SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

airfrans-high-reynolds-drag-extrapolation

claude-code claude-opus-4-8 ✗ failed GOOD_FAILURE ↑ View task
Solved from the instruction alone, tests/ and solution/ were withheld from the agent's workspace and restored only for grading.
Reward = tests/test.sh exit code (0 → resolved); the classification below is post-hoc and cannot change it.
Classification , post-hoc; cannot change the reward
GOOD_FAILUREHonest miss, the agent ran correctly but couldn't solve it. Expected for a hard task; the task is sound.
SubtypeIncomplete Implementation / Timeout
EvidenceAgent discovered through systematic experimentation that gentle velocity augmentation (vel_mult=0.08, vel_mult_hi=0.25) with Huber loss (beta=0.3) and Reynolds scaling (cd_exp=-0.21) achieved mean_nrmse≈0.069 at T70 threshold (step 103-104). This was approaching the target of 0.076. However, trajectory ends mid-experiment (step 133+) with final configurations still running (`runbg4.py` testing β=0.2, epochs=120, vel_mult_hi=0.30). Agent appears to have timed out before completing training with best-discovered configuration. Checkpoint submitted scored 0.46 (raw) vs target 0.50 (reward=0.0).
Root causeThe agent correctly identified and systematically explored the velocity extrapolation challenge through pseudo-holdout validation, discovering effective techniques (physics-informed augmentation, Huber loss). However, the exploration took many iterations (130+ steps) and ran out of time before completing full training with the best-discovered configuration. The final checkpoint reflects incomplete experimentation rather than the agent's best-discovered approach.
RecommendationN/A - task is fine. The task specification is clear (velocity extrapolation challenge), tests are sound (hidden-set evaluation), and the task is solvable (agent's experiments show ~0.069 achievable). The failure was execution/time management, not task design. To improve performance: the agent should have (1) recognized the time budget earlier, (2) prioritized fewer, targeted experiments, or (3) run final training in parallel sooner to submit the best early result rather than continuing to iterate.
Trajectory
Tool-by-tool agent trajectory
195 tool calls · 3 tool types · 195 steps
Aerodynamicists increasingly lean on learned surrogates to skip expensive CFD runs, and one of the most useful things such a surrogate can do is read an airfoil's surface state and tell you the integrated forces on it. That is the job here. For every simulated case you are handed the airfoil's surface as a cloud of 256 points. Each point carries four numbers: its x and y position along the chord-normalized profile, and the two free-stream conditions for the case: the inlet velocity and the angle of attack, repeated on every point so the network always has them at hand. From that surface cloud you must predict the case's two force coefficients, drag and lift. The cases come from a campaign of RANS simulations spanning many airfoil shapes and flow conditions. Your training and validation splits cover part of that campaign; the cases you are ultimately scored on are sampled from the higher-speed, higher-Reynolds end of it, so the evaluation reaches beyond the inlet velocities present in your training data. Plan for that extrapolation rather than assuming the scored cases look just like training. ## Files - `/app/data/train/split.pt` and `/app/data/val/split.pt`: each is a dict with `points` (a `[N, 256, 4]` float32 tensor) and `targets` (a `[N, 2]` float32 tensor of `[C_D, C_L]`). Load them with `torch.load(path, weights_only=True)`. - `/app/data/public_test/split.pt`: a dict with `points` only (no targets), handy for checking that your inference pipeline runs end to end. - `/app/task_config.json`: point count, input dimension, target count, the architecture sizes, and the default training settings. - `/app/feature_schema.json`: what each input channel and target means. - `/app/candidate_model.py`: the fixed PointNet you must train. Leave the architecture alone; your checkpoint has to load straight back into it. - `/app/dataset.py`: helpers for loading a split and standardizing it. - `/app/train.py`: a small starter loop. Treat it as a starting point, not a ceiling. ## The model The architecture is fixed: a shared per-point MLP (`4 -> 64 -> 128 -> 256`), a global max-pool over the 256 points, and a head (`256 -> 128 -> 64 -> 2`). You are free to change everything about how you train (the loss, the normalization, augmentation, the schedule, model selection) but not the network itself. ## What to hand back Write your trained checkpoint to `/app/outputs/model.pt` as a dict containing: - `state_dict`: your model's `state_dict()`. - `feat_mean`, `feat_std`: length-4 tensors that standardize the point features before the forward pass. - `targ_mean`, `targ_std`: length-2 tensors that map the model's outputs back into physical coefficient units. All four normalization tensors must be present. Your weights are loaded back into this exact architecture and run on the scored cases, so the checkpoint has to match it and the de-standardized `[C_D, C_L]` predictions are read straight from the model output. ## What you are optimizing You are predicting the two force coefficients `[C_D, C_L]` for each case, and the quality of your predictions is measured by how close they are to the true coefficients. Lower error is better, and both the drag and the lift coefficient matter, so aim to do well on both rather than trading one off against the other.
Let me start by exploring the environment to understand what I'm working with.
I'll start by exploring the environment to understand the task, the data, and the provided code.
bash
cd /app && ls -la && echo "---- task_config ----" && cat task_config.json && echo "---- feature_schema ----" && cat feature_schema.json
output
total 21
drwxrws---  3 h2tagent h2tagent 4096 Jun 19 21:15 .
drwxr-xr-x 26 root     root     4096 Jun 19 21:26 ..
-rw-rw----  1 h2tagent h2tagent 2093 Jun 19 21:13 candidate_model.py
drwxrws---  5 h2tagent h2tagent 4096 Jun 19 21:13 data
-rw-rw----  1 h2tagent h2tagent 1411 Jun 19 21:13 dataset.py
-rw-rw----  1 h2tagent h2tagent  723 Jun 19 21:13 feature_schema.json
-rw-rw----  1 h2tagent h2tagent  547 Jun 19 21:13 task_config.json
-rw-rw----  1 h2tagent h2tagent 2900 Jun 19 21:13 train.py
---- task_config ----
{
  "task_id": "airfrans-high-reynolds-drag-extrapolation",
  "dataset_name": "airfrans-original-subset",
  "n_points": 256,
  "in_dim": 4,
  "n_targets": 2,
  "chord_axis": 1,
  "aoa_index": 3,
  "lift_index": 1,
  "velocity_index": 2,
  "seed": 20260518,
  "model": {
    "point_mlp": [64, 128, 256],
    "head": [128, 64]
  },
  "training": {
    "epochs": 40,
    "batch_size": 32,
    "lr": 0.001,
    "weight_decay": 0.0001
  },
  "evaluation": {
    "primary_metric": "mean_nrmse",
    "secondary_metrics": ["worst_nrmse", "cd_nmae"]
  }
}
---- feature_schema ----
{
  "version": "airfrans-original-subset-v1",
  "point_cloud": {
    "n_points": 256,
    "in_dim": 4,
    "channels": [
      {"name": "x", "description": "Airfoil-surface node x coordinate (chord-normalized)."},
      {"name": "y", "description": "Airfoil-surface node y coordinate (chord-normalized)."},
      {"name": "inlet_velocity", "description": "Free-stream inlet velocity magnitude in m/s, broadcast to every point."},
      {"name": "angle_of_attack", "description": "Free-stream angle of attack in radians, broadcast to every point."}
    ]
  },
  "targets": [
    {"name": "C_D", "description": "Drag coefficient of the airfoil."},
    {"name": "C_L", "description": "Lift coefficient of the airfoil."}
  ]
}
Let me look at the model, dataset, and train files.
Let me examine the provided model, dataset, and training code.
bash
cd /app && echo "==== candidate_model.py ====" && cat candidate_model.py && echo "==== dataset.py ====" && cat dataset.py && echo "==== train.py ====" && cat train.py
output
==== candidate_model.py ====
"""PointNet regressor for the airfoil force-coefficient task.

Your trained weights are loaded back into the exact module returned by
build_model and a forward pass is run on held-out point clouds, so the
architecture is part of the task contract. The model maps a surface point cloud
[B, P, in_dim] carrying per-point geometry and broadcast flow conditions to
n_targets coefficients via a shared per-point MLP, global max-pool, and a head.
Output is in standardized target space and is mapped back to physical units
afterward.
"""

from __future__ import annotations

from typing import Mapping

import torch
import torch.nn as nn


class SharedMLP(nn.Module):
    def __init__(self, channels: list[int]) -> None:
        super().__init__()
        layers: list[nn.Module] = []
        for i in range(len(channels) - 1):
            layers += [nn.Conv1d(channels[i], channels[i + 1], 1), nn.BatchNorm1d(channels[i + 1]), nn.GELU()]
        self.net = nn.Sequential(*layers)

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        return self.net(x)


class PointNetRegressor(nn.Module):
    def __init__(self, in_dim: int, point_mlp: list[int], head: list[int], n_targets: int) -> None:
        super().__init__()
        self.n_targets = n_targets
        self.encoder = SharedMLP([in_dim, *point_mlp])
        head_layers: list[nn.Module] = []
        dims = [point_mlp[-1], *head]
        for i in range(len(dims) - 1):
            head_layers += [nn.Linear(dims[i], dims[i + 1]), nn.GELU()]
        head_layers += [nn.Linear(dims[-1], n_targets)]
        self.head = nn.Sequential(*head_layers)

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        x = x.transpose(1, 2)
        feat = self.encoder(x)
        pooled = feat.max(dim=2).values
        return self.head(pooled)


def build_model(config: Mapping) -> PointNetRegressor:
    m = config["model"]
    return PointNetRegressor(
        in_dim=int(config["in_dim"]),
        point_mlp=[int(c) for c in m["point_mlp"]],
        head=[int(c) for c in m["head"]],
        n_targets=int(config["n_targets"]),
    )
==== dataset.py ====
"""Point-cloud dataset utilities for the airfoil force-coefficient task.

On-disk format per split: a single split.pt containing a dict with key points
(tensor [N, P, in_dim], float16 on disk) and, for labeled splits, targets
(tensor [N, n_targets], float32). The public_test split ships points only; the
hidden split ships points and labels separately and only points are exposed to
the model at inference.
"""

from __future__ import annotations

from pathlib import Path

import torch


def load_split(split_dir: str | Path) -> tuple[torch.Tensor, torch.Tensor | None]:
    payload = torch.load(Path(split_dir) / "split.pt", map_location="cpu", weights_only=True)
    targets = payload["targets"].float() if "targets" in payload else None
    return payload["points"].float(), targets


def coord_standardizer(points: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor]:
    flat = points.reshape(-1, points.shape[-1])
    mean = flat.mean(dim=0)
    std = flat.std(dim=0).clamp_min(1e-8)
    return mean, std


def target_standardizer(targets: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor]:
    mean = targets.mean(dim=0)
    std = targets.std(dim=0).clamp_min(1e-8)
    return mean, std


def iter_indices(n: int, batch_size: int, shuffle: bool = True):
    idx = torch.randperm(n) if shuffle else torch.arange(n)
    for start in range(0, n, batch_size):
        yield idx[start : start + batch_size]
==== train.py ====
"""Weak baseline trainer: single global-pool PointNet, plain MSE, short budget.

Standardizes point coordinates and targets, trains the pinned regressor to
predict standardized targets under MSE, and saves the four normalization
tensors alongside the state_dict. No augmentation, no per-target weighting, no
early stopping. Candidates are expected to do better on the held-out regime --
input jitter/rotation augmentation, deep
…[truncated]
Now let me understand the data. Let me load the splits and examine them.
Now let me examine the actual data to understand its distribution, especially the train/val/test split characteristics that matter for extrapolation.
bash
cd /app && python3 -c "
import torch
for split in ['train','val','public_test']:
    p = torch.load(f'data/{split}/split.pt', weights_only=True)
    print('====', split, '====')
    print(' keys:', list(p.keys()))
    pts = p['points']
    print(' points shape/dtype:', pts.shape, pts.dtype)
    if 'targets' in p:
        t = p['targets']
        print(' targets shape/dtype:', t.shape, t.dtype)
"
output
==== train ====
 keys: ['points', 'targets']
 points shape/dtype: torch.Size([630, 256, 4]) torch.float32
 targets shape/dtype: torch.Size([630, 2]) torch.float32
==== val ====
 keys: ['points', 'targets']
 points shape/dtype: torch.Size([80, 256, 4]) torch.float32
 targets shape/dtype: torch.Size([80, 2]) torch.float32
==== public_test ====
 keys: ['points']
 points shape/dtype: torch.Size([100, 256, 4]) torch.float32
bash
cd /app && python3 -c "
import torch
def stats(name, pts):
    flat = pts.reshape(-1,4)
    print('====', name, '====')
    for i,ch in enumerate(['x','y','vel','aoa']):
        c = flat[:,i]
        print(f'  {ch:4s} min={c.min():.4f} max={c.max():.4f} mean={c.mean():.4f} std={c.std():.4f}')
    # per-case velocity and aoa (broadcast) -> take point 0
    vel = pts[:,0,2]; aoa = pts[:,0,3]
    print('  per-case vel: min=%.4f max=%.4f'%(vel.min(),vel.max()))
    print('  per-case aoa: min=%.4f max=%.4f (rad), deg min=%.3f max=%.3f'%(aoa.min(),aoa.max(), aoa.min()*57.2958, aoa.max()*57.2958))

for split in ['train','val','public_test']:
    p = torch.load(f'data/{split}/split.pt', weights_only=True)
    stats(split, p['points'])
"
output
==== train ====
  x    min=-0.0070 max=1.0000 mean=0.3835 std=0.3956
  y    min=-0.0997 max=0.1627 mean=0.0079 std=0.0335
  vel  min=31.2830 max=74.9240 mean=52.9737 std=12.7859
  aoa  min=-0.0862 max=0.2565 mean=0.0764 std=0.0956
  per-case vel: min=31.2830 max=74.9240
  per-case aoa: min=-0.0862 max=0.2565 (rad), deg min=-4.940 max=14.697
==== val ====
  x    min=-0.0033 max=1.0000 mean=0.3846 std=0.3959
  y    min=-0.0939 max=0.1366 mean=0.0078 std=0.0323
  vel  min=31.4680 max=74.1620 mean=54.9773 std=11.3969
  aoa  min=-0.0836 max=0.2512 mean=0.0799 std=0.0947
  per-case vel: min=31.4680 max=74.1620
  per-case aoa: min=-0.0836 max=0.2512 (rad), deg min=-4.790 max=14.393
==== public_test ====
  x    min=-0.0055 max=1.0000 mean=0.3761 std=0.3946
  y    min=-0.0961 max=0.1528 mean=0.0088 std=0.0346
  vel  min=75.0300 max=81.5930 mean=78.2086 std=1.9658
  aoa  min=-0.0857 max=0.2582 mean=0.0757 std=0.0961
  per-case vel: min=75.0300 max=81.5930
  per-case aoa: min=-0.0857 max=0.2582 (rad), deg min=-4.910 max=14.794
This is the key insight for the task. Let me confirm: - Train velocity: 31.28 – 74.92 m/s - Val velocity: 31.47 – 74.16 m/s - Public test velocity: **75.03 – 81.59 m/s** , entirely ABOVE the training range! So the test set is a pure extrapolation in velocity. The angle of attack ranges are similar across all splits. This is a classic extrapolation problem. The evaluation (hidden) set is described as "higher-speed, higher-Reynolds end" so the velocity is higher than training (75-81+ m/s, maybe higher). The key physics insight: the force coefficients C_D and C_L. In aerodynamics, force coefficients are *defined* to be roughly independent of velocity (they're normalized by dynamic pressure 0.5*rho*V^2*A). But in RANS simulations they depend on Reynolds number (which scales with velocity) and angle of attack. So C_D and C_L have a weak dependence on velocity through Reynolds number effects, but primarily depend on airfoil shape and angle of attack. Wait , but this is the crux. Let me check the relationship between targets and velocity. If C_D and C_L are nearly velocity-independent (depend mostly on shape + aoa), then a model that doesn't extrapolate badly in velocity would do well. The danger is that a naive model keys off the velocity channel and then extrapolates poorly. Let me look at the distribution of targets and their correlation with velocity and aoa. Let me understand the AirfRANS dataset. It's a known dataset (Bonnet et al. 2022, NeurIPS). The force coefficients are drag and lift coefficients. In AirfRANS, the inlet velocity ranges and angle of attack ranges... The scarce/full regime. The drag coefficient C_D is typically small (~0.01-0.1) and lift C_L is larger (~ -0.5 to 1.5 or so). Let me examine the targets.
I can already see the central challenge clearly. Let me quantify the target distributions and how the targets relate to velocity and angle of attack.
bash
cd /app && python3 -c "
import torch
for split in ['train','val']:
    p = torch.load(f'data/{split}/split.pt', weights_only=True)
    t = p['targets']
    print('====', split, '====')
    for i,name in enumerate(['C_D','C_L']):
        c=t[:,i]
        print(f'  {name}: min={c.min():.5f} max={c.max():.5f} mean={c.mean():.5f} std={c.std():.5f}')
    # correlations with vel and aoa
    vel = p['points'][:,0,2]; aoa = p['points'][:,0,3]
    import numpy as np
    for i,name in enumerate(['C_D','C_L']):
        c=t[:,i]
        cv=np.corrcoef(c.numpy(), vel.numpy())[0,1]
        ca=np.corrcoef(c.numpy(), aoa.numpy())[0,1]
        print(f'  corr({name},vel)={cv:.3f}  corr({name},aoa)={ca:.3f}')
"
output
==== train ====
  C_D: min=0.00727 max=0.04595 mean=0.01276 std=0.00510
  C_L: min=-0.53363 max=1.85012 mean=0.65962 std=0.57620
  corr(C_D,vel)=-0.154  corr(C_D,aoa)=0.739
  corr(C_L,vel)=-0.022  corr(C_L,aoa)=0.943
==== val ====
  C_D: min=0.00756 max=0.03459 mean=0.01268 std=0.00533
  C_L: min=-0.48027 max=1.80035 mean=0.67952 std=0.59777
  corr(C_D,vel)=-0.298  corr(C_D,aoa)=0.806
  corr(C_L,vel)=-0.102  corr(C_L,aoa)=0.939
This confirms the physics. The force coefficients depend primarily on angle of attack (and airfoil shape), and only weakly on velocity: - corr(C_L, aoa) = 0.94 , very strong - corr(C_L, vel) = -0.02 to -0.1 , very weak - corr(C_D, aoa) = 0.74-0.81 , strong - corr(C_D, vel) = -0.15 to -0.3 , weak-moderate So the coefficients are dominated by shape and aoa. The velocity has a weak effect (through Reynolds number , higher velocity → higher Re → lower skin friction drag coefficient, hence the negative correlation of C_D with velocity). The extrapolation concern: the test set has velocity 75-82 m/s, above the training max of 75. So if the model learns a spurious strong dependence on velocity, it'll extrapolate poorly. But since the true dependence on velocity is weak, the main risk is: 1. The model overfits to velocity as a feature and extrapolates wildly. 2. The standardization of velocity: in training, velocity is standardized with mean ~53 and std ~12.8. At test, velocity ~78 → standardized value ~ (78-53)/12.8 ≈ 2.0, which is outside the training range of standardized values (which go from (31-53)/12.8 ≈ -1.7 to (75-53)/12.8 ≈ 1.7). So the network sees inputs beyond its training distribution in that channel. Key strategies: 1. **Handle the velocity channel carefully.** Since C_D has a real (Reynolds) dependence on velocity, we can't just drop it. But we want the model to extrapolate smoothly. 2. **Physics-informed approach**: The drag coefficient's dependence on Reynolds number is smooth and monotonic (decreasing). A linear or mild extrapolation in velocity is physically reasonable. Let me think about what matters for the metric. The primary metric is `mean_nrmse` (normalized RMSE, mean over the two targets), secondary `worst_nrmse` and `cd_nmae`. NRMSE , normalized RMSE. Normalized by what? Typically by the std or range of the true target, or by the mean. Let me think. For each target, NRMSE = RMSE / (normalization). Common: normalize by std of true values, or by range (max-min), or by mean of absolute. Given "mean_nrmse" averages the per-target NRMSE, and C_D and C_L have very different scales, normalization per-target is essential. Since I don't know the exact normalization, I should aim for low RMSE on both targets in a *relative* sense. The safest is to minimize relative error on each target. Predicting each target well in its own scale. Let me think about the normalization constant for NRMSE. It's probably normalized by the standard deviation of the ground truth targets over the eval set, or by the range. Either way, what matters is getting low RMSE relative to the natural scale of each coefficient. Let me design the training to minimize a balanced relative error. Actually, let me reconsider. Because the evaluation is on a hidden high-velocity set, and the key difficulty is extrapolation, the single most important thing is robust generalization to higher velocity. Let me think carefully about how to achieve that. Approach ideas: 1. **Reduce reliance on velocity magnitude**: Since the true coefficient dependence on velocity is weak, I could consider transforming the velocity feature to reduce extrapolation error. But C_D does depend on it via Reynolds, so I shouldn't zero it out. 2. **Normalize velocity in a way that extrapolates well.** For instance, instead of standardizing, the network would see smoother behavior. But fundamentally a neural net with GELU will extrapolate somehow. 3. **Data augmentation in velocity**: I can augment training data by creating synthetic higher-velocity cases. But I'd need to know how the targets change with velocity , which I don't precisely. However, physics says C_D and C_L are approximately velocity-invariant (at fixed aoa and shape). So one powerful augmentation: **perturb the velocity channel while keeping targets fixed.** This teaches the network that velocity has only a weak effect on the output, preventing it from extrapolating wildly. This directly encodes the physica …[truncated]
The physics is clear: the coefficients are dominated by angle of attack (and airfoil shape), with only a weak dependence on velocity. Yet the scored set lives entirely above the training velocity range (75–82 vs 31–75). This is the crux , a naive model that keys strongly on velocity will extrapolate badly. Let me quantify the velocity dependence and how much shape matters.
bash
cd /app && python3 -c "
import torch, numpy as np
p = torch.load('data/train/split.pt', weights_only=True)
t = p['targets'].numpy()
pts = p['points'].numpy()
vel = pts[:,0,2]; aoa = pts[:,0,3]
N = len(t)
# Linear regression of each target on [1, aoa, vel, aoa^2]
def fit(X, y):
    beta, res, *_ = np.linalg.lstsq(X, y, rcond=None)
    pred = X@beta
    ss_res = ((y-pred)**2).sum(); ss_tot=((y-y.mean())**2).sum()
    return beta, 1-ss_res/ss_tot
for i,name in enumerate(['C_D','C_L']):
    y=t[:,i]
    X1=np.column_stack([np.ones(N),aoa])
    X2=np.column_stack([np.ones(N),aoa,vel])
    X3=np.column_stack([np.ones(N),aoa,aoa**2,vel,vel**2, aoa*vel])
    print(name)
    print('  R2 aoa only       :', round(fit(X1,y)[1],3))
    print('  R2 aoa+vel        :', round(fit(X2,y)[1],3))
    print('  R2 quad aoa,vel   :', round(fit(X3,y)[1],3))
"
output
C_D
  R2 aoa only       : 0.546
  R2 aoa+vel        : 0.566
  R2 quad aoa,vel   : 0.766
C_L
  R2 aoa only       : 0.89
  R2 aoa+vel        : 0.89
  R2 quad aoa,vel   : 0.892
So for C_L, aoa alone explains 89% of the variance. The rest is shape. Velocity adds essentially nothing. For C_D, aoa+quadratic explains 77%. Shape explains the rest. The velocity channel adds some (0.546 → 0.566 linearly, and in the quadratic model vel^2 helps). So the drag has a real but modest dependence on velocity (Reynolds). The most important signal is aoa (for both) and shape (especially for C_D). Velocity is secondary. Let me also check: does the velocity dependence of C_D make physical sense (higher V → lower C_D)? Let me look more carefully by isolating. Actually let me estimate the partial effect of velocity on C_D while controlling for aoa and shape. This tells me how much the test-set higher velocities should shift C_D. Let me think about the overall strategy now. Let me design: 1. A robust PointNet training with: - Good normalization. - Augmentation: I'll test whether velocity augmentation helps generalization to higher velocity. Given corr is weak, randomizing velocity up to higher ranges (extrapolating the input) with fixed targets could teach velocity-invariance. But that would hurt the C_D Reynolds effect. A middle ground: augment velocity with *moderate* noise/scaling so the network sees higher velocities during training and learns a smooth, bounded response. Actually, here's a cleaner idea specific to this architecture and problem. The biggest extrapolation risk is the velocity input channel going out of distribution. Let me think about how to make the network's velocity response well-behaved: Option A: Extend the training velocity range by augmentation. Create synthetic samples where I scale the velocity channel up to ~85 m/s. For the target, I need to know how C_D, C_L change. Physical model: C_L ~ independent of V; C_D ~ weakly decreasing with Re. Over 75→82, a ~9% velocity increase → Re increase ~9%. Skin-friction drag coefficient scales roughly as Re^-0.2 (turbulent) so ~ -1.8% change in friction drag. That's tiny relative to C_D variations. So treating coefficients as velocity-invariant for augmentation introduces minimal error and buys huge extrapolation robustness. Let me verify the magnitude of the velocity effect on C_D empirically. I want to find near-duplicate cases (same airfoil shape, same aoa, different velocity) if any exist. Given 630 training cases across airfoil shapes and conditions, there might be repeated shapes at different velocities. Let me check by hashing the shape (x,y coords).
For C_L, angle of attack alone explains 89% of variance; velocity adds nothing. For C_D, shape and aoa dominate, with a modest velocity (Reynolds) contribution. Let me check whether the same airfoil shape appears at multiple velocities, which would let me measure the true velocity effect directly.
bash
cd /app && python3 -c "
import torch, numpy as np
p = torch.load('data/train/split.pt', weights_only=True)
pts = p['points'].numpy(); t=p['targets'].numpy()
# shape signature = rounded x,y coords
shapes = pts[:,:,:2].reshape(len(pts),-1)
# hash by rounding
import hashlib
sig = [hashlib.md5(np.round(s,5).tobytes()).hexdigest() for s in shapes]
from collections import defaultdict
groups=defaultdict(list)
for i,s in enumerate(sig): groups[s].append(i)
mult=[g for g in groups.values() if len(g)>1]
print('unique shapes:', len(groups), ' shapes with >1 case:', len(mult))
# distribution of group sizes
from collections import Counter
print('group size counts:', Counter(len(g) for g in groups.values()))
"
output
unique shapes: 630  shapes with >1 case: 0
group size counts: Counter({1: 630})
Each case has a unique shape , so every case is a different airfoil geometry (or at least different sampling). So I can't directly find same-shape-different-velocity pairs. The AirfRANS dataset has many airfoil shapes. Let me check the nearest-neighbor structure in shape space to estimate the velocity effect. Actually, this is getting complicated. Let me instead take a more principled modeling approach. Let me reconsider the whole approach. Given the strong physical priors: - C_L depends mostly on aoa and shape, negligibly on velocity. - C_D depends on aoa, shape, and weakly on velocity (Reynolds). The extrapolation is in velocity. The key is to not let the model produce crazy outputs when velocity exceeds training range. Strategy for robustness to velocity extrapolation: 1. **Velocity augmentation during training**: Randomly perturb/scale the per-case velocity channel (e.g., multiply by a factor in [0.9, 1.25] or add noise), keeping targets fixed. This: - Exposes the network to higher velocity values (up to ~75*1.25 ≈ 94 m/s, covering the test range 75-82). - Teaches the network that the target is approximately invariant to velocity, which matches the physics and prevents wild extrapolation. - The small real Reynolds effect on C_D will be slightly washed out, but that effect is tiny compared to C_D's variance from shape/aoa. Net win. 2. **Standardization choice for velocity**: Using the training mean/std is fine as long as augmentation widens the effective range. Let me reconsider: should I even keep the velocity channel at all for prediction? If I set it to a constant, the network can't use it. But C_D has a real velocity dependence (the quad model went 0.566 with vel vs 0.546 without , small). And more importantly, if the whole test set is at high velocity, and the true C_D is slightly lower there due to Reynolds... but we can't calibrate that from training data at those velocities. Keeping velocity with augmentation that includes the test range is the best bet: the model can still use velocity within reason. Actually, let me think even more carefully. The concern with augmentation that randomizes velocity with fixed targets: it forces ∂output/∂velocity ≈ 0. That's actually close to true (coefficients nearly velocity-invariant). The residual velocity dependence of C_D is weak and unlearnable in extrapolation. So making the model velocity-invariant is a reasonable, robust choice. It guarantees that at test time (velocity 75-82), the model behaves like it would at the top of the training range (75), which is the closest in-distribution behavior. That's exactly the safe extrapolation: "clamp" behavior to the nearest trained regime. Hmm, but if I make it fully velocity-invariant, then the model effectively predicts based on shape+aoa only. Let me check: is that enough? C_L R2 from aoa alone is 0.89, plus shape should push higher. C_D needs shape. The PointNet can extract shape. So a velocity-invariant model should do well. But wait , there's a subtlety. If the network becomes velocity-invariant, then at test time the prediction is whatever the shape+aoa imply, calibrated on the *full* training velocity range (31-75). If true test C_D is systematically a bit lower (higher Re), we'd have a small positive bias. But that bias is small and unavoidable. Alternatively, I could model the velocity trend and extrapolate it, but that's risky. Let me take the balanced approach: augment velocity with noise that extends somewhat beyond the training range (so the network sees 75-95), but NOT fully randomize , use moderate multiplicative jitter so the network retains a weak, smooth velocity response learned from data but is exposed to the test range. Actually, a cleaner and very robust method: augment velocity by sampling new velocity values and keep targets fixed. Let me just test empirically what works best via the val set. But here's the problem: the val set velocity range (31-75) is the SAME as train. So val does NOT te …[truncated]
Every case is a unique geometry, so I can't directly isolate the velocity effect from repeated shapes. Two important findings so far: 1. **C_L ≈ f(aoa, shape)**, essentially velocity-independent. 2. **C_D** depends on shape/aoa with only a weak velocity (Reynolds) effect. Critically, the standard `val` split shares the training velocity range, so **it does not test the extrapolation that actually matters**. Let me check compute and then build a proper extrapolation validation.
bash
cd /app && python3 -c "
import torch, time
print('torch', torch.__version__, 'cuda', torch.cuda.is_available())
print('cpu threads', torch.get_num_threads())
import os; print('cpus', os.cpu_count())
# quick timing of a forward/backward
import sys; sys.path.insert(0,'.')
import json
cfg=json.load(open('task_config.json'))
from candidate_model import build_model
m=build_model(cfg)
x=torch.randn(32,256,4)
t=time.time()
for _ in range(20):
    y=m(x); y.sum().backward()
print('20 fwd/bwd bs32 on cpu: %.3fs'%(time.time()-t))
n=sum(p.numel() for p in m.parameters()); print('params', n)
"
output
torch 2.5.1+cu124 cuda False
cpu threads 16
cpus 16
20 fwd/bwd bs32 on cpu: 1.595s
params 83842
No GPU, CPU only with 16 threads. The model is tiny (84k params). 20 fwd/bwd of bs32 take 1.6s, so ~0.08s per batch. With 630 samples, ~20 batches/epoch → 1.6s/epoch. 40 epochs → ~64s. That's fine. I can do many experiments. Let me even do more epochs. Actually the batchnorm in the encoder operates over (B, C, P) with P=256 points, so effective batch for BN stats is B*P = 32*256 = 8192 , plenty. Good, BN is stable. Let me now build the experimentation harness. Key design decisions to test: 1. Augmentation: - velocity jitter (multiplicative/additive), strength - geometry jitter (small xy noise) - point dropout/resampling 2. Normalization of velocity (standard vs robust). 3. Loss: MSE vs Huber/SmoothL1 in standardized space; per-target weighting. 4. Schedule: cosine, epochs. 5. Ensembling (multiple seeds/ bagging). Local extrapolation validation: split train by velocity. Let me define: - pseudo_train = velocity < 65 (covers low-mid) - pseudo_test = velocity >= 65 (high) But better to mimic the actual gap. Test is above max train (75). So in pseudo setup, train on velocity < some threshold T, test on velocity >= T, where the test portion is entirely above the train portion , a true extrapolation. Let me pick T so pseudo_test is the top ~20%. Let me check the velocity distribution to pick T.
No GPU, but the model is tiny (84k params, ~1.6s/epoch on CPU), so I can run many experiments. Let me look at the velocity distribution to design a realistic extrapolation holdout.
bash
cd /app && python3 -c "
import torch, numpy as np
p = torch.load('data/train/split.pt', weights_only=True)
vel = p['points'][:,0,2].numpy()
print('quantiles of train velocity:')
for q in [0,10,25,50,75,80,85,90,95,100]:
    print(f'  {q:3d}%: {np.percentile(vel,q):.2f}')
# how many above various thresholds
for T in [60,63,65,67,70]:
    print(f'  vel>={T}: {(vel>=T).sum()} cases')
"
output
quantiles of train velocity:
    0%: 31.28
   10%: 35.42
   25%: 41.74
   50%: 53.27
   75%: 64.14
   80%: 66.60
   85%: 68.00
   90%: 70.35
   95%: 72.63
  100%: 74.92
  vel>=60: 217 cases
  vel>=63: 173 cases
  vel>=65: 148 cases
  vel>=67: 117 cases
  vel>=70: 70 cases
Good. I'll design the pseudo-extrapolation validation: train on vel < 63, test on vel >= 63. That's ~457 train / 173 test, and the test is entirely above the train max (63). The gap between train-max (63) and test-range (63-75) mimics the real train(→75)/test(75-82) shift: the test extends ~19% above train max (75→82 is ~9%, 63→75 is ~19%). Actually the real shift: train max 75, test max 82 → test extends to 1.09x. My pseudo: train max 63, test to 75 → 1.19x. A bit more aggressive, which is good for being conservative. Actually, let me make the pseudo-test mimic the real ratio better AND be a solid test. Let me use two pseudo-test configs to be robust: - Config A: train vel<65, test vel in [65,75] (test up to 1.15x train max) - I'll primarily use one but can check both. Let me also consider that the real test goes to 82 which is 1.09x of 75. And evaluation "reaches beyond the inlet velocities present in training" and is "higher-speed, higher-Reynolds end". The hidden set might go even higher than public_test's 82. Hard to know. I'll aim for robustness. Let me build the harness now. I'll write a module `exp.py` with a configurable train/eval function, using the pseudo-extrapolation split, returning NRMSE metrics. Let me define NRMSE. I'll compute per-target: nrmse_i = sqrt(mean((pred-true)^2)) / std(true) where std is over the eval set. Also compute a range-normalized version. And report MAE-based. I'll track mean_nrmse (avg of the two per-target, using std normalization) since that's the primary metric name. Let me also compute the range-normalized version to be safe. I'll look at both; they should be correlated. Actually, I realize the normalization constant for NRMSE in the hidden evaluation uses the hidden set's true targets, which I don't have. But relative comparisons between my strategies are what matter for selection, and those are robust to the exact normalization constant. I'll use std-normalization computed on the pseudo-test targets. Let me write the harness. Let me think about what features/augmentations to implement: 1. `vel_aug`: during training, multiply per-case velocity by factor ~ U(lo, hi) or add noise. This both exposes higher velocities and reduces velocity sensitivity. 2. `geom_jitter`: add small Gaussian noise to x,y coordinates (std ~0.002-0.005) for regularization. 3. `point_resample`: randomly resample/shuffle points (PointNet is permutation invariant due to maxpool, so shuffling does nothing). Could do random subsampling but P is fixed at 256 for the model input... the model expects 256 points? Actually maxpool works on any number of points, but the contract says 256. I'll keep 256. Could drop+duplicate points as augmentation. Minor. 4. `targ_transform`: predict standardized targets (z-score). Keep. Let me also consider a totally different, powerful idea: **reduce the velocity channel's influence by design**. Since the net standardizes velocity, and at test velocity is ~+2 std, the encoder's Conv1d on the velocity channel will produce activations beyond training range. With augmentation exposing that range, it's fine. Let me just implement and test. Let me write exp.py. I'll structure: - load train split, build pseudo split by velocity threshold. - standardize using pseudo_train stats (important: mimic real scenario where we standardize using training data only). - train with config. - eval on pseudo_test, return metrics. For the final model, I'll train on ALL labeled data (train + val) with the chosen config, using standardization computed from that combined data, then save. Let me write it. One more consideration: model selection / early stopping. Since val doesn't test extrapolation, selecting the checkpoint by val loss might not reflect extrapolation performance. But I can't use the real test. For the final model, I'll use a fixed schedule (cosine) and train for a chosen number of epochs determined from the pseudo-extrapolation experiments, then take the final (or EMA) weights. E …[truncated]
No GPU, but the model is tiny so experimentation is cheap. My plan: build a **velocity-based extrapolation holdout** (train on low velocities, test on the highest) to locally measure what actually matters , generalization beyond the training velocity range. Let me write a configurable experiment harness.
str_replace_based_edit_tool
command: create
path: /app/exp.py
file_text: """Experiment harness for the airfoil force-coefficient task.

Core idea: the scored set lives ABOVE the training velocity range, but the
provided val split shares the training range. So we build a *velocity
extrapolation* holdout from the training data itself (train on low velocities,
evaluate on the highest) to measure the thing that actually matters.
"""
from __future__ import annotations
import json, os, sys, copy, math
from pathlib import Path
import numpy as np
import torch
import torch.nn.functional as F

APP_DIR = Path('/app')
sys.path.insert(0, str(APP_DIR))
from candidate_model import build_model
from dataset import load_split

CFG = json.load(open(APP_DIR / 'task_config.json'))


def load_all():
    ptr, ttr = load_split(APP_DIR / 'data' / 'train')
    pva, tva = load_split(APP_DIR / 'data' / 'val')
    return ptr, ttr, pva, tva


def standardize_stats(points, targets):
    flat = points.reshape(-1, points.shape[-1])
    fmean = flat.mean(0); fstd = flat.std(0).clamp_min(1e-8)
    tmean = targets.mean(0); tstd = targets.std(0).clamp_min(1e-8)
    return fmean, fstd, tmean, tstd


def nrmse_metrics(pred, true):
    """pred,true: [N,2] physical units. Returns dict of per-target nrmse etc."""
    pred = pred.numpy() if torch.is_tensor(pred) else pred
    true = true.numpy() if torch.is_tensor(true) else true
    out = {}
    names = ['cd', 'cl']
    nrmse_std = []; nrmse_rng = []
    for i, n in enumerate(names):
        err = pred[:, i] - true[:, i]
        rmse = np.sqrt((err ** 2).mean())
        std = true[:, i].std(); rng = true[:, i].max() - true[:, i].min()
        out[f'{n}_rmse'] = rmse
        out[f'{n}_nrmse_std'] = rmse / (std + 1e-12)
        out[f'{n}_nrmse_rng'] = rmse / (rng + 1e-12)
        out[f'{n}_mae'] = np.abs(err).mean()
        out[f'{n}_nmae'] = np.abs(err).mean() / (np.abs(true[:, i]).mean() + 1e-12)
        nrmse_std.append(rmse / (std + 1e-12)); nrmse_rng.append(rmse / (rng + 1e-12))
    out['mean_nrmse_std'] = float(np.mean(nrmse_std))
    out['worst_nrmse_std'] = float(np.max(nrmse_std))
    out['mean_nrmse_rng'] = float(np.mean(nrmse_rng))
    return out


def augment(xb_phys, cfg, fmean, fstd):
    """xb_phys: [B,256,4] physical units. Returns standardized, augmented batch."""
    B = xb_phys.shape[0]
    x = xb_phys.clone()
    # velocity augmentation (per-case multiplicative)
    vfac = cfg.get('vel_mult', 0.0)
    if vfac > 0:
        f = torch.empty(B, 1).uniform_(1.0 - vfac, 1.0 + cfg.get('vel_mult_hi', vfac))
        x[:, :, 2] = x[:, :, 2] * f
    vadd = cfg.get('vel_add', 0.0)
    if vadd > 0:
        x[:, :, 2] = x[:, :, 2] + torch.randn(B, 1) * vadd
    # geometry jitter on x,y
    gj = cfg.get('geom_jitter', 0.0)
    if gj > 0:
        x[:, :, :2] = x[:, :, :2] + torch.randn(B, 256, 2) * gj
    # aoa jitter
    aj = cfg.get('aoa_jitter', 0.0)
    if aj > 0:
        x[:, :, 3] = x[:, :, 3] + torch.randn(B, 1) * aj
    xs = (x - fmean.view(1, 1, -1)) / fstd.view(1, 1, -1)
    return xs


def train_model(xtr_phys, ytr, cfg, fmean, fstd, tmean, tstd, seed=0, verbose=False):
    torch.manual_seed(seed); np.random.seed(seed)
    device = 'cpu'
    model = build_model(CFG).to(device)
    ys = (ytr - tmean.view(1, -1)) / tstd.view(1, -1)
    epochs = cfg.get('epochs', 80)
    bs = cfg.get('bs', 32)
    lr = cfg.get('lr', 1e-3)
    wd = cfg.get('wd', 1e-4)
    opt = torch.optim.Adam(model.parameters(), lr=lr, weight_decay=wd)
    n = xtr_phys.shape[0]
    sched_type = cfg.get('sched', 'cosine')
    steps_per = max(1, math.ceil(n / bs))
    total_steps = epochs * steps_per
    def lr_at(step):
        warm = cfg.get('warmup_steps', 0)
        if step < warm:
            return lr * (step + 1) / warm
        if sched_type == 'cosine':
            prog = (step - warm) / max(1, total_steps - warm)
            return cfg.get('lr_min', 1e-5) + 0.5 * (lr - cfg.get('lr_min', 1e-5)) * (1 + math.cos(math.pi * prog))
        return lr
    tw = cfg.get(
…[truncated]
output
New file created successfully at /app/exp.py
Now let me write a driver script that runs the pseudo-extrapolation experiment for a given config. Let me first establish a baseline: train with the default settings (no augmentation, MSE, 40 epochs) on the pseudo-train (vel<63) and evaluate on pseudo-test (vel>=63). Then compare to augmented versions. Let me create the driver.
Now let me build a driver that runs configs on the velocity-extrapolation holdout and reports metrics, then establish the baseline.
str_replace_based_edit_tool
command: create
path: /app/run_exp.py
file_text: from __future__ import annotations
import sys, json, time
import numpy as np
import torch
from exp import (load_all, standardize_stats, train_model, recompute_bn,
                 predict, nrmse_metrics)


def pseudo_split(points, targets, thresh):
    vel = points[:, 0, 2]
    tr = vel < thresh
    te = vel >= thresh
    return points[tr], targets[tr], points[te], targets[te]


def run(cfg, thresh=63.0, seeds=(0,), which='final', recompute=True, verbose=True):
    ptr_all, ttr_all, pva, tva = load_all()
    xtr, ytr, xte, yte = pseudo_split(ptr_all, ttr_all, thresh)
    fmean, fstd, tmean, tstd = standardize_stats(xtr, ytr)
    preds = []
    for seed in seeds:
        res, _ = train_model(xtr, ytr, cfg, fmean, fstd, tmean, tstd, seed=seed)
        state = res[which] if which in res else res['final']
        if recompute and which in ('ema', 'swa'):
            state = recompute_bn(state, xtr, fmean, fstd, cfg)
        p = predict(state, xte, fmean, fstd, tmean, tstd)
        preds.append(p)
    pred = torch.stack(preds).mean(0)
    m = nrmse_metrics(pred, yte)
    if verbose:
        print(f"  [thresh={thresh} which={which} seeds={len(seeds)}] "
              f"mean_nrmse_std={m['mean_nrmse_std']:.4f} "
              f"cd_nrmse={m['cd_nrmse_std']:.4f} cl_nrmse={m['cl_nrmse_std']:.4f} "
              f"worst={m['worst_nrmse_std']:.4f} cd_nmae={m['cd_nmae']:.4f}")
    return m


if __name__ == '__main__':
    name = sys.argv[1] if len(sys.argv) > 1 else 'baseline'
    configs = {
        'baseline': dict(epochs=40, lr=1e-3, wd=1e-4, sched='const', loss='mse'),
        'baseline_cos': dict(epochs=80, lr=1e-3, wd=1e-4, sched='cosine', loss='mse'),
    }
    cfg = configs[name]
    t = time.time()
    run(cfg, thresh=63.0, seeds=(0, 1, 2))
    print('  time %.1fs' % (time.time() - t))
output
New file created successfully at /app/run_exp.py
bash
cd /app && echo "=== baseline (const lr, MSE, 40ep, no aug) ===" && python3 run_exp.py baseline && echo "=== baseline cosine 80ep ===" && python3 run_exp.py baseline_cos
output
=== baseline (const lr, MSE, 40ep, no aug) ===
  [thresh=63.0 which=final seeds=3] mean_nrmse_std=0.1713 cd_nrmse=0.1939 cl_nrmse=0.1487 worst=0.1939 cd_nmae=0.0494
  time 57.1s
=== baseline cosine 80ep ===
  [thresh=63.0 which=final seeds=3] mean_nrmse_std=0.1227 cd_nrmse=0.1414 cl_nrmse=0.1040 worst=0.1414 cd_nmae=0.0342
  time 102.5s
The cosine schedule with 80 epochs already significantly improves over the baseline (0.171 → 0.123 mean_nrmse). Good. Now let me test the key lever: velocity augmentation, which should help extrapolation. Let me also test geometry jitter, EMA/SWA, Huber loss, and target weighting. Let me create a more comprehensive experiment sweep. I'll add configs and run them. Let me be efficient and run several configs in one script, reusing 3 seeds. Let me think about the velocity augmentation. The pseudo-test is vel in [63, 75]. The pseudo-train is vel in [31, 63]. To extrapolate to [63,75], multiplicative vel augmentation with factor up to 75/63 ≈ 1.19 would expose the model to the test range. Let me try vel_mult with asymmetric range: down 0.1, up to e.g. 0.25-0.35. Using vel_mult=0.1 and vel_mult_hi=0.3 means factor in [0.9, 1.3]. At train max 63, that reaches 63*1.3 = 81.9. Good coverage. But remember the real scenario: train max 75, test to 82 (1.09x) or higher. For the final model I'd want vel augmentation reaching ~1.2-1.3x of 75 = 90-97. So the augmentation factor should be generous. Let me test several vel augmentation strengths on the pseudo split. Let me build a sweep runner.
The cosine schedule with more epochs already helps a lot (0.171 → 0.123). Now the key lever: **velocity augmentation** to handle the extrapolation. Let me sweep several ideas together.
str_replace_based_edit_tool
command: create
path: /app/sweep.py
file_text: from __future__ import annotations
import time, itertools
import numpy as np
from run_exp import run

BASE = dict(epochs=80, lr=1e-3, wd=1e-4, sched='cosine', loss='mse')

def cfg(**kw):
    c = dict(BASE); c.update(kw); return c

EXPS = {
  'cos80':            cfg(),
  'vel_m10_30':       cfg(vel_mult=0.10, vel_mult_hi=0.30),
  'vel_m15_40':       cfg(vel_mult=0.15, vel_mult_hi=0.40),
  'vel_m20_50':       cfg(vel_mult=0.20, vel_mult_hi=0.50),
  'geom002':          cfg(geom_jitter=0.002),
  'vel_m15_40_g002':  cfg(vel_mult=0.15, vel_mult_hi=0.40, geom_jitter=0.002),
  'huber':            cfg(loss='huber', huber_beta=1.0),
  'vel_m15_40_huber': cfg(vel_mult=0.15, vel_mult_hi=0.40, loss='huber', huber_beta=1.0),
}

if __name__ == '__main__':
    import sys
    keys = sys.argv[1:] if len(sys.argv) > 1 else list(EXPS)
    for k in keys:
        t = time.time()
        print(f'### {k}')
        run(EXPS[k], thresh=63.0, seeds=(0, 1, 2))
        print('   (%.1fs)' % (time.time() - t))
output
New file created successfully at /app/sweep.py
bash
cd /app && python3 sweep.py vel_m10_30 vel_m15_40 vel_m20_50 2>&1
output
### vel_m10_30
  [thresh=63.0 which=final seeds=3] mean_nrmse_std=0.1599 cd_nrmse=0.2634 cl_nrmse=0.0563 worst=0.2634 cd_nmae=0.0503
   (103.8s)
### vel_m15_40
  [thresh=63.0 which=final seeds=3] mean_nrmse_std=0.1952 cd_nrmse=0.3377 cl_nrmse=0.0528 worst=0.3377 cd_nmae=0.0624
   (87.3s)
### vel_m20_50
  [thresh=63.0 which=final seeds=3] mean_nrmse_std=0.2199 cd_nrmse=0.3889 cl_nrmse=0.0509 worst=0.3889 cd_nmae=0.0730
   (102.7s)
Interesting and important result! Velocity augmentation: - Dramatically IMPROVES C_L extrapolation: cl_nrmse drops from 0.104 (cos80) to 0.053-0.051. This confirms C_L is velocity-invariant, and making the model velocity-invariant helps C_L a lot. - But it HURTS C_D: cd_nrmse rises from 0.141 (cos80) to 0.26-0.39. This means C_D DOES have a real velocity dependence that the model was using, and washing it out hurts. So there's a tension: velocity-invariance helps C_L but hurts C_D. This makes physical sense: - C_L: velocity-invariant, so augmentation helps by preventing spurious velocity use. - C_D: has Reynolds dependence, so the model legitimately uses velocity; washing it out via heavy augmentation removes useful signal. But wait , at extrapolation, does the model's learned velocity dependence actually generalize correctly to the higher range? Let me reconsider. Actually cd_nrmse WITHOUT aug (cos80) was 0.141. The baseline cosine at thresh 63 extrapolating to [63,75] got cd_nrmse 0.141. With vel aug it got WORSE (0.26+). So for C_D, the model without aug extrapolated its velocity dependence reasonably. Hmm. Wait, but this is the pseudo-test where the true C_D at higher velocity is LOWER (Reynolds). The no-aug model learned "higher vel → lower C_D" and extrapolated that trend, getting the test right-ish. The aug model learned "C_D independent of vel" → predicts higher C_D than truth at high vel → worse. But here's the subtlety for the REAL test: the real test is at vel 75-82, beyond train max 75. The no-aug model would extrapolate its learned velocity trend. Is that trend reliable that far out? In my pseudo-experiment, extrapolating from [31,63] to [63,75] (a wide extrapolation), the no-aug model's C_D trend held reasonably (cd_nrmse 0.141). That's actually evidence that the learned velocity dependence of C_D extrapolates OK, at least modestly. So maybe I should NOT apply heavy velocity augmentation to C_D, but DO want velocity-invariance for C_L. But the model is shared (one network, two outputs). I can't easily make it velocity-invariant for one output and not the other. Options: 1. **Targeted augmentation via a mix**: Use a moderate velocity augmentation that helps C_L without destroying C_D too much. But the single model shares features. 2. **Per-target loss weighting** combined with augmentation: doesn't resolve the tension. 3. Think about what the AGGREGATE metric does. mean_nrmse = (cd_nrmse + cl_nrmse)/2. - cos80: (0.141 + 0.104)/2 = 0.123 - vel_m10_30: (0.263 + 0.056)/2 = 0.160 So no-aug is better on the mean because C_D degradation outweighs C_L gain. Hmm. But wait , maybe there's a smarter way. What if velocity augmentation is *partial* , i.e., I keep some cases un-augmented and augment others? Or use small vel noise rather than large multiplicative? Actually, let me reconsider the C_D extrapolation. The issue is that augmentation with FIXED targets tells the model "C_D doesn't change with velocity", which is wrong for C_D. What if instead I augment velocity AND adjust the C_D target according to a fitted Reynolds trend? That would teach the correct velocity dependence and extend the range. But estimating the trend is error-prone. Alternatively , and this is cleaner , maybe the real issue is that the no-aug model does fine on C_D extrapolation but poorly on C_L because it spuriously uses velocity for C_L. Let me verify: in cos80, cl_nrmse=0.104. With aug, cl_nrmse=0.053. So yes, the no-aug model spuriously keys C_L off velocity and degrades. Let me reconsider the whole thing. What if I decouple: the model has access to velocity. For C_L, velocity should be ignored. For C_D, velocity matters. A single shared network must balance. Let me think about a light velocity augmentation: small multiplicative jitter (e.g., ±5-10%) plus exposure. Let me test a gentler aug: vel_mult=0.05, vel_mult_hi=0.15. Also test additive noise. Actually, let me reconsider even more carefully. Let me look at what driv …[truncated]
Very informative. Velocity augmentation **helps C_L** (0.104→0.053, confirming C_L is velocity-invariant) but **hurts C_D** (0.141→0.26+). This reveals the real tension: C_D has a genuine Reynolds (velocity) dependence that the model legitimately uses, while C_L does not. Washing out velocity with fixed targets teaches "C_D independent of velocity," which is wrong. The cleaner fix is to augment velocity while **correcting the C_D target along a Reynolds power law**. Let me estimate that exponent from the data.
bash
cd /app && python3 -c "
import torch, numpy as np
p = torch.load('data/train/split.pt', weights_only=True)
t = p['targets'].numpy(); pts=p['points'].numpy()
vel=pts[:,0,2]; aoa=pts[:,0,3]
cd=t[:,0]; cl=t[:,1]
N=len(cd)
def fit(X,y):
    beta,*_=np.linalg.lstsq(X,y,rcond=None); pred=X@beta
    r2=1-((y-pred)**2).sum()/((y-y.mean())**2).sum(); return beta,r2
# log(cd) ~ 1, aoa, aoa^2, aoa^3, log(vel)
X=np.column_stack([np.ones(N),aoa,aoa**2,aoa**3,np.log(vel)])
b,r2=fit(X,np.log(cd))
print('log(cd) model R2=%.3f, coef log(vel)=%.3f'%(r2,b[-1]))
# cl ~ aoa poly + log vel
X2=np.column_stack([np.ones(N),aoa,aoa**2,aoa**3,np.log(vel)])
b2,r2b=fit(X2,cl)
print('cl model R2=%.3f, coef log(vel)=%.4f'%(r2b,b2[-1]))
# also linear vel coefficient on cd controlling aoa
X3=np.column_stack([np.ones(N),aoa,aoa**2,aoa**3,vel])
b3,r3=fit(X3,cd); print('cd linear-vel coef=%.3e per m/s (cd mean %.4f)'%(b3[-1],cd.mean()))
"
output
log(cd) model R2=0.818, coef log(vel)=-0.209
cl model R2=0.892, coef log(vel)=-0.0155
cd linear-vel coef=-5.982e-05 per m/s (cd mean 0.0128)
Excellent. This is a clean, physically-sensible result: - log(C_D) ~ -0.209 * log(vel) controlling for aoa. So C_D ∝ vel^(-0.209). That's essentially the turbulent skin-friction Reynolds exponent (~ -0.2)! Beautiful confirmation. - C_L: log(vel) coefficient is -0.0155, essentially negligible (C_L nearly velocity-invariant). So I have a physics-based law: - C_D scales as vel^(-0.21) - C_L is ~constant in vel. This gives me a powerful augmentation: when I multiply velocity by factor f, I should multiply C_D by f^(-0.209) and keep C_L unchanged. This teaches the model the CORRECT velocity dependence AND extends the velocity range for extrapolation. This should help BOTH: - C_L: becomes velocity-invariant (helps, as shown). - C_D: learns the correct Reynolds trend and sees the extended range, so extrapolation to high velocity is physically correct. Even better , this physics law itself could be used as a direct correction. But let me incorporate it into augmentation first since it fits the learned-surrogate framing and the fixed architecture. Let me implement `vel_reynolds` augmentation: sample factor f, set vel *= f, cd_target *= f^(exponent), cl unchanged. The exponent default -0.209. Actually, I need to be careful: the target is standardized. The augmentation modifies the PHYSICAL target, so I should apply the correction in physical space before standardizing. Let me refactor train_model to augment targets too. Let me update the augment function to also return adjusted targets. Let me modify exp.py. Let me think about the exponent. The fit gave -0.209 globally. This is robust (matches theory). I'll use -0.21. But let me also allow tuning. Also, I should double check: is the relationship better modeled per-case? The exponent -0.209 is an average. Some airfoils may differ. But -0.21 is a solid physics-based estimate and matches turbulent flat plate Cf ∝ Re^-0.2. Good. Now, crucially, this correction also lets me do something at INFERENCE if I wanted (e.g., predict at a reference velocity and rescale), but the task requires reading predictions straight from the model output. So I'll bake the physics into training via augmentation so the single model learns it. Let me refactor the augment to handle target correction. Let me rewrite the relevant part of exp.py.
A beautifully clean result: **C_D ∝ velocity^(−0.21)** (controlling for aoa), which is exactly the turbulent skin-friction Reynolds exponent (~−0.2), while **C_L's velocity exponent is ≈ −0.015 (negligible)**. This gives me a physics-grounded augmentation: when I scale velocity by factor *f*, I should scale the C_D target by *f^(−0.21)* and leave C_L unchanged. This teaches the model the *correct* Reynolds trend while extending the velocity range for extrapolation , resolving the C_D/C_L tension. Let me implement it.
str_replace_based_edit_tool
command: str_replace
path: /app/exp.py
old_str: def augment(xb_phys, cfg, fmean, fstd):
    """xb_phys: [B,256,4] physical units. Returns standardized, augmented batch."""
    B = xb_phys.shape[0]
    x = xb_phys.clone()
    # velocity augmentation (per-case multiplicative)
    vfac = cfg.get('vel_mult', 0.0)
    if vfac > 0:
        f = torch.empty(B, 1).uniform_(1.0 - vfac, 1.0 + cfg.get('vel_mult_hi', vfac))
        x[:, :, 2] = x[:, :, 2] * f
    vadd = cfg.get('vel_add', 0.0)
    if vadd > 0:
        x[:, :, 2] = x[:, :, 2] + torch.randn(B, 1) * vadd
    # geometry jitter on x,y
    gj = cfg.get('geom_jitter', 0.0)
    if gj > 0:
        x[:, :, :2] = x[:, :, :2] + torch.randn(B, 256, 2) * gj
    # aoa jitter
    aj = cfg.get('aoa_jitter', 0.0)
    if aj > 0:
        x[:, :, 3] = x[:, :, 3] + torch.randn(B, 1) * aj
    xs = (x - fmean.view(1, 1, -1)) / fstd.view(1, 1, -1)
    return xs
new_str: def augment(xb_phys, yb_phys, cfg, fmean, fstd):
    """xb_phys:[B,256,4] physical, yb_phys:[B,2] physical (C_D,C_L).

    Returns (standardized augmented inputs, physical augmented targets).
    Velocity is scaled multiplicatively; the C_D target is corrected along a
    Reynolds power law  C_D *= f**cd_exp  (cd_exp~-0.21), C_L left unchanged.
    """
    B = xb_phys.shape[0]
    x = xb_phys.clone()
    y = yb_phys.clone()
    # velocity augmentation (per-case multiplicative) with Reynolds target fix
    vfac = cfg.get('vel_mult', 0.0)
    if vfac > 0:
        f = torch.empty(B).uniform_(1.0 - vfac, 1.0 + cfg.get('vel_mult_hi', vfac))
        x[:, :, 2] = x[:, :, 2] * f.view(B, 1)
        cd_exp = cfg.get('cd_exp', -0.21)
        y[:, 0] = y[:, 0] * f.pow(cd_exp)
        cl_exp = cfg.get('cl_exp', 0.0)
        if cl_exp != 0.0:
            y[:, 1] = y[:, 1] * f.pow(cl_exp)
    # geometry jitter on x,y
    gj = cfg.get('geom_jitter', 0.0)
    if gj > 0:
        x[:, :, :2] = x[:, :, :2] + torch.randn(B, 256, 2) * gj
    # aoa jitter
    aj = cfg.get('aoa_jitter', 0.0)
    if aj > 0:
        x[:, :, 3] = x[:, :, 3] + torch.randn(B, 1) * aj
    xs = (x - fmean.view(1, 1, -1)) / fstd.view(1, 1, -1)
    return xs, y
output
The file /app/exp.py has been edited successfully.
str_replace_based_edit_tool
command: str_replace
path: /app/exp.py
old_str:     ys = (ytr - tmean.view(1, -1)) / tstd.view(1, -1)
    epochs = cfg.get('epochs', 80)
new_str:     epochs = cfg.get('epochs', 80)
output
The file /app/exp.py has been edited successfully.
str_replace_based_edit_tool
command: str_replace
path: /app/exp.py
old_str:             idx = perm[s:s + bs]
            xb = augment(xtr_phys[idx], cfg, fmean, fstd)
            yb = ys[idx]
new_str:             idx = perm[s:s + bs]
            xb, yb_phys = augment(xtr_phys[idx], ytr[idx], cfg, fmean, fstd)
            yb = (yb_phys - tmean.view(1, -1)) / tstd.view(1, -1)
output
The file /app/exp.py has been edited successfully.
Now let me test the Reynolds-corrected velocity augmentation against the no-aug baseline, and sweep the augmentation strength.
bash
cd /app && python3 -c "
from run_exp import run
BASE=dict(epochs=80,lr=1e-3,wd=1e-4,sched='cosine',loss='mse')
def cfg(**kw):
    c=dict(BASE); c.update(kw); return c
exps={
 'no_aug':            cfg(),
 'reyn_m10_30':       cfg(vel_mult=0.10, vel_mult_hi=0.30, cd_exp=-0.21),
 'reyn_m15_40':       cfg(vel_mult=0.15, vel_mult_hi=0.40, cd_exp=-0.21),
 'reyn_m20_60':       cfg(vel_mult=0.20, vel_mult_hi=0.60, cd_exp=-0.21),
}
for k,c in exps.items():
    print('###',k)
    run(c, thresh=63.0, seeds=(0,1,2))
"
output
[stderr]
Shell command timed out.
Tool interaction exceeded 300 seconds.
bash
restart: true
output
<system>tool has been restarted.</system>
The runs take ~100s each, 4 of them = 400s > 300s timeout. I need to run in background and poll, or run fewer. Let me run in background with nohup and write results to a file. Let me also reduce to 2 seeds and set threads appropriately. Let me run experiments in the background to avoid timeouts.
The 4-config run exceeded the 300s limit. Let me run experiments in the background and poll the results file instead.
bash
cd /app && cat > runbg.py << 'EOF'
import sys, time, json
from run_exp import run
BASE=dict(epochs=80,lr=1e-3,wd=1e-4,sched='cosine',loss='mse')
def cfg(**kw):
    c=dict(BASE); c.update(kw); return c
ALL={
 'no_aug':        cfg(),
 'reyn_m10_30':   cfg(vel_mult=0.10, vel_mult_hi=0.30, cd_exp=-0.21),
 'reyn_m15_40':   cfg(vel_mult=0.15, vel_mult_hi=0.40, cd_exp=-0.21),
 'reyn_m20_60':   cfg(vel_mult=0.20, vel_mult_hi=0.60, cd_exp=-0.21),
 'reyn_m10_30_e0':cfg(vel_mult=0.10, vel_mult_hi=0.30, cd_exp=0.0),
}
keys=sys.argv[1:]
out=open('results.txt','a')
for k in keys:
    t=time.time()
    m=run(ALL[k], thresh=63.0, seeds=(0,1,2), verbose=False)
    line=f"{k:18s} mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f} worst={m['worst_nrmse_std']:.4f} cd_nmae={m['cd_nmae']:.4f} ({time.time()-t:.0f}s)"
    print(line); out.write(line+'\n'); out.flush()
out.close()
EOF
echo "written"
output
written
bash
cd /app && rm -f results.txt && export OMP_NUM_THREADS=16 && nohup python3 runbg.py no_aug reyn_m10_30 reyn_m15_40 reyn_m20_60 reyn_m10_30_e0 > sweep1.log 2>&1 &
echo "started pid $!"
output
started pid 16276
Let me wait and poll. Each run ~100s, 5 runs = ~500s. Let me poll periodically with short sleeps.
While that runs, let me set up a more realistic multi-threshold evaluation. The real test is only ~9% above the training max, but the hidden set could go higher, so I want to see how strategies behave as the extrapolation distance grows. Let me poll the first sweep.
bash
cd /app && sleep 240 && echo "--- results so far ---" && cat results.txt 2>/dev/null
output
--- results so far ---
no_aug             mean=0.1227 cd=0.1414 cl=0.1040 worst=0.1414 cd_nmae=0.0342 (98s)
reyn_m10_30        mean=0.1281 cd=0.2002 cl=0.0559 worst=0.2002 cd_nmae=0.0306 (112s)
Hmm. The Reynolds-corrected aug (reyn_m10_30) vs no_aug: - no_aug: mean=0.1227, cd=0.1414, cl=0.1040, cd_nmae=0.0342 - reyn_m10_30: mean=0.1281, cd=0.2002, cl=0.0559, cd_nmae=0.0306 So C_L improved massively (0.104→0.056), cd_nmae improved (0.0342→0.0306, so MAE on C_D is actually better!), but cd_nrmse got WORSE (0.141→0.200). Interesting , the cd_nmae (mean abs error normalized) improved while cd_nrmse (RMS) worsened. That means the aug model has lower typical/median C_D error but larger outliers (RMS dominated by worst cases). Why would RMS worsen while MAE improves? Possibly a few high-C_D cases (high drag, likely high aoa) get worse with aug. The velocity augmentation with Reynolds correction might be interfering with the high-drag regime. Or the extrapolation of C_D to the test velocity range. Let me wait for the rest and then dig in. The mean_nrmse_std is still slightly worse with aug (0.128 vs 0.123) because cd_nrmse dominates. But this is the pseudo-test at thresh=63 (aggressive 19% extrapolation). Let me see the stronger aug results and also test at thresh closer to real (70). Let me wait for more results.
bash
cd /app && sleep 200 && cat results.txt 2>/dev/null
output
no_aug             mean=0.1227 cd=0.1414 cl=0.1040 worst=0.1414 cd_nmae=0.0342 (98s)
reyn_m10_30        mean=0.1281 cd=0.2002 cl=0.0559 worst=0.2002 cd_nmae=0.0306 (112s)
reyn_m15_40        mean=0.1572 cd=0.2631 cl=0.0514 worst=0.2631 cd_nmae=0.0345 (111s)
reyn_m20_60        mean=0.1808 cd=0.3131 cl=0.0485 worst=0.3131 cd_nmae=0.0366 (112s)
So stronger velocity augmentation keeps helping C_L (down to 0.0485) but keeps hurting cd_nrmse (up to 0.313). The Reynolds correction didn't fully fix C_D. Let me understand why cd_nrmse gets worse with velocity aug even with the correct power law. Let me wait for the last run (reyn_m10_30_e0) and then investigate the C_D issue directly. Actually, I suspect the issue: the pseudo-test at thresh=63 has test cases at vel 63-75. The C_D RMS error is dominated by high-drag cases. Let me look at where the error concentrates. Actually, let me reconsider. The cd_nrmse increase with velocity aug is suspicious given the MAE improves. Let me think about what RMS vs MAE divergence means , a few large errors. Possibility: velocity augmentation scales velocity up to 1.3-1.6x. For low-velocity training cases (vel~31), scaling up by 1.6 → vel~50, still in range. For high-velocity training cases in pseudo-train (vel near 63), scaling up 1.6 → ~100, way beyond. The C_D correction f^-0.21: for f=1.6, that's 0.92, so C_D reduced by 8%. That's the correct physics. But maybe the problem is that augmenting creates input velocity values (up to ~100) far beyond even the test range (75), and with BatchNorm the statistics get distorted, OR the model spends capacity on a huge velocity range and underfits the actual test region. Let me reconsider: The goal metric weights cd_nrmse and cl_nrmse equally. no_aug gives 0.141/0.104. Light reynolds aug gives 0.200/0.056. What if I use a SMALLER velocity augmentation range, just enough to cover the test extrapolation without going crazy? The real test is only ~1.09x beyond train max. So for the final model (train max 75), I only need to cover up to ~82, maybe ~90 to be safe. That's a multiplier up to 90/75 = 1.2 at the TOP velocities, but for LOW velocity cases (31) I don't need to scale them to 90. Actually the augmentation scales each case's velocity by a random factor. A case at vel=31 scaled by 1.3 → 40, which is in-distribution. A case at vel=63 scaled by 1.3 → 82. So the factor mainly matters for high-velocity cases reaching the extrapolation zone. That's fine. Hmm, but the degradation in cd_nrmse is real. Let me look more carefully. Let me reconsider whether the physics correction exponent should be applied. Let me compare reyn (cd_exp=-0.21) vs pure invariance (cd_exp=0) once that result is in. Actually the key realization: maybe for C_D the no-aug model is just better because it learns the velocity trend directly from data, and my pseudo-test at thresh=63 (19% extrapolation) is more aggressive than reality. Let me test at thresh=70 (≈ real 9% extrapolation) where I expect no-aug to do even better on C_D, and aug to still help C_L. Let me also reconsider: maybe a better approach is MILD velocity aug (small jitter, like ±5-8%) that regularizes without large extrapolation, combined with the Reynolds correction. This would reduce C_L's spurious velocity dependence somewhat while not destroying C_D. Let me test vel_mult around 0.05-0.08. Let me wait for the last result then launch a thresh-70 comparison and a mild-aug sweep.
Stronger velocity augmentation keeps helping C_L but keeps hurting `cd_nrmse`, even with the correct Reynolds exponent. Notably `cd_nmae` (typical error) stays good while `cd_nrmse` (RMS) worsens , so a few C_D outliers are inflating the RMS. My thresh=63 holdout is also a very aggressive 19% extrapolation; the real public test is only ~9% beyond training. Let me investigate the C_D outliers and test at a more realistic threshold.
bash
cd /app && sleep 30 && cat results.txt 2>/dev/null | tail -1
# investigate C_D error structure: no_aug vs reyn, where do errors concentrate?
python3 -c "
import torch, numpy as np
from run_exp import pseudo_split
from exp import load_all, standardize_stats, train_model, predict
ptr,ttr,_,_=load_all()
xtr,ytr,xte,yte=pseudo_split(ptr,ttr,63.0)
fmean,fstd,tmean,tstd=standardize_stats(xtr,ytr)
velte=xte[:,0,2].numpy(); aoate=xte[:,0,3].numpy()
def run1(cfg,seed=0):
    res,_=train_model(xtr,ytr,cfg,fmean,fstd,tmean,tstd,seed=seed)
    return predict(res['final'],xte,fmean,fstd,tmean,tstd).numpy()
BASE=dict(epochs=80,lr=1e-3,wd=1e-4,sched='cosine',loss='mse')
na=run1(BASE)
ra=run1(dict(BASE,vel_mult=0.10,vel_mult_hi=0.30,cd_exp=-0.21))
cd_true=yte[:,0].numpy()
for nm,pr in [('no_aug',na),('reyn',ra)]:
    err=np.abs(pr[:,0]-cd_true)
    order=np.argsort(-err)[:5]
    print(nm,'top5 CD abs err:', np.round(err[order],4), 'at cd_true',np.round(cd_true[order],4),'vel',np.round(velte[order],1),'aoa',np.round(aoate[order],3))
" 2>&1 | tail -8
output
reyn_m20_60        mean=0.1808 cd=0.3131 cl=0.0485 worst=0.3131 cd_nmae=0.0366 (112s)
no_aug top5 CD abs err: [0.0031 0.0027 0.0023 0.0022 0.002 ] at cd_true [0.0269 0.0166 0.0199 0.0142 0.0232] vel [70.5 74.9 67.  74.6 65.9] aoa [0.233 0.208 0.232 0.188 0.242]
reyn top5 CD abs err: [0.0079 0.0034 0.0033 0.0027 0.0025] at cd_true [0.0084 0.0232 0.0199 0.0235 0.0237] vel [65.6 65.9 67.  72.6 74.3] aoa [-0.079  0.242  0.232  0.244  0.251]
The reyn model's worst C_D error is 0.0079 at cd_true=0.0084, vel=65.6, aoa=-0.079 (negative aoa, low drag case). So it badly over-predicts a LOW-drag case (predicting ~0.0163 when truth is 0.0084). That's almost a 2x error on a low-drag, negative-aoa case. Interesting , the velocity augmentation hurts the low-drag (negative/low aoa) cases. Possibly because augmenting velocity with the -0.21 exponent and the interplay with aoa creates confusion at the extremes. Or the negative-aoa low-drag regime is rare and the aug perturbs it. The no_aug top errors are at high aoa (0.23-0.25), high drag cases , it slightly under-predicts the highest drags. Those are more "honest" errors near the high-drag boundary. So the two models fail differently. The reyn model has a big outlier at a low-drag case. This single outlier (0.0079) heavily inflates reyn's RMS. With ~173 test points, one error of 0.0079 vs typical 0.002... RMS contribution. Let me step back and think strategically about the REAL objective. The real test: velocity 75-82 (public) and the hidden scored set is "higher-speed, higher-Reynolds end," sampled beyond training velocities. Let me reconsider what wins. The mean_nrmse combines cd and cl equally. Currently: - no_aug: cd 0.141, cl 0.104 → mean 0.123 - reyn light: cd 0.200, cl 0.056 → mean 0.128 These are close. But my thresh=63 is a 19% extrapolation, more aggressive than the real ~9%. At a milder extrapolation (thresh 70), the no_aug C_L spurious-velocity problem would be smaller, and no_aug might dominate. But the problem explicitly warns about extrapolation and the hidden set might be more aggressive than public_test. Let me think about whether I can get the best of both: - Use velocity augmentation to fix C_L (big win on C_L). - Prevent the C_D degradation. Idea: Apply velocity augmentation but make the C_D handling robust. The degradation came from a low-drag outlier. Perhaps using Huber loss (robust) would reduce the RMS impact of such outliers during training AND the model would be less swayed. But the metric is RMS, so I want to minimize RMS on test, and Huber during training trades off. Another idea: asymmetric/smaller velocity range that still covers test. Let me try vel_mult with only upward scaling and smaller magnitude: e.g., factor in [0.95, 1.25] (vel_mult=0.05, vel_mult_hi=0.25). This exposes higher velocities (for extrapolation) with minimal downward perturbation. And maybe the C_L benefit is retained while C_D degradation is reduced. Actually, the fundamental question: why does velocity aug help C_L so much? Because without aug, the model uses velocity as a (spurious) predictor for C_L, and at extrapolation that hurts. With aug, C_L becomes velocity-invariant → robust. The magnitude of velocity perturbation needed to "teach invariance" need not be huge; even moderate jitter decorrelates velocity from C_L in training. Let me reconsider with a cleaner approach: Instead of (or in addition to) random scaling, I could make the velocity channel less dominant by a different normalization so its extrapolation is gentler. But aug is more direct. Let me design a targeted sweep at thresh=70 (realistic) AND thresh=63 (aggressive), testing: 1. no_aug 2. mild up-aug: vel_mult=0.05, hi=0.25, cd_exp=-0.21 3. reyn_m10_30 (already have at 63) 4. Huber + reyn light And importantly, I should test the FINAL evaluation scenario where I train on ALL data (train max 75) and need to extrapolate to 75-82. I can't test that directly (no labels), but I can sanity check predictions and ranges. Let me be efficient. Let me run thresh=70 for no_aug and reyn_m10_30 and a mild version, plus a couple at thresh 63. Run in background. Actually, let me reconsider the metric normalization issue which could change my conclusions. The pseudo-test at thresh=63 normalizes by the std of yte over [63,75]. At thresh=70, the test set [70,75] is smaller (70 cases) and has different std. The std normalization changes. For comparing strateg …[truncated]
The reyn model's worst C_D error is a low-drag, negative-aoa case it over-predicts , velocity aug disturbs the low-drag regime, inflating RMS. The two approaches fail differently. Since the real test is a milder extrapolation than my thresh=63 holdout, let me evaluate at multiple thresholds and test a gentler, mostly-upward velocity augmentation. Let me make the runner threshold-configurable.
bash
cd /app && cat > runbg2.py << 'EOF'
import sys, time
from run_exp import run
BASE=dict(epochs=80,lr=1e-3,wd=1e-4,sched='cosine',loss='mse')
def cfg(**kw):
    c=dict(BASE); c.update(kw); return c
ALL={
 'no_aug':        cfg(),
 'reyn_m05_25':   cfg(vel_mult=0.05, vel_mult_hi=0.25, cd_exp=-0.21),
 'reyn_m05_20':   cfg(vel_mult=0.05, vel_mult_hi=0.20, cd_exp=-0.21),
 'reyn_m10_30':   cfg(vel_mult=0.10, vel_mult_hi=0.30, cd_exp=-0.21),
 'reyn_m08_25_hub':cfg(vel_mult=0.08, vel_mult_hi=0.25, cd_exp=-0.21, loss='huber', huber_beta=0.5),
}
thresh=float(sys.argv[1]); keys=sys.argv[2:]
out=open('results.txt','a')
for k in keys:
    t=time.time()
    m=run(ALL[k], thresh=thresh, seeds=(0,1,2), verbose=False)
    line=f"T{thresh:.0f} {k:16s} mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f} worst={m['worst_nrmse_std']:.4f} cd_nmae={m['cd_nmae']:.4f} meanRNG={m['mean_nrmse_rng']:.4f} ({time.time()-t:.0f}s)"
    print(line); out.write(line+'\n'); out.flush()
out.close()
EOF
rm -f results.txt
export OMP_NUM_THREADS=16
nohup python3 runbg2.py 70 no_aug reyn_m05_25 reyn_m10_30 > sweepT70.log 2>&1 &
echo "started T70 pid $!"
output
started T70 pid 27254
bash
cd /app && sleep 290 && cat results.txt 2>/dev/null
output
T70 no_aug           mean=0.1064 cd=0.1326 cl=0.0802 worst=0.1326 cd_nmae=0.0235 meanRNG=0.0257 (137s)
T70 reyn_m05_25      mean=0.0827 cd=0.1192 cl=0.0462 worst=0.1192 cd_nmae=0.0248 meanRNG=0.0194 (137s)
Now at thresh=70 (a milder ~7% extrapolation, closer to the real public test): - no_aug: mean=0.1064, cd=0.1326, cl=0.0802 - reyn_m05_25: mean=0.0827, cd=0.1192, cl=0.0462 ← BETTER on BOTH! So at the realistic extrapolation distance, the gentle mostly-upward velocity augmentation (factor [0.95, 1.25]) with Reynolds correction improves BOTH C_D (0.133→0.119) and C_L (0.080→0.046)! mean drops from 0.106 to 0.083. This is a solid win. This makes sense: at milder extrapolation, the gentle aug exposes the model to the near-test velocity range and teaches the right trends, without the aggressive over-extrapolation that hurt C_D at thresh=63 with strong aug. Let me wait for reyn_m10_30 at T70. Then I should confirm the gentle aug is robust. Let me continue. The key insight: the degree of velocity augmentation should be matched to the extrapolation distance. Since real test is ~9% above train max (public 82 vs 75), and hidden might be a bit more, a gentle upward aug (up to +25%) covering that range is ideal. Let me wait for the third result then run more around the gentle-aug optimum and also test at thresh=67 to triangulate.
At the realistic extrapolation distance (thresh=70, ~7% beyond train), the gentle mostly-upward augmentation (factor [0.95, 1.25]) with Reynolds correction **improves both targets**: mean 0.106→0.083, C_D 0.133→0.119, C_L 0.080→0.046. The augmentation strength should match the extrapolation distance. Let me get the third result and refine around this optimum.
bash
cd /app && sleep 130 && cat results.txt 2>/dev/null | tail -2
# launch refinement around gentle aug at T70 and also T67
export OMP_NUM_THREADS=16
nohup python3 runbg2.py 70 reyn_m05_20 reyn_m08_25_hub > sweepT70b.log 2>&1 &
echo "started T70b pid $!"
output
T70 reyn_m05_25      mean=0.0827 cd=0.1192 cl=0.0462 worst=0.1192 cd_nmae=0.0248 meanRNG=0.0194 (137s)
T70 reyn_m10_30      mean=0.0861 cd=0.1284 cl=0.0438 worst=0.1284 cd_nmae=0.0268 meanRNG=0.0201 (132s)
started T70b pid 27302
At T70: - no_aug: mean=0.1064, cd=0.1326, cl=0.0802 - reyn_m05_25: mean=0.0827, cd=0.1192, cl=0.0462 ← best so far - reyn_m10_30: mean=0.0861, cd=0.1284, cl=0.0438 So reyn_m05_25 (factor [0.95,1.25]) is the best. reyn_m10_30 has slightly better cl but worse cd. The gentle one wins on mean. I'm now running reyn_m05_20 and reyn_m08_25_hub. Let me wait. Meanwhile, let me think about additional improvements: 1. EMA/SWA for better generalization. 2. Ensemble across seeds via weight averaging (model soup) , but single checkpoint. Actually I realize I CAN only submit one state_dict. But SWA within a run gives one state_dict. And EMA gives one. Those are my tools for the "ensemble-like" benefit. Let me test EMA and SWA. 3. Geometry jitter for regularization. 4. Larger epochs. But also, I should think about whether to train the FINAL model on train+val combined. Val has 80 more cases in the same velocity range. More data → better. For the final, I'll combine train+val (710 cases), compute standardization on the combined set, and train with the chosen config. The velocity range is still 31-75, and aug extends it upward. Let me also reconsider the cd_exp. At T70, does the exponent matter? Let me test cd_exp=0 (pure invariance) vs -0.21 vs maybe -0.3 at the gentle setting. Earlier at T63 reyn_m10_30_e0 (cd_exp=0) , let me check that result; it was in the first sweep but may not have printed. Let me check sweep1.log. Actually, the first background job (runbg.py) included reyn_m10_30_e0 at thresh=63. Let me check if it finished.
Let me check the earlier cd_exp=0 result and confirm the gentle-aug refinements, then plan EMA/SWA tests.
bash
cd /app && echo "--- sweep1.log (T63, includes cd_exp=0) ---" && cat sweep1.log 2>/dev/null | grep -E "no_aug|reyn" 
output
--- sweep1.log (T63, includes cd_exp=0) ---
no_aug             mean=0.1227 cd=0.1414 cl=0.1040 worst=0.1414 cd_nmae=0.0342 (98s)
reyn_m10_30        mean=0.1281 cd=0.2002 cl=0.0559 worst=0.2002 cd_nmae=0.0306 (112s)
reyn_m15_40        mean=0.1572 cd=0.2631 cl=0.0514 worst=0.2631 cd_nmae=0.0345 (111s)
reyn_m20_60        mean=0.1808 cd=0.3131 cl=0.0485 worst=0.3131 cd_nmae=0.0366 (112s)
reyn_m10_30_e0     mean=0.1599 cd=0.2634 cl=0.0563 worst=0.2634 cd_nmae=0.0503 (154s)
At T63: reyn_m10_30 (cd_exp=-0.21) gives cd=0.2002, while reyn_m10_30_e0 (cd_exp=0, pure invariance) gives cd=0.2634. So the Reynolds correction (cd_exp=-0.21) clearly helps C_D vs pure invariance (0.200 < 0.263), and also helps cd_nmae (0.0306 vs 0.0503). This confirms the physics-based correction is beneficial. Good , keep cd_exp=-0.21. Now let me wait for the T70b results (reyn_m05_20, reyn_m08_25_hub). Let me think about the bigger picture and time budget. I've used a good chunk. Let me plan: 1. Confirm gentle aug config (~reyn_m05_25) is robust, pick the best aug strength. 2. Add EMA or SWA , test quickly. 3. Possibly geometry jitter. 4. Train final on train+val with chosen config, maybe average multiple seeds via SWA-like, save checkpoint. 5. Validate checkpoint loads and produces sane predictions on public_test. Let me wait for T70b.
The physics correction is confirmed better than pure invariance (at T63, cd_exp=−0.21 gives C_D 0.200 vs 0.263 for cd_exp=0). Let me wait for the gentle-aug refinements.
bash
cd /app && sleep 280 && grep "T70" results.txt 2>/dev/null
output
T70 no_aug           mean=0.1064 cd=0.1326 cl=0.0802 worst=0.1326 cd_nmae=0.0235 meanRNG=0.0257 (137s)
T70 reyn_m05_25      mean=0.0827 cd=0.1192 cl=0.0462 worst=0.1192 cd_nmae=0.0248 meanRNG=0.0194 (137s)
T70 reyn_m10_30      mean=0.0861 cd=0.1284 cl=0.0438 worst=0.1284 cd_nmae=0.0268 meanRNG=0.0201 (132s)
T70 reyn_m05_20      mean=0.0825 cd=0.1156 cl=0.0494 worst=0.1156 cd_nmae=0.0253 meanRNG=0.0195 (132s)
T70 reyn_m08_25_hub  mean=0.0709 cd=0.1038 cl=0.0380 worst=0.1038 cd_nmae=0.0186 meanRNG=0.0166 (137s)
reyn_m08_25_hub is the best by a good margin: - mean=0.0709, cd=0.1038, cl=0.0380, cd_nmae=0.0186, meanRNG=0.0166 This config: vel_mult=0.08, vel_mult_hi=0.25 (factor [0.92, 1.25]), cd_exp=-0.21, Huber loss with beta=0.5. The Huber loss (beta=0.5 in standardized space) helped a LOT , it's robust to the C_D outliers I identified. mean dropped from 0.083 to 0.071, cd from 0.119 to 0.104, cl from 0.046 to 0.038, and cd_nmae from 0.025 to 0.019. So Huber loss is a big win. This makes sense: the C_D RMS was being inflated by a few outliers, and Huber reduces their influence during training, which apparently generalizes better. Wait, but Huber reduces the penalty on large errors during TRAINING. The test metric is RMS (sensitive to outliers). Yet Huber IMPROVED the test RMS. This means the large training errors were from label noise / hard cases, and down-weighting them during training leads to a better-generalizing model overall, reducing test outliers. Good. Let me now refine around this: test different huber_beta values and confirm robustness. Also test adding EMA/SWA and geometry jitter on top. Let me be strategic with remaining time. Let me run a focused sweep at T70: - reyn_m08_25_hub with huber_beta in {0.3, 0.5, 1.0} - reyn_m08_25_hub + EMA - reyn_m08_25_hub + geom jitter - reyn_m08_25_hub + SWA Let me also verify at T67 (a bit more aggressive) that the config still wins, to ensure robustness to the unknown hidden-set distance. Let me set up a new runner with these configs. Since each run is ~135s and I can do ~2 per 300s poll, let me batch carefully and run in background. Let me update runbg to include the huber/ema/swa/geom variants.
**`reyn_m08_25_hub` is a clear winner**: mean 0.071 (vs 0.106 no-aug). The Huber loss (β=0.5) gave a big boost by taming the C_D outliers that were inflating RMS. Config: velocity factor [0.92, 1.25], cd_exp=−0.21, Huber. Let me now refine β and stack EMA/SWA/geometry-jitter on top, and verify robustness at a more aggressive threshold.
bash
cd /app && cat > runbg3.py << 'EOF'
import sys, time
from run_exp import run
BASE=dict(epochs=80,lr=1e-3,wd=1e-4,sched='cosine')
def cfg(**kw):
    c=dict(BASE); c.update(kw); return c
H=dict(vel_mult=0.08, vel_mult_hi=0.25, cd_exp=-0.21, loss='huber', huber_beta=0.5)
ALL={
 'hub50':     cfg(**H),
 'hub30':     cfg(**{**H,'huber_beta':0.3}),
 'hub100':    cfg(**{**H,'huber_beta':1.0}),
 'hub50_ema': cfg(**{**H,'ema':0.995}),
 'hub50_swa': cfg(**{**H,'swa_start_frac':0.6}),
 'hub50_g002':cfg(**{**H,'geom_jitter':0.002}),
 'hub50_e120':cfg(**{**H,'epochs':120}),
}
thresh=float(sys.argv[1]); which=sys.argv[2]; keys=sys.argv[3:]
out=open('results.txt','a')
for k in keys:
    t=time.time()
    m=run(ALL[k], thresh=thresh, seeds=(0,1,2), which=which)
    line=f"T{thresh:.0f} {which:5s} {k:12s} mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f} cd_nmae={m['cd_nmae']:.4f} ({time.time()-t:.0f}s)"
    out.write(line+'\n'); out.flush()
out.close()
EOF
export OMP_NUM_THREADS=16
nohup python3 runbg3.py 70 final hub30 hub100 > s3a.log 2>&1 &
echo "started pid $!"
output
started pid 27356
bash
cd /app && sleep 290 && grep -E "hub30|hub100" results.txt 2>/dev/null
output
T70 final hub30        mean=0.0690 cd=0.1000 cl=0.0380 cd_nmae=0.0183 (153s)
T70 final hub100       mean=0.0767 cd=0.1117 cl=0.0418 cd_nmae=0.0197 (128s)
huber_beta=0.3 is slightly better than 0.5 (mean 0.069 vs 0.071), and 1.0 is worse (0.077). So smaller beta (more robust, closer to L1) helps. Let me note: - hub30: mean=0.0690, cd=0.1000, cl=0.0380 - hub50: mean=0.0709, cd=0.1038, cl=0.0380 - hub100: mean=0.0767 Let me test even smaller beta (0.2) and the EMA/SWA/geom/epochs variants. Let me run the EMA and SWA next (with beta 0.5 base, but I could switch base to 0.3). Let me run ema and swa with the hub50 base first since those are already defined, plus geom and e120. Actually let me just run them. Let me launch the next batch: hub50_ema, hub50_swa.
β=0.3 edges out β=0.5 (mean 0.069). Let me test the EMA and SWA weight-averaging variants, which produce a single checkpoint compatible with the contract.
bash
cd /app && export OMP_NUM_THREADS=16
nohup python3 runbg3.py 70 ema hub50_ema > s3b.log 2>&1 &
nohup python3 runbg3.py 70 swa hub50_swa > s3c.log 2>&1 &
echo "started ema+swa"
output
started ema+swa
Wait, running two in parallel will compete for the 16 threads. Each run spawns torch which uses all threads. Running two at once will slow both. But it's fine; total wall time similar. Let me wait. Actually, let me reconsider , running 2 parallel jobs each trying to use 16 threads on 16 cores → 2x oversubscription → each ~2x slower, no net gain, and possibly contention. Let me instead limit threads per job. But they're already launched. Let me just wait longer. Let me set a reasonable sleep. Actually let me kill and relaunch with thread limits to be clean. Hmm, but they're running. Let me just let them run and poll; even if slower, results will come. Let me wait. While waiting, let me think about the final training plan and write the final training script so I'm ready. Final plan: - Train on train+val combined (710 cases), velocity 31-75. - Standardization: compute feat_mean/std and targ_mean/std on the combined training data (physical). These go in the checkpoint. - Config: gentle Reynolds velocity aug (vel_mult=0.08, hi=0.25, cd_exp=-0.21), Huber loss beta~0.3-0.5, cosine schedule, 80-120 epochs. - Weight averaging: EMA or SWA (whichever wins) to get a robust single checkpoint. Recompute BN stats after averaging. - Possibly: since the real test goes up to 82 (9% above 75) and maybe higher in hidden set, I might widen the upward aug slightly for the FINAL model (train max is 75, so to cover 82-90 I need factor up to ~1.2; factor [0.92,1.25] covers 75*1.25=93.75, plenty). Good, keep. Wait , one concern: in my pseudo-experiments, pseudo-train max is 70 (for T70) and aug factor up to 1.25 reaches 87.5, covering the test [70,75] well. For the FINAL model, train max is 75, aug to 93.75, covering test [75,82+]. Consistent. Good. Let me also consider: should I widen the upward augmentation for the final model to be safe for a potentially higher hidden set? The problem says "higher-speed, higher-Reynolds end" and public_test is 75-82. Hidden scored set might be similar or a bit higher. Factor 1.25 from 75 = 93.75. Should be plenty. But if I want robustness, maybe 1.30. But larger aug hurt at T63. At T70 the sweet spot was ~0.25 upper. I'll keep ~0.25-0.30. Let me maybe test 0.30 upper for the final since the real train max is higher. Now, about the final model using train+val: My pseudo-experiments use train only (split by velocity). The final uses train+val. The configs should transfer. Let me also decide EMA vs SWA vs plain final by the experiment. Let me wait for those results. Let me also prepare: I want to ALSO evaluate the chosen config's STABILITY by checking the standard val set (in-distribution, 31-75) to make sure I'm not regressing badly there , though it's not the target, a sanity check. Let me wait for ema/swa results. They're running in parallel so slower (~250-300s each). Let me sleep.
While those run, let me reconsider thread usage , two parallel jobs oversubscribe the cores. Let me wait for them and meanwhile verify that nothing is wrong by checking progress.
bash
cd /app && sleep 295 && grep -E "hub50_ema|hub50_swa" results.txt 2>/dev/null; echo "(still running if empty)"; ps aux | grep -c "[r]unbg3"
output
T70 swa   hub50_swa    mean=0.0870 cd=0.1225 cl=0.0515 cd_nmae=0.0281 (265s)
T70 ema   hub50_ema    mean=0.0835 cd=0.1168 cl=0.0501 cd_nmae=0.0278 (270s)
(still running if empty)
0
Hmm, surprising: - hub50 (final weights): mean=0.0709 - hub50_ema (EMA weights): mean=0.0835 , WORSE - hub50_swa (SWA weights): mean=0.0870 , WORSE So EMA and SWA are WORSE than just using the final weights here. That's unexpected but can happen: with a cosine schedule decaying to near-zero LR, the final weights are already well-converged and "averaged" implicitly by the low LR. EMA with decay 0.995 lags behind and includes earlier higher-LR weights. SWA from 60% includes weights from when LR was still moderate. Both pull toward less-converged states. Also possible: BN recomputation interaction. But regardless, empirically final > ema > swa. So I'll use the final weights (with cosine decay to low LR). Good , simpler. But wait, let me reconsider. The benefit of EMA/SWA is usually variance reduction across the noisy trajectory. Here with cosine to lr_min=1e-5 and 80 epochs, the end is very stable. EMA decay 0.995 over ~20 steps/epoch → effective window ~200 steps = 10 epochs, which includes epoch ~70-80 where LR is low. Should be fine-ish but apparently the non-averaged final is better. I'll drop EMA/SWA. Instead, to reduce variance and get a robust single model, I could train longer and/or rely on the cosine convergence. The 3-seed averaging in my experiments is for evaluation stability; the final single model can't ensemble. But I could do a "model soup" from the same init... let me not overcomplicate. Let me just pick the best single-run config and train it. Actually, variance across seeds matters for the final single model. Let me check the seed variance of the best config to understand how much a single seed might deviate. Let me also decide whether to pick the best of several seeds using the standard val set (in-distribution) , but that doesn't test extrapolation. Risky. Alternative for robustness without ensembling: Since I can only submit one state_dict, but the grader just runs one forward pass, I could consider that the 3-seed-averaged prediction is better than any single seed. To approximate that benefit in a single model, weight-averaging (soup) of models trained from the SAME init with different data orders could work. Let me quickly test: train 3 models from the same seed-init but different data shuffling (or different aug RNG), average their weights, recompute BN, and see if it beats a single model. This is a legitimate single-checkpoint technique. Actually, models trained from the same initialization but different SGD noise can often be averaged successfully (they stay in the same loss basin), especially for small models and short training. Let me test a "soup" at T70. Let me implement soup: train K models with same torch.manual_seed for init but advance RNG differently for shuffling/aug, then average the float params, recompute BN. Hmm, but train_model seeds everything with `seed`, controlling both init and shuffling. To get same init but different noise, I'd seed init, then re-seed for the loop. Let me add a soup mode. Actually, simpler and proven: just run the final config and accept single-seed variance. But let me quantify the variance first , run the best config with which='final' for seeds individually. Actually my run() averages predictions across seeds. Let me measure per-seed spread quickly by evaluating each seed. That costs another ~3 runs. Given time, let me be decisive: 1. Use config: reyn gentle aug (0.08, 0.25), cd_exp -0.21, huber_beta 0.3, cosine 80-120 ep, final weights. 2. For robustness, test the "model soup" (same-init weight averaging) quickly at T70 , if it helps, use it; else single model. Let me also re-examine: the best single result hub30 mean=0.069 used 3-seed PREDICTION averaging. A single seed will be a bit worse/noisier. Soup could recover some of that. Let me implement and test soup efficiently. Let me add to exp.py a function to average states and a soup training that reuses one training but saves snapshots? No , soup needs independent runs. Let me reconsider time …[truncated]
Interesting , EMA (0.084) and SWA (0.087) are both **worse** than the plain final weights (0.071). With cosine decay to a low LR, the final weights are already well-converged, and averaging pulls in earlier, higher-LR states. So I'll use final weights. Since I can only submit one checkpoint (no prediction ensembling), let me test a **"model soup"** , averaging weights of models trained from the *same initialization* with different SGD/augmentation noise, which stays in one basin and is a legitimate single-checkpoint variance reducer. Let me add that capability.
str_replace_based_edit_tool
command: str_replace
path: /app/exp.py
old_str: def train_model(xtr_phys, ytr, cfg, fmean, fstd, tmean, tstd, seed=0, verbose=False):
    torch.manual_seed(seed); np.random.seed(seed)
    device = 'cpu'
    model = build_model(CFG).to(device)
new_str: def train_model(xtr_phys, ytr, cfg, fmean, fstd, tmean, tstd, seed=0, verbose=False,
                init_seed=None):
    device = 'cpu'
    # Optionally fix the initialization across runs (for weight-averaging soups)
    torch.manual_seed(init_seed if init_seed is not None else seed)
    model = build_model(CFG).to(device)
    torch.manual_seed(seed); np.random.seed(seed)
output
The file /app/exp.py has been edited successfully.
bash
cd /app && cat > soup_test.py << 'EOF'
import time, torch
import numpy as np
from run_exp import pseudo_split
from exp import load_all, standardize_stats, train_model, recompute_bn, predict, nrmse_metrics

ptr,ttr,pva,tva=load_all()
xtr,ytr,xte,yte=pseudo_split(ptr,ttr,70.0)
fmean,fstd,tmean,tstd=standardize_stats(xtr,ytr)
BASE=dict(epochs=80,lr=1e-3,wd=1e-4,sched='cosine',vel_mult=0.08,vel_mult_hi=0.25,cd_exp=-0.21,loss='huber',huber_beta=0.3)

def avg_states(states):
    out={}
    for k in states[0]:
        if states[0][k].dtype.is_floating_point:
            out[k]=sum(s[k].float() for s in states)/len(states)
        else:
            out[k]=states[0][k].clone()
    return out

# Per-seed (independent init) performance + prediction-ensemble
states_indep=[]; preds_indep=[]
for sd in [0,1,2]:
    res,_=train_model(xtr,ytr,BASE,fmean,fstd,tmean,tstd,seed=sd)
    states_indep.append(res['final'])
    preds_indep.append(predict(res['final'],xte,fmean,fstd,tmean,tstd))
for i,sd in enumerate([0,1,2]):
    m=nrmse_metrics(preds_indep[i],yte)
    print(f"seed{sd} single: mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f}")
m=nrmse_metrics(torch.stack(preds_indep).mean(0),yte)
print(f"PRED-ENSEMBLE(3 indep): mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f}")

# Soup: same init, different noise seeds
states_soup=[]
for sd in [10,11,12,13]:
    res,_=train_model(xtr,ytr,BASE,fmean,fstd,tmean,tstd,seed=sd,init_seed=777)
    states_soup.append(res['final'])
soup=avg_states(states_soup)
soup=recompute_bn(soup,xtr,fmean,fstd,BASE)
m=nrmse_metrics(predict(soup,xte,fmean,fstd,tmean,tstd),yte)
print(f"SOUP(4 same-init): mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f}")
EOF
export OMP_NUM_THREADS=16
nohup python3 soup_test.py > soup.log 2>&1 &
echo "started soup pid $!"
output
started soup pid 27492
bash
cd /app && sleep 295 && cat soup.log 2>/dev/null; echo "(empty=still running)"
output
(empty=still running)
It's still running (7 training runs total: 3 indep + 4 soup = 7 × ~50s single-thread... wait, with averaging over seeds these are single runs each ~50s? No, each train_model is one model. 7 models × ~45s each = ~315s). Let me wait more.
bash
cd /app && sleep 120 && cat soup.log 2>/dev/null; echo "(empty=still running)"
output
seed0 single: mean=0.0673 cd=0.0893 cl=0.0452
seed1 single: mean=0.0623 cd=0.0865 cl=0.0382
seed2 single: mean=0.0753 cd=0.1041 cl=0.0464
PRED-ENSEMBLE(3 indep): mean=0.0647 cd=0.0890 cl=0.0404
SOUP(4 same-init): mean=0.0984 cd=0.1319 cl=0.0648
(empty=still running)
Results: - Single seeds: mean 0.067, 0.062, 0.075 , variance is moderate (0.062-0.075). - PRED-ENSEMBLE(3 indep): mean=0.0647 , better than average single, comparable to best single. - SOUP(4 same-init): mean=0.0984 , WORSE! Weight averaging (soup) hurt. So the soup doesn't work here (the models don't align well enough in weight space even from same init, likely due to BatchNorm and the nonlinearity , averaging degrades). Prediction ensembling works but I can't submit multiple models. So for the final single checkpoint, I should just train a single model with the best config and a good seed. The variance across seeds (0.062-0.075) means seed choice matters somewhat. How to pick a good seed without overfitting to the pseudo-test? I could select by the standard val set (in-distribution). But in-distribution val performance may not correlate with extrapolation. Alternatively, I pick based on the pseudo-extrapolation holdout , but that's using the held-out high-velocity cases for selection, which is legitimate model selection for extrapolation. However, if I select the seed using the SAME pseudo-test I'd report on, that's optimistic. But I don't report; I just need the real hidden test to be good. Selecting a seed that does well on the pseudo-extrapolation (train<70, test 70-75) is a reasonable proxy for doing well on the real extrapolation (train<75, test 75-82). But here's a subtlety: for the FINAL model I train on train+val (all velocities up to 75) and test on 75-82. For seed selection, I can't replicate that exactly. Better robustness idea: Since prediction-ensembling helps and I can't submit multiple models, what about training ONE model but reducing variance via a longer cosine schedule and more data (train+val)? More data → lower variance. Let me also consider: the difference between single seeds (0.062 to 0.075) is not huge. The expected single-seed ~0.067, ensemble 0.065. Not a big ensembling gain here anyway (the models are fairly consistent). So a single well-trained model is fine. Decision: Train the final model on train+val with the best config. To hedge seed variance, I'll train a few seeds and pick the one with the best pseudo-extrapolation score using a held-out high-velocity slice of the combined data (train+val with vel in some top range as validation), OR simply pick by the standard val set. Let me think about the cleanest selection. Actually, the cleanest and most principled: For the FINAL deliverable, I want maximum data AND good extrapolation. Let me do this: - Final training data: all of train+val (710 cases). - Config: the best one (gentle reyn aug, huber 0.3, cosine, maybe 100-120 epochs). - To select among seeds robustly, use a held-out extrapolation check: hold out the top-velocity slice (vel>=70) of train+val as a selection validation, train on the rest with the config, evaluate extrapolation, pick best seed. Then RETRAIN that seed on ALL data (including the held-out) for the final model. But retraining changes the model... The seed's relative quality may not transfer after adding data. This is getting complicated. Given the models are fairly consistent (0.062-0.075) and ensembling barely helps, let me just: 1. Train the final model on ALL train+val data with the best config, using a fixed seed. 2. Train maybe 2-3 seeds and, as a light selection, evaluate each on the standard val set (in-distribution sanity) AND on a held-out top-velocity slice to pick the most robust. Actually, since I train on ALL data including val, I can't use val for selection cleanly. Simplest robust choice: train on train+val, multiple seeds, and among them pick the seed whose predictions on the public_test set are most "central" / agree best with the ensemble mean (a form of ensemble-centroid selection). Actually, I can compute the ensemble mean prediction on public_test from several seeds, then pick the single seed closest to that mean → that seed is the most "representative" and likely has lower variance error. Th …[truncated]
Key findings: the **soup (weight averaging) fails** (0.098, worse), while prediction-ensembling barely helps (0.065 vs ~0.067 single) since seeds are fairly consistent (0.062–0.075). So a single well-trained model is the right call. Let me lock the config by testing β=0.2/0.3, more epochs, and a slightly wider upper bound (for safety if the hidden set exceeds 82).
bash
cd /app && cat > runbg4.py << 'EOF'
import sys, time
from run_exp import run
BASE=dict(epochs=80,lr=1e-3,wd=1e-4,sched='cosine',vel_mult=0.08,vel_mult_hi=0.25,cd_exp=-0.21,loss='huber',huber_beta=0.3)
def cfg(**kw):
    c=dict(BASE); c.update(kw); return c
ALL={
 'b30':       cfg(),
 'b20':       cfg(huber_beta=0.2),
 'b30_e120':  cfg(epochs=120),
 'b30_up30':  cfg(vel_mult_hi=0.30),
 'b30_e120_up30': cfg(epochs=120, vel_mult_hi=0.30),
}
thresh=float(sys.argv[1]); keys=sys.argv[2:]
out=open('results.txt','a')
for k in keys:
    t=time.time()
    m=run(ALL[k], thresh=thresh, seeds=(0,1,2))
    line=f"T{thresh:.0f} FIN {k:14s} mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f} cd_nmae={m['cd_nmae']:.4f} ({time.time()-t:.0f}s)"
    out.write(line+'\n'); out.flush()
out.close()
EOF
export OMP_NUM_THREADS=16
nohup python3 runbg4.py 70 b20 b30_e120 b30_up30 > s4a.log 2>&1 &
echo "started pid $!"
output
started pid 27546
bash
cd /app && sleep 295 && grep -E "FIN (b20|b30_e120|b30_up30)" results.txt 2>/dev/null
output
T70 FIN b20            mean=0.0656 cd=0.0901 cl=0.0411 cd_nmae=0.0167 (111s)
T70 FIN b30_e120       mean=0.0583 cd=0.0821 cl=0.0346 cd_nmae=0.0160 (154s)
- b30 (80ep): mean=0.0690 (from earlier) - b20 (80ep): mean=0.0656, cd=0.0901, cl=0.0411 , slightly better than b30 - b30_e120 (120ep): mean=0.0583, cd=0.0821, cl=0.0346 , BEST so far! More epochs help. So 120 epochs helps significantly (0.069 → 0.058). Let me wait for b30_up30. And I should test even more epochs (150-200) and b20 at 120 epochs. Let me wait for the third result, then launch more-epochs tests.
120 epochs gives a clear improvement (mean 0.069→0.058). Let me wait for the wider-bound result, then push epochs further and combine with β=0.2.
bash
cd /app && sleep 90 && grep -E "FIN b30_up30" results.txt 2>/dev/null
export OMP_NUM_THREADS=16
cat >> runbg4.py.ignore << 'EOF'
EOF
nohup python3 runbg4.py 70 b30_e120_up30 > s4b.log 2>&1 &
echo "launched e120_up30"
output
T70 FIN b30_up30       mean=0.0641 cd=0.0895 cl=0.0387 cd_nmae=0.0167 (105s)
launched e120_up30
- b30_up30 (upper 0.30, 80ep): mean=0.0641 , slightly better than b30 (0.069), comparable to b20. So far the best is b30_e120 at 0.0583. Let me test more epochs and combos. Let me add configs for 160/200 epochs, and b20_e120. Let me create a new runner for these. Let me also think about the total time budget , I've used substantial time. Let me be efficient: run b30_e160, b20_e120, b30_e200 in one job. But that's 3×~150-250s = ~600s. Let me do 2 at a time. Let me launch b20_e120 and b30_e160.
Best so far is **b30_e120 (mean 0.0583)** , more epochs clearly help. Let me push epochs further and combine with β=0.2.
bash
cd /app && cat > runbg5.py << 'EOF'
import sys, time
from run_exp import run
BASE=dict(lr=1e-3,wd=1e-4,sched='cosine',vel_mult=0.08,vel_mult_hi=0.25,cd_exp=-0.21,loss='huber',huber_beta=0.3)
def cfg(**kw):
    c=dict(BASE); c.update(kw); return c
ALL={
 'b30_e160':  cfg(epochs=160),
 'b30_e200':  cfg(epochs=200),
 'b20_e120':  cfg(epochs=120, huber_beta=0.2),
 'b30_e120_wd3':cfg(epochs=120, wd=3e-4),
}
thresh=float(sys.argv[1]); keys=sys.argv[2:]
out=open('results.txt','a')
for k in keys:
    t=time.time()
    m=run(ALL[k], thresh=thresh, seeds=(0,1,2))
    line=f"T{thresh:.0f} FIN {k:14s} mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f} cd_nmae={m['cd_nmae']:.4f} ({time.time()-t:.0f}s)"
    out.write(line+'\n'); out.flush()
out.close()
EOF
export OMP_NUM_THREADS=16
nohup python3 runbg5.py 70 b30_e160 b20_e120 > s5a.log 2>&1 &
echo "started pid $!"
output
started pid 27632
bash
cd /app && sleep 298 && grep -E "FIN (b30_e160|b20_e120|b30_e120_up30)" results.txt 2>/dev/null
output
<system>Tool ran without output or errors</system>
bash
cd /app && sleep 90 && grep -E "FIN (b30_e160|b20_e120|b30_e120_up30)" results.txt 2>/dev/null; echo "---tail---"; tail -3 results.txt
output
---tail---
T70 FIN b20            mean=0.0656 cd=0.0901 cl=0.0411 cd_nmae=0.0167 (111s)
T70 FIN b30_e120       mean=0.0583 cd=0.0821 cl=0.0346 cd_nmae=0.0160 (154s)
T70 FIN b30_up30       mean=0.0641 cd=0.0895 cl=0.0387 cd_nmae=0.0167 (105s)
The b30_e120_up30 job (runbg4.py 70 b30_e120_up30) and the runbg5 job (b30_e160, b20_e120) are both running , possibly in parallel, oversubscribing. That's why results are slow. Let me check processes and wait.
bash
cd /app && ps aux | grep "[r]unbg" | awk '{print $2, $11, $12, $13, $14}'; echo "---"; sleep 150 && grep -E "FIN (b30_e160|b20_e120|b30_e120_up30)" results.txt 2>/dev/null
output
27594 python3 runbg4.py 70 b30_e120_up30
27632 python3 runbg5.py 70 b30_e160
---
T70 FIN b30_e120_up30  mean=0.0577 cd=0.0822 cl=0.0331 cd_nmae=0.0160 (426s)
T70 FIN b30_e160       mean=0.0582 cd=0.0842 cl=0.0322 cd_nmae=0.0160 (490s)
Two jobs ran in parallel (hence the long times ~426s, 490s), but results came: - b30_e120_up30 (120ep, upper 0.30): mean=0.0577, cd=0.0822, cl=0.0331 , best! - b30_e160 (160ep): mean=0.0582 , basically same as e120 (0.0583). So beyond 120 epochs, no improvement. So 120 epochs is the sweet spot. And upper bound 0.30 is marginally better than 0.25 (0.0577 vs 0.0583), and gives extra safety margin for higher velocities. Good. Let me wait for b20_e120 (still running in runbg5). Then I'll lock the config: - epochs=120, lr=1e-3, cosine, wd=1e-4 - vel_mult=0.08, vel_mult_hi=0.30, cd_exp=-0.21 - huber_beta=0.3 Let me confirm b20_e120 and also I want to double-check robustness at a more aggressive threshold (T67) for the chosen config, to make sure it's not overfit to T70. Let me wait for b20_e120.
120 epochs is the sweet spot (160 gives no further gain), and the wider upper bound (0.30) is marginally better with added safety margin: **b30_e120_up30 → mean 0.0577**. Let me get the last comparison and then verify the chosen config at a more aggressive threshold to ensure it's not overfit to T70.
bash
cd /app && sleep 60 && grep -E "FIN b20_e120" results.txt 2>/dev/null; echo "launching robustness checks at T67 and T63"
cat > runbg6.py << 'EOF'
import sys, time
from run_exp import run
CHOSEN=dict(epochs=120,lr=1e-3,wd=1e-4,sched='cosine',vel_mult=0.08,vel_mult_hi=0.30,cd_exp=-0.21,loss='huber',huber_beta=0.3)
NOAUG=dict(epochs=120,lr=1e-3,wd=1e-4,sched='cosine',loss='mse')
ALL={'chosen':CHOSEN,'noaug120':NOAUG}
thresh=float(sys.argv[1]); keys=sys.argv[2:]
out=open('results.txt','a')
for k in keys:
    t=time.time()
    m=run(ALL[k], thresh=thresh, seeds=(0,1,2))
    line=f"T{thresh:.0f} CHK {k:10s} mean={m['mean_nrmse_std']:.4f} cd={m['cd_nrmse_std']:.4f} cl={m['cl_nrmse_std']:.4f} cd_nmae={m['cd_nmae']:.4f} ({time.time()-t:.0f}s)"
    out.write(line+'\n'); out.flush()
out.close()
EOF
export OMP_NUM_THREADS=16
nohup python3 runbg6.py 63 chosen noaug120 > s6a.log 2>&1 &
echo "started T63 check pid $!"
output
launching robustness checks at T67 and T63
started T63 check pid 27700
bash
cd /app && sleep 280 && grep -E "FIN b20_e120|T63 CHK" results.txt 2>/dev/null
output
T70 FIN b20_e120       mean=0.0594 cd=0.0828 cl=0.0359 cd_nmae=0.0155 (276s)
T63 CHK chosen     mean=0.0852 cd=0.1312 cl=0.0391 cd_nmae=0.0218 (221s)
- b20_e120: mean=0.0594 , basically same as b30_e120 (0.0583). β=0.3 slightly better. Keep β=0.3. - T63 CHK chosen: mean=0.0852, cd=0.1312, cl=0.0391. Let me wait for T63 noaug120 to compare at the aggressive threshold. At T63 (19% extrapolation), the chosen config gets mean=0.0852. Let me compare to no-aug at 120 epochs. Earlier no-aug at 80ep T63 was 0.1227. With 120 epochs no-aug might be a bit different. Let me see. Let me wait.
bash
cd /app && sleep 200 && grep -E "T63 CHK" results.txt 2>/dev/null
output
T63 CHK chosen     mean=0.0852 cd=0.1312 cl=0.0391 cd_nmae=0.0218 (221s)
T63 CHK noaug120   mean=0.1123 cd=0.1133 cl=0.1114 cd_nmae=0.0268 (113s)
At T63 (aggressive 19% extrapolation): - chosen: mean=0.0852, cd=0.1312, cl=0.0391 - noaug120: mean=0.1123, cd=0.1133, cl=0.1114 So at aggressive extrapolation, chosen is much better overall (0.085 vs 0.112), driven by huge C_L gain (0.039 vs 0.111). The no-aug C_D is slightly better (0.113 vs 0.131), but C_L is catastrophic for no-aug (0.111). So chosen wins decisively at aggressive extrapolation too. The chosen config is robust across both T70 (0.0577) and T63 (0.0852), and dominates no-aug at both. Summary of the chosen config: - epochs=120, lr=1e-3, cosine to lr_min=1e-5, wd=1e-4, bs=32 - velocity aug: multiply by factor ~U(0.92, 1.30) per case - C_D target correction: multiply by factor^(-0.21) (Reynolds) - C_L unchanged - Huber loss (beta=0.3) in standardized target space - final weights (no EMA/SWA) Now I'm confident. Let me finalize. The chosen config's C_D at T63 (0.131) is a bit worse than no-aug (0.113). Could I get C_D better while keeping C_L good? The tension remains but the mean strongly favors chosen. I could consider a slight per-target weighting to push C_D a bit. But the gains are marginal and I risk overfitting the holdout. Let me keep it balanced (equal weighting), which matches the "do well on both" instruction. Actually, let me reconsider one thing: the real test is only ~9% extrapolation (closer to T70 than T63). At T70, chosen gives cd=0.082, cl=0.033 , both excellent and both beat no-aug (cd 0.133, cl 0.080). So at realistic distance, chosen dominates on BOTH. Now, one more consideration for the FINAL model: I'll train on train+val combined. Let me also reconsider the cd_exp. The exponent -0.21 was fit on train data. It's robust physics. Keep. Let me also reconsider: should the final model's velocity aug upper bound be even a bit higher since train max is 75 and hidden could exceed 82? factor 1.30 × 75 = 97.5. That covers well beyond 82. If hidden went to, say, 90, 97.5 still covers. I think 1.30 is good. Going higher (1.5) risks the C_D degradation seen at T63 with strong aug. Keep 1.30. Now let me write the final training script. It should: 1. Load train + val, combine. 2. Compute feat_mean/std (over all points, physical) and targ_mean/std (over targets, physical) on combined data. 3. Train with chosen config. 4. Save checkpoint with state_dict + the 4 normalization tensors. For seed robustness: I'll train a few seeds and select the most "central" one via unsupervised agreement on public_test (closest to the mean prediction of the seeds), which reduces the chance of picking an outlier seed. This uses only inputs (no labels), so it's legitimate. Let me implement that. Actually, let me reconsider. The pred-ensemble was only marginally better than single (0.065 vs ~0.067). Seed variance at T70 was 0.062-0.075. For the final single model, picking a central/representative seed is a sensible hedge. I'll train, say, 5 seeds on the full data, compute each one's prediction on public_test (100 cases), find the ensemble-mean, and pick the seed whose predictions are closest (lowest mean NRMSE vs the ensemble centroid). That gives a representative, low-variance model. But wait , there's an even better option that's fully legitimate and likely better than any single seed: I noted soup (weight averaging) failed, and I can only submit one state_dict. So prediction-ensembling is off the table for submission. Central-seed selection is my best single-model hedge. Let me do that. Hmm, but actually, is central-seed selection clearly better than just fixing seed=0? It avoids pathological seeds. Given low variance, the risk is low either way. Central selection is a small, safe improvement. Let me do it with 5 seeds. Let me also build a final sanity evaluation: after training, check predictions on public_test are in a sane physical range (C_D ~0.007-0.05, C_L ~ -0.5 to 1.9), and check that the model's predictions vary sensibly with aoa. Let me also double-check: the checkpoint's feat_mean/feat_std must st …[truncated]
At aggressive extrapolation (T63) the chosen config still dominates no-aug overall (mean 0.085 vs 0.112), winning hugely on C_L (0.039 vs 0.111). β=0.3 ≈ β=0.2, so I'll keep β=0.3. The config is robust across thresholds. **Locked configuration:** 120 epochs, cosine LR (1e-3→1e-5), wd=1e-4; velocity augmentation ×U(0.92, 1.30) with C_D target scaled by factor^(−0.21) (Reynolds) and C_L unchanged; Huber loss (β=0.3). Now I'll write the final trainer: combine train+val, train 5 seeds, and select the most *representative* seed by agreement on public_test (unsupervised, inputs-only) as a variance hedge.
str_replace_based_edit_tool
command: create
path: /app/final_train.py
file_text: """Final trainer for the airfoil force-coefficient surrogate.

Strategy (validated on a velocity-extrapolation holdout built from the training
data, since the provided val split shares the training velocity range while the
scored set lies above it):

  * Train on train+val combined for maximum data.
  * Physics-grounded velocity augmentation: multiply each case's inlet velocity
    by f~U(0.92,1.30) and correct the C_D target by f**(-0.21) (the measured
    turbulent Reynolds exponent), leaving C_L unchanged (it is ~velocity
    invariant). This both teaches the correct weak velocity dependence and
    exposes the model to the higher-velocity regime it is scored on.
  * Huber loss (beta=0.3) in standardized target space -> robust to C_D outliers.
  * Cosine LR schedule, 120 epochs; plain final weights (EMA/SWA were worse).
  * Train several seeds and ship the most representative one (closest to the
    seed-ensemble mean on the public_test inputs) to hedge seed variance.
"""
from __future__ import annotations
import json, sys, time
from pathlib import Path
import numpy as np
import torch

APP = Path('/app'); sys.path.insert(0, str(APP))
from exp import (standardize_stats, train_model, predict, nrmse_metrics, CFG)
from dataset import load_split

CONFIG = dict(epochs=120, lr=1e-3, wd=1e-4, sched='cosine', lr_min=1e-5,
              vel_mult=0.08, vel_mult_hi=0.30, cd_exp=-0.21,
              loss='huber', huber_beta=0.3)
SEEDS = [0, 1, 2, 3, 4]


def main():
    t0 = time.time()
    ptr, ttr = load_split(APP / 'data' / 'train')
    pva, tva = load_split(APP / 'data' / 'val')
    points = torch.cat([ptr, pva], 0)
    targets = torch.cat([ttr, tva], 0)
    print(f'[final] combined train+val: {points.shape[0]} cases')

    fmean, fstd, tmean, tstd = standardize_stats(points, targets)
    print('[final] feat_mean', fmean.tolist())
    print('[final] feat_std ', fstd.tolist())
    print('[final] targ_mean', tmean.tolist(), 'targ_std', tstd.tolist())

    ptest, _ = load_split(APP / 'data' / 'public_test')

    # In-distribution val (for a sanity read only; NOT used for selection).
    states, val_preds, test_preds = [], [], []
    for sd in SEEDS:
        res, _ = train_model(points, targets, CONFIG, fmean, fstd, tmean, tstd, seed=sd)
        st = res['final']
        states.append(st)
        vp = predict(st, pva, fmean, fstd, tmean, tstd)
        tp = predict(st, ptest, fmean, fstd, tmean, tstd)
        val_preds.append(vp); test_preds.append(tp)
        m = nrmse_metrics(vp, tva)
        print(f'[final] seed={sd} in-dist val mean_nrmse={m["mean_nrmse_std"]:.4f} '
              f'cd={m["cd_nrmse_std"]:.4f} cl={m["cl_nrmse_std"]:.4f} '
              f'(t={time.time()-t0:.0f}s)', flush=True)

    # Pick the most representative seed: closest to the ensemble-mean prediction
    # on the public_test inputs (uses inputs only -> legitimate, label-free).
    test_stack = torch.stack(test_preds)            # [S, N, 2]
    centroid = test_stack.mean(0)
    # normalize each target channel by its spread so both count equally
    scale = centroid.std(0, keepdim=True).clamp_min(1e-8)
    dists = (((test_stack - centroid[None]) / scale[None]) ** 2).mean(dim=(1, 2))
    best = int(torch.argmin(dists).item())
    print('[final] seed centroid distances:', [round(float(d), 5) for d in dists])
    print(f'[final] selected representative seed = {SEEDS[best]}')

    # Report that seed's in-dist val and ensemble val for context.
    m_sel = nrmse_metrics(val_preds[best], tva)
    m_ens = nrmse_metrics(torch.stack(val_preds).mean(0), tva)
    print(f'[final] selected seed in-dist val mean_nrmse={m_sel["mean_nrmse_std"]:.4f}')
    print(f'[final] ensemble    in-dist val mean_nrmse={m_ens["mean_nrmse_std"]:.4f}')

    state = states[best]
    out_dir = APP / 'outputs'; out_dir.mkdir(parents=True, exist_ok=True)
    torch.save({
        'state_dict': {k: v.cpu() for k, v in state.items()},
        'feat_me
…[truncated]
output
New file created successfully at /app/final_train.py
Before launching the final (which takes ~5×200s = 1000s+), let me double-check the train_model final weights path and that predict works with the state from train_model (which includes BN buffers). The `res['final']` is `{k: v.detach().clone() for ... model.state_dict()}` , includes all params+buffers. predict loads it. Good. Let me do a quick smoke test of final_train with a tiny epochs override to ensure the whole pipeline (including save) works, before the long run. Let me temporarily run with epochs=2 and seeds=[0,1] via a quick monkeypatch through env, or just run a tiny inline test. Let me do an inline smoke test.
Before the long final run, let me smoke-test the whole pipeline end-to-end with tiny epochs to catch bugs.
bash
cd /app && python3 -c "
import final_train as ft
ft.CONFIG['epochs']=2
ft.SEEDS=[0,1]
ft.main()
" 2>&1 | tail -20
output
[final] combined train+val: 710 cases
[final] feat_mean [0.38364875316619873, 0.007897475734353065, 53.19941711425781, 0.07678442448377609]
[final] feat_std  [0.39559754729270935, 0.03333360701799393, 12.652849197387695, 0.09548104554414749]
[final] targ_mean [0.012753964401781559, 0.6618618965148926] targ_std [0.005126286298036575, 0.5782685279846191]
[final] seed=0 in-dist val mean_nrmse=0.2980 cd=0.3831 cl=0.2129 (t=5s)
[final] seed=1 in-dist val mean_nrmse=0.2875 cd=0.3797 cl=0.1953 (t=6s)
[final] seed centroid distances: [0.00397, 0.00397]
[final] selected representative seed = 0
[final] selected seed in-dist val mean_nrmse=0.2980
[final] ensemble    in-dist val mean_nrmse=0.2859
[final] wrote /app/outputs/model.pt (total 6s)
The pipeline works end-to-end. The 2-epoch model is bad (as expected). The checkpoint saves correctly. Now let me verify the checkpoint loads back into the exact architecture via build_model and produces predictions (simulating the grader). Let me write a verification script that mimics grading: load model.pt, build_model from config, load_state_dict (strict), standardize public_test inputs, forward, de-standardize, check ranges. Then launch the real final training in the background. Let me first write and run the verify against the current (smoke) checkpoint to ensure the loading contract works strictly.
The pipeline works and saves correctly. Let me write a grader-style verification that loads the checkpoint strictly into the fixed architecture and produces de-standardized predictions, then run the real training.
str_replace_based_edit_tool
command: create
path: /app/verify.py
file_text: """Grader-style verification: load the checkpoint strictly into the pinned
architecture, run a forward pass on public_test, de-standardize, sanity-check."""
from __future__ import annotations
import json, sys
from pathlib import Path
import torch

APP = Path('/app'); sys.path.insert(0, str(APP))
from candidate_model import build_model
from dataset import load_split

cfg = json.load(open(APP / 'task_config.json'))
ckpt = torch.load(APP / 'outputs' / 'model.pt', weights_only=True)

assert set(['state_dict', 'feat_mean', 'feat_std', 'targ_mean', 'targ_std']).issubset(ckpt), 'missing keys'
for k, n in [('feat_mean', 4), ('feat_std', 4), ('targ_mean', 2), ('targ_std', 2)]:
    t = ckpt[k]; assert tuple(t.shape) == (n,), f'{k} shape {t.shape}'
    assert torch.isfinite(t).all(), f'{k} not finite'
assert (ckpt['feat_std'] > 0).all() and (ckpt['targ_std'] > 0).all(), 'non-positive std'

model = build_model(cfg)
missing, unexpected = model.load_state_dict(ckpt['state_dict'], strict=True)
print('strict load OK; missing=', missing, 'unexpected=', unexpected)
model.eval()

fmean = ckpt['feat_mean'].view(1, 1, -1); fstd = ckpt['feat_std'].view(1, 1, -1)
tmean = ckpt['targ_mean'].view(1, -1); tstd = ckpt['targ_std'].view(1, -1)

for split in ['val', 'public_test']:
    pts, tgt = load_split(APP / 'data' / split)
    with torch.no_grad():
        out = model((pts - fmean) / fstd) * tstd + tmean
    print(f'== {split} (n={pts.shape[0]}) ==')
    print('  pred C_D: min=%.4f max=%.4f mean=%.4f' % (out[:, 0].min(), out[:, 0].max(), out[:, 0].mean()))
    print('  pred C_L: min=%.4f max=%.4f mean=%.4f' % (out[:, 1].min(), out[:, 1].max(), out[:, 1].mean()))
    assert torch.isfinite(out).all()
    if tgt is not None:
        import numpy as np
        for i, nm in enumerate(['C_D', 'C_L']):
            err = (out[:, i] - tgt[:, i]).numpy()
            rmse = float((err ** 2).mean() ** 0.5)
            nrmse = rmse / float(tgt[:, i].std())
            print(f'  {nm}: rmse={rmse:.5f} nrmse_std={nrmse:.4f}')
print('VERIFY OK')
output
New file created successfully at /app/verify.py
bash
cd /app && python3 verify.py 2>&1 | tail -25
output
strict load OK; missing= [] unexpected= []
== val (n=80) ==
  pred C_D: min=0.0084 max=0.0219 mean=0.0125
  pred C_L: min=-0.1036 max=1.5723 mean=0.7091
  C_D: rmse=0.00203 nrmse_std=0.3807
  C_L: rmse=0.12647 nrmse_std=0.2116
== public_test (n=100) ==
  pred C_D: min=0.0080 max=0.0212 mean=0.0114
  pred C_L: min=-0.2978 max=1.5303 mean=0.6754
VERIFY OK
The verification contract works: strict load OK, finite predictions, sane physical ranges even for the 2-epoch smoke model. Predictions on public_test: C_D 0.008-0.021 (physical), C_L -0.30 to 1.53 , reasonable ranges matching training distribution. Now let me launch the REAL final training (120 epochs, 5 seeds). This will take ~5 × 200s = ~1000s. Let me run in background and poll. Actually, let me reconsider the time per seed: the smoke test did 2 epochs × 2 seeds in 6s total → ~1.5s/epoch... no wait, 2 epochs for 2 seeds = 4 epoch-trainings in ~6s including overhead → ~1.3s per epoch on 710 samples. So 120 epochs ≈ 156s/seed. 5 seeds ≈ 780s + prediction overhead. Let me launch in background. Let me launch it now.
The contract holds: strict load succeeds, predictions are finite and in sane physical ranges. Now let me launch the real final training (120 epochs × 5 seeds) in the background.
bash
cd /app && export OMP_NUM_THREADS=16 && nohup python3 final_train.py > final.log 2>&1 &
echo "started final training pid $!"; sleep 5; cat final.log
output
started final training pid 33607
bash
cd /app && sleep 240 && cat final.log
output
[final] combined train+val: 710 cases
[final] feat_mean [0.38364875316619873, 0.007897475734353065, 53.19941711425781, 0.07678442448377609]
[final] feat_std  [0.39559754729270935, 0.03333360701799393, 12.652849197387695, 0.09548104554414749]
[final] targ_mean [0.012753964401781559, 0.6618618965148926] targ_std [0.005126286298036575, 0.5782685279846191]
[final] seed=0 in-dist val mean_nrmse=0.0559 cd=0.0765 cl=0.0353 (t=91s)
[final] seed=1 in-dist val mean_nrmse=0.0574 cd=0.0819 cl=0.0329 (t=151s)
[final] seed=2 in-dist val mean_nrmse=0.0568 cd=0.0808 cl=0.0329 (t=207s)
The final training is progressing well. In-distribution val (31-75 m/s) performance: - seed0: mean=0.0559, cd=0.0765, cl=0.0353 - seed1: mean=0.0574 - seed2: mean=0.0568 These are very consistent (~0.056-0.057), much better than the baseline. Note this is in-distribution val; the extrapolation (scored) should be in the ballpark of my T70 holdout results (~0.058). Good consistency. ~56s per seed now (seems faster after warmup, ~56-60s each). 2 more seeds → ~120s. Let me wait.
In-distribution val performance is strong and very consistent across seeds (~0.056–0.057). Let me wait for the final two seeds and the checkpoint write.
bash
cd /app && sleep 175 && cat final.log
output
[final] combined train+val: 710 cases
[final] feat_mean [0.38364875316619873, 0.007897475734353065, 53.19941711425781, 0.07678442448377609]
[final] feat_std  [0.39559754729270935, 0.03333360701799393, 12.652849197387695, 0.09548104554414749]
[final] targ_mean [0.012753964401781559, 0.6618618965148926] targ_std [0.005126286298036575, 0.5782685279846191]
[final] seed=0 in-dist val mean_nrmse=0.0559 cd=0.0765 cl=0.0353 (t=91s)
[final] seed=1 in-dist val mean_nrmse=0.0574 cd=0.0819 cl=0.0329 (t=151s)
[final] seed=2 in-dist val mean_nrmse=0.0568 cd=0.0808 cl=0.0329 (t=207s)
[final] seed=3 in-dist val mean_nrmse=0.0560 cd=0.0784 cl=0.0335 (t=260s)
[final] seed=4 in-dist val mean_nrmse=0.0712 cd=0.1080 cl=0.0344 (t=314s)
[final] seed centroid distances: [0.00146, 0.00112, 0.00048, 0.00069, 0.00112]
[final] selected representative seed = 2
[final] selected seed in-dist val mean_nrmse=0.0568
[final] ensemble    in-dist val mean_nrmse=0.0505
[final] wrote /app/outputs/model.pt (total 314s)
The final training completed. - Seeds 0-3 are consistent (~0.056-0.057), seed 4 is a bit worse (0.071). - The representative-seed selection picked seed 2 (closest to the public_test ensemble centroid), which has in-dist val mean_nrmse=0.0568 , a solid, central choice. It correctly avoided seed 4 (the outlier at 0.071). - Ensemble would've been 0.0505 but I can't ship an ensemble. The checkpoint is written. Let me verify it with the grader-style script. Note: seed 2 (selected) has in-dist val 0.0568, cd=0.0808, cl=0.0329. The selection via centroid distance on public_test chose the most representative model, which is a good variance hedge and avoided the bad seed 4. Let me run verify.py on the final checkpoint.
Final training completed. The representative-seed selection correctly picked a central seed (seed 2, val 0.0568) and **avoided the outlier seed 4** (0.071). Let me verify the final checkpoint with the grader-style script.
bash
cd /app && python3 verify.py 2>&1 | tail -25
output
strict load OK; missing= [] unexpected= []
== val (n=80) ==
  pred C_D: min=0.0076 max=0.0338 mean=0.0128
  pred C_L: min=-0.4182 max=1.8086 mean=0.6825
  C_D: rmse=0.00043 nrmse_std=0.0803
  C_L: rmse=0.01952 nrmse_std=0.0327
== public_test (n=100) ==
  pred C_D: min=0.0072 max=0.0278 mean=0.0119
  pred C_L: min=-0.5005 max=1.7121 mean=0.6760
VERIFY OK
The final checkpoint: - Strict load OK. - In-dist val: C_D nrmse_std=0.0803, C_L nrmse_std=0.0327, mean=0.0568. (Note: val here is trained-on data since I combined train+val for the final model, so these numbers are optimistic , they include training data. That's fine; it's just a sanity check.) - public_test predictions: C_D 0.0072-0.0278 (physical, sane), C_L -0.50 to 1.71 (sane). Means are reasonable. Wait , the val set was INCLUDED in final training (train+val combined), so the val metrics here are on training data, hence very low (0.057). Not a true generalization estimate. My true extrapolation estimate comes from the pseudo-holdout experiments (~0.058 at T70, which used proper held-out high-velocity data). Good. Let me now do a final robustness sanity check specific to the extrapolation: let me verify the model's predictions behave sensibly as velocity increases beyond the training range. I'll take public_test cases and see that predictions don't blow up, and that C_D decreases slightly with velocity (Reynolds) while C_L stays roughly constant (as physics dictates). This confirms the model learned the right velocity behavior and extrapolates smoothly. Let me test: take the public_test inputs, and for a few cases, artificially sweep velocity from 75 up to 90 and plot predicted C_D, C_L. I expect C_D to decrease mildly (~vel^-0.21) and C_L to stay ~flat. This validates safe extrapolation.
The checkpoint passes the grader-style contract with sane physical prediction ranges. (Note: val was part of the final training set, so those numbers are optimistic , my true extrapolation estimate is the ~0.058 from the held-out high-velocity experiments.) Let me do one more physics sanity check: confirm the model extrapolates *smoothly* and correctly beyond the training velocity , C_D should fall gently (~Reynolds) and C_L stay roughly flat as I push velocity up.
bash
cd /app && python3 -c "
import json, torch, numpy as np, sys
sys.path.insert(0,'.')
from candidate_model import build_model
from dataset import load_split
cfg=json.load(open('task_config.json'))
ck=torch.load('outputs/model.pt', weights_only=True)
m=build_model(cfg); m.load_state_dict(ck['state_dict']); m.eval()
fm=ck['feat_mean'].view(1,1,-1); fs=ck['feat_std'].view(1,1,-1); tm=ck['targ_mean'].view(1,-1); ts=ck['targ_std'].view(1,-1)
pts,_=load_split('data/public_test')
def pred(p):
    with torch.no_grad(): return (m((p-fm)/fs)*ts+tm)
# take 8 cases, sweep velocity 70..95, report mean predicted CD, CL trend
base=pts[:8].clone()
print('vel   meanC_D   meanC_L   (sweep on 8 public_test cases)')
cds=[]
for v in [65,70,75,80,85,90,95]:
    p=base.clone(); p[:,:,2]=v
    o=pred(p); cds.append(o[:,0].mean().item())
    print(f'{v:3d}   {o[:,0].mean():.5f}   {o[:,1].mean():.4f}')
# compare CD ratio 75->90 to reynolds f^-0.21
r=(cds[5]/cds[2]); print('CD(90)/CD(75)=%.3f  ideal (90/75)^-0.21=%.3f'%(r,(90/75)**-0.21))
print('check predictions finite & positive CD across sweep:', all(c>0 for c in cds))
"
output
vel   meanC_D   meanC_L   (sweep on 8 public_test cases)
 65   0.01185   0.6598
 70   0.01169   0.6595
 75   0.01154   0.6590
 80   0.01139   0.6593
 85   0.01125   0.6605
 90   0.01112   0.6622
 95   0.01101   0.6630
CD(90)/CD(75)=0.964  ideal (90/75)^-0.21=0.962
check predictions finite & positive CD across sweep: True
This is an excellent confirmation. As velocity increases from 65 to 95 m/s (including well beyond the training max of 75): - Predicted C_D decreases smoothly and monotonically: 0.01185 → 0.01101. - The ratio C_D(90)/C_D(75) = 0.964, almost exactly matching the ideal Reynolds power law (90/75)^-0.21 = 0.962! The model learned the correct physical velocity dependence and extrapolates it faithfully. - Predicted C_L stays essentially flat (0.659 → 0.663), as physics dictates (velocity-invariant). - All predictions remain finite and positive across the entire sweep. This confirms the model extrapolates smoothly and physically correctly beyond the training velocity range , exactly what the task demands. The velocity augmentation with the Reynolds correction worked as intended. The solution is complete and robust. Let me now do a final review: 1. Checkpoint written to /app/outputs/model.pt ✓ 2. Contains state_dict, feat_mean, feat_std, targ_mean, targ_std ✓ 3. All 4 normalization tensors present, correct shapes (4,4,2,2), finite, positive std ✓ 4. Loads strictly into the fixed architecture ✓ 5. Produces sane, finite predictions ✓ 6. Extrapolates correctly in velocity (the key task requirement) ✓ Let me clean up and do a final confirmation of the output file, and verify I didn't leave the smoke-test checkpoint (the final_train ran fully and overwrote it). The final.log shows it wrote the real one at t=314s. And verify.py showed good val metrics (0.057), consistent with a fully-trained model, not the 2-epoch smoke one. Good. Let me also make sure there's nothing writing to /tmp/out (I haven't, per instructions). And confirm the outputs directory contents. Let me reconsider whether I should reconsider the seed selection. Seed 2 was selected. Its in-dist val is 0.0568 (but that includes training data). The selection was based on centroid distance on public_test inputs , legitimate. It avoided the bad seed 4. This is fine. One consideration: could I do better by picking the seed based on the extrapolation holdout instead? But the final model trains on ALL data, so I can't evaluate its extrapolation directly. The centroid selection is the best label-free approach. I'm confident. Let me also double check: is there any risk that the grader uses a different normalization direction? The task says: "feat_mean, feat_std: length-4 tensors that standardize the point features before the forward pass" and "targ_mean, targ_std: length-2 tensors that map the model's outputs back into physical coefficient units." So grader computes: x_std = (x - feat_mean)/feat_std; out = model(x_std); pred = out*targ_std + targ_mean. That's exactly how I trained and how verify.py does it. Everything is consistent. Let me do a final listing and a clean summary. Let me verify the final output file exists and is valid one more time, and show its keys/shapes/dtypes.
This is the decisive confirmation. As velocity sweeps from 65 up to 95 m/s (well beyond the training max of 75): - **C_D decreases smoothly and monotonically**, with C_D(90)/C_D(75) = 0.964 , almost exactly the ideal Reynolds law (90/75)^(−0.21) = 0.962. - **C_L stays essentially flat** (0.659→0.663), as physics dictates. - All predictions remain finite and positive. The model learned the correct physical velocity dependence and extrapolates it faithfully , exactly what the task requires. Let me do a final inspection of the deliverable.
bash
cd /app && ls -la outputs/ && python3 -c "
import torch
ck=torch.load('outputs/model.pt', weights_only=True)
print('keys:', list(ck.keys()))
for k in ['feat_mean','feat_std','targ_mean','targ_std']:
    print(f'  {k}: shape={tuple(ck[k].shape)} dtype={ck[k].dtype} vals={[round(float(x),4) for x in ck[k]]}')
print('state_dict tensors:', len(ck['state_dict']))
print('total params:', sum(v.numel() for v in ck['state_dict'].values() if v.dtype.is_floating_point))
"
output
total 347
drwxr-sr-x 2 h2tagent h2tagent   4096 Jun 19 22:51 .
drwxrws--- 5 h2tagent h2tagent   4096 Jun 19 22:51 ..
-rw-r--r-- 1 h2tagent h2tagent 346611 Jun 19 22:57 model.pt
keys: ['state_dict', 'feat_mean', 'feat_std', 'targ_mean', 'targ_std']
  feat_mean: shape=(4,) dtype=torch.float32 vals=[0.3836, 0.0079, 53.1994, 0.0768]
  feat_std: shape=(4,) dtype=torch.float32 vals=[0.3956, 0.0333, 12.6528, 0.0955]
  targ_mean: shape=(2,) dtype=torch.float32 vals=[0.0128, 0.6619]
  targ_std: shape=(2,) dtype=torch.float32 vals=[0.0051, 0.5783]
state_dict tensors: 27
total params: 84738
The deliverable is complete and validated. Here's a summary of what I did and why. ## Outcome I trained the pinned PointNet and wrote `/app/outputs/model.pt` containing `state_dict` plus all four normalization tensors (`feat_mean/std` length-4, `targ_mean/std` length-2). It loads **strictly** back into the unmodified architecture and produces finite, physically-sane `[C_D, C_L]` predictions. ## The core problem and my diagnosis The scored cases sit entirely **above** the training velocity range (public_test is 75–82 m/s vs. training 31–75), and the provided `val` split shares the training range , so **`val` does not test the extrapolation that actually matters**. I built a **velocity-based extrapolation holdout** from the training data (train on low velocities, evaluate on the highest) to measure the real objective. From the data I established the governing physics: - **C_L** is essentially velocity-invariant (aoa explains ~89% of variance; velocity exponent ≈ −0.015). - **C_D** follows a clean Reynolds law, **C_D ∝ velocity^(−0.21)** , matching the classic turbulent skin-friction exponent (~−0.2). ## What I changed from the baseline (training only , architecture untouched) - **Physics-grounded velocity augmentation**: scale each case's inlet velocity by f∼U(0.92, 1.30), correct the C_D target by f^(−0.21), and leave C_L unchanged. This both teaches the correct weak velocity dependence and exposes the model to the higher-velocity regime it's scored on. - **Huber loss (β=0.3)** in standardized target space , robust to the C_D outliers that were inflating RMS. - **Cosine schedule, 120 epochs**; plain final weights (I tested EMA/SWA and weight-averaging "soups" , all were worse here). - Trained on **train+val combined**, 5 seeds, shipping the **most representative seed** (closest to the seed-ensemble mean on public_test inputs , label-free), which correctly avoided an outlier seed. ## Evidence it works On the realistic extrapolation holdout, mean NRMSE improved from **0.106 (baseline) → 0.058**, winning on *both* targets (C_D 0.133→0.082, C_L 0.080→0.033). A velocity sweep on held-out cases confirms the model extrapolates **smoothly and physically**: beyond the training range, predicted C_D(90)/C_D(75)=0.964 ≈ the ideal 0.962, while C_L stays flat. One caveat to flag honestly: the single-checkpoint contract rules out prediction ensembling (which was marginally better), and my extrapolation numbers come from an internal holdout rather than the true hidden set, so treat them as estimates. The behavior is balanced across drag and lift as requested, rather than trading one off against the other.
Final diff , what the agent changed

No file changes, the agent left the workspace untouched.

Verifier output , the proof behind the reward
tests/test.sh
# SyncVals normalized verifier summary
# task: airfrans-high-reynolds-drag-extrapolation
# attempt: 5  status: completed  raw_score: 0.46
# reward rule: continuous: score 0.46 < 0.5
# => reward = 0.0  (FAIL)
#
# Note: these tasks score via an external hidden grader; no pytest/verifier
# block is embedded in the agent transcript. The block below is the last
# sizable tool-output captured in the run (supporting evidence).
----------------------------------------------------------------------
total 347
drwxr-sr-x 2 h2tagent h2tagent   4096 Jun 19 22:51 .
drwxrws--- 5 h2tagent h2tagent   4096 Jun 19 22:51 ..
-rw-r--r-- 1 h2tagent h2tagent 346611 Jun 19 22:57 model.pt
keys: ['state_dict', 'feat_mean', 'feat_std', 'targ_mean', 'targ_std']
  feat_mean: shape=(4,) dtype=torch.float32 vals=[0.3836, 0.0079, 53.1994, 0.0768]
  feat_std: shape=(4,) dtype=torch.float32 vals=[0.3956, 0.0333, 12.6528, 0.0955]
  targ_mean: shape=(2,) dtype=torch.float32 vals=[0.0128, 0.6619]
  targ_std: shape=(2,) dtype=torch.float32 vals=[0.0051, 0.5783]
state_dict tensors: 27
total params: 84738

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_951a5d1420f24896. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_951a5d1420f24896 · verifier authoritative; classifier explanatory.