A debugging procedure that starts by exploring relevant files, collecting errors and other evidence, then testing several possible root causes. It also lists optional tools for browser, database, and library investigations.

Use it to investigate application errors, frontend problems, database issues, library or API problems, and performance concerns.

It reduces guesswork by requiring context and evidence before changing code.

debugging — Cursor rule for Cursor by rm2thaddeus/Pixel

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/rm2thaddeus/Pixel_Detective

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/rm2thaddeus/pixel_detective/debugging/github.svg)](https://agentmods.dev/rules/rm2thaddeus/pixel_detective/debugging)

Your own site

<a href="https://agentmods.dev/rules/rm2thaddeus/pixel_detective/debugging"><img src="https://agentmods.dev/badge/rules/rm2thaddeus/pixel_detective/debugging/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/rm2thaddeus/pixel_detective/debugging"><img src="https://agentmods.dev/badge/rules/rm2thaddeus/pixel_detective/debugging.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 3 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 860 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	$0.00003	$0.00860
Opus 5.5	$0.00001	$0.00344
Sonnet 5.5	$0.00001	$0.00172
Haiku 4.5	$0.00000	$0.00086

Measured 1mo ago against content hash ab76e4d73921, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

debugging 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 1mo 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.

.cursor/rules/debugging.mdc · 78 lines

How it starts

The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Before starting to debug, take your time to explore the files related with the user request.

Once found, use appropriate MCP servers to gather relevant context and debug information:

MCP-Enhanced Debugging Workflow

1. Collect Context & Evidence

Error Analysis: Capture error messages, logs, stack traces
File Discovery: Use grep_search for exact matches, codebase_search for broader context
Frontend Issues:
- Use Browser Tools MCP to capture console logs (mcp_browser-tools_getConsoleLogs, mcp_browser-tools_getConsoleErrors)
- Capture network errors (mcp_browser-tools_getNetworkErrors)
- Take screenshots (mcp_browser-tools_takeScreenshot) for visual issues
Database Issues: Use Supabase MCP to query data and check schema integrity
Library/API Issues: Use Context7 MCP to gather relevant documentation

2. Investigate Root Causes

List ≥3 hypotheses based on collected evidence
Confirm via targeted file reading (cat -n) & project structure (tree)
Frontend Root Causes: Run comprehensive audits (mcp_browser-tools_runAuditMode)
Performance Issues: Use mcp_browser-tools_runPerformanceAudit
Database Root Causes: Execute diagnostic SQL queries via Supabase MCP

3. Reuse Patterns & Solutions

Search for prior fixes or utilities in codebase
Library Documentation: Use Context7 MCP for up-to-date API examples and troubleshooting guides
Similar Issues: Use GitHub MCP to search for related issues in project history

4. Analyze Impact & Dependencies

Trace dependencies and side-effects
Frontend Impact: Use Browser Control MCP to analyze affected pages/components
Database Impact: Check foreign key constraints and data integrity via Supabase MCP
Cross-System Impact: Consider how changes affect multiple MCP domains

5. Propose & Implement Fixes

Specify file paths, line numbers, code snippets with clear justification
Clean Debugging Environment: Use mcp_browser-tools_wipeLogs before testing fixes
Database Fixes: Use transactions in Supabase MCP for safe schema/data changes
Code Changes: Use GitHub MCP for version-controlled implementation

Read the full file on GitHub · 78 lines

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.

1mo ago First seen · 78 lines · 3 tokens per session scan A ab76e4d73921

Subscribe to this mod's changes

debugging is a cursor rule published in the GitHub repository rm2thaddeus/Pixel_Detective (21 stars, last pushed 8mo ago), licensed MIT. It adds 3 tokens to every session and 860 once invoked, about $0.0000 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 2026-08-30.

Debugging

error-handling-and-validation

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

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debugging