diff --git a/packages/telemetry/src/systemMetrics.ts b/packages/telemetry/src/systemMetrics.ts
index 89f874223..b1b03eb18 100644
--- a/packages/telemetry/src/systemMetrics.ts
+++ b/packages/telemetry/src/systemMetrics.ts
@@ -79,8 +79,7 @@ export class SystemMetricsCollector {
 
     const mem = process.memoryUsage();
     const constrainedMemory = getConstrainedMemoryBytes();
-
-    this.client.track(SYSTEM_METRICS_EVENT, {
+    const properties: TelemetryProperties = {
       process_started_at: this.processStartedAtSeconds,
       process_uptime_ms: Math.round(process.uptime() * 1000),
       rss_bytes: mem.rss,
@@ -88,7 +87,6 @@ export class SystemMetricsCollector {
       heap_total_bytes: mem.heapTotal,
       external_bytes: mem.external,
       array_buffers_bytes: mem.arrayBuffers,
-      constrained_memory_bytes: constrainedMemory,
       cpu_user_us: cpu.user,
       cpu_system_us: cpu.system,
       cpu_elapsed_us: Math.round(elapsedUs),
@@ -96,12 +94,17 @@ export class SystemMetricsCollector {
       free_mem_bytes: freemem(),
       total_mem_bytes: totalmem(),
       cpu_count: cpus().length,
-    });
+    };
+    if (constrainedMemory !== undefined) {
+      properties['constrained_memory_bytes'] = constrainedMemory;
+    }
+
+    this.client.track(SYSTEM_METRICS_EVENT, properties);
   }
 }
 
 function getConstrainedMemoryBytes(): number | undefined {
   if (typeof process.constrainedMemory !== 'function') return undefined;
   const value = process.constrainedMemory();
-  return Number.isFinite(value) ? value : undefined;
+  return Number.isSafeInteger(value) && value >= 0 ? value : undefined;
 }
diff --git a/packages/telemetry/src/types.ts b/packages/telemetry/src/types.ts
index fbdc4485b..2f0974f61 100644
--- a/packages/telemetry/src/types.ts
+++ b/packages/telemetry/src/types.ts
@@ -2,6 +2,8 @@ export type TelemetryPrimitive = boolean | number | string | undefined | null;
 export type TelemetryProperties = Record<string, TelemetryPrimitive>;
 export type TelemetryContext = Record<string, TelemetryPrimitive>;
 
+const MAX_TELEMETRY_NUMBER_MAGNITUDE = Number.MAX_SAFE_INTEGER;
+
 export interface TelemetryEvent {
   readonly event_id: string;
   device_id: string | null;
@@ -27,6 +29,10 @@ export function isTelemetryPrimitive(value: unknown): value is TelemetryPrimitiv
     value === undefined ||
     typeof value === 'boolean' ||
     typeof value === 'string' ||
-    (typeof value === 'number' && Number.isFinite(value))
+    (typeof value === 'number' && isTelemetryNumber(value))
   );
 }
+
+function isTelemetryNumber(value: number): boolean {
+  return Number.isFinite(value) && Math.abs(value) <= MAX_TELEMETRY_NUMBER_MAGNITUDE;
+}
diff --git a/packages/telemetry/test/telemetry.test.ts b/packages/telemetry/test/telemetry.test.ts
index 8e048f635..0eee1b9c6 100644
--- a/packages/telemetry/test/telemetry.test.ts
+++ b/packages/telemetry/test/telemetry.test.ts
@@ -160,6 +160,21 @@ describe('TelemetryClient', () => {
     expect(transport.sent).toHaveLength(0);
   });
 
+  it('drops unsafe numeric properties before enqueueing events', async () => {
+    const client = new TelemetryClient();
+    const transport = new RecordingTransport();
+    client.attachSink(makeSink(transport));
+
+    client.track('big_number', { big: 2 ** 64, keep: true });
+    await client.flush();
+
+    const event = transport.sent[0]?.[0];
+    if (event === undefined) throw new Error('Expected a telemetry event');
+    expect(event.event).toBe('big_number');
+    expect(event.properties).not.toHaveProperty('big');
+    expect(event.properties['keep']).toBe(true);
+  });
+
   it('stops the previous system metrics collector when replacing it', () => {
     const client = new TelemetryClient();
     const first = { stop: vi.fn() };
@@ -267,6 +282,70 @@ describe('SystemMetricsCollector', () => {
     expect(numberProperty(event.properties, 'cpu_count')).toBeGreaterThanOrEqual(1);
   });
 
+  it('omits constrained_memory_bytes when it is not a safe non-negative integer', () => {
+    vi.useFakeTimers();
+    vi.spyOn(process, 'constrainedMemory').mockReturnValue(2 ** 64);
+    const tracked: Array<{
+      event: string;
+      properties: Record<string, number | string | boolean | undefined | null>;
+    }> = [];
+    const client = {
+      track(
+        event: string,
+        properties: Record<string, number | string | boolean | undefined | null> = {},
+      ): void {
+        tracked.push({ event, properties });
+      },
+    };
+    const collector = new SystemMetricsCollector({
+      client,
+      intervalMs: 30_000,
+      warmupSampleMs: 1_500,
+    });
+
+    collector.start();
+    vi.advanceTimersByTime(1_500);
+    collector.stop();
+
+    expect(tracked).toHaveLength(1);
+    const event = tracked[0];
+    if (event === undefined) throw new Error('Expected a system_metrics event');
+    expect(event.event).toBe('system_metrics');
+    expect(event.properties).not.toHaveProperty('constrained_memory_bytes');
+    expect(numberProperty(event.properties, 'rss_bytes')).toBeGreaterThan(0);
+  });
+
+  it('reports constrained_memory_bytes when it is a safe non-negative integer', () => {
+    vi.useFakeTimers();
+    vi.spyOn(process, 'constrainedMemory').mockReturnValue(8 * 1024 ** 3);
+    const tracked: Array<{
+      event: string;
+      properties: Record<string, number | string | boolean | undefined | null>;
+    }> = [];
+    const client = {
+      track(
+        event: string,
+        properties: Record<string, number | string | boolean | undefined | null> = {},
+      ): void {
+        tracked.push({ event, properties });
+      },
+    };
+    const collector = new SystemMetricsCollector({
+      client,
+      intervalMs: 30_000,
+      warmupSampleMs: 1_500,
+    });
+
+    collector.start();
+    vi.advanceTimersByTime(1_500);
+    collector.stop();
+
+    expect(tracked).toHaveLength(1);
+    const event = tracked[0];
+    if (event === undefined) throw new Error('Expected a system_metrics event');
+    expect(event.properties['constrained_memory_bytes']).toBe(8 * 1024 ** 3);
+  });
+
   it('does not duplicate interval sampling when started twice', () => {
     vi.useFakeTimers();
     const tracked: string[] = [];
@@ -363,6 +442,17 @@ describe('payload assembly', () => {
     expect(() => buildPayload([event], 'device-1')).toThrow(/property.nested/);
   });
 
+  it('rejects unsafe numeric property values before outbound send', () => {
+    const event = {
+      ...sampleEvent('bad_number'),
+      properties: {
+        big: 2 ** 64,
+      },
+    };
+
+    expect(() => buildPayload([event], 'device-1')).toThrow(/property.big/);
+  });
+
   it('rejects nested context and array property values before outbound send', () => {
     const nestedContext = {
       ...sampleEvent('bad_context'),