GeezerVison

Backport of #27373 to release/v7.6.7

Triggered by Aditya Patwardhan (@adityapatwardhan) on behalf of Justin Chung (@jshigetomi)

Original CL Label: CL-Engine

/cc @PowerShell/powershell-maintainers

Impact

REQUIRED: Choose either Tooling Impact or Customer Impact (or both). At least one checkbox must be selected.

Tooling Impact

• Required tooling change
• Optional tooling change (include reasoning)

Customer Impact

• Customer reported
• Found internally

Fixes #27370, where PowerShell can fail during startup when the per-user powershell.config.json is unreadable because a cloud file provider such as OneDrive is not running, access is denied, JSON is malformed, or a value has the wrong shape. Expected behavior is a warning and fallback to default current-user settings; system-wide configuration errors remain hard failures.

Regression

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• Yes
• No

This is not a regression.

Testing

The original PR added xUnit coverage for malformed and unreadable current-user configuration files, type-mismatched values, fallback-to-default behavior, warning emission to stderr, and continued strict failure for the all-users configuration. The backport cherry-picked cleanly onto the latest upstream release/v7.6.7; the worktree is clean, the branch is exactly one commit ahead of the target, and git diff --check passed. CI will provide release-branch build and test validation.

Risk

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• High
• Medium
• Low

Medium risk because this changes early-startup configuration handling in the engine. The change is scoped to current-user configuration failures, preserves fail-closed behavior for the security-relevant all-users configuration, and includes focused xUnit coverage for both fallback paths and warning output.