Module abi 

Well-known cnode slot keys the v3 chain ABI exposes at genesis. Shared between jar-kernel (which populates the slots at chain init) and consumers like the JAVM transpiler (which emit chain Images referencing them).

Under the V1 single-byte ABI a slot is named by a one-byte crate::Key; these constants are the byte values. Wrap with Key::from(BARE_*_SLOT) at the call site — the same u8 → Key boundary the ecall handlers use (Key::from((gpr & 0xFF) as u8)).

Constants

BARE_GAS_SLOT

Root Cap::Instance[Gas{0}] handle. The chain reads this slot to learn its active gas meter.

BARE_HOST_OPEN_SLOT

Cap::Instance[HostOpen] — read-only entry handle for host_open.

BARE_HOST_SAVE_SLOT

Cap::Instance[HostSave] — entry handle for host_save.

BARE_QUOTA_SLOT

Root Cap::Instance[Quota{0}] handle (symmetric to BARE_GAS_SLOT).

BARE_YIELD_RECEIVER_SLOT

Slot the chain Image’s yield_receiver_slot points at, holding the chain’s Cap::Instance[YieldReceiver] (its catch-set; per-block reset). The kernel reads it when routing a yield.

SCRATCHPAD_SLOT

The scratchpad slot: the single cap-shaped data-flow channel between a caller and callee. Its contents may be freely mutated and reset to empty, but the slot itself is “mutably pinned” — MGMT_MOVE/MGMT_SWAP of this slot trap. On CALL the caller’s scratchpad moves to the callee; on HALT/reply the callee’s moves back to the caller; so the running Instance always holds the scratchpad here, and every other frame’s slot[0] is empty (one owner — see the data-flow principle). The fuzz / kernel return path hands the top-level Instance’s slot[0] Cap::Data back as the invocation result.