Add a standalone encoded-packet ring with fixed byte and descriptor arenas for camera/streaming consumers. History mode evicts through the next keyframe, enforcing frame/byte/time bounds without retaining borrowed encoder buffers. Oversized or non-monotonic input is rejected before mutation.
The same arena now offers explicit FIFO operations for delayed output: pushQueued never evicts encoded dependencies, ready checks packet age with overflow-safe subtraction (or EOF flush), and copy/pop let the consumer forward mature packets. Full FIFO input fails without mutation. cloneFrom creates a minimally sized independent suffix for an asynchronous snapshot worker; it handles wrapped bytes and cleans up partial allocations. The module creates no threads or filesystem work. Export and document the module without changing existing buffered output code.
Validation: five focused tests pass on Zig 0.15.2 and Home's current development toolchain, covering GOP eviction, byte wrap, frame/time/byte limits, FIFO maturity/EOF/backpressure and clone allocation failures. Targeted pickier passes. zig-camera integration independently decodes H.264/HEVC delayed clips and frozen snapshots, checks frame ordering and sample-synchronized AAC/PCM, and tests stop/close/reopen behavior. No FFmpeg/Libav dependency is introduced; hardware throughput remains unmeasured.