welt-io 0.2.1

Agent-side adapters for Welt's wire contract

welt-io

Agent-side adapters for Welt's wire contract.

Install

uv add welt-io

Usage

from collections.abc import AsyncIterator

from bedrock_agentcore.runtime import BedrockAgentCoreApp
from strands import Agent
from welt_io import decode_file_blocks, renderable_events

app = BedrockAgentCoreApp()


@app.entrypoint
async def invoke(payload: dict) -> AsyncIterator[dict]:
    messages = payload["messages"]
    decode_file_blocks(messages)  # base64 file bytes -> raw bytes, in place
    agent = Agent()
    # Reduce the stream to the JSON-serializable events Welt renders
    async for event in renderable_events(agent.stream_async(messages)):
        yield event


if __name__ == "__main__":
    app.run()

Adapters

The wire between Welt and your agent is JSON, and plain Strands values do not fit it in either direction.

Inbound

decode_file_blocks(messages) restores the base64-encoded file bytes in Welt's Converse-shaped messages (built from Slack uploads) back to the raw bytes Strands expects, in place. Without uploads it is a no-op.

Outbound

renderable_events(events) reduces raw stream_async events — not JSON-serializable as-is — to the events Welt renders: text chunks (data), tool-use indicators (current_tool_use / tool_result, slimmed so text tool output stays off the wire), and generated files (file, a filename plus base64 bytes for each image/document/video block a tool or the model produces, which Welt uploads to the Slack thread).

file_event(name, data) builds the same file event from a filename and raw bytes, for attaching arbitrary files of your own:

yield file_event("report.csv", csv_bytes)

License

MIT