codex-sdd:plan

OpenSpec Plan

Context

Plan is the second phase of the OpenSpec workflow. It transforms an approved proposal into two artifacts:

• design.md — Technical architecture, API contracts, data design, decisions
• tasks.md — Executable task breakdown This is the "constrain the implementation" step.

Trigger

Any of these patterns triggers this skill:

• User says "openspec plan" or "openspec:plan"
• User confirms the proposal scope
• openspec_get_status shows phase is plan or phase is propose with confirmed scope

Prerequisites

• An active proposal at openspec/changes/<changeId>/proposal.md
• Scope has been confirmed by the user

Workflow

Step 1: Read the Proposal

Call openspec_read_artifact({ artifactId: "proposal" }) to understand the requirement scope and constraints.

Step 2: Build Context

Call docs_build_context using keywords from the proposal. Include likely spec domains and modules when known. The design should cite relevant source paths from openspec/specs, docs/generated, docs/reviewed, or docs/knowledge when they affect interfaces, compatibility, risks, or task sequencing.

Step 3: Generate Design

Use openspec_create_or_update_artifact with detailed technical analysis:

openspec_create_or_update_artifact({
  artifactId: "design",
  content: "<technical design markdown>"
})

For best results, you should analyze the proposal and generate a thorough technical design covering:

• Overall architecture approach
• New/modified interfaces (API endpoints, function signatures)
• Data model changes
• Caching strategy
• Concurrency/locking considerations
• Compatibility with existing systems
• Risks and edge cases

Write the full design to openspec/changes/<changeId>/design.md.

Step 4: Generate Tasks

After design is created, generate tasks:

openspec_create_or_update_artifact({
  artifactId: "tasks",
  content: "<checkbox task markdown>"
})

This creates or updates openspec/changes/<changeId>/tasks.md with check-box tasks.