Phase 5e: the LaTeX emitter — the guide compiles into a real book

.github/workflows/book.yml

@@ -0,0 +1,35 @@
+# Compiles the book from the same content the app renders. The PDF lands as
+# a workflow artifact on every push to main that touches content or the
+# emitter — the printed book can never drift from the live guide.
+name: book
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'src/content/**'
+      - 'scripts/emit-latex.ts'
+      - '.github/workflows/book.yml'
+  workflow_dispatch:
+
+jobs:
+  pdf:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: npm
+      - run: npm ci
+      - name: Emit LaTeX
+        run: npm run book:tex
+      - uses: wtfjoke/setup-tectonic@v3
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Compile PDF
+        run: tectonic book/gradient-lab.tex
+      - uses: actions/upload-artifact@v4
+        with:
+          name: gradient-lab-pdf
+          path: book/gradient-lab.pdf

.gitignore

@@ -24,3 +24,4 @@ dist-ssr
 *.sln
 *.sw?
 .claude/launch.json
+book/

package.json

@@ -8,7 +8,9 @@
     "build": "vite build",
     "preview": "vite preview",
     "check": "svelte-check --tsconfig ./tsconfig.app.json && tsc -p tsconfig.node.json",
-    "test": "vitest run"
+    "test": "vitest run",
+    "book:tex": "vite-node scripts/emit-latex.ts",
+    "book": "npm run book:tex && tectonic book/gradient-lab.tex"
   },
   "devDependencies": {
     "@sveltejs/vite-plugin-svelte": "^7.0.0",
@@ -19,6 +21,7 @@
     "svelte-check": "^4.4.6",
     "typescript": "^6.0.3",
     "vite": "^8.0.10",
+    "vite-node": "^6.0.0",
     "vite-plugin-pwa": "^1.3.0",
     "vitest": "^4.1.8"
   },