build: run the browser e2e suites in CI (closes #259)

tests/e2e/Dockerfile

@@ -0,0 +1,34 @@
+# Chrome end-to-end image: the pinned Playwright image with this repo and a
+# freshly built extension inside it, built by script/test-e2e. The suite is
+# still started with `docker run`, so every runtime flag the harness needs
+# (--ipc=host in particular) applies as before.
+#
+# The repo is baked in rather than bind-mounted because a bind mount does
+# not resolve under Gitea Actions: the runner runs the job in a container
+# against the HOST's docker socket, so the source side of a -v is resolved
+# by the host daemon while the job's checkout lives on a docker volume that
+# is not a host path -- the mount silently succeeds and /work is empty. A
+# build context is streamed to the daemon and so works from anywhere.
+# Building the extension here too means the machine starting a run needs
+# docker and nothing else.
+
+# mcr.microsoft.com/playwright:v1.56.0-noble, 2026-08-09
+#
+# The playwright-core devDependency is pinned to the matching Playwright
+# version (1.56.0) and the two must be bumped together: the browsers ship
+# inside this image, and playwright-core looks for the exact browser
+# revision its own version expects. A mismatch fails at launch.
+FROM mcr.microsoft.com/playwright@sha256:35246d87a7c88ea9b771c65d33171b2611b02a8253b4b12ce6f94376c55f99f2
+
+WORKDIR /work
+
+# Same layering as the root Dockerfile: script/bootstrap installs the
+# prerequisites and the dependencies, and the manifests are copied first so
+# that layer is cached until they change.
+COPY script/ script/
+COPY package.json yarn.lock ./
+RUN script/bootstrap
+
+COPY . .
+
+RUN make build

tests/e2e/firefox/Dockerfile

@@ -1,10 +1,24 @@
 # Firefox end-to-end image: stock Firefox plus geckodriver on a node base,
-# built by script/test-e2e-firefox. The repo is bind-mounted at /work; the
-# harness itself has no dependencies, so nothing is installed for it.
+# with this repo and a freshly built extension inside it, built by
+# script/test-e2e-firefox. The harness itself has no dependencies, so
+# nothing is installed for it.
 #
-# All three external artifacts are pinned by digest. The Firefox version in
-# particular must not float: -remote-allow-system-access is mandatory on 153
-# and was not on 142, so the flag the harness passes is version-coupled.
+# The build context is the repo root. The repo is baked in rather than
+# bind-mounted because a bind mount does not resolve under Gitea Actions:
+# the runner runs the job in a container against the HOST's docker socket,
+# so the source side of a -v is resolved by the host daemon while the job's
+# checkout lives on a docker volume that is not a host path -- the mount
+# silently succeeds and /work is empty. Baking the build in is also the
+# only way this suite can have both a built extension and the
+# `--network none` it runs under, since a container with no network cannot
+# install anything.
+#
+# All three external artifacts are pinned by digest, and are fetched in
+# layers above the repo copy, so editing the harness or any source file
+# re-runs only the two cheap layers at the bottom. The Firefox version in
+# particular must not float: -remote-allow-system-access is mandatory on
+# 153 and was not on 142, so the flag the harness passes is
+# version-coupled.
 
 # node:22-bookworm-slim, 2026-08-12
 FROM node@sha256:d649c27dae7ba0137b3cef5dd75baa422c08dc3d9e3fc0c23dfb172dc3cc6436
@@ -48,4 +62,16 @@ ENV FIREFOX_BIN=/opt/firefox/firefox
 ENV GECKODRIVER=/usr/local/bin/geckodriver
 
 WORKDIR /work
+
+# Same layering as the root Dockerfile: script/bootstrap installs the
+# prerequisites and the dependencies, and the manifests are copied first so
+# that layer is cached until they change.
+COPY script/ script/
+COPY package.json yarn.lock ./
+RUN script/bootstrap
+
+COPY . .
+
+RUN make build
+
 CMD ["node", "tests/e2e/firefox/run.js", "dist/firefox"]