A simulated fruit-fly brain (FlyWire connectome) plays Game Boy games on a 24/7 stream.
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acamilo 7b7ebcdf28 session: parallel processes, a launcher and the fault behaviour
SESSION-02: one agent process per fly and one environment process under
the coordinator over the Unix-socket transport, compared against the
in-process composition and a dedicated-thread variant. The mode is the
only thing that changes; the composition, the coordinator, the workers
and the router are the same code in all three.

The launcher is the configured supervisor. It owns a total thread budget
with one allocation per participant, refused as BUSY before anything
starts when the total cannot cover it; the configured client, service,
worker and port identities, proved in Worker.Hello before the
coordinator pins a registration; Worker.Status health on the
supervisor's own monotonic clock at the ipc-v1 section 6 budgets; and
reaping, where Worker.Shutdown is the request and the operating system
is the guarantee.

The worker executable is a subcommand of this crate's one binary, which
is what implementation.md section 2 allows in place of a separate
worker crate.

The coordinator's fault behaviour: every failure names the participant
it is attributed to, every domain call has a caller-side deadline so a
dead participant is a diagnosed outcome rather than a hang, and failing
fences the epoch -- the boundary stops, the handles drop, and no further
transition or publication is allowed. Agent.Initialize now carries the
launcher's allocation, and an agent refuses one asking for more.

tests/processes.rs proves every acceptance bullet once per execution
mode, and the two section 4 rows SESSION-01 could not reach in one
process: a router restart during a world advance, and an old worker's
reply after a restart. measure compares the three modes at one, two and
four agents; its table is in the crate README, and it is not a capacity
claim.
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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 docs: session framework, the contract and session slices 2026-09-22 13:48:09 +00:00
infra docs: row 41 worked, with the survey and the before/after 2026-09-22 11:16:18 +00:00
packages feat(session-types): the TypeScript half of the contracts, over the same fixtures 2026-09-22 11:54:13 +00:00
services session: parallel processes, a launcher and the fault behaviour 2026-09-22 14:33:25 +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.