diff --git a/README.md b/README.md
index be43ba9..84d28ee 100644
--- a/README.md
+++ b/README.md
@@ -97,7 +97,34 @@ reconciliation; this change does not immediately rewrite or restart them.
 Servers with an unknown map retain their existing config behavior. Rollback
 restores the exact prior config bytes.
 
-## Tests
+## Round telemetry experiment
+
+Send `POST /api/telemetry` with `Content-Type: application/json` to the Electric
+Cherry host (port 3000 in local development):
+
+```bash
+curl http://localhost:3000/api/telemetry \
+  -H 'Content-Type: application/json' \
+  -d '{"event":"round_change","round":17,"server":"t5_zombie_prototype_1","players":4}'
+```
+
+The server must already be registered in Electric Cherry. `round` and `players`
+are required nonnegative integers. Success returns HTTP 200 with
+`{ "ok": true, "telemetry": { "server": "...", "round": 17, "players": 4, "receivedAt": "..." } }`.
+Invalid payloads return 400, unknown/destroyed servers 404, and non-JSON content
+types 415. This endpoint uses the app's existing LAN/Tailscale access model;
+there is no API key requirement.
+
+The latest report is saved across app restarts and streamed immediately to the
+dashboard and server detail page, including after browser reconnection. The UI
+labels it as the last reported round with its age: round-change events alone
+cannot detect a stopped script or a match ending. Send the initial round on each
+new match, then each round change. The latest received request wins (including
+lower rounds for new matches); there is no event ordering or history yet.
+Telemetry player counts are displayed with the report and never replace RCON
+occupancy or affect automated restart gates.
+
+## Running tests
 
 ```bash
 npm test
diff --git a/src/lib/server/db/schema.sql b/src/lib/server/db/schema.sql
index 9410983..8a21957 100644
--- a/src/lib/server/db/schema.sql
+++ b/src/lib/server/db/schema.sql
@@ -242,3 +242,9 @@ CREATE TABLE IF NOT EXISTS settings (
     key   TEXT PRIMARY KEY,
     value TEXT NOT NULL
 );
+CREATE TABLE IF NOT EXISTS server_telemetry (
+    server TEXT PRIMARY KEY REFERENCES servers(name) ON DELETE CASCADE,
+    round INTEGER NOT NULL,
+    players INTEGER NOT NULL,
+    received_at TEXT NOT NULL
+);
diff --git a/src/lib/server/fleet/telemetry.ts b/src/lib/server/fleet/telemetry.ts
new file mode 100644
index 0000000..3d64ef3
--- /dev/null
+++ b/src/lib/server/fleet/telemetry.ts
@@ -0,0 +1,15 @@
+import { db } from '../db/index.js';
+import type { RoundTelemetry } from '../../telemetry.js';
+
+export function listTelemetry(): RoundTelemetry[] {
+    return db().prepare(`SELECT t.server, t.round, t.players, t.received_at AS receivedAt
+        FROM server_telemetry t JOIN servers s ON s.name = t.server
+        WHERE s.destroyed_at IS NULL`).all() as RoundTelemetry[];
+}
+
+export function saveTelemetry(report: RoundTelemetry): void {
+    db().prepare(`INSERT INTO server_telemetry (server, round, players, received_at)
+        VALUES (?, ?, ?, ?) ON CONFLICT(server) DO UPDATE SET
+        round = excluded.round, players = excluded.players, received_at = excluded.received_at`)
+        .run(report.server, report.round, report.players, report.receivedAt);
+}
diff --git a/src/lib/server/pipeline/bus.ts b/src/lib/server/pipeline/bus.ts
index b408b3b..b4f08b1 100644
--- a/src/lib/server/pipeline/bus.ts
+++ b/src/lib/server/pipeline/bus.ts
@@ -1,4 +1,5 @@
 import { EventEmitter } from 'node:events';
+import type { RoundTelemetry } from '../../telemetry.js';
 import type { RconEndpoint, RconFailure, RconPlayer } from '../integrations/rcon.js';
 import type { Health } from '../fleet/health.js';
 
@@ -36,6 +37,7 @@ export type BetaStage =
 export type BetaState = 'running' | 'ready-promote' | 'promoted' | 'rolled-back';
 
 export type PipelineEvent =
+    | { type: 'server-telemetry'; entries: RoundTelemetry[] }
     | { type: 'deployment-opened'; deploymentId: string; action: string; servers: string[] }
     | { type: 'server-changed'; deploymentId: string; server: string; files: number }
     | {
diff --git a/src/lib/telemetry.ts b/src/lib/telemetry.ts
new file mode 100644
index 0000000..e1c2f3c
--- /dev/null
+++ b/src/lib/telemetry.ts
@@ -0,0 +1,6 @@
+export interface RoundTelemetry {
+    server: string;
+    round: number;
+    players: number;
+    receivedAt: string;
+}
diff --git a/src/lib/ui/components/RoundTelemetry.svelte b/src/lib/ui/components/RoundTelemetry.svelte
new file mode 100644
index 0000000..3a5cd20
--- /dev/null
+++ b/src/lib/ui/components/RoundTelemetry.svelte
@@ -0,0 +1,19 @@
+<script lang="ts">
+    import { telemetryByServer, uiNow } from '$ui/stores/servers.js';
+    import { elapsedSince } from '$ui/duration.js';
+    let { name }: { name: string } = $props();
+    let report = $derived($telemetryByServer.get(name));
+</script>
+
+{#if report}
+    <div class="round" aria-live="polite">
+        <strong>Round {report.round}</strong>
+        <span title={report.receivedAt}>Last reported {elapsedSince(report.receivedAt, $uiNow)} ago · {report.players} players</span>
+    </div>
+{/if}
+
+<style>
+    .round { display: flex; flex-wrap: wrap; align-items: baseline; gap: var(--space-2); }
+    strong { color: var(--text-primary); font-family: var(--font-mono); }
+    span { color: var(--text-tertiary); font-size: var(--text-xs); }
+</style>
diff --git a/src/lib/ui/components/ServerCard.svelte b/src/lib/ui/components/ServerCard.svelte
index 5d01c64..ceff928 100644
--- a/src/lib/ui/components/ServerCard.svelte
+++ b/src/lib/ui/components/ServerCard.svelte
@@ -1,4 +1,5 @@
 <script lang="ts">
+    import RoundTelemetry from './RoundTelemetry.svelte';
     import type { RosterPlayer, Health } from '$ui/stores/servers.js';
     import { uiNow } from '$ui/stores/servers.js';
     import { gametypeLabel } from '$ui/gametype.js';
@@ -118,6 +119,8 @@
         {/if}
     </div>
 
+    <RoundTelemetry {name} />
+
     {#if showTiming}
         <div class="timing">
             {#if activeElapsed}
diff --git a/src/lib/ui/stores/servers.ts b/src/lib/ui/stores/servers.ts
index 5e68888..aa6682e 100644
--- a/src/lib/ui/stores/servers.ts
+++ b/src/lib/ui/stores/servers.ts
@@ -1,5 +1,8 @@
 import { writable, readonly } from 'svelte/store';
 import { browser } from '$app/environment';
+import type { RoundTelemetry } from '$lib/telemetry.js';
+
+export const telemetryByServer = writable<Map<string, RoundTelemetry>>(new Map());
 
 export interface RosterPlayer {
     num: number | null;
@@ -49,6 +52,14 @@ let source: EventSource | null = null;
 export function startServerStream(): void {
     if (!browser || source) return;
     source = new EventSource('/api/events/servers');
+    source.addEventListener('server-telemetry', (evt) => {
+        const data = JSON.parse((evt as MessageEvent).data) as { entries: RoundTelemetry[]; snapshot?: boolean };
+        telemetryByServer.update((previous) => {
+            const next = data.snapshot ? new Map<string, RoundTelemetry>() : new Map(previous);
+            for (const entry of data.entries) next.set(entry.server, entry);
+            return next;
+        });
+    });
     source.addEventListener('server-status', (evt) => {
         const data = JSON.parse((evt as MessageEvent).data) as { entries: ServerStatus[] };
         statusByServer.update(() => {
diff --git a/src/routes/api/events/servers/+server.ts b/src/routes/api/events/servers/+server.ts
index a673cd6..ef176ab 100644
--- a/src/routes/api/events/servers/+server.ts
+++ b/src/routes/api/events/servers/+server.ts
@@ -1,4 +1,5 @@
 import { subscribe } from '$lib/server/pipeline/bus.js';
+import { listTelemetry } from '$lib/server/fleet/telemetry.js';
 
 const encoder = new TextEncoder();
 const HEARTBEAT_MS = 20_000;
@@ -10,11 +11,12 @@ export async function GET() {
     const stream = new ReadableStream<Uint8Array>({
         start(controller) {
             unsubscribe = subscribe((event) => {
-                if (event.type === 'server-status') {
-                    controller.enqueue(encoder.encode(`event: server-status\ndata: ${JSON.stringify(event)}\n\n`));
+                if (event.type === 'server-status' || event.type === 'server-telemetry') {
+                    controller.enqueue(encoder.encode(`event: ${event.type}\ndata: ${JSON.stringify(event)}\n\n`));
                 }
             });
             controller.enqueue(encoder.encode(': hello\n\n'));
+            controller.enqueue(encoder.encode(`event: server-telemetry\ndata: ${JSON.stringify({ entries: listTelemetry(), snapshot: true })}\n\n`));
             heartbeat = setInterval(() => controller.enqueue(encoder.encode(': ping\n\n')), HEARTBEAT_MS);
         },
         cancel() {
diff --git a/src/routes/api/telemetry/+server.ts b/src/routes/api/telemetry/+server.ts
new file mode 100644
index 0000000..75434fa
--- /dev/null
+++ b/src/routes/api/telemetry/+server.ts
@@ -0,0 +1,29 @@
+import { json } from '@sveltejs/kit';
+import { getServer } from '$lib/server/fleet/servers.js';
+import { saveTelemetry } from '$lib/server/fleet/telemetry.js';
+import { emit } from '$lib/server/pipeline/bus.js';
+
+export async function POST({ request }: { request: Request }) {
+    if (request.headers.get('content-type')?.split(';')[0].trim().toLowerCase() !== 'application/json') {
+        return json({ ok: false, error: 'Content-Type must be application/json' }, { status: 415 });
+    }
+    const body = await request.json().catch(() => null);
+    if (!body || typeof body !== 'object' || Array.isArray(body)
+        || body.event !== 'round_change'
+        || typeof body.server !== 'string' || !body.server.length || body.server.length > 255
+        || !Number.isSafeInteger(body.round) || body.round < 0
+        || !Number.isSafeInteger(body.players) || body.players < 0) {
+        return json({ ok: false, error: 'Expected round_change, a server name, and nonnegative integer round and players' }, { status: 400 });
+    }
+    const server = getServer(body.server);
+    if (!server || server.destroyed_at) {
+        return json({ ok: false, error: 'Unknown or destroyed server' }, { status: 404 });
+    }
+    const telemetry = {
+        server: body.server as string, round: body.round as number,
+        players: body.players as number, receivedAt: new Date().toISOString()
+    };
+    saveTelemetry(telemetry);
+    emit({ type: 'server-telemetry', entries: [telemetry] });
+    return json({ ok: true, telemetry });
+}
diff --git a/src/routes/servers/[name]/+page.svelte b/src/routes/servers/[name]/+page.svelte
index a6b6e61..2bef5a5 100644
--- a/src/routes/servers/[name]/+page.svelte
+++ b/src/routes/servers/[name]/+page.svelte
@@ -1,4 +1,5 @@
 <script lang="ts">
+    import RoundTelemetry from '$ui/components/RoundTelemetry.svelte';
     import { onMount, onDestroy } from 'svelte';
     import { page } from '$app/stores';
     import { goto } from '$app/navigation';
@@ -304,6 +305,8 @@
                 {/if}
             </div>
 
+            <RoundTelemetry {name} />
+
             {#if destroyError}
                 <div class="destroy-error" role="alert">{destroyError}</div>
             {/if}
diff --git a/tests/unit/telemetry.test.ts b/tests/unit/telemetry.test.ts
new file mode 100644
index 0000000..dff3c7a
--- /dev/null
+++ b/tests/unit/telemetry.test.ts
@@ -0,0 +1,65 @@
+import { afterEach, beforeEach, expect, it, vi } from 'vitest';
+import { newFixture, type Fixture } from '../helpers/fixture.js';
+
+let fixture: Fixture;
+beforeEach(async () => {
+    vi.resetModules();
+    fixture = await newFixture();
+    const { seedServerRegistry } = await import('../../src/lib/server/fleet/servers.js');
+    await seedServerRegistry();
+});
+afterEach(async () => fixture.cleanup());
+
+const payload = { event: 'round_change', server: 't5_zombie_theater_1', round: 17, players: 4 };
+async function post(body: unknown, contentType = 'application/json') {
+    const { POST } = await import('../../src/routes/api/telemetry/+server.js');
+    return POST({ request: new Request('http://localhost/api/telemetry', {
+        method: 'POST', headers: { 'Content-Type': contentType }, body: JSON.stringify(body)
+    }) });
+}
+
+it('persists reports, broadcasts updates, and leaves RCON safety data untouched', async () => {
+    const { subscribe } = await import('../../src/lib/server/pipeline/bus.js');
+    const listener = vi.fn();
+    const unsubscribe = subscribe(listener);
+    expect((await post(payload)).status).toBe(200);
+    expect(listener).toHaveBeenCalledWith(expect.objectContaining({ type: 'server-telemetry' }));
+    unsubscribe();
+    // A new match can legitimately report a lower round; retries overwrite one row.
+    await post({ ...payload, round: 1 });
+    await post({ ...payload, round: 1 });
+    const { closeDb } = await import('../../src/lib/server/db/index.js');
+    closeDb();
+    const { listTelemetry } = await import('../../src/lib/server/fleet/telemetry.js');
+    expect(listTelemetry()).toEqual([expect.objectContaining({ round: 1, players: 4 })]);
+    const { getServer } = await import('../../src/lib/server/fleet/servers.js');
+    expect(getServer(payload.server)?.last_players).toBeNull();
+    const { GET } = await import('../../src/routes/api/events/servers/+server.js');
+    const response = await GET();
+    const reader = response.body!.getReader();
+    await reader.read(); // greeting
+    const snapshot = await reader.read();
+    expect(new TextDecoder().decode(snapshot.value)).toContain('"round":1');
+    await reader.cancel();
+});
+
+it.each([null, [], {}, { ...payload, event: 'other' }, { ...payload, round: -1 },
+    { ...payload, round: 1.5 }, { ...payload, round: '17' }, { ...payload, players: -1 },
+    { ...payload, players: null }])('rejects invalid telemetry: %j', async (body) => {
+    expect((await post(body)).status).toBe(400);
+});
+
+it('rejects unknown and destroyed servers and non-JSON requests', async () => {
+    expect((await post({ ...payload, server: 'unknown' })).status).toBe(404);
+    expect((await post(payload, 'text/plain')).status).toBe(415);
+    const { setServerField } = await import('../../src/lib/server/fleet/servers.js');
+    setServerField(payload.server, 'destroyed_at', new Date().toISOString());
+    expect((await post(payload)).status).toBe(404);
+});
+
+it('rejects malformed JSON', async () => {
+    const { POST } = await import('../../src/routes/api/telemetry/+server.js');
+    expect((await POST({ request: new Request('http://localhost/api/telemetry', {
+        method: 'POST', headers: { 'Content-Type': 'application/json' }, body: '{'
+    }) })).status).toBe(400);
+});