Retrospective

Capture experiment learnings into a reusable skill registry. The failed attempts table is the most valuable artifact.

Overview

The Retrospective skill captures what was learned during a session — what worked, what failed, exact hyperparameters, and key insights — into a structured registry entry that can be searched and surfaced by future investigations.

This is not for mid-session notes (use investigation scratch/ for that). Retrospectives are end-of-session artifacts that preserve knowledge across /clear boundaries.

When It Triggers

TriggerDetails
Manual"retrospective", "capture what we learned", "save this for next time", "what did we learn", "log this experiment"
Auto-suggestAt approximately 20 substantive turns without a retrospective being captured

The auto-suggestion is a recommendation, not a gate — the user can decline:

"We've been working for a while without capturing learnings.
Consider running a retrospective before /clear — the failed
attempts table is the most valuable artifact, and it won't
survive a context reset."

The Experiment Registry

Registry entries are stored in scratch/registry/{YYYY-MM-DD}-{experiment-short-name}/SKILL.md and follow a strict format:

Setup Section

Each entry records the exact experimental configuration:

The Failed Attempts Table

This is the most valuable part of any registry entry. It prevents repeating mistakes across /clear boundaries and across team members.

AttemptWhat We TriedWhat HappenedWhy It Failed
1[specific change][specific result][root cause]
2[specific change][specific result][root cause]
Be Specific

Exact values, not vague descriptions. "learning_rate: 3e-4" not "small learning rate". "batch_size=256" not "large batch". The whole point is that someone (or a future Claude session) can reproduce or avoid these exact conditions.

Other Sections

Registry Structure

The registry lives in scratch/registry/ (gitignored):

scratch/registry/
  2026-03-15-rvq-depth-sweep/SKILL.md
  2026-03-18-fsq-codebook-size/SKILL.md
  2026-03-22-commitment-loss-scaling/SKILL.md

How It Feeds Back

Registry entries are searchable by the investigation skill. When a new investigation starts, matching entries are automatically surfaced based on the description and tags in each entry. This creates a feedback loop:

  1. Session A runs experiments and captures a retrospective
  2. Session A ends (or /clear happens)
  3. Session B starts a new investigation in a related area
  4. The investigation skill finds matching registry entries and surfaces them
  5. Session B avoids repeating Session A's failed attempts
Trigger Conditions Matter

The description field in the registry entry determines when it gets surfaced. Write trigger conditions that are hyper-specific: not "pruning experiments" but "pruning errors on ModelX with ZeRO2". This ensures the entry appears when it is actually relevant.

Key Principles

PrincipleDetails
Failed attempts > successesThey prevent repeating mistakes across /clear boundaries and across team members.
Hyperparameters must be exact"3e-4" not "small learning rate". "batch_size=256" not "large batch".
Trigger conditions must be specificThe description determines when the entry is surfaced. Make it match the exact scenario.
Scratch is temporaryThe registry lives in scratch/ (gitignored). When patterns are mature, distill them into the main codebase or docs.