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Get Started Free →Plan and control time-step policies for simulations. Use when coupling CFL/physics limits with adaptive stepping, ramping initial transients, scheduling outputs/checkpoints, or planning restart strategies for long runs.
.claude/skills/time-stepping/SKILL.md| Test case | Without → With | Effect | Δ tokens | Δ turns |
|---|---|---|---|---|
| case-06 | ✗→✓ | ▲ Improved | — | — |
| case-10 | ✗→✓ | ▲ Improved | — | — |
| case-13 | ✗→✓ | ▲ Improved | — | — |
| case-19 | ✗→✓ | ▲ Improved | — | — |
| case-01 | ✗→✓ | ▲ Improved | — | — |
Provide a reliable workflow for choosing, ramping, and monitoring time steps plus output/checkpoint cadence.
| Input | Description | Example | |-------|-------------|---------| | Stability limits | CFL/Fourier/reaction limits | dt_max = 1e-4 | | Target dt | Desired time step | 1e-5 | | Total run time | Simulation duration | 10 s | | Output interval | Time between outputs | 0.1 s | | Checkpoint cost | Time to write checkpoint | 120 s |
Is stability limit known?
├── YES → Use min(dt_target, dt_limit × safety)
└── NO → Start conservative, increase adaptively
Need ramping for startup?
├── YES → Start at dt_init, ramp to dt_target over N steps
└── NO → Use dt_target from start| Problem Type | Ramp Steps | Initial dt | |--------------|------------|------------| | Smooth IC | None needed | Full dt | | Sharp gradients | 5-10 | 0.1 × dt | | Phase change | 10-20 | 0.01 × dt | | Cold start | 10-50 | 0.001 × dt |
| Script | Key Outputs | |--------|-------------| | scripts/timestep_planner.py | dt_limit, dt_recommended, ramp_schedule | | scripts/output_schedule.py | output_times, interval, count | | scripts/checkpoint_planner.py | checkpoint_interval, checkpoints, overhead_fraction |
scripts/timestep_planner.pyscripts/output_schedule.pyscripts/checkpoint_planner.pyUser: I'm running a 10-hour phase-field simulation. How often should I checkpoint?
Agent workflow:
bash python3 scripts/checkpoint_planner.py --run-time 36000 --checkpoint-cost 120 --max-lost-time 1800 --json
bash# Plan time stepping with ramping python3 scripts/timestep_planner.py --dt-target 1e-4 --dt-limit 2e-4 --safety 0.8 --ramp-steps 10 --json # Schedule output times python3 scripts/output_schedule.py --t-start 0 --t-end 10 --interval 0.1 --json # Plan checkpoints for long run python3 scripts/checkpoint_planner.py --run-time 36000 --checkpoint-cost 120 --max-lost-time 1800 --json
| Error | Cause | Resolution | |-------|-------|------------| | dt-target must be positive | Invalid time step | Use positive value | | t-end must be > t-start | Invalid time range | Check time bounds | | checkpoint-cost must be < run-time | Checkpoint too expensive | Reduce checkpoint size |
| Observation | Meaning | Action | |-------------|---------|--------| | dt stable at target | Good | Continue | | dt shrinking | Stability issue | Check CFL, reduce target | | dt oscillating | Borderline stability | Add safety factor |
| Overhead | Acceptability | |----------|---------------| | < 1% | Excellent | | 1-5% | Good | | 5-10% | Acceptable | | > 10% | Too frequent, increase interval |
references/cfl_coupling.md - Combining multiple stability limitsreferences/ramping_strategies.md - Startup policiesreferences/output_checkpoint_guidelines.md - Cadence rules| Case | Status | Duration (ms) | Turns | Tokens | Tool calls | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Without | With | Δ | Without | With | Δ | Without | With | Δ | Without | With | Δ | ||
case-06 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-10 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-13 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-19 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-04 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-17 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-21 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-01 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-20 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-09 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-05 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-22 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-18 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-08 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-03 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-14 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-02 | pass→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-11 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-16 | pass→pass | — | — | — | — | — | — | — | — | — | — | — | — |
case-15 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-12 | fail→fail | — | — | — | — | — | — | — | — | — | — | — | — |
case-07 | fail→pass | — | — | — | — | — | — | — | — | — | — | — | — |
DecimalAI ran this skill against gemini-3.6-flash twice over the same eval suite — once with the skill loaded and once without — and compared the two runs case by case. 22 cases were attempted, and 21 counted toward the lift figure. The other 1 produced results that are not comparable between the two arms, so they are excluded from the headline rather than averaged into it. The headline lift of +55 percentage points is the difference between those two pass rates over the 21 comparable cases.
The per-case answers from this run were removed by the retention sweep, so the case table below shows the verdicts without the text either arm produced. The counts above were recorded at the time and are unaffected. Answers are now kept for 180 days.
Other measured skills in the registry, with their headline benchmark lift.