Support player ping in game telemetry

docs/beta-test-plans.md

@@ -33,6 +33,14 @@ there are no players. Names and GUIDs are strings; keep GUIDs as strings to
 preserve their precision. Round and stat values are nonnegative JSON integers.
 Each GUID must appear only once within a report's player array.
 
+Every event also accepts an optional per-player `ping`: the game server's current
+latency measurement in milliseconds, as a nonnegative JSON integer (for example,
+`"ping": 42`). Send `null` or omit the field when unavailable; do not substitute
+zero for a missing measurement. Older reporters without this field remain valid.
+Fleet displays ping from the same telemetry snapshot as the player roster and
+scores, with `—` for unknown values. Ping is retained and streamed with the latest
+report; it does not contribute to leaderboard statistics.
+
 ### Game start
 
 Send when the game starts. Round and stats are not required.

src/lib/server-observation.ts

@@ -70,7 +70,7 @@ export function selectServerObservation<T extends ServerObservation>(server: T,
         return { ...result, health: 'online', status_source: 'telemetry', last_players: players,
             last_map: report.map, last_seen_at: report.receivedAt, last_error: null,
             roster: report.players.map(player => ({ num: null, score: 'score' in player ? player.score : null,
-                ping: null, guid: player.guid, name: player.name })),
+                ping: player.ping ?? null, guid: player.guid, name: player.name })),
             active_since: players > 0 ? timing.activeSince : null,
             inactive_since: players === 0 ? timing.inactiveSince : null,
             game_started_at: players === 0 ? null : timing.gameStartedAt,

src/lib/telemetry.ts

@@ -1,6 +1,8 @@
 export interface TelemetryPlayer {
     name: string;
     guid: string;
+    /** Server-measured latency in milliseconds; absent/null when unavailable. */
+    ping?: number | null;
 }
 
 export interface TelemetryPlayerStats extends TelemetryPlayer {
@@ -51,7 +53,13 @@ export function parseGameEvent(value: unknown): GameEvent {
         for (const key of ['name', 'guid'] as const) {
             if (typeof player[key] !== 'string' || !player[key].trim()) throw new Error(`players[${index}].${key} must be a nonempty string`);
         }
-        const identity = { name: player.name as string, guid: player.guid as string };
+        const identity: TelemetryPlayer = { name: player.name as string, guid: player.guid as string };
+        if (player.ping !== undefined) {
+            if (player.ping !== null && (!Number.isSafeInteger(player.ping) || (player.ping as number) < 0)) {
+                throw new Error(`players[${index}].ping must be a nonnegative integer or null`);
+            }
+            identity.ping = player.ping as number | null;
+        }
         if (guids.has(identity.guid)) throw new Error(`players[${index}].guid must be unique within the report`);
         guids.add(identity.guid);
         if (body.event === 'game_start') return identity;

tests/unit/server-observation.test.ts

@@ -56,6 +56,17 @@ describe('shared server observation', () => {
         expect(fallback).toMatchObject({ status_source: 'rcon', health: 'online', last_players: 4, last_seen_at: at(40_000) });
     });
 
+    it('displays telemetry pings and clears missing readings on subsequent reports', () => {
+        const telemetry = report(0, 4);
+        telemetry.players = telemetry.players.map((player, i) => ({ ...player, ping: [0, 42, 999, null][i] }));
+        const selected = selectServerObservation(server(), telemetry, now);
+        expect(selected.roster?.map(player => player.ping)).toEqual([0, 42, 999, null]);
+        expect(selectServerObservation(selected, report(1, 4), now + 1).roster?.map(player => player.ping)).toEqual([null, null, null, null]);
+        const start = { ...gameEvent('game_start', 0, 1, 'managed'), event: 'game_start' as const, receivedAt: at(),
+            players: [{ name: 'Player 1', guid: '123', ping: 25 }] };
+        expect(selectServerObservation(server(), start, now).roster?.[0]).toMatchObject({ score: null, ping: 25 });
+    });
+
     it.each(['starting', 'restarting', 'unhealthy', 'exited'])('telemetry cannot override container state %s', state => {
         const selected = selectServerObservation(server({ health: state === 'starting' || state === 'restarting' ? 'starting' : 'offline', container_state: state }), report(), now);
         expect(selected.health).not.toBe('online');

tests/unit/server-status.test.ts

@@ -494,7 +494,9 @@ describe('database fleet and container readiness', () => {
         const { subscribe } = await import('../../src/lib/server/pipeline/bus.js');
         db.prepare("UPDATE servers SET last_players = 4, last_seen_at = ? WHERE name = 'managed'").run(new Date().toISOString());
         inspect.mockResolvedValue({ ok: true, state: 'running' });
-        await postTelemetry(gameEvent('heartbeat', 15, 3, 'managed'));
+        const telemetry = gameEvent('heartbeat', 15, 3, 'managed');
+        telemetry.players[0].ping = 42;
+        await postTelemetry(telemetry);
         const events: unknown[] = [];
         const unsubscribe = subscribe(event => events.push(event));
         try { await fanoutStatus(); } finally { unsubscribe(); }
@@ -503,7 +505,8 @@ describe('database fleet and container readiness', () => {
         expect(server).toMatchObject({ health: 'online', last_players: 3, status_source: 'telemetry', last_error: null,
             rcon_status: { last_players: 4, last_error: 'timeout:old process' } });
         expect(server.roster).toHaveLength(3);
-        expect(server.roster[0]).toMatchObject({ ping: null, score: 5000 });
+        expect(server.roster[0]).toMatchObject({ ping: 42, score: 5000 });
+        expect(server.roster[1].ping).toBeNull();
         expect(events).toContainEqual(expect.objectContaining({ type: 'server-status', entries: [expect.objectContaining({
             health: 'online', players: 3, roster: server.roster, lastSeenAt: server.last_seen_at
         })] }));

tests/unit/telemetry.test.ts

@@ -180,6 +180,33 @@ it('accepts all four events without an active beta and updates match lifecycle',
     expect((await post(gameEvent('game_end', 0, 0))).status).toBe(200);
 });
 
+it.each(['game_start', 'round_change', 'heartbeat', 'game_end'] as const)('preserves %s player pings through ingestion, streaming and reload', async event => {
+    const payload = gameEvent(event, 17);
+    payload.players = payload.players.map((player, i) => ({ ...player, ping: [0, 42, 999, null][i] }));
+    const { subscribe } = await import('../../src/lib/server/pipeline/bus.js');
+    const listener = vi.fn();
+    const unsubscribe = subscribe(listener);
+    try {
+        const response = await post(payload);
+        expect(response.status).toBe(200);
+        expect((await response.json()).telemetry.players).toEqual(payload.players);
+        expect(listener).toHaveBeenCalledWith({ type: 'server-telemetry', entries: [expect.objectContaining({ players: payload.players })] });
+        const { closeDb } = await import('../../src/lib/server/db/index.js');
+        closeDb();
+        const { listTelemetry } = await import('../../src/lib/server/fleet/telemetry.js');
+        const { telemetryReport } = await import('../../src/lib/server/fleet/status-evidence.js');
+        expect(listTelemetry()[0].players).toEqual(payload.players);
+        expect(telemetryReport(payload.server)?.players).toEqual(payload.players);
+    } finally { unsubscribe(); }
+});
+
+it.each([-1, 1.5, '42', false, {}, [], Number.MAX_SAFE_INTEGER + 1])('rejects invalid player ping: %j', async ping => {
+    for (const event of ['game_start', 'heartbeat'] as const) {
+        const body = gameEvent(event, 17, 1);
+        expect((await post({ ...body, players: [{ ...body.players[0], ping }] })).status).toBe(400);
+    }
+});
+
 it.each([null, [], {}, ...['boot', 'session_start', 'match_end', 'feature', 'other'].map(event => ({ ...payload, event })),
     { ...payload, map: '' }, { ...payload, map: undefined }, { ...payload, round: -1 },
     { ...payload, round: 1.5 }, { ...payload, round: '17' }, { ...payload, players: 4 }, { ...payload, players: null },