postman-openapi-converter

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• SKILL.md

SKILL.md (first lines)

# OpenAPI → Postman Collection Converter

Converts **OpenAPI 3.x** or **Swagger 2.0** specs into a valid **Postman Collection v2.1**.

---

## Step 1 — Detect & Validate Input

Identify the spec version from the input:
- `openapi: 3.x.x` → OpenAPI 3
- `swagger: "2.0"` → Swagger 2

If the input is truncated or partial, convert what's available and note missing sections.

---

## Step 2 — Extraction Mapping

### OpenAPI 3 → Postman

| OpenAPI field | Postman mapping |
|---|---|
| `info.title` | Collection name |
| `info.description` | Collection description |
| `servers[0].url` | `{{base_url}}` variable |
| `paths.<path>.<method>` | One request item per operation |
| `operationId` or `summary` | Request name |
| `parameters` (path/query/header) | URL path variables, query params, headers |
| `requestBody.content.application/json.schema` | Body (raw JSON), generate example from schema |
| `responses` | Saved example responses |
| `components.securitySchemes` | Collection-level auth |
| `tags` | Folder grouping |

### Swagger 2 → Postman

| Swagger field | Postman mapping |
|---|---|
| `host` + `basePath` | `{{base_url}}` |
| `paths.<path>.<method>` | Request item |
| `parameters` | Query/path/header/body params |
| `consumes` / `produces` | Content-Type / Accept headers |
| `securityDefinitions` | Collection auth |
| `tags` | Folders |

---

## Step 3 — Generate Example Bodies

For each request with a `requestBody` or `body` parameter, generate a realistic example JSON body from the schema:
- Use property names as keys
- Infer sensible example values from type + format (e.g., `"email"` format → `"user@example.com"`, `"date-time"` → `"2024-01-15T10:30:00Z"`)
- For `$ref` schemas, resolve them inline

---

## Step 4 — Auth Handling

Map security schemes to Postman auth:

| OpenAPI scheme | Postman auth type |
|---|---|
| `http: bearer` | `bearer` with `{{token}}` |
| `http: basic` | `basic` with `{{username}}` / `{{password}}` |
| `apiKey: header` | `apikey` header with `{{api_key}}` |
| `apiKey: query` | `apikey` query param |
| `oauth2` | `oauth2` (note: requires manual token setup) |

Apply auth at **collection level** if all endpoints share the same scheme. Override at request level for exceptions.

---

## Step 5 — Build Collection JSON

Use the standard v2.1 structure (same schema as postman-collection-generator skill).

Key differences for spec-converted collections:
- Always group by `tags` into folders
- Include `description` field on each request from `operationId` + `summary` + `description`
- Add saved example responses where `responses` are defined in the spec

```json
"response": [
  {
    "name": "200 OK",
    "status": "OK",
    "code": 200,
    "header": [{ "key": "Content-Type", "value": "application/json" }],
    "body": "{ \"id\": 1, \"name\": \"example\" }",
    "originalRequest": { <copy of the request> }
  }
]
```

---

## Step 6 — Environment File

Extract all variables into a companion environment:
- `base_url` from `servers[0].url` or `host + basePath`
- `token`, `api_key`, `username`, `password` as empty placeholders
- Any server variables from `servers[0].variables`

---

## Step 7 — Output

1. `collection.json` — Full Postman Collection v2.1
2. `environment.json` — Matching environment file
3. **Conversion summary**: number of endpoints converted, folders created, auth type detected, any fields skipped or approximated
4. Import instructions

---

## Edge Cases

- **`$ref` chains**: Resolve all `$ref` pointers inline before mapping
- **`allOf` / `oneOf` / `anyOf`**: Use the first/primary schema for body generation; note alternatives in description
- **Path parameters**: Convert `{param}` to `:param` in URL path AND add to `variable` array in url object
- **Multiple content types**: Prefer `application/json`; note others in request description

From LambdaTest/agent-skills, MIT.

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