The long-term design for flow functions, decided from the templates evaluation. A flow function (script node) is a pure compute step — and ALL data I/O stays declarative on the flow graph.

Why pure-function (not a data API on the function)

The AI templates wrote invoke_function expecting the function to update the record directly, but flow functions get FlowFunctionContext (input/variables/automation/logger) — no data API, by design. That boundary is correct for a metadata-first, AI-authored platform:

• Visible: data effects stay on the flow graph (update_record), not hidden in code.
• Governed: writes go through the engine's data path (RLS, tenancy, transactions, hooks) — a raw function data-API would bypass that (the managedBy is not enforced: generic CRUD bypasses better-auth on sys_team (data-integrity / security) #1591 class).
• Build-checkable: declarative writes are validated at objectstack build; opaque function I/O is exactly the "passes build / fails at runtime" class this season fought.
• Two-tier already correct: L2 hooks are the data-lifecycle layer (they get ctx.api); flow functions are orchestration compute.

So the fix makes the pure-function pattern ergonomic, not the imperative one work.

What's added

• config.outputVariable — exposes the function's return value as a flow variable, so a later declarative node persists it.
• config.inputs are interpolated against live flow variables (they were passed raw) — so a function can consume a prior node's output.

{ id: 'ai', type: 'script', config: { function: 'helpdesk.aiTriageStub', inputs: { ticketId: '{record.id}' }, outputVariable: 'ai' } },
{ id: 'apply', type: 'update_record', config: { objectName: 'helpdesk_ticket', filter: { id: '{record.id}' },
    fields: { ai_category: '{ai.ai_category}', ai_sentiment: '{ai.ai_sentiment}' } } },

Also

• Skill: automation pitfall [WIP] Create a new release version #9 now teaches this pattern (function returns → outputVariable → update_record; hooks for data side effects).
• Tests: +1 end-to-end (compute → outputVariable → downstream node interpolates {ai.field}); @objectstack/service-automation 202 pass; check:skill-docs passes.

This is the framework foundation for the templates' #1870 remediation (restructure the 4 AI flows to function-returns + update_record).

🤖 Generated with Claude Code