Llm empty plan controller fallback

LLM Empty-Plan Controller Fallback

When to use

Your planning LLM occasionally returns actions: [] (e.g. for healthy or sparse alerts), which would route the agent into a no-op loop. You want the controller to seed at least one verification action so the agent makes progress and either gathers evidence or proves there's nothing to gather.

How it works

• After parsing the LLM plan, if planned_actions is empty AND there are available_action_names (so we can do something), iterate a curated fallback list (most-broadly-useful queries first).
• Pick the first fallback that's available; record it with a clear rationale ("Controller fallback: LLM returned empty plan...").
• If none of the curated fallbacks are available, just take available_action_names[0].

Example

if not planned_actions and available_action_names:
    fallback_candidates = [
        "query_grafana_metrics", "query_grafana_logs",
        "query_datadog_all", "query_datadog_logs",
        "query_honeycomb_traces", "query_coralogix_logs",
        "get_cloudwatch_logs", "get_host_metrics",
        "list_eks_pods", "get_eks_events",
    ]
    for candidate in fallback_candidates:
        if candidate in available_action_names:
            planned_actions = [candidate]
            plan_rationale = "Controller fallback: LLM returned empty plan. Forcing verification action."
            break
    if not planned_actions:
        planned_actions = [available_action_names[0]]
        plan_rationale = "Controller fallback: LLM returned empty plan. Forcing available verification action."

Gotchas

• Pair this with a hard loop cap — if the fallback action returns no useful evidence and the LLM keeps returning empty, you still need an upper bound to terminate.
• The fallback list ordering matters: prefer high-signal/low-cost queries first.
• Always set plan_rationale to a string the user will see in traces; "controller fallback" is honest and easy to grep for in production.