The /sim filesystem

Inside the guest, /sim is a 9P mount backed by the live game. It is the native human interface: directories describe the world and files carry values.

/sim/time/ut
/sim/bodies/<id>/mu
/sim/vessels/active/telemetry
/sim/vessels/active/ctl/throttle
/sim/events

Read a scalar with cat. Read a coherent vessel document with cat telemetry | jq. Follow a growing stream with tail -f. Write a text value followed by a newline to a control file. The write blocks until the game thread executes it, then succeeds or returns a useful errno.

cat /sim/vessels/active/mass/total
tail -f /sim/events
echo 0.65 > /sim/vessels/active/ctl/throttle

active is an alias for the currently controlled vessel. by-id/<id> targets a particular vessel. Paths use sanitized IDs, so discover them with ls rather than guessing from a display name with spaces or punctuation.

The tree is dynamic. A vessel without RCS has no RCS directory; turning off a telemetry or feature gate can remove a subtree entirely. For exact paths, units, read/write grammar, command phases, and errno behavior, use the filesystem reference.