Deprecating AgentApplication ownership of a single channel adapter

[Rodrigo Brandão (rodrigobr-msft)]

This pull request refactors how the bot adapter is managed within AgentApplication to improve flexibility and error handling. The adapter is no longer stored as an internal attribute, and related methods and checks have been updated to access the adapter from the TurnContext directly. Additionally, error handler registration and long-running call management have been updated to align with this change.

Adapter Management Refactor

• Removed the internal _adapter attribute and the adapter property from AgentApplication, shifting adapter access to use context.adapter instead. This simplifies the class and avoids potential stale references. [1] [2]
• Updated checks and error messages in the constructor to only require bot_app_id when long_running_messages is enabled, removing the previous check for an adapter.

Error Handling Improvements

• Changed error handler registration to append handlers to a new _turn_error_handlers list instead of setting them directly on an internal adapter, allowing for multiple error handlers and decoupling error handling from the adapter. [1] [2]

Long-Running Call and Conversation Replay

• Updated long-running call logic and conversation replay to use context.adapter for continuing conversations, ensuring the correct adapter instance is used per turn. [1] [2]

[Copilot]

Copilot review overview

🟡 Changes recommended

Removing the adapter property leaves multiple samples and generated entry points failing with AttributeError.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 2 · 2

Open (4)

• Preserve positional arguments in the public from_app factory · New
• Complete adapter removal or explicitly deprecate the obsolete option · New
• Update diagnostic to report only missing bot_app_id · New
• Test that continuation uses the current turn's adapter · New

What changed in this PR

Refactors AgentApplication to use each turn’s adapter and updates testing utilities accordingly.

Changes:

• Moves adapter-dependent operations to TurnContext.adapter.
• Supports multiple application error handlers.
• Adds configurable adapter handling to AiohttpScenario.from_app.

File	Description
tests/​hosting_core/​app/​test_agent_application.py	Tests error-handler behavior.
libraries/​.../​app/​agent_application.py	Refactors adapter and error handling.
dev/​.../​tests/​test_aiohttp_scenario.py	Tests existing-app scenario construction.
dev/​.../​README.md	Documents adapter selection.
dev/​.../​aiohttp_scenario.py	Adds optional scenario adapter.
dev/​.../​docs/​README.md	Adds usage guidance.
dev/​.../​docs/​API.md	Documents the updated API.

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[Copilot]

Copilot review overview

🟡 Changes recommended

The long-running-message path currently calls incompatible adapter APIs and fails before executing its callback.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 1 · 3

Open (4)

• Fix long-running continuation call for supported adapter contracts · New
• Set deprecation warning stacklevel to 2 · New
• Format changed signature to satisfy Black line length · New
• Keep trailing comma to preserve Black formatting · New

Resolved since last review (4)

• Complete adapter removal or explicitly deprecate the obsolete option
• Preserve positional arguments in the public from_app factory
• Test that continuation uses the current turn's adapter
• Update diagnostic to report only missing bot_app_id

[Copilot]

Copilot review overview

🟡 Changes recommended

Long-running calls use an incompatible adapter signature, and the cards sample references an undefined adapter name.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 2

Open (2)

• Fix incompatible continue_conversation arguments · New
• Use the defined lowercase adapter variable · New

Resolved since last review (4)

• Fix long-running continuation call for supported adapter contracts
• Keep trailing comma to preserve Black formatting
• Format changed signature to satisfy Black line length
• Set deprecation warning stacklevel to 2

[Copilot]

Copilot review overview

🟡 Changes recommended

Long-running messages currently call the adapter with an invalid keyword and omit the required callback.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 1

Open (1)

• Use the adapter's correct signature for long-running turns · New

Resolved since last review (2)

• Use the defined lowercase adapter variable
• Fix incompatible continue_conversation arguments

[Copilot]

Copilot review overview

🔵 Needs a closer look

Key continuation paths lack direct coverage, and validation errors still describe a removed adapter requirement.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Use the adapter's correct signature for long-running turns