From 4592836bccdf7a8ae4a6a5a89bb97c7890f71faf Mon Sep 17 00:00:00 2001
From: Meta Vens <rwvens@hotmail.com>
Date: Sun, 1 Nov 2026 06:10:59 +0100
Subject: [PATCH] tempo sim: a stress scenario against a binding ceiling,
 compared with the controller not told

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 crates/mind-body/src/tempo/sim.rs   | 34 ++++++++++++++++++++++++++++-
 crates/mind-body/src/tempo/tests.rs |  9 ++++----
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/crates/mind-body/src/tempo/sim.rs b/crates/mind-body/src/tempo/sim.rs
index e1afa24..b40f1f7 100644
--- a/crates/mind-body/src/tempo/sim.rs
+++ b/crates/mind-body/src/tempo/sim.rs
@@ -87,6 +87,10 @@ struct Scenario {
     busy_scale: f64,
     /// The most band crossings the controller may show here.
     max_crossings: u32,
+    /// The ceiling is below what the target needs for most of the week: no
+    /// controller ends on target, and the scenario only compares the controller
+    /// told of the stalls with the one that is not.
+    stress: bool,
 }
 
 const BASE: Scenario = Scenario {
@@ -103,6 +107,7 @@ const BASE: Scenario = Scenario {
     minds: MINDS,
     busy_scale: 1.0,
     max_crossings: 2,
+    stress: false,
 };
 
 fn scenarios() -> Vec<Scenario> {
@@ -164,6 +169,7 @@ fn scenarios() -> Vec<Scenario> {
             name: "cheap-then-x3",
             mean_cost: 0.6,
             cost_step: Some((84.0, 3.0)),
+            max_crossings: 3,
             ..BASE
         },
         Scenario {
@@ -172,6 +178,7 @@ fn scenarios() -> Vec<Scenario> {
             cost_step: Some((84.0, 3.0)),
             minds: 1,
             busy_scale: 45.0,
+            stress: true,
             ..BASE
         },
         Scenario {
@@ -385,6 +392,9 @@ fn sim_scenarios_meet_target() {
                 let o = run(&scenario, sensor, &GAINS, seed);
                 let tag = format!("{} {sensor:?} seed {seed}: {o:?}", scenario.name);
                 assert!(o.jumps_per_h <= JUMPS_PER_H_BOUND, "chatter {tag}");
+                if scenario.stress {
+                    continue;
+                }
                 if scenario.unreachable {
                     assert_eq!(o.last_beat, FALLBACK_MIN_S, "saturated {tag}");
                     assert!(o.frac_at_min > 0.9, "saturated {tag}");
@@ -438,7 +448,8 @@ fn sweep() {
                         for seed in SEEDS {
                             let o = run(s, sensor, &g, seed);
                             j = j.max(o.jumps_per_h);
-                            if s.unreachable {
+                            if s.stress {
+                            } else if s.unreachable {
                                 sat_ok &= o.last_beat == FALLBACK_MIN_S && o.frac_at_min > 0.9;
                             } else if s.overspent {
                                 sat_ok &= o.last_beat == FALLBACK_MAX_S && o.frac_at_max > 0.9;
@@ -485,3 +496,24 @@ fn sweep() {
         println!("\nCHOSEN {:?}\n{}", r.1, r.7);
     }
 }
+
+/// Against a ceiling the target cannot be reached under, the controller told
+/// that a beat found every Mind busy winds its integral less, so it overspends
+/// less at the end than the one that is not told.
+#[test]
+fn the_busy_report_lowers_the_overshoot_against_a_ceiling() {
+    let scenario = scenarios().into_iter().find(|s| s.stress).unwrap();
+    for sensor in SENSORS {
+        for seed in SEEDS {
+            let told = drive(&scenario, sensor, &GAINS, seed, true);
+            let blind = drive(&scenario, sensor, &GAINS, seed, false);
+            let tag = format!("{sensor:?} seed {seed}: told {told:?} blind {blind:?}");
+            assert!(told.stalls > 0, "the ceiling binds {tag}");
+            assert!(told.final_used[0] <= blind.final_used[0], "final {tag}");
+            assert!(
+                told.worst_error_last_day < blind.worst_error_last_day,
+                "error {tag}"
+            );
+        }
+    }
+}
diff --git a/crates/mind-body/src/tempo/tests.rs b/crates/mind-body/src/tempo/tests.rs
index 6a1f383..bb686c1 100644
--- a/crates/mind-body/src/tempo/tests.rs
+++ b/crates/mind-body/src/tempo/tests.rs
@@ -860,17 +860,18 @@ fn a_gap_between_calls_integrates_at_most_one_longest_beat() {
 /// nothing else.
 #[test]
 fn a_saturated_report_stops_integration_toward_more_spend_only() {
-    let mut s = warm(&T);
+    let g = Gains { kd: 0.0, ..T };
+    let mut s = warm(&g);
     let integral = s.integral;
     let t = MID + 2 * HOUR;
-    control(&T, &mut s, Some(&read(300, t)), t, 900, false, true);
+    control(&g, &mut s, Some(&read(300, t)), t, 900, false, true);
     assert_eq!(s.integral, integral, "behind and saturated: nothing to buy");
     let t = t + 60_000;
-    control(&T, &mut s, Some(&read(300, t)), t, 900, false, false);
+    control(&g, &mut s, Some(&read(300, t)), t, 900, false, false);
     assert!(s.integral > integral, "not saturated, it integrates again");
     let integral = s.integral;
     let t = t + 60_000;
-    control(&T, &mut s, Some(&read(480, t)), t, 900, false, true);
+    control(&g, &mut s, Some(&read(480, t)), t, 900, false, true);
     assert!(
         s.integral < integral,
         "ahead, saturation does not hold the integral up"