[Bug] UserAuthorization refresh sends composite Copilot channel to GetToken #456

Summary

UserAuthorization normalizes the initial M365 Copilot Web sign-in request to the base msteams channel, but its later refresh path sends the raw composite msteams:COPILOT channel to Bot Framework GetToken.

The initial route auth gate succeeds, then Authorization.get_token() / exchange_token() refreshes through the raw channel partition and receives HTTP 404. Teams works because its incoming channel is already msteams; the failure is specific to M365 Copilot's composite channel.

Environment

• microsoft-agents-hosting-core==1.1.0
• Also reproduced from current main at e24623e
• Also present in the published 1.2.0.dev9 wheel
• UserAuthorization with an Azure Bot OAuth connection
• Custom engine agent invoked from M365 Copilot Web

Reproduction

1. Configure a normal UserAuthorization handler backed by an Azure Bot OAuth connection.
2. Register a message route with that handler in auth_handlers.
3. Expose the agent in M365 Copilot Web so inbound activities use channelId=msteams:COPILOT.
4. Complete silent SSO or interactive sign-in.
5. Read or exchange the authenticated token in the route with Authorization.get_token() or Authorization.exchange_token().

Observed token-service sequence:

GetTokenOrSignInResource(channelId=msteams)          -> 200
GetToken(channelId=msteams:COPILOT)                 -> 404

The first request uses the base channel because #392 calls get_conversation_reference(force_base_channel=True) in _OAuthFlow.begin_flow(). The refresh request does not.

Root cause

The remaining path is:

Authorization.exchange_token()
  -> _UserAuthorization.get_refreshed_token()
  -> _UserAuthorization._load_flow()
       flow_state.channel_id = context.activity.channel_id
  -> _OAuthFlow.__init__()
       self._channel_id = flow_state.channel_id
  -> _OAuthFlow.get_user_token()
       UserToken.get_token(channel_id=self._channel_id)

_UserAuthorization._load_flow() records the raw activity channel in _FlowState, and _OAuthFlow reuses it for Bot Framework token operations. For Copilot Web this remains msteams:COPILOT.

Expected behavior

Bot Framework token operations should use the base msteams channel while OAuth flow storage, continuation activities, telemetry, and replies retain the original msteams:COPILOT channel.

The activity itself must not be mutated, because outbound streaming and replies need the original Copilot conversation reference.

Impact

A user can be signed in successfully at the route gate, but the handler's subsequent token read/refresh fails. The message turn then raises and M365 Copilot displays a generic failure instead of invoking the agent. Repeated attempts continue to fail because the successful base-channel token is queried through the wrong composite partition.

Proposed fix

Normalize only _OAuthFlow's operational token channel to the base segment while preserving _FlowState.channel_id unchanged:

self._channel_id = self._flow_state.channel_id.split(":", 1)[0]

This keeps flow storage and continuation semantics surface-specific while making GetToken, token exchange, and sign-out consistent with the base-channel behavior already added to begin_flow() by #392.

A regression test should assert both halves:

• UserToken.get_token(..., channel_id="msteams")
• flow.flow_state.channel_id == "msteams:COPILOT"

Validation

An application-level implementation of the same boundary was deployed and verified with consecutive M365 Copilot Web turns:

message_received channel=msteams:COPILOT
 token exchange succeeded
 agent invocation completed successfully
 streamed reply finalized on channel=msteams:COPILOT

The previous GetToken 404 / failed-turn signature disappeared. No tenant IDs, application IDs, tokens, internal URLs, or conversation identifiers are included here.

Related work

• #391 described the composite-channel OAuth requirement.
• #392 fixed the initial GetTokenOrSignInResource and encoded-state path.
• microsoft/Agents-for-net#827 tracks the corresponding composite-channel behavior in .NET.