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.
Add sim_loop.c implementing sched_sim_driver_run(): decode .replay
messages in file order, jump the virtual clock to each ReplayEvent's
exact timestamp as it's queued, and run a real push-events/go/drain/
end-session cycle on each ReplaySession boundary (AC 14, AC 18).
Task 11.1 left no picker registered against the isolated core and no
thread backing its cbufs, which deadlocks the decision drain the moment
a real event loop exists. Add plugin_register_core() (registers a
picker against a bare xce_sched_core_t*, no xce_scheduler_t* required)
and extract builtin_fcfs_new_plugin() from register_builtin_fcfs() as a
behavior-preserving factory, plus a picker-driving thread for the sim
driver. Since real resource allocation is unreachable without a live
xce_scheduler_t* (scheduler-allocation spec's job), the sim picker
thread conservatively PENDs every candidate rather than dispatching.
28/28 scheduler suite, 32/32 whole-project tests green.
Add sim.h/sim.c implementing AC 13 steps 1-4: open+validate ReplayHeader,
locate the most recent SnapshotEntry at/before --sim-start-ts, load it via
xce_sched_core_load_snapshot(), and set the virtual clock anchors. Wire
all seven simulation CLI flags into main.c's task-5.2 mode-selection
branch. Event loop itself (step 5) deferred to task 11.2. Fixes two real
bugs found during TDD: a SnapshotEntry_get_ts() use-after-free and a
pend_updates NULL-deref in xce_sched_core_fini() for bare-core callers.
27/27 scheduler suite green, full project build clean.
