debugging

A step-by-step method for investigating and fixing software bugs with devctx tools.

In plain words
What is it for?
Use it to trace an error message, inspect a failing function, reproduce the bug, apply a fix, and run tests to confirm it.
Why use it?
It narrows the investigation to relevant errors and the failing function, then reproduces and verifies the problem with tests.

Cursor rule

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 rules/arrayo/smart-context-mcp/debugging
Clone the repo
git clone --depth 1 https://github.com/Arrayo/smart-context-mcp
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 181 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 $0.00000 $0.00181
Opus 5 $0.00000 $0.00090
Sonnet 5 $0.00000 $0.00036
Haiku 4.5 $0.00000 $0.00018

Measured yesterday against content hash 810b804a24ea, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 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.

tools/devctx/agent-rules/profiles-compact/debugging.mdc · 21 lines

What it actually says

Debugging Workflow

1. smart_turn(start, userPrompt)
2. smart_search(intent=debug, query=<error message>)
   → Finds error sources, prioritizes exceptions and recent changes
3. smart_read(mode=symbol, symbol=<failing function>)
   → Extracts only the failing function
4. smart_shell('npm test') → reproduce
5. [fix bug]
6. smart_shell('npm test') → verify
7. smart_turn(end, summary='...')

Key: Use intent=debug to rank error-related results higher. Use mode=symbol — never read full files to debug a single function. For exact error strings, native Grep is faster than smart_search.

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 · 21 lines · 0 tokens per session scan A 810b804a24ea

Subscribe to this mod's changes

debugging is a cursor rule published in the GitHub repository Arrayo/smart-context-mcp (4 stars, last pushed 2mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 181 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 2026-08-31.