Thread - Aion Docs

This page describes the Thread type from aion-authoring-langgraph. The Thread object is the main fluent surface for replying, posting, and emitting streaming intents without forcing authors to build raw A2A messages by hand.

Properties

Property	Purpose
`context_id`	Current messaging thread or context identifier
`parent_context_id`	Parent thread or context identifier when one exists
`network`	Originating network or distribution identifier
`default_reply_target`	Canonical reply target derived from the inbound event
`message`	Normalized inbound `Message`, or `None` when no inbound message exists

Methods

Method	Purpose
`from_context(context)`	Class method. Create a `Thread` from an `AionRuntimeContext`
`reply(content, *, metadata=None)`	Add a durable reply to the current thread
`post(content, *, target=None, metadata=None)`	Create an explicit outbound post action
`history(limit=20, offset=None)`	Not implemented yet; currently returns an empty list
`typing(content, *, metadata=None)`	Emit a stream-only typing or progress intent

reply(...) and post(...) accept the same content categories:

plain text (str)
AIMessage or AIMessageChunk
async iterator of str or AIMessageChunk for streaming replies
a Card object — provider-neutral card document
an a2a.types.Artifact built with url_artifact, file_artifact, or data_artifact

`reply(...)`

reply(...) is intended for the most common case: answer in the same place the inbound message arrived.

from langchain_core.messages import AIMessage, AIMessageChunk
from langgraph.runtime import Runtime

from aion.core.a2a import data_artifact, file_artifact, url_artifact
from aion.core.agent.invocation.card import Card, Text
from aion.core.runtime import AionRuntimeContext
from aion.langgraph.authoring import Thread


async def node(state: State, runtime: Runtime[AionRuntimeContext]) -> dict:
    thread = Thread.from_context(runtime.context)

    # Plain text
    await thread.reply("Thanks. I'm looking into that now.")

    # LangChain message types
    await thread.reply(AIMessage(content="Done."))
    await thread.reply(AIMessageChunk(content="Streaming chunk..."))

    # Async iterator — streamed live, accumulated as a durable reply
    async def generate():
        for word in ["Processing", " your", " request..."]:
            yield word

    await thread.reply(generate())

    # Card — see /sdk/python/messaging/card for all creation modes
    await thread.reply(Card("Report ready").add(Text("All checks passed.")))

    # Artifacts — see /sdk/python/messaging/artifacts for the full reference
    await thread.reply(url_artifact("https://example.com/report.pdf", mime_type="application/pdf", name="report"))
    await thread.reply(file_artifact(pdf_bytes, mime_type="application/pdf", name="report"))
    await thread.reply(data_artifact({"score": 0.95}, name="result"))

    return {}

`post(...)`

post(...) is intended for explicit outbound actions that should remain distinct from the default reply target.

async def node(state: State, runtime: Runtime[AionRuntimeContext]) -> dict:
    thread = Thread.from_context(runtime.context)
    await thread.post("Posting a follow-up note to a different channel.")
    return {}

Unlike reply(...), post(...) should remain explicit in the response buffer so cross-target delivery is never inferred from transcript order alone.

`history(...)`

history(...) is reserved for asking the control plane for more context than was included on the inbound turn.

async def node(state: State, runtime: Runtime[AionRuntimeContext]) -> dict:
    thread = Thread.from_context(runtime.context)
    recent = await thread.history(limit=5)
    return {}

history() is not implemented yet and currently returns an empty list.

`typing(...)`

typing(content, *, metadata=None) is intended for stream-only live intents. content is a required string — the transient text shown to the user while the agent is working.

async def node(state: State, runtime: Runtime[AionRuntimeContext]) -> dict:
    thread = Thread.from_context(runtime.context)
    await thread.typing("Thinking...")
    return {}

These intents should not replace the durable response precedence. They are best-effort live hints for streaming views.

Python SDK

LangGraph

Google ADK

Thread

Properties

Methods

`reply(...)`

`post(...)`

`history(...)`

`typing(...)`

​Properties

​Methods

​reply(...)

​post(...)

​history(...)

​typing(...)

​Related Pages

Properties

Methods

`reply(...)`

`post(...)`

`history(...)`

`typing(...)`

Related Pages