Interactive Second-Screen Live Broadcast Web Client Architecture Spec
Architect a real-time synchronized live event companion web client with high-concurrency websocket management and zero-lag DOM updates.
Use this template when planning companion web apps for live sports, awards shows, or esports broadcasts. It delivers a comprehensive specification covering high-throughput event synchronization, optimistic UI state, and graceful degradation under traffic surges.
Role: Staff Real-Time Web Platform Engineer specializing in high-concurrency event-driven web applications and interactive second-screen entertainment experiences.
Context
- Broadcast event category: {{broadcast_event_type}}
- Concurrent connected client peak: {{peak_concurrent_users}}
- Video-to-client sync mechanism: {{sync_mechanism}}
- Client state management engine: {{state_management_library}}
- Automated chat/reaction moderation: {{chat_moderation_service}}
- Edge distribution network: {{edge_cdn_vendor}}
Task
Generate a technical specification for an interactive second-screen web client that synchronizes real-time polls, live commentary, and fan reactions with high-volume live video feeds.
Method
- Define WebSocket connection lifecycle, reconnection backoff with jitter, and heartbeat policies on {{edge_cdn_vendor}}.
- Establish state synchronization protocols aligning client interactions with playhead timestamps via {{sync_mechanism}}.
- Design high-frequency message batching and requestAnimationFrame rendering throttles inside {{state_management_library}}.
- Detail the optimistic mutation pipeline for user polling, trivia submissions, and reaction bursts.
- Outline client-side integration and pre-filtering pipelines connecting to {{chat_moderation_service}}.
- Formulate progressive degradation stages triggered during {{peak_concurrent_users}} traffic spikes to protect core UI thread responsiveness.
- Detail local storage caching and state rehydration mechanics for unexpected tab refreshes during {{broadcast_event_type}}.
Constraints
- MUST maintain steady 60fps UI rendering during bursts exceeding 1,000 incoming messages per second.
- MUST NOT allow unmoderated WebSocket payloads to render raw innerHTML without sanitization.
- Memory footprint on mobile browser runtimes must remain below 120MB across multi-hour sessions.
- Offline and reconnecting states must provide deterministic visual indicators without locking interactive inputs.
Output format
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- System Topology & Connection Protocol Spec
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- Broadcast Timecode Synchronization Strategy
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- State Management & Batching Contract
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- Moderation & Content Sanitization Pipeline
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- Traffic Surge Degradation Matrix (Tier 1 to Tier 4)
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- Message Wire Protocol (JSON / Binary Payload Schemas) Total length: 850 to 1300 words.
Self-review
- Ensure {{peak_concurrent_users}} and {{edge_cdn_vendor}} scaling constraints are fully accommodated in the connection topology.
- Validate that {{sync_mechanism}} provides specific fallback when broadcast audio/video timecodes drift.
- Confirm message deduplication logic covers network packet retransmissions.
Explicit role, a named task, and discrete steps the model can follow.
Background, inputs and variables the model needs before it starts.
Hard boundaries — what the model must and must not do.
A named, field-level shape for the response.
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Length and structure that travel across frontier models.
Signal density — instruction weight without padding.
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