retrospective

retrospective is a skill for Claude Code, Codex from ariaxhan/kernel-claude. It costs 65 tokens per session (2,941 once invoked), scanned A, original, MIT.

A process for reviewing lessons from past coding sessions and turning recurring, conflicting, or outdated patterns into improved project guidance.

In plain words
What is it for?
Grouping learnings, resolving contradictions, identifying stale entries, and promoting reliable patterns into skills, agents, or automation hooks.
Why use it?
It helps preserve useful experience without keeping duplicate or stale advice. It also protects frequently used or actively referenced lessons from being archived incorrectly.

Skill for Claude CodeCodex

Part of the kernel plugin — 28 skills, 13 agents, 4 hooks shipped together

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/ariaxhan/kernel-claude/retrospective
Any agent
npx skills add ariaxhan/kernel-claude --skill retrospective
Clone the repo
git clone --depth 1 https://github.com/ariaxhan/kernel-claude

Made for: Claude Code, Codex.

Or install kernel, the plugin that ships this one along with the rest of its 28 skills, 13 agents, 4 hooks.

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 retrospective

README.md
[![agentmods](https://agentmods.dev/badge/skills/ariaxhan/kernel-claude/retrospective.svg)](https://agentmods.dev/skills/ariaxhan/kernel-claude/retrospective)
Your own site
<a href="https://agentmods.dev/skills/ariaxhan/kernel-claude/retrospective"><img src="https://agentmods.dev/badge/skills/ariaxhan/kernel-claude/retrospective.svg" alt="Measured on agentmods" height="20"></a>
Per session 65 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,941 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 5.1 $0.00065 $0.02941
Opus 5 $0.00032 $0.01470
Sonnet 5 $0.00013 $0.00588
Haiku 4.5 $0.00006 $0.00294

Measured yesterday against content hash 876ab34dd5d4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

retrospective 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 yesterday.

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/retrospective/SKILL.md · 223 lines

How it starts

The opening of the file, as written. The whole thing — 223 lines — stays where its author put it; the contents beside it link to each section on GitHub.

A follow-through audit of every retrospective, chronicle, plan and report in the Vaults counted 24 promised fixes: 15 live, 9 dead or never built. The worst mistake class, unverified claims reaching a human, had been written up 11 separate times, and both of its proposed fixes were still unbuilt. Meanwhile improvement-gate.sh, the hook that enforced "every run improves the system that does the work", was retired 2026-07-28 and nothing ever replaced it.

The old version of this skill was not badly reasoned. Its nine lenses were sharp. It failed for one structural reason: every output was a ledger row, and a ledger row enforces nothing. A lesson written to a ledger that nothing reads at the moment of action is a gravestone with better formatting.

So version 3 inverts what this skill is for.

v2 v3
primary question what did we learn did the last learnings actually fire
output ledger rows installed mechanisms, or an explicit accepted-no-mechanism row
when learning happens here, at end of run at error time, by error-loop.py; here only for what error time cannot see
a finding with no mechanism acceptable REFUSED, or recorded as explicitly accepted with a reason

This skill is no longer the primary learning mechanism, and must not be treated as one. Error-time closing belongs to _meta/services/error-loop.py, which opens a defect the moment a gate we own fails and refuses the next commit until a lesson or a waive is recorded. That catches the single instance while the cause is still warm.

What error-time closing structurally CANNOT see is recurrence across runs: the same mistake in different clothes, three independent reinventions of one missing primitive, a guard that has been quietly dead for six weeks. That, and only that, is what this skill is for.

Proportionality is a hard rule, not a preference. Aria has named the failure out loud: "overengineering the fuck out of this". A retrospective longer than the work it describes is a defect. If phase 0 finds nothing dead and phase 2 finds no recurrence, the correct output is four lines saying so.

<on_start> agentdb read-start agentdb recall "<the run's concrete nouns: files, symbols, error text>" for L in beliefs patterns anomalies questions; do tail -20 "_meta/ledgers/$L.jsonl" 2>/dev/null; done python3 _meta/services/error-loop.py list # anything still open from error time? ls -t _meta/reports/retrospective-*.json 2>/dev/null | head -3 </on_start>

A run that adds a new promise while an old one lies dead has made the problem worse, so this phase runs first and cannot be skipped.

  1. Read the previous retrospective's mechanisms[] and the last 20 rows of each ledger.
  2. For each promised mechanism, resolve a verdict. LIVE requires two facts: the file exists AND something invokes it. Prove the second with a grep, never by reading the file.
    • wired into a settings.json hook chain, or
    • a jobctl registry entry that launchctl list actually shows loaded, or
    • a git hook, or
    • a script another live script calls.
  3. Any mechanism whose file exists but which nothing invokes is DEAD, not live. Say so in those words. A file nobody runs is indistinguishable from a file nobody wrote.
  4. Any mechanism that was retired: find its replacement and verify the replacement is LIVE. A retirement with no live successor is a REGRESSION and outranks every new finding this run.
  5. Count: promised, LIVE, DEAD, NEVER BUILT. That ratio is the headline of the report.

OUTPUT: followthrough[], one row per prior mechanism with {name, verdict, invoked_by, evidence}, plus the four counts. A phase 0 with no counts did not run.

Read the full file on GitHub · 223 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. yesterday Changed · +88 lines · +25 tokens per session 876ab34dd5d4
  2. 5d ago First seen · 135 lines · 40 tokens per session scan A dee2761e92b1

Subscribe to this mod's changes

retrospective is a skill published in the GitHub repository ariaxhan/kernel-claude (12 stars, last pushed yesterday), licensed MIT. It adds 65 tokens to every session and 2,941 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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