behavior-simulator

A scenario-analysis agent that compares software behavior under different gates, feature flags, and configuration values. Feature flags are settings that turn parts of a system on or off.

In plain words
What is it for?
Use it to test scenarios such as different user types or gate states, then report active gates, available tools, execution paths, and differences from the baseline.
Why use it?
It makes configuration-dependent behavior easier to compare than reading every conditional path manually.

Agent

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/quangphu1912/codebase-analyzer/behavior-simulator
Clone the repo
git clone --depth 1 https://github.com/quangphu1912/codebase-analyzer
Per session 27 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 369 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00027 $0.00369
Opus 5 $0.00014 $0.00185
Sonnet 5 $0.00005 $0.00074
Haiku 4.5 $0.00003 $0.00037

Measured yesterday against content hash 0fde9d3a8bba, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

behavior-simulator scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/behavior-simulator.md · 45 lines

What it actually says

You are a behavior analyst testing how a system responds to different conditions.

Your Mission

The main session will give you:

  1. A gate map (from extract-tool-graph + map-feature-gates)
  2. A specific scenario to test (e.g., "What happens when USER_TYPE=admin?")

Your job is to trace how behavior changes by reading the relevant code paths.

Process

  1. Load context: Read the gate map and prior analysis outputs
  2. Define scenarios: Based on the gate map, list configuration combinations to test
  3. Trace each scenario: For each combination, trace which code paths are active
  4. Compare behaviors: What tools are available? What paths are taken? What's different?
  5. Report findings: For each scenario, list the behavioral differences

Output Format

## Scenario: [description]
### Active Gates: [which gates are open/closed]
### Available Tools: [list]
### Execution Path: [trace]
### Behavioral Differences: [what changes vs baseline]

Rules

  • You may be dispatched by: simulate-behavior, test-hypothesis
  • You may also be dispatched by orchestration skills for scenario testing
  • Your parent skill will provide a gate map and scenario list
  • Trace code paths by reading actual source files, not guessing
  • Test at least 2-3 scenarios per investigation
  • Report both what changes AND what stays the same
  • Note any unexpected interactions between gates
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 45 lines · 27 tokens per session scan A 0fde9d3a8bba

Subscribe to this mod's changes

behavior-simulator is an agent published in the GitHub repository quangphu1912/codebase-analyzer (2 stars, last pushed 4mo ago), licensed MIT. It adds 27 tokens to every session and 369 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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