forked from unom/punktfunk
enricobuehler
290d760ea4
Phase 0 of mid-session shard-payload renegotiation (planning design/shard-payload-reneg.md), stacked on the leg-1 MTU resilience. All three legs are client-side and forward-compatible: deployed clients that carry them accept a mid-session shard change the moment a future host sends one, and nothing changes on the wire until then. - W0.1 — the reassembler's strict shard_bytes firewall becomes per-frame pinning: a frame's first-arriving packet pins that frame's shard size (bounds-checked to [min_shard_bytes, max_shard_bytes], even), later packets must match the pin, and the per-frame block ceiling derives from the pinned size (a session-level cap would reject legitimate post-shrink frames). The reorder race between an ordered control message and unordered video dies structurally: old-geometry frames in flight complete under their own pin while new frames arrive under the new one, and no cross-geometry splice can land in one buffer. The in-flight budget stays byte-based and exact. - W0.2 — MAX_DATAGRAM_BYTES 2048 → 9216: every receive path (transport RECV_BUF, the recvmmsg ring) now accepts sealed jumbo datagrams (9000-MTU LAN ≈ 8908-byte shards). Static buffers over resize-on-ack: the ring delta is 128 × ~7 KiB ≈ 896 KiB per client session, lazily allocated, hosts unaffected. Grep verdict: no embedder uses the constant directly, so no C ABI bump — the regenerated header rides along (drift gate). - W0.3 — trailing Hello field max_shard_payload: u16 (0/absent = legacy), the append-with-placeholder discipline of video_caps/ client_caps. One field is both the renegotiation capability flag and the jumbo ceiling; core's pump advertises it for all client families, the probe too. - Host seam for Phase 1, dead until wired: Packetizer::set_shard_payload (re-derives the block ceilings; construction delegates to it) + Session::set_shard_payload (host-only, Config::validate parity). Verification (the 0.23.0 lesson — geometry changes breed sizing bugs): the slice-wire suite re-runs at shard 512/1216/1408/8908 (exact-multiple sweep, lossy + reversed roundtrips, sentinel path, in-flight budget); mid-stream shrink→grow→revert delivery; the old-geometry reorder race; cross-geometry splice rejection; firewall bounds non-vacuous both ways; a 48-case mixed-geometry reorder-torture proptest asserting per-frame byte-identical DELIVERY and an exactly-zero final budget; and a sealed loopback session test (continuous crypto/replay) delivering frames across live re-keys — every test asserts delivered frames, never the absence of errors. core: 294/294 --features quic + clippy -D warnings (macOS), fmt.