DX6/7 palette alpha and source-key contract — 2026-10-28

D3D-ALPHA-KEY-PRECEDENCE-20261014 remains unresolved. No new final-pixel expected-case fixture is justified. This bounded source investigation recovered versioned Microsoft SDK text, but no inspected passage explicitly defines simultaneous DDPCAPS_ALPHA palette use and COLORKEYENABLE. No renderer, tests, runtime, or main branch changed.

Base: 98d132898c963790f797ef3d00c812964e413cab. Reused TODOS.md task at line 11042, both October 14 reports (20261014-legacy-key-filter-contract and 20261014-palette-alpha-render), and b41362285b9f4973da64c60945316c90571955ca:docs/re-notes/d3d-alpha-key-contract-20261020.md through read-only donor objects. Their renderer characterization and native observation plan were not rerun.

Source identity and limits

Sources below are Microsoft-authored SDK text hosted by a third-party mirror, not independent third-party technical interpretations. The DX6 legal page identifies DirectX 6.1 Programmer's Reference, copyright 1997–1999, and warns that some development documentation may be inaccurate. The DX7 legal page identifies DirectX 7.0 Programmer's Reference, copyright 1995–1999. Inspected DX7 reference pages carry a September 2, 1999 build footer. The mirror's 2024 HTTP modification dates describe hosting, not API publication. No original CHM/package signature or authenticated SDK distribution was recovered; these are attributable period-text copies with that provenance limitation.

All direct retrievals used certificate verification, identity content encoding, declared-length and streamed-body caps (2 MiB per response, 16 MiB aggregate). Access date: 2026-10-28 UTC. Exact URL, access timestamp, response size, SHA-256, and failed requests are retained in the canonical receipt's evidence/sources/fetches.jsonl; raw HTML and derived text are retained separately. The source identity table below hashes the raw retrieved HTML, not search snippets or extracted text.

Findings mapped to inspected passages

The render-state reference's COLORKEYENABLE paragraph contradicts itself: it first limits effects to textures created with DDSD_CKSRCBLT, then says textures without that flag exhibit effects. The standalone Color Keying State pages explicitly say they do not. This inconsistency exists in both retrieved versions; it is not silently corrected or used to derive an alpha-palette exception. A separate check of source-key creation versus later SetColorKey would be needed before extending this wording beyond the controlled creation path.

Inference boundary: combining an alpha-palette definition with a generic statement that matching texels are omitted does not settle whether palette alpha makes the texture exempt from keying. The existing NVIDIA Color Key in Direct3D evidence distinguishes alpha-bearing textures, but never explicitly includes DDPCAPS_ALPHA palettes. That prior evidence is reused, not newly confirmed. Modern Microsoft capability pages, D3D9 advice, headers, Wine, and current renderer behavior supply no missing version-specific authority here.

Required observation before an expected-case fixture

Reuse the October 20 native matrix, separately on original DX6 interfaces and Device7, on an authorized OS/runtime/driver/device supporting alpha palettes. Record identities, texture-format enumeration, palette flags/attachment, caps, HRESULTs, key creation and read-back states. Unsupported formats are not precedence observations.

Use point sampling at interior centers, one stage selecting texture RGB/alpha, no mixed taps/fog/specular/stencil. Set low=high=7 at creation. Indices 7 and 8 share RGB but independently sweep alpha 0, 1, 64, 127, 128, 255; add ordinary-palette controls and a nonkey whose RGB equals the raw key integer. Toggle keying. Compare alpha test disabled, ALWAYS, GREATER 0, GREATER 127, plus a later-stage alpha-255 override; blending disabled versus SRCALPHA/INVSRCALPHA over known color; passing depth with writes on/off. Record color and depth separately, using readback or an independently validated farther-geometry occlusion probe.

The exact unresolved outputs remain: does key 7 preserve, replace, or bypass palette alpha; do nonkey low-alpha fragments survive when the application would accept them; can an alpha override restore a keyed fragment; and does unchanged blended color still permit depth writes? State144/filter defaults remain outside this task. No native run is authorized or claimed.

Negative search boundary and validation

Research stopped after this bounded SDK-page examination, not after exhausting the internet. General web searches covered DDPCAPS_ALPHA with color key/keying/COLORKEYENABLE, alpha palettes, and NVIDIA terminology. Targeted mirror title searches covered render-state types, alpha, palettes, textures, transparency, and color, then inspected the relevant pages above. Additional inspected DX6 pages on palette types and key setting add no precedence statement; compressed-texture alpha pages concern another format and were excluded. Search results involving Wine, wrappers, books, or later APIs were not promoted to normative evidence.

Preserved retrieval failures: DX6 Color Key title query closed its connection; DX7 Color title query failed; the obsolete DX6 alpha-state path under DX7 returned 404 (the actual DX7 alpha-testing/blending titles were then located); TDx Library's claimed verbatim DX7 reference failed TLS certificate verification. No trust weakening or unchanged denial retry occurred. No entire SDK/archive or tools were downloaded.

Validation checked every cited URL against retained bytes, versions/context against the legal pages and interface names, source hashes and locations, the one-path documentation delta, and git diff --check. This is documentary validation, not conformance testing. The canonical receipt records no new decisive precedence evidence and explicit remaining gates. Previous receipts remain unchanged.

Retrieved source identities