Errors & rejection

Two "unhappy path" behaviours, both handled safely.

1. Error isolation

If a node raises mid-run, the failure is isolated to that node: earlier nodes stay completed, the failing node's activity card is marked error, and the run terminates rather than hanging.

review_swarm (swarm): planner ─▶ researcher ─▶ writer

orchestrations:
  review_swarm:
    mode: swarm
    agents: [planner, researcher, writer]
    entry_name: planner

entry: review_swarm

Full runnable project: examples/20_error_and_rejection.

Proven by

tests/e2e/test_cross_cutting.py::test_swarm_node_error_is_isolated_and_run_terminates — the earlier node stays completed, the failing node is marked error, and the run terminates (never stalls).

2. Rejection

Rejection uses the same gate mechanism as human-in-the-loop. When the client resumes an interrupt with {"status": "cancelled"} (or simply does not address it), the gated tool receives a cancellation sentinel ("The user declined to answer.") and the agent proceeds without fabricating an approval. kaboo never silently approves an unaddressed interrupt — the safe default is to cancel.

// resume payload declining the gate
[{ "interruptId": "<id>", "status": "cancelled" }]

Proven by

tests/e2e/test_complex.py::test_rejected_interrupt_finishes_cleanly — a declined gate resumes to a clean RUN_FINISHED with no error and no hang.