Define intended behavior, review write scope and assess reversible decisions. Use when: acceptance or approach is unclear before coding; stop once actionable.

Plan Shape missing intent into one actionable slice, then stop. A clear change can proceed directly; load a specialist only for the question it answers. Prefer the caller's tracker, if any; otherwise use the conversation or supplied text. Supplied advice, such as an [Idea Genie](../idea genie/SKILL.md) portfolio or challenge, is evidence to weigh, never a decision. A plan meets these rules 1. One slice, not a roadmap. Shape the narrowest change that produces an observable result end to end, through every layer it touches. No phases, no layer by layer breakdown, no backlog: later work stays one coarse line each until new evidence makes it the next slice. When several slices could go first, prefer the smallest observable path that tests the approach's riskiest dependency. Outcomes that are each useful and checkable alone are separate plans, not slices: unless the request, the tracker or Navigate already settles which comes first, ask (rule 3) and keep the rest under Later. Named providers, devices or data sources are coverage of one outcome; separate them only when no shared path can meet a named requirement, and keep parts together when specifying one alone would mean guessing behavior it shares with another. Name any stand in and what it cannot establish; a demonstration with that stand in is not proof of the real integration. 2. An example before any design. Write at least one Given/When/Then with an observable result. Cover the boundary where a mistake is costly to undo, such as a repeated or external side effect, lost data or widened access, not only the happy path. 3. Look up facts; ask only for choices. Read code, docs and the tracker instead of asking. Ask the caller at most one question, only for a choice no source can answer, with your recommendation and its tradeoff. When several choices compete for it (which outcome comes first, a rule 7 conflict, a recorded decision under [Who decides]( who decides)), ask the one that most changes the slice and list each other under Later with what it would change. If several block acceptance, [Interview](../interview/SKILL.md) settles them one per turn. 4. The repository's words. Reuse the term its code, glossary or tracker defines; never coin a parallel name. 5. Scope by consumer. Name the owners to edit, every live caller and test of the changed behavior, and generated companions as a class, as repository relative patterns. Scope is authority, not a predicted file count: a live consumer outside it goes to the caller as an exact file amendment, while independent in scope work continues. 6. A discriminating check: what fails today and passes after the slice. 7. Unrequested mechanisms earn their place. A guard, retry, fallback, option or abstraction nobody asked for joins the slice only when a contract requires it, when without it a traced failure would go unseen by anyone able to fix it in time, or when adding it later is costly: persisted data or formats, interfaces others depend on, payments, security. Use its smallest form and judge each add on the same way; when unsure, leave it out and name it under Later with the evidence that would require it. If a failure of the slice would reach no one who can act, making it visible is part of the slice. No safeguard narrows requested behavior; a real conflict is the Question. Output Write this block into the caller's existing intent when the request or existing authorization covers editing it (the conversation always does); otherwise return it as a proposed amendment. It is the whole plan. Add an Example line only for another consequential boundary, an Open line for a fact only a named person holds (with the drafted questions), and a non goal only where it prevents a plausible scope mistake. Workflow 1. Read the accepted intent, any existing plan or native handoff, and the relevant source owners and active constraints. Reuse the acceptance already supplied in the conversation or bead; clarify only what prevents action or judgment. To resume, hand a slice on, pair code with a retrospective or snapshot intent, follow [resume and handoff](references/resume and handoff.md). 2. Route only the uncertainty that could change the slice (table below). If an interface choice drives that uncertainty, use the conditional [caller first design comparison](references/ground truth routing.md compare interfaces from the callers side) before committing to a boundary. 3. Fill the block. If a behavior preserving restructuring would make the slice much smaller, name it on the Slice line as a precondition through [Refactor](../refactor/SKILL.md), with its own before and after check separate from the Check line, and keep it out of the slice's diff. A mechanical cross cutting migration that cannot stay working slice by slice uses expand, migrate, contract and says where integration is required. If recorded evidence (scorecards, fixtures) is bound to files the slice changes, plan its recapture; with the ao CLI, which the plugin does not ship, ao provenance evidence orphans root <repo root changed <path lists those bindings. Across an epic, [Navigate](../navigate/SKILL.md) picks the next bead; Plan shapes that bead. 4. When evidence disproves an approach, keep the failed assumption, its evidence and the revised check in the existing intent, under the same authority as the Output write below. An approach change within accepted outcome and scope needs no new permission; acceptance or scope expansion needs the caller. Never relabel a failed acceptance condition as a caveat to obtain green. Stop planning once the implementer can act and the validator can judge. More research, decomposition or review must resolve a named remaining uncertainty; reserve capacity for implementation, integration and repair. Route uncertainty Uncertainty Next action Fact a source can answer Inspect the smallest authoritative source and cite it. [Research](../research/SKILL.md) owns deeper tracing; [Domain](../domain/SKILL.md) owns disputed vocabulary. Never ask the caller to recite it. Caller choice Recover existing authorization first. What remains is the one question, with its concrete tradeoff; an agent cannot supply the caller's answer. Fact only a named other person holds Name the person and draft the few questions the gap needs, most consequential first, one idea each, with enough context to answer; return them with the plan, and the caller decides whether and how to send them. The item stays open until answered; never guess it or recast it as a caller choice. Assumption only an observation can settle State the competing predictions and the smallest observation that separates them, using an optional [probe or prototype](references/ground truth routing.md). A persuasive design or an agent vote cannot settle unobserved behavior. Safely deferred Put it under Later with the event or evidence that would make it relevant. Deferral cannot hide an unanswered acceptance condition. Resolve reversible implementation details within accepted scope. Mark inference and missing evidence; never promote either into a source fact or a settled caller choice. For consequential uncertainty that survives source checks and observation, an optional [challenge](references/challenge.md) returns advice or a next discriminator, never permission or acceptance. [Memory recall](../memory/references/recall.md) helps only when prior evidence could change the next action. Who decides Use real undo cost, affected users and existing authority. A material irreversible choice outside that authority goes to the caller, as does a slice that would cut against a recorded decision such as an ADR, a published contract or a declared non goal: name that decision and the evidence for reopening it as the Question, and keep the slice within it until the caller answers. Prior authorization stays valid. Reviewer agreement is evidence, not permission to replace the caller's intent: explain a consequential disagreement and its support instead of silently changing acceptance. A proposed process artifact needs a concrete consumer, the decision it gates, an observed defect and a retirement condition; otherwise omit it. Example An example can be plain text; BDD needs no .feature file or interview. In a repository that calls queued work a Job (write "Job", not "task item"): Given a Job has already completed, when the worker receives it again, then its completed result is returned and its side effect is not repeated. Tests added after coding may supplement the accepted example but cannot redefine what was promised.