{"type":"excalidraw","version":2,"source":"https://AwesomeSystemDesign.dev","elements":[{"angle":0,"strokeColor":"#6577aa","backgroundColor":"#eef1fc","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-1"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-1"}],"updated":0,"link":null,"locked":false,"id":"shape-0","type":"rectangle","seed":41,"x":16,"y":16,"width":288,"height":93.2,"customData":{"revealStep":1}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-1"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-1","type":"text","seed":114,"x":36,"y":34,"width":248,"height":57.2,"fontSize":22,"fontFamily":1,"text":"user_id | platform |\ntoken","originalText":"user_id | platform |\ntoken","textAlign":"left","verticalAlign":"middle","containerId":"shape-0","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":1}},{"angle":0,"strokeColor":"#6577aa","backgroundColor":"#eef1fc","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-2"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-3"}],"updated":0,"link":null,"locked":false,"id":"shape-2","type":"rectangle","seed":187,"x":16,"y":153.2,"width":288,"height":722.4,"customData":{"revealStep":2}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-2"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-3","type":"text","seed":260,"x":36,"y":171.2,"width":248,"height":686.4,"fontSize":22,"fontFamily":1,"text":"Push Workers\n\n1. Consume from\nKafka push topic\n2. Lookup device\ntokens for user_id\n(from Device Token\nRegistry)\n3. Fan-out to each\ndevice:\n- iOS device → APNs\n- Android device →\nFCM\n- Web browser → Web\nPush API\n4. Handle responses:\n- Success → log\ndelivery\n- InvalidToken →\nremove from registry\n- Throttled →\nbackoff + retry\n- Failure → retry\nqueue (max 3)","originalText":"Push Workers\n\n1. Consume from\nKafka push topic\n2. Lookup device\ntokens for user_id\n(from Device Token\nRegistry)\n3. Fan-out to each\ndevice:\n- iOS device → APNs\n- Android device →\nFCM\n- Web browser → Web\nPush API\n4. Handle responses:\n- Success → log\ndelivery\n- InvalidToken →\nremove from registry\n- Throttled →\nbackoff + retry\n- Failure → retry\nqueue (max 3)","textAlign":"left","verticalAlign":"middle","containerId":"shape-2","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":2}},{"angle":0,"strokeColor":"#a68a53","backgroundColor":"#fff7e6","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-3"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-5"}],"updated":0,"link":null,"locked":false,"id":"shape-4","type":"rectangle","seed":333,"x":16,"y":919.5999999999999,"width":288,"height":779.6,"customData":{"revealStep":3}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-3"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-5","type":"text","seed":406,"x":36,"y":937.5999999999999,"width":248,"height":743.6,"fontSize":22,"fontFamily":1,"text":"Push Notification\nDelivery\n\nDevice Token\nRegistry:\nu123 | ios |\napns_token_abc |\n2026-04-01\nu123 | android |\nfcm_token_xyz |\n2026-04-02\nu123 | web |\nweb_push_key_123 |\n2026-03-28\nu456 | ios |\napns_token_def |\n2026-04-03\n\nOne user can have\nmultiple devices →\nfan-out per user\nAverage: 1.8 devices\nper user\n500M push notifs ×\n1.8 = ~900M actual\nAPNs/FCM calls/day","originalText":"Push Notification\nDelivery\n\nDevice Token\nRegistry:\nu123 | ios |\napns_token_abc |\n2026-04-01\nu123 | android |\nfcm_token_xyz |\n2026-04-02\nu123 | web |\nweb_push_key_123 |\n2026-03-28\nu456 | ios |\napns_token_def |\n2026-04-03\n\nOne user can have\nmultiple devices →\nfan-out per user\nAverage: 1.8 devices\nper user\n500M push notifs ×\n1.8 = ~900M actual\nAPNs/FCM calls/day","textAlign":"left","verticalAlign":"middle","containerId":"shape-4","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":3}}],"appState":{"viewBackgroundColor":"#fbfbf8","gridSize":null},"files":{}}