feat(routing-policy): experimental 'ledbat' delay-based scavenger preset - #4112
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A new opt-in routing-policy preset inspired by LEDBAT (RFC 6817). It changes
no default — you get it only via preset:ledbat.
decideLedbat provisions a lean symmetric mux=3 over multi-hop with "auto" byte
distribution, re-evaluated every 20s (chat stays single-route). tickLedbat is
the scavenger: it tracks each leg's EWMA-smoothed delay and a per-leg base
(running-min) delay, then acts on the queuing delay = smoothed - base.
- Back off (yield): if any active leg's queuing delay exceeds 60ms, demote the
highest-queuing-delay non-primary active leg to warm standby, shrinking the
active set toward 1 (never parks leg 0, never tears down).
- Grow: while every active leg reads within 60ms of its base and the active set
is below the mux cap of 3, re-promote one parked leg (reserve only, no fresh
dial).
One arbitrated action per tick, integer/float + map state only (no time/rand),
so it is deterministic and byte-identical under wazero and native compilation.
Registered in preset.Names, OnTick/Decide dispatch, and the wasm manifest; the
bundle.wasm is rebuilt so the wazero path carries it. Native unit tests cover
the decide shape and the back-off / floor / grow tick rules, and the
native<->wazero decide+tick parity test is extended to ledbat.
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Adds an opt-in routing-policy preset
ledbat, a delay-based background/scavenger multipath policy inspired by LEDBAT (RFC 6817). It changes no default — selectable only viapreset:ledbat.decideLedbatprovisions a lean symmetricmux=3over multi-hop withautobyte distribution, re-evaluated every 20s (chat stays single-route).tickLedbattracks each leg's EWMA-smoothed delay and a per-leg base (running-min) delay and acts on the queuing delay = smoothed − base:One arbitrated action per tick, integer/float + map state only (no
time/rand), so it is deterministic and byte-identical under wazero and native compilation.Registered in
preset.Names, theDecide/OnTickdispatch, and the wasm manifest;bundle.wasmis rebuilt (TinyGo) so the wazero path carries it. Native unit tests cover the decide shape and the back-off / floor / grow tick rules; the native↔wazero decide+tick parity test is extended toledbat.go test ./pkg/router/policy/...passes, including the wazero parity test;go build .passes.