What it does
retro reviews an agent session the way a team reviews a sprint: not what happened, but what made the work slower than it needed to be — and what change stops it happening again. You were there, so it never summarizes; the deliverable is friction with fixes.
Every finding must carry a receipt — a specific moment in the thread it can point to. Generic best practice with no receipt is not a finding, which is what keeps the output short and worth acting on.
When to reach for it
- Invocation mode. You invoke this by typing
/retro— the agent won’t reach for it on its own. - Trigger boundary. Reach for it at the end of a session that felt slower than it should have, or point it at a past session. It reviews workflow, not code — to review the code itself, use a code-review skill.
The fix ladder
For each finding, the skill climbs a ladder from cheapest-and-most-durable to weakest: make the mistake impossible in code or tooling, automate it with a committed script, write a line into the repo’s agent instructions, add a skill, or — last — prompt differently next time. It stops at the first rung that actually prevents recurrence, because a rule the agent can ignore is a bad trade against a type error it can’t.
Fixes are portable by default — they work the same whether the next session runs in Claude Code, Codex, Cursor, or none of them. Two homes qualify: checked into the repo, or a globally installed personal skill for a preference that holds across repos. Harness-local config gets labelled as such when proposed, and a Claude memory file is the last resort of all: invisible to every other harness, so it’s only offered with the reason each portable option was ruled out.
It ends by offering to apply the accepted fixes on the spot — editing the instructions file, committing the script, adding the skill — so the retro produces a change, not a document.
It’s working if
- Every finding quotes or cites a specific moment from the session.
- Findings are ranked by recurrence × cost, and there are 3–6 of them — or one, with “clean session” as the verdict.
- Fixes are paste-ready blocks, and you’re asked which to apply.
Where it fits
retro is periodic maintenance — run it every few sessions, or whenever one drags. It sits outside the flows and improves how all of them run. For the map of the whole set, see ask-eddy.