Conventions

Common

nil|string means the function returns either nil or a Lua string.
“bytes string” means a Lua string whose contents are raw bytes (binary-safe).
Paths are typically accepted as strings (and in most ward.fs APIs also as ward.fs.path objects).
Most option tables are optional; when omitted, defaults apply.

Ward commands that execute Lua (ward run, ward eval, ward repl) support a configurable sandbox. The most commonly used switches are:

--memory-limit BYTES - maximum Lua memory usage
--instruction-limit N - approximate instruction budget (see notes below)
--timeout SECONDS - wall-clock timeout (also accepts duration strings like 500ms, 2s, 1m)
--threads N - Tokio worker threads

Notes:

Instruction limiting is intentionally coarse. Ward installs a Lua VM hook every 1024 instructions (or less if the configured limit is smaller), so a script may exceed the configured limit by up to 1023 instructions.
The instruction hook does not execute while awaiting Rust async operations (e.g., I/O). Long-running I/O does not consume the instruction budget.
It helps prevent runaway scripts (memory/time/instructions). This is not a secure sandbox for untrusted code.