diff --git a/docs/research/2026-09-01-overhaul/476-capture-lifetime-diagnosis.md b/docs/research/2026-09-01-overhaul/476-capture-lifetime-diagnosis.md
index dc91ce20b..e67e90960 100644
--- a/docs/research/2026-09-01-overhaul/476-capture-lifetime-diagnosis.md
+++ b/docs/research/2026-09-01-overhaul/476-capture-lifetime-diagnosis.md
@@ -88,3 +88,51 @@ No #476 implementation is authorized by this diagnostic note. The lead will
 commit a bounded contract and dispatch one implementer after #475, with both
 review lenses and the campaign's normal gate/ledger rules. C1c, the geometry
 witness, full lanes, C2 and owner G4 remain outstanding; never merge main.
+
+## Additional lead static checks while #475 tests are corrected
+
+No #476 implementation was started. The lead read the complete real outer
+frame transaction, private renderer, capture controller and GPU frame adapter.
+The existing `IPrivateFrameScreenshot` is already a narrow capture seam;
+moving its invocation does not require a second GPU-frame owner. Preserve
+GPU measurement closure before GPU submission, and exactly one attempted
+frame close on every successful Begin, including render/recovery/close errors.
+The actual adapter clears CurrentFrame before calling its End.
+
+Post-screenshot consumers inspected: RenderFrameDiagnosticsController is
+CPU diagnostics; WorldLifecycleAutomationController reads borrowed world/
+reveal/resource snapshots and writes checkpoint JSON; the shadow comparison
+reads the completed CPU render oracle and clears its own dirty markers.
+None of these bodies requires an open GPU command frame. Their mutual order
+(capture, diagnostics, shadow comparison, lifecycle checkpoint) still matters.
+Do not move world/private draw phases or introduce another frame tick.
+
+Vulkan retention is explicitly opt-in. ConfigureBackbufferCapture creates
+the buffer only when `_retainBackbufferCapture` is true; retain that default-
+off cost. RecordBackbufferCapture records the copy while the swapchain image
+is acquired, then QueueSubmit2 submits it. A validity marker must reflect an
+actually submitted copy, not merely allocation or command recording; resize,
+failed submission and skipped/zero-area frames must not label old/uninitialized
+bytes as the newly requested complete frame. The bring-up caller already
+reads after ending its frame.
+
+Named retail's screenshot boundary was also checked statically against the
+same paired executable SHA256006FFEADC5D679C871497112A5BD1F87714D0E273E2166BAE5052DDE369297B1:
+
+| Function/window | Length | SHA256 |
+|---|---:|---|
+| Device::GetScreenshotSurface00439160, complete body |298|7717277646A9283ECBD10594177A5EC70213194E19B8F61BBC587C20BC3A7907|
+| Device::SaveScreenshot0043A540, initial call window |32|00C51A0CD7CCA7D4C8075352BDA05683B196516604719243D01C349B4C408B4A|
+| RenderDeviceD3D::GenerateSurfaceFromFrontBuffer005A0210, complete body |105|BA36CC608770994E60F9566C36D269160AE4936765CAD103DAF9DE061B7A4653|
+
+Lead PE-section mapping gives raw offsets00039160/0003A540/001A0210.
+The call at0043A553 is E808ECFFFF, resolving to00439160; the initial
+GetScreenshotSurface vcall is offset3C (GenerateSurfaceFromFrontBuffer).
+The D3D function's005A0256 call is FF9384000000, the named
+IDirect3DDevice9 GetFrontBufferData vtable slot. The named body and bytes
+agree on allocating a front-buffer-sized surface, then calling that capture.
+GetScreenshotSurface crops to the client rectangle in windowed mode.
+This is evidence for capturing completed front-buffer contents, NOT a claim
+that Vulkan's acquired-image retained-copy technique is literal D3D retail.
+The current PNG/location conventions and typed RHI lifetime remain modern
+adaptations; no screenshot numbering, format or orientation change is proposed.