[Dineshsuriya D (droideronline)]

Motivation & Context

Orchestration builders that enabled checkpointing inherited generated WorkflowBuilder-<uuid> names because they did not pass a workflow name to the core builder. This made checkpoint grouping and discovery inconsistent across orchestration patterns. Stable defaults are useful when multiple independent workflow instances share the same workflow definition.

Description & Review Guide

• What are the major changes?
  • Add stable default workflow-name constants for GroupChat, Sequential, Concurrent, Handoff, and Magentic.
  • Forward each builder's resolved name to the underlying WorkflowBuilder.
  • Preserve optional custom names and keep checkpoint IDs responsible for per-instance uniqueness.
• What is the impact of these changes?
  • New workflows use stable orchestration-specific names instead of generated builder names.
  • Existing builder call sites remain compatible; custom names continue to work.
• What do you want reviewers to focus on?
  • Consistency of the default names and the distinction between workflow definition names and checkpoint instance IDs.

Related Issue

Fixes #8383

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) — a workflow keeps the label and title prefix in sync automatically.

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[Dineshsuriya D (droideronline)]

Stable orchestration names make checkpoint grouping predictable, but get_latest(workflow_name=...) can select a checkpoint from a different workflow instance when multiple conversations share the same name. Should stable names be treated strictly as workflow-definition keys, with applications persisting the exact checkpoint_id per conversation, or should checkpoint lookup support an additional conversation/session identifier?