Adds the interactive simulation REPL's execution-control slice (Req 5
AC 22): a single-threaded input loop (readline-based) supporting
step [N], continue, quit, and help, pausing before the first replay
event and blocking the driver loop while active.
Review round 1 raised two findings, both resolved here:
- GNU readline (GPL) was linked directly into xce_scheduler, a shipped
production daemon. Switched the whole project to libedit (BSD) for
line editing -- scheduler and controller (xce_test) both now use
editline/readline.h, API-compatible (readline()/add_history()).
- Getting a clean regression run after the libedit swap required a
full clean rebuild, which exposed a genuine pre-existing SIGSEGV
(bug-1504): SnapshotData.internalState was a capnp Data field, and
this codebase's capnpc-c backend silently no-ops Data-field
encoding without zero-initializing the caller's stack struct,
leaving an uninitialized capn_ptr written onto the wire. Fixed by
switching internalState to List(UInt8) (with a new internalStateLen
wire field), matching the working FetchFileReply.content/bytesRead
precedent -- no hand-written accessor code needed.
A second, unrelated instance of the same bug class was found in the
controller's WAL-catchup path (WalCatchupEntry.payload) and
deliberately left unfixed as bug-1505, out of scheduler-core's
boundary; needs its own project-wide Data-field audit.
Scheduler suite: 34/34 clean. RED-phase reproduction recorded in
tasks.md (repl_should_pause() step-budget check disabled -> 2/4
tests fail as expected -> reverted -> 34/34 green).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JPPXeKSUXUqcqvzNXY1rzJ
Add sim_record.c (scheduler_t-free .replay writer: ReplayHeader + loaded
SnapshotEntry once, then per-event pass-through and per-session
ReplaySession finalization) and wire --sim-alt-events event-source
selection into sim_loop.c's drain loop, coexisting with task 11.2's
stdout default and task 11.4's --sim-verify. Extract scheduler_t-free
halves out of recording_session.c's begin/end so sim-side code can reuse
the decision-encoding path without gaining an xce_scheduler_t* dependency,
preserving Req 5 AC 17 isolation. Per Req 5 AC 16/19.
Three-layer regression guard (test_sim_isolation.c) proving sim.h/sim.c/
sim_loop.c hold no controller-facing client/cluster-config/capnp-socket
state: source-text scan, struct-body field scan, and nm(1) link-time
undefined-symbol audit of a new isolated sched_sim_isolation_lib target.
