Fix docker file

Dockerfile

@@ -1,40 +1,104 @@
+# Multi-stage Dockerfile.
+#
+# Why two stages
+# ──────────────
+# `canvas` is a native-binding npm package. It needs Cairo/Pango/etc.
+# at runtime, and python3+make+g++ at install-time to compile its
+# native bindings (no prebuilt binary covers the alpine musl+napi+linux
+# combination at this canvas version; prebuild-install falls back to
+# node-gyp, which needs the compile toolchain).
+#
+# The naive single-stage approach would either:
+#   (a) keep python3+make+g++ in the final image — inflates the image
+#       by ~200MB of build tools nothing uses at runtime, or
+#   (b) try to install --omit=dev in a runtime-only image — fails
+#       because canvas tries to compile and has no python (this was
+#       the bug fixed in this revision).
+#
+# Two-stage solves both: install + compile + prune dev deps in the
+# builder (which has the toolchain), then COPY the resulting
+# node_modules into a slim runtime that only carries the C runtime
+# libs canvas needs at execution time.
+
+# ─────────────────────────────────────────────────────────────────
+# Stage 1: builder
+# Installs all deps (including dev), compiles native bindings,
+# builds the Vite bundle, then prunes dev deps so node_modules is
+# production-ready before we copy it.
+# ─────────────────────────────────────────────────────────────────
 FROM node:20-alpine AS builder
 
-RUN apk add --no-cache cairo-dev pango-dev libjpeg-turbo-dev giflib-dev librsvg-dev pixman-dev python3 make g++
+# Native-binding build prerequisites:
+#   • python3 / make / g++ — node-gyp toolchain for compiling canvas
+#   • cairo-dev / pango-dev / etc. — headers canvas links against
+# These stay in the builder stage only; the runtime stage carries
+# the matching runtime libraries (no -dev suffix) without the
+# toolchain.
+RUN apk add --no-cache \
+    cairo-dev pango-dev libjpeg-turbo-dev giflib-dev librsvg-dev pixman-dev \
+    python3 make g++
 
 WORKDIR /app
+
+# Copy package manifests first so docker can cache the npm install
+# layer when only application source changes.
 COPY package*.json ./
 RUN npm install
+
 COPY . .
 
-# Pull Google Fonts into ./fonts/ so they end up in the runtime image. If the
-# build host has no network this step will produce missing-variant warnings;
-# the build still succeeds and the server falls back to system fonts.
+# Pull Google Fonts into ./fonts/ so they end up in the runtime image.
+# If the build host has no network this step will produce missing-variant
+# warnings; the build still succeeds and the server falls back to system
+# fonts.
 RUN npm run fetch-fonts || echo "Font fetch had warnings; continuing with whatever was downloaded."
 
 RUN npm run build
 
+# Drop dev dependencies (vitest, playwright, eslint, etc.) so the
+# node_modules we copy to runtime is production-only. This is the
+# step that was missing before — without it, the runtime stage had
+# to re-run `npm install` from scratch, which would re-trigger
+# canvas's native compile in an image that doesn't have the
+# toolchain. By pruning here, the runtime stage just copies the
+# already-compiled directory.
+RUN npm prune --production
+
+# ─────────────────────────────────────────────────────────────────
+# Stage 2: runtime
+# Carries only the runtime C libraries canvas links against plus
+# the fonts the export pipeline needs. node_modules is copied
+# whole from the builder; no `npm install` happens here.
+# ─────────────────────────────────────────────────────────────────
 FROM node:20-alpine
 
 # Cairo + Pango are required by node-canvas at runtime.
-# The font packages cover the proprietary template families (Impact, Times,
-# Courier, Arial) via free equivalents that fontconfig will alias, plus emoji
-# rendering for sticker exports.
+# The font packages cover the proprietary template families (Impact,
+# Times, Courier, Arial) via free equivalents that fontconfig will
+# alias, plus emoji rendering for sticker exports.
 RUN apk add --no-cache \
     cairo pango libjpeg-turbo giflib librsvg pixman \
     ttf-liberation ttf-dejavu font-noto font-noto-emoji \
     fontconfig
 
 WORKDIR /app
-COPY package*.json ./
-RUN npm install --omit=dev
 
+# Bring the production node_modules over from the builder rather
+# than installing fresh. This carries the already-compiled canvas
+# .node binary without needing python/make/g++ in this stage.
+COPY --from=builder /app/node_modules ./node_modules
+COPY --from=builder /app/package*.json ./
+
+# Application files. server.js is the entry point; dist/ is the
+# Vite build output served as static; fonts/ is the result of
+# fetch-fonts above.
 COPY server.js ./
 COPY --from=builder /app/dist ./dist
 COPY --from=builder /app/fonts ./fonts
 RUN mkdir -p /app/uploads /app/exports
 
-# Refresh fontconfig's cache so the newly-copied custom fonts are discoverable.
+# Refresh fontconfig's cache so the newly-copied custom fonts are
+# discoverable.
 RUN fc-cache -f /app/fonts || true
 
 HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \