docs(spec): libxce-alloc-preason-equality review fixes; new scheduler-sim-discrete-clock spec

libxce-alloc-preason-equality (requirements, design, tasks; not yet approved):
- alloc_eq compares `from` and excludes only instid; the scheduler stamps
  `from` with the deciding session's start, the same clock reading that
  is recorded as beginRound, so a replay reproduces it.
- every comparator takes an optional char** why: a malloc'd description
  of the first difference, owned and freed by the caller; --sim-verify
  mismatch lines print it (resolves bug-1881).
- job_preason_eq is new full-match behavior, not a relocation (bug-1845
  keeps the simulator main-reason-only); the three white-box test files
  switch to it and keep their sim_verify.c include.
- alloc_eq stays separate from merge_job_alloc()'s same_alloc_slot()
  (bug-1863), which does match on instid.

scheduler-sim-discrete-clock (initialized): remove --sim-speed so the
simulator clock moves only at recorded timestamps and a replayed
session_start equals the recorded beginRound exactly.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.kiro/specs/scheduler-sim-discrete-clock/requirements.md

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+# Requirements Document
+
+## Project Description (Input)
+**Who has the problem:** operators and engineers who replay scheduler recordings with `xce_scheduler --sim` / `--sim-verify` or the simulation REPL, and the libxce-alloc-preason-equality work, which needs a replay to reproduce values derived from a session's start time bit-for-bit.
+
+**Current situation:** the simulator is already event-driven: `sim_loop.c` never sleeps, and it jumps the virtual clock with `sim_advance_virtual_clock()` to each recorded event timestamp and to each recorded session's `beginRound`. `--sim-speed` (default 1, help text "1=real-time") does not pace anything. It only scales how far the clock drifts with real elapsed time between those jumps (`xce_core_now() = virtual_clock_base + elapsed_real * speed_num / speed_den`). So at the default speed, every clock reading in a replay (`core->session_start`, the `--sim-record` `beginRound`, decision timestamps, REPL position) depends on how fast the host happens to run. For example, a replayed session's `session_start` lands slightly after the recorded `beginRound`. Only `--sim-speed 0` is deterministic. The REPL exposes the same knob as its `speed` parameter.
+
+**What should change:** make the simulator a pure discrete-event simulation. Remove `--sim-speed`, the REPL `speed` parameter, and the simulator's use of `speed_num`/`speed_den`, so the virtual clock moves only when the replay reaches a recorded event or round timestamp and never drifts with real time. Guarantee that a replayed session's `core->session_start` equals the recorded ReplaySession `beginRound` exactly, so values derived from it (for example `xce_alloc_t.from`, spec libxce-alloc-preason-equality Requirement 4.3) reproduce under `--sim-verify`. Amend the scheduler-core spec where it defines the speed modes (Req 5 AC 3 mode table, AC 13 simulation startup). Expected touch points: `main.c` CLI, `sim.c` `sim_set_virtual_clock()`, `sim_loop.c`, `repl_params.c`/`repl_info.c`, `core_clock.c`/`core.h`, about 20 scheduler tests that set a speed, and `src/docs/deployment.md`. Normal-mode (live) scheduling is unchanged.
+
+## Requirements
+<!-- Will be generated in /kiro-spec-requirements phase -->

.kiro/specs/scheduler-sim-discrete-clock/spec.json

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+{
+  "feature_name": "scheduler-sim-discrete-clock",
+  "created_at": "2026-09-28T08:46:06Z",
+  "updated_at": "2026-09-28T08:46:06Z",
+  "language": "en",
+  "phase": "initialized",
+  "approvals": {
+    "requirements": {
+      "generated": false,
+      "approved": false
+    },
+    "design": {
+      "generated": false,
+      "approved": false
+    },
+    "tasks": {
+      "generated": false,
+      "approved": false
+    }
+  },
+  "ready_for_implementation": false
+}
+
+