feat(benchmark): enhance benchmark documentation and add emulated run details

fix(benchmark): update deterministic checks and improve measurement accuracy

fix(service): refine candidate recording and enhance balance assignment logic

test(service): add test for balance recording with preference assignment

docs/benchmark/README.md

@@ -16,11 +16,14 @@ stage and incumbent are retained.
   battery level.
 - Use a cool phone, unplugged, with other applications closed. Record whether
   the device became warm or throttled during the run.
-- Run the benchmark three times after one warm-up run. Do not interact with
-  the page while a run is active.
-- Representative and loaded scenarios should normally complete below five
-  seconds; every scenario must return within ten seconds. These are release
-  measurements, not CI timing assertions.
+- Tap **Run benchmark** once. It first runs every scenario as an unreported
+  warm-up, then records three measured repetitions per scenario. Do not interact
+  with the page while a run is active. The first measured result is the
+  determinism baseline; later repetitions report whether they match it.
+- The original target was below five seconds for representative and loaded
+  scenarios, with a ten-second planning ceiling for every scenario. The owner
+  accepted six to seven seconds for the loaded scenario on 2026-09-25. These
+  are release measurements, not CI timing assertions.
 - Keep the copied report unchanged, including any incomplete outcomes or
   hardware limitations. No mobile-device measurement is claimed by the source
   tree until a human records it here.
@@ -29,3 +32,43 @@ The browser page uses the same `createPlanningCalculation(request)` context as
 the calendar and adds no solver or backend dependency. The ten-second release
 ceiling applies to planning latency; trace delivery is reported separately and
 cannot replace a valid planning outcome.
+
+## Hardware status
+
+No reference-phone run has been recorded. The project owner elected to close
+the release tickets on 2026-09-25 using the emulated run below, accepting its
+six-to-seven-second loaded planning time and the observed post-result trace UI
+pause. This is an explicit release exception, not a reference-phone measurement
+or proof of physical-device responsiveness.
+
+## Emulated browser run — 2026-09-25
+
+Chromium 149.0.7827.55 on an AMD Ryzen 7 7800X3D (x86_64), headless at
+412×915 pixels, device scale 2.625, touch enabled, and 4× CPU throttling.
+One full warm-up was excluded, followed by three measured repetitions. All
+five scenarios returned within ten seconds of planning time and complete
+results matched across repetitions. The loaded year took 5.74–6.17 seconds,
+above the five-second target. A 100 ms main-thread timer observed a maximum
+extra delay of 5,950.9 ms. Worker event timestamps place the four loaded-year
+pauses of 4.0–6.0 seconds after their planning results, around delivery of
+full trace artifacts. This desktop emulation does not establish reference-phone
+performance or responsiveness.
+
+```tsv
+scenario	repetition	preparation_ms	planning_ms	trace_delivery_ms	wall_ms	outcome	last_stage	placements	deterministic	trace_status	trace_candidates
+representative year	1	0.0	443.7	624.7	1069.1	Plan	dates	30	baseline	ready	29451
+representative year	2	0.1	490.0	609.3	1099.4	Plan	dates	30	yes	ready	29451
+representative year	3	0.1	465.5	614.2	1079.8	Plan	dates	30	yes	ready	29451
+typed obligations	1	0.0	157.0	261.2	418.2	Plan	dates	10	baseline	ready	13103
+typed obligations	2	0.0	162.6	255.6	418.2	Plan	dates	10	yes	ready	13103
+typed obligations	3	0.0	163.4	258.2	421.6	Plan	dates	10	yes	ready	13103
+chained earned entitlements	1	0.0	45.3	1.0	47.0	Plan	dates	3	baseline	ready	27
+chained earned entitlements	2	0.1	44.5	0.9	45.5	Plan	dates	3	yes	ready	27
+chained earned entitlements	3	0.1	44.4	0.8	45.4	Plan	dates	3	yes	ready	27
+deliberate conflict	1	0.0	92.8	0.9	93.8	PlanningConflict		0	baseline	ready	366
+deliberate conflict	2	0.0	44.7	0.2	44.9	PlanningConflict		0	yes	ready	366
+deliberate conflict	3	0.0	43.5	0.6	44.1	PlanningConflict		0	yes	ready	366
+loaded year	1	0.3	5901.5	5677.7	11581.0	Plan	dates	144	baseline	ready	865117
+loaded year	2	0.8	6167.5	7582.4	13752.4	Plan	dates	144	yes	ready	865117
+loaded year	3	0.6	5738.3	6219.5	11962.5	Plan	dates	144	yes	ready	865117
+```