942f852092
In this commit, we record the verdict of the drift experiment, and it answers both halves of the question cleanly while pointing them in opposite directions. Time-awareness did re-evolve: the code_drift1 winner is the first evolved router with time-based logic, stamping every liquidity belief, decaying its confidence on a 35 minute half-life, expiring hard bounds outright after 20 minutes, and interpolating between learned beliefs and the bimodal prior by that confidence -- evidence softening with age, structurally unlike lnd's penalty fading. Selection pressure produced exactly the mechanism the experiment was designed to test for. And yet it does not win. On the drift corpus itself the time-aware winner scores 0.417 against the time-less champions' 0.455 and 0.457 -- and most damning, against gen2's 0.456, a router with the same budget and seed style that never saw drift during evolution. lnd's rationale for decay is validated; its necessity is not. At realistic churn, hard evidence bounds degrade gracefully enough that a stale bound costs one retry, which is cheaper than the information the decay machinery throws away. Champions of record remain hb1 and mx_c3, now validated on a fourth held-out tier. We archive the winner's source beside the writeup and update the notebook and CLAUDE.md accordingly.
7.6 KiB
Lab Notebook — LN Routing Evolution
Running log of the GEPA × lnd pathfinding project. Newest entries at the
bottom. Detailed experiment writeups live in experiments/.
2026-07-24 — Project kickoff, evaluator built, loop validated
Goal set by roasbeef: create the next generation of LN routing algorithm, using a payment simulator (improved as far as needed) and GEPA as the guide. Explicitly not tied to the current Dijkstra + mission control paradigm. Dijkstrasden (bitromortac's virtual LN, PR #3) reviewed and mined for ideas — describegraph-loaded graphs, liquidity models, observer traces, scenario sweeps — but not adopted as code: its portal architecture (patched lnd, gossip injection, itests) is built for implementation testing, too heavy and nondeterministic for an optimizer's inner loop.
Built today:
routing/sim_*.gosimulator: real lnd pathfinding + mission control against hidden liquidity, per-direction policies, real forwarding error semantics. Caught an off-by-one porting the mock graph: the amount over channel i isHops[i-1].AmtToForward, notHops[i]— until fixed, every intermediate hop failed with FeeInsufficient.cmd/routesimCLI (~0.3s per 10-payment batch on 200-node nets).- Scenario corpus generator, evaluator, GEPA runners (parameter mode and code mode), codex-CLI reflection wrapper (gpt-5.6-sol headless).
SimRouterparadigm-free interface + candidate slot with overlay builds; seed = simple cheapest-path router with failure blacklisting.
Experiments: see experiments/exp-001-param-smoke.md (smoke run,
budget starvation diagnosed) and experiments/exp-002-param-run1.md
(400-eval parameter run, in flight).
Headline early finding: on a hard bimodal-liquidity example, the
naive 300-line seed router beat the full lnd stack — 33% vs 22% success
at 7.8 vs 112.6 attempts/payment. The lnd defaults burn huge retry budgets
in bimodal small-channel regimes. Detail in
experiments/exp-003-seed-router-vs-lnd.md.
Infra notes: PyPI gepa 0.1.4 lags the repo API — install from git
main. GEPA's budget arithmetic: each candidate costs ~(minibatch +
periodic full-val) evals; 60 evals only bought 7 proposals on the smoke
corpus. Score shaping matters: unbounded attempt penalties (down to −2)
drowned success-rate deltas; penalties now saturate at −0.25 total.
2026-07-24 (night) — run1 verdict, corpus v2, overnight evolution runs
- run1 (params, 400 evals): seed survived. No knob change beat lnd defaults on val aggregate; bimodal specialists won individual examples only. Paradigm > knobs (exp-002). Real lineage now on the dashboard; Litbucket v2 published (https://lnd-routing-command-center.lightning.wiki/).
- Corpus v2 adds Barabási-Albert scale-free nets (800/1500 nodes, log-normal capacities). Baseline: lnd near-parity on scale-free (0.819 vs 0.860) but still behind overall (0.559 vs 0.681) — exp-003.
- Overnight runs in flight: code1 (adaptive gepa↔meta_harness, corpus v1, 240-eval pool) and omni1 (blog recipe via optimize_best_of: gepa+meta_harness explore 100 evals each → fresh gepa continues 160, corpus v2). Preflight passed; reflection = codex/gpt-5.6-sol, meta_harness = claude CLI.
- Farmed out: Fable code-reviewer auditing the simulator's BOLT forwarding semantics + reward-hack surfaces (report-only, results land in a later entry). Cron agent refreshes the dashboard every 30 min.
2026-07-24 (night) — BREAKTHROUGH: evolved router beats lnd + seed
code_hard1 (pure gepa, gpt-5.6-sol) evolved an 872-line router that
wins the sealed test set and generalizes OOD:
- hard sealed test: hb1 0.586 > seed 0.530 > lnd 0.309 (objective)
- OOD corpus-v2 test: hb1 0.545 > seed 0.487 > lnd 0.357
- ~9 attempts/payment vs lnd's ~50, higher success on both.
What it discovered from failure traces alone: an explicit bimodal liquidity prior (rediscovering lnd's own bimodal-estimator hypothesis)
- per-edge liquidity bounds with confidence + risk-adjusted Dijkstra.
Clean (no exploit). Full detail + caveats: exp-006. Champion saved to
champions/router_hb1_v1.go. Sim audit (exp-005) fixed a critical sandbox escape before it was exploited.
Update (code_mix1 follow-up): continuing evolution from hb1 on a
mixed corpus produced mx_c3 (champions/router_mx3_generalist_v1.go),
the best generalist: it dominates hb2, ties hb1 on the hard test (0.583
vs 0.586), wins OOD (0.581 vs 0.545), and has the best combined average
(0.582). Champions of record: hb1 (hard specialist) + mx_c3 (generalist).
Detail: exp-007.
2026-07-24 (day) — MAINNET VALIDATION: champions win on the real graph
Real 12,161-node mainnet snapshot, 100 payments, highest-degree source: mx_c3 0.791 / hb1 0.790 vs lnd 0.694 objective — comparable success (0.81 vs 0.79) at 8.6× fewer attempts (2.3 vs 19.8/payment). The synthetic-bred champions generalize to lnd's home turf. exp-009.
2026-07-24 (evening) — code_gen2: insight transfer works, same ceiling
The small-seed + insights-in-prompt run finished (400/400 evals, 31 accepts — ~4× code_mix1's acceptance rate). Its best candidate reaches champion-class performance on all three held-out tiers (combined 0.638 vs mx_c3's 0.652, hb1's 0.640; mainnet 0.787 at the same 2.3 attempts/payment) but does NOT pass the champions. Three independent lineages now converge on the same paradigm and the same performance band: the interval-belief design looks like a local optimum for these environments. gen2 did evolve two novel mechanisms (in-flight local liquidity reservation; weakest-edge failure attribution) that the sim never rewards — more eval budget in the same regime buys nothing. Champions of record stay hb1 + mx_c3; the next lever is changing the environment (exp-008 background traffic, exp-010 splitting pressure). Detail: exp-011.
2026-07-24 (night) — exp-008 begins: the sim gets a clock and traffic
Built and committed (d11a20dcb) the fidelity upgrade: virtual clock
(MC decay now operates over simulated time; candidates read
view.Now()) + seeded background traffic (naive fee-optimizing senders
move hidden liquidity in every gap; per-channel conservation; same
seed → same exogenous process for all routers). Baseline on the new
drift corpus: the champions' hard bounds do NOT collapse (hb1/mx_c3
~0.46 vs lnd 0.20 on drift-test) and lnd's decay does not close the
gap even now that it operates. But everyone lost ground vs static
(champions ~0.59 → ~0.42), so drift created real headroom. Evolution
run code_drift1 (400 evals, drift-neutral prompt) is live. exp-008.
2026-07-25 — exp-008 VERDICT: time-awareness re-evolves, doesn't win
code_drift1 finished 400/400 (51 accepts). Its winner is the first
evolved router with time logic, and the mechanism is the hypothesized
"interval-softening" form: belief confidence decays on a 35-minute
half-life, hard bounds expire outright at 20 minutes, and edge
probability interpolates conf·learned + (1−conf)·prior — so aging
evidence slides back toward the bimodal prior. Decay of confidence in
evidence, never decay of penalties.
But it does NOT beat the time-less champions, even on drift: drift-test mx_c3 0.457 / hb1 0.455 / gen2 0.456 / drift1 0.417. The sharpest cut: gen2 (same budget, same seed style, never saw drift) beats drift1 on the drift corpus itself. lnd's rationale is validated — staleness pressure is real and selection responds to it — but at realistic churn, hard evidence bounds degrade gracefully enough (a wrong bound costs one retry) that decay machinery buys nothing. Champions of record unchanged: hb1 + mx_c3, now validated on four tiers. Detail: exp-008 writeup.