docs(api): document CE type generation [BE-13031] (#2794)

Co-authored-by: Claude <noreply@anthropic.com>

CONTRIBUTING.md

@@ -149,6 +149,8 @@ When adding a new route to an existing handler use the following as a template (
 
 explanation about each line can be found (here)[https://github.com/swaggo/swag#api-operation]
 
+After changing these annotations, regenerate the TypeScript API client and types — see [Generating API types](./README.md#generating-api-types).
+
 ## Licensing
 
 See the [LICENSE](https://github.com/portainer/portainer/blob/develop/LICENSE) file for our project's licensing. We will ask you to confirm the licensing of your contribution.

README.md

@@ -44,6 +44,32 @@ You can join the Portainer Community by visiting [https://www.portainer.io/join-
 - Want to report a bug or request a feature? Please open [an issue](https://github.com/portainer/portainer/issues/new).
 - Want to help us build **_portainer_**? Follow our [contribution guidelines](https://docs.portainer.io/contribute/contribute) to build it locally and make a pull request.
 
+## Generating API types
+
+The frontend consumes a TypeScript API client (SDK functions and request/response types) that is generated from the Go API's Swagger annotations. Regenerate it after any API change — a new endpoint, a changed request/response shape, or a removed endpoint:
+
+```bash
+make generate-api
+```
+
+This runs the following pipeline:
+
+```
+Go Swagger annotations
+  → dist/docs/swagger.yaml       (make docs-build, via swaggo/swag)
+  → dist/docs/openapi.yaml       (swagger2openapi + validation)
+  → app/react/portainer/generated-api/portainer/   (hey-api/openapi-ts)
+```
+
+The generator is configured in [`openapi-ts.config.ts`](./openapi-ts.config.ts), which controls the output path, plugins, and tag filters (for example, `deprecated` endpoints and `edge_agent`-tagged routes are excluded).
+
+The generated files live in `app/react/portainer/generated-api/portainer/` and must **not** be edited by hand — your changes would be overwritten on the next run. Import the generated SDK functions and types instead of writing direct HTTP calls:
+
+- `@api/sdk.gen` — SDK functions
+- `@api/types.gen` — request/response types
+
+See [Adding api docs](./CONTRIBUTING.md#adding-api-docs) for how to annotate handlers so they are picked up by the generator.
+
 ## Security
 
 For information about reporting security vulnerabilities, please see our [Security Policy](SECURITY.md).