Borrowing it
Nothing to install: this file belongs to stainless-code/codemap. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/stainless-code/codemap/main/.agents/skills/diagnosing-bugs/SKILL.mdgit clone --depth 1 https://github.com/stainless-code/codemapWrote 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.
[](https://agentmods.dev/skills/stainless-code/codemap/diagnosing-bugs)<a href="https://agentmods.dev/skills/stainless-code/codemap/diagnosing-bugs"><img src="https://agentmods.dev/badge/skills/stainless-code/codemap/diagnosing-bugs/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.
<a href="https://agentmods.dev/skills/stainless-code/codemap/diagnosing-bugs"><img src="https://agentmods.dev/badge/skills/stainless-code/codemap/diagnosing-bugs.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00068 | $0.02457 |
| Opus 5.5 | $0.00027 | $0.00983 |
| Sonnet 5.5 | $0.00014 | $0.00491 |
| Haiku 4.5 | $0.00007 | $0.00246 |
Grade A, and why
diagnosing-bugs 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.
How it starts
The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Diagnosing bugs
A discipline for hard bugs. Skip phases only when explicitly justified.
When exploring the codebase, query codemap (the structural SQLite index) before reaching for Grep or Read per the codemap rule — symbol-shaped questions ("where is X defined?", "what calls X?") have direct answers in the symbols / calls tables. Read the relevant section of docs/architecture.md to ground the mental model of layering, and check docs/glossary.md for canonical domain terms (file types, recipe ids, schema columns).
Phase 1 — Build a feedback loop
This is the skill. Everything else is mechanical. If you have a fast, deterministic, agent-runnable pass/fail signal for the bug, you will find the cause — bisection, hypothesis-testing, and instrumentation all just consume that signal. If you don't have one, no amount of staring at code will save you.
Spend disproportionate effort here. Be aggressive. Be creative. Refuse to give up.
Ways to construct one — try them in roughly this order
- Failing test at whatever seam reaches the bug — unit, integration, e2e. Codemap convention:
src/**/<name>.test.tsfor unit + integration;fixtures/golden/for query-shape regressions;bun test <file>runs them. - CLI invocation with a fixture input, diffing stdout against a known-good snapshot. Examples:
bun src/index.ts query --json …againstfixtures/minimal/, golden runner underscripts/query-golden.ts. - Replay a captured trace. Save a real
.codemap/index.db/ config / fixture file to disk; replay it through the code path in isolation. - Throwaway harness. Spin up a minimal subset (one parser, one DB connection) that exercises the bug code path with a single function call.
- Property / fuzz loop. If the bug is "sometimes wrong output", run 1000 random inputs and look for the failure mode.
- Bisection harness. If the bug appeared between two known states (commit, dataset, version), automate "boot at state X, check, repeat" so you can
git bisect runit. - Differential loop. Run the same input through old-version vs new-version (or two configs) and diff outputs. The B.6 baseline machinery (
codemap query --save-baseline/--baseline) is built for exactly this — use it. - HITL bash script. Last resort. If a human must click or copy a value out of the IDE, drive them with
scripts/hitl-loop.template.shso the loop is still structured. Captured output feeds back to you.
What ships with it
1 file 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.
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 · 142 lines · 68 tokens per session scan A a70800faa2c0
diagnosing-bugs is a skill published in the GitHub repository stainless-code/codemap (8 stars, last pushed yesterday), licensed MIT. It adds 68 tokens to every session and 2,457 once invoked, about $0.0003 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.
Other skills, from other repositories
roam
Codebase comprehension via roam-code CLI. Use when exploring codebases, planning modifications, debugging failures, assessing PR risk, or checking architecture health. Triggers on: understanding project structure, pre-change safety checks, finding symbols/files, blast radius analysis, affected tests, health scoring…
enola
Use Enola when investigating architecture, dependencies, blast radius, cross-repository relationships, structural regressions, or what a code change did to the system.
agentmap
Use for TypeScript/JavaScript codebase navigation — symbol lookup, blast radius, reuse checks, and repo orientation. Prefer agentmap before serial grep when exploring imports, exports, or where a symbol lives. Package is @raymondchins/agentmap (not the unrelated npm package agentmap).
m1nd-first
Use when investigating a repository, searching for implementation, reviewing changes, working from specs/docs, or preparing a risky code change in an environment where m1nd is available. This doctrine makes m1nd the first investigative layer before grep, glob, or manual file reads, except when the task is pure…
sipcode-regress
Check the user's own local Claude Code and Codex logs for regressions after an update (prompt-cache misses, 5-minute cache TTL, uncached context, hourly cache rebuilds, Codex usage limit draining faster per token) and pin each one to the version that introduced it, using the Sipcode CLI. Use when the user asks whether…
ctxo-safe-edit
Use BEFORE editing, renaming, or deleting any function, class, or method, to avoid breaking dependents.