analytics: record and show the rendered content language of page views

GETs store the resolved page language, activity pings carry <html lang> (including a new ping on in-place language switches, which also keeps the switch's GET out of crawler classification), and trail items/crawler hits surface it. The viewer shows flags discreetly: nothing on single-language sites or primary-language-only rows, one leading flag for uniform visits, transition flags on mixed trails, a flag row per crawler.
2026-09-15 05:20:57 +00:00
parent 4cd8dbfc73
commit 3b1804b093
8 changed files with 286 additions and 49 deletions
@@ -38,6 +38,9 @@ Each `Get` record (one per served document):
  (`x-pagerite-preload` header): never counted as a view, crawler hit or
  abuse — recorded only so a navigation later served from the in-memory page
  cache (which issues no GET at all) can be attributed this GET's status,
+- `lang` — rendered content language of the served document (the resolved
+  language of a localized page), `""` for non-localized responses (404
+  probes, reserved paths),
 - `client` — 6-byte blake3 hash referencing `Analytics.clients`.

 304 revalidation responses return before recording and are not logged.
@@ -51,7 +54,9 @@ Each `Msg` record (one per pagerite.js activity message over `/_ws`):
 - `to` — navigation target (validated at record time: internal slug path or
  external https URL; anything else is dropped — sanitation, not
  classification),
- `read` — active seconds spent on `fr` since the previous report.
+- `read` — active seconds spent on `fr` since the previous report,
+- `lang` — rendered language reported by the client for the page the
+  activity happened on (the page's `<html lang>`; `""` from old clients).

 Each `Client` record (shared by every event, keyed by hash):

@@ -104,7 +109,9 @@ The client (`pagerite.js`) keeps a WebSocket connection to `/_ws` for the
 whole browsing session and sends activity messages over it — JSON text
 frames matching the server's `Ping` msgspec struct with the fields `fr`
 (source path), `to` (navigation target), `read` (active seconds on `fr`
-since the last report) and `hide`; falsy fields are omitted. One channel
+since the last report), `lang` (the rendered language of the page the
+activity happened on — its `<html lang>`) and `hide`; falsy fields are
+omitted. One channel
 follows the session, so the activity of a visit stays tied together, and
 while the user is active the accumulated reading time is flushed every few
 seconds: the times are incremental, so a disconnection simply leaves the
@@ -173,10 +180,16 @@ for misses.
  (`_SESSION_GAP`). A fresh page load with an already-open visit (second
  tab) extends it, logging a `(direct)` transition. The visit's trail holds
  first-seen targets in order; `read` updates accumulate active seconds on
-  the trail item matching `fr`. Each trail item's HTTP status comes from
+  the trail item matching `fr` (preferring the item whose language matches
+  the report, so seconds after a language switch land on the new-language
+  step). Each trail item's HTTP status comes from
  the client's latest GET for that path — preloads included, which is what
  allows 404 pages to render red in the viewer even when the navigation
-  itself was served from the page cache. The entry page's referer and
+  itself was served from the page cache. Each trail item also carries the
+  rendered language: the client's report, for the entry page falling back
+  to its GET's rendered language (old clients don't send one); a page
+  re-visited in a different language becomes a distinct trail step instead
+  of merging into the existing item. The entry page's referer and
  `utm_*` tags come from the GET that loaded it (within 10 s before the
  first message).
 - **Crawler hits**: a document GET no activity message matched within
@@ -232,6 +245,10 @@ to tell misses from real pages at a glance.
 The `Display` payload contains the derived `visits`, `crawlers` and `abuse`
 rows (structs `Visit`/`Nav`/`TrailItem`, `CrawlerHit`, `AbuseHit` — display
 DTOs only, never persisted), the visible `clients`, the fetched `favicons`,
+the site language context (`multilingual` — translation languages are
+configured, so the viewer can suppress language UI on single-language
+sites — and `primary_lang` — the front page's primary language, so the
+viewer can skip the primary-language default case),
 and the aggregates below.

 Each derived `Visit`:
@@ -243,8 +260,9 @@ Each derived `Visit`:
 - `trail` — the entry page and everything seen afterwards, keyed by the
  timestamp of first sight (insertion order = first-seen order). Each item
  holds `to` (page path or external exit URL), the accumulated active
-  reading time in seconds (`read`) and the most recent HTTP status seen
-  for the target (`status`),
+  reading time in seconds (`read`), the most recent HTTP status seen
+  for the target (`status`) and the rendered language (`lang`; a page
+  seen in two languages within one visit gets one item per language),
 - `navs` — every navigation (`fr`, `to`), keyed by its timestamp, repeats
  included. The aggregates are computed from this log,
 - `utm` — `utm_*` query parameters from the landing URL, as a dict.
@@ -257,7 +275,8 @@ Each derived `CrawlerHit`:
 - `referer` — external https origin of the request, `""` for direct/none,
 - `query` — raw query string of the request,
 - `status` — HTTP status of the served response (200 for a real page, 404
-  for a category placeholder or missing page).
+  for a category placeholder or missing page),
+- `lang` — rendered content language of the served document (from the GET).

 Each derived `AbuseHit`:

@@ -160,9 +160,15 @@ watch(range, (r) => {

 const clients = computed(() => data.value?.clients || {})
 const favicons = computed(() => data.value?.favicons || {})
-const visitRows = computed(() => formatVisitRows(visits.value, clients.value, pageTree.value, now.value))
+// Site language context from the payload: drives the discreet rendered-
+// language markers in the visit/crawler rows (multilingual sites only).
+const site = computed(() => ({
+  multilingual: !!data.value?.multilingual,
+  primaryLang: data.value?.primary_lang || '',
+}))
+const visitRows = computed(() => formatVisitRows(visits.value, clients.value, pageTree.value, now.value, site.value))
 const crawlers = computed(() => rangeData.value?.crawlers || [])
-const crawlerRows = computed(() => formatCrawlerRows(crawlers.value, clients.value, pageTree.value, now.value))
+const crawlerRows = computed(() => formatCrawlerRows(crawlers.value, clients.value, pageTree.value, now.value, site.value))
 const abuseRows = computed(() => formatAbuseRows(rangeData.value?.abuse || [], clients.value, pageTree.value, now.value))

 </script>
@@ -211,7 +217,8 @@ const abuseRows = computed(() => formatAbuseRows(rangeData.value?.abuse || [], c
                  <td class="trail">
                    <TrailLink v-if="v.refererStep" :step="v.refererStep" :favicons="favicons" @close="$emit('close')" />
                    <span v-if="v.utm && v.utm !== '—'" class="utm-tag small muted" :title="v.utmTitle">{{ v.utm }}</span>
-                    <TrailLink v-for="(s, si) in v.trail" :key="si" :step="s" :favicons="favicons" @close="$emit('close')" />
+                    <span v-if="v.rowFlag" class="flag" v-html="v.rowFlag" :title="v.rowFlagTitle"></span>
+                    <TrailLink v-for="(s, si) in v.trail" :key="si" :step="s" :favicons="favicons" :flags="s.langFlags" @close="$emit('close')" />
                  </td>
                  <VisitorCell
                    :ip="v.ip"
@@ -248,6 +255,7 @@ const abuseRows = computed(() => formatAbuseRows(rangeData.value?.abuse || [], c
                  <td class="trail">
                    <TrailLink v-if="c.refererStep" :step="c.refererStep" :favicons="favicons" @close="$emit('close')" />
                    <TrailLink v-for="(s, si) in c.pages" :key="si" :step="s" :count="s.count" @close="$emit('close')" />
+                    <span v-for="(f, fi) in c.readFlags" :key="fi" class="flag" v-html="f.flag" :title="f.name"></span>
                  </td>
                  <VisitorCell
                    :ip="c.ip"
@@ -484,6 +492,25 @@ const abuseRows = computed(() => formatAbuseRows(rangeData.value?.abuse || [], c
  vertical-align: bottom;
 }

+/* Same flag chip as the visitor cells (VisitorCell.vue); the flags here
+   mark the language the page was read in. */
+.visit-table .flag {
+  display: inline-flex;
+  width: 18px;
+  height: 12px;
+  border-radius: 2px;
+  overflow: hidden;
+  border: 1px solid var(--line);
+  box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.2) inset;
+  vertical-align: middle;
+}
+
+.visit-table .flag :deep(svg) {
+  width: 100%;
+  height: 100%;
+  display: block;
+}
+
 .visit-table .clickable-list {
  cursor: pointer;
  max-width: 22rem;
@@ -6,6 +6,7 @@ const props = defineProps({
  step: { type: Object, required: true },
  count: { type: Number, default: 0 },
  favicons: { type: Object, default: null },
+  flags: { type: Array, default: () => [] },
 })

 defineEmits(['close'])
@@ -38,6 +39,7 @@ const title = computed(() => {
    <small v-if="count > 1" class="muted">{{ formatCount(count) }}×</small>
    <img v-if="favicon" class="favicon" :src="favicon" alt="" />
    <span>{{ step.slug }}</span>
+    <span v-for="(f, fi) in flags" :key="fi" class="flag" v-html="f"></span>
  </a>
 </template>

@@ -48,4 +50,23 @@ const title = computed(() => {
  margin-right: 0.25em;
  vertical-align: -0.1em;
 }
+
+/* Same flag chip as the visitor cells (VisitorCell.vue). */
+.flag {
+  display: inline-flex;
+  width: 18px;
+  height: 12px;
+  margin-left: 0.25em;
+  border-radius: 2px;
+  overflow: hidden;
+  border: 1px solid var(--line);
+  box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.2) inset;
+  vertical-align: middle;
+}
+
+.flag :deep(svg) {
+  width: 100%;
+  height: 100%;
+  display: block;
+}
 </style>
@@ -2,6 +2,7 @@
 * Formatters and aggregators for summary sections: totals and the recent
 * visit trail.
 */
+import { flagFor, langName } from '../langs.js'

 /**
 * IPv4 unchanged, IPv6 returns the /64 network prefix in compact form.
@@ -373,7 +374,7 @@ export function mainDomain(host, limit = 24) {
 * their own site there — rendered with its favicon like visit referers.
 * ``clients`` maps client hashes to client records.
 */
-export function formatCrawlerRows(crawlers, clients, pageTree, now = Date.now()) {
+export function formatCrawlerRows(crawlers, clients, pageTree, now = Date.now(), site = { multilingual: false, primaryLang: '' }) {
  const titles = buildTitleMap(pageTree)
  const groups = new Map()
  for (const c of crawlers || []) {
@@ -384,10 +385,12 @@ export function formatCrawlerRows(crawlers, clients, pageTree, now = Date.now())
      lastStart: 0,
      referer: '',
      pages: new Map(),
+      langs: new Set(),
    }
    const start = new Date(c.start).getTime()
    if (start > g.lastStart) g.lastStart = start
    if (c.referer) g.referer = c.referer
+    if (c.lang) g.langs.add(c.lang)
    if (c.entry?.startsWith('/')) {
      const existing = g.pages.get(c.entry) || { count: 0, status: c.status || 200 }
      existing.count += 1
@@ -408,6 +411,11 @@ export function formatCrawlerRows(crawlers, clients, pageTree, now = Date.now())
      const client = g.client || {}
      const host = client.host || ''
      const isHost = !!host
+      // Rendered languages read, shown only when they say something the
+      // primary language alone would not (multilingual sites only).
+      const langs = [...g.langs].sort()
+      const showLangs =
+        site.multilingual && (langs.length > 1 || (langs[0] && langs[0] !== site.primaryLang))
      return {
        lastSeen: formatWhen(g.lastStart, now),
        lastSeenIso: formatWhenIso(g.lastStart),
@@ -416,6 +424,9 @@ export function formatCrawlerRows(crawlers, clients, pageTree, now = Date.now())
        pages: [...g.pages.entries()]
          .sort((a, b) => b[1].count - a[1].count)
          .map(([path, info]) => ({ ...stepOf(path, titles), count: info.count, status: info.status })),
+        readFlags: showLangs
+          ? langs.map((l) => ({ flag: flagFor(l), name: langName(l) })).filter((f) => f.flag)
+          : [],
        ip: client.ip || '',
        ipDisplay: isHost ? mainDomain(host) : hostIP(client.ip) || client.ip || '—',
        isHost,
@@ -550,23 +561,44 @@ export function formatAbuseRows(abuse, clients, pageTree, now = Date.now()) {
 * Format raw visit records as rows for a technical table.  Returns objects
 * with display strings; missing values become "—".  ``trail`` starts with the
 * external referer (when present), then the entry page and any further internal
- * pages or external exit origins. Only the 20 most recent visits are shown.
- * ``clients`` maps client hashes to client records.
+ * pages or external exit origins; consecutive views of the same page (e.g. a
+ * language switch re-view) merge into one step that keeps the
+ * consecutive-distinct rendered languages, summed read time, and the latest
+ * status.  On multilingual sites the rendered languages surface as flag
+ * icons: a visit read entirely in one non-primary language gets ``rowFlag``,
+ * and a visit spanning languages gets per-step ``langFlags`` markers where
+ * the language begins or changes.  Only the 20 most recent visits are shown.
+ * ``clients`` maps client hashes to client records; ``site`` carries the
+ * payload's multilingual/primary-language context.
 */
-export function formatVisitRows(visits, clients, pageTree, now = Date.now()) {
+export function formatVisitRows(visits, clients, pageTree, now = Date.now(), site = { multilingual: false, primaryLang: '' }) {
  const titles = buildTitleMap(pageTree)
  return [...(visits || [])].reverse().slice(0, 20).map((v) => {
    const client = (clients || {})[v.client] || {}
-    const trail = Object.values(v.trail || {})
+    const steps = Object.values(v.trail || {})
      .map((item) => {
        const step = stepOf(item.to, titles)
        if (step) {
          if (item.read) step.readSeconds = item.read
          if (item.status) step.status = item.status
+          if (item.lang) step.lang = item.lang
        }
        return step
      })
      .filter(Boolean)
+    const trail = []
+    for (const step of steps) {
+      const prev = trail[trail.length - 1]
+      if (prev && prev.path === step.path) {
+        if (step.lang && step.lang !== prev.langs[prev.langs.length - 1]) prev.langs.push(step.lang)
+        if (step.readSeconds) prev.readSeconds = (prev.readSeconds || 0) + step.readSeconds
+        if (step.status) prev.status = step.status
+      } else {
+        step.langs = step.lang ? [step.lang] : []
+        trail.push(step)
+      }
+    }
+    const distinctLangs = new Set(trail.flatMap((s) => s.langs))
    const utmKeys = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content']
    const utmValues = utmKeys.map((k) => (v.utm || {})[k]).filter(Boolean)
    const utm = utmValues.length ? utmValues.join(' · ') : ''
@@ -576,7 +608,7 @@ export function formatVisitRows(visits, clients, pageTree, now = Date.now()) {
    const dash = (s) => (s || '—')
    const host = client.host || ''
    const isHost = !!host
-    return {
+    const row = {
      lastSeen: formatWhen(v.start, now),
      lastSeenIso: formatWhenIso(v.start),
      lastSeenLocal: formatWhenLocal(v.start),
@@ -596,5 +628,27 @@ export function formatVisitRows(visits, clients, pageTree, now = Date.now()) {
      utm: utm || '—',
      utmTitle,
    }
+    if (site.multilingual && distinctLangs.size) {
+      if (distinctLangs.size === 1) {
+        const [tag] = distinctLangs
+        const flag = flagFor(tag)
+        if (flag && tag !== site.primaryLang) {
+          row.rowFlag = flag
+          row.rowFlagTitle = langName(tag)
+        }
+      } else {
+        // Flag the steps where the rendered language begins or changes;
+        // lang-less steps keep the comparison chain going, they never flag.
+        let lastLang = null
+        for (const step of trail) {
+          if (!step.langs.length) continue
+          if (!lastLang || step.langs[step.langs.length - 1] !== lastLang) {
+            step.langFlags = step.langs.map(flagFor).filter(Boolean)
+          }
+          lastLang = step.langs[step.langs.length - 1]
+        }
+      }
+    }
+    return row
  })
 }
@@ -637,6 +637,8 @@ import { reconnectPolicy, socketSlot, watchConnecting } from "./reconnect";
    if (to) msg.to = to;
    const secs = Math.round(read / 1000);
    if (secs > 0) msg.read = secs;
+    const lang = document.documentElement.lang;
+    if (lang) msg.lang = lang;
    if (!msg.to && !msg.read) return;
    report(msg);
  }
@@ -815,6 +817,10 @@ import { reconnectPolicy, socketSlot, watchConnecting } from "./reconnect";
    const y = scrollY; // a language switch is not a navigation: keep scroll
    await load(currentPath, false);
    scrollTo(0, y);
+    // Log the switch as a trail event in the new language (load() updated
+    // <html lang>): the ping matches the switch's GET server-side, so it is
+    // not misclassified as a crawler hit.
+    ping({ to: currentPath });
  });

  // --- Fetch navigation ------------------------------------------------
@@ -2,8 +2,9 @@

 Raw recording, display-time classification.  Every document GET is appended
 to ``Analytics.gets`` as a raw access-log line (path with query string, true
-HTTP status, external referer origin, preload flag) and every pagerite.js
-activity message from the /_ws WebSocket is appended to ``Analytics.msgs``
+HTTP status, external referer origin, preload flag, rendered content
+language) and every pagerite.js activity message from the /_ws WebSocket is
+appended to ``Analytics.msgs``
 (navigations ``fr`` -> ``to`` and active reading-time updates).  Nothing is
 classified when it is recorded: whether a client turns out to be a reader,
 a crawler or a scanner is decided by ``Store.display()`` from the raw
@@ -92,6 +93,9 @@ class Ping(msgspec.Struct, omit_defaults=True):
    read: int = 0
    #: Admin client: record but hide everything from the statistics.
    hide: bool = False
+    #: Rendered language of the page the activity happened on (the page's
+    #: ``<html lang>``, sent by pagerite.js).
+    lang: str = ""


 class Get(msgspec.Struct, omit_defaults=True):
@@ -115,6 +119,9 @@ class Get(msgspec.Struct, omit_defaults=True):
    #: never counted as a view/crawler/abuse hit; recorded only so a later
    #: cache-served navigation can be attributed this GET's status.
    pre: bool = False
+    #: Rendered content language of the served document; "" for
+    #: non-localized responses (404 probes, reserved paths).
+    lang: str = ""


 class Msg(msgspec.Struct, omit_defaults=True):
@@ -135,6 +142,9 @@ class Msg(msgspec.Struct, omit_defaults=True):
    to: str = ""
    #: Active reading time (seconds) spent on ``fr`` since the last report.
    read: int = 0
+    #: Rendered language reported by the client for the page the activity
+    #: happened on.
+    lang: str = ""


 class Client(msgspec.Struct, omit_defaults=True):
@@ -191,6 +201,8 @@ class TrailItem(msgspec.Struct, omit_defaults=True):

    ``read`` accumulates active reading time (seconds) across the whole
    visit; ``status`` is the most recent HTTP status seen for the target.
+    A page seen in two rendered languages within one visit (a mid-article
+    language switch) gets one item per language.
    """

    to: str
@@ -198,6 +210,10 @@ class TrailItem(msgspec.Struct, omit_defaults=True):
    read: int = 0
    #: Most recent HTTP status of the response (200 or 404).
    status: int = 200
+    #: Rendered language of the target: the client's report, for the entry
+    #: page falling back to its GET's rendered language; "" when unknown
+    #: (old clients or data from before language recording).
+    lang: str = ""


 class Visit(msgspec.Struct, omit_defaults=True):
@@ -206,8 +222,9 @@ class Visit(msgspec.Struct, omit_defaults=True):
    ``trail`` holds the entry page and everything seen afterwards, keyed by
    the timestamp of first sight (insertion order = first-seen order);
    re-visiting an already seen target updates its item instead of
-    appending.  Client metadata is held in ``Analytics.clients`` keyed by
-    ``client``.
+    appending — unless the client reports a different rendered language for
+    it, which appends a distinct item (a mid-article language switch).
+    Client metadata is held in ``Analytics.clients`` keyed by ``client``.
    """

    start: datetime
@@ -241,6 +258,8 @@ class CrawlerHit(msgspec.Struct, omit_defaults=True):
    query: str = ""
    #: HTTP status of the served response (200 or 404 for content pages).
    status: int = 200
+    #: Rendered content language of the served document (from the GET).
+    lang: str = ""


 class AbuseHit(msgspec.Struct, omit_defaults=True):
@@ -319,6 +338,12 @@ class Display(msgspec.Struct, omit_defaults=True):
    views: dict[str, dict[str, int]] = {}
    #: New visits per 5-minute bucket: bucket ISO -> count (sparse).
    site_visits: dict[str, int] = {}
+    #: Site context: true when translation languages are configured, so the
+    #: viewer can suppress language UI on single-language sites.
+    multilingual: bool = False
+    #: The site's primary language (the front page's), so the viewer can
+    #: skip the primary-language default case.
+    primary_lang: str = ""


 def _bucket(now: datetime) -> str:
@@ -594,22 +619,25 @@ class Store:
        referer: str = "",
        accept_language: str = "",
        pre: bool = False,
+        lang: str = "",
    ) -> bytes | None:
        """Append one document GET to the raw log.

        ``path`` is the full request path, query string included; ``status``
        the true HTTP status of the response; ``referer`` the raw Referer
        header (reduced here to an external https origin, "" when internal
-        or absent); ``pre`` marks idle-time preloads from pagerite.js.
+        or absent); ``pre`` marks idle-time preloads from pagerite.js;
+        ``lang`` the rendered content language of the served document (""
+        for non-localized responses such as 404 probes and reserved paths).

        Returns the client hash when the client record was just created (so
        the caller can schedule async enrichment), else None.
        """
-        lang, country = _parse_accept_language(accept_language)
-        client_hash = _client_hash(ip, ua, lang)
+        client_lang, country = _parse_accept_language(accept_language)
+        client_hash = _client_hash(ip, ua, client_lang)
        new = client_hash not in self.data.clients
        if new:
-            self._ensure_client(ip, ua, lang, country=country)
+            self._ensure_client(ip, ua, client_lang, country=country)
        self.data.gets.append(
            Get(
                t=datetime.now(UTC),
@@ -618,6 +646,7 @@ class Store:
                status=status,
                ref=_origin(referer) or "",
                pre=pre,
+                lang=lang,
            )
        )
        self._save()
@@ -632,6 +661,7 @@ class Store:
        accept_language: str = "",
        hide: bool = False,
        read: int = 0,
+        lang: str = "",
    ) -> bytes | None:
        """Append one client activity message (``Ping`` from pagerite.js) to
        the raw log.
@@ -642,16 +672,18 @@ class Store:
        stored raw and filtered at display time, so future rule changes lose
        nothing.  ``hide`` flags the client record as an admin; the message
        itself is recorded normally and hidden at display time like
-        everything else the client ever did.
+        everything else the client ever did.  ``lang`` is the rendered
+        language reported by the client for the page the activity happened
+        on.

        Returns the client hash when the client record was just created (so
        the caller can schedule async enrichment), else None.
        """
-        lang, country = _parse_accept_language(accept_language)
-        client_hash = _client_hash(ip, ua, lang)
+        client_lang, country = _parse_accept_language(accept_language)
+        client_hash = _client_hash(ip, ua, client_lang)
        new = client_hash not in self.data.clients
        if new:
-            self._ensure_client(ip, ua, lang, country=country)
+            self._ensure_client(ip, ua, client_lang, country=country)
        if hide:
            self.data.clients[client_hash].hide = True
        fr = (_internal_path(fr) or "") if fr else ""
@@ -663,7 +695,14 @@ class Store:
                target = _external_target(to) or ""
        if target or read > 0:
            self.data.msgs.append(
-                Msg(t=datetime.now(UTC), client=client_hash, fr=fr, to=target, read=read)
+                Msg(
+                    t=datetime.now(UTC),
+                    client=client_hash,
+                    fr=fr,
+                    to=target,
+                    read=read,
+                    lang=lang,
+                )
            )
        if target or read > 0 or hide:
            self._save()
@@ -700,7 +739,13 @@ class Store:
        self.data.favicons[origin] = Favicon(file=file, fetched=datetime.now(UTC))
        self._save()

-    def display(self, in_menu: Callable[[str], bool] | None = None) -> Display:
+    def display(
+        self,
+        in_menu: Callable[[str], bool] | None = None,
+        *,
+        multilingual: bool = False,
+        primary_lang: str = "",
+    ) -> Display:
        """Build the viewer payload from the raw events.

        All classification happens here, so the stored data is independent
@@ -722,10 +767,17 @@ class Store:
        - visits: the remaining messages, grouped per client with a new
          visit after ``_SESSION_GAP`` of inactivity.  Trail statuses come
          from the client's GETs (preloads included — a cache-served
-          navigation's only GET is its preload); the entry referer and UTM
-          tags from the GET that loaded the entry page.
+          navigation's only GET is its preload); trail languages come from
+          the client's messages (the entry item falling back to its GET's
+          rendered language), and a page re-visited in a different rendered
+          language becomes a distinct trail step.  The entry referer and
+          UTM tags come from the GET that loaded the entry page.

        Hidden (admin) clients are excluded from every list and aggregate.
+        ``multilingual`` and ``primary_lang`` are site context (translation
+        languages configured, the front page's primary language) copied
+        onto the payload so the viewer can suppress language UI on
+        single-language sites and skip the primary-language default case.
        """
        in_menu = in_menu or (lambda path: False)
        data = self.data
@@ -836,7 +888,11 @@ class Store:
                                g.path.split("?", 1)[1] if "?" in g.path else ""
                            )
                        visit.trail[m.t] = TrailItem(
-                            to=m.to, status=status_at(h, m.to, m.t)
+                            to=m.to,
+                            status=status_at(h, m.to, m.t),
+                            # The client's report wins; the entry GET fills
+                            # in for old clients that don't send lang.
+                            lang=m.lang or (g.lang if g is not None else ""),
                        )
                        visits.append(visit)
                    else:
@@ -844,18 +900,40 @@ class Store:
                        visit.navs[m.t] = Nav(fr=fr, to=m.to)
                        status = status_at(h, m.to, m.t)
                        # First-seen only: repeat pages and repeated exits
-                        # update the existing trail item instead of appending.
+                        # update the existing trail item instead of
+                        # appending — but a repeat in a different rendered
+                        # language (a mid-article language switch) becomes
+                        # a distinct step.
                        for item in visit.trail.values():
                            if item.to == m.to:
-                                item.status = status
+                                if m.lang and item.lang and m.lang != item.lang:
+                                    visit.trail[m.t] = TrailItem(
+                                        to=m.to, status=status, lang=m.lang
+                                    )
+                                else:
+                                    item.status = status
+                                    if not item.lang:
+                                        item.lang = m.lang
                                break
                        else:
-                            visit.trail[m.t] = TrailItem(to=m.to, status=status)
+                            visit.trail[m.t] = TrailItem(
+                                to=m.to, status=status, lang=m.lang
+                            )
                if m.read > 0 and m.fr and visit is not None:
+                    # A page appears in the trail once per language seen:
+                    # land the seconds on the matching-language step when
+                    # the client reports one, else on the first-seen item.
+                    read_item: TrailItem | None = None
                    for item in visit.trail.values():
-                        if item.to == m.fr:
-                            item.read += m.read
+                        if item.to != m.fr:
+                            continue
+                        if read_item is None:
+                            read_item = item
+                        if m.lang and item.lang == m.lang:
+                            read_item = item
                            break
+                    if read_item is not None:
+                        read_item.read += m.read
                last_t = m.t

        # --- crawler hits: document GETs no message matched
@@ -889,6 +967,7 @@ class Store:
                    referer=g.ref,
                    query=query,
                    status=g.status,
+                    lang=g.lang,
                )
            )

@@ -912,6 +991,7 @@ class Store:
                        referer=visit.referer if first else "",
                        query=query if first else "",
                        status=item.status,
+                        lang=item.lang,
                    )
                )
                first = False
@@ -938,6 +1018,8 @@ class Store:
                for origin, f in data.favicons.items()
                if f.file
            },
+            multilingual=multilingual,
+            primary_lang=primary_lang,
        )
        for visit in kept:
            bucket = _bucket(visit.start)
@@ -959,6 +1041,14 @@ class Store:
                nbuckets[nb] = nbuckets.get(nb, 0) + 1
        return display

-    def display_json(self, in_menu: Callable[[str], bool] | None = None) -> str:
+    def display_json(
+        self,
+        in_menu: Callable[[str], bool] | None = None,
+        *,
+        multilingual: bool = False,
+        primary_lang: str = "",
+    ) -> str:
        """The ``display()`` payload as a JSON string for the WebSocket."""
-        return msgspec.json.encode(self.display(in_menu)).decode()
+        return msgspec.json.encode(
+            self.display(in_menu, multilingual=multilingual, primary_lang=primary_lang)
+        ).decode()
@@ -152,7 +152,8 @@ async def show_page(request: Request, path: str) -> Response:
    if node is not None and node.published and node.chunks is not None:
        # Language selection (docs/localization.md): ?lang= wins when a
        # translation exists, else header logic. Analytics keep the raw
-        # Accept-Language header regardless of the selection.
+        # Accept-Language header regardless of the selection, and record
+        # the resolved language as the GET's rendered language.
        query_lang = request.query_params.get("lang")
        lang = i18n.select_language(
            query_lang,
@@ -175,7 +176,7 @@ async def show_page(request: Request, path: str) -> Response:
        if request.headers.get("if-none-match") == etag:
            return Response(status_code=304)
        if _is_trackable_path(path):
-            _record_get(request)
+            _record_get(request, lang=lang)
        return _html_response(
            request,
            "page",
@@ -205,7 +206,7 @@ async def show_page(request: Request, path: str) -> Response:
        )
        link_lang = i18n.base_tag(query_lang or "")
        if _is_trackable_path(path):
-            _record_get(request, status=404)
+            _record_get(request, status=404, lang=lang)
        return _html_response(
            request,
            "category",
@@ -28,7 +28,7 @@ from fastapi import APIRouter, Request, WebSocket, WebSocketDisconnect
 from fastapi.responses import Response
 from uarite import uaparse

-from pagerite import analytics
+from pagerite import analytics, i18n
 from pagerite.data import resolve
 from pagerite.files import _hash_name, file_store
 from pagerite.state import SITE_URL, _html_response, analytics_store, data
@@ -334,7 +334,7 @@ async def _broadcast_analytics() -> None:
    """Send the current analytics snapshot to every connected WS client."""
    if not _analytics_ws_clients:
        return
-    payload = analytics_store.display_json(_in_menu)
+    payload = _display_json()
    closed = set()
    for ws in _analytics_ws_clients:
        try:
@@ -370,12 +370,29 @@ def _in_menu(path: str) -> bool:
    return resolve(data.menu, path.strip("/")) is not None


-def _record_get(request: Request, *, status: int = 200) -> None:
+def _display_json() -> str:
+    """The current analytics snapshot as JSON for the admin stream.
+
+    Adds the site's language context: ``multilingual`` (translation
+    languages configured) lets the viewer suppress language UI on
+    single-language sites, ``primary_lang`` (the front page's) lets it skip
+    the primary-language default case.
+    """
+    return analytics_store.display_json(
+        _in_menu,
+        multilingual=bool(data.translate_langs),
+        primary_lang=i18n.primary_lang(data.menu, ""),
+    )
+
+
+def _record_get(request: Request, *, status: int = 200, lang: str = "") -> None:
    """Record the document GET as one raw access-log line in analytics.

    Nothing is classified here — the true HTTP status, the full request path
-    (query included), an external referer origin and the preload flag are
-    stored, and visitor/crawler/abuse classification happens at display time
+    (query included), an external referer origin, the preload flag and the
+    rendered content language (``lang``, "" for non-localized responses such
+    as 404 probes and reserved paths) are stored, and
+    visitor/crawler/abuse classification happens at display time
    (see analytics.Store.display).  Idle-time preloads from pagerite.js
    (``x-pagerite-preload`` header) are recorded with ``pre=True``: never
    counted, but a navigation later served from the in-memory page cache is
@@ -403,6 +420,7 @@ def _record_get(request: Request, *, status: int = 200) -> None:
        referer=referer,
        accept_language=request.headers.get("accept-language", ""),
        pre=bool(request.headers.get("x-pagerite-preload")),
+        lang=lang,
    )
    if client_hash is not None:
        _schedule_client_enrichment([client_hash])
@@ -462,6 +480,7 @@ async def activity_ws(ws: WebSocket) -> None:
                accept_language,
                hide=msg.hide,
                read=msg.read,
+                lang=msg.lang,
            )
            if new_client is not None:
                _schedule_client_enrichment([new_client])
@@ -478,7 +497,7 @@ async def analytics_websocket(ws: WebSocket) -> None:
    endpoint. Powers the analytics viewer rendered at /_a.
    """
    await ws.accept()
-    await ws.send_text(analytics_store.display_json(_in_menu))
+    await ws.send_text(_display_json())
    _analytics_ws_clients.add(ws)
    try:
        while True: