gbu-retro

gbu-retro is a command for Claude Code from XyndoX/good-bad-ugly. It costs 12 tokens per session (359 once invoked), scanned A, original, MIT.

A post-session review command that records lessons from a coding session as durable project guidance. It looks for incidents, repeated corrections, changed requirements, stalled agents, and checks that failed to catch real problems.

In plain words
What is it for?
Use it after a session to identify workflow failures and update project documentation or general operating rules.
Why use it?
It helps prevent the same process mistakes from recurring in later sessions. The lessons are stored where future work can use them, with the smallest useful documentation change.

Command for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the good-bad-ugly plugin — 1 skill, 4 commands, 2 agents shipped together

Good fit Use it after a session to identify workflow failures and update project documentation or general operating rules.

Compare 6 commands from other repositories ↓
Install with agentmods
npx agentmods add commands/xyndox/good-bad-ugly/gbu-retro
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/XyndoX/good-bad-ugly

Made for: Claude Code.

Or install good-bad-ugly, the plugin that ships this one along with the rest of its 1 skill, 4 commands, 2 agents.

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.

agentmods badge for gbu-retro

README.md
[![agentmods](https://agentmods.dev/badge/commands/xyndox/good-bad-ugly/gbu-retro/github.svg)](https://agentmods.dev/commands/xyndox/good-bad-ugly/gbu-retro)
Your own site
<a href="https://agentmods.dev/commands/xyndox/good-bad-ugly/gbu-retro"><img src="https://agentmods.dev/badge/commands/xyndox/good-bad-ugly/gbu-retro/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.

agentmods 80×15 button for gbu-retro

Your own site · 80×15
<a href="https://agentmods.dev/commands/xyndox/good-bad-ugly/gbu-retro"><img src="https://agentmods.dev/badge/commands/xyndox/good-bad-ugly/gbu-retro.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 12 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 359 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00012 $0.00359
Opus 5 $0.00006 $0.00179
Sonnet 5 $0.00002 $0.00072
Haiku 4.5 $0.00001 $0.00036

Measured 10d ago against content hash f3a4b71d6dd2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

gbu-retro 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 10d 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.

commands/gbu-retro.md · 32 lines

What it actually says

Run a good-bad-ugly retrospective on the current session. The goal is not a summary — it is to harvest anything that should change how future sessions run, and put it where future sessions will actually see it.

  1. Sweep the session for scars. Incidents (data touched that shouldn't have been, money spent unexpectedly, a gate that passed while the product was broken), corrections the user had to make twice, specs that got superseded mid-flight, agents that went quiet, verification that turned out vacuous.

  2. For each scar, ask: which layer failed? A brief missing a fence or a fixture rule → the prompt template needs the rule. A verification gap → the verify step needs the check. A user-facing surprise → the loop needs a communication step. If it couldn't have been prevented by better doctrine, say so — not everything is a process failure.

  3. Write the durable artifact, smallest first:

    • a one-line addition to an existing pitfalls/rules list beats a new section;
    • a new section beats a new file;
    • a new file needs to earn its keep. Update the project's own docs/memory for project-specific lessons; update this plugin's SKILL.md/docs for workflow-general ones. Real cases beat abstract rules — cite what actually happened, anonymized to its mechanism.
  4. Report to the user: what was harvested, where it landed, and the one lesson most worth remembering. Skip ceremony if the session was clean — "no doctrine-worthy scars" is a valid outcome.

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. 10d ago First seen · 32 lines · 12 tokens per session scan A f3a4b71d6dd2

Subscribe to this mod's changes

gbu-retro is a command published in the GitHub repository XyndoX/good-bad-ugly (1 stars, last pushed 1mo ago), licensed MIT. It adds 12 tokens to every session and 359 once invoked, about $0.0001 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 2026-08-31.