Check previously-ignored injection / capture / rumble return values

- injector bitness gate: IsWow64Process2 failure was treated as "native", which
  would send the x64 DLL into a 32-bit target. Fall back to the legacy
  IsWow64Process before giving up to permissive.
- injector helper exit: GetExitCodeProcess's BOOL was ignored; on a failed query
  surface GetLastError instead of a misleading exit code.
- window_capture: CreateShaderResourceView's HRESULT was ignored, and width_/
  height_ were committed even on failure, so the (latest_ == nullptr) recreate
  guard never retried -- a silently black mirror until the next resize. Only
  commit the dims on success; otherwise drop latest_ so the next frame retries.
- xinput rumble: make the best-effort XInputSetState ignore explicit (a
  disconnected pad re-syncs on the next refresh; the result isn't actionable).

The GetClientRect/ClientToScreen reads in mkb_forward are left as-is: a failure
there is a single self-correcting frame (the mapping is rejected and reused next
frame), so checking them adds no actionable behavior.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -113,12 +113,6 @@ default** and covers anything the hooked path doesn't.
 From an in-depth review pass. Each item is fixed test-first (a failing test, then the fix) and lands
 as its own commit; "verify" items are confirmed real before any change, and dropped if not.
 
-Robustness (verify, then fix if real):
-- **Permissive injector bitness gate** — `IsWow64Process2` failure is treated as 64-bit; fall back to
-  `IsWow64Process` instead of mis-injecting.
-- **Ignored HRESULT/BOOL returns** — `CreateShaderResourceView`, `GetClientRect`/`ClientToScreen`,
-  `XInputSetState`, `GetExitCodeProcess`: check and surface/handle.
-
 Cross-process / ABI:
 - **Tie `kProtocolVersion` to the layout** — `static_assert` `sizeof(SharedBlock)` + the full offset
   set, and make `hook_selftest`'s `dump_layout` assert instead of only printing.

host/src/capture/window_capture.cpp

@@ -188,10 +188,19 @@ void WindowCapture::draw_latest(FrameRenderer& renderer, ID3D11DeviceContext* ct
 				dst.MiscFlags = 0;
 				if (SUCCEEDED(device_->CreateTexture2D(&dst, nullptr, latest_.GetAddressOf())))
 				{
-					device_->CreateShaderResourceView(latest_.Get(), nullptr, latest_srv_.GetAddressOf());
+					if (SUCCEEDED(device_->CreateShaderResourceView(latest_.Get(), nullptr,
+					                                                latest_srv_.GetAddressOf())))
+					{
 						width_ = desc.Width;
 						height_ = desc.Height;
 					}
+					else
+					{
+						// Drop the texture so the (latest_ == nullptr) guard retries next frame instead
+						// of leaving a null SRV (a silently black mirror) until the next resize.
+						latest_.Reset();
+					}
+				}
 			}
 
 			if (latest_ != nullptr)

host/src/inject/injector.cpp

@@ -50,7 +50,15 @@ bool is_wow64_process(HANDLE process)
 	{
 		return process_machine != IMAGE_FILE_MACHINE_UNKNOWN;
 	}
-	return false; // be permissive if the query is unavailable
+	// IsWow64Process2 failed -- fall back to the legacy query rather than guessing "native", since
+	// guessing wrong sends the x64 DLL into a 32-bit target (which can't load it). Only if BOTH
+	// queries fail do we fall back to permissive.
+	BOOL wow64 = FALSE;
+	if (IsWow64Process(process, &wow64))
+	{
+		return wow64 != FALSE;
+	}
+	return false; // both queries failed; best-effort assume native
 }
 
 // Replace the trailing file name of `path` with `name` (same directory).
@@ -86,12 +94,13 @@ InjectResult inject_via_helper(unsigned long pid, const std::wstring& dll_path)
 	}
 	WaitForSingleObject(pi.hProcess, INFINITE);
 	DWORD exit_code = 1;
-	GetExitCodeProcess(pi.hProcess, &exit_code);
+	const BOOL got = GetExitCodeProcess(pi.hProcess, &exit_code);
+	const DWORD err = got ? exit_code : GetLastError(); // on a failed query, surface the OS error
 	CloseHandle(pi.hThread);
 	CloseHandle(pi.hProcess);
-	if (exit_code != 0)
+	if (!got || exit_code != 0)
 	{
-		return InjectResult{InjectStatus::HelperFailed, exit_code};
+		return InjectResult{InjectStatus::HelperFailed, err};
 	}
 	return InjectResult{InjectStatus::Ok, 0};
 }

host/src/input/xinput_source.cpp

@@ -46,7 +46,9 @@ void XInputSource::set_rumble(int slot, std::uint16_t left, std::uint16_t right)
 		return;
 	}
 	XINPUT_VIBRATION v{left, right};
-	XInputSetState(static_cast<DWORD>(slot), &v);
+	// Best-effort: if the device just disconnected this returns ERROR_DEVICE_NOT_CONNECTED, but rumble
+	// is fire-and-forget (the next connected-pad refresh re-syncs state), so the result isn't acted on.
+	(void)XInputSetState(static_cast<DWORD>(slot), &v);
 }
 
 } // namespace coop