[yuyixg]

Two additions to the Twilio ConversationRelay plugin, for agents that need to know how a call ended and whether the caller heard a line in full.

The problems

1. A caller hanging up reaches no hook. ITwilioSessionHook reports the agent hanging up (OnAgentHangUp) and transferring (OnAgentTransferring). When the caller hangs up, the session ends with no hook at all, so an agent can't act on the end of most calls, for example to keep the transcript once the call is over.
2. A cut-in on text spoken after the turn goes unnoticed. Text a tool gives is spoken once the turn is over (GetUnstreamedText). When the caller cuts into it, the history has already kept it whole, and only streamed text gets the cut-off mark. So a flow that reads a line the caller must hear in full, such as a disclaimer they agree to, has to make it uninterruptible.

What this does

• ITwilioSessionHook.OnCallerHangUp (default no-op) fires from the action callback when the session ends with the call completed and no handoff from the agent.
• The session notes text said after a turn, and an interrupt that lands on it. The next turn gets ConversationRelayStates.LastReplyCutOff (twilio_relay_last_reply_cut_off) set to "true", and the state is removed otherwise. The flow can then say the line again.

Testing

Covered downstream, where the relay session runs against a fake WebSocket:

• a caller cutting into text spoken after the turn sets the state at the next turn;
• text played to the end leaves the state unset.

The caller-hangup path was checked by build only; it has not been run on a real call. There is no test project here that covers the Twilio plugin.

🤖 Generated with Claude Code

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Code Review by Qodo

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PR Summary by Qodo

Report ConversationRelay caller hang-ups and interrupted post-turn speech

✨ Enhancement 🕐 20-40 Minutes

AI Description

• Notify session hooks when a caller hangs up without an agent handoff.
• Tell the next turn when the caller interrupted text spoken after the previous turn.
• Clear the interruption state on turns without a post-turn cut-in.

Diagram

graph TD
  R["Twilio Relay"] --> A["Action callback"] --> H["Caller hang-up hook"]
  R --> S["Relay session"] --> C["Turn callbacks"] --> P["Conversation processor"] --> T["Conversation state"]

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High-Level Assessment

The following are alternative approaches to this PR:

1. Record post-turn playback cut-offs in conversation history

• ➕ Keeps the interruption alongside the transcript for later readers.
• ➖ Requires revising text already stored when playback occurs after the turn.
• ➖ Adds history-mutation complexity to a signal the next turn needs immediately.

Recommendation: Use the proposed next-turn state for flow decisions: it avoids retroactively changing stored text, while the action callback provides call-status context for the hang-up hook. Review the timing of the playback flag against WebSocket interrupts, since that determines whether the signal accurately means the caller missed text.

Files changed (6) +58 / -1

Enhancement (6) +58 / -1

TwilioConversationRelayController.csEmit a hook for completed calls without an agent hang-up +5/-0

Emit a hook for completed calls without an agent hang-up

• The relay action callback now emits OnCallerHangUp when the call is completed and the agent-hang-up branch was not taken. Transfer and reconnect handling remain ahead of this branch.

src/Plugins/BotSharp.Plugin.Twilio/Controllers/TwilioConversationRelayController.cs

ITwilioSessionHook.csExpose an optional caller-hang-up hook +9/-0

Expose an optional caller-hang-up hook

• Adds OnCallerHangUp with a default no-op implementation, allowing existing hook implementations to remain compatible.

src/Plugins/BotSharp.Plugin.Twilio/Interfaces/ITwilioSessionHook.cs

AgentTurnCallbacks.csCarry the previous post-turn cut-off into an agent turn +6/-0

Carry the previous post-turn cut-off into an agent turn

• Adds a boolean callback property that conveys whether the caller cut into text spoken after the preceding turn.

src/Plugins/BotSharp.Plugin.Twilio/Models/AgentTurnCallbacks.cs

ConversationRelayStates.csDefine the last-reply cut-off state key +7/-0

Define the last-reply cut-off state key

• Adds twilio_relay_last_reply_cut_off for flows that need to detect missed post-turn speech.

src/Plugins/BotSharp.Plugin.Twilio/Models/ConversationRelayStates.cs

ConversationRelaySession.csTrack interruptions of text spoken after a turn +23/-1

Track interruptions of text spoken after a turn

• Records when unstreamed reply text is about to be spoken and whether a subsequent interrupt occurs. Passes that result to the next turn's callbacks, then resets the tracking flags.

src/Plugins/BotSharp.Plugin.Twilio/Services/ConversationRelaySession.cs

TwilioConversationProcessor.csExpose the cut-off marker to the next conversation turn +8/-0

Expose the cut-off marker to the next conversation turn

• Sets the application conversation state to "true" when the callback reports a post-turn cut-off; otherwise removes the state before the turn proceeds.

src/Plugins/BotSharp.Plugin.Twilio/Services/TwilioConversationProcessor.cs