Phase 10: Determinism Boundary¶

Document Type: Normative Specification
Phase: 10 - Real-Time Subscriptions
Status: Active

The Boundary¶

AeroDB maintains strict determinism through Phase 7. Phase 10 introduces explicit non-determinism for real-time delivery.

┌──────────────────────────────────────────┐
│         DETERMINISTIC ZONE                │
│  WAL → Event Log → Sequence Numbers       │
│  Same input → Same output                 │
└──────────────────────────────────────────┘
                    ║
                    ║ ← DETERMINISM BOUNDARY
                    ║
┌──────────────────────────────────────────┐
│       NON-DETERMINISTIC ZONE              │
│  Dispatcher → WebSocket → Client          │
│  Best-effort, no ordering guarantees      │
└──────────────────────────────────────────┘

What IS Deterministic¶

Component	Guarantee
Event generation	Same WAL → Same events
Sequence numbers	Monotonically increasing
Event content	Immutable once created
Event ordering in log	Matches WAL order

What is NOT Deterministic¶

Component	Why
Delivery timing	Network latency varies
Client receive order	Multiple TCP connections
Reconnection behavior	Client-dependent
Presence state	Eventually consistent

Client Responsibilities¶

Handle out-of-order events using sequence numbers
Implement idempotency for event processing
Support reconnection with resume from last sequence
Tolerate missed events during disconnection

Why This Design?¶

"It is better to be explicitly non-deterministic than to pretend guarantees that don't exist."

Real-time delivery over networks cannot be deterministic. AeroDB acknowledges this honestly.