Lab 2 — Streaming & Tool-Calling Agent

Summary — what this page covers Attendees add a streaming endpoint and a multi-tool agent to BookTracker — committed. The agent calls real C# functions against the database before producing its final answer. Keep steps exact.

Duration: 35 min · Deliverable: streaming endpoint + multi-tool agent — committed

Part A — Streaming endpoint (≈15 min)

Implement SSE streaming so tokens appear one at a time. Use client.Messages.CreateStreaming, surface the text deltas as IAsyncEnumerable<string> from a StreamingService, and write each as a data: frame, flushing per chunk (see Section 2). Verify with:

curl -N http://localhost:5000/api/chat/stream?q=hello
# Tokens should appear one at a time, not all at once at the end

Part B — Tool-calling agent (≈20 min)

Define 2+ tools wired to real BookTracker services (e.g. find_book, update_reading_progress), each with a clear, trigger-style description. Run the agent loop until StopReason is EndTurn — the BetaToolRunner handles the loop for you, or write a manual loop if you want to log each call. Cap iterations and return is_error tool results on failure. Verify multiple tool calls fire:

# Ask something that needs two lookups, e.g.:
#   "Find Dune and mark it as completed"
# Should see 2+ tool calls in the logs before the final response

Checkpoint

• Streaming endpoint emits tokens incrementally
• Agent makes 2+ tool calls before its final response
• Tools read/write real BookTracker data
• Committed to your fork

Bonus — The Streaming Agent

No time pressure. Combine both halves into one endpoint: run the tool-calling agent loop, then stream the final answer token-by-token after the last tool call completes — the agent acts on real data and feels responsive.