Add Lens

One trace per agent turn, visible in the Lens UI under the agent's agent_id. Lens runs inside redis-iris; it has no service to provision and no CLI. Two lines at start-up, one turn per message, then close the gaps the agent has. Lens sits next to any other Iris product, or none.

Full reference: Lens (docs/core/lens.md in redis-iris).

1. Discover

Read the project:

• The turn: where one user message becomes one answer (app.invoke, Runner.run, runner.run_async, agent.run, kickoff, or the handler around a hand-written loop).
• The ids: where the agent's own name lives, and where each request's session or thread id and user id live. Always set both agent_id and session_id. Every Lens UI view is filtered by agent_id, so a trace without one never shows. Turns are shown grouped by session, so a turn without a session id does not show either (showing turns without a session is an upcoming feature).
• Start-up: the one place that runs before the first turn (app factory, main, worker boot).
• The model client: the library that finally calls the model, under any framework. Lens instruments four: openai, anthropic, botocore (Bedrock) and langchain_core. Many frameworks call one of these underneath; confirm in step 2. Any other client (for example google-genai or litellm) records no LLM span and no tokens unless step 6 adds an instrumentor for it.
• Existing telemetry: opentelemetry, TracerProvider, opentelemetry-instrument, OTEL_* variables, or another LLM instrumentation. Note who installs the global provider and when.
• The gaps in step 5: .client calls, custom retrieval, thread pools, process hops, short-lived processes.

Then match the shape. It decides who opens the turn: