retro

retro is a skill for Claude Code from jasonm4130/claude-skills. It costs 128 tokens per session (2,076 once invoked), scanned A, original, MIT.

An interactive review of a completed coding session that examines what happened, what changed, and which moments were important. It records useful lessons for future work.

In plain words
What is it for?
Use it at the end of a work session to review changes, investigate key decisions, and save structured notes about the work.
Why use it?
It turns a finished session into specific, reusable knowledge instead of letting decisions and discoveries disappear.

Skill for Claude Code

Written for Claude Code: ${CLAUDE_PLUGIN_DATA} variable. Also seen: mentions Codex.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the session-retro plugin — 1 skill shipped together

Good fit Use it at the end of a work session to review changes, investigate key decisions, and save structured notes about the work.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add jasonm4130/claude-skills
Claude Code
/plugin install session-retro

Made for: Claude Code.

Or install session-retro, the plugin that ships this one along with the rest of its 1 skill.

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 retro

README.md
[![agentmods](https://agentmods.dev/badge/skills/jasonm4130/claude-skills/retro/github.svg)](https://agentmods.dev/skills/jasonm4130/claude-skills/retro)
Your own site
<a href="https://agentmods.dev/skills/jasonm4130/claude-skills/retro"><img src="https://agentmods.dev/badge/skills/jasonm4130/claude-skills/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 retro

Your own site · 80×15
<a href="https://agentmods.dev/skills/jasonm4130/claude-skills/retro"><img src="https://agentmods.dev/badge/skills/jasonm4130/claude-skills/retro.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 128 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,076 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 $0.00128 $0.02076
Opus 5 $0.00064 $0.01038
Sonnet 5 $0.00026 $0.00415
Haiku 4.5 $0.00013 $0.00208

Measured 11d ago against content hash 71dfcf3be766, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

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 11d 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.

plugins/session-retro/skills/retro/SKILL.md · 213 lines

How it starts

The opening of the file, as written. The whole thing — 213 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Session Retrospective

You are running an interactive session retrospective. Your goal is to walk through this session with the user, understand what happened and why, and write structured memory entries useful in future sessions.

The retro is batch-scoped: it retrospects every unprocessed worthy session (the sessions in retro-worthy.jsonl not yet in retro-processed.jsonl) plus the current session, not just the current one — because the end-of-day offer arrives at most once a day, by which point several worthy sessions may have accrued, and each deserves capture. It reads two cheap signals: the per-session JSONL event logs (append-only, maintained by the PostToolUse hook) and live git state for the current tree (git status, git diff --stat, git log since session start). It does NOT parse the raw session JSONL transcript and does NOT depend on claude-mem.

Step 1: Collect the batch + quick-skip gate

Run the collector once. It resolves the batch, aggregates each session's event log, prints the snapshot, and persists it to retro-batch-{sid}.json for Steps 2 and 6 to reuse — do not run it again in later steps.

CLAUDE_PLUGIN_DATA="${CLAUDE_PLUGIN_DATA}" node "${CLAUDE_PLUGIN_ROOT}/scripts/collect-batch-sessions.mjs" "${CLAUDE_SESSION_ID}"

The snapshot is { boundaryTs, processedSids, totalSessions, cappedFrom?, batch: [ {sid, isCurrent, startDate, edits, writes, bashCalls, filesTouched, reasons, firstTs, lastTs} ] }. Decide on the whole batch: if no session in batch has any edits or writes, offer to skip.

  • If the user declines a skip / there is signal → continue to Step 2.
  • If the user accepts the skip (nothing to capture) → still run Step 6 cleanup. A skip is a disposition: marking the batch processed stops a zero-signal batch (e.g. one whose event logs are missing) from re-triggering the nudge forever.

If cappedFrom is set, tell the user only the most-recent sessions are shown and the rest remain queued for a later retro.

Read the full file on GitHub · 213 lines

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. 11d ago First seen · 213 lines · 128 tokens per session scan A 71dfcf3be766

Subscribe to this mod's changes

retro is a skill published in the GitHub repository jasonm4130/claude-skills (5 stars, last pushed 4d ago), licensed MIT. It adds 128 tokens to every session and 2,076 once invoked, about $0.0006 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.

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