Citations

Citations attach source metadata (document, page, character range, URL) to spans of generated text. Useful for RAG over uploaded files, web-search grounding, and audit trails.

Compatibility

Provider	API	pi-go	Notes
Anthropic	✅ Citations API (citations: {enabled: true} on documents)	⚠️	document-level Citations API not wired; web_search results surface as a numbered title/URL list on ServerToolOutput (anthropic.go, see server-tools.md)
OpenAI Chat	❌	—
OpenAI Responses	✅ inline citations from web/file search	⚠️	web-search action description on ServerToolOutput.Content; full provider JSON retained on Output.Raw (openairesponses.go). No dedicated citation content type yet
OpenRouter (Responses dialect)	✅ response.output_text.annotation.added events with url_citation payloads	❌	events are streamed but ignored — citations are not currently attached to ai.Text spans or to the preceding server-tool call
Google Gemini	✅ groundingMetadata from grounded searches	⚠️	parsed into a synthesized web_search ToolCall; chunks rendered on Output.Content, full metadata on Output.Raw (google.go)
Claude CLI	⚠️ surfaced in CLI output	❌	not parsed

Provider Documentation

• Anthropic — Citations
• Google Gemini — Grounding metadata

pi-go Gaps

• No Citation content type or sub-block on ai.Text. Search-grounded citations currently live as text + raw JSON inside ServerToolOutput, not as structured spans tied to assistant text.
• No way to opt-in citations on document inputs (Anthropic’s citations: {enabled} flag).
• No anchoring of citation chunks to the assistant text spans they support — Gemini’s groundingSupports indices are present in Output.Raw but not promoted to a typed structure.
• Citations interact with Server-Side Tools and File Search — the ServerToolOutput.Raw escape hatch is shared across all of them.