Describe the bug

When multiple extensions are tested sequentially in CI, a stale commandIndex.json can cause the second extension's commands to never override the core CLI module's commands. This results in incorrect API version being used, causing all VCR-recorded scenario tests to fail.

Root Cause
azdev extension add (in azdev/operations/extensions/__init__.py) installs extensions via raw pip install -e, but does not call CommandIndex().invalidate() afterward. The CLI's own az extension add properly invalidates the command index (azure-cli-core/extension/operations.py L352), but azdev bypasses this path entirely.

Similarly, azdev extension remove uses pip uninstall without invalidating the index.

How the Failure Occurs
The CI test runner (test_source.py) tests multiple extensions sequentially:

for pkg_name, ext_path in ALL_TESTS:
    azdev extension add ext_name      # No index invalidation!
    azdev test ... pkg_name
    azdev extension remove ext_name   # No index invalidation!

When the list order is [oracle-database, aks-preview]:

1. azdev extension add oracle-database — installs oracle-database (no index invalidation)
2. azdev test oracle-database — during test discovery, az cloud show is invoked, which triggers MainCommandsLoader.load_command_table(). This creates commandIndex.json mapping aks → ['azure.cli.command_modules.acs'] (core module only, since aks-preview is not installed yet)
3. azdev extension remove oracle-database — removes oracle-database (no index invalidation)
4. azdev extension add aks-preview — installs aks-preview (no index invalidation)
5. azdev test aks-preview — az cloud show runs again, but commandIndex.json already exists with valid version (2.84.0) and cloud profile (latest), so the stale index is reused
6. Each scenario test calls self.cmd('aks create ...') → DummyCli.invoke() → MainCommandsLoader.load_command_table() → command index maps aks to only ['azure.cli.command_modules.acs'] → aks-preview extension is never loaded → core module's aks_create runs with the GA SDK (azure-mgmt-containerservice, api-version=2026-01-01) instead of the preview SDK (api-version=2026-01-02-preview) → VCR cassette query matcher fails → 262 tests fail

Why This Is Non-Deterministic
ALL_TESTS is built by iterating os.listdir(SRC_PATH), which returns entries in arbitrary filesystem order. The order can differ between runs/environments:

• When aks-preview happens to be listed first: it gets tested before any index exists → index is created WITH the extension → tests pass
• When another extension is listed first: index is created WITHOUT aks-preview → tests fail

Related command

azdev extension add/remove

Errors

The integration tests queued for various Python versions on the same PR (for example, #9665) are showing inconsistent results; some tests failed while others passed.

FAILED src/aks-preview/azext_aks_preview/tests/latest/test_aks_safeguards.py::AksSafeguardsScenario::test_aks_deployment_safeguards_basic
FAILED src/aks-preview/azext_aks_preview/tests/latest/test_aks_safeguards.py::AksSafeguardsScenario::test_aks_deployment_safeguards_with_pss
== 262 failed, 693 passed, 86 skipped, 6 subtests passed in 412.13s (0:06:52) ==

https://dev.azure.com/azclitools/public/_build/results?buildId=304552&view=logs&j=edd23f8e-0483-53ea-dfe4-85f031ec115a&t=758d86e6-87e1-58dd-c45e-4b2170f268bc&l=65188

[gw0] [ 99%] PASSED src/aks-preview/azext_aks_preview/tests/latest/test_vm_skus.py::TestAksIsVmSkuAvailable::test_zone_restriction_ignored_when_zone_flag_false 
src/aks-preview/azext_aks_preview/tests/latest/test_vm_skus.py::TestAksIsVmSkuAvailable::test_zone_restriction_partial_zones_restricted_returns_true 
[gw0] [100%] PASSED src/aks-preview/azext_aks_preview/tests/latest/test_vm_skus.py::TestAksIsVmSkuAvailable::test_zone_restriction_partial_zones_restricted_returns_true 

- generated xml file: /home/cloudtest/.azdev/env_config/mnt/vss/_work/1/s/env/test_results.xml -
======== 955 passed, 86 skipped, 6 subtests passed in 412.58s (0:06:52) ========

https://dev.azure.com/azclitools/public/_build/results?buildId=304552&view=logs&j=85692d73-7fd1-54cf-e8a2-b651dc664eb4&t=5d21126a-3fd1-538a-4d62-56dc95b84a7a&l=4609

Issue script & Debug output

N/A

Expected behavior

The integration tests queued for various Python versions on the same PR (for example, #9665) should have consistent results.

Environment Summary

N/A

Additional context

No response