Experience report: five days running FLE's action layer on a persistent human-shared server (local ~30B model)

[bdambrosio]

For the past five days I've been running FLE's action layer in a regime it wasn't built for — a persistent multiplayer server where an LLM agent and I cohabit the same map in real time (no fast-mode: the agent really walks, my client really joins, the server really autosaves). The agent is a standing "junior factory engineer" persona driven by a local ~30B model, with a bounded work zone, ownership norms, and a hard chat-phrase stop enforced below her reasoning.

Full write-up: Living With a Factorio Agent

Highlights the FLE community might care about:

• Persistent-server survival required repackaging the injected Lua as a real mod — functions in storage make worlds unsaveable, so every autosave crashed the headless server and silently rolled the world back. Details in Functions in storage make world saves impossible — mod-packaged variant for persistent servers #381; the build script that generates the mod from the installed fle package is in the linked repo (factorio/build_mod.py).
• A taxonomy of grounding failures observed live, each fixed in the perception layer rather than the model: force-neutral ore/ground-item blindness (get_entities cannot see neutral-force entities — ground items block placement invisibly #379), the y-axis-inverted "my north is actually south" prior, drills' unserialized drop_position (serialize.lua exposes drop_position for inserters but not mining drills #377), belt-masked pathfinding + collision-embedded path starts (Character pathfinding treats transport belts as walls (collision_mask includes transport_belt) #375, request_path returns not_found at every entity_size when the start position collides #376), and misleading off-grid placement errors (place_entity: off-grid placements yield misleading 'blocked by' errors — placement-grid guard proposal #380).
• The agent turned out to be a good bug reporter for her own harness. When stuck, she reported "the pathfinder is treating my position as an isolated island" — and she was right: her character was embedded in a furnace collision box, invalidating the path start at any clearance size. All seven upstream findings (Character pathfinding treats transport belts as walls (collision_mask includes transport_belt) #375–Functions in storage make world saves impossible — mod-packaged variant for persistent servers #381) started as her failure narrations.
• A modest counterpoint on model scale (n=1, offered as an existence proof, not a benchmark claim): a local ~30B model built and doubled a working iron line and passed grounded-conversation probes against server ground truth, largely because observations are designed for legibility — named output tiles, teaching errors on the placement grid, classified failure reports — rather than requiring program synthesis. We'd like to test this harness against FLE lab-play tasks at some point.

Huge thanks for FLE — the action layer is what made a weeks-scale build possible at all. Happy to answer questions, and the offered patches on #375/#376/#377/#380 stand.