[Bug]: aws-strands adapters drop non-text tool result content from TOOL_CALL_RESULT

[dsturnbull]

Pre-flight Checklist

• I have searched existing issues and this hasn't been reported yet.
• I am using the latest version AG-UI.

Describe the Bug

Both aws-strands adapters translate a Strands toolResult into an AG-UI TOOL_CALL_RESULT event by walking the result's content blocks. Only some block types are read, so any result whose payload is non-text is silently lost: no error, no warning, and the client sees no data.

The two SDKs drop it differently:

• Python (ag_ui_strands): the content loop only handles a text block. A result made of a json, image, document, or video block (with no text block) leaves result_data = None, and the guard if not result_tool_id or result_data is None: continue skips the block entirely, so no TOOL_CALL_RESULT is emitted at all.
• TypeScript (@ag-ui/aws-strands): the loop reads TextBlock and .json, so json results forward correctly, but ImageBlock / DocumentBlock / VideoBlock fall through, leaving resultData = null. The event still fires but collapses to content: "", so the media payload is dropped.

Net effect: a tool that returns an image, document, or video (and, on Python, json) produces either a missing or empty tool result on the wire.

Steps to Reproduce

1. Register a Strands tool that returns a non-text result, e.g. an image: { "toolResult": { "toolUseId": "...", "content": [ { "image": { "format": "png", "source": { "bytes": <bytes> } } } ] } } (Python) or a tool yielding an ImageBlock (TypeScript).

2. Run the agent through the aws-strands adapter and capture the emitted AG-UI events.

3. Observe the TOOL_CALL_RESULT: on Python no event is emitted for that tool call; on TypeScript the event is emitted with content: "". The image/document/video payload never reaches the client.

Expected Behavior

A tool result carrying a json/image/document/video block (but no text block) should still produce a non-empty TOOL_CALL_RESULT whose content carries the block's serialized payload (e.g. { "image": { "format": "png", "source": {...} } }).

A genuinely void tool (empty content array) should continue to emit content: ""; that behaviour is intended and should be preserved.

Both adapters should behave identically here.

Environment

AG-UI package(s) & version(s): @ag-ui/aws-strands@0.2.3 (TypeScript, depends on @strands-agents/sdk ^1.1.0, @ag-ui/core >=0.0.37); ag_ui_strands 0.2.3 (Python, depends on strands-agents >=1.15.0,
ag-ui-protocol >=0.1.18)

Runtime: Node 22 / Python 3.12

Model provider: any (the bug is in the adapter's event translation, not the model)

Screenshots

No response

Logs & Errors

Additional Context

#1978 is the same "no text block" failure mode on the input side (convert_agui_content_to_strands produces a document-only Strands message that Bedrock rejects); this report is the output side counterpart.

#1593 notes that TOOL_CALL_RESULT has no structured field for non-text payloads, so a fix serialises the media block into the existing string content field rather than a new structured field; #1593 remains the proper long-term home for structured tool output.