• Existing tests may use generated glyph payload helpers with fixed 64-palette size.
• Reader and buffer paths can drift if only one path receives the variable-size change.