build-app-step01
Convert OpenAI's "15 lessons from building ChatGPT apps" into an execution workflow that prevents common mistakes early.
When to use
Use this skill when the user is:
- •Building a new app and wants risk prevention before coding.
- •Shipping ChatGPT Apps, MCP servers, tool-calling agents, or widgets to production.
- •Asking for engineering SOP/checklist/guardrails instead of one-off fixes.
- •Turning scattered lessons into repeatable team process.
Do not use this skill for purely conceptual Q&A or isolated UI-only tweaks.
Inputs you must collect first
Collect these five inputs before proposing implementation:
- •Product goal: one sentence user outcome.
- •User context: data sources, auth, environments.
- •Risk profile: security, latency, compliance, wrong-answer cost.
- •Integration surface: tools, MCP servers, widgets, external APIs.
- •Acceptance gate: what must pass before launch.
If any input is missing, ask one focused question at a time.
Workflow (preventive, stage-gated)
Stage 1: Scope and architecture gate
- •Decompose into explicit systems:
- •What: product requirements and user journeys.
- •How: implementation, tool orchestration, deployment.
- •Choose architecture mode intentionally:
- •Stateless API flow for simple requests.
- •Stateful chat flow for iterative conversations.
- •Hybrid mode when both are needed.
- •Add observability plan before coding:
- •request IDs, tool call logs, model config logs.
Read: references/15-lessons-mapping.md sections L1-L3.
Stage 2: Prompt and context gate
- •Keep prompt rules short and operational.
- •Prefer structural guardrails over huge prompts.
- •Detect and recover from context-window pressure.
- •If behavior drifts, run evals instead of adding random prompt text.
Read: references/15-lessons-mapping.md sections L4-L8.
Read: references/code-patterns.md sections "Prompt + context" and "Tracing".
Stage 3: Tooling and integration gate
- •Design tool contracts first (input/output schema, timeout, retries).
- •Treat tool calls as untrusted boundaries; validate all payloads.
- •Use MCP to separate model orchestration from system capabilities.
- •Include fallback paths when a tool is unavailable.
Read: references/15-lessons-mapping.md sections L9-L12.
Read: references/code-patterns.md section "Tool contracts".
Stage 4: Ship gate
- •Run preflight checks locally.
- •Run smoke tests on real flows.
- •Verify security and data handling rules.
- •Document rollback path before release.
Run: scripts/preflight_check.sh
Run: scripts/generate_checklist.sh
Stage 5: Growth and operations gate
- •Define eval datasets for top user intents and failure modes.
- •Track quality over time; never assume prompts stay stable.
- •Use fast experiment loops with clear win/loss metrics.
Read: references/15-lessons-mapping.md sections L13-L15.
Output format required from the assistant
When using this skill, return results in this order:
- •Conclusion first (MVP path).
- •Detailed explanation by stage.
- •Implementation steps.
- •Minimal code snippets (only what is required).
- •Task checklist.
- •Risks and rollback.
- •Validation commands and expected outcomes.
- •Source used.
Non-negotiables
- •Do not put keys/tokens in code or logs.
- •Do not introduce unverified APIs or packages.
- •Every change must be reversible.
- •API changes must include caller/type/doc updates.
Quick runbook
- •
bash scripts/preflight_check.sh - •
bash scripts/generate_checklist.sh > /tmp/build-app-step01-checklist.md - •Use generated checklist in planning/review before implementation.
Source
Primary source:
- •https://developers.openai.com/blog/15-lessons-building-chatgpt-apps (published 2026-02-04)