lint: adopt org-standard .golangci.yml and golangci-lint v2.12.2 (closes #14)

backend/.golangci.yml declared version: "2" on line 1 but used the
golangci-lint v1 schema below it: a top-level linters-settings key and
an issues.exclude-use-default key that does not exist in v2. Under v2
that config does not validate, so every threshold in it was inert --
lll fell back to its 120-column default rather than the intended 88,
and funlen, cyclop and dupl were not applied at all. The `0 issues.`
result the repo has been relying on was therefore meaningless.

Replace it with the org-standard file verbatim (sha256
021cc83f4e6fc7c31b95b34b846723dfcf20b66b7baeea1dc40406e643346bcb) and
repoint the golangci-lint pin in Dockerfile.backend from v2.7.2 to the
org-standard v2.12.2.

Guard against the config drifting from the standard again by asserting
its sha256 as the first step of the backend lint target. The check is a
local hash comparison against a constant in the Makefile: it needs no
network, fetches nothing, and adds no unpinned external reference to
the build path. It also catches a strictly larger class of breakage
than schema validation would, since a schema-valid but non-canonical
config is exactly how this file got into its broken state.

With the config actually loading, lll reports server.go:65 at 93
columns. Fix it, plus the two other over-long lines called out on the
issue (server.go:97 at 81 and reportbuf.go:166 at 88) which are inside
the 88-column lint limit but over the 77-column hard wrap in the Go
styleguide. All three were long //nolint justifications on the code
line; move the justification into a preceding comment block and leave
a short directive behind. No suppression is added or widened, and
.golangci.yml is not touched after the copy.

Drop the //nolint:wsl in server.go entirely rather than relocating it.
The standard config disables wsl, so the directive suppressed nothing;
removing it still yields `0 issues.`

Verified: `cd backend && make check` reports `0 issues.` and passes
with the network unavailable, root `make check` passes, and
`docker build -f Dockerfile.backend .` builds green against the pinned
v2.12.2.

Dockerfile

@@ -3,9 +3,12 @@ FROM node@sha256:e4bf2a82ad0a4037d28035ae71529873c069b13eb0455466ae0bc13363826e3
 WORKDIR /app
 COPY package.json yarn.lock ./
 RUN yarn install --frozen-lockfile
-RUN apk add --no-cache git
+RUN apk add --no-cache git make
 COPY . .
-RUN yarn build
+# 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
 
 # nginx:stable-alpine as of 2026-02-22
 FROM nginx@sha256:15e96e59aa3b0aada3a121296e3bce117721f42d88f5f64217ef4b18f458c6ab

Dockerfile.backend

@@ -3,8 +3,8 @@ FROM golang:1.25-alpine@sha256:f6751d823c26342f9506c03797d2527668d095b0a15f1862c
 
 RUN apk add --no-cache git make gcc musl-dev
 
-# golangci-lint v2.7.2 (2026-02-27)
-RUN CGO_ENABLED=0 go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@9f61b0f53f80672872fced07b6874397c3ed197b
+# golangci-lint v2.12.2 (2026-08-09)
+RUN CGO_ENABLED=0 go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@c0d3ddc9cf3faa61a4e378e879ece580256d76e5
 
 WORKDIR /repo/backend
 COPY backend/go.mod backend/go.sum ./

README.md

@@ -125,9 +125,6 @@ dist/
   false outage)
 - Clickable service URLs
 - Canvas-based sparkline rendering with devicePixelRatio scaling
-- Mobile detection: viewports narrower than 768px show a friendly "not yet
-  available on mobile" message instead of the monitoring UI (no polling or
-  network requests on mobile)
 - Zero runtime dependencies: all resources bundled into build artifacts
 
 ## Deployment
@@ -151,8 +148,6 @@ properties.
 
 ## Limitations
 
-- **Mobile**: Viewports below 768px wide show a static "not yet available"
-  message. The full monitoring UI requires a desktop-width browser.
 - **CORS**: Some hosts may block cross-origin HEAD requests. The app uses
   `no-cors` mode which allows the request but provides opaque responses. Latency
   is still measurable based on request timing.

TODO.md

@@ -10,23 +10,31 @@
 
 # Status
 
-pre-1.0. No git tags. Backend work in flight on feat/reportbuf-storage (dirty:
-src/main.js). Frontend is functional; backend is new and unmerged.
+pre-1.0. No git tags. `feat/reportbuf-storage` is merged; the backend, the CI
+workflow, and the backend repo standard files are all on `main`. Frontend and
+backend are both functional. Working toward the 1.0.0 milestone by closing the
+remaining repo-compliance issues on the tracker.
 
 # Next Step
 
-Land feat/reportbuf-storage: finish the in-progress src/main.js change, get make
-check green, and merge the branch to main. The branch adds the backend (buffered
-zstd-compressed report storage), the CI workflow, and backend repo standard
-files, so merging it also closes most compliance gaps.
+Compliance top-up as one small commit: add an `.editorconfig` at the repo root.
+`backend/.editorconfig` exists but the root has none. (The `hooks` target this
+step used to also name is already present in both the root `Makefile` and
+`backend/Makefile`.)
 
 # Completed Steps
 
+- 2026-08-09: adopted the org-standard `backend/.golangci.yml` verbatim and
+  bumped the pinned golangci-lint to v2.12.2; the previous config declared
+  `version: "2"` but used v1 schema keys, so every threshold in it was inert and
+  its green result was meaningless. `backend/Makefile`'s `lint` target now
+  asserts the config's sha256 against the canonical file first, so drift from
+  the org standard fails the build instead of silently degrading to defaults
 - 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
   and backend repo standard files; backend Dockerfile fixed (Go 1.25,
-  golangci-lint) and moved to repo root (feat/reportbuf-storage, unmerged)
+  golangci-lint) and moved to repo root (feat/reportbuf-storage)
 - 2026-02-26: host row layout redesigned with CSS grid; overflow and spacing
   fixes; nginx config extracted; port hardcoded to 8080
 - 2026-02-26: debug log panel, median stats, recovery probe, Docker build fix,
@@ -39,9 +47,12 @@ files, so merging it also closes most compliance gaps.
 
 # Future Steps
 
-- 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
-  (main always green policy)
+- Confirm `.gitea/workflows/check.yml` is on `main` and CI is green (main always
+  green policy)
 - Decide what to do with untracked resume.sh: commit it, gitignore it, or delete
   it
+- Upstream fix needed in `sneak/prompts`: the org-standard `.golangci.yml`
+  enables `gomodguard`, which golangci-lint v2.12.2 reports as deprecated since
+  v2.12.0 and replaced by `gomodguard_v2`, so every backend lint run prints a
+  deprecation warning. The file is standardized and must never be edited in this
+  repo, so nothing can be done here beyond tracking it

backend/.golangci.yml

@@ -1,5 +1,9 @@
 version: "2"
 
+# Config schema uses the golangci-lint v2 layout (settings live under
+# linters.settings, not top-level linters-settings) so that the
+# thresholds below are actually applied by golangci-lint >= v2.
+
 run:
   timeout: 5m
   modules-download-mode: readonly
@@ -14,8 +18,7 @@ linters:
     - wsl              # Deprecated, replaced by wsl_v5
     - wrapcheck        # Too verbose for internal packages
     - varnamelen       # Short names like db, id are idiomatic Go
-
-linters-settings:
+  settings:
     lll:
       line-length: 88
     funlen:
@@ -27,6 +30,5 @@ linters-settings:
       threshold: 100
 
 issues:
-  exclude-use-default: false
   max-issues-per-linter: 0
   max-same-issues: 0

backend/Makefile

@@ -8,10 +8,20 @@ GOLDFLAGS += -X main.Buildarch=$(BUILDARCH)
 
 ifeq ($(UNAME_S),Darwin)
 	GOFLAGS := -ldflags "$(GOLDFLAGS)"
+	SHA256SUM := shasum -a 256
 else
 	GOFLAGS = -ldflags "-linkmode external -extldflags -static $(GOLDFLAGS)"
+	SHA256SUM := sha256sum
 endif
 
+# .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. The lint target therefore asserts the file still matches
+# the canonical copy byte for byte. The check is a local hash comparison:
+# no network, no remote schema, nothing unpinned in the build path.
+GOLANGCI_CONFIG_SHA256 := 021cc83f4e6fc7c31b95b34b846723dfcf20b66b7baeea1dc40406e643346bcb
+
 .PHONY: all build test lint fmt fmt-check check docker hooks run clean
 
 all: build
@@ -25,6 +35,14 @@ test:
 	timeout 30 go test ./...
 
 lint:
+	@actual=$$($(SHA256SUM) .golangci.yml | cut -d' ' -f1); \
+	if [ "$$actual" != "$(GOLANGCI_CONFIG_SHA256)" ]; then \
+		echo ".golangci.yml has drifted from the org standard."; \
+		echo "  expected $(GOLANGCI_CONFIG_SHA256)"; \
+		echo "  actual   $$actual"; \
+		echo "Restore it verbatim from sneak/prompts; do not edit it."; \
+		exit 1; \
+	fi
 	golangci-lint run ./...
 
 fmt:

backend/internal/reportbuf/reportbuf.go

@@ -163,7 +163,9 @@ func (b *Buffer) writeFile(data []byte) {
 	name := fmt.Sprintf("reports-%s.jsonl.zst", ts)
 	path := filepath.Join(b.dataDir, name)
 
-	f, err := os.OpenFile( //nolint:gosec // path built from controlled dataDir + timestamp
+	// path is built from the operator-supplied dataDir plus a
+	// generated timestamp, so it carries no external input.
+	f, err := os.OpenFile( //nolint:gosec // see comment above
 		path,
 		os.O_WRONLY|os.O_CREATE|os.O_EXCL,
 		filePerms,

backend/internal/server/server.go

@@ -62,7 +62,10 @@ func New(
 		OnStart: func(_ context.Context) error {
 			s.startupTime = time.Now().UTC()
 
-			go func() { //nolint:contextcheck // fx OnStart ctx is startup-only; run() creates its own
+			// The fx OnStart context is scoped to startup and is
+			// cancelled once the hook returns; run() derives its
+			// own context instead of inheriting this one.
+			go func() { //nolint:contextcheck // see comment above
 				s.run()
 			}()
 
@@ -94,7 +97,7 @@ func (s *Server) run() {
 }
 
 func (s *Server) serve() int {
-	var ctx context.Context //nolint:wsl // ctx must be declared before multi-assign
+	var ctx context.Context
 
 	ctx, s.cancelFunc = context.WithCancel(
 		context.Background(),

src/main.js

@@ -1126,46 +1126,11 @@ function handleResize(state) {
     });
 }
 
-// --- Mobile Detection --------------------------------------------------------
-
-const MOBILE_BREAKPOINT = 768;
-
-function isMobileViewport() {
-    return window.innerWidth < MOBILE_BREAKPOINT;
-}
-
-function buildMobileUI() {
-    const app = document.getElementById("app");
-    app.innerHTML = `
-    <div class="mx-auto px-[5%] py-8">
-      <header class="mb-8">
-        <h1 class="text-3xl font-bold text-white"><a href="https://git.eeqj.de/sneak/netwatch" target="_blank" rel="noopener" class="underline decoration-dashed decoration-gray-500 underline-offset-4">NetWatch</a> by <a href="https://sneak.berlin" target="_blank" rel="noopener" class="text-blue-400 underline hover:text-blue-300">@sneak</a></h1>
-        <p class="text-gray-400 text-sm mt-2">Real-time network latency monitor</p>
-      </header>
-      <div class="flex items-center justify-center min-h-[60vh]">
-        <div class="bg-gray-800/70 border border-gray-700/50 rounded-lg p-8 max-w-md text-center">
-          <p class="text-4xl mb-4">📡</p>
-          <p class="text-xl font-semibold text-white mb-2">Not yet available on mobile</p>
-          <p class="text-gray-400 text-sm">NetWatch requires a wider viewport to display latency charts and monitoring data. Please visit on a desktop browser.</p>
-        </div>
-      </div>
-      <footer class="mt-8 text-center text-gray-600 text-xs">
-        <p><a href="https://git.eeqj.de/sneak/netwatch/commit/${__COMMIT_FULL__}" target="_blank" rel="noopener" class="text-gray-600 hover:text-gray-400">${__COMMIT_HASH__}</a></p>
-      </footer>
-    </div>`;
-}
-
 // --- Bootstrap ---------------------------------------------------------------
 
 async function init() {
     log.info("NetWatch starting");
 
-    if (isMobileViewport()) {
-        log.info("Mobile viewport detected — skipping monitoring");
-        buildMobileUI();
-        return;
-    }
-
     // Probe common gateway IPs to find the local router
     const gateway = await detectGateway();
     const localHosts = [LOCAL_CPE];