[HarryCordewener]

Why

Kitty supports alpha blending, but inline game images lost it before reaching the terminal: SharpConsoleUI's PixelBuffer drops alpha, and InlineImageHost then sent RGB24. Transparent and translucent regions therefore became opaque. Avalonia's existing encoded-PNG renderer already composites alpha correctly.

Changes

• Retain straight RGBA source pixels in the inline image cache rather than RGB-only PixelBuffer.
• Resize with premultiplied-alpha interpolation to avoid hidden colors bleeding around transparent edges.
• Send RGBA PNG through the existing Kitty TransmitImage API instead of RGB24.
• Keep the RGB pixel-buffer conversion for half-block/Sixel fallback consumers.
• Keep the existing restricted WebP-only ImageSharp decoder; TIFF remains rejected.

Verification

• Full Release solution build succeeds.
• Core, Client, Graphics, Scripting, Web and TUI suites pass.
• New end-to-end Avalonia tests load a PNG through InlineImageHost and the Kitty driver, render placeholder cells, and check actual composited pixels for alpha 0, 128 and 255.
• Transparent resize-edge test passes; PNG/WebP RGBA parity and malformed/TIFF rejection tests pass.
• Full Avalonia suite passes: 902 tests. Final targeted PictureRenderingTests pass: 12 tests. TUI final suite: 3017 tests.

Scope: inline game/MXP images. This does not add raw Kitty APC parsing or change the browser/web-view ImageControl path, and it does not promise alpha blending in Sixel/half-block fallback. No desktop visual session, merge or deployment performed.

Kitty protocol reference: https://sw.kovidgoyal.net/kitty/graphics-protocol/

[coderabbitai]

Caution

Review failed

The pull request is closed.

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