session-retro

session-retro is a skill for Claude Code from momentmaker/kaijutsu. It costs 81 tokens per session (1,091 once invoked), scanned A, original, MIT.

A retrospective that reviews a coding session for useful lessons, recurring patterns, mistakes, fixes, and user preferences.

In plain words
What is it for?
It examines the conversation and recent retrospectives, then surfaces errors, repeated workflows, corrections, codebase facts, and possible improvements to save for later.
Why use it?
It turns one session’s discoveries into actionable knowledge and can reveal problems that keep appearing across earlier sessions.

Skill for Claude Code

Written for Claude Code: PostToolUse hook event. Also seen: mentions subagents.

Good fit It examines the conversation and recent retrospectives, then surfaces errors, repeated workflows, corrections, codebase facts, and possible improvements to save for later.

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Install with agentmods
npx agentmods add skills/momentmaker/kaijutsu/session-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.

Any agent
npx skills add momentmaker/kaijutsu --skill session-retro
Clone the repo
git clone --depth 1 https://github.com/momentmaker/kaijutsu

Made for: Claude Code.

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 session-retro

README.md
[![agentmods](https://agentmods.dev/badge/skills/momentmaker/kaijutsu/session-retro.svg)](https://agentmods.dev/skills/momentmaker/kaijutsu/session-retro)
Your own site
<a href="https://agentmods.dev/skills/momentmaker/kaijutsu/session-retro"><img src="https://agentmods.dev/badge/skills/momentmaker/kaijutsu/session-retro.svg" alt="Measured on agentmods" height="20"></a>
Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,091 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 $0.00081 $0.01091
Opus 5 $0.00041 $0.00545
Sonnet 5 $0.00016 $0.00218
Haiku 4.5 $0.00008 $0.00109

Measured 7d ago against content hash 6bc0612bfb7e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

session-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 7d 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/community/session-retro/SKILL.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Session Retrospective

Review the current conversation to surface actionable learnings, then help the user decide what to persist.

Step 0: Cross-session pattern check

Before scanning the current conversation alone, look at the last 3-5 retros (if any) in .claude/retros/ or in project-memory. If a pattern is repeating across multiple sessions — same friction, same kind of error, same skill gap — surface it specifically. Cross-session patterns are higher-signal than one-off observations.

Step 1: Scan the Conversation

Read through the full conversation and extract items in these categories:

Errors & Fixes

  • What broke and how it was fixed
  • Root causes that were non-obvious
  • Workarounds that succeeded after initial approaches failed

Repeated Patterns

  • Sequences of tool calls or steps that appeared 3+ times
  • Copy-pasted prompts or instructions given to subagents
  • Manual processes that could be automated

User Corrections

  • Times the user redirected your approach
  • Explicit preferences stated ("always do X", "never do Y", "I prefer Z")
  • Implicit preferences revealed by approvals/rejections

Knowledge Gained

  • Codebase facts discovered (file locations, conventions, gotchas)
  • External system behaviors learned (API quirks, tool limitations)
  • Configuration or environment details that affected the work

Workflow Friction

  • Steps that took multiple attempts
  • Places where context was lost or repeated
  • Tasks that would benefit from a hook, skill, or MCP server

Step 2: Present Findings

Group findings into a concise table:

## Session Retrospective

### Potential Memory Entries (persist across sessions)
| # | Finding | Type | Source |
|---|---------|------|--------|
| 1 | R2 bucket uploads need --content-type flag | codebase fact | error at turn 12 |
| 2 | User prefers max 10 concurrent agents | preference | explicit instruction |

### Potential Skill Opportunities (automate repeated work)
| # | Pattern | Frequency | Effort |
|---|---------|-----------|--------|
| 1 | Batch sentence generation with 10-agent concurrency | 5 times | medium |

### Potential Skill Improvements (existing skills that fell short)
| # | Skill | Issue | Suggestion |
|---|-------|-------|------------|
| 1 | generate-japanese | No furigana validation step | Add post-gen validation |

### Potential Hooks / Automation
| # | Trigger | Action | Why |
|---|---------|--------|-----|
| 1 | PostToolUse:Write on *.json | Validate JSON schema | Caught 3 malformed files |

Read the full file on GitHub · 100 lines

Files

What ships with it

2 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. 7d ago First seen · 100 lines · 81 tokens per session scan A 6bc0612bfb7e

Subscribe to this mod's changes

session-retro is a skill published in the GitHub repository momentmaker/kaijutsu (3 stars, last pushed 2mo ago), licensed MIT. It adds 81 tokens to every session and 1,091 once invoked, about $0.0004 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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