Preserve observed progression steps in exercise forecasts

docs/forecasting.md

@@ -51,10 +51,16 @@ evidence conservative. A stall means failing to improve the rep best at the
 current load, including drops/recoveries rather than counting every rebound as
 new progress.
 
-The usual pre-increase reps and an actually observed load increment are inferred
-from the recent 24 sessions. Load increases are allowed at the inferred threshold;
+The usual pre-increase reps and most common load increment are inferred
+from the recent 24 sessions. The model preserves the observed mix of load
+increments from its transition window rather than replacing every increase with
+the most common one. Jumps over 15% of their original source load are excluded
+from progression evidence. Load increases are allowed at the inferred threshold;
 their reset reps come from actual transitions. No fixed 8–12 prescription is
 hardcoded. If there are no observed increases, the model cannot invent them.
+Rep-building transitions are excluded at the ceiling, so clipping a rep gain
+cannot turn it into artificial evidence of a stall. Actual repeats and the
+explicit repeat-set prior remain in the model.
 
 The next set is the most likely **joint** outcome. For longer horizons, 512
 deterministically seeded trajectories produce scenario sets at the median load
@@ -87,15 +93,15 @@ results, not independent prospective validation or a guarantee for every exercis
 
 | Horizon | Holdouts | Model | Load MAE (kg) | Rep MAE | E1RM MAE (kg) |
 | --- | ---: | --- | ---: | ---: | ---: |
-| Next session | 1,929 | Learned transitions | 0.312 | 0.692 | 1.893 |
+| Next session | 1,929 | Learned transitions | 0.272 | 0.687 | 1.863 |
 | Next session | 1,929 | Repeat last set | 0.506 | 0.800 | 2.395 |
 | Next session | 1,929 | Damped trend | 0.374 | 0.800 | 2.133 |
 | Next session | 1,929 | Linear trend | 0.422 | 0.800 | 2.118 |
-| 4 sessions | 1,636 | Learned transitions | 1.022 | 1.084 | 3.243 |
+| 4 sessions | 1,636 | Learned transitions | 0.953 | 1.030 | 3.112 |
 | 4 sessions | 1,636 | Repeat last set | 1.884 | 1.145 | 4.159 |
 | 4 sessions | 1,636 | Damped trend | 1.074 | 1.145 | 3.436 |
 | 4 sessions | 1,636 | Linear trend | 1.201 | 1.145 | 3.581 |
-| 8 sessions | 1,308 | Learned transitions | 1.782 | 1.174 | 4.114 |
+| 8 sessions | 1,308 | Learned transitions | 1.716 | 1.173 | 4.151 |
 | 8 sessions | 1,308 | Repeat last set | 3.545 | 1.158 | 5.906 |
 | 8 sessions | 1,308 | Damped trend | 1.903 | 1.158 | 4.518 |
 | 8 sessions | 1,308 | Linear trend | 2.056 | 1.158 | 4.845 |
@@ -104,6 +110,21 @@ The learned model improves aggregate load and E1RM errors at all tested horizons
 At eight sessions it does **not** beat persistence on reps; difficult sessions
 remain unpredictable. The UI includes exercise-specific recent error metrics.
 
+After correcting the collapsed load increments and artificial ceiling repeats,
+next-session and four-session errors improved over the original transition model.
+Eight-session load error improved from 1.782 to 1.716 kg, but E1RM error rose
+slightly from 4.114 to 4.151 kg. This adjustment is not an accuracy gain at every
+horizon. All 23 unit tests pass, including mixed increments, ceiling transitions,
+outlier increases and unchanged plateau behaviour.
+
+Peter's Stiff Leg Deadlift (TNG) eight-week scenario changes from 181 kg × 7 to
+183 kg × 6, and its 26-week scenario from 183.5 kg × 7 to 188 kg × 6. These are
+joint load/rep outcomes: a higher load does not necessarily mean a higher E1RM
+at every horizon. DB Bulgarian Split Squat's 26-week historical scenario changes
+from 39 kg × 10 to 39.5 kg × 11; its history ends on 11 January 2024. The current
+Smith machine Bulgarian split squat has only two sessions and remains withheld
+until four valid sessions are available.
+
 For 30 degrees Smith Press, the latest block has 39 sessions. The current load
 block contains seven sessions at 93.5 kg, progressing 4→5→6→6→6→6→7 reps.
 Three sessions did not improve the rep best. The inferred threshold is nine reps