A second adversarial review of the previous fix commit found two of its
nine fixes silently defeated each other: the seq-range guard (fix for a
MEDIUM epoch-mismatch finding) capped the exact variable the ring-overflow
resync (fix for the original CRITICAL finding) depends on, making the
resync unreachable in production and recreating permanent input death at
a lower failure threshold, reachable via ordinary server tick loss alone.
- CRITICAL: rebind the seq-range guard to InputJitterBuffer's own
highest_ingested_seq (now public) instead of the consumer-side
last_applied_seq, so it tracks the client's send epoch rather than a
value that can lag arbitrarily far behind during a stall.
- HIGH: InputLeadController's release logic still ANDed the old
`lead > LEAD_MIN` gate onto the new depth-driven condition, so a
backlog the controller never caused still couldn't drain. Split into
two independent decisions: the seq-duplicate action follows real
depth alone; lead's own bookkeeping separately never drops below its
floor.
- MEDIUM: widen the CI driver's movement/stalled sampling margin
(run_seconds - 2.0, was - 0.5) and assert the peer is still in
multiplayer.get_peers() at sample time, since the old margin let the
check pass on residual starvation grace after a bot had already
disconnected.
- LOW: measure horizontal-only displacement in the human smoke test's
movement check — the old 3D-distance bar was beatable by pure
gravity settling with fully dead input.
- LOW: fix a real "clean stderr" violation (match_net.gd broadcasting
a departure notice to a peer whose ENet channels are already torn
down, including a second peer disconnecting in the same poll batch)
by deferring the notification to the next idle frame.
- Wire the server's per-slot stalled bit into the client debug overlay
for real — a prior commit message claimed this already reached the
overlay when only the CI gate actually read it.
Re-verified end-to-end against the real production RPC path (not just
unit tests in isolation, which is how the composition bug got past the
first round): a 2-bot CI match with a 1.5s host SIGSTOP freeze injected
mid-run, well past the 0.6s threshold the review reproduced the bug at,
now recovers cleanly on repeated runs with zero stderr noise.
An Opus subagent's adversarial review of Phase 3 found a critical, silent,
permanent bug plus eight smaller real issues, all empirically verified
with real two- and three-process runs:
CRITICAL: InputJitterBuffer's 32-entry ring permanently bricked a
player's input once the un-consumed backlog exceeded the ring's
capacity - a fresh arrival would land in the exact slot consume() was
still waiting on, and since both counters only ever advance, the gap
never closed. Reproduced with a real SIGSTOP/SIGCONT host freeze:
client movement dropped from ~26m to 0.00m at ~0.7s, worse under real
loss (a lossy link lowered the fatal threshold to ~400ms), and
reachable via ordinary clock drift with no external trigger at all.
Fixed by tracking the highest seq ever ingested and having consume()
jump directly to what the ring can still provide once the gap exceeds
capacity, instead of starving through an unrecoverable span. Re-verified
with a 3s freeze (well past the original threshold): full recovery.
HIGH: InputLeadController's release logic was gated on its own past
attacks (lead > LEAD_MIN) rather than the real server-reported depth, so
a backlog it didn't itself cause was never drained. Fixed to gate on
actual depth vs target.
MEDIUM-HIGH: the rate limiter's "N consecutive over-budget seconds"
streak hard-reset to 0 on any clean window, letting a duty-cycled flood
(burst, one clean window, repeat) sustain ~33x budget indefinitely with
zero warnings. Replaced with a leaky-bucket accumulator immune to the
same evasion by construction.
MEDIUM: the seq > server_tick + 20 guard compared two unrelated clock
epochs (server process uptime vs. client's own from-zero seq numbering),
so it never actually protected anything on a long-running server and
could silently drop an honest client's input forever. Bound against the
buffer's own last_applied_seq instead.
MEDIUM: InputJitterBuffer.stalled was computed but never reached the
wire - the one signal that would have made the ring-overflow bug visible
anywhere. Now wired through _ship_to_net_body_state.
MEDIUM: task 3.6's CI driver's assertions didn't depend on client input
reaching the server at all, so it kept passing with the ring-overflow
bug actively triggered. Added real ship-movement and non-stalled checks,
sampled while bots are still connected (an initial attempt sampled after
their own legitimate disconnect, which starves identically to the bug).
LOW-MEDIUM: a lead change silently mislabelled _input_history's older
entries, since the wire format has no per-entry seq field. Fixed by
handling each delta case (ordinary/release/attack) on its own terms.
LOW: bandwidth and snapshot-loss overlay metrics froze at their last
value during a total outage instead of decaying - exactly when they
matter most. Both now report honest post-outage values.
LOW: a guard comment on NetworkManager._ping misdescribed the actual
disconnect_peer() arguments in use. Corrected.
New permanent regression tests: test_ring_overflow_resyncs_to_fresh_data
_instead_of_starving_forever, test_release_drains_a_backlog_it_never_
caused_itself, and client-abuse-flood-dutycycle (reproduces the exact
duty-cycle evasion). Full regression suite, including the net-sim-latency
milestone gate, all abuse roles, and the CI driver, re-run clean after
every fix.
Extends net_debug_overlay.gd (Phase 1's RTT/offset display) with the
rest of task 3.7's list: jitter (new RFC3550-style EWMA in
NetworkManager, computed from raw per-sample RTT before Phase 1's own
min-filtering, since that filter is deliberately jitter-insensitive by
design), input buffer depth and input_lead (both already tracked
client-side for task 3.3), snapshot loss (a new EWMA in networked_match.gd
over each received snapshot's own server_tick gap - snapshots go out at a
steady one-tick cadence, so a gap is direct evidence of a drop or
reorder), snapshot age (computed on demand from the same bias-corrected
tick estimate the interpolator itself uses), and bandwidth (new rolling
per-second byte counters in MatchSim, on the two 60Hz hot-path channels
only). Prediction error is deliberately omitted with a comment explaining
why: there's no client-side prediction to measure until Phase 4.
Verified values are live and plausible, not just present, by calling
get_net_debug_stats() directly in a real two-process test and checking
the numbers make sense: bandwidth matched the wire format's own byte
math almost exactly (measured ~2400 B/s sent against a computed 40B x
60Hz, ~3540 B/s received against 59B x 60Hz), and buffer depth/lead/loss
all moved in the correct direction between a clean LAN run and one under
simulated 60ms latency + 10% loss. Full regression suite re-run clean.
Lands tasks 1.0-1.8 of multiplayer-todo.md: the pure-function test runner,
net_codec (wire format quantizers/pack-unpack), NetworkManager (ENet
transport, manual polling, min-RTT clock sync), MatchNet (handshake,
protocol/tick-rate gating, roster with team+ready state), lobby.tscn (team
columns, switch team, ready toggle), server_boot.tscn (headless dedicated
server with structured logging and an overrun watchdog), and main_menu.gd's
Host/Join-by-IP UI (connecting overlay, cancel, bounded failure path).
Followed by an adversarial review (Opus subagent) that found and fixed two
real bugs - an unvalidated player_name broadcast that let one client's
oversized name head-of-line-block the reliable channel for everyone, and a
server-side roster leak across a host/re-host cycle - plus three gaps in
the test suite itself where a claim of "verified" wasn't actually backed
by what the test checked. All five two-process smoke tests plus the
pure-function suite are green with the strengthened assertions in place.
Josh Creek