feat(net): N6 - ConnectResponse retransmit + fragment assembler eviction

Campaign N Slice N6, the final implementation slice.

ConnectResponse handshake retransmit:
- While the connection is unconfirmed, the Connect character-list pump
  resends the IDENTICAL cleartext ConnectResponse (same sequence 1, same
  cookie, the one encoded datagram - no new outbound state) on retail's
  strict 0.333333333 s gate. Retail: ClientNet::ProcessConnection
  @ 0x00545450, case cs_ConnectionRequestAcked @ 0x0054547B (the constant
  load at 0x00545481; the mask-0x41 strictly-greater x87 test at
  0x0054548C); ClientNet::SendConnectAck @ 0x005440F0 re-stamps
  lastSentHandshake_ (0x00544102) and rebuilds the same cookie packet.
- Confirmation = the first checksum-valid post-negotiation packet whose
  header lacks the ConnectRequest flag: retail's cs_ConnectionRequestAcked
  -> cs_Connected edge (ClientNet::ProcessPacket @ 0x00545100, the 0x40000
  exclusion at 0x0054514E, SetConnectionState(..., 5) at 0x00545160).
- The cadence rides the TransportClock (virtual-clock testable through
  TransportClockSource); the Connect deadline stays wall-clock.
- ACE safety pinned against the N0 model: a duplicate while still
  AuthConnectResponse re-routes idempotently through NetworkManager's
  pre-route; after acceptance CheckState clause 2 drops it pre-CRC at
  zero keystream cost.
- Pre-N6, one lost ConnectResponse was a hang to the Connect deadline;
  the N5 decorator deliberately arms after this window, so nothing
  covered it.

FragmentAssembler eviction (divergence register row AD-52):
- Partials evict 60 s after their last ACCEPTED fragment; the stamp
  refreshes on every new fragment (retail's re-stamp rule,
  ArrivedEphInfo::UpdateNetBlobID @ 0x0054AE00), so a merely-slow partial
  can never age out - 60 s is a floor, not a tunable. Swept from
  ReliableTransport.Sweep on retail's 5 s flush cadence
  (Indicator::FlushTimedOutEphInfo @ 0x0054A3D0, the gate at 0x0054A3DC;
  per-entry ArrivedEphInfo::fTimedOut @ 0x0054AE30). N4's RejectRetransmit
  abandonment made an unrecoverable partial a REACHABLE permanent state;
  the TTL reclaims it.
- A 64-entry completed-sequence ring drops late duplicate fragments of
  already-completed messages instead of allocating a fresh partial that
  can never complete (the completed-then-duplicate leak).

Fold-ins:
- N5 review LOW-5: NetProbeTests + LossyTransportDecoratorTests (the
  static NetDiagnostics / Console.SetOut mutators) share one
  DisableParallelization xunit collection so they never run alongside
  classes constructing WorldSession.
- Campaign section 9: N6 ledger row recorded; N5 row verified carrying
  4e290f00.

Gates: 757 Core.Net Release tests green (10 new); full solution Release
green (0 failures / 5 skips); connected lifecycle gate PASS; the
N5-strengthened connected loss gate PASS on its first live run (2%/seed 1:
dropped out=3 in=10, resends=1 nak-in=1 nak-out=5, cksum-fail=0
sanity-drop=0 uncached-nak=0).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/plans/2026-07-29-network-transport-campaign.md

@@ -257,4 +257,4 @@ verbatim in each implementer prompt.
 | N3 | complete | `0265cc42` — Opus review PASS (advisories folded into N4: transitional-state wording, SharedInit citation, pump-order wording, control-packet Time/Iteration rule, stale budget-break comment) | AckNakScheduler + 2.0 s cumulative ack (`Transport/AckNakScheduler`): ONE shared timestamp (`ReceiverData::timeStamp_` @ +0x10) arbitrating NAK-xor-ack per sweep (`ClientNet::ProcessConnection @ 0x00545450`); the ack is one cleartext exact-flags `AckSequence` carrying the tracker's `highestIDReceived_` behind the >= 2.0 s gate (`SharedNet::EnqueuePak @ 0x00543B10` — the binary's only 0x4000 construction site), armed at connection birth (`ReceiverData::Init @ 0x00548EF0`). The Phase 4.9 per-packet reflex ack and `WorldSession.SendAck` are DELETED; the `[net-tick]` acks/s probe now reads `Stats.AcksSent`. Sweep order per `FlowQueue::Empty @ 0x00548A20`: interval clock, NAK/ack arbitration, pending resends, prune. **N3 transitional state (closed by N4):** a non-empty NAK set suppressed the ack and emitted NOTHING — the exposure was real even on loopback, just low-probability: one receive-buffer drop parks an id, every later sweep takes the silent NAK branch, acks stop (witness: `[net-tick] acks/s=0`), and ACE disconnects the quiet session at its 60 s timeout. N4 completed the branch. **N1 advisory retired (fold-in):** fresh reliable sends now stamp `Header.Time` = the current interval id (`FlowQueue::TransmitNewPackets @ 0x00547A60`, header build at 0x00547A84); ACE ignores inbound `Header.Time`, so the wire is unaffected. New `WorldSession.TransportClockSource` seam drives the gate on virtual time. 723 Core.Net tests green (keepalive property proven: a quiet session's 2 s acks refresh ACE's 60 s deadline across a 120 s virtual horizon; storm collapse: a 50-packet flood → ONE ack; the model accepts the reused-sequence ack without advancing its watermark). Connected lifecycle + canonical nine-stop gates PASS. |
 | N4 | complete | `852a59e3` — **Opus review PASS** (reclaim invariant attacked from five angles, held; NAK fidelity verified to the x87 masks; AP-125 filed + F1 false-arithmetic wording + F5 ordinal sentinel fixed in the acceptance commit; F3 Iteration-on-fresh-sends folds into N5) | Client NAK emission + RejectRetransmit consumption. `AckNakScheduler` completes the NAK branch: one cleartext exact-flags `RequestRetransmit` per sweep behind the STRICT 0.6 s gate on the ONE shared timestamp (`SharedNet::EnqueueNaks @ 0x00543BD0` — the 0x41-mask x87 test at 0x00543C03 proceeds only on strictly-greater, contrast the ack's >=), body u32 count + ids ascending capped at 114 (`ReceiverData::GetNaks @ 0x005490C0`, cap 0x72), borrowed sequence, never an ack in a NAK sweep. Control-header rule decided for BOTH emissions: `Time` = interval id, `Iteration` = session iteration, per the shared retail header build (`FlowQueue::TransmitNewPackets @ 0x00547A60` @ 0x00547A84); ACE reads neither. THE design piece: the AD-51 reclaimed-word pool in `InboundSequenceTracker` closes the ACE cleartext-reject keystream hazard the N2 ledger row recorded — ACE's `RejectRetransmit` consumes a fresh cleartext sequence with NO keystream word, so the gap walk mis-parks a word for it and the whole inbound stream runs one word ahead. On a VALIDATED cleartext reject (`WorldSession` calls `OnCleartextRejectSequence` post-checksum), the tracker removes the mis-park, bubble-shifts every later-drawn parked word down one position (per-word draw ordinals; ascending id ⇔ ascending draw order), and pools the excess for the next fresh draws, consumed lowest-draw-order-first — exact for any number of interleaved rejects in any arrival order (a plain FIFO is NOT: reject-after-higher-arrival crosses the parked chain, and dual out-of-order rejects pool out of draw order — both pinned by tests). Reject BODY ids keep N2's discard (word-bearing server-side, consumed-in-place). N3 advisories all folded: honest transitional wording (above), `ReceiverData::SharedInit @ 0x00548EF0` (from `Init @ 0x00548FA0`) citation, `FlowQueue::Empty` pump-order comment (TransmitNaks → TransmitAcks → TransmitNewPackets, interval increment LAST @ 0x00548A9D; our clock-first order is cosmetic vs ACE), the Time/Iteration rule, and the stale `WorldSession` budget-break comment. Gate arithmetic hardened: gate ticks now round (0.6 has no exact double; truncation opened the strict gate AT the boundary). 737 Core.Net tests green, including: strict-gate boundary, shared-timestamp both directions, NAK-suppresses-ack, full wire-shape + 114-cap pins, model-served retransmission round trip, five tracker reclaim proofs, the 130-s virtual prune → fresh-sequence reject system test (victim abandoned, later traffic decodes, pool drains to zero), 10 s long-loss (NAKs on the gate cadence, zero acks, heal inside the window), and the capstone soak: 2% seeded bidirectional loss × 10,000 messages → zero message loss both ways, ACE crypto headroom 256 at convergence with a ≥250 no-erosion floor mid-flight, NAK set / reclaim pool / pending resends / ACE out-of-order buffer all zero, cache at the single watermark entry (retail Flush prunes STRICTLY below the ack). Soak notes: ACE never NAKs a quiet client (§3 row 1), so convergence keeps a C2S trickle flowing — a real idle-client tail loss heals only on the next action, an ACE constraint outside N4's scope. |
 | N5 | complete | `4e290f00` — **Opus review PASS** (structural absence + arming gate + un-gameability + teardown all verified; ledger arithmetic reconciled). Acceptance folded in the review's gate strengthenings: per-direction recovery conjunction + the three keystream-health invariants (cksum-fail/sanity-drop/uncached-nak == 0) + the EnterWorldBody unrecoverable-tail caveat. Revert: `git revert 4e290f00d86ebd320d2da609fd7cd15d7175c4f0`. Test-collection hygiene (static NetDiagnostics mutation) folds into N6 | Loss observability + the LossyTransportDecorator + the connected loss gate — the permanent removal of the loopback blindness (§1). `[net-tick]` gains `resend/s nak-out/s nak-in/s rej-in/s dup-drop/s parked/s reclaim/s cache= nakset=` (window deltas mirroring acks/s; `TransportStats` gains `RejectsReceived`; string work probe-gated, counters unconditional) and `WorldSession.Dispose` emits one cumulative `[net-final]` totals line so the gate asserts exact counters, not rounded rates. N4-review F3 folded: fresh reliable sends stamp `Iteration` = the session iteration through the same shared retail header build already cited for `Time` and the N4 control packets (`FlowQueue::TransmitNewPackets @ 0x00547A60`, the build at 0x00547A84/0x00547AA8) — the control-header rule now holds across all three send shapes; ACE reads neither field inbound. `Transport/LossyTransportDecorator`: deterministic seeded per-direction loss (`ACDREAM_NET_DROP_PCT`/`_SEED`/`_DIR` via `NetDiagnostics` typed properties, Rule 5), armed only after the first ENCRYPTED outbound datagram is forwarded (parse-free flags-word check — the cleartext handshake always survives; handshake loss belongs to N6), structurally absent at 0% (`WrapIfConfigured` returns the raw transport; the default factory is the only production seam). The logoff-confirmation wait now runs the transport sweep — retail's pump (`Client::UseTime @ 0x00411C40`) never stops before `LogOffServer`, and the loss gate exposed that a dropped S2C confirmation was gap-detected but never NAKed during `Dispose`. `tools/run-connected-loss-gate.ps1` (default 2%/seed 1) runs the standard lifecycle route through the decorator vs local ACE and FAILS unless `[net-final]` shows resends>0 OR nak-out>0 OR nak-in>0 AND the decorator's own dropped ledger is non-zero — a loss gate that never dropped proves nothing, asserted explicitly. The lifecycle gate defensively clears the drop vars (decorator-absent baseline). **First loss-observing gate evidence (2026-07-29, 2%/seed 1, local ACE):** decorator dropped out=3 in=10 of forwarded out=183 in=496; `[net-final] resends=2 nak-in=2 nak-out=6 rej-in=0 acks-out=114 acks-in=119 dup-drop=0 sanity-drop=0 cksum-fail=0 parked=9 reclaimed=0 uncached-nak=0 cache=1 nakset=0` — both recovery directions fired on a real connected route (ACE NAK → cached resend; client gap-walk park → NAK → ACE retransmit), all six checkpoints validated, graceful logout confirmed, ACE recorded the transport Disconnect, RESULT=PASS. The gate immediately paid for itself: it exposed that the Dispose logoff-confirmation wait processed inbound but never swept the transport, so a lost S2C confirmation could be gap-detected yet never NAKed — fixed by running the sweep in that third blocking pump (retail's `Client::UseTime @ 0x00411C40` pump runs until `LogOffServer`). Known tail caveat recorded in the gate header: a drop landing on the single-shot logoff request or transport Disconnect (~pct each) is unrecoverable by ACE's arrival-driven NAK design (§3 row 1) — rerun with another seed, never widen teardown tolerances. #261 filed for `LinkStatusSnapshot.PacketLossPercentage` (retail `CLinkStatusAverages` formula required; inventing a ratio forbidden). 747 Core.Net tests green (decorator determinism/direction/arming/structural-absence, the 5% seeded WorldSession lossy lifecycle with zero message loss + Headroom 256, `[net-tick]` field pins, Iteration-stamp pins). |
-| N6 | pending | — | |
+| N6 | complete | SHA recorded at closeout | ConnectResponse handshake retransmit + fragment-assembler eviction — the final implementation slice. **Retransmit:** while unconfirmed, the Connect character-list pump resends the IDENTICAL cleartext ConnectResponse (same sequence 1, same cookie, the one encoded datagram — no new outbound state) on retail's strict 0.333333333 s gate (`ClientNet::ProcessConnection @ 0x00545450` case `cs_ConnectionRequestAcked` at 0x0054547B, the constant at 0x00545481, the mask-0x41 strictly-greater test at 0x0054548C; `ClientNet::SendConnectAck @ 0x005440F0` re-stamps `lastSentHandshake_` at 0x00544102 and rebuilds the same cookie packet). Confirmation = the first checksum-valid post-negotiation packet without the ConnectRequest flag, retail's `cs_ConnectionRequestAcked → cs_Connected` edge (`ClientNet::ProcessPacket @ 0x00545100`: the 0x40000 exclusion at 0x0054514E, `SetConnectionState(..., 5)` at 0x00545160). The cadence rides the TransportClock (virtual-clock testable via `TransportClockSource`); the Connect deadline stays wall-clock. ACE-safety pinned against the N0 model: a duplicate while still `AuthConnectResponse` re-routes idempotently through NetworkManager's pre-route; after acceptance `CheckState` clause 2 drops it pre-CRC at zero keystream cost. Pre-N6 a lost ConnectResponse was a hang to the Connect deadline — routine on a real path, and the N5 decorator deliberately arms after this window, so nothing covered it. **Assembler eviction (AD-52):** partials evict 60 s after their last accepted fragment (re-stamp-on-update per retail `ArrivedEphInfo::UpdateNetBlobID @ 0x0054AE00`), swept from `ReliableTransport.Sweep` on retail's 5 s flush cadence (`Indicator::FlushTimedOutEphInfo @ 0x0054A3D0`, gate at 0x0054A3DC; per-entry `fTimedOut @ 0x0054AE30`) — N4's RejectRetransmit abandonment had made an unrecoverable partial a reachable permanent state. A 64-entry completed-sequence ring drops late duplicates of already-completed messages instead of re-partialing them (the completed-then-duplicate leak). 60 s is a floor, never a tunable to shrink. **Fold-ins:** N5-review LOW-5 — `NetProbeTests` + `LossyTransportDecoratorTests` (the static-`NetDiagnostics`/`Console.SetOut` mutators) share one `DisableParallelization` xunit collection so they never run alongside classes constructing `WorldSession`. 757 Core.Net tests green (drop-first-ConnectResponse-retry-heals with exactly one retry and none after confirmation; clean handshake sends exactly one; server-responses-lost retries drop harmlessly at the model while the N2/N4 gap-walk → NAK → cached-retransmit path heals the handshake responses; model-level duplicate-after-acceptance CheckState pin; assembler TTL floor boundary/refresh-on-update/ring-drop/ring-bound; transport-level sweep eviction). Connected lifecycle gate PASS (capped six-checkpoint route + uncapped reconnect, graceful exits, zero failures). The N5-STRENGTHENED loss gate PASS on its first live run (2%/seed 1, local ACE): decorator `[net-loss] dropped out=3 in=10 forwarded out=181 in=496 armed=True`; `[net-final] resends=1 nak-in=1 nak-out=5 rej-in=0 acks-out=114 acks-in=116 dup-drop=0 sanity-drop=0 cksum-fail=0 parked=8 reclaimed=0 uncached-nak=0 cache=1 nakset=0` — the per-direction recovery conjunction held (C2S: resends+nak-in > 0; S2C: nak-out > 0), all three keystream-health invariants zero, ledger converged at the single watermark cache entry. |