Developer Surface Strategist

Decide which developer surface should exist, why it exists, and what minimum contract makes it useful instead of just another way to call the same endpoint.

Use This For

• Choosing between SDK, CLI, MCP, GUI, REST/API, webhooks, and background agents.
• Explaining why someone would use an SDK instead of a CLI, MCP tool, or GUI.
• Planning Python SDK parity for a product that already has CLI or TypeScript affordances.
• Designing pd tube-style listener/sender workflows and code-generation briefs across languages.
• Making agent invocation easy enough that a user can create listeners and senders without memorizing infrastructure.

Do Not Use This For

• Implementing a full SDK or server runtime.
• Writing exhaustive API docs after the surface has already been chosen.
• Visual design, layout, or component polish.

Decision Process

flowchart TD
  A[Describe workflow] --> B{Who drives it?}
  B -->|Human repeats routine action| GUI[GUI or dashboard]
  B -->|Developer automates local action| CLI[CLI]
  B -->|Application embeds behavior| SDK[SDK]
  B -->|Model agent needs tool access| MCP[MCP tool]
  B -->|Service-to-service event| API[API or webhook]
  GUI & CLI & SDK & MCP & API --> C[Define shared contract]
  C --> D[Add language and onboarding parity]
  D --> E[Design receipts, examples, and tests]

1. Name the workflow and its actor: end user, developer, model agent, background worker, or external service.
2. Choose the primary surface by intent:
   • GUI for routine human operations and status.
   • CLI for local automation, scripts, and agent/operator emergency paths.
   • SDK for embedding Port Daddy behavior in an app, service, or library.
   • MCP for model clients that need safe tool calls.
   • API/webhooks for service integration and external systems.
3. Define the shared contract once: message schema, auth, idempotency, receipts, errors, and telemetry.
4. Add parity expectations by language. If Python developers are a target audience, require a Python SDK plan.
5. For pd tube workflows, specify listener, sender, channel naming, message schema, auth, retry, receipt, and codegen targets.
6. Use scripts/surface_matrix.mjs to generate a deterministic surface recommendation and gap list.

Output Contract

Return:

• surfaceMatrix: workflows with primary and secondary surfaces.
• rationale: why each surface exists and what it must not do.
• tubeWorkflow: listener/sender contract, schema, receipt, and codegen targets.
• sdkParity: language list, Python SDK requirement, examples, tests, and release criteria.
• onboarding: how a new user discovers the right surface without reading the source.

Anti-Patterns

Everything Is A CLI

Novice: "Power users can run commands." Expert: Routine operator tasks need GUI affordances. CLI is for agents, scripts, and emergencies. Timeline: By 2026, agentic products must distinguish human control surfaces from automation surfaces. Detection: Signup, credentials, restart, status, or feedback require terminal commands.

SDK As Fancy API Wrapper

Novice: "An SDK is just generated REST calls." Expert: An SDK should encode workflows: auth setup, typed messages, retries, idempotency, receipts, local fixtures, and examples. Timeline: Agentic SDKs need safety defaults and workflow helpers, not only endpoint coverage. Detection: SDK plan has method names but no examples, no retry/receipt semantics, and no local test fixture.

MCP For Everything

Novice: "If a model might use it, make it MCP-only." Expert: MCP is excellent for model tool access, but applications still need SDK/API surfaces and humans still need GUI/CLI. Timeline: Modern agent systems work best when MCP is one adapter over a shared contract, not the source of truth. Detection: No non-MCP path for services, scripts, or humans.

References

File	Load When
references/surface-decision-guide.md	Need SDK vs CLI vs MCP vs GUI decision rules.
references/tube-workflow-patterns.md	Need listener/sender workflow and multi-language codegen requirements.
examples/expected-output.md	Need the shape of a finished surface matrix.
templates/output-template.md	Need a reusable surface strategy template.
schemas/surface-strategy.schema.json	Need the JSON input contract for the surface matrix.
scripts/surface_matrix.mjs	Need deterministic surface recommendations and gap checks.
agents/openai.yaml	Need a subagent descriptor for delegated developer-surface strategy.

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Skill Bundle Index

root

• CHANGELOG.md - Changelog for this skill.
• README.md - Quick start and purpose.

agents/

• agents/openai.yaml - OpenAI/Codex-style agent descriptor for surface strategy.

examples/

• examples/expected-output.md - Example surface matrix and tube workflow brief.

references/

• references/surface-decision-guide.md - Decision rules for SDK, CLI, MCP, GUI, API, and webhooks.
• references/tube-workflow-patterns.md - Listener/sender workflow patterns and codegen requirements.

schemas/

• schemas/surface-strategy.schema.json - JSON contract for surface_matrix.mjs.

scripts/

• scripts/surface_matrix.mjs - Builds surface recommendations and gap lists.

templates/

• templates/output-template.md - Copyable surface strategy template.

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