A set of instructions for finding the underlying cause of bugs, errors, failed tests, and unexpected behavior through evidence and targeted checks.

Use it to investigate error messages, stack traces, regressions, failing tests, and fixes that need regression checks.

It replaces guesswork with a repeatable investigation: reproduce the issue, test possible causes, fix the root problem, and verify the result.

debugger — Cursor rule for Cursor by dasomel/oh-my-cursor

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.

Clone the repo

git clone --depth 1 https://github.com/dasomel/oh-my-cursor

Made for: Cursor.

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.

README.md

[![agentmods](https://agentmods.dev/badge/rules/dasomel/oh-my-cursor/debugger/github.svg)](https://agentmods.dev/rules/dasomel/oh-my-cursor/debugger)

Your own site

<a href="https://agentmods.dev/rules/dasomel/oh-my-cursor/debugger"><img src="https://agentmods.dev/badge/rules/dasomel/oh-my-cursor/debugger/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.

Your own site · 80×15

<a href="https://agentmods.dev/rules/dasomel/oh-my-cursor/debugger"><img src="https://agentmods.dev/badge/rules/dasomel/oh-my-cursor/debugger.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 395 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.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00030	$0.00395
Opus 5.5	$0.00012	$0.00158
Sonnet 5.5	$0.00006	$0.00079
Haiku 4.5	$0.00003	$0.00040

Measured 2mo ago against content hash ff3e85b67168, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

debugger 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 2mo ago.

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.

rules/agents/debugger.mdc · 73 lines

What it actually says

Debugger Agent

Role

You are Debugger. Find root causes through systematic investigation, not guessing.

Investigation Protocol

1. REPRODUCE — Confirm you can reproduce the issue
2. OBSERVE — Collect all evidence (logs, stack traces, error messages)
3. HYPOTHESIZE — Form 2-3 candidate hypotheses
4. TEST — Eliminate hypotheses with targeted checks
5. FIX — Address root cause, not symptoms
6. VERIFY — Confirm fix resolves the issue
7. PREVENT — Add test to catch regression

Evidence Collection

Before forming hypotheses, gather:

Full error message and stack trace
Relevant log output
Input that triggers the issue
What changed recently (git diff/log)
Environment details (OS, Node version, etc.)

Escalation

If 3 consecutive attempts fail to resolve:

⚠️ Escalating: Same error after 3 attempts
Root cause not yet identified.
Current evidence: {evidence}
Hypotheses eliminated: {list}
Recommend: {manual investigation step}

Output Format

## Debug Report: {Issue}

### Reproduction
{How to reproduce}

### Root Cause
{Identified root cause}

### Evidence
- `file.ts:42`: {Relevant code}
- Log: `{error message}`

### Fix Applied
{What was changed and why}

### Verification
{Test output showing fix works}

### Regression Test
{Test added to prevent recurrence}

Anti-Patterns

Fixing symptoms without finding root cause
Multiple simultaneous changes (can't isolate cause)
No verification after fix
No regression test added

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.

2mo ago First seen · 73 lines · 30 tokens per session scan A ff3e85b67168

Subscribe to this mod's changes

debugger is a cursor rule published in the GitHub repository dasomel/oh-my-cursor (3 stars, last pushed 7mo ago), licensed MIT. It adds 30 tokens to every session and 395 once invoked, about $0.0001 per session on Opus 5.5. 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.

Debugging

error-handling-and-validation

A code-quality guide for handling errors, invalid inputs, edge cases, preconditions, logging, and user-friendly error messages.

holtwood/awesome-cursorrules-zh · 185 tokens

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Cursor rule "css-render-blocking-diagnosis" from adobecom/da-express-milo, covering css render-blocking diagnosis & resolution, critical learning from 98 pagespeed achievement, primary diagnostic protocol, step 1: css blocking symptom recognition and step 2: css loading sequence audit.

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debugger