bug-echo

A post-fix scanner that looks through a codebase for other occurrences of the same bug pattern. It classifies the matches and produces a rated report.

In plain words
What is it for?
Run it after fixing a real bug to search for related code, verify possible matches, and document which findings need attention.
Why use it?
It helps prevent a bug fix from leaving behind similar problems elsewhere, including cases that have not failed yet.

Skill for Claude CodeCodex

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 skills/terryc21/bug-echo/bug-echo
Any agent
npx skills add Terryc21/bug-echo --skill bug-echo
Clone the repo
git clone --depth 1 https://github.com/Terryc21/bug-echo

Made for: Claude Code, Codex.

Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 12,229 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 $0.00069 $0.12229
Opus 5 $0.00034 $0.06115
Sonnet 5 $0.00014 $0.02446
Haiku 4.5 $0.00007 $0.01223

Measured 2d ago against content hash a58b15577931, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

bug-echo 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 2d 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.

skills/bug-echo/SKILL.md · 617 lines

How it starts

The opening of the file, as written. The whole thing — 617 lines — stays where its author put it; the contents beside it link to each section on GitHub.

bug-echo

Quick Ref: After a bug fix, identify the pattern, scan the codebase, classify findings, and produce a rated report. Output: .agents/research/YYYY-MM-DD-bug-echo-<slug>.md.

Best invoked after a real fix

bug-echo is most effective when the pattern came from a fix that just shipped. A real fix proves which anti-pattern matters in your specific codebase. Pattern matching after a real fix is dramatically more accurate than pattern matching from a theoretical catalog — the fix is the evidence the pattern is a bug.

The high-leverage loop is surface → verify → generalize, three skills working in sequence:

  1. Surface/unforget (or any tracker) shows you a deferred row you're about to mark Fixed.
  2. Verify — Before trusting the closure, confirm the fix is real. /radar-suite focus on <symbol> (or just reading the file) catches stale Open rows where the fix shipped weeks ago and nobody updated the ledger.
  3. Generalize — Run /bug-echo with a one-sentence description of what the fix replaced. The output is a rated list of every echo of that anti-pattern across the codebase — including instances that haven't crashed yet but sit under the same runtime conditions.

Bugs that haven't fired yet are the highest-ROI thing in any audit cycle. They cost the same to fix as crashed bugs, but you skip the cost of the crash itself (lost user trust, support tickets, root-cause investigation under deadline). bug-echo is the systematic way to find them.

Companion skills:

  • unforget (https://github.com/Terryc21/unforget) — the surface; consolidates deferred work in one file
  • radar-suite (https://github.com/Terryc21/radar-suite) — the verifier; confirms the fix is real before bug-echo generalizes

bug-echo also runs standalone when you describe the pattern manually (Step 2A below) — useful when no recent fix exists but you've spotted a shape worth chasing.


This is a workflow to run, not a procedure to summarize. The user invoked it because they want the scan performed and the findings in hand; a description of what bug-echo would do leaves them exactly where they started.

Read the full file on GitHub · 617 lines

Files

What ships with it

5 files 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.

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. 2d ago First seen · 617 lines · 69 tokens per session scan A a58b15577931

Subscribe to this mod's changes

bug-echo is a skill published in the GitHub repository Terryc21/bug-echo (23 stars, last pushed 4d ago), licensed Apache-2.0. It adds 69 tokens to every session and 12,229 once invoked, about $0.0003 per session on Opus 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.

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