implements PLN-0071

crates/host/prometeu-host-desktop-winit/src/runner.rs

@@ -5,7 +5,7 @@ use crate::input::HostInputHandler;
 use crate::log_sink::HostConsoleSink;
 use crate::overlay::{capture_snapshot, draw_overlay};
 use crate::stats::HostStats;
-use crate::utilities::draw_rgb565_to_rgba8;
+use crate::utilities::draw_rgba8888_to_rgba8;
 use pixels::wgpu::PresentMode;
 use pixels::{Pixels, PixelsBuilder, SurfaceTexture};
 use prometeu_drivers::AudioCommand;
@@ -285,7 +285,7 @@ impl ApplicationHandler for HostRunner {
                     // Immutable borrow of prometeu-core (different field, ok)
                     let src = self.hardware.gfx.front_buffer();
 
-                    draw_rgb565_to_rgba8(src, frame);
+                    draw_rgba8888_to_rgba8(src, frame);
 
                     if let Some(snapshot) = overlay_snapshot.as_ref() {
                         draw_overlay(frame, Hardware::W, Hardware::H, snapshot);

crates/host/prometeu-host-desktop-winit/src/utilities.rs

@@ -1,26 +1,25 @@
-/// Copies RGB565 (u16) -> RGBA8888 (u8[4]) to the pixels frame.
+/// Copies RGBA8888 pixels in canonical RGBA raw order into the `pixels` RGBA8 frame.
-/// Pixels format: RGBA8.
+pub fn draw_rgba8888_to_rgba8(src: &[u32], dst_rgba: &mut [u8]) {
-pub fn draw_rgb565_to_rgba8(src: &[u16], dst_rgba: &mut [u8]) {
     for (i, &px) in src.iter().enumerate() {
-        let (r8, g8, b8) = rgb565_to_rgb888(px);
         let o = i * 4;
-        dst_rgba[o] = r8;
+        dst_rgba[o] = ((px >> 24) & 0xFF) as u8;
-        dst_rgba[o + 1] = g8;
+        dst_rgba[o + 1] = ((px >> 16) & 0xFF) as u8;
-        dst_rgba[o + 2] = b8;
+        dst_rgba[o + 2] = ((px >> 8) & 0xFF) as u8;
-        dst_rgba[o + 3] = 0xFF;
+        dst_rgba[o + 3] = (px & 0xFF) as u8;
     }
 }
 
-/// Expands RGB565 to RGB888 (high bit replication).
+#[cfg(test)]
-#[inline(always)]
+mod tests {
-pub fn rgb565_to_rgb888(px: u16) -> (u8, u8, u8) {
+    use super::draw_rgba8888_to_rgba8;
-    let r5 = ((px >> 11) & 0x1F) as u8;
-    let g6 = ((px >> 5) & 0x3F) as u8;
-    let b5 = (px & 0x1F) as u8;
 
-    let r8 = (r5 << 3) | (r5 >> 2);
+    #[test]
-    let g8 = (g6 << 2) | (g6 >> 4);
+    fn draw_rgba8888_to_rgba8_preserves_channel_order_and_alpha() {
-    let b8 = (b5 << 3) | (b5 >> 2);
+        let src = [0x12345678, 0xABCDEF01];
+        let mut dst = [0; 8];
 
-    (r8, g8, b8)
+        draw_rgba8888_to_rgba8(&src, &mut dst);
+
+        assert_eq!(dst, [0x12, 0x34, 0x56, 0x78, 0xAB, 0xCD, 0xEF, 0x01]);
+    }
 }

discussion/index.ndjson

@@ -35,4 +35,4 @@
 {"type":"discussion","id":"DSC-0032","status":"done","ticket":"system-os-lifecycle-process-task-contract","title":"Agenda - SystemOS Lifecycle, Process and Task Contract","created_at":"2026-05-14","updated_at":"2026-05-15","tags":["runtime","os","lifecycle","process","task","shell","firmware"],"agendas":[],"decisions":[],"plans":[],"lessons":[{"id":"LSN-0041","file":"discussion/lessons/DSC-0032-system-os-lifecycle-process-task-contract/LSN-0041-systemos-lifecycle-authority.md","status":"done","created_at":"2026-05-15","updated_at":"2026-05-15"}]}
 {"type":"discussion","id":"DSC-0033","status":"done","ticket":"system-os-service-ownership-and-module-layout","title":"Agenda - SystemOS Service Ownership and Module Layout","created_at":"2026-05-14","updated_at":"2026-05-15","tags":["runtime","os","services","module-layout","vm","window-manager","logging"],"agendas":[],"decisions":[],"plans":[],"lessons":[{"id":"LSN-0042","file":"discussion/lessons/DSC-0033-system-os-service-ownership-and-module-layout/LSN-0042-systemos-service-ownership-boundary.md","status":"done","created_at":"2026-05-15","updated_at":"2026-05-15"}]}
 {"type":"discussion","id":"DSC-0036","status":"done","ticket":"prometeu-hub-ui-direction","title":"Agenda - Prometeu Hub UI Direction","created_at":"2026-05-15","updated_at":"2026-05-22","tags":["hub","ui","shell","system-apps","lifecycle","design-system"],"agendas":[],"decisions":[],"plans":[],"lessons":[{"id":"LSN-0045","file":"discussion/lessons/DSC-0036-prometeu-hub-ui-direction/LSN-0045-hub-ui-slices-should-prove-os-boundaries.md","status":"done","created_at":"2026-05-22","updated_at":"2026-05-22"}]}
-{"type":"discussion","id":"DSC-0037","status":"in_progress","ticket":"rgba8888-framebuffer-and-pixel-format-direction","title":"Agenda - RGBA8888 Framebuffer and Pixel Format Direction","created_at":"2026-05-22","updated_at":"2026-05-23","tags":["gfx","framebuffer","rgb565","rgba8888","renderer","assets","host","backend"],"agendas":[{"id":"AGD-0037","file":"AGD-0037-rgba8888-framebuffer-and-pixel-format-direction.md","status":"accepted","created_at":"2026-05-22","updated_at":"2026-05-23"}],"decisions":[{"id":"DEC-0029","file":"DEC-0029-rgba8888-runtime-pixel-format-contract.md","status":"accepted","created_at":"2026-05-23","updated_at":"2026-05-23","ref_agenda":"AGD-0037"}],"plans":[{"id":"PLN-0067","file":"PLN-0067-rgba8888-published-contracts-and-specs.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0068","file":"PLN-0068-rgba8888-color-type-hal-and-abi-surface.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0069","file":"PLN-0069-rgba8888-cpu-renderer-and-composition.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0070","file":"PLN-0070-rgba8888-asset-palettes-tooling-and-fixtures.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0071","file":"PLN-0071-rgba8888-host-presentation-path.md","status":"open","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0072","file":"PLN-0072-rgba8888-residue-removal-and-end-to-end-validation.md","status":"open","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]}],"lessons":[]}
+{"type":"discussion","id":"DSC-0037","status":"in_progress","ticket":"rgba8888-framebuffer-and-pixel-format-direction","title":"Agenda - RGBA8888 Framebuffer and Pixel Format Direction","created_at":"2026-05-22","updated_at":"2026-05-23","tags":["gfx","framebuffer","rgb565","rgba8888","renderer","assets","host","backend"],"agendas":[{"id":"AGD-0037","file":"AGD-0037-rgba8888-framebuffer-and-pixel-format-direction.md","status":"accepted","created_at":"2026-05-22","updated_at":"2026-05-23"}],"decisions":[{"id":"DEC-0029","file":"DEC-0029-rgba8888-runtime-pixel-format-contract.md","status":"accepted","created_at":"2026-05-23","updated_at":"2026-05-23","ref_agenda":"AGD-0037"}],"plans":[{"id":"PLN-0067","file":"PLN-0067-rgba8888-published-contracts-and-specs.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0068","file":"PLN-0068-rgba8888-color-type-hal-and-abi-surface.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0069","file":"PLN-0069-rgba8888-cpu-renderer-and-composition.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0070","file":"PLN-0070-rgba8888-asset-palettes-tooling-and-fixtures.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0071","file":"PLN-0071-rgba8888-host-presentation-path.md","status":"done","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]},{"id":"PLN-0072","file":"PLN-0072-rgba8888-residue-removal-and-end-to-end-validation.md","status":"open","created_at":"2026-05-23","updated_at":"2026-05-23","ref_decisions":["DEC-0029"]}],"lessons":[]}

discussion/workflow/plans/PLN-0071-rgba8888-host-presentation-path.md

@@ -2,7 +2,7 @@
 id: PLN-0071
 ticket: rgba8888-framebuffer-and-pixel-format-direction
 title: RGBA8888 Host Presentation Path
-status: open
+status: done
 created: 2026-05-23
 ref_decisions: [DEC-0029]
 tags: [gfx, framebuffer, rgb565, rgba8888, renderer, assets, host, backend]