git:20260818.7646306 to git:20260818.8af3059

---

name: sim-cli

description: Cross-solver operating discipline for sim-cli workflows — tool choice, input classification, acceptance semantics, and escalation rules that apply across solvers. Use alongside the solver's own plugin skill, which is self-contained for solver-specific work; this skill carries only the shared rules.

---

# 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.

| Model | Used by | Lifecycle |

|---|---|---|

| **Persistent session** | Drivers that hold a live process open | `sim connect → sim exec × N → sim inspect → sim disconnect` |

| **sim-wrapped one-shot batch** | Plugin wrappers that add linting, profile-aware invocation, parsing, history, or safer execution | `sim check → sim run → parse_output/logs → evaluate` |

| **Native/tool one-shot batch** | Ready solver decks/scripts, vendor batch commands, project pipelines, or post-processing tools where native execution is the right primitive | version/profile probe → native command/script → parse artifacts/logs → evaluate |

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?

| Category | Rule | Examples |

|---|---|---|

| **A — physical decisions** | **Must ask if absent.** Non-negotiable. | Geometry, materials, boundary/initial conditions, physics-model choices, the acceptance criterion |

| **B — operational** | **May default — must disclose.** Affects runtime/convenience, not what the simulation represents. | `--processors`, `--ui-mode`, `--workspace`, smoke-test iteration counts, log verbosity |

| **C — file-derivable** | **Infer from the actual files** via a diagnostic `sim exec`, solver-native inspection command, or artifact parser — not from a similar example. Confirm if a downstream decision depends on it. | Mesh cell count, boundary names/types, fields present in a result file, material IDs |

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

---

## 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.

| `sim serve` started from… | Headless / CLI drivers | GUI-capable drivers |

|---|---|---|

| Logged-in Windows desktop (Windows Terminal / RDP / Task Scheduler "run only when user is logged on" + interactive) | ✅ works | ✅ works — windows are visible; `gui` can find / click / screenshot them |

| SSH session (`ssh <host>` then `sim serve …`) | ✅ works | ❌ silent breakage — windows launch in a non-interactive session with no display surface; `gui` finds zero windows, screenshots come back black |

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`](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.