[Backup] az backup: Add Cross Subscription Backup (CSB) support for A…

[Prabhkiratnitp]

…zure VM

• az backup protection enable-for-vm: accept a full VM ARM id in a different subscription than the vault (CSB); skip discovery and construct the container/protected-item URIs and sourceResourceId directly, after validating the VM exists and is in the vault's region
• az backup restore restore-disks: support OLR for CSB protected items by deriving the container subscription from the item sourceResourceId; fail with a clear error when a friendly container name matches multiple containers
• az backup item list/show: add containerSubscriptionId to the Azure VM backup item response
• az backup job show: add containerSubscriptionId to the Azure VM backup job response
• Add tests, recording, help examples and history notes

Related command

Description

Testing Guide

History Notes

[Component Name 1] BREAKING CHANGE: az command a: Make some customer-facing breaking change
[Component Name 2] az command b: Add some customer-facing feature

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Pull request overview

This PR extends the az backup command module to support Cross Subscription Backup (CSB) scenarios for Azure VM protection and restore, and surfaces the protected VM’s subscription on item/job responses to help customers operate across vault/VM subscription boundaries.

Changes:

• Enable az backup protection enable-for-vm to accept a full cross-subscription VM ARM ID and bypass protectable-item discovery by constructing container/item URIs directly.
• Improve restore flows for CSB, including Original Location Recovery behavior and clearer failures when friendly names are ambiguous.
• Add containerSubscriptionId to Azure VM backup item and job outputs, plus tests/recordings/help/history notes.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/azure-cli/HISTORY.rst	Adds history notes documenting new CSB behavior and response fields.
src/azure-cli/azure/cli/command_modules/backup/tests/latest/test_backup_commands.py	Adds validation for containerSubscriptionId on Azure VM backup items and introduces a playback-only ambiguity regression test.
src/azure-cli/azure/cli/command_modules/backup/tests/latest/recordings/test_backup_restore_multiple_containers_same_friendly_name.yaml	Recording supporting the new ambiguity regression scenario.
src/azure-cli/azure/cli/command_modules/backup/custom.py	Implements CSB enable-for-vm path, ambiguity validation, OLR subscription derivation, and job response augmentation.
src/azure-cli/azure/cli/command_modules/backup/custom_help.py	Adds helpers to surface containerSubscriptionId for items/jobs.
src/azure-cli/azure/cli/command_modules/backup/custom_common.py	Ensures item list/show consistently set containerSubscriptionId.
src/azure-cli/azure/cli/command_modules/backup/_help.py	Adds help examples/long-summary guidance for CSB/native names.

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Backup

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