deltatau-audit 0.3.6

Time Robustness Audit for RL agents — measures timing reliance, deployment robustness, and stress resilience

deltatau-audit

Time Robustness Audit for RL agents.

Evaluates whether an RL agent breaks when the environment's timing changes — the kind of failure that silently appears in deployment but never shows up in training.

Try it in 30 seconds

pip install "deltatau-audit[demo]"
python -m deltatau_audit demo cartpole

No GPU. No MuJoCo. Just pip install and run. You'll see a Before/After comparison:

Scenario	Before (Baseline)	After (Speed-Randomized)	Change
5x speed	12%	49%	+37pp
Speed jitter	66%	115%	+49pp
Observation delay	82%	95%	+13pp
Mid-episode spike	23%	62%	+39pp
Deployment	FAIL (0.23)	DEGRADED (0.62)	+0.39

The standard agent collapses under timing perturbations. Speed-randomized training dramatically improves robustness. Full HTML reports with charts are generated in demo_report/.

The same pattern at MuJoCo scale: HalfCheetah PPO

A PPO agent trained to reward ~990 on HalfCheetah-v5 shows even more catastrophic timing failures — all 4 scenarios statistically significant (95% bootstrap CI):

Scenario	Return (% of nominal)	95% CI	Drop
Observation delay (1 step)	3.8%	[2.4%, 5.2%]	-96%
Speed jitter (2 +/- 1)	25.4%	[23.5%, 27.8%]	-75%
5x speed (unseen)	-9.3%	[-10.6%, -8.4%]	-109%
Mid-episode spike (1->5->1)	90.9%	[86.3%, 97.8%]	-9%

A single step of observation delay destroys 96% of performance. The agent goes negative at 5x speed.

View interactive report | Download report ZIP

Speed-randomized training fixes the problem

Scenario	Before (Standard)	After (Speed-Randomized)	Change
Observation delay	2%	148%	+146pp
Speed jitter	28%	121%	+93pp
5x speed (unseen)	-12%	38%	+50pp
Mid-episode spike	100%	113%	+13pp
Deployment	FAIL (0.02)	PASS (1.00)
Quadrant	deployment_fragile	deployment_ready

View Before report | View After report

Reproduce HalfCheetah results

pip install "deltatau-audit[sb3,mujoco]"
git clone https://github.com/maruyamakoju/deltatau-audit.git
cd deltatau-audit
python examples/audit_halfcheetah.py              # standard PPO audit (~30 min)
python examples/train_robust_halfcheetah.py        # train robust PPO (~30 min)
python examples/audit_before_after.py              # Before/After comparison

Or download pre-trained models from Releases.

Install

pip install deltatau-audit            # core
pip install "deltatau-audit[demo]"    # + CartPole demo (recommended start)
pip install "deltatau-audit[sb3,mujoco]"  # + SB3 + MuJoCo environments

Audit Your Own SB3 Model

from stable_baselines3 import PPO
from deltatau_audit.adapters.sb3 import SB3Adapter
from deltatau_audit.auditor import run_full_audit
from deltatau_audit.report import generate_report
import gymnasium as gym

model = PPO.load("my_model.zip")
adapter = SB3Adapter(model)

result = run_full_audit(
    adapter,
    lambda: gym.make("HalfCheetah-v5"),
    speeds=[1, 2, 3, 5, 8],
    n_episodes=30,
)
generate_report(result, "my_audit/", title="My Agent Audit")

What It Measures

Badge	What it tests	How
Reliance	Does the agent use internal timing?	Tampers with internal Dt, measures value prediction error
Deployment	Does the agent survive realistic timing changes?	Jitter, observation delay, mid-episode speed spikes
Stress	Does the agent survive extreme timing changes?	5x speed (unseen during training)

Agents without internal timing (standard PPO, SAC, etc.) get Reliance: N/A — only Deployment and Stress are tested.

Rating Scale

Rating	Return Ratio	Meaning
PASS	> 95%	Production ready
MILD	> 80%	Minor degradation
DEGRADED	> 50%	Significant loss
FAIL	<= 50%	Agent breaks

All return ratios include bootstrap 95% confidence intervals with significance testing.

CI Mode

python -m deltatau_audit demo cartpole --ci --out ci_report/
# exit 0 = pass, exit 1 = warn (stress), exit 2 = fail (deployment)

Outputs ci_summary.json and ci_summary.md for pipeline gates and PR comments.

Custom Adapters

Implement AgentAdapter (see deltatau_audit/adapters/base.py):

from deltatau_audit.adapters.base import AgentAdapter

class MyAdapter(AgentAdapter):
    def reset_hidden(self, batch=1, device="cpu"):
        return torch.zeros(batch, hidden_dim)

    def act(self, obs, hidden):
        # Returns: (action, value, hidden_new, dt_or_None)
        ...
        return action, value, hidden_new, None

Built-in adapters: SB3Adapter (PPO/SAC/TD3/A2C), SB3RecurrentAdapter (RecurrentPPO), InternalTimeAdapter (Dt-GRU models).

Comparing Results

python -m deltatau_audit diff before/summary.json after/summary.json --out comparison.md