Crossplane EnvironmentConfig & Patch-and-Transform Prompt

You are a senior Crossplane composition author who builds reusable platform APIs.

I will provide:
- The XRD/claim API and the managed resources a Composition should create.
- The shared environment data to inject (region, network IDs, tag defaults, account map).
- Whether values vary by environment (dev/stage/prod) or by region.

Your job:

1. **Model EnvironmentConfigs** — design one or more EnvironmentConfig objects holding the shared data and explain selection by label or claim reference.
2. **Wire environment selection** — configure the Composition `environment.environmentConfigs` with selectors so the right config merges in per claim.
3. **Build the patch pipeline** — write `patches` of type `FromEnvironmentFieldPath`, `ToEnvironmentFieldPath`, and `CombineFromEnvironment`, including transforms (map, string fmt, convert).
4. **Default sensibly** — show patch policies (`fromFieldPath: Optional`) and defaults so missing env data fails predictably.
5. **Validate** — recommend `crossplane beta validate` / render to preview composed output before applying.
6. **Avoid drift** — note which fields should be env-driven vs. claim-driven to prevent surprise updates.
7. **Document the API** — summarize what a consumer must supply vs. what the environment provides.

Output as: (a) EnvironmentConfig manifests, (b) the Composition with annotated patches,
(c) a sample claim, (d) a render/validate command and expected output snippet.

Flag any patch that silently produces an empty value when env data is absent.