Runtime contract 0.1
intrinsics.json is the language-owned list of intrinsic signatures. Generated Kelft signature tables must agree with this specification. Runtime implementation source remains backend-local.
Persistent vectors and immutable value trees implement JavaScript storage. Every mutation creates a new value path; temporary inout locations update only their explicit root. Native/Wasm allocation strategies do not change this behavior.
Filesystem operations are denied unless the trusted caller supplies read/write roots through KELFT_CAPABILITIES. A build can embed an additional maximum policy; the effective policy is the intersection. Roots and targets resolve real paths, including symlinked existing ancestors of new files. Policy is not read from prompts. Dangling links are resolved before authority checks. If canonicalization cannot establish containment, including inaccessible link traversal, it traps with KRT_CAPABILITY; errors from authorized file operations remain recoverable. This adapter assumes no hostile concurrent filesystem mutation; it is not an OS sandbox. Node's own APIs are unavailable to Kelft source except through this contract.
The trusted compiler/verifier additionally uses artifact_run: a versioned host service that executes already-emitted artifacts through a fixed target registry. It performs no lexing, parsing, typing, lowering, or code generation. Execution authority (execute: true) is separate from filesystem grants and is never granted by Intent IR v0 or delegated to child artifacts. This is full executable-code authority, reserved for the trusted compiler/test driver. Unknown target IDs fail. There is no arbitrary program-name/process-spawn operation in Kelft-SH. The direct Linux artifact registry supports supplied ELF64 x86-64 executables and optional pinned JavaScript/Wasm engines. Those optional execution engines are not dependencies of native compilation or rebuilding.
The JavaScript host's fixed artifact registry supports wasm through an installed Rust driver, alongside javascript. It never falls back between targets. The WASI profile returns DRIVER_REQUIRED for artifact_run: external execution and Intent fixture evidence use the separate driver protocol.
utf8_decode returns a recoverable Result; bytes_to_string traps on invalid UTF-8. create_dir is bounded by write roots. write_once writes exclusively and permits an identical-content retry, supporting content-addressed immutable ledger entries.
Filesystem paths use the current host's path rules through explicit host operations. Recoverable filesystem errors use the language-defined codes ENOENT, EACCES, EEXIST, ENOTDIR, EISDIR, or IO_ERROR; every adapter maps host errors into this set. EPERM is normalized to EACCES. Permission-policy violations trap with KRT_CAPABILITY instead. String split/replace use literal, nonoverlapping matches and preserve empty segments. An empty separator traps with KRT_EMPTY_SEPARATOR, preventing UTF-16-based splitting. Canonical persisted module identities use project-relative forward slashes. No wall clock, environment lookup, randomness, or directory enumeration is exposed.
Source: public Kelft compiler, commit f567c21684362db37e0aa0a68e71e7614502c45a. Compiler 0.1.0-alpha.2; Core 0.1; Intent 0.2.