State modeling
Ask for discriminated unions, exact optional fields, exhaustive switch handling, and impossible-state prevention.
🤖 TypeScript modeling prompt builder
TypeScript Type Design Prompt Generator
By Omellody Editorial Team · Published · UpdatedUse this existing Omellody prompt utility to turn messy API responses, UI states, validation needs, and edge cases into a type design prompt with discriminated unions, runtime validation notes, tests, and migration steps. The builder runs locally in your browser and does not send project details to Omellody.
Interactive prompt builder
Replace the examples with sanitized project details. The generated prompt updates locally in your browser.
Act as a senior engineer and careful reviewer. Help me create a TypeScript type design plan from the real context below.
Project context: {context}
Stack or tools: {stack}
Goal: {goal}
Constraints: {constraints}
Return these sections:
1. Direct recommendation with assumptions called out.
2. Inputs needed before acting and questions that block a reliable answer.
3. Decision table: option or hypothesis, evidence needed, risk, next action.
4. Step-by-step workflow with safe checks first.
5. Security, privacy, reliability, and maintainability review.
6. Tests, examples, or validation cases before merge or publication.
7. Rollback, escalation, and owner handoff plan.
8. Final checklist.
Rules: use only supplied facts, mark unknowns, avoid secrets or private data, do not invent undocumented behavior, and explain how to verify the result.
Copy-ready base prompt
Act as a senior engineer and careful reviewer. Help me create a TypeScript type design plan from the real context below.
Project context: {context}
Stack or tools: {stack}
Goal: {goal}
Constraints: {constraints}
Return these sections:
1. Direct recommendation with assumptions called out.
2. Inputs needed before acting and questions that block a reliable answer.
3. Decision table: option or hypothesis, evidence needed, risk, next action.
4. Step-by-step workflow with safe checks first.
5. Security, privacy, reliability, and maintainability review.
6. Tests, examples, or validation cases before merge or publication.
7. Rollback, escalation, and owner handoff plan.
8. Final checklist.
Rules: use only supplied facts, mark unknowns, avoid secrets or private data, do not invent undocumented behavior, and explain how to verify the result.
Prompt formula and variables
Formula: Domain states + source data + consumer code + impossible states + runtime validation + migration constraints + test matrix.
| Variable | What to enter |
|---|---|
{context} | Add specific, sanitized context details. If unknown, write the assumption explicitly. |
{stack} | Add specific, sanitized stack details. If unknown, write the assumption explicitly. |
{goal} | Add specific, sanitized goal details. If unknown, write the assumption explicitly. |
{constraints} | Add specific, sanitized constraints details. If unknown, write the assumption explicitly. |
Runtime boundary
Separate trusted internal types from parsed external data and require validation at API boundaries.
Migration and tests
Include compatibility shims, fixture examples, type tests, unit tests, and rollout notes for existing components.
Output review table
| Check | Pass condition | Fix if weak |
|---|---|---|
| Grounding | The answer distinguishes facts, assumptions, and unknowns. | Add source snippets, example inputs, or explicit non-goals. |
| Safety | No secrets, customer data, account identifiers, or destructive commands are requested. | Sanitize examples and ask for read-only checks first. |
| Actionability | The plan includes concrete steps, owners, tests, and rollback or review criteria. | Request a checklist with evidence and stop conditions. |
| Verification | The output can be tested with unit cases, logs, traces, fixtures, or source-of-truth docs. | Add expected results and failure examples before using it. |
Source snapshot
| Item | Snapshot |
|---|---|
| Page type | Existing Omellody coding prompt utility refreshed in Red Mode for depth and internal discovery. |
| Demand signal | URL inventory on 2026-05-22 flagged this prompt-family page as thin with limited internal-link depth while traffic radar continued to show AI prompt generator demand. |
| Originality | Omellody-created formula, builder, review criteria, FAQ, source snapshot, and safety guidance. No external repository content copied. |
| Last reviewed | 2026-05-22 |
Related coding prompt tools
FAQ
What should a TypeScript type design prompt include?
Include domain states, API shapes, UI consumers, impossible states, validation tools, compatibility constraints, and expected output format.
Should I ask for interfaces or type aliases?
Ask the model to recommend based on union modeling, extension needs, public API design, and project conventions.
How do I avoid invented API fields?
Tell the model to use only provided fields, mark unknowns, and produce follow-up questions instead of guessing.
Do TypeScript types replace runtime validation?
No. TypeScript helps at compile time; external API data still needs runtime validation and error handling.