build: unify the gate so root make check covers the backend (closes #16)

Root `make check` only ever ran the frontend, so the "main is always
green" policy was satisfied vacuously: the Go backend could be entirely
broken and the root gate stayed green.

- The backend moves onto scripts-to-rule-them-all. Its test, lint, fmt,
  fmt-check, build, run and clean implementations now live in
  `backend/script/`, and `backend/Makefile` is thin shims. The backend
  is its own project (own module, README, LICENSE, linter config,
  Dockerfile stage), and `Dockerfile.backend` only copies `backend/`
  into its builder, so its scripts have to live under `backend/`.
- The root `script/test`, `script/lint`, `script/fmt` and
  `script/fmt-check` now run the frontend step and then the matching
  `backend/script/*` step, so `script/check` — and therefore the
  pre-commit hook — gates both halves. The frontend-only steps moved
  into `script/frontend-*` so nothing is duplicated.
- `script/bootstrap` now provisions the backend's toolchain as well,
  because widening the gate without widening bootstrap left the
  documented fresh-clone path (`make setup`) installing a pre-commit
  hook that rejected every commit with `golangci-lint: not found`.
  golangci-lint is installed at exactly `2.7.2`, the version
  `Dockerfile.backend` pins, so local findings match CI. Go is reused
  only when the installed version falls inside a window — at least
  `backend/go.mod`'s floor, and no newer in major.minor than the Go the
  pinned linter was built with — otherwise `go1.25.7` is installed. The
  upper bound is load-bearing: golangci-lint links `go/types` from its
  own build toolchain, so the pinned `2.7.2` (built with `go1.25.4`)
  panics with "file requires newer Go version go1.26" against a host Go
  1.26, which would leave `make setup` exiting 0 and every commit
  rejected. Both tools come from a specific release archive whose sha256
  is hardcoded here and verified before anything is unpacked — never an
  install script piped to a shell — and both are symlinked onto `PATH`,
  since nvm-style activation does not reach `make` or the git hook.
- `script/bootstrap` links only into `~/.local/bin` and never into a
  system-wide prefix. `/usr/local/bin` is shared with other users and
  with a package manager — on an Intel Mac it is the Homebrew prefix —
  and pointing an entry there at one user's `$HOME` breaks it for
  everyone else. It also refuses, non-zero, to replace anything it did
  not create: only a symlink already pointing into its own toolchain
  directory is overwritten, so a pre-existing binary is reported rather
  than deleted. `corepack enable` is given `--install-directory` so its
  four shims (`yarn`, `yarnpkg`, `pnpm`, `pnpx`) land inside that same
  toolchain directory instead of beside the corepack binary, and only
  `yarn` is linked onto `PATH`.
- `script/bootstrap` exits non-zero when it cannot guarantee the pinned
  toolchain is the one the gate will run. Reporting success while
  knowing a different linter or a newer Go precedes `~/.local/bin` is
  the same defect this commit exists to remove, so the final step
  re-resolves `go`, `gofmt`, `golangci-lint`, `node` and `yarn` against
  the caller's own `PATH` and fails with what it found and how to fix
  it. The three tools that carry a version constraint are re-checked
  with the same predicates their installs use, not for bare presence:
  `gofmt` is a gate tool — `backend/script/fmt-check` runs it — and its
  output is not guaranteed identical across Go releases, so a `gofmt`
  built by a different Go than the one that compiles the code counts as
  missing. `go` and `gofmt` are relinked on every run in which the
  pinned toolchain is the one in use, rather than only on the run that
  unpacked the archive, so a deleted link is repaired instead of
  falling through to whatever `gofmt` the host happens to have. The
  failure text separates a tool that resolves to the wrong build
  (something shadows `~/.local/bin`) from one that does not resolve at
  all (nothing is shadowing it, it was never installed), and always
  names a real directory rather than interpolating an unset one.
- `script/frontend-check` is the frontend half of the gate, exposed as
  the `frontend-check` target, for the frontend Dockerfile: its build
  stage is a node image with no Go toolchain. The backend half is gated
  by `Dockerfile.backend`, and `script/cibuild` builds both images, so
  the two Dockerfiles together still gate the whole repo. The
  `backend-check` target is the mirror of it. Both targets are named
  after the script they shim, like every other target.
- `script/cibuild` builds both images through one `build_image` helper,
  and the Gitea workflow's only build step is `script/cibuild`; the raw
  `docker build -f Dockerfile.backend .` is gone from the workflow.
  `script/docker` likewise builds and tags both images.
- `backend/Makefile`'s `hooks` target is removed. It wrote the same
  `.git/hooks/pre-commit` as `script/install-precommit`, so the two
  clobbered each other and the developer silently ended up gating on
  only one half of the repo. `script/install-precommit` is now the only
  installer, and the hook it writes runs the repo-wide `script/check`.
- `backend/Makefile`'s `docker` target is removed too: the backend image
  builds from the repo root with a root-level Dockerfile, so it belongs
  to the root `script/docker` and `script/cibuild` rather than to a
  backend script that would have to reach outside `backend/`.
- `backend/script/lint` verifies that `.golangci.yml` still matches its
  pinned sha256 before running the linter. Offline hash comparison, no
  network. The pin is marked provisional in the file: it is the config
  currently on `main`, and the comment names PR #31 and the canonical
  hash that must replace it when #31 lands.
- Every script locates the repo root with the mandated
  `$(cd "$(dirname "$0")/.." && pwd -P)` idiom, `cd`s there, and calls
  siblings as `"$ROOT/script/<name>"`; the `SCRIPT_DIR` variant is gone.

READMEs at the root and in `backend/` document every script, the
backend's Getting Started separates commands run from `backend/` from
those run at the repo root, and `TODO.md` records the change.

.dockerignore

@@ -1,6 +1,5 @@
 node_modules
 dist
-tmp
 .DS_Store
 *.log
 .claude

.gitea/workflows/check.yml

@@ -6,5 +6,6 @@ jobs:
         steps:
             # actions/checkout v4.2.2, 2026-02-22
             - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+            # script/cibuild builds both images; it is the only build
+            # step, so how the repo builds stays defined in script/.
             - run: script/cibuild
-            - run: docker build -f Dockerfile.backend .

.gitignore

@@ -1,5 +1,4 @@
 node_modules/
 dist/
-tmp/
 .DS_Store
 *.log

.prettierignore

@@ -1,6 +1,5 @@
 backend/
 dist/
 node_modules/
-tmp/
 yarn.lock
 .claude/

Dockerfile

@@ -5,10 +5,14 @@ COPY package.json yarn.lock ./
 RUN yarn install --frozen-lockfile
 RUN apk add --no-cache git make
 COPY . .
-# make check runs script/check (test + lint + fmt-check); its test step
-# is the production yarn build, so this both produces dist/ and gates the
-# image on lint/fmt-check/test regressions, not merely a broken build.
-RUN make check
+# make frontend-check runs script/frontend-check (test + lint +
+# fmt-check for the frontend); its test step is the production yarn
+# build, so this both produces dist/ and gates the image on
+# lint/fmt-check/test regressions, not merely a broken build. It is the
+# frontend half of `make check` rather than all of it because this stage
+# is a node image with no Go toolchain; the backend half is gated by
+# Dockerfile.backend, and script/cibuild builds both images.
+RUN make frontend-check
 
 # nginx:stable-alpine as of 2026-02-22
 FROM nginx@sha256:15e96e59aa3b0aada3a121296e3bce117721f42d88f5f64217ef4b18f458c6ab

Makefile

@@ -1,9 +1,10 @@
-.PHONY: bootstrap setup dev test lint fmt fmt-check check \
-	frontend-viewport-test docker hooks
+.PHONY: bootstrap setup dev test lint fmt fmt-check check frontend-check \
+	backend-check docker hooks
 
 # Standard targets are thin shims; the implementations live in script/
 # per the scripts-to-rule-them-all pattern (see the Entrypoints section
-# of README.md).
+# of README.md). test, lint, fmt, fmt-check and check all cover the
+# whole repo: the frontend at the root and the Go backend in backend/.
 
 bootstrap:
 	@script/bootstrap
@@ -29,11 +30,14 @@ fmt-check:
 check:
 	@script/check
 
-# Responsive-layout verification in a containerised browser. Kept out of
-# check: it needs Docker and takes minutes, where make test has to stay
-# under 20 seconds.
-frontend-viewport-test:
-	@script/frontend-viewport-test
+# Half-repo gates. Used by the two Dockerfiles, whose build stages only
+# have the toolchain for their own half; prefer `make check` otherwise.
+# Each is named after the script it shims, like every other target here.
+frontend-check:
+	@script/frontend-check
+
+backend-check:
+	@backend/script/check
 
 docker:
 	@script/docker

README.md

@@ -28,37 +28,64 @@ docker run -p 8080:8080 netwatch
 This repository adheres to the
 [Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
 standard: normalized scripts in `script/` are the entrypoints for the
-development workflow, and the Makefile targets are thin shims that call them. We
-provide:
+development workflow, and the Makefile targets are thin shims that call them.
 
-- `script/bootstrap` — install all dependencies (pinned node via nvm if needed,
-  yarn via corepack, `yarn install --frozen-lockfile`)
+The repo holds two projects: the frontend at the repo root and the Go backend in
+`backend/`, which has its own `script/` directory and its own shim Makefile. The
+root scripts cover both, so `make check` at the root fails if either half is
+broken. We provide:
+
+- `script/bootstrap` — install all dependencies, assuming nothing is present:
+  pinned node via nvm if needed, yarn via corepack,
+  `yarn install --frozen-lockfile`, and the backend's toolchain — Go (an
+  already-installed Go is reused only when its version falls inside the window
+  the pinned golangci-lint can analyse; a newer Go is ignored, not preferred)
+  and golangci-lint at the version `Dockerfile.backend` pins. Everything not
+  installed by the system package manager comes from a hash-verified release
+  archive and is symlinked into `~/.local/bin`, so `make check` works in a plain
+  shell afterwards
 - `script/setup` — make a fresh clone ready for development: bootstrap plus the
   git pre-commit hook
-- `script/projectname` — print the project name (used for the Docker image tag)
-- `script/test` — run the production build as the test (no unit tests yet)
-- `script/lint` — run prettier in check mode
-- `script/fmt` — format all files (writes)
-- `script/fmt-check` — check formatting (read-only)
-- `script/check` — run test, lint, and fmt-check
-- `script/frontend-viewport-test` — responsive-layout verification of the built
-  frontend in a containerised headless Chrome (see
-  [test/viewport/README.md](test/viewport/README.md)). Not part of
-  `script/check`: it needs Docker and takes minutes.
-- `script/docker` — build the Docker image tagged via `script/projectname`
-- `script/cibuild` — CI entrypoint: plain `docker build .`
-- `script/precommit` — run by the git pre-commit hook; runs `script/check`
-- `script/install-precommit` — install the git pre-commit hook
+- `script/projectname` — print the project name (used for the Docker image tags)
+- `script/test` — run the whole repo's tests: `script/frontend-test`, then
+  `backend/script/test`
+- `script/lint` — lint the whole repo: `script/frontend-lint`, then
+  `backend/script/lint`
+- `script/fmt` — format the whole repo (writes): `script/frontend-fmt`, then
+  `backend/script/fmt`
+- `script/fmt-check` — check formatting across the whole repo (read-only)
+- `script/check` — run test, lint, and fmt-check; this is the repo-wide gate
+- `script/frontend-test` — the frontend's test: the production build (no unit
+  tests yet)
+- `script/frontend-lint` — run prettier in check mode
+- `script/frontend-fmt` — format everything prettier understands (writes)
+- `script/frontend-fmt-check` — check prettier formatting (read-only)
+- `script/frontend-check` — the frontend half of `script/check`, shimmed by
+  `make frontend-check` and used by `Dockerfile`, whose build stage is a node
+  image with no Go toolchain. Its mirror `make backend-check` shims to
+  `backend/script/check`
+- `script/docker` — build both images, tagged via `script/projectname`:
+  `netwatch` from `Dockerfile` and `netwatch-server` from `Dockerfile.backend`
+- `script/cibuild` — CI entrypoint: builds both images; the only build step in
+  the Gitea workflow
+- `script/precommit` — run by the git pre-commit hook; runs `script/check`, so a
+  commit is gated on both halves of the repo
+- `script/install-precommit` — install the git pre-commit hook; this is the
+  repo's only pre-commit hook installer
 
-## Responsive layout
+The backend's scripts are shimmed by `backend/Makefile` and are also called by
+the root scripts above:
 
-The narrow-viewport layout lives in the `max-width: 768px` media block in
-`src/styles.css`. It is verified automatically by `make frontend-viewport-test`,
-which drives a digest-pinned headless Chrome against the built `dist/` and
-asserts on computed layout at widths derived from that CSS — one pixel either
-side of every breakpoint it declares, plus a 320px floor, a desktop baseline and
-two landscape sizes. See [test/viewport/README.md](test/viewport/README.md) for
-what it covers and what it genuinely cannot.
+- `backend/script/build` — compile `netwatch-server` with version and
+  architecture stamped in
+- `backend/script/test` — run the Go tests under a 30-second timeout
+- `backend/script/lint` — assert `.golangci.yml` still matches its pinned
+  sha256, then run golangci-lint
+- `backend/script/fmt` — format the Go sources (writes)
+- `backend/script/fmt-check` — check Go formatting (read-only)
+- `backend/script/check` — run the backend's test, lint, and fmt-check
+- `backend/script/run` — build and run the server locally
+- `backend/script/clean` — remove build artifacts
 
 ## Rationale
 

TODO.md

@@ -22,12 +22,20 @@ files, so merging it also closes most compliance gaps.
 
 # Completed Steps
 
-- 2026-08-09: automated responsive-layout harness
-  (`make frontend-viewport-test`): digest-pinned headless Chrome driven over CDP
-  against the built `dist/`, viewport widths derived from the breakpoints in
-  `src/styles.css` (#13). Every check carries a presence guard so none of them
-  can pass against a page it is not actually measuring. Found two real layout
-  defects, filed as #42 and #43
+- 2026-08-09: unified the gate: the root `make check` now covers the Go backend
+  as well as the frontend, the backend moved onto scripts-to-rule-them-all
+  (`backend/script/*` with `backend/Makefile` as thin shims), the duplicate
+  pre-commit hook installer in `backend/Makefile` was removed, `script/cibuild`
+  now builds both images as the workflow's only build step, and
+  `script/bootstrap` provisions the backend toolchain (pinned, hash-verified Go
+  and golangci-lint) so a fresh clone can pass the widened gate. Bootstrap
+  matches the Go pin rather than treating it as a floor, because the pinned
+  golangci-lint cannot analyse packages built by a newer Go; it links only into
+  `~/.local/bin`, never a system-wide prefix, and refuses to replace anything it
+  did not create; and it exits non-zero rather than reporting success when the
+  tools on the caller's `PATH` are not the pinned ones — `gofmt` included, held
+  to the same version agreement as `go` and relinked on every run so a deleted
+  link cannot leave another Go's `gofmt` gating the repo
 - 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints, Makefile
   shims, README Entrypoints section
 - 2026-02-27: backend with buffered zstd-compressed report storage; CI workflow
@@ -45,9 +53,6 @@ files, so merging it also closes most compliance gaps.
 
 # Future Steps
 
-- Fix the two layout defects the viewport harness found (#42 horizontal overflow
-  at 320px, #43 tap targets below 44x44), then wire
-  `script/frontend-viewport-test` into CI as its own step
 - Compliance top-up as one small commit: add .editorconfig and add the hooks
   target to the Makefile
 - After merge, confirm .gitea/workflows/check.yml is on main and CI is green

backend/Makefile

@@ -1,53 +1,38 @@
-UNAME_S := $(shell uname -s)
-VERSION := $(shell git describe --always --dirty)
-BUILDARCH := $(shell uname -m)
-BINARY := netwatch-server
+# Standard targets are thin shims; the implementations live in
+# backend/script/ per the scripts-to-rule-them-all pattern (see the
+# Entrypoints section of README.md).
+#
+# There is no `hooks` target here: the repo has exactly one pre-commit
+# hook installer, the root `script/install-precommit`, and the hook it
+# installs gates both halves of the repo. There is no `docker` target
+# either: the backend image is built from Dockerfile.backend with the
+# repo root as its context, so it belongs to the root `make docker` and
+# `script/cibuild`.
 
-GOLDFLAGS += -X main.Version=$(VERSION)
-GOLDFLAGS += -X main.Buildarch=$(BUILDARCH)
-
-ifeq ($(UNAME_S),Darwin)
-	GOFLAGS := -ldflags "$(GOLDFLAGS)"
-else
-	GOFLAGS = -ldflags "-linkmode external -extldflags -static $(GOLDFLAGS)"
-endif
-
-.PHONY: all build test lint fmt fmt-check check docker hooks run clean
+.PHONY: all build test lint fmt fmt-check check run clean
 
 all: build
 
-build: ./$(BINARY)
-
-./$(BINARY): $(shell find . -name '*.go' -type f) go.mod go.sum
-	go build -o $@ $(GOFLAGS) ./cmd/netwatch-server/
+build:
+	@script/build
 
 test:
-	timeout 30 go test ./...
+	@script/test
 
 lint:
-	golangci-lint run ./...
+	@script/lint
 
 fmt:
-	go fmt ./...
+	@script/fmt
 
 fmt-check:
-	@test -z "$$(gofmt -l .)" || \
-		(echo "Files not formatted:"; gofmt -l .; exit 1)
+	@script/fmt-check
 
-check: test lint fmt-check
+check:
+	@script/check
 
-docker:
-	timeout 300 docker build -t netwatch-server -f ../Dockerfile.backend ..
-
-hooks:
-	@printf '#!/bin/sh\ncd backend && make check\n' > \
-		$$(git rev-parse --show-toplevel)/.git/hooks/pre-commit
-	@chmod +x \
-		$$(git rev-parse --show-toplevel)/.git/hooks/pre-commit
-	@echo "Pre-commit hook installed"
-
-run: build
-	./$(BINARY)
+run:
+	@script/run
 
 clean:
-	rm -f ./$(BINARY)
+	@script/clean

backend/README.md

@@ -4,18 +4,54 @@ SPA and persists them as zstd-compressed JSONL files on disk.
 
 ## Getting Started
 
+From this directory (`backend/`):
+
 ```bash
 # Build and run locally
 make run
 
-# Run tests, lint, and format check
+# Run the backend's tests, lint, and format check
 make check
+```
 
-# Docker
-docker build -t netwatch-server .
+From the repo root, one directory up — `Dockerfile.backend` lives there and its
+build context is the repo root, so there is no `docker` target here:
+
+```bash
+# Build both images, including netwatch-server
+make docker
+
+# Run the backend image
 docker run -p 8080:8080 netwatch-server
 ```
 
+## Entrypoints
+
+This project follows the same
+[Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
+pattern as the repo root: the implementations live in `backend/script/` and the
+targets in `backend/Makefile` are thin shims that call them. The repo root's
+`script/test`, `script/lint`, `script/fmt` and `script/fmt-check` call these
+too, so the root `make check` covers the backend.
+
+- `script/build` — compile `netwatch-server` with the version and architecture
+  stamped in via ldflags (statically linked on Linux)
+- `script/test` — run the Go tests under a 30-second timeout
+- `script/lint` — assert `.golangci.yml` still matches its pinned sha256, then
+  run golangci-lint
+- `script/fmt` — format the Go sources (writes)
+- `script/fmt-check` — check Go formatting (read-only)
+- `script/check` — run test, lint, and fmt-check
+- `script/run` — build and run the server locally
+- `script/clean` — remove build artifacts
+
+There is deliberately no `hooks` target here: the repo has exactly one
+pre-commit hook installer, the root `script/install-precommit`, and the hook it
+installs runs the root `script/check`, which gates both halves of the repo.
+There is no `docker` target either: `Dockerfile.backend` lives at the repo root
+and builds with the repo root as its context, so the backend image is built by
+the root `make docker` and by `script/cibuild`.
+
 ## Rationale
 
 The NetWatch frontend collects latency measurements from the browser but has no

backend/script/build

@@ -0,0 +1,27 @@
+#!/bin/sh
+# script/build: compile the netwatch-server binary into the backend
+# project root. Version and architecture are stamped into the binary via
+# ldflags; on Linux the binary is statically linked.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+BINARY="netwatch-server"
+
+main() {
+    cd "$ROOT"
+
+    # git describe fails outside a working repo (e.g. a source tarball),
+    # which must not abort the build.
+    version="$(git describe --always --dirty 2>/dev/null || echo unknown)"
+    buildarch="$(uname -m)"
+
+    ldflags="-X main.Version=$version -X main.Buildarch=$buildarch"
+    if [ "$(uname -s)" != "Darwin" ]; then
+        ldflags="-linkmode external -extldflags -static $ldflags"
+    fi
+
+    go build -o "$BINARY" -ldflags "$ldflags" ./cmd/netwatch-server/
+}
+
+main "$@"

backend/script/check

@@ -0,0 +1,16 @@
+#!/bin/sh
+# script/check: run all backend checks (test, lint, fmt-check). Must not
+# modify any files. The root script/check calls this, so the repo-wide
+# gate covers the backend.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    "$ROOT/script/test"
+    "$ROOT/script/lint"
+    "$ROOT/script/fmt-check"
+}
+
+main "$@"

backend/script/clean

@@ -0,0 +1,12 @@
+#!/bin/sh
+# script/clean: remove build artifacts.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    rm -f netwatch-server
+}
+
+main "$@"

backend/script/fmt

@@ -0,0 +1,12 @@
+#!/bin/sh
+# script/fmt: format all Go sources in the backend (writes).
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    go fmt ./...
+}
+
+main "$@"

backend/script/fmt-check

@@ -0,0 +1,18 @@
+#!/bin/sh
+# script/fmt-check: check Go formatting (read-only). Same scope as
+# script/fmt, but fails instead of writing.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    unformatted="$(gofmt -l .)"
+    if [ -n "$unformatted" ]; then
+        echo "Files not formatted:"
+        echo "$unformatted"
+        exit 1
+    fi
+}
+
+main "$@"

backend/script/lint

@@ -0,0 +1,56 @@
+#!/bin/sh
+# script/lint: run the Go linter over the backend.
+#
+# .golangci.yml is standardized org-wide and must never be edited here
+# (REPO_POLICIES.md). Its last silent drift replaced the v2 schema with
+# v1 keys, which left every threshold in the file inert while the build
+# stayed green. This script therefore asserts the file still matches the
+# pinned copy byte for byte before the linter runs. The check is a local
+# hash comparison: no network, no remote schema, nothing unpinned in the
+# build path.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# sha256 of the pinned backend/.golangci.yml.
+#
+# PROVISIONAL. The hash below is the file currently on main, which is
+# the schema-invalid v1-keyed config described above: it is pinned only
+# so this branch and main stay green, NOT because it is canonical.
+#
+# The canonical org-wide .golangci.yml is
+# 021cc83f4e6fc7c31b95b34b846723dfcf20b66b7baeea1dc40406e643346bcb,
+# and PR #31 replaces backend/.golangci.yml with it. When #31 lands,
+# GOLANGCI_CONFIG_SHA256 must be updated to that hash in the same
+# commit. Until then, do not treat the pinned file as the standard.
+GOLANGCI_CONFIG_SHA256="33ba2bf7fe4a44779d09b0fb31d6daf03685f8dc9d2bc417f963d7aabb0d17dc"
+
+# sha256 <file>: print the file's sha256, coreutils or Darwin/busybox.
+sha256() {
+    if command -v sha256sum >/dev/null 2>&1; then
+        sha256sum "$1" | cut -d' ' -f1
+    else
+        shasum -a 256 "$1" | cut -d' ' -f1
+    fi
+}
+
+check_config_hash() {
+    actual="$(sha256 .golangci.yml)"
+    if [ "$actual" != "$GOLANGCI_CONFIG_SHA256" ]; then
+        echo ".golangci.yml has drifted from the pinned config."
+        echo "  expected $GOLANGCI_CONFIG_SHA256"
+        echo "  actual   $actual"
+        echo "Restore it verbatim from sneak/prompts; do not edit it."
+        echo "Only update GOLANGCI_CONFIG_SHA256 in this script when the"
+        echo "pinned config is deliberately replaced with a new standard."
+        exit 1
+    fi
+}
+
+main() {
+    cd "$ROOT"
+    check_config_hash
+    golangci-lint run ./...
+}
+
+main "$@"

backend/script/run

@@ -0,0 +1,13 @@
+#!/bin/sh
+# script/run: build and run netwatch-server locally.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    "$ROOT/script/build"
+    exec ./netwatch-server "$@"
+}
+
+main "$@"

backend/script/test

@@ -0,0 +1,12 @@
+#!/bin/sh
+# script/test: run the backend test suite.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    timeout 30 go test ./...
+}
+
+main "$@"

package.json

@@ -14,7 +14,6 @@
         "autoprefixer": "^10.4.23",
         "postcss": "^8.5.6",
         "prettier": "^3.8.1",
-        "puppeteer-core": "25.5.0",
         "tailwindcss": "^4.1.18",
         "vite": "^7.3.1"
     }

script/bootstrap

@@ -5,11 +5,50 @@
 # or apk (detected in that order); assumes nothing is present. Node is
 # used directly if installed; otherwise it is installed at a pinned
 # version via nvm (installing nvm itself first, from a hash-verified
-# release archive, never curl | sh).
+# release archive, never curl | sh). Go is used directly only if its
+# version falls inside the pinned window described at GO_MAX_MINOR below
+# -- a newer Go is ignored, not preferred -- and golangci-lint is
+# installed at the exact pinned version; both come from hash-verified
+# official release archives, never an install script.
+#
+# The backend's toolchain is bootstrapped here because script/check runs
+# backend/script/test and backend/script/lint, so a machine that cannot
+# run go and golangci-lint cannot pass the repo-wide gate or the
+# pre-commit hook that script/setup installs.
+#
+# Anything installed outside the system package manager is symlinked
+# into ~/.local/bin, so a later `make check` in a plain shell finds it.
+# nvm only puts node on PATH for shells that source nvm.sh, which
+# neither make nor the git hook does.
+#
+# Three rules govern what this script is allowed to touch:
+#
+#   1. Everything it installs itself lands under $HOME, using $TMPDIR
+#      only for scratch downloads it then deletes. The one exception is
+#      the system package manager, which it shells out to for base
+#      tooling (see pkg_install) and which owns those paths already. A
+#      per-repo bootstrap has no business writing to /usr/local/bin, a
+#      Homebrew prefix, or any other system-wide location behind that
+#      package manager's back.
+#   2. It never replaces something it did not create. Only a symlink
+#      that already points into one of its own managed directories is
+#      overwritten; anything else is left alone and bootstrap exits
+#      non-zero telling you what to remove.
+#   3. It never reports success while the tools a later `make check`
+#      would pick up are not the ones it provisioned. If it cannot
+#      guarantee the pinned toolchain wins on your PATH, it exits
+#      non-zero rather than leaving you a green bootstrap and a broken
+#      gate.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+# The PATH as the caller had it, captured before ensure_bin_dir amends
+# it. verify_toolchain checks against this rather than against the PATH
+# this script builds for itself, so what it reports is what a later
+# `make check` in the user's own shell will actually resolve.
+ORIG_PATH="$PATH"
+
 # Pinned versions, 2026-07-07
 NODE_VERSION="22.17.0"
 NVM_VERSION="0.40.3"
@@ -17,9 +56,58 @@ NVM_VERSION="0.40.3"
 NVM_SHA256="5f4d6aaa04a177dc93c985e31dbc411ab6b8c6e1e21d8015dbc1372625fcd1d0"
 YARN_VERSION="1.22.22"
 
+# Go 1.25.7 (2026-08-09). This is the toolchain inside the pinned
+# golang:1.25-alpine builder of Dockerfile.backend, so a local build
+# uses the same compiler CI does.
+#
+# The Go pin is a compatibility constraint to match, not a floor to
+# clear. golangci-lint links go/types from the Go release it was built
+# with, and go/types refuses to load packages compiled by a newer Go:
+# with the pinned linter (built with go1.25.4) and a host Go 1.26,
+# `make check` dies with
+#
+#     panic: file requires newer Go version go1.26
+#            (application built with go1.25)
+#
+# So an already-installed go is reused only inside a window:
+# GO_MIN_VERSION is the floor from backend/go.mod, and GO_MAX_MINOR is
+# the major.minor of the Go the pinned golangci-lint was built with.
+# Anything outside that window is ignored and GO_VERSION is installed
+# instead. GO_MAX_MINOR is therefore coupled to GOLANGCI_LINT_VERSION
+# below and must be revisited whenever that pin moves; `golangci-lint
+# version` prints the "built with goX.Y.Z" it needs.
+GO_VERSION="1.25.7"
+GO_MIN_VERSION="1.25.5"
+GO_MAX_MINOR="1.25"
+
+# golangci-lint 2.7.2 (2026-08-09). MUST stay equal to the golangci-lint
+# pinned in Dockerfile.backend (currently commit
+# 9f61b0f53f80672872fced07b6874397c3ed197b, which is tag v2.7.2), so a
+# local `make lint` and CI's in-image `make check` report the same
+# findings.
+#
+# Reconciliation note: PR #31 moves Dockerfile.backend to golangci-lint
+# v2.12.2, commit c0d3ddc9cf3faa61a4e378e879ece580256d76e5. When that
+# lands, GOLANGCI_LINT_VERSION and every hash in golangci_lint_sha256()
+# below must be updated to the v2.12.2 release archives in the same
+# commit, or local and CI will disagree. GO_MAX_MINOR must move with
+# it, to the major.minor that release reports as "built with".
+GOLANGCI_LINT_VERSION="2.7.2"
+
+# Where hash-verified archives are unpacked. Version-scoped, so bumping
+# a pin installs alongside the old copy instead of half-overwriting it.
+# Filled in by main() from script/projectname. TOOLCHAIN is also the
+# ownership boundary used by link_bin: a symlink pointing inside it is
+# one this script created and may replace.
+TOOLCHAIN=""
+GO_DIR=""
+GOLANGCI_LINT_DIR=""
+
 PKGMGR=""
 SUDO=""
 APT_UPDATED=""
+BIN_DIR=""
+NODE_BIN=""
 
 detect_pkgmgr() {
     [ -n "$PKGMGR" ] && return 0
@@ -79,6 +167,119 @@ verify_sha256() {
     fi
 }
 
+# fetch_verified <url> <expected-hash> <dest>: download a release
+# archive and check it against a hash hardcoded in this script before
+# anything is unpacked or run. Never pipe a remote script to a shell.
+fetch_verified() {
+    if missing curl; then pkg_install curl curl curl curl; fi
+    curl -fsSL -o "$3" "$1"
+    verify_sha256 "$3" "$2"
+}
+
+# platform: <os>-<arch> as used in the Go and golangci-lint release
+# archive filenames.
+platform() {
+    plat_os="$(uname -s)"
+    plat_arch="$(uname -m)"
+    case "$plat_os" in
+        Linux) plat_os="linux" ;;
+        Darwin) plat_os="darwin" ;;
+        *)
+            echo "bootstrap: unsupported OS $plat_os" >&2
+            exit 1
+            ;;
+    esac
+    case "$plat_arch" in
+        x86_64 | amd64) plat_arch="amd64" ;;
+        aarch64 | arm64) plat_arch="arm64" ;;
+        *)
+            echo "bootstrap: unsupported architecture $plat_arch" >&2
+            exit 1
+            ;;
+    esac
+    echo "$plat_os-$plat_arch"
+}
+
+# ver_ge <have> <want>: succeed if dotted version <have> is at least
+# <want>, comparing up to three numeric components.
+ver_ge() {
+    awk -v have="$1" -v want="$2" '
+        BEGIN {
+            n = split(have, h, ".")
+            m = split(want, w, ".")
+            for (i = 1; i <= 3; i++) {
+                hv = (i <= n) ? h[i] + 0 : 0
+                wv = (i <= m) ? w[i] + 0 : 0
+                if (hv > wv) exit 0
+                if (hv < wv) exit 1
+            }
+            exit 0
+        }'
+}
+
+# ensure_bin_dir: the directory provisioned tools are linked into. It is
+# always ~/.local/bin: per-user, never a system-wide or package-manager
+# prefix. It is put at the front of PATH for the rest of this run, and
+# reported if the caller's own PATH did not already contain it.
+ensure_bin_dir() {
+    [ -n "$BIN_DIR" ] && return 0
+    BIN_DIR="$HOME/.local/bin"
+    mkdir -p "$BIN_DIR"
+    case "$PATH" in
+        "$BIN_DIR":*) ;;
+        *)
+            PATH="$BIN_DIR:$PATH"
+            export PATH
+            ;;
+    esac
+    case ":$ORIG_PATH:" in
+        *":$BIN_DIR:"*) ;;
+        *)
+            echo "bootstrap: add $BIN_DIR to the front of your PATH, e.g." >&2
+            echo "  export PATH=\"\$HOME/.local/bin:\$PATH\"" >&2
+            ;;
+    esac
+}
+
+# owned_path <path>: true when <path> lies inside a directory this
+# script provisions, i.e. a link to it is one this script created and
+# may replace. Everything else belongs to the user or to a package
+# manager and is never touched.
+owned_path() {
+    case "$1" in
+        "$TOOLCHAIN"/*) return 0 ;;
+        "$HOME"/.nvm/*) return 0 ;;
+        *) return 1 ;;
+    esac
+}
+
+# refuse_clobber <path> <what>: report that <path> is not ours and stop.
+refuse_clobber() {
+    echo "bootstrap: $1 already exists and $2." >&2
+    echo "  Refusing to replace something this script did not create." >&2
+    echo "  Remove or rename it and re-run bootstrap." >&2
+    exit 1
+}
+
+# link_bin <target> <name>: idempotently expose one provisioned binary
+# on PATH. Only an existing symlink into one of our own directories is
+# replaced; a regular file, a directory, or a symlink pointing anywhere
+# else is left intact and bootstrap fails.
+link_bin() {
+    ensure_bin_dir
+    link="$BIN_DIR/$2"
+    if [ -L "$link" ]; then
+        existing="$(readlink "$link")"
+        if ! owned_path "$existing"; then
+            refuse_clobber "$link" \
+                "is a symlink to $existing, outside this repo's toolchain"
+        fi
+    elif [ -e "$link" ]; then
+        refuse_clobber "$link" "is not a symlink"
+    fi
+    ln -sfn "$1" "$link"
+}
+
 # nvm is a bash script; run a command in a bash with nvm loaded
 nvm_sh() {
     bash -c ". \"\$HOME/.nvm/nvm.sh\" && $*"
@@ -91,9 +292,9 @@ ensure_nvm() {
     if missing curl; then pkg_install curl curl curl curl; fi
     if missing git; then pkg_install git git git git; fi
     tmp="$(mktemp -d)"
-    curl -fsSL -o "$tmp/nvm.tar.gz" \
-        "https://github.com/nvm-sh/nvm/archive/refs/tags/v${NVM_VERSION}.tar.gz"
-    verify_sha256 "$tmp/nvm.tar.gz" "$NVM_SHA256"
+    fetch_verified \
+        "https://github.com/nvm-sh/nvm/archive/refs/tags/v${NVM_VERSION}.tar.gz" \
+        "$NVM_SHA256" "$tmp/nvm.tar.gz"
     mkdir -p "$HOME/.nvm"
     tar -xzf "$tmp/nvm.tar.gz" -C "$HOME/.nvm" --strip-components=1
     rm -rf "$tmp"
@@ -103,18 +304,37 @@ ensure_node() {
     if ! missing node; then return 0; fi
     ensure_nvm
     nvm_sh "nvm install $NODE_VERSION"
+    NODE_BIN="$HOME/.nvm/versions/node/v$NODE_VERSION/bin"
+    for nb in node npm npx corepack; do
+        if [ -e "$NODE_BIN/$nb" ]; then link_bin "$NODE_BIN/$nb" "$nb"; fi
+    done
 }
 
+# ensure_yarn: yarn comes from corepack. Left to itself, `corepack
+# enable` writes its shims next to the corepack binary it resolved, and
+# it writes four of them (yarn, yarnpkg, pnpm, pnpx), not the one asked
+# for. --install-directory keeps all four inside this repo's own
+# toolchain directory, and only yarn is then linked onto PATH. The
+# no-corepack fallback likewise installs into a per-user npm prefix
+# under the toolchain directory instead of npm's global one. Nothing
+# here writes outside $HOME.
 ensure_yarn() {
     if ! missing yarn; then return 0; fi
+    yarn_bin="$TOOLCHAIN/corepack-shims"
+    mkdir -p "$yarn_bin"
     if ! missing corepack; then
-        corepack enable
+        corepack enable --install-directory "$yarn_bin"
         corepack prepare "yarn@$YARN_VERSION" --activate
     elif [ -s "$HOME/.nvm/nvm.sh" ]; then
-        nvm_sh "nvm use $NODE_VERSION >/dev/null && corepack enable && \
+        nvm_sh "nvm use $NODE_VERSION >/dev/null && \
+            corepack enable --install-directory \"$yarn_bin\" && \
             corepack prepare yarn@$YARN_VERSION --activate"
     else
-        npm install -g "yarn@$YARN_VERSION"
+        yarn_bin="$TOOLCHAIN/npm-global/bin"
+        npm install -g --prefix "$TOOLCHAIN/npm-global" "yarn@$YARN_VERSION"
+    fi
+    if [ -e "$yarn_bin/yarn" ]; then
+        link_bin "$yarn_bin/yarn" yarn
     fi
 }
 
@@ -127,9 +347,247 @@ install_js_deps() {
     fi
 }
 
+# go_sha256 <platform>: sha256 of
+# https://go.dev/dl/go1.25.7.<platform>.tar.gz, from the signed release
+# index at https://go.dev/dl/?mode=json (2026-08-09).
+go_sha256() {
+    case "$1" in
+        linux-amd64)
+            echo "12e6d6a191091ae27dc31f6efc630e3a3b8ba409baf3573d955b196fdf086005"
+            ;;
+        linux-arm64)
+            echo "ba611a53534135a81067240eff9508cd7e256c560edd5d8c2fef54f083c07129"
+            ;;
+        darwin-amd64)
+            echo "bf5050a2152f4053837b886e8d9640c829dbacbc3370f913351eb0904cb706f5"
+            ;;
+        darwin-arm64)
+            echo "ff18369ffad05c57d5bed888b660b31385f3c913670a83ef557cdfd98ea9ae1b"
+            ;;
+        *)
+            echo "bootstrap: no pinned Go archive hash for $1" >&2
+            exit 1
+            ;;
+    esac
+}
+
+# go_ok: an already-installed go is acceptable only inside the window
+# described at GO_MAX_MINOR: at least GO_MIN_VERSION, and no newer in
+# major.minor than the Go the pinned golangci-lint was built with. A
+# newer host Go is not "good enough", it makes `make check` panic, so it
+# is treated exactly like a missing one.
+go_ok() {
+    if missing go; then return 1; fi
+    have="$(go version 2>/dev/null | awk '{print $3}')"
+    have="${have#go}"
+    [ -n "$have" ] || return 1
+    ver_ge "$have" "$GO_MIN_VERSION" || return 1
+    ver_ge "$GO_MAX_MINOR" "$(echo "$have" | cut -d. -f1,2)"
+}
+
+# gofmt_ok: gofmt is a gate tool -- backend/script/fmt-check runs it --
+# and its output is not guaranteed byte-identical across Go releases, so
+# a gofmt from a different release than the go that compiles the code is
+# treated exactly like a missing one, the same way a mismatched
+# golangci-lint is. `go version <file>` prints the toolchain a Go binary
+# was built with, so this compares the gofmt that resolves on PATH
+# against the go that resolves on PATH, without depending on where
+# either one lives. Anything it cannot read -- no go to ask, gofmt
+# absent, not a Go binary -- fails closed.
+gofmt_ok() {
+    if missing go; then return 1; fi
+    if missing gofmt; then return 1; fi
+    go_have="$(go version 2>/dev/null | awk '{print $3}')"
+    [ -n "$go_have" ] || return 1
+    fmt_have="$(go version "$(command -v gofmt)" 2>/dev/null | awk '{print $NF}')"
+    [ "$fmt_have" = "$go_have" ]
+}
+
+# ensure_go: reuse the host toolchain only when the go on PATH is inside
+# the window AND a gofmt from that same release is on PATH with it. Both
+# link_bin calls sit outside that early return, so whenever the pinned
+# toolchain is the one in use they run on every bootstrap, not only on
+# the run that unpacked the archive: a deleted or never-created gofmt
+# link is restored rather than silently left to some other Go's gofmt.
+ensure_go() {
+    if go_ok && gofmt_ok; then return 0; fi
+    if [ ! -x "$GO_DIR/bin/go" ]; then
+        plat="$(platform)"
+        tmp="$(mktemp -d)"
+        fetch_verified \
+            "https://go.dev/dl/go${GO_VERSION}.${plat}.tar.gz" \
+            "$(go_sha256 "$plat")" "$tmp/go.tar.gz"
+        rm -rf "$GO_DIR.partial"
+        mkdir -p "$GO_DIR.partial"
+        tar -xzf "$tmp/go.tar.gz" -C "$GO_DIR.partial" --strip-components=1
+        rm -rf "$GO_DIR"
+        mv "$GO_DIR.partial" "$GO_DIR"
+        rm -rf "$tmp"
+    fi
+    link_bin "$GO_DIR/bin/go" go
+    link_bin "$GO_DIR/bin/gofmt" gofmt
+}
+
+# golangci_lint_sha256 <platform>: sha256 of the golangci-lint 2.7.2
+# release archive for that platform, from
+# https://github.com/golangci/golangci-lint/releases/download/v2.7.2/golangci-lint-2.7.2-checksums.txt
+# (2026-08-09).
+golangci_lint_sha256() {
+    case "$1" in
+        linux-amd64)
+            echo "ce46a1f1d890e7b667259f70bb236297f5cf8791a9b6b98b41b283d93b5b6e88"
+            ;;
+        linux-arm64)
+            echo "7028e810837722683dab679fb121336cfa303fecff39dfe248e3e36bc18d941b"
+            ;;
+        darwin-amd64)
+            echo "6966554840a02229a14c52641bc38c2c7a14d396f4c59ba0c7c8bb0675ca25c9"
+            ;;
+        darwin-arm64)
+            echo "6ce86a00e22b3709f7b994838659c322fdc9eae09e263db50439ad4f6ec5785c"
+            ;;
+        *)
+            echo "bootstrap: no pinned golangci-lint archive hash for $1" >&2
+            exit 1
+            ;;
+    esac
+}
+
+# golangci_lint_ok: unlike go, this must be the exact pinned version.
+# A different version reports a different set of findings, so local
+# results would stop matching what Dockerfile.backend gates on.
+golangci_lint_ok() {
+    if missing golangci-lint; then return 1; fi
+    have="$(golangci-lint version 2>&1 | awk '
+        {
+            for (i = 1; i < NF; i++) {
+                if ($i == "version") {
+                    v = $(i + 1)
+                    sub(/^v/, "", v)
+                    print v
+                    exit
+                }
+            }
+        }')"
+    [ "$have" = "$GOLANGCI_LINT_VERSION" ]
+}
+
+ensure_golangci_lint() {
+    if golangci_lint_ok; then return 0; fi
+    if [ ! -x "$GOLANGCI_LINT_DIR/golangci-lint" ]; then
+        plat="$(platform)"
+        base="golangci-lint-${GOLANGCI_LINT_VERSION}-${plat}"
+        tmp="$(mktemp -d)"
+        fetch_verified \
+            "https://github.com/golangci/golangci-lint/releases/download/v${GOLANGCI_LINT_VERSION}/${base}.tar.gz" \
+            "$(golangci_lint_sha256 "$plat")" "$tmp/golangci-lint.tar.gz"
+        mkdir -p "$tmp/x"
+        tar -xzf "$tmp/golangci-lint.tar.gz" -C "$tmp/x" --strip-components=1
+        rm -rf "$GOLANGCI_LINT_DIR.partial"
+        mkdir -p "$GOLANGCI_LINT_DIR.partial"
+        cp "$tmp/x/golangci-lint" "$GOLANGCI_LINT_DIR.partial/golangci-lint"
+        chmod +x "$GOLANGCI_LINT_DIR.partial/golangci-lint"
+        rm -rf "$GOLANGCI_LINT_DIR"
+        mv "$GOLANGCI_LINT_DIR.partial" "$GOLANGCI_LINT_DIR"
+        rm -rf "$tmp"
+    fi
+    link_bin "$GOLANGCI_LINT_DIR/golangci-lint" golangci-lint
+}
+
+# verify_toolchain: bootstrap must not exit 0 while the tools the gate
+# will actually run are not the provisioned ones. Everything above only
+# guarantees the right tools exist and are linked into $BIN_DIR; if
+# something earlier on the caller's PATH shadows them, `make check` --
+# and the pre-commit hook script/setup installs -- still break, and a
+# warning buried in a long bootstrap log is not enough. So the checks
+# re-run against the PATH the caller will have (theirs, plus $BIN_DIR at
+# the front if bootstrap had to ask for it), and a failure is fatal.
+#
+# Every gate tool that has a version constraint is checked with the same
+# predicate its install used -- go_ok, gofmt_ok, golangci_lint_ok -- not
+# with a bare presence test, because a wrong-version gate tool produces
+# different results from the one CI runs, which is the failure this
+# function exists to prevent. node and yarn have no pinned version to
+# disagree about, so presence is the whole constraint for them.
+verify_toolchain() {
+    # BIN_DIR is only set once something needed linking, but the remedy
+    # text must name a real directory in every reachable state, so fall
+    # back to the one ensure_bin_dir would have chosen.
+    bin_dir="${BIN_DIR:-$HOME/.local/bin}"
+
+    # Model the PATH the caller will actually have: their own, plus
+    # $BIN_DIR at the front only if bootstrap linked something there and
+    # therefore told them to add it.
+    verify_path="$ORIG_PATH"
+    if [ -n "$BIN_DIR" ]; then
+        case ":$ORIG_PATH:" in
+            *":$BIN_DIR:"*) ;;
+            *) verify_path="$BIN_DIR:$ORIG_PATH" ;;
+        esac
+    fi
+
+    saved_path="$PATH"
+    PATH="$verify_path"
+    export PATH
+    bad=""
+    go_ok || bad="$bad go"
+    gofmt_ok || bad="$bad gofmt"
+    golangci_lint_ok || bad="$bad golangci-lint"
+    for t in node yarn; do
+        if missing "$t"; then bad="$bad $t"; fi
+    done
+    PATH="$saved_path"
+    export PATH
+
+    [ -z "$bad" ] && return 0
+
+    # Two different faults land here and they need different remedies: a
+    # tool that resolves but is the wrong build is being shadowed, and
+    # telling the user to fix PATH is right; a tool that does not resolve
+    # at all is not being shadowed by anything, and saying so would send
+    # them hunting for a conflict that does not exist.
+    echo "bootstrap: the toolchain on your PATH cannot run the gate." >&2
+    wrong=""
+    absent=""
+    for t in $bad; do
+        where="$(
+            export PATH="$verify_path"
+            command -v "$t" 2>/dev/null || true
+        )"
+        if [ -n "$where" ]; then
+            echo "  $t: $where (wrong version)" >&2
+            wrong="$wrong $t"
+        else
+            echo "  $t: not found" >&2
+            absent="$absent $t"
+        fi
+    done
+    echo "  The pinned toolchain is linked into $bin_dir." >&2
+    if [ -n "$wrong" ]; then
+        echo "  The tools shown with a path resolve to a build this" >&2
+        echo "  script did not provision: something earlier on your PATH" >&2
+        echo "  shadows $bin_dir. Put $bin_dir first in" >&2
+        echo "  PATH, or remove the conflicting tool, then re-run." >&2
+    fi
+    if [ -n "$absent" ]; then
+        echo "  The tools shown as not found are on no directory of your" >&2
+        echo "  PATH at all, so nothing is shadowing them. Add $bin_dir" >&2
+        echo "  to PATH and re-run; if they are still not found after" >&2
+        echo "  that, bootstrap failed to install them and that is a bug" >&2
+        echo "  in this script, not in your environment." >&2
+    fi
+    echo "  Failing rather than leaving you a bootstrap that reports" >&2
+    echo "  success and a \`make check\` that does not run." >&2
+    exit 1
+}
+
 main() {
     cd "$ROOT"
 
+    TOOLCHAIN="$HOME/.local/share/$("$ROOT/script/projectname")/toolchain"
+    GO_DIR="$TOOLCHAIN/go-$GO_VERSION"
+    GOLANGCI_LINT_DIR="$TOOLCHAIN/golangci-lint-$GOLANGCI_LINT_VERSION"
+
     if missing make; then pkg_install gnumake make make make; fi
     if missing git; then pkg_install git git git git; fi
 
@@ -137,6 +595,11 @@ main() {
     ensure_yarn
     install_js_deps
 
+    ensure_go
+    ensure_golangci_lint
+
+    verify_toolchain
+
     echo "bootstrap complete"
 }
 

script/check

@@ -1,14 +1,16 @@
 #!/bin/sh
-# script/check: run all checks (test, lint, fmt-check). Our own
-# extension to scripts-to-rule-them-all. Must not modify any files.
+# script/check: run all checks (test, lint, fmt-check) across the whole
+# repo, frontend and backend. Our own extension to
+# scripts-to-rule-them-all. Must not modify any files.
 set -eu
 
-SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
-    "$SCRIPT_DIR/test"
-    "$SCRIPT_DIR/lint"
-    "$SCRIPT_DIR/fmt-check"
+    cd "$ROOT"
+    "$ROOT/script/test"
+    "$ROOT/script/lint"
+    "$ROOT/script/fmt-check"
 }
 
 main "$@"

script/cibuild

@@ -1,13 +1,24 @@
 #!/bin/sh
-# script/cibuild: run the CI build. The Dockerfile runs make check, so
-# a successful build implies all checks pass.
+# script/cibuild: run the CI build. It builds every image in the repo:
+# the frontend image from Dockerfile and the backend image from
+# Dockerfile.backend. Each Dockerfile runs its half of make check as a
+# build step, so a successful cibuild implies the whole repo is green.
+# This is the only build step the Gitea workflow runs.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
+# build_image <dockerfile>: build one image from the repo root context.
+# Every docker build CI performs goes through here, so build-wide flags
+# only ever have to be added in one place.
+build_image() {
+    timeout 300 docker build -f "$1" .
+}
+
 main() {
     cd "$ROOT"
-    docker build .
+    build_image Dockerfile
+    build_image Dockerfile.backend
 }
 
 main "$@"

script/docker

@@ -1,14 +1,16 @@
 #!/bin/sh
-# script/docker: build the Docker image tagged with the project name.
-# The tag comes from script/projectname.
+# script/docker: build the repo's Docker images, tagged from
+# script/projectname: the frontend image as <name> and the backend image
+# as <name>-server. Both build from the repo root as their context.
 set -eu
 
-SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
-ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    timeout 300 docker build -t "$("$SCRIPT_DIR/projectname")" .
+    name="$("$ROOT/script/projectname")"
+    timeout 300 docker build -t "$name" -f Dockerfile .
+    timeout 300 docker build -t "$name-server" -f Dockerfile.backend .
 }
 
 main "$@"

script/fmt

@@ -1,12 +1,14 @@
 #!/bin/sh
-# script/fmt: format all files (writes).
+# script/fmt: format the whole repo (writes): prettier over everything
+# it understands, then gofmt over the Go backend.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    yarn prettier --write .
+    "$ROOT/script/frontend-fmt"
+    "$ROOT/backend/script/fmt"
 }
 
 main "$@"

script/fmt-check

@@ -1,13 +1,14 @@
 #!/bin/sh
-# script/fmt-check: check formatting (read-only). Same scope as
-# script/fmt, but fails instead of writing.
+# script/fmt-check: check formatting across the whole repo (read-only).
+# Same scope as script/fmt, but fails instead of writing.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    yarn prettier --check .
+    "$ROOT/script/frontend-fmt-check"
+    "$ROOT/backend/script/fmt-check"
 }
 
 main "$@"

script/frontend-check

@@ -0,0 +1,18 @@
+#!/bin/sh
+# script/frontend-check: run the frontend half of the checks only (test,
+# lint, fmt-check). This exists for the frontend Dockerfile, whose build
+# stage is a node image with no Go toolchain; the backend half is gated
+# by Dockerfile.backend. Everywhere else, use script/check, which covers
+# the whole repo. Must not modify any files.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    "$ROOT/script/frontend-test"
+    "$ROOT/script/frontend-lint"
+    "$ROOT/script/frontend-fmt-check"
+}
+
+main "$@"

script/frontend-fmt

@@ -0,0 +1,14 @@
+#!/bin/sh
+# script/frontend-fmt: format the frontend and every other file prettier
+# understands, repo-wide (writes). backend/ is in .prettierignore; Go
+# sources are formatted by backend/script/fmt.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    yarn prettier --write .
+}
+
+main "$@"

script/frontend-fmt-check

@@ -0,0 +1,13 @@
+#!/bin/sh
+# script/frontend-fmt-check: check prettier formatting (read-only). Same
+# scope as script/frontend-fmt, but fails instead of writing.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    yarn prettier --check .
+}
+
+main "$@"

script/frontend-lint

@@ -0,0 +1,12 @@
+#!/bin/sh
+# script/frontend-lint: run the frontend linter (prettier in check mode).
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    yarn prettier --check .
+}
+
+main "$@"

script/frontend-test

@@ -0,0 +1,14 @@
+#!/bin/sh
+# script/frontend-test: run the frontend test suite. The frontend has no
+# unit tests; the production build serves as the test (fails on broken
+# code).
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    timeout 30 yarn build
+}
+
+main "$@"

script/frontend-viewport-test

@@ -1,102 +0,0 @@
-#!/bin/sh
-# script/frontend-viewport-test: verify the responsive layout of the built
-# frontend in a real browser engine.
-#
-# Builds dist/, serves it with the same nginx image and the same nginx.conf
-# the shipping container uses, points a containerised headless Chrome at it
-# over CDP, and asserts on computed layout at every viewport width derived
-# from the app's own CSS. See test/viewport/README.md for what this covers
-# and what it cannot.
-#
-# Deliberately not part of script/check: it needs Docker and takes far
-# longer than the 20s budget make test has to stay inside.
-set -eu
-
-ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
-
-# chromedp/headless-shell 151.0.7922.109, 2026-08-09
-BROWSER_IMAGE="chromedp/headless-shell@sha256:2d349b544a1ea6b5b5fd7c0fe99215ff662339c57407ee2e8c0a11af93516b04"
-# nginx:stable-alpine, 2026-02-22 (the digest Dockerfile ships)
-SERVER_IMAGE="nginx@sha256:15e96e59aa3b0aada3a121296e3bce117721f42d88f5f64217ef4b18f458c6ab"
-# node:22-alpine, 2026-02-22 (the digest Dockerfile builds with)
-NODE_IMAGE="node@sha256:e4bf2a82ad0a4037d28035ae71529873c069b13eb0455466ae0bc13363826e34"
-
-RUN_ID="$$-$(date +%s)"
-NETWORK="netwatch-viewport-$RUN_ID"
-SERVER="netwatch-viewport-server-$RUN_ID"
-BROWSER="netwatch-viewport-browser-$RUN_ID"
-HARNESS="netwatch-viewport-harness-$RUN_ID"
-ARTIFACT_DIR="$ROOT/tmp/viewport"
-
-# Every container is named and removed here, including the harness itself:
-# `timeout` below kills the `docker run` client, not the container it
-# started, and an unnamed survivor keeps the --internal network in use so
-# `docker network rm` fails too. This host runs many sessions at once and
-# neither may be left behind.
-cleanup() {
-    docker rm -f "$HARNESS" > /dev/null 2>&1 || true
-    docker rm -f "$BROWSER" > /dev/null 2>&1 || true
-    docker rm -f "$SERVER" > /dev/null 2>&1 || true
-    docker network rm "$NETWORK" > /dev/null 2>&1 || true
-}
-trap cleanup EXIT INT TERM
-
-main() {
-    cd "$ROOT"
-
-    # Test what ships: the production build, not a dev server.
-    "$ROOT/script/test"
-    if [ ! -f "$ROOT/dist/index.html" ]; then
-        echo "frontend-viewport-test: dist/index.html missing after build" >&2
-        exit 1
-    fi
-
-    mkdir -p "$ARTIFACT_DIR"
-
-    # An --internal network has no route off the host, so the browser
-    # cannot reach the real internet no matter what the page asks for.
-    # Latency probes are answered by the harness instead. This also means
-    # no port can be published from it, which is why the harness itself
-    # runs as a third container on the same network rather than on the
-    # host.
-    docker network create --internal "$NETWORK" > /dev/null
-
-    docker run -d --rm --name "$SERVER" \
-        --network "$NETWORK" --network-alias netwatch \
-        -v "$ROOT/dist:/usr/share/nginx/html:ro" \
-        -v "$ROOT/nginx.conf:/etc/nginx/conf.d/default.conf:ro" \
-        "$SERVER_IMAGE" > /dev/null
-
-    # The image's own entrypoint already exposes CDP on 9222 and passes
-    # --no-sandbox, so only extra flags belong here; re-specifying the
-    # debugging port collides with it and leaves the endpoint bound to
-    # loopback only. --hide-scrollbars keeps innerWidth equal to
-    # clientWidth, so the overflow assertion has no scrollbar-sized slack
-    # to hide behind, and matches the overlay scrollbars phones use.
-    docker run -d --rm --name "$BROWSER" --init --shm-size=1g \
-        --network "$NETWORK" \
-        "$BROWSER_IMAGE" \
-        --hide-scrollbars \
-        > /dev/null
-
-    # Chrome refuses DevTools requests whose Host header is neither
-    # localhost nor an IP address, so dial the container by address rather
-    # than by its network alias.
-    browser_ip="$(docker inspect \
-        -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' \
-        "$BROWSER")"
-
-    timeout 900 docker run --rm --init --name "$HARNESS" \
-        --network "$NETWORK" \
-        --user "$(id -u):$(id -g)" \
-        -v "$ROOT:/app" \
-        -w /app \
-        -e NETWATCH_ROOT=/app \
-        -e NETWATCH_BASE_URL=http://netwatch:8080 \
-        -e "NETWATCH_CDP_URL=http://$browser_ip:9222" \
-        -e NETWATCH_ARTIFACT_DIR=/app/tmp/viewport \
-        "$NODE_IMAGE" \
-        node test/viewport/harness.js
-}
-
-main "$@"

script/lint

@@ -1,12 +1,14 @@
 #!/bin/sh
-# script/lint: run the linter (prettier in check mode).
+# script/lint: lint the whole repo: prettier over everything it
+# understands, then golangci-lint over the Go backend.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    yarn prettier --check .
+    "$ROOT/script/frontend-lint"
+    "$ROOT/backend/script/lint"
 }
 
 main "$@"

script/precommit

@@ -3,10 +3,11 @@
 # checks fail. Our own extension to scripts-to-rule-them-all.
 set -eu
 
-SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
-    "$SCRIPT_DIR/check"
+    cd "$ROOT"
+    "$ROOT/script/check"
 }
 
 main "$@"

script/setup

@@ -3,11 +3,12 @@
 # installs dependencies and the git pre-commit hook.
 set -eu
 
-SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
-    "$SCRIPT_DIR/bootstrap"
-    "$SCRIPT_DIR/install-precommit"
+    cd "$ROOT"
+    "$ROOT/script/bootstrap"
+    "$ROOT/script/install-precommit"
 }
 
 main "$@"

script/test

@@ -1,13 +1,14 @@
 #!/bin/sh
-# script/test: run the test suite. This repo has no unit tests; the
-# production build serves as the test (fails on broken code).
+# script/test: run the test suite for the whole repo: the frontend at
+# the repo root, then the Go backend in backend/.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    timeout 30 yarn build
+    "$ROOT/script/frontend-test"
+    "$ROOT/backend/script/test"
 }
 
 main "$@"

test/viewport/README.md

@@ -1,112 +0,0 @@
-# Responsive-layout harness
-
-Automated verification of the responsive layout that landed in #5. Run it with:
-
-```bash
-make frontend-viewport-test
-```
-
-It builds `dist/`, serves it from the same digest-pinned `nginx` image and the
-same `nginx.conf` the shipping container uses, drives a digest-pinned headless
-Chrome against it over CDP, and asserts on computed layout at every viewport
-width derived from the app's own CSS. Screenshots land in `tmp/viewport/`
-alongside a `results.json`; they are artifacts for a human to look at when
-something fails, not the evidence. The assertions are the evidence.
-
-The target is deliberately outside `make check`: it needs Docker and takes
-minutes, and `make test` has to stay under 20 seconds.
-
-## How the widths are chosen
-
-Not from a list of phone models. `viewports.js` parses the `@media` conditions
-out of `src/styles.css` and scans `src/main.js` and `index.html` for Tailwind
-responsive prefixes, then tests every breakpoint it finds at one pixel below it,
-exactly on it, and one pixel above it. A generic 375px "phone" test sails
-straight past an off-by-one at a media query boundary; `max-width: 768px`
-matches _at_ 768, and the sweep pins down which side of that line each layout is
-on.
-
-Nothing hardcodes 768. Add a second media block or start using `md:` classes and
-the new breakpoint is covered without this directory being touched. The app is
-desktop-first today (all narrow rules live in `max-width` blocks); a
-`min-width`-only, mobile-first set is handled as its inverse, and a set that
-mixes the two makes the run fail loudly rather than test the right widths with
-the wrong expectation. Four further viewports are fixed anchors, each with a
-stated reason: a 320px floor, a 1280px desktop baseline, and two phone-landscape
-sizes straddling the breakpoint for the rotation case.
-
-## What it asserts
-
-- **app-rendered** — enough host rows exist and enough of them show a numeric
-  latency. This one exists so the rest cannot pass vacuously against a blank
-  page.
-- **no-horizontal-overflow** — `documentElement.scrollWidth` fits the layout
-  viewport, with the widest offending element named.
-- **nothing-past-viewport-edge** — no visible element's box extends past the
-  viewport edge.
-- **no-clipped-text** — nothing hides text behind `overflow: hidden`. Deliberate
-  ellipsis truncation (Tailwind's `truncate`, used on host names and URLs) is
-  excluded: it is a design choice, not breakage.
-- **tap-targets-44px** — every interactive control is at least 44x44 CSS px on
-  touch viewports, _and_ each selector in the control list matched at least the
-  number of visible elements it declares. The second half is what stops the
-  check passing vacuously: with size alone, a renamed class would take its
-  controls out of the measured set and the check would report "all 0 controls
-  are at least 44x44" and pass. See below.
-- **host-rows-stacked / host-rows-side-by-side** — the rows genuinely reflow.
-  Computed `flex-direction` _and_ the actual geometry are checked, and in the
-  narrow layout the info block and the sparkline must each occupy essentially
-  the full row width. A row that merely shrank its 420px column would fail.
-- **probing-still-runs / gateway-detection-still-runs** — narrow viewports keep
-  probing and keep detecting the gateway. The mobile early-return path proposed
-  in #8 was rejected; this is what would catch it coming back.
-
-### The tap-target threshold
-
-44x44 CSS px. That is the figure in Apple's Human Interface Guidelines and in
-WCAG 2.2 SC 2.5.5 "Target Size (Enhanced)". WCAG 2.2 SC 2.5.8 (level AA) sets a
-lower 24x24 floor, but that floor comes with a spacing exception these controls
-do not qualify for — the pin buttons sit directly against the host name they
-belong to.
-
-## Determinism
-
-The browser container runs on an `--internal` docker network and has no route to
-the internet, so the app's latency probes cannot reach anything real. The
-harness answers them itself from a fixed delay table, with a deterministic
-fraction failed outright, so the rows render a realistic spread of one-, two-
-and three-digit latencies plus some unreachable rows. That spread is what the
-layout has to survive; 24 identical `---` placeholders would not exercise it.
-
-## What this cannot verify
-
-Real limits, so nobody re-parks this issue as needing hardware:
-
-- **Non-Chromium engines.** This is Chrome. iOS Safari is WebKit and cannot be
-  emulated by it; Safari-specific bugs (viewport units under a collapsing URL
-  bar, `-webkit-fill-available`, form control metrics) will not show up here.
-- **Real touch input.** `hasTouch` emulation changes what the page is told, not
-  how a finger behaves. Gesture handling, scroll momentum, double-tap zoom and
-  hover-state fallbacks on touch are out of scope.
-- **Physical pixel density and rendering.** `deviceScaleFactor` is set, but
-  subpixel antialiasing, OLED colour rendering and actual legibility at a given
-  physical size are not measurable here.
-- **Fonts.** The container has DejaVu, not the platform's own UI monospace. Text
-  metrics are therefore close to, but not identical to, a real device — a layout
-  that fits here by a few pixels might not there.
-- **On-device performance.** Canvas sparkline redraw cost, battery, and
-  behaviour on a slow radio are not measured.
-- **Browser chrome.** The address bar, safe-area insets and notch cutouts are
-  not simulated.
-
-Everything else this issue was actually about — does the layout reflow, does
-anything overflow, is content clipped, are the controls big enough — is a
-function of viewport width and CSS, and is covered above.
-
-## Relation to the unit test framework (#21)
-
-Complementary layers, not two stacks. `vitest` (#21) will exercise module-level
-logic in-process with no browser. This harness exercises rendered layout in a
-real engine and is the only thing here that can see a media query. Neither
-replaces the other; assertions about computed styles and element geometry belong
-here, assertions about functions belong in `vitest`.

test/viewport/checks.js

@@ -1,245 +0,0 @@
-// Pass/fail decisions for the responsive-layout harness.
-//
-// Kept in node rather than in the page so that a failure can be reported
-// with the measurements that produced it. Every check runs at every
-// viewport; none of them short-circuits, so one failure does not hide the
-// rest.
-
-// Minimum tap target, in CSS pixels. 44x44 is the figure in Apple's Human
-// Interface Guidelines and in WCAG 2.2 SC 2.5.5 "Target Size (Enhanced)".
-// WCAG 2.2 SC 2.5.8 (level AA) sets a lower 24x24 floor, but that floor
-// comes with a spacing exception these controls do not qualify for: the
-// pin buttons sit directly against the host name they belong to. Held at
-// 44 deliberately.
-export const MIN_TAP_TARGET_PX = 44;
-
-// The controls named in the definition of done, plus the pause button.
-// Each carries the smallest number of *visible* instances the page has to
-// contain for the tap-target oracle to be measuring anything at all.
-//
-// Without those floors the check is inert: `undersized` is empty both when
-// every control is large enough and when the selectors have gone stale and
-// matched nothing, and the pass condition cannot tell those apart. A single
-// combined floor would not be enough either — 26 pin buttons would cover
-// for all three singleton controls vanishing at once — so the floor is per
-// selector, and one stale selector out of four fails the check.
-export const INTERACTIVE_CONTROLS = [
-    { selector: "#pause-btn", minCount: 1 },
-    { selector: "#interval-select", minCount: 1 },
-    // One per pinnable host row. `app-rendered` already requires at least
-    // 10 host rows, so a count below that means the pin buttons stopped
-    // being rendered per row rather than that there were fewer hosts.
-    { selector: ".pin-btn", minCount: 10 },
-    { selector: "#debug-toggle", minCount: 1 },
-];
-
-export const INTERACTIVE_SELECTORS = INTERACTIVE_CONTROLS.map(
-    (control) => control.selector,
-);
-
-// A host row is only "reflowed" if it stacked *and* went full width.
-// A row that merely shrank its 420px info column would keep
-// flex-direction: row, and a row that stacked but left the info column at
-// its fixed width would fail the width test.
-const FULL_WIDTH_FRACTION = 0.9;
-
-function summarise(items, format, limit = 3) {
-    const shown = items.slice(0, limit).map(format).join("; ");
-    const rest = items.length > limit ? ` (+${items.length - limit} more)` : "";
-    return shown + rest;
-}
-
-// Collapse an overflow report to the elements actually responsible.
-// Identical elements (24 host rows all doing the same thing) are counted
-// rather than listed, and the deepest ones come first, since every
-// ancestor of an overflowing element also reports as overflowing.
-function deepestOffenders(entries) {
-    const byElement = new Map();
-    for (const entry of entries) {
-        const reach = entry.reach ?? entry.right;
-        const existing = byElement.get(entry.el);
-        if (existing) {
-            existing.count += 1;
-            existing.reach = Math.max(existing.reach, reach);
-        } else {
-            byElement.set(entry.el, { ...entry, reach, count: 1 });
-        }
-    }
-    return [...byElement.values()].sort(
-        (a, b) => b.depth - a.depth || b.reach - a.reach,
-    );
-}
-
-function checkRowLayout(row, expectStacked) {
-    if (expectStacked) {
-        if (row.flexDirection !== "column") {
-            return `row ${row.index}: flex-direction is ${row.flexDirection}, expected column`;
-        }
-        if (row.sparkline.top < row.info.bottom - 1) {
-            return `row ${row.index}: sparkline top ${row.sparkline.top} is above info bottom ${row.info.bottom} — still side by side`;
-        }
-        const minWidth = row.containerWidth * FULL_WIDTH_FRACTION;
-        if (row.info.width < minWidth) {
-            return `row ${row.index}: info block is ${row.info.width}px of ${row.containerWidth}px — shrunk, not reflowed`;
-        }
-        if (row.sparkline.width < minWidth) {
-            return `row ${row.index}: sparkline is ${row.sparkline.width}px of ${row.containerWidth}px — shrunk, not reflowed`;
-        }
-        return null;
-    }
-
-    if (row.flexDirection !== "row") {
-        return `row ${row.index}: flex-direction is ${row.flexDirection}, expected row`;
-    }
-    if (row.sparkline.left < row.info.right - 1) {
-        return `row ${row.index}: sparkline left ${row.sparkline.left} overlaps info right ${row.info.right} — not side by side`;
-    }
-    return null;
-}
-
-export function evaluateChecks(facts, viewport, probes) {
-    const checks = [];
-    const check = (name, ok, detail) => checks.push({ name, ok, detail });
-
-    // Guard against the whole harness passing vacuously because the page
-    // never rendered. Everything below is only meaningful if this holds.
-    check(
-        "app-rendered",
-        facts.rowCount >= 10 && facts.numericLatencies >= 5,
-        `${facts.rowCount} host rows, ${facts.numericLatencies} showing a numeric latency`,
-    );
-
-    const viewportWidth = Math.min(facts.innerWidth, facts.documentClientWidth);
-    const culprits = deepestOffenders([
-        ...facts.overflowing,
-        ...facts.contentOverflowing,
-    ]);
-    check(
-        "no-horizontal-overflow",
-        facts.documentScrollWidth <= viewportWidth,
-        `documentElement.scrollWidth ${facts.documentScrollWidth} vs viewport ${viewportWidth}` +
-            (culprits.length === 0
-                ? ""
-                : "; widest content: " +
-                  summarise(
-                      culprits,
-                      (c) =>
-                          `${c.el} reaches ${Math.round(c.reach)}px${c.count > 1 ? ` (x${c.count})` : ""}`,
-                  )),
-    );
-
-    check(
-        "nothing-past-viewport-edge",
-        facts.overflowing.length === 0,
-        facts.overflowing.length === 0
-            ? "no element extends past the viewport"
-            : `${facts.overflowing.length} element(s) past the edge: ` +
-                  summarise(
-                      facts.overflowing,
-                      (o) => `${o.el} spans ${o.left}..${o.right}`,
-                  ),
-    );
-
-    check(
-        "no-clipped-text",
-        facts.clipped.length === 0,
-        facts.clipped.length === 0
-            ? "no element hides text behind overflow (deliberate ellipsis excluded)"
-            : `${facts.clipped.length} element(s) clipping text: ` +
-                  summarise(
-                      facts.clipped,
-                      (c) =>
-                          `${c.el} scrollWidth ${c.scrollWidth} > clientWidth ${c.clientWidth}`,
-                  ),
-    );
-
-    if (viewport.touch) {
-        // Presence first: a selector that matches nothing contributes no
-        // undersized targets, so without this the check would report
-        // "all 0 controls are at least 44x44" and pass.
-        const seen = new Map();
-        for (const target of facts.tapTargets) {
-            seen.set(target.selector, (seen.get(target.selector) ?? 0) + 1);
-        }
-        const missing = INTERACTIVE_CONTROLS.filter(
-            (control) => (seen.get(control.selector) ?? 0) < control.minCount,
-        );
-
-        const undersized = facts.tapTargets.filter(
-            (t) => t.width < MIN_TAP_TARGET_PX || t.height < MIN_TAP_TARGET_PX,
-        );
-        const bySelector = new Map();
-        for (const target of undersized) {
-            const existing = bySelector.get(target.selector);
-            if (!existing || target.width * target.height < existing.area) {
-                bySelector.set(target.selector, {
-                    ...target,
-                    area: target.width * target.height,
-                    count: (existing?.count ?? 0) + 1,
-                });
-            } else {
-                existing.count += 1;
-            }
-        }
-        const detail = [];
-        if (missing.length > 0) {
-            detail.push(
-                "oracle is not measuring the page: " +
-                    summarise(
-                        missing,
-                        (c) =>
-                            `${c.selector} matched ${seen.get(c.selector) ?? 0} visible element(s), expected at least ${c.minCount}`,
-                        4,
-                    ),
-            );
-        }
-        detail.push(
-            undersized.length === 0
-                ? `${facts.tapTargets.length} controls measured, all at least ${MIN_TAP_TARGET_PX}x${MIN_TAP_TARGET_PX}`
-                : `${undersized.length} of ${facts.tapTargets.length} controls below ${MIN_TAP_TARGET_PX}x${MIN_TAP_TARGET_PX}: ` +
-                      summarise(
-                          [...bySelector.values()],
-                          (t) =>
-                              `${t.selector} ${t.width}x${t.height}${t.count > 1 ? ` (x${t.count})` : ""}`,
-                          4,
-                      ),
-        );
-        check(
-            `tap-targets-${MIN_TAP_TARGET_PX}px`,
-            missing.length === 0 && undersized.length === 0,
-            detail.join("; "),
-        );
-    }
-
-    const badRows = facts.rows
-        .map((row) => checkRowLayout(row, viewport.expectStacked))
-        .filter(Boolean);
-    check(
-        viewport.expectStacked ? "host-rows-stacked" : "host-rows-side-by-side",
-        facts.rows.length > 0 && badRows.length === 0,
-        facts.rows.length === 0
-            ? "no host rows were measured"
-            : badRows.length === 0
-              ? `all ${facts.rows.length} rows laid out as expected`
-              : `${badRows.length} of ${facts.rows.length} rows wrong: ` +
-                summarise(badRows, (r) => r),
-    );
-
-    // The mobile early-return path proposed in #8 was rejected: narrow
-    // viewports must keep probing and keep detecting the gateway, not
-    // quietly skip work.
-    check(
-        "probing-still-runs",
-        probes.attempted > 0,
-        `${probes.attempted} outbound probe requests issued`,
-    );
-    check(
-        "gateway-detection-still-runs",
-        facts.gatewayDetected,
-        facts.gatewayDetected
-            ? "Local Gateway row present"
-            : "no Local Gateway row — gateway detection did not run or did not complete",
-    );
-
-    return checks;
-}

test/viewport/facts.js

@@ -1,184 +0,0 @@
-// Layout facts collected from inside the page.
-//
-// This function is serialised and evaluated in the browser, so it must be
-// entirely self-contained: no imports, no closures over module scope. It
-// only *measures*; every pass/fail decision is made back in node by
-// checks.js, so failures can be reported with real numbers attached.
-
-export function collectLayoutFacts(options) {
-    const describe = (el) => {
-        const id = el.id ? "#" + el.id : "";
-        const classes =
-            typeof el.className === "string" && el.className.trim()
-                ? "." + el.className.trim().split(/\s+/).slice(0, 3).join(".")
-                : "";
-        return el.tagName.toLowerCase() + id + classes;
-    };
-
-    const round = (n) => Math.round(n * 10) / 10;
-
-    // Overflow propagates up every ancestor, so a single wide element
-    // reports as body, #app, the row, and so on. Depth lets the report
-    // name the deepest — that is, the actual — offender.
-    const depthOf = (el) => {
-        let depth = 0;
-        for (let node = el.parentElement; node; node = node.parentElement) {
-            depth++;
-        }
-        return depth;
-    };
-
-    const isVisible = (el) => {
-        const style = getComputedStyle(el);
-        if (style.display === "none") return false;
-        if (style.visibility === "hidden") return false;
-        const rect = el.getBoundingClientRect();
-        return rect.width > 0 && rect.height > 0;
-    };
-
-    const innerWidth = window.innerWidth;
-    const clientWidth = document.documentElement.clientWidth;
-    // Under mobile emulation Chrome lets window.innerWidth *grow* to the
-    // width of overflowing content, exactly as a phone zooms out to fit a
-    // too-wide page. Measuring against it would therefore hide the
-    // overflow it is supposed to expose: at a 320px device width a page
-    // that spills to 350 reports innerWidth 350 and looks clean. Every
-    // comparison below is against the layout viewport instead.
-    const viewportWidth = Math.min(innerWidth, clientWidth);
-    const elements = Array.from(document.querySelectorAll("body *"));
-
-    // Elements sticking out past the right (or left) edge of the viewport.
-    // The document-level scrollWidth check says *that* the page overflows;
-    // this says *what* is doing it.
-    const overflowing = [];
-    // Elements clipping their own text. Deliberate ellipsis truncation
-    // (Tailwind's `truncate`) is opt-in and excluded: it is a design
-    // choice, not breakage.
-    const clipped = [];
-    // Elements whose content spills out of their own box without being
-    // clipped, past the right edge of the viewport. A block element is
-    // only ever as wide as its container, so text overflowing it has no
-    // element rect of its own to catch — but it is exactly what drags
-    // documentElement.scrollWidth past the viewport width, so without
-    // this the page-level overflow failure has nothing to point at.
-    const contentOverflowing = [];
-
-    for (const el of elements) {
-        if (!isVisible(el)) continue;
-        const rect = el.getBoundingClientRect();
-        if (rect.right > viewportWidth + 1 || rect.left < -1) {
-            overflowing.push({
-                el: describe(el),
-                depth: depthOf(el),
-                left: round(rect.left),
-                right: round(rect.right),
-            });
-        }
-        const style = getComputedStyle(el);
-        const clips =
-            style.overflowX === "hidden" || style.overflowX === "clip";
-        const ellipsis = style.textOverflow === "ellipsis";
-        const hasText = el.textContent.trim().length > 0;
-        const spills =
-            el.clientWidth > 0 && el.scrollWidth > el.clientWidth + 1;
-        if (clips && !ellipsis && hasText && spills) {
-            clipped.push({
-                el: describe(el),
-                scrollWidth: el.scrollWidth,
-                clientWidth: el.clientWidth,
-            });
-        }
-        if (
-            !clips &&
-            spills &&
-            rect.left + el.scrollWidth > viewportWidth + 1
-        ) {
-            contentOverflowing.push({
-                el: describe(el),
-                depth: depthOf(el),
-                scrollWidth: el.scrollWidth,
-                clientWidth: el.clientWidth,
-                reach: round(rect.left + el.scrollWidth),
-            });
-        }
-    }
-
-    // Interactive controls. The measured target is the nearest thing that
-    // is genuinely tappable — for a checkbox that is the <label> wrapping
-    // it, which is larger than the box itself and is what a finger hits.
-    const tapTargets = [];
-    for (const selector of options.interactiveSelectors) {
-        for (const el of document.querySelectorAll(selector)) {
-            if (!isVisible(el)) continue;
-            const target = el.closest("button, a, label, select") || el;
-            const rect = target.getBoundingClientRect();
-            tapTargets.push({
-                selector,
-                el: describe(target),
-                width: round(rect.width),
-                height: round(rect.height),
-            });
-        }
-    }
-
-    // Host rows. The question is not "did it get narrower" but "did it
-    // reflow": the info block and the sparkline must end up stacked
-    // vertically and full width in the narrow layout, and side by side in
-    // the wide one. Both the computed flex-direction and the actual
-    // geometry are recorded so a row that claims to be a column but is
-    // still laid out side by side cannot slip through.
-    const rows = [];
-    for (const row of document.querySelectorAll(".host-row")) {
-        const inner = row.firstElementChild;
-        if (!inner) continue;
-        const sparkline = inner.querySelector(".sparkline-container");
-        const info = sparkline ? sparkline.previousElementSibling : null;
-        if (!sparkline || !info) continue;
-        const innerStyle = getComputedStyle(inner);
-        const innerRect = inner.getBoundingClientRect();
-        const infoRect = info.getBoundingClientRect();
-        const sparkRect = sparkline.getBoundingClientRect();
-        rows.push({
-            index: row.dataset.index,
-            flexDirection: innerStyle.flexDirection,
-            containerWidth: round(innerRect.width),
-            info: {
-                left: round(infoRect.left),
-                right: round(infoRect.right),
-                bottom: round(infoRect.bottom),
-                width: round(infoRect.width),
-            },
-            sparkline: {
-                left: round(sparkRect.left),
-                top: round(sparkRect.top),
-                width: round(sparkRect.width),
-            },
-        });
-    }
-
-    const localRows = Array.from(
-        document.querySelectorAll("#local-hosts .host-row"),
-    );
-
-    return {
-        innerWidth,
-        // innerWidth includes any classic scrollbar, clientWidth does not.
-        // Reported separately so the overflow check can hold itself to the
-        // narrower of the two rather than to whichever one is more
-        // forgiving.
-        documentClientWidth: document.documentElement.clientWidth,
-        documentScrollWidth: document.documentElement.scrollWidth,
-        overflowing,
-        contentOverflowing,
-        clipped,
-        tapTargets,
-        rows,
-        rowCount: document.querySelectorAll(".host-row").length,
-        numericLatencies: Array.from(
-            document.querySelectorAll(".latency-value"),
-        ).filter((el) => /\d/.test(el.textContent)).length,
-        gatewayDetected: localRows.some((row) =>
-            row.textContent.includes("Local Gateway"),
-        ),
-    };
-}

test/viewport/harness.js

@@ -1,258 +0,0 @@
-// Responsive-layout harness.
-//
-// Drives the built frontend in a real, containerised, digest-pinned Chrome
-// over CDP and asserts on computed layout at every viewport width derived
-// from the app's own CSS. Screenshots are written alongside as artifacts;
-// they are not the evidence, the assertions are.
-//
-// This is not meant to be run by hand. `make frontend-viewport-test` brings
-// up the browser and the web server and then runs this; every input it
-// needs arrives in the environment.
-
-import { mkdirSync, writeFileSync } from "node:fs";
-import { join } from "node:path";
-import puppeteer from "puppeteer-core";
-import { collectLayoutFacts } from "./facts.js";
-import { evaluateChecks, INTERACTIVE_SELECTORS } from "./checks.js";
-import { deriveViewports } from "./viewports.js";
-
-function required(name) {
-    const value = process.env[name];
-    if (!value) {
-        throw new Error(
-            `${name} is not set; run this via script/frontend-viewport-test`,
-        );
-    }
-    return value;
-}
-
-const ROOT = required("NETWATCH_ROOT");
-const BASE_URL = required("NETWATCH_BASE_URL");
-const CDP_URL = required("NETWATCH_CDP_URL");
-const ARTIFACT_DIR = required("NETWATCH_ARTIFACT_DIR");
-
-const BROWSER_TIMEOUT_MS = 60000;
-const PAGE_TIMEOUT_MS = 30000;
-
-// Canned responses for the app's outbound latency probes. The browser
-// container sits on an --internal docker network and physically cannot
-// reach the internet, so nothing here is about blocking traffic; it is
-// about determinism. Real probes would render 24 rows of whatever the
-// network happened to be doing. These delays make the rows show a
-// realistic spread of value widths — one, two and three digit latencies,
-// plus some unreachable rows — because that spread is what the layout has
-// to survive.
-const PROBE_DELAYS_MS = [2, 45, 123, 456, 780];
-// One in every UNREACHABLE_MODULUS probes is failed outright so that the
-// offline row rendering is exercised too.
-const UNREACHABLE_MODULUS = 7;
-// The gateway candidate that "answers", so gateway detection succeeds and
-// the Local Gateway row renders. Matches GATEWAY_CANDIDATES in src/main.js.
-const RESPONSIVE_GATEWAY = "http://192.168.1.1";
-
-const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
-
-function stableHash(text) {
-    let hash = 0;
-    for (let i = 0; i < text.length; i++) {
-        hash = (hash * 31 + text.charCodeAt(i)) | 0;
-    }
-    return Math.abs(hash);
-}
-
-async function connectBrowser() {
-    const deadline = Date.now() + BROWSER_TIMEOUT_MS;
-    let lastError;
-    for (;;) {
-        try {
-            const response = await fetch(`${CDP_URL}/json/version`);
-            const info = await response.json();
-            // The endpoint advertises whatever Host it was reached on;
-            // pin it back to the address we actually dialled.
-            const endpoint = new URL(info.webSocketDebuggerUrl);
-            endpoint.host = new URL(CDP_URL).host;
-            const browser = await puppeteer.connect({
-                browserWSEndpoint: endpoint.toString(),
-                protocolTimeout: BROWSER_TIMEOUT_MS,
-            });
-            return { browser, version: info.Browser };
-        } catch (error) {
-            lastError = error;
-            if (Date.now() > deadline) {
-                throw new Error(`browser never came up: ${lastError}`);
-            }
-            await sleep(250);
-        }
-    }
-}
-
-function installProbeResponder(page, probes) {
-    const respond = (request, delayMs) =>
-        sleep(delayMs).then(() =>
-            request.respond({
-                status: 200,
-                contentType: "text/plain",
-                body: "",
-            }),
-        );
-
-    page.on("request", (request) => {
-        const url = request.url();
-        const settle = async () => {
-            if (url.startsWith(BASE_URL) || url.startsWith("data:")) {
-                return request.continue();
-            }
-            probes.attempted++;
-            if (url.startsWith(RESPONSIVE_GATEWAY)) {
-                probes.fulfilled++;
-                return respond(request, 5);
-            }
-            const hash = stableHash(url);
-            if (hash % UNREACHABLE_MODULUS === 0) {
-                probes.failed++;
-                return request.abort("connectionfailed");
-            }
-            probes.fulfilled++;
-            return respond(
-                request,
-                PROBE_DELAYS_MS[hash % PROBE_DELAYS_MS.length],
-            );
-        };
-        // The page may be torn down while a delayed response is pending;
-        // that is not a harness failure.
-        settle().catch(() => {});
-    });
-}
-
-async function runViewport(browser, viewport) {
-    const page = await browser.newPage();
-    const probes = { attempted: 0, fulfilled: 0, failed: 0 };
-    try {
-        page.setDefaultTimeout(PAGE_TIMEOUT_MS);
-        await page.setRequestInterception(true);
-        installProbeResponder(page, probes);
-        await page.setViewport({
-            width: viewport.width,
-            height: viewport.height,
-            deviceScaleFactor: viewport.deviceScaleFactor,
-            isMobile: viewport.touch,
-            hasTouch: viewport.touch,
-            isLandscape: viewport.width > viewport.height,
-        });
-
-        await page.goto(BASE_URL, { waitUntil: "load" });
-        await page.waitForSelector(".host-row");
-
-        // The app discards its first tick as a cold start, so rows only
-        // carry real values from the second one. Changing the interval
-        // restarts the loop at 1s, which reaches a populated UI without
-        // waiting out two default 3s intervals — and exercises the
-        // interval dropdown while we are at it.
-        await page.select("#interval-select", "1000");
-        await page.waitForFunction(
-            () =>
-                Array.from(document.querySelectorAll(".latency-value")).filter(
-                    (el) => /\d/.test(el.textContent),
-                ).length >= 5,
-        );
-        // Let the resize/redraw handlers settle before measuring.
-        await page.evaluate(
-            () =>
-                new Promise((resolve) =>
-                    requestAnimationFrame(() => requestAnimationFrame(resolve)),
-                ),
-        );
-
-        const facts = await page.evaluate(collectLayoutFacts, {
-            interactiveSelectors: INTERACTIVE_SELECTORS,
-        });
-
-        const screenshot = join(
-            ARTIFACT_DIR,
-            `${viewport.width}x${viewport.height}-${viewport.name}.png`,
-        );
-        await page.screenshot({ path: screenshot, fullPage: true });
-
-        return {
-            viewport,
-            probes,
-            facts,
-            screenshot,
-            checks: evaluateChecks(facts, viewport, probes),
-        };
-    } finally {
-        await page.close().catch(() => {});
-    }
-}
-
-function report(results, conditions, browserVersion) {
-    const label = (viewport) =>
-        `${viewport.width}x${viewport.height}`.padEnd(9) +
-        " " +
-        viewport.name.padEnd(24);
-
-    console.log(`browser:     ${browserVersion}`);
-    console.log(`served from: ${BASE_URL} (built dist/)`);
-    console.log(
-        "breakpoints: " +
-            conditions
-                .map((c) => `${c.type}-width ${c.px}px (${c.source})`)
-                .join(", "),
-    );
-    console.log("");
-
-    let passed = 0;
-    let failed = 0;
-    for (const result of results) {
-        const bad = result.checks.filter((c) => !c.ok);
-        passed += result.checks.length - bad.length;
-        failed += bad.length;
-        // Passing viewports get one line. Detail is for failures.
-        console.log(
-            `${bad.length === 0 ? "PASS" : "FAIL"} ${label(result.viewport)} ` +
-                `${result.checks.length - bad.length}/${result.checks.length} checks` +
-                `${result.viewport.expectStacked ? "  [narrow layout expected]" : ""}`,
-        );
-        for (const check of bad) {
-            console.log(`       ${check.name}: ${check.detail}`);
-        }
-        if (bad.length > 0) {
-            console.log(`       why this width: ${result.viewport.why}`);
-            console.log(`       screenshot: ${result.screenshot}`);
-        }
-    }
-
-    console.log("");
-    console.log(
-        `${results.length} viewports, ${passed + failed} checks: ` +
-            `${passed} passed, ${failed} failed`,
-    );
-    console.log(`artifacts: ${ARTIFACT_DIR}`);
-    return failed;
-}
-
-async function main() {
-    const { conditions, viewports } = deriveViewports(ROOT);
-    mkdirSync(ARTIFACT_DIR, { recursive: true });
-
-    const { browser, version } = await connectBrowser();
-    const results = [];
-    try {
-        for (const viewport of viewports) {
-            results.push(await runViewport(browser, viewport));
-        }
-    } finally {
-        await browser.disconnect().catch(() => {});
-    }
-
-    writeFileSync(
-        join(ARTIFACT_DIR, "results.json"),
-        JSON.stringify({ browser: version, conditions, results }, null, 2) +
-            "\n",
-    );
-
-    const failed = report(results, conditions, version);
-    process.exitCode = failed === 0 ? 0 : 1;
-}
-
-await main();

test/viewport/viewports.js

@@ -1,224 +0,0 @@
-// Viewport derivation for the responsive-layout harness.
-//
-// The widths tested are read out of the CSS the application actually
-// ships, not taken from a list of popular phone models. A generic 375px
-// "phone" test sails straight past an off-by-one error at a media query
-// boundary, which is the classic way a responsive layout breaks, so
-// every breakpoint found in the sources is probed three times: one pixel
-// below it, exactly on it, and one pixel above it.
-//
-// Nothing here hardcodes 768. If someone adds a second media block or
-// starts using Tailwind responsive prefixes, that breakpoint starts
-// being covered without this file being edited.
-
-import { readFileSync } from "node:fs";
-import { join } from "node:path";
-
-// Tailwind CSS v4 default breakpoints, in rem. The app currently uses
-// none of these prefixes, so the whole table is inert until someone
-// writes an `md:`-prefixed utility class.
-const TAILWIND_BREAKPOINT_REM = {
-    sm: 40,
-    md: 48,
-    lg: 64,
-    xl: 80,
-    "2xl": 96,
-};
-
-// The app does not override the root font size, so rem and em in media
-// queries resolve against the browser default.
-const ROOT_FONT_SIZE_PX = 16;
-
-// Extract every min-width / max-width condition from the @media blocks in
-// a stylesheet. Returns e.g. [{ type: "max", px: 768, source: "..." }].
-export function mediaConditionsFromCss(css, source) {
-    const conditions = [];
-    for (const block of css.matchAll(/@media([^{]+)\{/g)) {
-        const features = block[1].matchAll(
-            /\(\s*(min|max)-width\s*:\s*([\d.]+)(px|rem|em)\s*\)/g,
-        );
-        for (const feature of features) {
-            const scale = feature[3] === "px" ? 1 : ROOT_FONT_SIZE_PX;
-            conditions.push({
-                type: feature[1],
-                px: Math.round(Number(feature[2]) * scale),
-                source,
-            });
-        }
-    }
-    return conditions;
-}
-
-// Extract the breakpoints implied by Tailwind responsive prefixes used in
-// markup. A prefix only counts when it opens a utility class, so `text-sm`
-// does not masquerade as the `sm:` breakpoint.
-export function mediaConditionsFromMarkup(sources) {
-    const conditions = [];
-    for (const { path, text } of sources) {
-        for (const [name, rem] of Object.entries(TAILWIND_BREAKPOINT_REM)) {
-            const used = new RegExp(
-                `(^|["'\\s])${name}:[a-z0-9[\\](),_./%-]+`,
-                "m",
-            ).test(text);
-            if (used) {
-                conditions.push({
-                    type: "min",
-                    px: rem * ROOT_FONT_SIZE_PX,
-                    source: path,
-                });
-            }
-        }
-    }
-    return conditions;
-}
-
-// Whether a given width should be rendering the app's narrow (stacked)
-// layout.
-//
-// Two breakpoint styles can be answered from the condition list alone:
-//
-//   - Desktop-first, which is what the app ships today: the wide layout is
-//     unconditional and every narrow rule lives in a `max-width` block, so
-//     a width is narrow exactly when one of those blocks matches. Note that
-//     `max-width: 768px` matches *at* 768 — getting this inclusive boundary
-//     wrong in either direction is what the three-widths-per-breakpoint
-//     sweep exists to catch.
-//   - Mobile-first, which is what Tailwind's `sm:`/`md:` prefixes are: the
-//     stacked layout is the unconditional base and a `min-width` block is
-//     what widens it, so a width is narrow exactly when it sits below every
-//     `min-width` breakpoint.
-//
-// A mix of the two cannot be resolved from the breakpoints alone — which
-// block owns the host-row reflow is a property of the rules inside it, not
-// of the condition — so this throws rather than guessing. Guessing is how
-// the wrong expectation gets applied at the right widths and the whole
-// sweep quietly verifies nothing.
-export function expectsStackedLayout(width, conditions) {
-    const kinds = new Set(conditions.map((c) => c.type));
-    for (const kind of kinds) {
-        if (kind !== "max" && kind !== "min") {
-            throw new Error(
-                `unsupported media condition type "${kind}" in ` +
-                    "expectsStackedLayout (test/viewport/viewports.js)",
-            );
-        }
-    }
-    if (kinds.has("max") && kinds.has("min")) {
-        throw new Error(
-            "the app now mixes max-width and min-width breakpoints (" +
-                conditions
-                    .map((c) => `${c.type}-width ${c.px}px in ${c.source}`)
-                    .join(", ") +
-                "), so which layout a width should be showing can no longer " +
-                "be inferred from the breakpoint list; teach " +
-                "expectsStackedLayout in test/viewport/viewports.js which " +
-                "block owns the host-row reflow",
-        );
-    }
-    if (kinds.has("min")) {
-        return !conditions.some((c) => width >= c.px);
-    }
-    return conditions.some((c) => width <= c.px);
-}
-
-// Viewports that are not derived from a breakpoint. Each one is here for
-// a stated reason; none of them is a stand-in for "a phone".
-const ANCHOR_VIEWPORTS = [
-    {
-        name: "floor-portrait",
-        width: 320,
-        height: 568,
-        deviceScaleFactor: 2,
-        touch: true,
-        why: "320px is the narrowest viewport still in mainstream use; nothing has to work below it",
-    },
-    {
-        name: "phone-landscape-narrow",
-        width: 667,
-        height: 375,
-        deviceScaleFactor: 2,
-        touch: true,
-        why: "phone rotated to landscape, still inside the narrow layout",
-    },
-    {
-        name: "phone-landscape-wide",
-        width: 844,
-        height: 390,
-        deviceScaleFactor: 3,
-        touch: true,
-        why: "large phone rotated to landscape: crosses into the wide layout while still being a touch device",
-    },
-    {
-        name: "desktop",
-        width: 1280,
-        height: 800,
-        deviceScaleFactor: 1,
-        touch: false,
-        why: "desktop baseline",
-    },
-];
-
-export function deriveViewports(root) {
-    const conditions = [
-        ...mediaConditionsFromCss(
-            readFileSync(join(root, "src/styles.css"), "utf8"),
-            "src/styles.css",
-        ),
-        ...mediaConditionsFromMarkup([
-            {
-                path: "src/main.js",
-                text: readFileSync(join(root, "src/main.js"), "utf8"),
-            },
-            {
-                path: "index.html",
-                text: readFileSync(join(root, "index.html"), "utf8"),
-            },
-        ]),
-    ];
-
-    if (conditions.length === 0) {
-        throw new Error(
-            "no responsive breakpoints found in src/styles.css, src/main.js or " +
-                "index.html — either the responsive layout was deleted or this " +
-                "derivation has stopped matching the sources",
-        );
-    }
-
-    const viewports = new Map();
-    const add = (viewport) => {
-        const key = `${viewport.width}x${viewport.height}`;
-        if (!viewports.has(key)) viewports.set(key, viewport);
-    };
-
-    for (const condition of conditions) {
-        for (const [offset, label] of [
-            [-1, "below"],
-            [0, "at"],
-            [+1, "above"],
-        ]) {
-            const width = condition.px + offset;
-            add({
-                name: `${condition.type}-width-${condition.px}-${label}`,
-                width,
-                // Tall enough that the whole app is laid out in one column
-                // without the viewport height influencing wrapping.
-                height: 1024,
-                deviceScaleFactor: 2,
-                touch: true,
-                why: `${offset === 0 ? "exactly on" : `1px ${label}`} the ${condition.type}-width: ${condition.px}px breakpoint declared in ${condition.source}`,
-            });
-        }
-    }
-
-    for (const anchor of ANCHOR_VIEWPORTS) add(anchor);
-
-    return {
-        conditions,
-        viewports: [...viewports.values()]
-            .map((viewport) => ({
-                ...viewport,
-                expectStacked: expectsStackedLayout(viewport.width, conditions),
-            }))
-            .sort((a, b) => a.width - b.width || a.height - b.height),
-    };
-}

yarn.lock

@@ -197,14 +197,6 @@
     "@emnapi/runtime" "^1.7.1"
     "@tybys/wasm-util" "^0.10.1"
 
-"@puppeteer/browsers@3.1.0":
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/@puppeteer/browsers/-/browsers-3.1.0.tgz#5728ae0bc649263133ac1f8bd5d360eb75d11748"
-  integrity sha512-RDLpio3fH/qrj5k4DVY6eyiN8tCS0Zovd/6jW//n605oeqkWcUjn+3k+9ZtZBnbwMpsu0F7xDIiKXvVmG5c5Bw==
-  dependencies:
-    modern-tar "^0.7.6"
-    yargs "^18.0.0"
-
 "@rollup/rollup-android-arm-eabi@4.57.0":
   version "4.57.0"
   resolved "https://registry.yarnpkg.com/@rollup/rollup-android-arm-eabi/-/rollup-android-arm-eabi-4.57.0.tgz#f762035679a6b168138c94c960fda0b0cdb00d98"
@@ -449,16 +441,6 @@
   resolved "https://registry.yarnpkg.com/@types/estree/-/estree-1.0.8.tgz#958b91c991b1867ced318bedea0e215ee050726e"
   integrity sha512-dWHzHa2WqEXI/O1E9OjrocMTKJl2mSrEolh1Iomrv6U+JuNwaHXsXx9bLu5gG7BUWFIN0skIQJQ/L1rIex4X6w==
 
-ansi-regex@^6.2.2:
-  version "6.2.2"
-  resolved "https://registry.yarnpkg.com/ansi-regex/-/ansi-regex-6.2.2.tgz#60216eea464d864597ce2832000738a0589650c1"
-  integrity sha512-Bq3SmSpyFHaWjPk8If9yc6svM8c56dB5BAtW4Qbw5jHTwwXXcTLoRMkpDJp6VL0XzlWaCHTXrkFURMYmD0sLqg==
-
-ansi-styles@^6.2.1:
-  version "6.2.3"
-  resolved "https://registry.yarnpkg.com/ansi-styles/-/ansi-styles-6.2.3.tgz#c044d5dcc521a076413472597a1acb1f103c4041"
-  integrity sha512-4Dj6M28JB+oAH8kFkTLUo+a2jwOFkuqb3yucU0CANcRRUbxS0cP0nZYCGjcc3BNXwRIsUVmDGgzawme7zvJHvg==
-
 autoprefixer@^10.4.23:
   version "10.4.23"
   resolved "https://registry.yarnpkg.com/autoprefixer/-/autoprefixer-10.4.23.tgz#c6aa6db8e7376fcd900f9fd79d143ceebad8c4e6"
@@ -491,43 +473,16 @@ caniuse-lite@^1.0.30001759, caniuse-lite@^1.0.30001760:
   resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30001766.tgz#b6f6b55cb25a2d888d9393104d14751c6a7d6f7a"
   integrity sha512-4C0lfJ0/YPjJQHagaE9x2Elb69CIqEPZeG0anQt9SIvIoOH4a4uaRl73IavyO+0qZh6MDLH//DrXThEYKHkmYA==
 
-chromium-bidi@17.0.2:
-  version "17.0.2"
-  resolved "https://registry.yarnpkg.com/chromium-bidi/-/chromium-bidi-17.0.2.tgz#921a586deecd0c2d8b9242c4c1b73c3aa39ff77c"
-  integrity sha512-5v9GQFhTktFvotn/OFNJBmKLKRAb6n9r0bVCwf7sHgWc3/JryK0bj1nn93L3pHFrfgcsu6Be6EWsDi+1XHTGDg==
-  dependencies:
-    mitt "^3.0.1"
-    zod "^3.24.1"
-
-cliui@^9.0.1:
-  version "9.0.1"
-  resolved "https://registry.yarnpkg.com/cliui/-/cliui-9.0.1.tgz#6f7890f386f6f1f79953adc1f78dec46fcc2d291"
-  integrity sha512-k7ndgKhwoQveBL+/1tqGJYNz097I7WOvwbmmU2AR5+magtbjPWQTS1C5vzGkBC8Ym8UWRzfKUzUUqFLypY4Q+w==
-  dependencies:
-    string-width "^7.2.0"
-    strip-ansi "^7.1.0"
-    wrap-ansi "^9.0.0"
-
 detect-libc@^2.0.3:
   version "2.1.2"
   resolved "https://registry.yarnpkg.com/detect-libc/-/detect-libc-2.1.2.tgz#689c5dcdc1900ef5583a4cb9f6d7b473742074ad"
   integrity sha512-Btj2BOOO83o3WyH59e8MgXsxEQVcarkUOpEYrubB0urwnN10yQ364rsiByU11nZlqWYZm05i/of7io4mzihBtQ==
 
-devtools-protocol@0.0.1653615:
-  version "0.0.1653615"
-  resolved "https://registry.yarnpkg.com/devtools-protocol/-/devtools-protocol-0.0.1653615.tgz#c600e0c619612156b2422a66d958ba188d87dbe8"
-  integrity sha512-pGVkY3T/qXxAp2nFPodwYqOevk6ncNMSmvL8QfRCx5ZWGd6Vor7AFNmyaA8Zs6uJyP1QAfjuLandCgvSix1BNA==
-
 electron-to-chromium@^1.5.263:
   version "1.5.282"
   resolved "https://registry.yarnpkg.com/electron-to-chromium/-/electron-to-chromium-1.5.282.tgz#6695816e5b170210d6aa07561546ed7d97347630"
   integrity sha512-FCPkJtpst28UmFzd903iU7PdeVTfY0KAeJy+Lk0GLZRwgwYHn/irRcaCbQQOmr5Vytc/7rcavsYLvTM8RiHYhQ==
 
-emoji-regex@^10.3.0:
-  version "10.6.0"
-  resolved "https://registry.yarnpkg.com/emoji-regex/-/emoji-regex-10.6.0.tgz#bf3d6e8f7f8fd22a65d9703475bc0147357a6b0d"
-  integrity sha512-toUI84YS5YmxW219erniWD0CIVOo46xGKColeNQRgOzDorgBi1v4D71/OFzgD9GO2UGKIv1C3Sp8DAn0+j5w7A==
-
 enhanced-resolve@^5.18.3:
   version "5.18.4"
   resolved "https://registry.yarnpkg.com/enhanced-resolve/-/enhanced-resolve-5.18.4.tgz#c22d33055f3952035ce6a144ce092447c525f828"
@@ -568,7 +523,7 @@ esbuild@^0.27.0:
     "@esbuild/win32-ia32" "0.27.2"
     "@esbuild/win32-x64" "0.27.2"
 
-escalade@^3.1.1, escalade@^3.2.0:
+escalade@^3.2.0:
   version "3.2.0"
   resolved "https://registry.yarnpkg.com/escalade/-/escalade-3.2.0.tgz#011a3f69856ba189dffa7dc8fcce99d2a87903e5"
   integrity sha512-WUj2qlxaQtO4g6Pq5c29GTcWGDyd8itL8zTlipgECz3JesAiiOKotd8JU6otB3PACgG6xkJUyVhboMS+bje/jA==
@@ -588,16 +543,6 @@ fsevents@~2.3.2, fsevents@~2.3.3:
   resolved "https://registry.yarnpkg.com/fsevents/-/fsevents-2.3.3.tgz#cac6407785d03675a2a5e1a5305c697b347d90d6"
   integrity sha512-5xoDfX+fL7faATnagmWPpbFtwh/R77WmMMqqHGS65C3vvB0YHrgF+B1YmZ3441tMj5n63k0212XNoJwzlhffQw==
 
-get-caller-file@^2.0.5:
-  version "2.0.5"
-  resolved "https://registry.yarnpkg.com/get-caller-file/-/get-caller-file-2.0.5.tgz#4f94412a82db32f36e3b0b9741f8a97feb031f7e"
-  integrity sha512-DyFP3BM/3YHTQOCUL/w0OZHR0lpKeGrxotcHWcqNEdnltqFwXVfhEBQ94eIo34AfQpo0rGki4cyIiftY06h2Fg==
-
-get-east-asian-width@^1.0.0, get-east-asian-width@^1.5.0:
-  version "1.6.0"
-  resolved "https://registry.yarnpkg.com/get-east-asian-width/-/get-east-asian-width-1.6.0.tgz#216900f91df11a8b2c198c3e1d93d6c035a776b9"
-  integrity sha512-QRbvDIbx6YklUe6RxeTeleMR0yv3cYH6PsPZHcnVn7xv7zO1BHN8r0XETu8n6Ye3Q+ahtSarc3WgtNWmehIBfA==
-
 graceful-fs@^4.2.4:
   version "4.2.11"
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.2.11.tgz#4183e4e8bf08bb6e05bbb2f7d2e0c8f712ca40e3"
@@ -689,16 +634,6 @@ magic-string@^0.30.21:
   dependencies:
     "@jridgewell/sourcemap-codec" "^1.5.5"
 
-mitt@^3.0.1:
-  version "3.0.1"
-  resolved "https://registry.yarnpkg.com/mitt/-/mitt-3.0.1.tgz#ea36cf0cc30403601ae074c8f77b7092cdab36d1"
-  integrity sha512-vKivATfr97l2/QBCYAkXYDbrIWPM2IIKEl7YPhjCvKlG3kE2gm+uBo6nEXK3M5/Ffh/FLpKExzOQ3JJoJGFKBw==
-
-modern-tar@^0.7.6:
-  version "0.7.7"
-  resolved "https://registry.yarnpkg.com/modern-tar/-/modern-tar-0.7.7.tgz#ca71d79603630076b10733b0751ccab284bbc1ef"
-  integrity sha512-t9VmxaqrmANnEOBhpSDI6HD192Ge48k8vmWqQQL7hSFEqHEYwZbbsu49+aKLWZeRvFs3j1pMhXOqqF4kPlvjkQ==
-
 nanoid@^3.3.11:
   version "3.3.11"
   resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.3.11.tgz#4f4f112cefbe303202f2199838128936266d185b"
@@ -738,18 +673,6 @@ prettier@^3.8.1:
   resolved "https://registry.yarnpkg.com/prettier/-/prettier-3.8.1.tgz#edf48977cf991558f4fcbd8a3ba6015ba2a3a173"
   integrity sha512-UOnG6LftzbdaHZcKoPFtOcCKztrQ57WkHDeRD9t/PTQtmT0NHSeWWepj6pS0z/N7+08BHFDQVUrfmfMRcZwbMg==
 
-puppeteer-core@25.5.0:
-  version "25.5.0"
-  resolved "https://registry.yarnpkg.com/puppeteer-core/-/puppeteer-core-25.5.0.tgz#a41b14d582056b998e0bc3561ac47c7615d38a53"
-  integrity sha512-XPNT0dQJtphqQ4I29zxlG4IIPbg1iEHAQKWuQgtMJGXjACV77pZSmJvDi51IIIfd+DTKICcopJwUx4upVQ4XbA==
-  dependencies:
-    "@puppeteer/browsers" "3.1.0"
-    chromium-bidi "17.0.2"
-    devtools-protocol "0.0.1653615"
-    typed-query-selector "^2.12.2"
-    webdriver-bidi-protocol "0.4.2"
-    ws "^8.21.1"
-
 rollup@^4.43.0:
   version "4.57.0"
   resolved "https://registry.yarnpkg.com/rollup/-/rollup-4.57.0.tgz#9fa13c1fb779d480038f45708b5e01b9449b6853"
@@ -789,30 +712,6 @@ source-map-js@^1.2.1:
   resolved "https://registry.yarnpkg.com/source-map-js/-/source-map-js-1.2.1.tgz#1ce5650fddd87abc099eda37dcff024c2667ae46"
   integrity sha512-UXWMKhLOwVKb728IUtQPXxfYU+usdybtUrK/8uGE8CQMvrhOpwvzDBwj0QhSL7MQc7vIsISBG8VQ8+IDQxpfQA==
 
-string-width@^7.0.0, string-width@^7.2.0:
-  version "7.2.0"
-  resolved "https://registry.yarnpkg.com/string-width/-/string-width-7.2.0.tgz#b5bb8e2165ce275d4d43476dd2700ad9091db6dc"
-  integrity sha512-tsaTIkKW9b4N+AEj+SVA+WhJzV7/zMhcSu78mLKWSk7cXMOSHsBKFWUs0fWwq8QyK3MgJBQRX6Gbi4kYbdvGkQ==
-  dependencies:
-    emoji-regex "^10.3.0"
-    get-east-asian-width "^1.0.0"
-    strip-ansi "^7.1.0"
-
-string-width@^8.2.1:
-  version "8.2.2"
-  resolved "https://registry.yarnpkg.com/string-width/-/string-width-8.2.2.tgz#7310516493df575742fe98af6fae87d85d5ed0ac"
-  integrity sha512-GaPUh5gfdrYzqeVNZvUfT23vYYxXzKYidUcnMtJg/3rxRV63EFZy3k6xfKlmfeJD0176lnUV/Usr3XcwSvFzpg==
-  dependencies:
-    get-east-asian-width "^1.5.0"
-    strip-ansi "^7.1.2"
-
-strip-ansi@^7.1.0, strip-ansi@^7.1.2:
-  version "7.2.0"
-  resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-7.2.0.tgz#d22a269522836a627af8d04b5c3fd2c7fa3e32e3"
-  integrity sha512-yDPMNjp4WyfYBkHnjIRLfca1i6KMyGCtsVgoKe/z1+6vukgaENdgGBZt+ZmKPc4gavvEZ5OgHfHdrazhgNyG7w==
-  dependencies:
-    ansi-regex "^6.2.2"
-
 tailwindcss@4.1.18, tailwindcss@^4.1.18:
   version "4.1.18"
   resolved "https://registry.yarnpkg.com/tailwindcss/-/tailwindcss-4.1.18.tgz#f488ba47853abdb5354daf9679d3e7791fc4f4e3"
@@ -836,11 +735,6 @@ tslib@^2.4.0:
   resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.8.1.tgz#612efe4ed235d567e8aba5f2a5fab70280ade83f"
   integrity sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==
 
-typed-query-selector@^2.12.2:
-  version "2.12.2"
-  resolved "https://registry.yarnpkg.com/typed-query-selector/-/typed-query-selector-2.12.2.tgz#65e2462ac6b0aecfae1bfac1a4f3027070dbabaa"
-  integrity sha512-EOPFbyIub4ngnEdqi2yOcNeDLaX/0jcE1JoAXQDDMIthap7FoN795lc/SHfIq2d416VufXpM8z/lD+WRm2gfOQ==
-
 update-browserslist-db@^1.2.0:
   version "1.2.3"
   resolved "https://registry.yarnpkg.com/update-browserslist-db/-/update-browserslist-db-1.2.3.tgz#64d76db58713136acbeb4c49114366cc6cc2e80d"
@@ -862,49 +756,3 @@ vite@^7.3.1:
     tinyglobby "^0.2.15"
   optionalDependencies:
     fsevents "~2.3.3"
-
-webdriver-bidi-protocol@0.4.2:
-  version "0.4.2"
-  resolved "https://registry.yarnpkg.com/webdriver-bidi-protocol/-/webdriver-bidi-protocol-0.4.2.tgz#f51bb71c2606e90e3d5727607c728b25d617b58b"
-  integrity sha512-VSV+fzfChirL3e7jay2yUC7B4HQCGtEWEg/MSSQbK+qWbqeGlRLlXTzPpYr3XGUvbpDHumWZBJxgesg4N7dbtA==
-
-wrap-ansi@^9.0.0:
-  version "9.0.2"
-  resolved "https://registry.yarnpkg.com/wrap-ansi/-/wrap-ansi-9.0.2.tgz#956832dea9494306e6d209eb871643bb873d7c98"
-  integrity sha512-42AtmgqjV+X1VpdOfyTGOYRi0/zsoLqtXQckTmqTeybT+BDIbM/Guxo7x3pE2vtpr1ok6xRqM9OpBe+Jyoqyww==
-  dependencies:
-    ansi-styles "^6.2.1"
-    string-width "^7.0.0"
-    strip-ansi "^7.1.0"
-
-ws@^8.21.1:
-  version "8.21.3"
-  resolved "https://registry.yarnpkg.com/ws/-/ws-8.21.3.tgz#660b4faddb6a3e575c86e078126919961f4de4fc"
-  integrity sha512-201TZ/kPWxoPr/OKWjquZR1SWKXcvxdH+e1xrx89b3YbmzLMFCLfnaG1HFIgWzJOEWZ7MvpK++odZufgYR50Rw==
-
-y18n@^5.0.5:
-  version "5.0.8"
-  resolved "https://registry.yarnpkg.com/y18n/-/y18n-5.0.8.tgz#7f4934d0f7ca8c56f95314939ddcd2dd91ce1d55"
-  integrity sha512-0pfFzegeDWJHJIAmTLRP2DwHjdF5s7jo9tuztdQxAhINCdvS+3nGINqPd00AphqJR/0LhANUS6/+7SCb98YOfA==
-
-yargs-parser@^22.0.0:
-  version "22.0.0"
-  resolved "https://registry.yarnpkg.com/yargs-parser/-/yargs-parser-22.0.0.tgz#87b82094051b0567717346ecd00fd14804b357c8"
-  integrity sha512-rwu/ClNdSMpkSrUb+d6BRsSkLUq1fmfsY6TOpYzTwvwkg1/NRG85KBy3kq++A8LKQwX6lsu+aWad+2khvuXrqw==
-
-yargs@^18.0.0:
-  version "18.1.0"
-  resolved "https://registry.yarnpkg.com/yargs/-/yargs-18.1.0.tgz#cd7e98c703ef51695bbbf062ed58f28e94291b56"
-  integrity sha512-2rAgRKu54VsHkqI0/tYkmluGXHD4KW7yZoycuqDQ15QOTnc2VVfy0nN/1eMhnQLO00A+dwtK20xuCnc1YGeUyg==
-  dependencies:
-    cliui "^9.0.1"
-    escalade "^3.1.1"
-    get-caller-file "^2.0.5"
-    string-width "^8.2.1"
-    y18n "^5.0.5"
-    yargs-parser "^22.0.0"
-
-zod@^3.24.1:
-  version "3.25.76"
-  resolved "https://registry.yarnpkg.com/zod/-/zod-3.25.76.tgz#26841c3f6fd22a6a2760e7ccb719179768471e34"
-  integrity sha512-gzUt/qt81nXsFGKIFcC3YnfEAx5NkunCfnDlvuBSSFS02bcXu4Lmea0AFIUwbLWxWPx3d9p8S5QoaujKcNQxcQ==