diff --git a/apps/website/package.json b/apps/website/package.json
index 0ac90ae092..7e443d7e1a 100644
--- a/apps/website/package.json
+++ b/apps/website/package.json
@@ -14,6 +14,7 @@
     "check:queen-spec-mirrors": "node --experimental-strip-types qa/queen-spec-mirrors.mjs",
     "check:queen-responsive": "node --experimental-strip-types qa/queen-responsive.mjs",
     "check:spec-catalog": "node --experimental-strip-types qa/spec-catalog-contract.mjs",
+    "check:traffic-arrival": "node --experimental-strip-types qa/traffic-arrival-contract.mjs",
     "core": "node scripts/spec-core.mjs",
     "check:shared-core": "node --experimental-strip-types qa/shared-spec-core.mjs",
     "prebuild": "npm run core -- index && node scripts/skills-core.mjs index && node scripts/agents-from-specs.mjs && node scripts/docs-from-specs.mjs && node scripts/viewport-from-spec.mjs && node scripts/onboarding-from-spec.mjs && node scripts/queen-wars-from-spec.mjs",
diff --git a/apps/website/qa/traffic-arrival-contract.mjs b/apps/website/qa/traffic-arrival-contract.mjs
new file mode 100644
index 0000000000..1c008a7c0f
--- /dev/null
+++ b/apps/website/qa/traffic-arrival-contract.mjs
@@ -0,0 +1,29 @@
+// THE ARRIVAL HALF OF THE CHANNEL TAGS: a tagged visit to t27.ai is reported
+// once, untagged visits never, and a failure never reaches the page.
+// Run: node --experimental-strip-types qa/traffic-arrival-contract.mjs
+import assert from 'node:assert/strict'
+import { arrivalFromSearch, reportArrival, ARRIVAL_URL } from '../src/lib/trafficArrival.ts'
+
+// The form the agents publish: the query BEFORE the hash route.
+const blog = new URL('https://t27.ai/?utm_source=x&utm_medium=social&utm_campaign=blog&utm_content=gf-t#/blog/gf-t')
+assert.deepEqual(arrivalFromSearch(blog.search), {
+  source: 'x', medium: 'social', campaign: 'blog', content: 'gf-t',
+})
+assert.equal(arrivalFromSearch(''), null, 'no tags, no arrival')
+assert.equal(arrivalFromSearch('?utm_medium=social'), null, 'no source, no arrival')
+// A query written after the hash is part of the route: not ours to read here.
+assert.equal(arrivalFromSearch(new URL('https://t27.ai/#/blog/s?utm_source=x').search), null)
+
+const store = new Map()
+const storage = { getItem: k => store.get(k) ?? null, setItem: (k, v) => void store.set(k, v) }
+const calls = []
+const send = async (url, init) => { calls.push([url, JSON.parse(init.body)]); return new Response('{}') }
+assert.equal(await reportArrival('?utm_source=reddit', send, storage), true)
+assert.equal(await reportArrival('?utm_source=reddit', send, storage), false, 'once per session')
+assert.equal(await reportArrival('', send, new Map() && { getItem: () => null, setItem: () => {} }), false)
+assert.deepEqual(calls, [[ARRIVAL_URL, { source: 'reddit' }]])
+
+const failing = async () => { throw new Error('offline') }
+assert.equal(await reportArrival('?utm_source=threads', failing, { getItem: () => null, setItem: () => {} }), false)
+
+console.log('traffic-arrival contract: 9 checks passed')
diff --git a/apps/website/src/lib/trafficArrival.ts b/apps/website/src/lib/trafficArrival.ts
new file mode 100644
index 0000000000..8f62bb9a6d
--- /dev/null
+++ b/apps/website/src/lib/trafficArrival.ts
@@ -0,0 +1,71 @@
+/**
+ * A VISITOR FROM A TAGGED LINK IS COUNTED ONCE, BY CHANNEL.
+ *
+ * The agents publish blog links with their channel in the address
+ * (`https://t27.ai/?utm_source=x&utm_campaign=blog&utm_content=<slug>#/blog/<slug>`,
+ * 999-multibots-telegraf render/src/agent/utm.ts). Tags on a link count
+ * nothing by themselves: this is the arrival half. On load the page reads
+ * the tags from its own query -- BEFORE the `#`, where HashRouter leaves
+ * them -- and tells the render service once per browser session, which
+ * keeps a count per (day, channel) and nothing else: no IP, no user id.
+ *
+ * No tags, no call. A failed call is dropped; the page never waits on it.
+ */
+export const ARRIVAL_URL =
+  'https://vibee-render-production.up.railway.app/api/traffic/arrival'
+
+export interface ArrivalTags {
+  source: string
+  medium?: string
+  campaign?: string
+  content?: string
+}
+
+/** The utm tags of a query string, or null when it names no source. Pure. */
+export function arrivalFromSearch(search: string): ArrivalTags | null {
+  const q = new URLSearchParams(search.startsWith('?') ? search : `?${search}`)
+  const source = (q.get('utm_source') ?? '').trim()
+  if (!source) return null
+  const tags: ArrivalTags = { source }
+  const more: Array<[string, 'medium' | 'campaign' | 'content']> = [
+    ['utm_medium', 'medium'],
+    ['utm_campaign', 'campaign'],
+    ['utm_content', 'content'],
+  ]
+  for (const [k, key] of more) {
+    const v = (q.get(k) ?? '').trim()
+    if (v) tags[key] = v
+  }
+  return tags
+}
+
+const ONCE_KEY = 'traffic:arrival-reported'
+
+/** Report this visit's tags, once per browser session. Never throws. */
+export async function reportArrival(
+  search: string = typeof window !== 'undefined' ? window.location.search : '',
+  send: typeof fetch = fetch,
+  storage: Pick<Storage, 'getItem' | 'setItem'> | null = typeof sessionStorage !== 'undefined'
+    ? sessionStorage
+    : null
+): Promise<boolean> {
+  const tags = arrivalFromSearch(search)
+  if (!tags) return false
+  try {
+    if (storage?.getItem(ONCE_KEY)) return false
+    storage?.setItem(ONCE_KEY, '1')
+  } catch {
+    /* no storage: count anyway */
+  }
+  try {
+    await send(ARRIVAL_URL, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify(tags),
+      keepalive: true,
+    })
+    return true
+  } catch {
+    return false
+  }
+}
diff --git a/apps/website/src/main.tsx b/apps/website/src/main.tsx
index 5d737c2f91..7b65e21917 100644
--- a/apps/website/src/main.tsx
+++ b/apps/website/src/main.tsx
@@ -12,6 +12,7 @@ import GlobalStarfield from './components/GlobalStarfield.tsx'
 import { handExplorerLinksToQueen } from './lib/queenFrame'
 import { redirectLegacyQueen } from './lib/legacyQueenRedirect'
 import { triIdentity } from './lib/triIdentity'
+import { reportArrival } from './lib/trafficArrival'
 
 // THE QUEEN MOVED to https://app.t27.ai/queen/, which now builds this same
 // bundle and serves the board on the app's own origin. #/queen here is the old
@@ -27,6 +28,11 @@ import { triIdentity } from './lib/triIdentity'
 // which calls the decision with both origins as input.
 const leaving = redirectLegacyQueen()
 
+// A visitor from a tagged link (utm_source=x, reddit, threads...) is counted
+// once, by channel, where the agents' links land. Not for a page that is on
+// its way to another address. See src/lib/trafficArrival.ts.
+if (!leaving) void reportArrival()
+
 // In a Queen tab's frame, a link to another Explorer switches the Queen's tab instead
 // of navigating the frame under a rail that names a different one.
 handExplorerLinksToQueen()