# Diagnose Before Plan

> Diagnose failures before creating a Prime Agent plan. MUST USE for bugs, CI failures, test failures, regressions, incidents, broken behavior, root cause, RCA, or debug-why requests before deciding whether to plan; preserve language, reviewer, and criticizer settings in `.git/prime_plans/config.json`; exclude ordinary feature planning, direct implementation-only, factual/explanation, trivial command-only, or explicit no-plan requests.

- Skill: `optim-agent/diagnose-before-plan` (Agent Skill)
- Install (CLI): `npx skillmds@latest add optim-agent/diagnose-before-plan`
- Raw SKILL.md: https://api.skillmd.com/api/skills/optim-agent/diagnose-before-plan/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: Optim-Agent (https://skillmd.com/u/optim-agent)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/optim-agent/diagnose-before-plan

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# Diagnose Before Plan

Use this skill for problem or failure inputs that need diagnosis before planning.

## Prime Agent Setup

Read `../../../../references/prime-planning-workflow.md` and `state-and-config.md` — both normative — and follow their setup, state, `language`, and reviewer/criticizer rules. State lives in `.git/prime_plans/` via `../../../../scripts/prime_plans_state.py init --workdir <target-workdir>`; spawn reviewer/criticizer roles with `await rlm(...)`.

## Diagnostic Workflow

1. Inspect available evidence first: repository files, logs, tests, command output, stack traces, recent diffs, CI output, environment details, and user-provided symptoms.
2. Produce an in-message RCA summary before asking whether to plan. Use at most 5 Whys. Stop with `unknown` when evidence is insufficient; do not invent a cause.
3. Ask one choice prompt in the configured language that includes the RCA summary:
   1. `Create the scoped fix plan` - recommended when evidence supports a planning path.
   2. `Stop after RCA` - keep the diagnosis only.
   3. `Other`.
   4. `Auto-complete`.
4. On opt-out, stop after the summary; do not write `PROBLEM_ANALYSIS.md`.
5. On opt-in (or `Auto-complete` choosing the recommendation), select the smallest fitting planning skill and follow that skill exactly: first-turn planning question, final scope confirmation, `PLAN_v1.md`, refinement, and the native Prime Agent execution handoff.

## Level Selection

- `create-a-small-plan`: clear root cause, obvious fix shape, few local files, limited risk.
- `create-a-plan`: multi-file fix, external API or dependency behavior, compatibility concerns, or research needed.
- `create-a-big-plan`: cross-system failure, unclear root cause, redesign pressure, or high safety/recoverability risk.

Do not ask the user to choose the level unless the evidence supports two materially different planning depths and the tradeoff cannot be resolved from the repo.

## PROBLEM_ANALYSIS.md

After opt-in, create the selected planning run's `.git/prime_plans` state and public artifact directory, then write `PROBLEM_ANALYSIS.md` before `PLAN_v1.md`. Include: original problem; symptoms and reproduction status; evidence inspected; RCA summary and 5 Whys (ending early with `unknown` when evidence stops); suspected root cause and confidence; planning skill selected and why; language, reviewer, and criticizer settings used; open diagnostic gaps the plan must address. Pass the original problem, RCA summary, evidence, and `PROBLEM_ANALYSIS.md` into the selected planning skill.