Module expect_engine 

Expect engine backed by expectrl — implements goexpect-equivalent semantics.

This module provides:

• PtyStream: a wrapper around OwnedFd that implements Read + Write + NonBlocking for use with expectrl’s Session.
• StubProcess: a Healthcheck impl for processes managed externally (by runc/runsc) rather than spawned by expectrl.
• ExpectCase, BatchStep, etc.: types for the LLM tool layer.

goexpect compatibility

goexpect	expectrl	Our tool
Expect(re, timeout)	session.expect(Regex("..."))	shell_expect
ExpectSwitchCase([]Caser)	session.expect(Any::boxed(..))	shell_expect_cases
ExpectBatch([]Batcher)	Sequential send+expect	shell_batch
Send(string)	session.send(string)	shell_write
SendSignal(sig)	External kill	shell_signal
Tags: OK/Fail/Continue/Next	CaseTag	flow control

macOS compatibility

expectrl handles platform differences internally. On macOS it uses posix_openpt / grantpt / unlockpt for PTY allocation and fcntl(O_NONBLOCK) for non-blocking I/O — no Linux-specific APIs needed in this module.

Structs

BatchStepResult

Result of a single batch step.

ExpectCase

A single case in a switch/case expect operation.

PtyStream

A stream wrapper around an OwnedFd that implements the traits expectrl needs: Read + Write + NonBlocking.

StubProcess

A stub process for use with expectrl’s Session when the actual process is managed externally (by runc/runsc).

Enums

BatchStep

A single step in a batch sequence.

CaseTag

Flow control tag for expect cases (maps to goexpect’s Tag).

Functions

expand_captures

Substitute $1, $2, etc. in template with captured groups.

extract_matches

Extract captures from expectrl’s Captures into a Vec<String>.

session_from_fd

Create an expectrl Session from a PTY controller fd.