## Summary
Adds a "Build a chat agent" guide to the AI agents section, surfaces the
ClickHouse chat agent example in the guides index and the AI agents
overview,
and refreshes the five existing workflow guides so their code is
current.
## Details
The pattern guides (prompt chaining, routing, parallelization,
orchestrator,
evaluator-optimizer) still used retired models and dated APIs. Updated
them to
current Anthropic Claude models (claude-haiku-4-5 for lightweight
classifier
roles, claude-sonnet-4-5 for the main work) and modernized the code:
- route-question uses generateObject for the routing decision instead of
generateText plus manual JSON parsing.
- verify-news-article uses ModelMessage in place of the renamed
CoreMessage.
- Fixed translate-and-refine discarding its recursive refinement result,
so
refined translations never returned to the caller.
- Fixed an invalid JSON test payload in generate-translate-copy.
The pattern concepts are unchanged; only the example code was stale.
DKP
e367899510