[Naveen Chatlapalli (1aifanatic)]

Motivation & Context

=If(IsBlank(inputs.name), "World", inputs.name) never applies its default when the caller omits name, so the simple_workflow sample prints Hello, ! for workflow.run({}). PowerFx fails to compile inputs.name when the inputs record has no such field, and DeclarativeWorkflowState.eval() returns None for the whole expression. Details and an input matrix are in #9729.

Description & Review Guide

• What are the major changes?
  • Evaluate formulas against the original symbols first. If PowerFx reports an unrecognized name, use its diagnostic spans to find missing input references and retry once with those fields bound to blank.
  • Support inputs and Workflow.Inputs, quoted identifiers, comments between tokens, and nested paths. Valid locally scoped references do not add fields to the global input record. Custom inputs namespaces remain independent from Workflow.Inputs.
  • Keep caller-supplied values and workflow state unchanged. If the synthesized bindings cannot compile, or diagnostic locations are unavailable, retain the existing None fallback.
  • Print the outputs of the simple workflow sample's second run with "Alice".
• What is the impact of these changes? Omitted inputs can use IsBlank defaults. Formulas that already evaluate successfully retain their existing behavior.
• What do you want reviewers to focus on? Blank semantics for omitted inputs, preserving independent namespaces and local scopes, and the fallback when missing paths cannot be completed.

Regression coverage includes both aliases, quoted/comment-separated references, literals, custom namespaces, nested paths, and local bindings through With, As, and ForAll. Diagnostic offsets are converted from UTF-16 so preceding non-BMP characters do not shift reference matching. The latest local-scope regressions fail before the fix. All 1,699 declarative tests pass with the .NET runtime; Ruff lint/format and source Pyright checks pass.

Related Issue

Fixes #9729

AI Assistance

• No material AI assistance was used.
• This is an AI-assisted contribution. I reviewed, understood, and verified all submitted content and accept responsibility for it.

AI assistance details: Claude Code helped find the bug by running the declarative samples locally, trace it to DeclarativeWorkflowState.eval(), implement the initial fix and tests, and draft the linked issue. Codex helped address review feedback, reproduce and fix local-scope handling during retries, add regression coverage, run validation, and update this description.

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 links to an agreed issue with no competing open PR, or the Related Issue section documents a trivial-change or repository-automation exception.
• 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.

🤖 Generated with Claude Code

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🟡 Changes recommended

Reference discovery matches literal and comment text while missing valid quoted and whitespace-separated references.

2 open issues

• Recognize quoted and spaced input references · New
• Ignore comments and literals when inferring input bindings · New

What changed in this PR

This PR addresses #9729 by binding omitted workflow inputs as blank during PowerFx evaluation, allowing default expressions to run without modifying workflow state.

Changes:

• Adds evaluation-only blank bindings for references through both input aliases.
• Tests omitted-input defaults and verifies state remains unchanged.
• Prints the custom-name run’s outputs in the simple workflow sample.

File	Description
python/​samples/​03-workflows/​declarative/​simple_workflow/​main.py	Prints outputs from the “Alice” run.
python/​packages/​declarative/​tests/​test_powerfx_yaml_compatibility.py	Adds missing-input regression tests for both aliases.
python/​packages/​declarative/​agent_framework_declarative/​_workflows/​_declarative_base.py	Discovers missing input references and binds evaluation-only blanks.

_{Review effort: Balanced}