diff --git a/HANDOFF.md b/HANDOFF.md
index 156496e..303a69f 100644
--- a/HANDOFF.md
+++ b/HANDOFF.md
@@ -1,52 +1,76 @@
-# HANDOFF — 2026-09-10 (transparency hardening applied)
+# HANDOFF — 2026-09-12 (transparency: ROOT CAUSE FOUND + FIXED, awaiting the verify take)
## Branch / Commit State
-`main` HEAD will be = the new transparency-hardening commit (slice 14). Ahead of
-origin by 19, NOT pushing (user ruling: no push until web-overlay transparency AND
-audio-silence are addressed).
+`main` HEAD lands THIS WORK UNIT: the compositor alpha fix (see ✅ below) + its ONE
+integration test + memory updates (`MyMistakes.md`, `ai.md`, `HANDOFF.md`). Ahead of
+origin by ~22 commits. **NOT pushing** — user ruling: no push until web-overlay
+transparency AND audio-silence are addressed. Nothing uncommitted at end of session.
-## ACTIVE THREAD (ONE problem at a time)
+## ✅ HONEST STATUS — THE TRANSPARENCY BUG IS IDENTIFIED
-**Web-uri transparency — second hardening applied (background-image wipe), awaiting take.**
-The 15:34 take: the recording's box interior is the widget's OWN full-canvas opaque paint
-(bright content strips at top/bottom + right bar over a black void) — NOT desktop, NOT a
-compositor blend. The real-document dumps showed blank-transparent at +1s and the page's
-backdrop appears later; a background-COLOR-only `!important` wipe (b4bba4b) leaves CSS
-background-IMAGE (gradient/backdrop) intact — the OBS answer is `background: none
-!important`, background-image too (obsproject/obs-studio#6659).
+**Root cause found by reading the unread code path to the end (the handoff's live
+suspect, now convicted):**
-**Slice 15 (commit target, the fix):**
-- `TransparentBackgroundScript` now also wipes `background-image:none!important` on
- `html,body,html *` (gradients/backdrops die; `
`/DOM art survives — OBS semantics).
-- `NavigateCompleted` re-arms `WidgetDumpRemaining = 5` ~30s in, so this take dumps the
- real document INSIDE the recording window (the missing evidence last time).
-- Test extended (asserts `background-image:none!important` present, weak inline form absent).
+`SceneCompositor.BlitContentRaw` (SceneCompositor.cs, partial-alpha `else if (sa > 0)`
+branch) applied the OPAQUE-dst source-over blend onto the paste-cache raster's
+TRANSPARENT base: `dst = (src*sa + dst*inv)/255` with dst black → color premultiplied by
+sa, then `dst[+3] = 255`. A 50%-alpha widget pixel became darkened color + FULL alpha; at
+paste time `BlendRowOpaque` saw alpha 255 → straight copy → the scene behind was
+overwritten by darkened ink. Transparent margins (alpha 0) and opaque content (alpha 255)
+survived, which is why every take showed a box while the dumps (raw capture) and the
+preview (raw WriteableBitmap) stayed correct. The CSS-wipe fixes (`b4bba4b`/`0f72c53`)
+were red herrings — they treated the PAGE as the villain, but the capture was transparent
+from the start (the 15:51 dumps already proved it).
-## THE ONE REMAINING STEP (verify, no further analysis)
+**The fix (committed):** `BlitContentRaw` gained `transparentDst=false`; the raster call
+passes `true` and writes straight color + straight alpha so the paste rows
+(`BlendRowOpaque`/`BlendRowWeighted`) do the real source-over onto the opaque master.
+The two blend rows were verified correct all along (HANDOFF accepted facts held); the
+divergence was the sampler feeding them. Master paths are bit-identical (`transparentDst`
+defaults false).
-1. User records the Live scene, widget animating (pre-record ~35s so the 30s re-arm dump
- fires mid-take).
-2. Verdict: element rect shows the scene backdrop behind the widget art (no black box/void)
- → transparency CLOSED, push gate #1 clears. If a black void persists BEYOND a visible
- background-image, it's not background painting and only chroma-key remains — bring the
- take and we do the compositor key, not more capture investigation.
-3. Then the queued layer-order-save bug (reorder doesn't persist `SortOrder`) is next.
+**Verification:** clean build 0 warnings (app + tests); `SceneCompositorTests` +
+`SceneGraphTests` + `FramePumpTests` + `ChatOverlayLayerCacheTests` = 22 pass, the ONE
+failure is the documented pre-existing `Composite_FullScene_MasterPixels` pixel (1380,700)
+(reproduces with the fix stashed — see ai.md slice 9). The new
+`PasteCache_SemiTransparentLayer_RevealsBackdrop_NotOpaqueInk` test FAILS on the old code
+(exact signature: `pixel (16,16): expected rgb(127,0,128), got rgb(0,0,128)`) and PASSES
+on the fix — non-vacuous, proven both ways.
+
+## NEXT STEP — ONE take (verify, no further analysis)
+
+The Good Dog Rule is satisfied (ONE integration test shipped with the fix). Record the
+Live scene with the widget animating, pre-record ~35s so the 30s re-arm dump fires
+mid-take, then read the verdict:
+- Element rect shows the scene backdrop behind the widget art (no black box/void, no
+ darkened edge ring) → **transparency CLOSED, push gate #1 clears**.
+- If anything persists, the fix's own test contract is the diagnostic: a translucent
+ pixel must read as scene-through-src, never inked — bring the take.
## Other threads (paused)
-- **Audio silence** — `f3d578c` has per-5s `Audio live:` telemetry; next take with desktop
- audio ACTIVE names the stage. Push gate #2.
+- **Audio silence** — `f3d578c` has per-5s `Audio live:` telemetry; next take with
+ desktop audio ACTIVE names the stage. Push gate #2.
- **Webcam missing** — "MJPG negotiation refused (being used by another process)". Queued.
- **Web capture speed** — ~10-14Hz effective, user satisfied. Revisit only on request.
+- **Layer order** — dragging an element over another does not persist `SortOrder`; user
+ explicitly asked it not be buried. Queued after transparency.
+- **Known backfills when queued work resumes:** `Composite_FullScene_MasterPixels` pixel
+ (1380,700) cyan-vs-magenta (pre-existing, recorded in ai.md slice 9); vertical-tier
+ `BilinearScale` fresh allocation per frame.
## Landmines
- testhost shares startup.log with the app — filter by time.
-- App was running at commit time; `taskkill //F //IM ytLive.exe` (Windows `taskkill.exe`,
- bash-quoted `//F //IM`) before rebuilds, and re-run if `MSB3021` copy-lock appears.
-- Build/tests: `/mnt/c/Program Files/dotnet/dotnet.exe build …` / vstest.
-- Probing: `/mnt/c/Program Files/Krita (x64)/bin/ffmpeg.exe` / `ffprobe.exe` — Windows exes
- take Windows-style paths.
-- Never re-derive the transparency story again — MyMistakes "SPIN GUARD → RESOLVED" is the
- record (wash-rinse-repeat cost the user a whole session).
\ No newline at end of file
+- `taskkill //F //IM ytLive.exe` before rebuilds; re-run if `MSB3021` copy-lock.
+- Build/tests: `/mnt/c/Program Files/dotnet/dotnet.exe build …` / vstest. 0 warnings rule.
+ FULL-suite vstest can hang (WASAPI teardown, pre-existing) — per-class filters are the
+ norm (`--TestCaseFilter:"FullyQualifiedName~…"`).
+- Probing: `/mnt/c/Program Files/Krita (x64)/bin/ffmpeg.exe` / `ffprobe.exe` — Windows
+ exes take Windows-style paths (do NOT re-download Linux ffmpeg — user aborted that).
+- Evidence artifacts (keep): `%TEMP%\ytLive-web-8d7234ec-…-w1..5.png` (15:51),
+ recordings `ty-20260910-12\51|1534|1551-*.mp4`, decoded frames at
+ `/mnt/c/Users/gramp/AppData/Local/Temp/w151.raw`.
+- The full transparency story lives in `MyMistakes.md` → "SPIN GUARD → RESOLVED" (now
+ including the 2026-09-12 RESOLVED entry). GREP IT FIRST. Do not re-derive a fourth time.
\ No newline at end of file
diff --git a/MyMistakes.md b/MyMistakes.md
index 62a6525..83bd230 100644
--- a/MyMistakes.md
+++ b/MyMistakes.md
@@ -93,6 +93,29 @@ closes. Self-inflicted again: the agent re-derived the whole transparency story
this entry — the instrument said transparent because the capture had NOT been
repainted yet. Do NOT re-derive this story a third time.
+**2026-09-12 → RESOLVED — the box lived in the paste-cache RASTER, not the page.**
+The 15:51 facts (alpha max=255, mean ~19, zero 57%, white rounded panel, real
+transparent margins) + preview-correct + recording-box meant the capture transparency was
+REAL all along; the fracture sat in `SceneCompositor.BlitContentRaw`
+(SceneCompositor.cs:419-550) — the sampler that builds the element-space paste-cache
+raster, the ONE path the take loop never read in full. Its partial-alpha branch applied
+the OPAQUE-dst blend onto a TRANSPARENT raster base: `dst = (src*sa + dst*inv)/255`
+with dst black → color PREMULTIPLIED by sa, then `dst[+3] = 255` — a 50%-alpha widget
+pixel became darkened color + FULL alpha. At paste time `BlendRowOpaque` saw alpha 255 →
+straight copy → the scene behind was overwritten by darkened ink. Fully-transparent
+margins (alpha 0, `continue`) and fully-opaque content (alpha 255 branch) survived —
+which is why every take showed a box while the dumps and the preview (raw WriteableBitmap,
+unaffected by the compositor) stayed correct, and why the CSS-wipe fixes (`b4bba4b` /
+`0f72c53`) were red herrings: they treated the page as the villain, but the capture was
+transparent from the start. **FIX:** `BlitContentRaw` gained `transparentDst=false`;
+the raster call site passes `true` and writes STRAIGHT color + straight alpha so the
+paste rows (`BlendRowOpaque`/`BlendRowWeighted`) do the real source-over onto the opaque
+master. The master paths are untouched (bit-identical). ONE test
+`PasteCache_SemiTransparentLayer_RevealsBackdrop_NotOpaqueInk` fails on the old code with
+exactly the bug encoded: 50%-blue over red reads `(0,0,128)` instead of `(127,0,128)` —
+backdrop never shows through. Next: verify take (element rect shows the backdrop behind
+the widget art), then push gate #1 clears.
+
### Shrink / re-encode an image for the README (screenshots → small hero image)
Worked out 2026-08-29 (the recipe was NEVER recorded the first time it was done, so
diff --git a/Services/Compositor/SceneCompositor.cs b/Services/Compositor/SceneCompositor.cs
index 06f6dab..85cf29a 100644
--- a/Services/Compositor/SceneCompositor.cs
+++ b/Services/Compositor/SceneCompositor.cs
@@ -308,7 +308,7 @@ public sealed class SceneCompositor
}
if (raster == null) raster = new VideoFrame(dw, dh, new byte[dw * dh * 4]);
Array.Clear(raster.BgraPixels);
- BlitContentRaw(raster.BgraPixels, dw, dh, 0, 0, ew, eh, frame, 1f, isRound, mirror);
+ BlitContentRaw(raster.BgraPixels, dw, dh, 0, 0, ew, eh, frame, 1f, isRound, mirror, transparentDst: true);
lock (_pasteGate)
{
// Only the SOURCE frame's identity is a real key owner; drop any older
@@ -419,7 +419,8 @@ public sealed class SceneCompositor
private static void BlitContentRaw(
byte[] dst, int dstW, int dstH,
float ex, float ey, float ew, float eh,
- VideoFrame src, float opacity, bool isRound, bool isMirror)
+ VideoFrame src, float opacity, bool isRound, bool isMirror,
+ bool transparentDst = false)
{
if (ew <= 0 || eh <= 0) return;
@@ -529,11 +530,27 @@ public sealed class SceneCompositor
}
else if (sa > 0)
{
- var inv = 255 - sa;
- dst[di] = (byte)((sb * sa + dst[di] * inv + 127) / 255);
- dst[di + 1] = (byte)((sg * sa + dst[di + 1] * inv + 127) / 255);
- dst[di + 2] = (byte)((sr * sa + dst[di + 2] * inv + 127) / 255);
- dst[di + 3] = 255;
+ if (transparentDst)
+ {
+ // Element-raster pass on a TRANSPARENT base (the paste cache):
+ // keep straight color + straight alpha so the paste rows can
+ // source-over onto the opaque master. Premultiplying here (the
+ // opaque-dst blend) stamped alpha 255 onto already-alpha-scaled
+ // color — the paste over-wrote the scene with darkened ink, the
+ // web widget's "black box" in recordings.
+ dst[di] = (byte)sb;
+ dst[di + 1] = (byte)sg;
+ dst[di + 2] = (byte)sr;
+ dst[di + 3] = (byte)sa;
+ }
+ else
+ {
+ var inv = 255 - sa;
+ dst[di] = (byte)((sb * sa + dst[di] * inv + 127) / 255);
+ dst[di + 1] = (byte)((sg * sa + dst[di + 1] * inv + 127) / 255);
+ dst[di + 2] = (byte)((sr * sa + dst[di + 2] * inv + 127) / 255);
+ dst[di + 3] = 255;
+ }
}
}
}
diff --git a/ai.md b/ai.md
index 321429a..97d53bd 100644
--- a/ai.md
+++ b/ai.md
@@ -758,7 +758,13 @@ seam:** `Func`, `Func` resolver, `FuncTHE page-transparency fix (the web widget's recording "black box"): a
+ /// semi-transparent layer flowing through the paste-cache raster must reveal the
+ /// backdrop through it (true source-over), never an opaque darkened block. The raster
+ /// is built on a TRANSPARENT base, but the old partial-alpha branch applied the
+ /// opaque-dst blend (premultiplied color + forced alpha 255), so every translucent
+ /// widget pixel pasted as opaque ink — the box in recordings while the raw-bitmap
+ /// preview stayed correct. A half-alpha blue widget over a red backdrop must read
+ /// (127,0,128) here; the buggy raster pastes (0,0,128).
+ [Fact]
+ public void PasteCache_SemiTransparentLayer_RevealsBackdrop_NotOpaqueInk()
+ {
+ var red = Solid(128, 64, 255, 0, 0); // live backdrop
+ var web = new byte[32 * 16 * 4]; // 2:1 widget canvas, half-alpha blue, uniform
+ for (var i = 0; i < web.Length; i += 4)
+ {
+ web[i] = 255; web[i + 1] = 0; web[i + 2] = 0; web[i + 3] = 128;
+ }
+ var semitransparent = new VideoFrame(32, 16, web); // NOT IsOpaque
+
+ var background = new Source { Type = SourceType.DisplayCapture, IsBackground = true, CaptureKey = "monitor:0" };
+ var widget = new Source { Type = SourceType.WebSource, X = 8, Y = 8, Width = 16, Height = 16 };
+ var scene = new Scene { Name = "Live" };
+ scene.Elements.Add(background);
+ scene.Elements.Add(widget);
+
+ VideoFrame? FrameFor(SceneElement e) => e switch
+ {
+ Source { IsBackground: true } => red,
+ Source { Type: SourceType.WebSource } => semitransparent,
+ _ => null,
+ };
+
+ var options = new CompositorOptions
+ {
+ SourceRectX = 0, SourceRectY = 0, SourceRectWidth = 128, SourceRectHeight = 64,
+ OutputWidth = 128, OutputHeight = 64,
+ };
+
+ var compositor = new SceneCompositor();
+ var build = compositor.Render(scene, FrameFor, null, options); // raster build + paste
+ var hit = compositor.Render(scene, FrameFor, null, options); // paste-cache hit
+ foreach (var output in new[] { build, hit })
+ {
+ AssertColor(output, 16, 16, 127, 0, 128); // backdrop shows through the 50% blue
+ AssertColor(output, 4, 4, 255, 0, 0); // outside the element: untouched backdrop
+ }
+ Assert.Equal(build.BgraPixels, hit.BgraPixels);
+ }
+
/// take-16 regression gate — GC churn convicted mechanically: a ring-style
/// producer hands out a small set of rotating arrays with a NEW EPOCH every frame
/// (exactly what the capture/camera rings do). The compositor must re-rasterize INTO