Export document frame faces as PNGs

docs/modernization/build-inventory.md

@@ -253,7 +253,8 @@ powershell -ExecutionPolicy Bypass -File scripts\automation\apple-remote-build.p
   opacity, and blend mode applied in document order, then uploading those six
   faces through the renderer-neutral `IRenderDevice` texture API using the
   recording backend. It also covers the shared recorded-upload report helper
-  consumed by CLI and live export-readiness bridges.
+  consumed by CLI and live export-readiness bridges, plus a pure six-face PNG
+  export helper that encodes composited document-frame faces through `pp_assets`.
 - `pano_cli simulate-document-export` exposes the same pure document-to-PPI
   export, asset-level decode, and document reimport path through JSON
   automation and is covered by `pano_cli_simulate_document_export_smoke`.
@@ -273,14 +274,16 @@ powershell -ExecutionPolicy Bypass -File scripts\automation\apple-remote-build.p
   snapshots also feed the active frame through the `pp_paint_renderer`
   document-frame compositor and renderer-neutral recorded-upload report helper,
   reporting texture, transition, command, byte, and active-frame payload counts
-  in `rendererUpload` JSON. It is covered by
+  in `rendererUpload` JSON. The same payload-complete path also reports
+  `facePngExport` readiness, face count, byte count, and payload count from the
+  pure face-PNG export helper. It is covered by
   `pano_cli_plan_canvas_document_snapshot_smoke` plus the payload-bearing
   snapshot smoke.
 - Live equirectangular, layer, animation-frame, and cube-face export adapters
   now prepare and log the same payload-bearing canvas document snapshot plus
-  shared renderer-neutral active-frame upload report before delegating to
-  retained `Canvas` export execution. Depth and video export remain on the older
-  retained path.
+  shared renderer-neutral active-frame upload and face-PNG export reports before
+  delegating to retained `Canvas` export execution. Depth and video export
+  remain on the older retained path.
 - `pano_cli save-document-project` writes that pure document export to a PPI
   file and is covered by `pano_cli_save_document_project_roundtrip_smoke`,
   which inspects and loads the generated file.

docs/modernization/capability-map.md

@@ -26,7 +26,7 @@ and validation command.
 | PNG/JPEG import | `Image`, `Canvas` import paths | `pp_assets`, `pp_document` | Fixture import, malformed file |
 | PNG/JPEG export | `Canvas`, `Image`, export dialogs | `pp_assets`, `pp_paint_renderer`, `pp_app_core` | Golden output tolerance, export start/target planning tests, live export-adapter document snapshot readiness |
 | Equirectangular import/export | `Canvas`, shaders, RTT, export dialogs | `pp_paint_renderer`, `pp_app_core` | Tiny cube/equirect golden, app-core file target tests, live export-adapter renderer-upload readiness |
-| Cube face export | `Canvas` | `pp_paint_renderer` | Pure six-face document frame composite, renderer texture-upload bridge, payload-complete canvas-snapshot renderer-upload automation, live export-adapter renderer-upload readiness, OpenGL command-plan coverage, six-face golden set |
+| Cube face export | `Canvas` | `pp_paint_renderer` | Pure six-face document frame composite, renderer texture-upload bridge, pure face-PNG export helper, payload-complete canvas-snapshot renderer-upload and face-PNG automation, live export-adapter renderer/export readiness, OpenGL command-plan coverage, six-face golden set |
 | Depth export | `Canvas`, grid tools | `pp_paint_renderer` | Float/readback validation |
 
 ## Brush And Painting

docs/modernization/roadmap.md

@@ -678,13 +678,18 @@ snapshots and reports generated byte/dirty-face summaries. The same automation
 now feeds payload-complete snapshots through the `pp_paint_renderer`
 document-frame compositor and renderer-neutral recording upload path, reporting
 texture, transition, byte, payload, and command counts through the shared
-`record_document_frame_upload` report helper. Live save writer replacement,
-export adoption, and renderer-owned readback remain under
+`record_document_frame_upload` report helper. Payload-complete snapshot
+automation also encodes the active document frame's six composited faces to PNG
+bytes through `pp_paint_renderer::export_document_frame_face_pngs`, giving the
+cube-face export path a pure renderer/document writer primitive before live
+writer replacement. Live save writer replacement, export adoption, and
+renderer-owned readback remain under
 `DEBT-0010`/`DEBT-0013`/`DEBT-0036`.
 Live equirectangular, layer, animation-frame, and cube-face export adapters now
 prepare the same payload-bearing document snapshot and renderer-neutral upload
-report helper before delegating to retained `Canvas` export execution, so export
-workflows consume the shared renderer boundary without changing file output yet.
+report helper plus pure face-PNG export report before delegating to retained
+`Canvas` export execution, so export workflows consume the shared renderer
+boundary without changing file output yet.
 `pano_cli plan-image-import` exposes app-core planning for File > Import image
 route decisions, including wide equirectangular images, legacy vertical cube
 strips, regular transform-placement images, and invalid image dimensions; live
@@ -2517,12 +2522,15 @@ Results:
   boundary now: `pano_cli plan-canvas-document-snapshot` records the same
   snapshot through the pure document-frame compositor and renderer-neutral
   texture upload stream through `pp_paint_renderer::record_document_frame_upload`,
-  so agents can validate document/canvas payloads moving into renderer commands
-  before live canvas export/save writer replacement.
+  and encodes the composited active-frame cube faces as PNG bytes through
+  `pp_paint_renderer::export_document_frame_face_pngs`, so agents can validate
+  document/canvas payloads moving into renderer commands and image bytes before
+  live canvas export/save writer replacement.
 - Live image/collection/cube export adapters now prepare and log the same
-  document/canvas plus shared renderer-upload readiness report before retained
-  `Canvas` export calls. Depth and video export remain on their prior retained
-  paths; actual image/cube writer replacement remains tracked under export debt.
+  document/canvas plus shared renderer-upload and face-PNG export readiness
+  reports before retained `Canvas` export calls. Depth and video export remain
+  on their prior retained paths; actual image/cube writer replacement remains
+  tracked under export debt.
 - Snapshot creation now rejects invalid embedded RGBA8 face payloads before
   document export or history can persist malformed state.
 - Package-smoke wrappers validate the Windows CMake app executable/runtime