.NET: Preserve table state across declarative EditTable operations

[peibekwe]

Motivation & Context

Keeps itemsVariable as a table after Remove, Clear, TakeFirst, and TakeLast so later edits continue to work. Results use resultVariable, and checkpointed tables remain downgrade-compatible and editable after resume.

Fixes #7351

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

Pull request overview

This PR updates the .NET declarative EditTable / EditTableV2 executors so table-edit operations (Remove, Clear, TakeFirst, TakeLast) preserve the original table variable as a TableValue, enabling subsequent table edits and improving checkpoint/resume compatibility. It also expands unit test coverage to validate table preservation and portable (checkpoint) round-trips.

Changes:

• Update EditTableExecutor and EditTableV2Executor to keep itemsVariable bound to a (mutated) table after Clear/Remove/TakeFirst/TakeLast, with taken items routed via ResultVariable.
• Add/adjust unit tests to validate preserved table schema/shape and editability after portable restore and checkpoint/resume.
• Refine portable table restoration logic for legacy shapes and add tests for legacy portability expectations.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/EditTableExecutor.cs	Preserves table variables across edits and routes operation results via ResultVariable.
dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/EditTableV2Executor.cs	Aligns V2 executor behavior with table preservation and supports ResultVariable for take operations.
dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Extensions/PortableValueExtensions.cs	Updates portable → formula table reconstruction to better preserve table shapes/types.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/ObjectModel/EditTableExecutorTest.cs	Adds/updates tests for table preservation, portable restore, and checkpoint/resume scenarios.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/ObjectModel/EditTableV2ExecutorTest.cs	Adds/updates V2 tests ensuring operations preserve table state and set results as expected.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/Extensions/PortableValueExtensionsTests.cs	Adds tests asserting legacy portable shapes and append behavior after restoration.

[github-actions]

Automated Code Review

Reviewers: 5 | Confidence: 89%

✓ Correctness

The PR correctly preserves table state across EditTable operations (Remove, Clear, TakeFirst, TakeLast) by keeping the table in itemsVariable and writing taken/removed results to resultVariable. The PortableValueExtensions changes ensure restored tables are mutable (support AppendAsync) by materializing records into arrays. The special-case handling for empty+schemaless tables in the Add operation gracefully handles the schema loss that occurs during checkpoint round-trips of empty tables. AssignAsync safely handles null PropertyPath by short-circuiting. The changes are well-covered by comprehensive tests including checkpoint/restore scenarios.

✓ Security Reliability

The PR preserves table state across declarative EditTable operations by keeping itemsVariable as a table after Remove, Clear, TakeFirst, and TakeLast, and routing extracted values to resultVariable. The changes are well-structured and well-tested. AssignAsync safely handles null PropertyPath? via early return (DeclarativeActionExecutor.cs:129-131), so the nullable this.Model.ResultVariable?.Path calls are safe. The empty-table schema-loss during checkpoint serialization (via RecordType.Empty() in ToTable for 0-length arrays) is correctly compensated in the Add path by inferring schema from the new value. No security, injection, resource leak, or reliability issues found.

✓ Test Coverage

Test coverage for this PR is comprehensive. All key behavioral changes — table preservation across Remove/Clear/TakeFirst/TakeLast, resultVariable assignment, checkpoint/restore roundtrips, and legacy table mutability — are well-covered with meaningful assertions. Both V1 (EditTableExecutor) and V2 (EditTableV2Executor) have thorough test suites, with composite operation tests (e.g., clear→restore→add, takeFirst→add) validating the core fix. Two minor symmetric gaps exist but are low risk.

✓ Failure Modes

The PR correctly preserves table state across EditTable operations by keeping itemsVariable as a table after Remove, Clear, TakeFirst, and TakeLast, routing extracted/result values to resultVariable instead. The PortableValueExtensions.ToTable change (.ToArray()) ensures restored tables are mutable and support AppendAsync. The AssignAsync base method safely handles null ResultVariable?.Path by returning early. The empty-schema-table Add path correctly detects schema-less tables via !recordType.FieldNames.Any() && !tableValue.Rows.Any() and rebuilds from the record value. Both V1 and V2 executors are updated consistently. No concrete new failure modes were identified.

✓ Design Approach

The table-preservation approach looks sound for record tables and most primitive tables, but it still leaves a compatibility gap for date-only primitive tables restored from checkpoints. The new PortableValue[] -> TableValue path infers DateTime for restored date-like columns even though the same portable scalar path round-trips midnight DateTime values as FormulaType.Date, so the PR does not fully satisfy its stated downgrade/editability goal for that input.

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Automated review by peibekwe's agents

[github-actions]

Automated Code Review

Reviewers: 5 | Confidence: 90% | Result: All clear

Reviewed: Correctness, Security Reliability, Test Coverage, Failure Modes, Design Approach

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Automated review by peibekwe's agents