Double Check

/double-check

Multi-pass re-verification of a plan, output, decision, or document — re-read from scratch, challenge assumptions, propose improvements, and iterate until solid.

> Re-Read & Improve Protocol — not a single-pass gate. The agent re-reads the target fresh, challenges each part, proposes improvements, and iterates. Each pass tightens the result.

> Structured execution spec: [protocol.yon](protocol.yon). It carries the five phases, the scope/verdict gates, and the rules as validatable records; this file is the explanation. Keep the two in sync — edit one, update the other and refresh the @STAMP date.

> Caller Options. Before executing, run the Caller Options protocol (caller-options/SKILL.md): triage this invocation for material optionality across the venues and modes declared in front-matter; if one path clearly dominates, proceed silently; otherwise surface the options to the caller. A resolved-invocation marker means COP already ran — execute the fixed combination directly, do not re-enter COP.

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Phase 1: Scope

Identify what is being double-checked — a plan, an output, a decision, a document. Load it fresh. Do not rely on prior context or cached understanding.

Gate: Cannot double-check without a clear target. If the target is ambiguous, ask before proceeding.

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Phase 2: Fresh Re-Read

Re-read the target from scratch as if seeing it for the first time. Go back to the actual sources — files, code, docs. Do not verify from memory or prior analysis alone.

Summarize:

• What it says
• What it assumes (implicit and explicit)
• What it depends on

List every assumption, stated or unstated.

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Phase 3: Challenge

Challenge each part of the target. Be adversarial — actively try to find problems.

For plans: Are any steps wrong, missing, out of order, or unnecessary? For outputs: Are any claims unsupported? For decisions: Were alternatives considered?

Look for:

• Gaps and omissions
• Wrong or unstated assumptions
• Over-engineering or under-engineering
• Scope issues
• Ordering issues
• Missing dependencies

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Phase 4: Improve

Propose concrete improvements based on the challenge findings.

For each issue found:

1. State the problem
2. Propose the fix
3. Explain why it's better

If the target is already solid, say so with evidence — but don't stop looking just because it seems fine.

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Phase 5: Verdict

Deliver one of three verdicts:

• SOLID — target holds up under scrutiny; cite evidence
• IMPROVED — issues found and fixes proposed; list them; offer to apply and run another pass
• RETHINK — fundamental problems; explain what needs to change

Gate: Double-check is incomplete without a verdict delivered to the user.

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Rules

• MUST go back to actual sources when re-reading — never verify from memory or prior analysis alone
• MUST be adversarial when challenging — actively look for problems, don't just confirm
• MUST cite evidence for every conclusion in the verdict
• MUST NOT rubber-stamp without substantive analysis
• SHOULD offer to apply fixes and run another pass when verdict is IMPROVED

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Next Steps

• /plan-execute — if verdict is SOLID
• /plan-create — if verdict is RETHINK (redesign needed)

> Human output. This skill's handler-facing output obeys the human-output > contract (human-output/SKILL.md).

> Self-improvement. On completion, run the Self-Improvement Protocol (self-improve/SKILL.md): if this run surfaced a concrete, blocking-or-recurring weakness in this skill, propose a specific fix for the handler to approve. Conservative — silent otherwise. Never auto-apply.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: allemaar
• Source: allemaar/open-skills
• License: Apache-2.0
• Homepage: https://allemaar.com

Install and usage instructions live in the source repository linked above.