fix(cloud): default to automatic underlying cloud selection

[Guilherme Penedo (guipenedo)]

Change

launch_cloud() currently forces Modal workers onto AWS by default and rejects cloud=None. Default to None across single pipelines, pipeline sequences, the launcher, and serialized runtime requests so the execution backend can choose the underlying cloud.

Explicit aws, gcp, and oci values remain supported; invalid values are rejected. Region defaults and filtering are unchanged. Customer docs explain how cloud selection differs from the execution backend.

Validation

• Focused launcher tests: 88 passed; platform client tests also passed.
• Repository-wide Ruff lint, formatter check, and type check pass; pre-commit hooks pass.
• Full SDK test suite: 1,386 passed, 25 skipped (existing TensorFlow isolation and GPU-only skips).
• Tests cover default null serialization, explicit None, explicit cloud choices, multi-stage propagation, and invalid values.

Rollout dependency

Deploy https://github.com/macrodata-labs/perpetuity/pull/963 before releasing this change. Older controllers silently replace null/missing cloud with AWS. Existing jobs that explicitly request AWS are unaffected. No live cloud job was modified during this work.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-15T14:59:34.037866Z	d507ce6	PR opened

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