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Channel delivery contracts. A Channel pushes an ask_user question to a human on a specific medium (Telegram, Slack, SMS, …) and bridges the human’s reply back into the interactions store by forwarding it to the delivery’s public callback_url. Channels are registered on the app handle (tai42_app.channels) by channel plugins and looked up by name when ask_user is called with channel=.... Delivery either returns None (success) or raises ChannelDeliveryError (any failure) — never a bool. A channel also sends fire-and-forget notifications: notify pushes one ChannelNotification to a human with no interaction, no ticket, and no reply path, under the same loud-failure rule (plain return or ChannelDeliveryError).

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Channel

tai42_contract.channels.Channel
Delivers one question to a human on a specific medium. A channel plugin registers an instance under a name (tai42_app.channels.register); ask_user resolves it by name and calls deliver after the interaction is persisted and its callback ticket is minted. A channel never reaches the interactions store directly: the human’s reply travels back through the delivery’s public callback_url.

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Members

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deliver

tai42_contract.channels.Channel.deliver
Push delivery to the medium, or raise ChannelDeliveryError. Send the question to the resolved recipient — delivery.recipient when set (after checking it against the plugin’s operator allowlist), else the plugin’s operator-configured default — and arrange for the reply to reach delivery.callback_url — either a tappable link carrying the URL, or an inbound-route correlation the plugin stores. Any delivery failure — an unreachable or rejecting medium, a recipient outside the operator allowlist, a required credential or recipient not configured, a bad send response — raises ChannelDeliveryError; a plain return is the only success signal. One send attempt only: retrying is the caller’s decision, never an implicit loop here (no medium API offers an idempotency key, so a blind retry risks a double-send). Parameters

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notify

tai42_contract.channels.Channel.notify
Send a fire-and-forget message, or raise ChannelDeliveryError. No interaction, no ticket, no callback, no reply. Any delivery failure — an unreachable or rejecting medium, a recipient outside the operator allowlist, a required credential or recipient not configured, a bad send response — raises ChannelDeliveryError; a plain return means the medium ACCEPTED the message — not that a human saw it. One send attempt only, no retry. A channel that cannot notify raises NotImplementedError. Parameters

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ChannelDelivery

tai42_contract.channels.ChannelDelivery
One question handed to a channel for out-of-band delivery. callback_url is the public /api/interactions/callback/{ticket} answer sink; the channel arranges for the human’s reply to reach it. recipient is the OPTIONAL caller-requested address (chat id, phone number, …): the channel plugin validates it against its operator-set allowlist and refuses to send to an unlisted address; when omitted the plugin sends to its operator-configured default recipient. It is an address only, never a secret or credential. Attributes

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ChannelDeliveryError

tai42_contract.channels.ChannelDeliveryError
Raised by a Channel when delivering a question fails. Every failure mode — an unreachable medium API, a rejected send, a missing credential, a misconfigured recipient — raises this single typed error. deliver NEVER returns a bool and NEVER silently drops a message: an undeliverable question is a loud failure, so the only success signal is a plain return.

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ChannelNotification

tai42_contract.channels.ChannelNotification
One fire-and-forget message handed to a channel. A notification carries no interaction, no ticket, no callback_url and no deadline: the channel sends the message and nothing travels back. recipient is the OPTIONAL caller-requested address (chat id, phone number, …): the channel plugin validates it against its operator-set allowlist and refuses to send to an unlisted address; when omitted the plugin sends to its operator-configured default recipient. It is an address only, never a secret or credential. Attributes