writing-plans

name	writing-plans
description	Use when an approved PRD needs an implementation-authoritative FSD before code is written.

Writing Plans

Turn an approved PRD into the FSD authority consumed by /sc-work. Announce: "I'm using writing-plans to create the FSD and goal slices."

When to Use

Use after BRD/PRD approval and before implementation. Do not plan from memory, invent missing product policy, or proceed while an OPEN-* blocker prevents a safe technical contract.

Route

1. Search before loading: locate the approved PRD, qualified BRD refs, existing FSD/state, accepted ADRs, nearby code/tests, and relevant solution notes.
2. Load FSD authoring for evidence selection, risk branches, contract shape, acceptance, and handoff.
3. After the contract is stable, load goal slicing only when defining GOAL-* packets, a task ledger, or a measured wide refactor.
4. Read only the needed sections of the full FSD template; never preload it merely to orient.

Invariants

• Save the primary authority to docs/fsd/fsd-<feature>.md; a companion plan never outranks it.
• Trace qualified BRD/PRD IDs, approved TDEC-*, optional accepted ADRs, tests, and goals. Missing authority becomes an OPEN-* blocker.
• State exact contracts, affected paths, failure modes, rollback, verification commands, and expected evidence.
• Prefer a thin vertical slice that delivers one independently verifiable behavior.
• A wide refactor is an exception: name the shared seam, enumerate affected callers, bound the file surface, and provide verification covering every caller plus migration/rollback. “Many files” alone is not justification.
• Never defer compatibility, security, privacy, data, or UI evidence until implementation.
• For UI-bearing scope, use the canonical UI readiness reference, make FSD Section 8 the Screen & Interaction Contract, and keep exact wire shape in a delegated versioned machine contract.
• Define a contract enabler when executable assets are missing, then exactly one first real vertical slice before any dependent scale-out goals.

Red Flags

Thought	Response
"The FSD is obvious"	Write exact contracts and evidence.
"One horizontal layer is cleaner"	Use a vertical slice unless the measured wide-refactor exception applies.
"Tests can wait"	Map verification beside each risky goal.
"We can choose the package later"	Resolve compatibility and supply-chain risk first.

Integration

Inputs: agentic-delivery, prd-generator, domain/codebase evidence. Risk branches: compatibility-check, threat-modeling, data-privacy, interface-design. Outputs: plan-verification, issue-workflow, executing-plans, and verification-before-completion.