re(flight): clean pitch sweep -- magnitudes agree, the interpolation law does not

Fresh flight, row pinning CONFIDENT (margin 0.413), one sweep and nothing before
it. axis_probe now REFUSES to measure on a WEAK pin (ALLOW_WEAK_PIN=1 overrides)
since it is a precondition, not a warning: roll is immune to the up/right
labelling but pitch and yaw are not.

Clock x1.26. Binned by speed, both in game units, against the linear
interpolation of AV_PitchPlus_Min 150 (at MinimumVelocity 100) to _Max 70 (at
MaximumVelocity 1200):

    speed ~435   measured 100.8   predicted 125.6
    speed ~572            113.8             115.7
    speed ~709            126.3             105.7
    speed ~846             83.1              95.7
    speed ~983             72.7              85.8

Supported: the magnitudes (73-126 measured vs 86-126 predicted) and a falling
high-speed end. NOT supported: the interpolation law. Scatter is +-25%, the two
fastest bins hold 1 and 2 windows (the first moments before the speed bled), and
the slowest bin misses in the wrong direction.

The flaw is structural, not statistical: a sweep DRIVEN by the speed bleeding
cannot dwell at either extreme, which is exactly where the law is most testable.

What would settle it: hold a settled throttle and pitch for ~1 SECOND, so speed
barely moves inside the burst and each burst gives one honest (speed, rate) point;
repeat at LT / neutral / RT for three clean points at known speeds. Recorded as
the next design rather than attempted as a fifth variation of the same sweep.

docs/re/captures/pitch-rate-curve-clean.csv

@@ -0,0 +1,40 @@
+t,speed_units_per_wall_s,rate_deg_per_wall_s
+0.52,1498.8,37.47
+1.03,1276.1,91.64
+1.53,1045.5,90.49
+2.05,1133.7,118.83
+2.55,885.4,129.88
+3.06,777.7,127.51
+3.57,788.1,174.38
+4.07,546.7,157.56
+4.57,536.2,124.41
+5.09,946.8,161.62
+5.59,821.9,138.76
+6.09,636.7,131.35
+6.61,529.3,133.56
+7.13,674.7,162.01
+7.63,669.2,125.78
+8.17,746.4,127.35
+8.67,821.1,154.31
+9.17,569.7,135.57
+9.67,645.2,167.18
+10.19,720.0,150.99
+10.69,698.6,123.63
+11.21,717.0,125.53
+11.72,826.9,165.47
+12.23,471.3,114.2
+12.77,594.0,146.56
+13.29,858.3,174.73
+13.79,734.8,130.83
+14.31,502.8,91.53
+14.81,822.9,168.67
+15.31,696.2,166.37
+15.83,462.2,109.81
+16.33,791.0,162.87
+16.85,854.4,155.88
+17.37,536.8,98.26
+17.89,873.1,182.24
+18.41,630.0,155.61
+18.93,584.1,129.64
+19.43,699.6,132.45
+19.97,805.1,142.68

docs/re/flight-speed-law.md

@@ -585,3 +585,38 @@ measurement taken through a doubtful instrument cannot settle it.
 
 Data: [aliased, for reference](captures/rate-curve-aliased-BAD.csv) ·
 [windowed](captures/rate-curve-windowed.csv).
+
+
+## The clean sweep: magnitudes agree, the LAW does not follow 🟡
+
+Fresh flight, row pinning **CONFIDENT** (margin 0.413), one sweep and nothing before
+it — the conditions the previous attempt lacked. Clock 01:16.08 → 01:41.46 (×1.26).
+Binned by speed, both converted to game units:
+
+| speed (game) | measured °/game-s | linear interpolation of the caps |
+|---|---|---|
+| ~435 | 100.8 | 125.6 |
+| ~572 | 113.8 | 115.7 |
+| ~709 | 126.3 | 105.7 |
+| ~846 | 83.1 | 95.7 |
+| ~983 | 72.7 | 85.8 |
+
+(prediction = `AV_PitchPlus_Min` 150 at `MinimumVelocity` 100 → `_Max` 70 at
+`MaximumVelocity` 1200, interpolated linearly.)
+
+**What this supports:** the magnitudes are right — measured 73–126 °/game-s across
+speeds 400–1 050 against a predicted 86–126 — and the high-speed end falls, as a
+speed-dependent cap should.
+
+**What it does not support:** the interpolation *law*. The scatter is ±25 %, the two
+fastest bins hold only 1 and 2 windows each (they are the first moments before the
+speed bled), and the slowest bin disagrees in the wrong direction (100.8 measured vs
+125.6 predicted). A sweep that is *driven* by the speed bleeding cannot spend long at
+either extreme, which is exactly where the law is most testable.
+
+**The design that would settle it**, and why this one cannot: hold a *settled*
+throttle, pitch for only **~1 second**, and read the rate — the speed barely moves
+inside a 1 s burst, so each burst yields one honest `(speed, rate)` point. Repeat at
+`LT` / neutral / `RT` for three clean points at known speeds, instead of one smeared
+sweep. Data:
+[`captures/pitch-rate-curve-clean.csv`](captures/pitch-rate-curve-clean.csv).

tools/re-capture/axis_probe.py

@@ -122,8 +122,14 @@ def pin_rows(w, off, cfg):
     up_i = max(cand, key=lambda r: abs(ys[r]))
     right_i = [r for r in cand if r != up_i][0]
     print(f"# row world-Y means: {[round(y,3) for y in ys]}  (forward = row {f_i})")
-    print(f"#   -> up = row {up_i}, right = row {right_i}"
-          f"   {'CONFIDENT' if abs(ys[up_i]) - abs(ys[right_i]) > 0.3 else 'WEAK — craft may not be level'}")
+    margin = abs(ys[up_i]) - abs(ys[right_i])
+    ok = margin > 0.3
+    print(f"#   -> up = row {up_i}, right = row {right_i}   margin {margin:.3f}   "
+          f"{'CONFIDENT' if ok else 'WEAK — craft is not level'}")
+    if not ok and os.environ.get("ALLOW_WEAK_PIN") != "1":
+        sys.exit("refusing to measure with a WEAK row pin — fly level first, or set "
+                 "ALLOW_WEAK_PIN=1 if the caller genuinely does not care "
+                 "(roll is immune to the labelling; pitch and yaw are not)")
     return up_i, right_i