Sim CLI

sim-cli

You are working in a sim-cli-enabled solver workflow. Use the sim runtime where it adds control and observability, and compose solver-native tools directly where they are the right primitive. This skill carries the cross-solver discipline — the rules that hold across sim-cli workflows, regardless of which solver you drive.

The solver's plugin skill is self-contained for solver-specific work: solver hard constraints, dependency chains, snippets, workflows, SDK/solver notes. It does not depend on loading this skill — but it should stay consistent with the discipline below. If a rule applies to more than one solver, it belongs here, not in a plugin skill.

Execution models

The plugin skill tells you which model the solver uses. Choose the narrowest correct execution primitive; sim-cli is composable, not a universal wrapper.

sim-cli does not try to wrap every solver operation, executable flag, vendor batch mode, or post-processing script. Use sim when it adds a stable control plane: solver discovery and profile checks, live sessions, bounded exec / inspect loops, history/log capture, parsing, screenshots, or shared agent discipline. If the artifact is already a solver-native deck/script and the solver's own batch command is the right execution primitive, call that native command directly instead of forcing it through sim run. Preserve stdout/stderr, generated files, and acceptance evidence just as carefully.

Use sim run when the plugin skill says it is the canonical one-shot path or when the wrapper adds real value. Otherwise, keep the sim-cli discipline while composing the solver's native tools directly.

The loop, any model: classify inputs and get the missing Category A values from the user (including the acceptance criterion) → choose the execution primitive → run a Step-0 version/profile probe (sim inspect session.versions for persistent sessions; sim check <solver>, plugin guidance, or native --version / license probe for one-shot work) → execute one bounded step at a time → inspect last.result or parse the native logs/artifacts between steps → evaluate against the acceptance criterion → sim disconnect if a persistent session was opened. On any failure, stop and report — do not silently retry.

Hard constraints (shared sim-cli discipline)

1. Never invent Category A defaults. Physical decisions — geometry, materials, boundary conditions, the acceptance criterion — must come from the user. "Just use defaults" / "just run it" does not override this; treat it as a missing input and ask.
2. Step-0 version/profile probe is mandatory. After sim connect, call sim inspect session.versions and use the returned profile / active_sdk_layer / active_solver_layer to pick the right files in the plugin skill. Treat solver_version as active-runtime evidence only when version_source is active_runtime; a detected installation is not proof that the same version was launched. If the runtime version is unreported or has no compatible profile, stop before applying version-specific guidance. Before sim run or native one-shot execution, run the relevant probe for that path (sim check <solver>, plugin guidance, or the solver's native --version / license check). If a required profile is empty, unknown, or deprecated — stop.
3. Acceptance ≠ exit code. A sim run / sim exec / native solver command can return success and still be physically wrong. Always validate against an outcome-based, bounded, measurable criterion — not "the solver ran".
4. Never silently retry a failed step. Report stderr, stdout, and run_count / completion state / relevant artifact state; let the user decide the next move.
5. Reference example values are not defaults. Values in any examples/ directory describe a specific published test case. Offer them explicitly if useful, but wait for the user's confirmation before adopting them.

Input classification

Every task starts with: which inputs must the user supply, which may I default, which can I derive from the files in front of me?

Do not start until every Category A field has an explicit value from the user.

First causal failure gate

When a workflow fails, locate the first failed stage before changing the model: environment/license -> launch or attach -> file import -> model setup -> mesh or build -> solve -> postprocess/export. Preserve the first new error, the exact entrypoint, active version/profile, and relevant artifact identity; later errors may only be consequences.

Run the smallest stage-specific probe that can confirm or reject one cause. Do not change physics, boundary conditions, mesh controls, or solver settings to work around an unproven environment, import, or setup failure. Retry only after naming the hypothesis and the evidence expected to change.

Where sim serve runs (Windows session-context foot-gun)

If you reach a remote sim host via sim --host <host> or SIM_HOST, how the operator started sim serve changes which drivers actually work. This is purely a Windows concern — Linux and macOS don't isolate display sessions the same way.

If the host advertises tools: ["gui"] but gui.find(...) returns nothing for windows you have strong reason to believe exist, do not retry — surface "the server may have been started from a non-interactive session" and ask the operator to restart sim serve from a desktop session. The agent never starts sim serve itself.

See gui/SKILL.md for the full GUI actuation API.

Long-running and multi-stage workflows

Do not wait for or request a dedicated per-task primitive (a resumable-sweep API, an auto-coupling feature, etc.) when the generic primitives already suffice. Bounded exec/run calls, session.health / solve-progress inspection, and the solver's own retained project/session state are enough to drive a long sweep, a multi-stage build, or a staged multi-physics coupling yourself, one bounded step at a time. Reach for a new dedicated primitive only when a real session hits a generic gap (no timeout guard, no liveness check, no process cleanup) — not to shortcut a specific workflow that a generic loop already covers.