Reliable Stream Sequence Helpers (protocol/stream-seq.ts)

Pure sequence and gap detection helpers for ordered network streaming protocols. Reuse when implementing custom real-time messaging layers.

// Source: https://github.com/spinabot/brigade | License: MIT | Copyright 2026 Spinabot
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/**
 * Pure sequence helpers for the reliable-streaming layer — shared by the
 * gateway (which STAMPS a per-session seq on every ordered `pi` frame) and the
 * client (which DETECTS a gap to trigger `resume`). Kept pure + dependency-free
 * so both sides agree by construction, and so the logic is unit-testable
 * without booting a socket (the suite convention).
 *
 * The contract in one line: only `pi` frames carry a per-session monotonic
 * `seq`; the client resumes whenever the next seq isn't the contiguous
 * successor of the last one it saw.
 */

/**
 * Next per-session sequence number for a session, or `undefined` when there is
 * no

... (truncated -- full source via MCP)