build: fix silent vcvarsall.bat failure and add Claude Code build skills

Invoking vcvarsall.bat via Push-Location + relative name silently no-ops
when the detected Visual Studio install is missing the C++ build tools
workload: cmd.exe prints "'vcvarsall.bat' is not recognized" to stderr,
the inner `set` still runs and dumps the existing environment, the
ForEach loop re-sets the same env (no-op), and the script proceeds
without VC env loaded. meson then fails with a cryptic "cl.exe not
found" later in the build, hiding the real cause. The same bug exists
in bridge/build_common.ps1::SetupVS.

Resolve vcvarsall.bat by full path with an explicit Test-Path guard,
and verify LIBPATH is set after the env-load loop. vcvarsall's exit
code isn't propagated through the cmd-piped-into-ForEach construct, so
the LIBPATH check is what catches the silent-failure case.

Also add two Claude Code skill files under .claude/skills/ that document
the canonical invocation of build_dxvk.ps1 (runtime) and
bridge\build_bridge_release.bat (bridge) for LLM-driven contributor
workflows. These do not change the build itself -- they only describe
the existing entry points and what success and failure look like.

Author: Kim2091

.claude/skills/bridge-build/SKILL.md

@@ -0,0 +1,71 @@
+---
+name: bridge-build
+description: Build the Remix Bridge (32-bit client d3d9 + 64-bit server NvRemixBridge) via bridge\build_bridge_release.bat (or its debug / debugoptimized siblings). Use when the user asks to build, compile, compile-check, or smoke-test the bridge specifically — the bridge is a separate component from the runtime. Reports exit code + verifies artifacts. Do NOT invoke for runtime-side edits (src/dxvk/).
+---
+
+# bridge-build
+
+The bridge is the IPC layer that lets a 32-bit game talk to the 64-bit
+Remix runtime. Client (32-bit `d3d9.dll`) and server (64-bit
+`NvRemixBridge.exe`) build into separate meson directories (one per
+arch). The `bridge\build_bridge_*.bat` wrappers internally call
+[`build_bridge.ps1`](../../../bridge/build_bridge.ps1) twice — once per arch.
+
+## When to invoke
+
+- User asks to build, compile, compile-check, or smoke-test the bridge
+- After a code change under `bridge/src/`
+- After a change to [`public/include/remix/remix_c.h`](../../../public/include/remix/remix_c.h)
+  (the bridge consumes that header)
+- Before pushing bridge changes
+
+## When NOT to invoke
+
+- Edits only under `src/dxvk/` — invoke [`rtx-build`](../rtx-build/SKILL.md) instead
+- Doc-only changes
+- When the user asks for the main runtime build
+
+## Steps
+
+1. From the project root, kick off the bridge build with
+   `run_in_background: true` (expected duration: ~30s incremental,
+   2-4 min cold full for both arches):
+
+   ```powershell
+   .\bridge\build_bridge_release.bat
+   ```
+
+   For other flavors: `.\bridge\build_bridge_debug.bat`,
+   `.\bridge\build_bridge_debugoptimized.bat`, or
+   `.\bridge\build_bridge_all.bat` for all three.
+
+2. Wait for the task-completion notification — do not poll.
+
+3. Report back:
+   - **Green (exit 0):** verify all three artifacts exist, then quote
+     their paths and mtimes:
+     - `bridge\_compRelease_x64\src\server\NvRemixBridge.exe` (x64 server)
+     - `bridge\_compRelease_x86\src\client\d3d9.dll` (x86 client)
+     - `bridge\_compRelease_x86\src\launcher\NvRemixLauncher32.exe` (x86 launcher)
+   - **Mixed-mtime warning:** if x64 server and x86 client mtimes are
+     from very different times, flag this — IPC ABI risk if shared
+     command opcodes / structs under `bridge/src/util/` shifted between
+     builds.
+   - **Red (non-zero exit):** scan the captured output for
+     `error C[0-9]`, `FAILED:`, or `ninja: build stopped`. Quote the
+     first ~10 error lines verbatim.
+
+## Flavors
+
+| Flavor | x64 dir | x86 dir |
+|---|---|---|
+| release (default) | `_compRelease_x64` | `_compRelease_x86` |
+| debug | `_compDebug_x64` | `_compDebug_x86` |
+| debugoptimized | `_compDebugOptimized_x64` | `_compDebugOptimized_x86` |
+
+## Notes
+
+- Requires the MSVC v142 toolchain (VS2019, or VS2022 with the v142
+  Individual Component installed).
+- The bridge can run standalone (without the main `dxvk-remix` runtime)
+  — useful for IPC smoke tests, but no pathtracing.

.claude/skills/rtx-build/SKILL.md

@@ -0,0 +1,62 @@
+---
+name: rtx-build
+description: Build the dxvk-remix runtime (64-bit d3d9.dll) via build_dxvk.ps1. Use when the user asks to build, compile, compile-check, verify, or smoke-test the runtime. Runs in the background, reports exit code + verifies artifacts. Do NOT invoke for doc-only edits.
+---
+
+# rtx-build
+
+Wraps [`build_dxvk.ps1`](../../../build_dxvk.ps1), which dot-sources
+`build_common.ps1` for Visual Studio toolchain discovery and then calls
+`PerformBuild`. Runs in the background so the user isn't blocked, then
+reports the exit code and verifies the expected build artifact exists.
+
+## When to invoke
+
+- User asks to build, compile, compile-check, verify, or smoke-test the runtime
+- After a code change that touches `src/dxvk/` or other runtime sources
+- Before pushing runtime-side code changes
+
+## When NOT to invoke
+
+- Doc-only changes (`.md`, `documentation/`)
+- Settings / skill / config edits
+- Bridge-only changes — invoke [`bridge-build`](../bridge-build/SKILL.md) instead
+- Before the user has finished their code edits — building against a
+  work-in-progress tree wastes time
+
+## Steps
+
+1. From the project root, kick off the build with `run_in_background: true`
+   (expected duration: ~30s incremental, 10-15 min cold full):
+
+   ```powershell
+   .\build_dxvk.ps1 -Backend ninja -BuildFlavour release -BuildSubDir _Comp64Release -EnableTracy false
+   ```
+
+   For other flavors, see the table below.
+
+2. Wait for the task-completion notification — do not poll.
+
+3. Report back:
+   - **Green (exit 0):** verify `_Comp64Release/src/d3d9/d3d9.dll` and
+     `_output/d3d9.dll` exist, then quote their paths and mtimes.
+   - **Red (non-zero exit):** scan the captured output for
+     `error C[0-9]`, `fatal error`, `FAILED:`, or `ninja: build stopped`.
+     Quote the first ~10 error lines so the user sees the real cause
+     before any fix attempt.
+
+## Flavors
+
+| Flavor | `-BuildFlavour` | `-BuildSubDir` |
+|---|---|---|
+| release (default) | `release` | `_Comp64Release` |
+| debug | `debug` | `_Comp64Debug` |
+| debugoptimized | `debugoptimized` | `_Comp64DebugOptimized` |
+
+## Notes
+
+- `LNK4098: defaultlib 'LIBCMT' conflicts` is a known warning, not a failure.
+- The build produces `d3d9.dll` in `_Comp64Release/src/d3d9/` and installs
+  it to `_output/`.
+- Requires the MSVC v142 toolchain (VS2019, or VS2022 with the v142
+  Individual Component installed).

bridge/build_common.ps1

@@ -57,16 +57,26 @@ function SetupVS {
 	#If (Test-Path env:LIBPATH) {
 	#  Write-Host "Visual Studio Command Prompt variables already set." -ForegroundColor Yellow
 	#} Else {
-	  # Load VC vars
-	  Push-Location "${vsPath}\VC\Auxiliary\Build"
+	  # Invoke vcvarsall.bat by full path so a missing C++ workload fails
+	  # loudly here rather than letting meson surface a cryptic "cl.exe not
+	  # found" downstream.
+	  $vcvarsall = Join-Path "${vsPath}\VC\Auxiliary\Build" "vcvarsall.bat"
+	  If (-not (Test-Path $vcvarsall)) {
+	    Write-Error "vcvarsall.bat not found at '$vcvarsall'. The detected Visual Studio installation may be missing the C++ build tools workload." -ErrorAction Stop
+	  }
 
-	  cmd /c "vcvarsall.bat $Platform &set" |
+	  cmd /c "call `"$vcvarsall`" $Platform & set" |
 		ForEach-Object {
 		  If ($_ -match "=") {
 			$v = $_.split("="); Set-Item -Force -Path "ENV:\$($v[0])" -Value "$($v[1])"
 		  }
 		}
-	  Pop-Location
+
+	  # vcvarsall.bat doesn't propagate its own exit code through the pipe.
+	  # Use LIBPATH presence as the signal that the toolchain env loaded.
+	  If (-not (Test-Path env:LIBPATH)) {
+	    Write-Error "vcvarsall.bat ran but did not set LIBPATH; cannot continue." -ErrorAction Stop
+	  }
 	  Write-Host "Visual Studio Command Prompt variables set." -ForegroundColor Yellow
 	#}
 }

build_common.ps1

@@ -52,9 +52,15 @@ Write-Host "Using Visual Studio installation at: ${vsPath}" -ForegroundColor Yel
 If (Test-Path env:LIBPATH) {
   Write-Host "Visual Studio Command Prompt variables already set." -ForegroundColor Yellow
 } Else {
-  # Load VC vars
-  Push-Location "${vsPath}\VC\Auxiliary\Build"
-  cmd /c "vcvarsall.bat x64&set" |
+  # Invoke vcvarsall.bat by full path so a missing C++ workload fails
+  # loudly here rather than letting meson surface a cryptic "cl.exe not
+  # found" downstream.
+  $vcvarsall = Join-Path "${vsPath}\VC\Auxiliary\Build" "vcvarsall.bat"
+  If (-not (Test-Path $vcvarsall)) {
+    Write-Error "vcvarsall.bat not found at '$vcvarsall'. The detected Visual Studio installation may be missing the C++ build tools workload." -ErrorAction Stop
+  }
+
+  cmd /c "call `"$vcvarsall`" x64 & set" |
 	ForEach-Object {
 	  # Due to some odd behavior with how powershell core (pwsh) (powershell 5.X not tested) interprets a specific
 	  # predefined gitlab CI variable (in this case CI_MERGE_REQUEST_DESCRIPTION) with a value that includes ===  
@@ -65,7 +71,12 @@ If (Test-Path env:LIBPATH) {
 		  }
 	  }
 	}
-  Pop-Location
+
+  # vcvarsall.bat doesn't propagate its own exit code through the pipe.
+  # Use LIBPATH presence as the signal that the toolchain env loaded.
+  If (-not (Test-Path env:LIBPATH)) {
+    Write-Error "vcvarsall.bat ran but did not set LIBPATH; cannot continue." -ErrorAction Stop
+  }
   Write-Host "Visual Studio Command Prompt variables set." -ForegroundColor Yellow
 }