Switch .NET to exact JSON FFI ingress by MGudgin · Pull Request #1351 · microsoft/mxc

Gudge (MGudgin) · 2026-09-30T16:43:48Z

This PR maps V1 .NET execution and request probing to the SDK-owned exact
1.0.0 JSON contract. It generates C# wire types from the registered Rust
contract and uses one writer for all native entry points, preserving Native
AOT through source-generated serialization.

Details

Generate closed C# contract types and drift checks, preserving unsigned
numeric bounds and required nullable fields under null-omitting options.
Move Run, Spawn, and Probe onto exact JSON FFI with shared source-generated
serialization and actionable errors for unsupported policy.
Preserve environment order and caller IDs; reject invalid keys, enum
values, and unsupported stable experimental authorization before native.
Correct lifecycle guidance and keep managed API parity checks precise for
attribute ordering, ignored fields, and sandbox-id prefix dispatch.

Tests

Cargo format, compiler, clippy and schema emitter tests passed.
Contract codegen, .NET API parity and exact fixture gates passed.
dotnet test --solution Microsoft.Mxc.Sdk.slnx: 329 passed, 29 skipped.
XML docs and reflection-disabled win-x64 Native AOT publish/run passed.
Native Linux/macOS and elevated live-host tests were not run locally.

Microsoft Reviewers: Open in CodeFlow

azure-pipelines · 2026-09-30T16:43:59Z

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Copilot

Copilot review overview

🟡 Changes recommended

Exact-wire numeric and environment mappings are incorrect, and two public API paths provide misleading experimental behavior.

Review effort: Balanced
Findings: 1 · 2 · 1

Open (4)

Parse unsigned schema minima without lossy Int64 conversion · New
Preserve caller order for environment variables · New
Reject or deprecate silently ignored Experimental requests · New
Document the actual supported Windows Sandbox request path · New

What changed in this PR

Moves the .NET V1 SDK to exact 1.0.0 JSON FFI ingress.

Changes:

Adds generated C# wire types and drift validation.
Maps public .NET policies to exact JSON requests.
Routes one-shot APIs through JSON FFI and expands conformance tests.

File	Description
`src/tools/mxc_schema_gen/tests/cli.rs`	Tests C# generation.
`src/tools/mxc_schema_gen/src/main.rs`	Adds the `csharp` command.
`src/core/mxc_schema_support/src/lib.rs`	Exposes C# emission.
`src/core/mxc_schema_support/src/cs_emit.rs`	Implements the C# emitter.
`src/core/mxc_config_contract/src/registry.rs`	Registers C# artifact paths.
`sdk/dotnet/Microsoft.Mxc.Sdk/V1/MxcSandbox.cs`	Uses JSON FFI entry points.
`sdk/dotnet/Microsoft.Mxc.Sdk/V1/MxcLifecycle.cs`	Rejects stable `wsb:` lifecycle IDs.
`sdk/dotnet/Microsoft.Mxc.Sdk/V1/ExactOneShotRequestWriter.cs`	Maps V1 requests to exact wire types.
`sdk/dotnet/Microsoft.Mxc.Sdk/Generated/MxcConfigV1_0_0.g.cs`	Adds generated 1.0.0 models.
`sdk/dotnet/Microsoft.Mxc.Sdk.Tests/V1/SandboxPolicyTests.cs`	Updates exact-contract assertions.
`sdk/dotnet/Microsoft.Mxc.Sdk.Tests/V1/MxcSandboxTests.cs`	Updates one-shot serialization tests.
`sdk/dotnet/Microsoft.Mxc.Sdk.Tests/V1/MxcLifecycleTests.cs`	Tests `wsb:` rejection.
`sdk/dotnet/Microsoft.Mxc.Sdk.Tests/V1/ExactOneShotRequestWriterTests.cs`	Adds writer conformance tests.
`sdk/dotnet/Microsoft.Mxc.Sdk.Tests/Microsoft.Mxc.Sdk.Tests.csproj`	Embeds SDK-v1 fixtures.
`sdk/dotnet/Microsoft.Mxc.Sdk.Tests/JsonAssert.cs`	Generalizes JSON comparison.
`scripts/versioning/check-contract-codegen.js`	Adds C# drift checks.
`scripts/check-dotnet-bindings-codegen.js`	Marks JSON exports as consumed.
`scripts/check-dotnet-api-parity.js`	Checks against the exact contract.
`docs/schema-codegen.md`	Documents C# generation.

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Copilot

Copilot review overview

🟡 Changes recommended

The generated wire model narrows valid u64 values, while request mapping also changes supplied IDs and environment ordering.

Review effort: Balanced
Findings: 1 · 3 · 1

Open (5)

Parse unsigned schema minima without lossy Int64 conversion
Empty container names are incorrectly replaced with generated IDs · New
Reject or deprecate silently ignored Experimental requests
Preserve caller order for environment variables
Document the actual supported Windows Sandbox request path

Copilot

Copilot review overview

🟡 Changes recommended

Valid ulong memory values regress, environment validation is weakened, and the public experimental opt-in becomes silently ineffective.

Review effort: Balanced
Findings: 2 · 3 · 1

Open (6)

Projection drops key validation and changes caller entry order · New
Parse unsigned schema minima without lossy Int64 conversion
Empty container names are incorrectly replaced with generated IDs
Reject or deprecate silently ignored Experimental requests
Preserve caller order for environment variables
Document the actual supported Windows Sandbox request path

Copilot

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Copilot couldn't run its full agentic review because it didn't start before the timeout. Make sure your repository has a runner available, or add a copilot-code-review.yml file specifying one with the runs-on attribute. See the docs for more details.

Copilot review overview

Review effort: Lite
Findings: 1 · 3

Open (4)

Required-but-nullable schema properties (e.g., via anyOf: [T, null] while still listed in… · New
This regex-based field extractor is brittle: it only matches when [JsonPropertyName(...)] appears… · New
This now scans the entire MxcLifecycle.cs source for \"...\" => StateAwareContainment.X… · New
This always assigns PreservePolicy a non-null boolean, so it will serialize as `preservePolicy:… · New

Resolved since last review (6)

Projection drops key validation and changes caller entry order
Parse unsigned schema minima without lossy Int64 conversion
Empty container names are incorrectly replaced with generated IDs
Reject or deprecate silently ignored Experimental requests
Preserve caller order for environment variables
Document the actual supported Windows Sandbox request path

This PR maps V1 .NET execution and request probing to the SDK-owned exact 1.0.0 JSON contract. It generates C# wire types from the registered Rust contract and uses one writer for all native entry points, preserving Native AOT through source-generated serialization. Details * Generate closed C# contract types and drift checks, preserving unsigned numeric bounds and required nullable fields under null-omitting options. * Move Run, Spawn, and Probe onto exact JSON FFI with shared source-generated serialization and actionable errors for unsupported policy. * Preserve environment order and caller IDs; reject invalid keys, enum values, and unsupported stable experimental authorization before native. * Correct lifecycle guidance and keep managed API parity checks precise for attribute ordering, ignored fields, and sandbox-id prefix dispatch. Tests * Cargo format, compiler, clippy and schema emitter tests passed. * Contract codegen, .NET API parity and exact fixture gates passed. * dotnet test --solution Microsoft.Mxc.Sdk.slnx: 329 passed, 29 skipped. * XML docs and reflection-disabled win-x64 Native AOT publish/run passed. * Native Linux/macOS and elevated live-host tests were not run locally. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 30c4f940-9c8e-4d3e-89ff-b1776045bb1c Generated-with: gpt-6-sol

Copilot

Warning

Copilot couldn't run its full agentic review because it didn't start before the timeout. Make sure your repository has a runner available, or add a copilot-code-review.yml file specifying one with the runs-on attribute. See the docs for more details.

Copilot review overview

Review effort: Lite
Findings: 1 · 4 · 1

Open (6)

Required-but-nullable schema properties (e.g., via anyOf: [T, null] while still listed in…
Minting containerId from only 4 random bytes (32 bits) makes collisions plausible in… · New
inheritDefaultEnv can currently be emitted even when env is omitted (i.e., process.env is… · New
This now scans the entire MxcLifecycle.cs source for \"...\" => StateAwareContainment.X…
This regex-based field extractor is brittle: it only matches when [JsonPropertyName(...)] appears…
camelCase appears to be unused after the refactor to schema-based comparisons and the updated… · New

Resolved since last review (1)

This always assigns PreservePolicy a non-null boolean, so it will serialize as `preservePolicy:…

+  if (cwd !== undefined) process.cwd = cwd;
+  const env = environment(config, options);
+  if (env !== undefined) process.env = env;
+  if (inheritDefaultEnv(config, options)) process.inheritDefaultEnv = true;


Copilot

Copilot review overview

🟡 Changes recommended

Malformed C# artifact metadata can silently bypass drift validation, and migration documentation remains stale.

Review effort: Balanced
Findings: 2 · 1

Open (3)

Reject missing or empty csharpPath metadata · New
inheritDefaultEnv can currently be emitted even when env is omitted (i.e., process.env is…
Update stale documentation for exact request serialization · New

Resolved since last review (5)

Required-but-nullable schema properties (e.g., via anyOf: [T, null] while still listed in…
Minting containerId from only 4 random bytes (32 bits) makes collisions plausible in…
This now scans the entire MxcLifecycle.cs source for \"...\" => StateAwareContainment.X…
This regex-based field extractor is brittle: it only matches when [JsonPropertyName(...)] appears…
camelCase appears to be unused after the refactor to schema-based comparisons and the updated…

+    const hasCsharpPath =
+      typeof contract.csharpPath === "string" && contract.csharpPath.length > 0;


    {
        ArgumentNullException.ThrowIfNull(request);
-        return MxcJson.Serialize(PrepareRequest(request), MxcJson.Options);
+        return ExactOneShotRequestWriter.Serialize(request);


Gudge (MGudgin) mentioned this pull request Sep 30, 2026

Remove the binding request FFI exports #1352

Merged

Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch from 0492605 to 53f0bfa Compare September 30, 2026 17:18

Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch 2 times, most recently from eafb96a to 8d1b835 Compare September 30, 2026 17:32

Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch from 8d1b835 to 83eb313 Compare September 30, 2026 20:29

Gudge (MGudgin) changed the base branch from user/gudge/rust_ffi_json_ingress to user/gudge/node-json-ffi September 30, 2026 20:29

Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch from 83eb313 to eaffaf6 Compare September 30, 2026 20:31

Gudge (MGudgin) added this pull request to stack #1356 September 30, 2026 21:26

Gudge (MGudgin) marked this pull request as ready for review September 30, 2026 21:27

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Comment thread src/core/mxc_schema_support/src/cs_emit.rs Outdated

Comment thread sdk/dotnet/Microsoft.Mxc.Sdk/V1/ExactOneShotRequestWriter.cs

Comment thread sdk/dotnet/Microsoft.Mxc.Sdk/V1/MxcSandbox.cs

Comment thread sdk/dotnet/Microsoft.Mxc.Sdk/V1/MxcLifecycle.cs

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Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch from 9fe4ac0 to 885b720 Compare September 30, 2026 21:40

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Comment thread sdk/dotnet/Microsoft.Mxc.Sdk/V1/ExactOneShotRequestWriter.cs

Gudge (MGudgin) mentioned this pull request Oct 2, 2026

Make exact versioned JSON the only FFI configuration ingress #1349

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Copilot AI balanced review requested due to automatic review settings October 2, 2026 22:13

Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch from 885b720 to 4bb99c7 Compare October 2, 2026 22:13

Gudge (MGudgin) mentioned this pull request Oct 2, 2026

Switch Node to exact JSON FFI ingress #1350

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Comment thread src/core/mxc_schema_support/src/cs_emit.rs

Comment thread scripts/check-dotnet-api-parity.js Outdated

Comment thread scripts/check-dotnet-api-parity.js Outdated

Comment thread sdk/dotnet/Microsoft.Mxc.Sdk/V1/ExactOneShotRequestWriter.cs

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Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch from 4bb99c7 to 44e58a0 Compare October 2, 2026 23:18

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Gudge (MGudgin) force-pushed the user/gudge/dotnet-json-ffi branch from 44e58a0 to 260bd1c Compare October 2, 2026 23:36

Branden Bonaby (bbonaby) approved these changes Oct 2, 2026

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Gudge (MGudgin) merged commit 232ab9e into main Oct 2, 2026
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Switch .NET to exact JSON FFI ingress - #1351

Switch .NET to exact JSON FFI ingress#1351
Gudge (MGudgin) merged 1 commit into
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Gudge (MGudgin) commented Sep 30, 2026 •

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		const hasCsharpPath =
		typeof contract.csharpPath === "string" && contract.csharpPath.length > 0;

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Gudge (MGudgin) commented Sep 30, 2026 •

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