--- name: api-roadmap-builder description: "Transforms an API surface area description into a phased delivery roadmap with versioned milestones, developer impact assessments, breaking-change classifications, dependency mapping, and a deprecation strategy. Use when planning the evolution of a public or internal API, sequencing endpoint releases, managing breaking changes across versions, or building a developer-facing roadmap for a platform or SDK." argument-hint: "[api-surface] [time-horizon]" allowed-tools: ["Read"] --- # API Roadmap Builder ## Purpose Turn a description of an API's current and intended surface area into a phased, milestone-driven roadmap that sequences work by dependency order and developer impact — so the team knows what ships when, which changes break consumers, and how versioning and deprecation are handled across the timeline. ## When to Use Invoke this skill when the user asks to: - Plan the evolution of a public, partner, or internal API over multiple quarters - Sequence new endpoints, fields, or capabilities into a release order - Manage breaking changes and version transitions across a developer base - Build a developer-facing API roadmap to share externally or with stakeholders - Plan an SDK or platform capability expansion tied to API changes - Define a deprecation and migration path for legacy endpoints ## Inputs Required Before starting, collect: - **Current API surface**: Existing endpoints, resources, or capabilities (or "greenfield" if net-new) - **Target capabilities**: What the API needs to support that it doesn't today - **Consumer profile**: Who calls this API — internal teams, partners, public developers, SDK users - **Time horizon**: Total span to plan (e.g., 2 quarters, 12 months) - **Versioning approach**: URL path, header, or none yet (default: assume no formal versioning exists and recommend one) - **Known constraints**: Dependencies, team capacity, compliance/security gates, or fixed deadlines - **Stability commitments**: Any backward-compatibility or SLA guarantees already made to consumers If versioning approach or stability commitments are missing, assume a public API with no formal versioning, recommend semantic versioning by URL path, and note the assumption. ## Instructions ### Step 1: Surface Area Inventory and Classification Catalog every capability — current and target — and tag each one: - **State**: Existing / Planned / Deprecating - **Type**: New resource / New endpoint on existing resource / New field / Behavior change / Removal - **Compatibility**: Additive (non-breaking) / Breaking - **Consumer impact**: None / Optional adoption / Required migration Group capabilities into logical capability clusters (e.g., "Auth & identity," "Webhooks," "Bulk operations"). Clusters become the unit of roadmap sequencing. ### Step 2: Dependency Mapping For each capability, identify what must exist first: - **Technical dependencies**: An endpoint that requires another resource, auth model, or data contract to ship first - **Sequencing dependencies**: Changes that should land together to avoid forcing consumers through two migrations - **External dependencies**: Third-party services, infra changes, or other teams' deliverables Flag any circular or ambiguous dependencies explicitly. A capability cannot be scheduled before its dependencies resolve. ### Step 3: Phasing into Milestones Break the time horizon into 3–5 sequenced phases. For each phase, name a theme and a developer-facing outcome. Order phases by these rules: - **Foundation first**: Auth, core resources, and data contracts that everything else depends on - **Additive before breaking**: Ship non-breaking capabilities early to build adoption before any forced migration - **Batch breaking changes**: Concentrate breaking changes into deliberate version boundaries — never trickle them out - **Deprecation tail last**: Removal of legacy surface comes after the replacement has shipped and a migration window has passed For each phase, define: - **Milestone name and target window** - **Capabilities shipping** (referencing the Step 1 inventory) - **Version impact**: New version, additive to current, or no version change - **Developer impact**: What consumers must do, can do, or experience automatically - **Exit criteria**: The condition that marks the phase complete ### Step 4: Breaking Change and Versioning Strategy For every breaking change in the roadmap: - **Classify the break**: Removed field/endpoint, changed response shape, changed default behavior, stricter validation, or auth change - **Migration path**: The concrete steps a consumer takes to move off the old behavior - **Coexistence window**: How long old and new run in parallel - **Communication trigger**: When consumers are notified relative to the change (e.g., changelog at announce, email at deprecation, hard cutoff date) Recommend a versioning scheme if none exists, and specify which phases introduce a new version. ### Step 5: Deprecation Plan For each capability being retired, define a four-stage lifecycle: 1. **Announce**: Marked deprecated in docs and response headers (e.g., `Sunset` header), replacement available 2. **Discourage**: Warnings in responses, new consumers blocked from adopting 3. **Sunset window**: Fixed date range; active consumers notified directly 4. **Removal**: Endpoint returns a clear error pointing to the migration guide Specify the minimum deprecation window appropriate to the consumer profile (internal: weeks; partner: a quarter or more; public: 6–12 months). ### Step 6: Risk and Dependency Notes Summarize the roadmap's structural risks: - Capabilities blocked on external dependencies (highest schedule risk) - Phases carrying multiple breaking changes (highest consumer risk) - Migration windows that overlap and could force consumers through back-to-back migrations - Any commitment in the inputs that the roadmap puts at risk ## Output Format - **Structure**: Inventory table → phased roadmap (one section per phase) → breaking change strategy → deprecation plan → risk notes - **Length**: 1,000–1,400 words - **Format**: Structured document — inventory and breaking changes as tables; phases as named sections with sub-bullets; risks as a prioritized list - **Sections**: Surface Area Inventory → Dependency Map → Phased Roadmap (3–5 phases) → Breaking Change & Versioning Strategy → Deprecation Plan → Risk & Dependency Notes - **Tone**: Technical product manager — precise, decision-oriented, written for both engineering and developer-relations readers ## Quality Checklist Before delivering output, verify: - [ ] Every capability in the inventory is tagged with state, type, compatibility, and consumer impact - [ ] No capability is scheduled in a phase before its dependencies resolve - [ ] Every breaking change has a classification, migration path, and coexistence window - [ ] Breaking changes are batched at version boundaries, not scattered across phases - [ ] Each deprecation follows the four-stage lifecycle with a specified window - [ ] Each phase has explicit exit criteria, not just a list of features ## Notes - The most common roadmap failure is forcing consumers through two migrations in close succession — check the deprecation windows against the phasing before delivering - Additive changes should dominate early phases; a roadmap that front-loads breaking changes will stall adoption - For public APIs, the deprecation window is a trust signal — under-promising the window and removing early damages developer confidence more than a longer timeline costs - If the inventory reveals no clean version boundary, recommend establishing one as the first phase's primary deliverable --- ## How to use this skill This file is a Claude Code skill in [Anthropic's standard format](https://docs.anthropic.com/en/docs/claude-code/skills) — markdown with YAML frontmatter at the top. **Installing in Claude Code:** - `~/.claude/skills//SKILL.md` — auto-loads in every session anywhere on your machine (recommended for skills you'll use across multiple projects) - `/.claude/skills//SKILL.md` — auto-loads only when working in that project (recommended for project-specific skills) Restart Claude Code or open a new session to register. **Using in Claude.ai, ChatGPT, Gemini, or other AI tools:** 1. 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