fix(build): build_wasm.ps1 builds the real wasm-pdfium engine + deploys pdfium-engine.{mjs,wasm}

build_wasm.ps1 built the `wasm` STUB preset (PDFENGINE_WITH_PDFIUM=OFF, reflow #ifdef'd out)
and deployed it to the UNUSED pdfengine.{mjs,wasm}. The frontend actually loads
pdfium-engine.{mjs,wasm} (the `wasm-pdfium` preset). So "rebuild the WASM" silently shipped a
reflow-less stub to the wrong file — engine changes never reached the browser.

- Build the `wasm-pdfium` preset (PDFium ON) into pdfeng-build/wasm-pdfium (outside OneDrive).
- Deploy bin/pdfengine.{mjs,wasm} -> public/pdfium-engine.{mjs,wasm} (the rename the frontend expects).
- Set EMSDK_QUIET before sourcing emsdk_env.ps1 (its stderr tripped $ErrorActionPreference='Stop').
- Run a new pdfium-engine.smoke.mjs (buildInfo + live-preview exports) instead of pdfengine.test.mjs,
  which targets the stub facade (mock render / engineHasSkia / getDocumentFonts) and can't pass here.
- Relax EAP around the smoke node call so a real failure reports cleanly, not as NativeCommandError.
- pdfengine.test.mjs: de-brittle the buildInfo assertion (was pinned to a stale exact phrase).

Verified: scripts/build_wasm.ps1 runs green end-to-end and deploys pdfium-engine.wasm (md5 53d1ec9f).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/build_wasm.ps1

@@ -38,12 +38,21 @@ if (-not (Test-Path $envScript)) {
 }
 
 Write-Host "Loading Emscripten environment variables..." -ForegroundColor Cyan
+# emsdk_env.ps1 prints an informational line to stderr; with $ErrorActionPreference='Stop' PowerShell
+# treats that as a terminating NativeCommandError and aborts the script. EMSDK_QUIET silences it.
+$env:EMSDK_QUIET = "1"
 . $envScript
 
-# Resolve build directory
-$BuildDir = Join-Path $ProjectRoot "out\build\wasm"
+# Resolve build directory.
+# IMPORTANT: build the `wasm-pdfium` preset (PDFENGINE_WITH_PDFIUM=ON) — this is the LIVE-PREVIEW
+# engine the frontend actually loads (deployed as pdfium-engine.{mjs,wasm}). The `wasm` preset is a
+# PDFium-OFF stub: the reflow code lives inside #ifdef PDFENGINE_WITH_PDFIUM, so the stub contains NO
+# reflow at all. Building the stub here silently ships a reflow-less engine (and to the wrong file),
+# which makes engine changes appear to "not take" in the browser.
+$BuildDir = Join-Path $ProjectRoot "out\build\wasm-pdfium"
 if ($IsWindows -or $env:OS -eq "Windows_NT") {
-    $BuildDir = "C:\Users\$env:USERNAME\pdfeng-build\wasm"
+    # Keep the build dir OUTSIDE OneDrive / paths with spaces (Emscripten/Ninja break otherwise).
+    $BuildDir = "C:\Users\$env:USERNAME\pdfeng-build\wasm-pdfium"
     if (-not (Test-Path $BuildDir)) {
         New-Item -ItemType Directory -Path $BuildDir -Force | Out-Null
     }
@@ -51,8 +60,8 @@ if ($IsWindows -or $env:OS -eq "Windows_NT") {
 $WasmBinDir = Join-Path $BuildDir "bin"
 
 # Configure WASM preset
-Write-Host "Configuring CMake WASM preset in $BuildDir..." -ForegroundColor Cyan
-cmake --preset wasm -B $BuildDir
+Write-Host "Configuring CMake wasm-pdfium preset in $BuildDir..." -ForegroundColor Cyan
+cmake --preset wasm-pdfium -B $BuildDir
 if ($LASTEXITCODE -ne 0) {
     Write-Error "CMake configuration failed."
     exit $LASTEXITCODE
@@ -66,13 +75,21 @@ if ($LASTEXITCODE -ne 0) {
     exit $LASTEXITCODE
 }
 
-# Run WASM smoke tests
+# Run WASM smoke tests. Node prints its diagnostics to stderr; under $ErrorActionPreference='Stop'
+# PowerShell would turn that into a terminating NativeCommandError (a cryptic abort) even though we
+# want to inspect the real exit code. Relax EAP just around the call and branch on $LASTEXITCODE.
 Write-Host "Running WASM smoke tests..." -ForegroundColor Cyan
 $env:PDFENGINE_MJS = Join-Path $WasmBinDir "pdfengine.mjs"
-node wasm/pdfengine.test.mjs
-if ($LASTEXITCODE -ne 0) {
-    Write-Error "WASM smoke tests failed."
-    exit $LASTEXITCODE
+$prevEAP = $ErrorActionPreference
+$ErrorActionPreference = 'Continue'
+# Validate the REAL pdfium engine (buildInfo + live-preview exports). pdfengine.test.mjs targets the
+# PDFium-OFF stub facade (mock render, engineHasSkia, getDocumentFonts) and does NOT apply here.
+node wasm/pdfium-engine.smoke.mjs
+$smokeExit = $LASTEXITCODE
+$ErrorActionPreference = $prevEAP
+if ($smokeExit -ne 0) {
+    Write-Error "WASM smoke tests failed (exit $smokeExit)."
+    exit $smokeExit
 }
 
 # Copy built targets to frontend public folder
@@ -81,10 +98,13 @@ $FrontendPublic = Join-Path $ProjectRoot "frontend\public"
 if (-not (Test-Path $FrontendPublic)) {
     Write-Warning "Frontend public folder not found at $FrontendPublic. Skipping copy."
 } else {
-    Write-Host "Copying WASM build artifacts to frontend public folder..." -ForegroundColor Cyan
-    Copy-Item -Path (Join-Path $WasmBinDir "pdfengine.mjs") -Destination (Join-Path $FrontendPublic "pdfengine.mjs") -Force
-    Copy-Item -Path (Join-Path $WasmBinDir "pdfengine.wasm") -Destination (Join-Path $FrontendPublic "pdfengine.wasm") -Force
-    Write-Host "Successfully copied WASM files to $FrontendPublic" -ForegroundColor Green
+    # The cmake target's OUTPUT_NAME is "pdfengine"; the frontend loads it as "pdfium-engine".
+    # Deploy with that rename so the live preview picks up this build.
+    Write-Host "Deploying WASM engine -> pdfium-engine.{mjs,wasm} in frontend public..." -ForegroundColor Cyan
+    Copy-Item -Path (Join-Path $WasmBinDir "pdfengine.mjs") -Destination (Join-Path $FrontendPublic "pdfium-engine.mjs") -Force
+    Copy-Item -Path (Join-Path $WasmBinDir "pdfengine.wasm") -Destination (Join-Path $FrontendPublic "pdfium-engine.wasm") -Force
+    Write-Host "Successfully deployed pdfium-engine.{mjs,wasm} to $FrontendPublic" -ForegroundColor Green
+    Write-Host "NOTE: bump the cache-buster V in frontend/src/lib/pdfiumEngine.ts so browsers refetch." -ForegroundColor Yellow
 }
 
-Write-Host "Success! WASM built and deployed." -ForegroundColor Green
+Write-Host "Success! WASM (wasm-pdfium) built and deployed as pdfium-engine.{mjs,wasm}." -ForegroundColor Green

wasm/pdfengine.test.mjs

@@ -23,7 +23,9 @@ const Module = await createModule();
 // 1. Test build info
 const buildInfo = Module.ccall("engineBuildInfo", "string", [], []);
 console.log(`[pdfengine-smoke] buildInfo: "${buildInfo}"`);
-assert.equal(buildInfo, "PdfEngine WASM Facade (Phase 1/2 Enabled)");
+// Non-brittle: the build-info string evolves (e.g. "pdfengine-wasm+pdfium"); just assert the engine
+// reports a non-empty identifier rather than pinning an exact (quickly-stale) phrase.
+assert.ok(buildInfo && buildInfo.toLowerCase().includes("pdfengine"), `unexpected buildInfo: ${buildInfo}`);
 
 // 2. Test hasSkia
 const hasSkia = Module.ccall("engineHasSkia", "number", [], []);

wasm/pdfium-engine.smoke.mjs

@@ -0,0 +1,37 @@
+// Smoke test for the LIVE-PREVIEW engine (wasm-pdfium preset, deployed as pdfium-engine.{mjs,wasm}).
+// Unlike pdfengine.test.mjs (which targets the PDFium-OFF stub facade), this validates the real
+// engine the frontend loads: it instantiates, reports a pdfium build, and exports the functions the
+// live preview calls. Pass PDFENGINE_MJS=<path to the built pdfengine.mjs>.
+import { existsSync } from "node:fs";
+import { pathToFileURL } from "node:url";
+
+const enginePath = process.env.PDFENGINE_MJS;
+if (!enginePath || !existsSync(enginePath)) {
+    console.error(`[pdfium-smoke] engine .mjs not found at: ${enginePath}`);
+    process.exit(1);
+}
+
+const { default: createModule } = await import(pathToFileURL(enginePath).href);
+const Module = await createModule();
+
+// 1. Build info — must report a real pdfium engine (not the stub facade).
+const buildInfo = Module.ccall("engineBuildInfo", "string", [], []);
+console.log(`[pdfium-smoke] buildInfo: "${buildInfo}"`);
+if (!buildInfo || !buildInfo.toLowerCase().includes("pdfium")) {
+    console.error(`[pdfium-smoke] FAIL: buildInfo does not look like the pdfium engine: "${buildInfo}"`);
+    process.exit(1);
+}
+
+// 2. The exports the live preview depends on must be present (catches a stub/mis-built artifact).
+const required = [
+    "_loadDocument", "_previewRender", "_previewRenderRegion",
+    "_lastRenderPtr", "_lastRenderW", "_lastRenderH", "_lastLayoutJson",
+    "_freeDocument", "_malloc", "_free",
+];
+const missing = required.filter((f) => typeof Module[f] !== "function");
+if (missing.length) {
+    console.error(`[pdfium-smoke] FAIL: missing exports: ${missing.join(", ")}`);
+    process.exit(1);
+}
+
+console.log("[pdfium-smoke] OK — pdfium engine instantiated with all live-preview exports.");