A simulated fruit-fly brain (FlyWire connectome) plays Game Boy games on a 24/7 stream.
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dev 45621903be session: name the two ways a durable wait ends without an acknowledgment
Review follow-up on the checkpoint store.

A dropped reply channel and an expired caller budget were both reported as
ReplyLost. They are different facts -- the first means the write is over and its
outcome did not reach here, the second means the save is still going -- so they are
now separate outcomes, and the durable wait has its own budget rather than borrowing
the one that bounds a call to a participant. Both still leave durable metadata where
it was, and for both the resolution asks the store about the same checkpoint.

The writer's two bounds refuse at different moments and the comment claimed
otherwise: the outstanding-capture bound is taken before a capture is requested, and
the byte budget cannot be, because a capture's size is not known until it exists. The
byte check, the decision and the change to the byte total are now one critical
section, the peak is sampled after a superseded job's bytes are gone, and the writer's
own bookkeeping is over a type that holds only the outcomes a writer can produce.

The manifest's coordinator.eventWatermarks is {lastSourceStep, issued}; the fixture
illustrated {lastEventId, lastOrdinal}, and the illustration is what changed, because
an event id is derived from the epoch and cannot be compared across the restore that
gives the session a new one.

checkpoint-envelope-v1 section 3 also now says, under the same dated amendment, that
a required-manifest-field change must bump envelopeVersion once production files
exist: contractDigest is taken over the schema set and does not cover this manifest,
so the envelope version is the only thing that can carry such a change.
2026-09-22 18:45:51 +00:00
.forgejo/workflows flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
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apps/stage stage(describe): the public repo URL on the card 2026-09-22 02:08:31 +00:00
data/fafb-v783 flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
docs session: name the two ways a durable wait ends without an acknowledgment 2026-09-22 18:45:51 +00:00
infra Merge fix/chat-ring-persist: the on-screen chat ring survives a sim restart via a hot-dir sidecar 2026-09-22 17:45:59 +00:00
packages session: coherent all-participant checkpoint and recovery 2026-09-22 17:43:43 +00:00
services session: name the two ways a durable wait ends without an acknowledgment 2026-09-22 18:45:51 +00:00
tools flybrain v0.4.0: public tree (history retained privately) 2026-09-21 15:09:46 +00:00
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flybrain

A simulated fruit-fly brain that plays video games. A connectome-constrained spiking network reads the screen, its population rates become controller inputs, and a scalar reward nudges a bounded set of Kenyon-cell to MBON gains.

The library is @flybrain/brain in packages/brain. It holds the connectome dataset format, the LIF kernel, the plasticity rule, the population-rate readout and the activity-map geometry. It holds no game, no emulator and no reward rules: those belong to whatever embeds it.

Workspace layout

Path Contents
packages/brain the library (@flybrain/brain)
data/fafb-v783 FlyWire-derived browser artifacts (CC BY-NC 4.0)
tools/ the Python builder that regenerates data/ from official Codex exports
docs/ overview, dataset format, model, plasticity, readout, integration, limitations, verification
services/flysim the Rust service: brain, emulator, snapshot feed, control API, checkpoints
apps/ planned: one directory per game demo
infra/ planned: deployment for the 24/7 stream (see docs/streaming-plan.md)

Quick start

npm ci
npm test
npm run typecheck

76 tests, about 7 seconds. There is no build step. npx tsx packages/brain/examples/node-random-frames.ts 60 runs the full 139,255-neuron brain with the Game Boy readout on noise frames in plain Node (about 0.9x Game Boy real time single-threaded on a WSL laptop).

Usage

import { NeuralAgent, gameboyDecoderConfig, toButtonMask } from '@flybrain/brain';
import { loadBrainDatasetFromDir } from '@flybrain/brain/node';

const dataset = await loadBrainDatasetFromDir('data/fafb-v783');
const agent = new NeuralAgent(dataset, { decoder: gameboyDecoderConfig() });
agent.warmup(firstFrame);                        // 2,500 ms with plasticity off, then calibrate

// every emulator frame:
const { active } = agent.tick(framebuffer, {     // RGBA 160x144 by default; any size via config
  rewards: [{ value: 0.5 }],                     // scalar rewards your game adapter detected
  boot: !inGame,                                 // relaxes Start/Select throttling on title screens
});
emulator.setButtons(toButtonMask(active));

const checkpoint = agent.exportState();          // bit-exact resume, validated on import

The lower layers (LifNetwork, RewardModulatedStdp, PopulationDecoder) are exported too for hosts that want to run the loop themselves.

integration.md has the full per-frame loop, the fractional frame timing and the checkpoint contract.

Documentation

  • Overview: the pipeline, the layer map and the design principles.
  • Dataset format: artifacts, CSR layout, weight encoding, every role and its count, fingerprinting, regeneration, license.
  • Model: the 1-ms LIF kernel step by step, every default constant, the retina projection, the RNG, state export and version strings.
  • Plasticity: edge selection, the eligibility and reinforcement equations, statistics, topology hash and the explicit non-claims.
  • Readout: scores, exclusive groups, pulse channels, the blocked-direction cooldown, the Game Boy preset table and checkpoint versions.
  • Integration: what a game must provide, the Pokemon Red integration as a worked example, and a sketch of a platformer adapter.
  • Limitations: what is not claimed, what is unproven, measured throughput.
  • Verification: the oracle-test strategy and what each test file covers.
  • Streaming plan: headless capture, Twitch, VM design and the phased plan for a 24/7 stream.
  • Artifact builder: how to regenerate and verify data/fafb-v783.
  • Data attribution: source, license and citations.

Provenance

The network, plasticity rule, readout, FlyWire pipeline and activity viewer were extracted from the fly-plays-pokemon prototype so several game demos can share one core. The default configuration reproduces that prototype's kernel bit for bit, and verbatim copies of its modules live in packages/brain/tests/legacy/ as oracles. Built with Astra.

Licensing

The data/fafb-v783 artifacts are derived from the FlyWire FAFB public Codex v783 exports and are licensed CC BY-NC 4.0. That is a non-commercial license, so a commercial demo needs a different data source or separate permission. Citations and the list of modifications are in data/fafb-v783/ATTRIBUTION.md.

No license has been chosen for the code in this repository yet.

ROMs and save states never enter this repository.