Sidecar (parasitic tap)
A side-agent rides beside the main agent chain, tapping events without being on the primary path. Typical memory-harvesting pattern.
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A side-care agent rides alongside a primary agent chain, tapping its events without sitting in the critical path. It observes, logs, evaluates or enriches, a side-car, so the main flow stays unblocked while a second agent does cross-cutting work. It is the shape behind observability, guardrail and evaluation layers that must watch everything but block nothing. In anatomy terms it is a passive tap on the transport, with its own core.
A side-car reasoning core subscribes read-only to the primary chain's event stream; it does not sit in the request path; its own effectors handle logging, alerting or enrichment; the perimeter still gates any action it takes.
- ·Observability and tracing over a live agent.
- ·Guardrail and evaluation layers scoring outputs out of band.
- ·Enrichment: annotating events without slowing the main flow.
- ·Adds cross-cutting behaviour without blocking the main path.
- ·Decoupled: it can fail without breaking the primary.
- ·Easy to add or remove.
- ·A central place for observability and guardrails.
- ·Read-only by design: it observes but cannot stop in-path unless promoted to a gate.
- ·Eventual, not synchronous: there is lag between event and reaction.
- ·Another moving part to run and secure.
- ·Can miss events if the tap drops.
Description, use cases and trade-offs: Field Book analysis, synthesised from established agent-architecture literature.
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