Python: Add CreateConversationExecutor, fix input routing, remove unused handler layer

[Evan Mattson (moonbox3)]

Motivation and Context

• Adds CreateConversationExecutor to the graph-based executor system, fixing Python: [Bug]: Declarative: Missing CreateConversation implementation #4129
• Fixes System.LastMessage.Text not being populated from workflow string input, so YAML expressions like =System.LastMessage.Text see the user's message
• Fixes runner convergence for looping workflows by threading max_iterations through WorkflowFactory / DeclarativeWorkflowBuilder and supporting a maxTurns YAML field
• Fixes DeepResearch.yaml: adds maxTurns: 500, sets autoSend: false on ManagerAgent to suppress raw JSON output
• Fixes deep_research/main.py: restores shared YAML path, adds newlines between output events
• Removes the entire dead action handler layer (6 source files, 3 test files) confirmed unused in Python: remove unnecessary declarative workflows Action Handlers #3904
• System.ConversationId was hardcoded to "default" in Python declarative workflows, so YAML expressions like conversationId: =System.ConversationId routed messages to System.conversations.default.messages instead of a properly scoped conversation. Now initialize() generates a UUID and seeds a matching System.conversations entry, matching the .NET behavior.

Supersedes #4065

This branch builds on sample-fixes-8 (#4065) and keeps all of its executor fixes. It supersedes #4065 because that PR worked around missing executors by using a simplified local workflow.yaml; this PR fixes the root causes instead.

Description

• Fixes Python: [Bug]: Declarative: Missing CreateConversation implementation #4129
• Closes Python: remove unnecessary declarative workflows Action Handlers #3904

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

This PR enhances the Python declarative (graph-based) workflow execution path by adding missing executors (notably CreateConversation), improving input/state routing for PowerFx expressions, and removing an unused legacy “action handler” execution layer.

Changes:

• Add CreateConversationExecutor, improve dynamic agent name expression evaluation, and adjust branch-exit/terminator handling to prevent incorrect edge wiring.
• Thread runner iteration limits via WorkflowFactory/DeclarativeWorkflowBuilder, supporting a YAML maxTurns field; update DeepResearch sample accordingly.
• Remove the unused legacy handler layer and associated tests; update samples/tests to use the executor-based system.

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
workflow-samples/DeepResearch.yaml	Adds maxTurns: 500 and sets autoSend: false to improve looping convergence and suppress raw JSON output.
python/samples/03-workflows/declarative/human_in_loop/main.py	Updates streaming output handling to align with executor-based output payloads.
python/samples/03-workflows/declarative/deep_research/main.py	Adjusts streaming print formatting (adds newlines between output events).
python/samples/02-agents/context_providers/redis/redis_conversation.py	Removes an unused import.
python/samples/01-get-started/06_host_your_agent.py	Adds whitespace (formatting-only).
python/packages/declarative/tests/test_workflow_samples_integration.py	Switches coverage check from handlers to ALL_ACTION_EXECUTORS.
python/packages/declarative/tests/test_workflow_handlers.py	Removes tests for the deleted handler layer.
python/packages/declarative/tests/test_workflow_factory.py	Removes tests tied to the deleted handler-layer ActionContext.
python/packages/declarative/tests/test_graph_coverage.py	Adds tests for expression-based agent name resolution, terminator branch exit handling, and CreateConversationExecutor.
python/packages/declarative/tests/test_external_input.py	Removes tests for the deleted handler-based HITL implementation.
python/packages/declarative/tests/test_additional_handlers.py	Removes tests for the deleted handler layer (conversation/variables/etc.).
python/packages/declarative/agent_framework_declarative/_workflows/_human_input.py	Removes the handler-based HITL implementation module.
python/packages/declarative/agent_framework_declarative/_workflows/_handlers.py	Removes the handler registry/types module.
python/packages/declarative/agent_framework_declarative/_workflows/_factory.py	Adds max_iterations plumbing into graph builder creation.
python/packages/declarative/agent_framework_declarative/_workflows/_executors_control_flow.py	Ensures JoinExecutor initializes state before passing through.
python/packages/declarative/agent_framework_declarative/_workflows/_executors_basic.py	Adds CreateConversationExecutor and registers it in BASIC_ACTION_EXECUTORS.
python/packages/declarative/agent_framework_declarative/_workflows/_executors_agents.py	Supports = PowerFx expressions for agent name fields across schema variants.
python/packages/declarative/agent_framework_declarative/_workflows/_declarative_builder.py	Adds more terminators, threads max_iterations into WorkflowBuilder, and improves _get_branch_exit terminator handling.
python/packages/declarative/agent_framework_declarative/_workflows/_declarative_base.py	Populates System.LastMessage.Text from string (and non-dict) workflow inputs.
python/packages/declarative/agent_framework_declarative/_workflows/_actions_error.py	Removes handler-based error actions module.
python/packages/declarative/agent_framework_declarative/_workflows/_actions_control_flow.py	Removes handler-based control-flow actions module.
python/packages/declarative/agent_framework_declarative/_workflows/_actions_basic.py	Removes handler-based basic actions module.
python/packages/declarative/agent_framework_declarative/_workflows/_actions_agents.py	Removes handler-based agent invocation actions module.
python/packages/declarative/agent_framework_declarative/_workflows/init.py	Updates exports to reflect the executor-only workflow implementation.

[corradopignato]

Hi Evan Mattson (@moonbox3), could you also check System.ConversationId?
It seems that its value always remains _default when we call InvokeAzureAgent.
Is this the intended behavior?

[Mark Wallace (markwallace-microsoft)]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/declarative/agent_framework_declarative/_workflows
_declarative_base.py	385	40	89%	44, 47, 130–131, 134, 212, 226, 240, 251, 268, 403, 431, 514–516, 518–520, 522, 525, 532, 558, 582–586, 588–596, 617–618, 620–621
_declarative_builder.py	352	26	92%	148, 180, 187, 244, 335, 357, 367, 418, 420, 428, 443, 479, 482, 508–509, 528–529, 605, 610, 654–656, 680–681, 903, 976
_executors_agents.py	476	86	81%	95–96, 113–115, 156–157, 164, 192, 195–196, 204–205, 215, 226–231, 497, 535–537, 540, 556, 572–576, 600, 605, 695, 701–706, 713, 737–738, 747–749, 798–799, 807, 826, 933–936, 943–944, 953–954, 966–971, 975–976, 978, 983, 985, 989–992, 995, 997–998, 1001, 1009–1011, 1013, 1016–1017, 1019, 1046–1047
_executors_basic.py	294	36	87%	343, 418, 420, 425–427, 440–446, 469, 474–477, 544, 549, 556–558, 562, 565, 569, 571, 576–578, 582, 584, 589–591, 594
_executors_control_flow.py	170	6	96%	81, 89, 152, 342–343, 347
_factory.py	139	60	56%	186, 263–264, 328–330, 338, 340, 343–349, 378, 390–391, 400, 435, 448, 473–476, 495–499, 502–503, 506, 509, 514, 623–624, 626–627, 629–631, 634, 648, 651–656, 659–660, 662, 665, 675–676, 678, 682–683, 685
_state.py	311	172	44%	23, 26, 146, 170, 184, 197, 206–207, 209, 225, 233, 241, 245, 247, 249, 259, 367, 373, 375, 377–381, 385, 403, 405, 408–411, 414–417, 420–422, 424–430, 433–437, 440–444, 447–463, 466–469, 471–474, 476–479, 481–484, 486–493, 496–499, 501–508, 511–514, 516–522, 524–528, 531–532, 535–540, 543–546, 549, 552–557, 560, 571–575, 577–594, 596, 598–599, 601, 617
TOTAL	21208	3085	85%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
4221	240 💤	0 ❌	0 🔥	1m 11s ⏱️

[Evan Mattson (moonbox3)]

Hi Evan Mattson (@moonbox3), could you also check System.ConversationId? It seems that its value always remains _default when we call InvokeAzureAgent. Is this the intended behavior?

Fixed in 19c71d2.