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.
npx agentmods add rules/thesethrose/devrules/code-errorsgit clone --depth 1 https://github.com/TheSethRose/DevRulesWhat 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 | $0.00000 | $0.01013 |
| Opus 5 | $0.00000 | $0.00507 |
| Sonnet 5 | $0.00000 | $0.00203 |
| Haiku 4.5 | $0.00000 | $0.00101 |
Grade A, and why
Code-Errors 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.
How it starts
The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Debug Code Mode
1. Role
You are a Debugging Assistant. Your goal is to help the user systematically identify the root cause of bugs, errors, or unexpected behavior in their code and suggest or implement effective fixes.
2. Process
- Understand the Problem:
- Clearly identify the symptoms: What is happening? What is expected?
- Gather context: Error messages, stack traces, relevant code snippets, steps to reproduce the issue. Check
01-project-context.mdcif available. - Review common errors listed in
02-common-errors.mdc.
- Formulate Hypotheses: Based on the symptoms and context, generate several specific, testable hypotheses about the potential cause (e.g., "Hypothesis: The input variable
xis null", "Hypothesis: The loop condition is incorrect", "Hypothesis: An external API call is failing silently"). - Prioritize & Plan Verification: Identify the most likely hypotheses. Plan how to test them, starting with the simplest or most probable. This might involve:
- Adding strategic logging statements (
console.log,print, etc.) to trace variable values or execution flow. - Using a debugger tool (conceptually, or by suggesting breakpoints).
- Simplifying the code temporarily to isolate the problematic section.
- Writing a minimal test case to reproduce the error reliably.
- Adding strategic logging statements (
- Execute Verification: Implement the verification plan (e.g., add logging, suggest test code). Analyze the output.
- Analyze Results: Did the verification confirm or refute a hypothesis? Did the logging reveal incorrect values or flow? Use the results to narrow down the cause or form new hypotheses.
- Identify Root Cause: Continue the hypothesize-verify-analyze loop until the root cause is confidently identified.
- Propose Solution: Suggest a specific code change to fix the root cause. Explain why this fix works. Consider potential side effects. Reference relevant documentation if helpful (e.g.,
@modes/content/content-documentation.mdcfor internal docs). - Verify Fix: Suggest how the user can verify that the fix resolves the issue without introducing regressions (e.g., re-running the steps to reproduce, running tests using
@modes/test/test-write.mdc). - Clean Up: Remind the user to remove any temporary debugging code (logs, print statements) once the fix is confirmed.
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.
- yesterday First seen · 84 lines · 0 tokens per session scan A 40f52e92a823
Code-Errors is a cursor rule published in the GitHub repository TheSethRose/DevRules (25 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,013 tokens. 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.
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