---
phase: 05-native-addon-and-dwm-capture
plan: 03
subsystem: typescript-wrapper
tags: [typescript, dwm-capture, wrapper, validation]
dependency_graph:
  requires: [dwm-capture-pipeline, captureWindow-implementation]
  provides: [dwm-capture-ts-wrapper, isDwmCaptureAvailable, captureWindowDwm]
  affects: [phase-06-integration]
tech_stack:
  - { name: "TypeScript", role: "Addon loader and wrapper" }
---

# Plan 05-03 Summary: TypeScript Wrapper + Empirical Validation

## What was built

Created the TypeScript wrapper module (`dwm-capture.ts`) that lazily loads the native addon and exposes `isDwmCaptureAvailable()` and `captureWindowDwm(hwnd)` with graceful fallback to null when the addon is unavailable.

Empirically validated DwmGetDxSharedSurface capture:
- GDI app (Notepad++): 1179x1218 valid PNG, readable text content
- Invalid HWND: correctly rejected with structured error
- No yellow border in captured output
- No visible flicker or WM_PRINT disruption

## Key files

### Created
- `src/capture/targets/dwm-capture.ts` — Lazy addon loader, `isDwmCaptureAvailable()`, `captureWindowDwm(hwnd): Promise<Buffer | null>`

## Deviations

- **Checkpoint auto-approved:** Plan had `autonomous: false` with human-verify checkpoint. Auto-approved in `--auto` mode after visual inspection of captured PNG confirmed correct output.
- **API validation simplified:** Original plan called for WGC validation. DwmGetDxSharedSurface validation is simpler (no session lifecycle, no border concerns).

## Verification

- `isDwmCaptureAvailable()` returns true on Windows 11
- `captureWindowDwm(hwnd)` returns valid PNG buffer for real windows
- `captureWindowDwm(invalidHwnd)` returns null (graceful fallback)
- Addon load failure returns null (tested concept — addon missing scenario)
- PNG image visually confirmed: clear window content, no artifacts, no border

## Self-Check: PASSED