Investigate document discovery and citations from agent document search actions

[paullizer]

Summary

Investigate whether agents that find documents through the document search action produce citations in the same shape as standard document-backed chat responses, and whether those citations cause the referenced documents to appear correctly in the UI.

Context

The UI currently surfaces documents based on citation data. It is unclear whether agent-driven document discovery—particularly when an agent invokes the document search action—returns compatible citation metadata and triggers the same document display behavior.

Investigation

• Compare citation payloads from standard document search/chat flows with citations returned after an agent uses the document search action.
• Confirm whether the frontend recognizes and displays agent-discovered documents.
• Identify differences in citation type, fields, source metadata, or event/stream handling.
• Determine whether normalization is needed so all document citations follow one contract.

Acceptance criteria

• Document the citation payload and rendering path for both standard and agent document-search flows.
• Add or update automated coverage for agent-discovered document citations.
• If behavior differs, implement or propose a consistent citation contract that makes agent-discovered documents appear in the UI.
• Verify personal, group, and public workspace behavior where applicable.

[paullizer]

Shipped in v0.250.219 via #1274.

Release note entries:

• v0.250.219: Agent Document Search Now Produces Real Document Citations
• v0.250.219: Collapsed Long Source Lists

Full notes: https://microsoft.github.io/simplechat/explanation/release_notes/

Closing as completed. This issue stayed open after the fix merged because pull requests target Development while the repository default branch is main, so GitHub never applied the Fixes # keyword automatically.