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Simulation sandbox

Skill marktantongco/opencodelinux/skills/simulation-sandbox

Test scenarios, decisions, and code without real-world consequences. Use for what-if analysis, prototyping, stress-testing, and war-gaming strategic decisions.From its SKILL.md

Install
npx -y skills add marktantongco/opencodelinux --skill simulation-sandbox

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SKILL.md

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Simulation Sandbox

Context

Activate this skill when the user needs to test a scenario, decision, or piece of code without real-world consequences. This includes:

  • Evaluating architectural decisions before implementation
  • Stress-testing business logic under hypothetical conditions
  • Exploring "what-if" scenarios (market changes, load spikes, failure modes)
  • Prototyping algorithms or data pipelines with synthetic data
  • War-gaming strategic decisions (competitor moves, pricing changes)
  • Testing code behavior with edge-case inputs

Do not use when the user needs real data analysis, wants to execute actual code in production, or requires factual reporting rather than speculative modeling.

Instructions

Step 1: Define the Simulation Scope

  • What is being simulated (system, process, decision, code)
  • Why it is being simulated (question to answer, risk to evaluate)
  • Boundaries (what is in scope and out of scope)
  • Key metrics (what success/failure looks like)

Step 2: Establish Parameters and Assumptions

  • Input values (synthetic, estimated, or from user)
  • Environmental conditions (load, time period, external factors)
  • Assumptions that simplify the model (and their potential impact)
  • Fixed variables vs. variables to be tested across ranges

Step 3: Build the Simulation Model

  • Describe the initial state
  • Define the rules/logic that govern each step
  • Identify feedback loops or cascading effects
  • Set the number of iterations or time steps

Step 4: Run Scenarios

  • Baseline: Expected/normal conditions
  • Best case: Optimistic but plausible inputs
  • Worst case: Pessimistic but plausible inputs
  • Edge cases: Boundary conditions, extreme values
  • Stress test: Push parameters beyond normal range

Step 5: Observe and Record Outcomes

For each scenario capture:

  • Key metric values at each time step
  • Points of failure or unexpected behavior
  • Patterns that emerge across scenarios

Step 6: Report Findings

  • Executive summary (2–3 sentences)
  • Scenario comparison
  • Key findings and patterns
  • Sensitivity analysis
  • Limitations of the simulation
  • Recommended next steps

Step 7: Label Everything

  • All numbers prefaced with [SIMULATED]
  • Frame as "In this simulation model..." or "Under these parameters..."
  • Never present simulated data as empirical fact

Constraints

  1. Always label simulated outputs. Use [SIMULATED] tags prominently.
  2. State limitations explicitly. Every simulation has blind spots — name them.
  3. Use plausible parameters. Even stress tests should use values that could theoretically occur.
  4. Never claim predictive accuracy. Use language like "suggests," "indicates," "under these conditions."
  5. Separate signal from noise. Call out if a result is driven by a simplifying assumption.
  6. Complete the full cycle. Every simulation must include Steps 1–7.

Examples

Example 1: API Load Testing

User: "Will our API survive 10x traffic?"

Output:

═══ SIMULATION: API Load Capacity Test ═══

Step 1 — Scope
  System: REST API, question: At what traffic does degradation begin?
  Metrics: P50/P99 latency, error rate (%)

Step 2 — Parameters
  - Baseline: 500 req/sec, P50=45ms, P99=120ms, error=0.1%
  - [ASSUMPTION] Infrastructure scales vertically

Step 3 — Model
  Each step = 1 second. Logic: req/sec → pool util → queue → latency.
  Failure trigger: queue > 100 or error > 5%.

Step 4 — Scenarios
  ┌────────────┬────────┬─────────┬─────────┬─────────┐
  │ Scenario  │req/sec │P50(ms)  │P99(ms)  │Error Rate│
  ├────────────┼────────┼─────────┼─────────┼─────────┤
  │ Baseline  │ [SIM]500│[SIM]45  │[SIM]120 │[SIM]0.1%│
  │ 3x load   │ [SIM]1500│[SIM]62 │[SIM]210 │[SIM]0.3%│
  │ 10x load  │ [SIM]5000│[SIM]340│[SIM]2100│[SIM]8.7%│
  └────────────┴────────┴─────────┴─────────┴─────────┘

Step 5 — Findings
  [SIMULATED] Degradation begins between 3x–5x load.
  Connection pool saturation is the primary bottleneck.

Step 6 — Recommendation
  Horizontal scaling + connection pooling before 5x load.

═══ END SIMULATION ═══

What ships with it

Read from the repository

Just SKILL.md. No reference files, no scripts.

Gives 0 of the 12 instructions most test skills give in ~1.1k tokens

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Said here and by no other author read

  • define the simulation scope
  • establish parameters and assumptions
  • build the simulation model
  • run baseline, edge, and stress scenarios
  • observe and record outcomes
  • report findings and recommended next steps

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.

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