feat(sdk): expose retained Windows query process handles

[Vineeth Sai Narajala (vineethsai7)]

Rust SDK embedders need to query and wait on the exact Windows workload process already retained by MXC. The current public process API exposes an integer PID, which requires another lookup for those operations. This adds MxcProcess::duplicate_query_process_handle() and a default SandboxProcess method returning Unsupported.

BaseContainer duplicates its retained process handle with PROCESS_QUERY_LIMITED_INFORMATION | SYNCHRONIZE, returning a non-inheritable OwnedHandle. The caller owns the duplicate while MXC retains process lifecycle and cleanup responsibility. Telemetry, warning and DACL wrappers forward the operation. Other backends retain the unsupported default. The API uses the retained process object throughout.

Refs #1521. This draft proposes the API shape for maintainer feedback; the initial implementation covers BaseContainer.

Validation: Windows SDK build and five selected tests passed against these exact five changed source files. Tests cover the unsupported default, forwarding through all three wrappers, operation after stdio transfer, and a query/wait duplicate that survives closure of its source duplicate and has inheritance disabled. The native unit queries the current test process; it creates no contained workload. The validation workflow requires the exact five passing test names and is confined to a separate contributor branch, outside this PR.

rustfmt and git diff --check passed. Full upstream CI and maintainer review remain pending.

Microsoft Reviewers: Open in CodeFlow

[Copilot]

🟡 Changes recommended

Native failure diagnostics must be preserved, and regression coverage should verify the absence of broader handle rights.

2 open issues

• Preserve native DuplicateHandle errors · New
• Verify duplicated handles have query-only access · New

What changed in this PR

Adds Windows-only Rust SDK access to an owned query-and-wait handle for the retained workload process, addressing #1521 without reopening its PID.

Changes:

• Implements restricted, non-inheritable handle duplication for BaseContainer.
• Forwards the operation through process wrappers; other backends default to unsupported.
• Adds forwarding, ownership, inheritance, and wait tests.

File	Description
src/​mxc-sdk/​src/​sandbox.rs	Exposes the public method and tests stdio independence.
src/​mxc-sdk/​src/​core/​mxc_engine/​mod.rs	Adds telemetry and warning wrapper forwarding.
src/​mxc-sdk/​src/​core/​mxc_common/​sandbox_process.rs	Defines the trait method and unsupported default.
src/​mxc-sdk/​src/​backends/​process_container/​common/​dispatcher.rs	Adds DACL wrapper forwarding and coverage.
src/​mxc-sdk/​src/​backends/​process_container/​common/​base_container_runner.rs	Implements handle duplication and native tests.

_{Review effort: Balanced}

[Vineeth Sai Narajala (vineethsai7)]

@microsoft-github-policy-service agree

[Copilot]

🔵 Needs a closer look

The public API addition needs the required SDK README and versioned Rust reference updates.

No open issues 🎉

1 previously missed issue

In code that hasn't changed since last review

Document MxcProcess operation in Rust API references

src/​mxc-sdk/​src/​sandbox.rs:287

The maintained MxcProcess method list in docs/api-reference/rust/v1/types.md:313–328 omits this operation, and src/mxc-sdk/README.md does not describe it. Please update both alongside the public API, documenting its Windows-only signature, current BaseContainer support, Unsupported behavior elsewhere, restricted access rights, and caller ownership without transferring sandbox cleanup responsibility. Also note the intentional Rust-only availability relative to .NET and Node.

2 resolved since last review

• Verify duplicated handles have query-only access
• Preserve native DuplicateHandle errors

_{Review effort: Balanced}

[Vineeth Sai Narajala (vineethsai7)]

Addressed both review points in commit 46c3beef: DuplicateHandle failures now preserve the underlying Win32 error (and retain the HRESULT for other facilities), and the inert current-process test uses NtQueryObject to verify the duplicated handle has exactly query-limited-information and synchronize rights.

The separate fork-only validation run compiled the SDK with locked dependencies and passed all five fixed query/forwarding unit tests (3 + 1 + 1, zero failures). It did not run a sandbox or child workload, and its validation workflow is excluded from this PR. The PR’s CLA check is passing.

[Copilot]

🔵 Needs a closer look

The draft native-handle API needs maintainer sign-off and upstream Windows validation beyond the reported selected tests.

No open issues 🎉

_{Review effort: Balanced}