dx-lesson

dx-lesson is a skill for Claude Code, Codex from dikamilo/dx-workflow. It costs 29 tokens per session (589 once invoked), scanned A, original, MIT.

An append-only record for an important warning or a decision and the reason behind it. It stores these findings in foundation/lessons.md so future work can refer to them.

In plain words
What is it for?
Recording what caused a problem, why a design choice was made, or why a tempting refactor should not be done.
Why use it?
It prevents the team from repeating the same mistakes or reconsidering decisions without their original context.

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/dikamilo/dx-workflow/dx-lesson
Any agent
npx skills add dikamilo/dx-workflow --skill dx-lesson
Clone the repo
git clone --depth 1 https://github.com/dikamilo/dx-workflow

Made for: Claude Code, Codex.

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 dx-lesson

README.md
[![agentmods](https://agentmods.dev/badge/skills/dikamilo/dx-workflow/dx-lesson.svg)](https://agentmods.dev/skills/dikamilo/dx-workflow/dx-lesson)
Your own site
<a href="https://agentmods.dev/skills/dikamilo/dx-workflow/dx-lesson"><img src="https://agentmods.dev/badge/skills/dikamilo/dx-workflow/dx-lesson.svg" alt="Measured on agentmods" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 589 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 $0.00029 $0.00589
Opus 5 $0.00015 $0.00295
Sonnet 5 $0.00006 $0.00118
Haiku 4.5 $0.00003 $0.00059

Measured today against content hash 2d7876cd5e40, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

dx-lesson 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 today.

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/dx-lesson/SKILL.md · 46 lines

How it starts

The opening of the file, as written. The whole thing — 46 lines — stays where its author put it; the contents beside it link to each section on GitHub.

dx-lesson

Capture one finding so a future change re-reads it instead of relitigating it. A lesson is scar tissue or a load-bearing decision — a rule, not a story. Two flavors, both belong here: cautionary ("this broke because…") and decisional ("we chose X over Y because Z", including a rejected refactor: "don't re-deepen X — it's shallow on purpose because Y"). This is the anteroom to a standard, not an ADR — the framework has no separate decision register.

Guard. foundation/lessons.md must exist (it does after /dx-init). If it is missing, tell the user to run /dx-init first. Read foundation/glossary.md for naming — a one-line habit, no section.

1 — Get the finding

Take the finding from the argument. If nothing was passed, ask what broke or what was decided, and why it matters — one question, then proceed. Don't turn a capture into an interview.

2 — Load the entry shape (invoke dx-references with knowledge-layer)

Use it for the lesson entry shape and to judge whether this is a lesson at all (a one-off finding is fine here; a recurring one is a promotion candidate — see step 4).

3 — Append (never rewrite)

Append to the end of foundation/lessons.md. Never edit, reorder, dedupe, or reformat existing entries — the file is append-only; that friction is the point. One entry, this shape:

## <short title> — <YYYY-MM-DD>
<what happened / what was decided>. **Why:** <the reason it matters>. **How to apply:** <the rule going forward>.

Keep it tight — the title is what future skills scan first.

4 — Flag for promotion if it will recur

If the finding looks like it will keep coming up across changes, note it — that is the trigger for graduating it into a standard via /dx-standards-update. Don't promote here; lessons are the append-only home.

Done when

The entry is the last section of foundation/lessons.md and existing entries are untouched. Then print and stop:

Lesson recorded: foundation/lessons.md — ## <short title>
Next: /dx-standards-update   — only if this will recur across changes (promote it to a standard)

Read the full file on GitHub · 46 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. today Changed · -1 lines 2d7876cd5e40
  2. 5d ago First seen · 47 lines · 29 tokens per session scan A 3f2f85ec8ee3

Subscribe to this mod's changes

dx-lesson is a skill published in the GitHub repository dikamilo/dx-workflow (5 stars, last pushed 4d ago), licensed MIT. It adds 29 tokens to every session and 589 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.

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