reproduction-trace-instrumenter

reproduction-trace-instrumenter is a skill for Claude Code, Codex from ArabelaTso/Skills-4-SE. It costs 103 tokens per session (2,078 once invoked), scanned A, original, Apache-2.0.

A code-instrumentation tool that records what a program does while reproducing a reported bug, including calls, values, control flow, and program state. It can also create scripts for replaying the failure.

In plain words
What is it for?
Use it to capture a failing run, preserve the inputs and code path involved, and replay the behavior for diagnosis.
Why use it?
It makes a bug's execution easier to inspect and repeat when ordinary logs or manual reproduction do not show enough detail.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to capture a failing run, preserve the inputs and code path involved, and replay the behavior for diagnosis.

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Install with agentmods
npx agentmods add skills/arabelatso/skills-4-se/reproduction-trace-instrumenter
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.

Any agent
npx skills add ArabelaTso/Skills-4-SE --skill reproduction-trace-instrumenter
Clone the repo
git clone --depth 1 https://github.com/ArabelaTso/Skills-4-SE

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for reproduction-trace-instrumenter

README.md
[![agentmods](https://agentmods.dev/badge/skills/arabelatso/skills-4-se/reproduction-trace-instrumenter/github.svg)](https://agentmods.dev/skills/arabelatso/skills-4-se/reproduction-trace-instrumenter)
Your own site
<a href="https://agentmods.dev/skills/arabelatso/skills-4-se/reproduction-trace-instrumenter"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/reproduction-trace-instrumenter/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for reproduction-trace-instrumenter

Your own site · 80×15
<a href="https://agentmods.dev/skills/arabelatso/skills-4-se/reproduction-trace-instrumenter"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/reproduction-trace-instrumenter.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 103 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,078 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00103 $0.02078
Opus 5 $0.00051 $0.01039
Sonnet 5 $0.00021 $0.00416
Haiku 4.5 $0.00010 $0.00208

Measured 9d ago against content hash 6edd918842f4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

reproduction-trace-instrumenter 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 9d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/python_instrumenter.py, scripts/replay_generator.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/reproduction-trace-instrumenter/SKILL.md · 322 lines

How it starts

The opening of the file, as written. The whole thing — 322 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Reproduction Trace Instrumenter

Overview

This skill instruments source code to capture detailed execution traces for bug reproduction. It records function calls, variable values, control flow, and program state, then generates replay scripts to deterministically reproduce the bug for diagnosis.

Workflow

1. Identify the Bug Context

Before instrumentation, understand:

  • What is the bug or failure being investigated?
  • Which code paths are likely involved?
  • What inputs trigger the bug?
  • Is the bug deterministic or intermittent?

2. Instrument the Code

Use the appropriate instrumenter for your language:

Python Instrumentation
python scripts/python_instrumenter.py <source_file.py> -o <instrumented_file.py>

Options:

  • --no-functions: Disable function call tracing
  • --no-variables: Disable variable assignment tracing
  • --no-control-flow: Disable control flow tracing
  • --exclude <patterns>: Exclude functions matching patterns (e.g., __init__ test_*)

Example:

# Full instrumentation
python scripts/python_instrumenter.py app.py -o app_instrumented.py

# Minimal instrumentation (functions only)
python scripts/python_instrumenter.py app.py -o app_instrumented.py --no-variables --no-control-flow

# Exclude test functions
python scripts/python_instrumenter.py app.py -o app_instrumented.py --exclude test_ __

3. Run the Instrumented Code

Execute the instrumented program with the inputs that trigger the bug:

python app_instrumented.py

The execution trace will be automatically saved to trace.json when the program exits.

Trace Output:

  • trace.json: Complete execution trace with all recorded events
  • Console output: Summary of trace recording

4. Analyze the Trace

Generate a human-readable summary:

python scripts/replay_generator.py trace.json --summary

This shows:

  • Total number of events
  • Event type distribution
  • Function call sequence
  • Maximum call depth

5. Generate Replay Script

Read the full file on GitHub · 322 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 322 lines · 103 tokens per session scan A 6edd918842f4

Subscribe to this mod's changes

reproduction-trace-instrumenter is a skill published in the GitHub repository ArabelaTso/Skills-4-SE (252 stars, last pushed 22d ago), licensed Apache-2.0. It adds 103 tokens to every session and 2,078 once invoked, about $0.0005 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 2026-09-03.

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