Compatibility matrix

What the reference engine (@agent-workflow/engine) supports today versus what the schema accepts or defers to hosts.

Tier legend:

• Core — required for profile conformance; supported in reference engine
• Optional — allowed in documents; engine may or may not implement
• Refused — schema may accept shape but engine rejects at validate or runtime

Feature matrix

Feature	Tier	Engine 0.1.2	Notes
document, state_schema, nodes, edges	Core	Supported	No top-level extensions
start, end, step, llm_call, tool_call, switch, interrupt	Core	Supported	Graph walker + linear runner
parallel, wait (duration/until), set_state	Core	Supported	wait.until uses engine clock
agent_delegate, subworkflow	Core	Supported	Mock A2A; child refs via registerWorkflowRef
switch via config.cases / default	Core	Supported	Prefer over static edges from switch
Reducers: overwrite, append, merge	Core	Supported	custom rejected
jq on switch, set_state, mappings	Core	Supported	Subset documented
Checkpointing + definitionHash	Core	Supported	Resume/submit verify definition
interrupt in parallel branch	Refused	Validate + runtime refuse	INTERRUPT_IN_PARALLEL_BRANCH
wait kind: signal	Optional (host)	Runtime error without host	Needs workflow_signal host
Per-node retry / timeout	Optional	Not applied	Schema accepts; walker ignores
tool_call delegation bridge	Optional (legacy)	Supported	Prefer agent_delegate
Definition signing	Optional	Not implemented	R4 security story
REST / SDK parity	Optional	Partial	MCP stdio is reference surface

Author guidance

1. Validates ≠ runs — retry, timeout, and wait.signal may pass schema but fail or no-op at runtime.
2. Register subworkflow refs — packaged npm installs do not auto-discover child URNs from disk.
3. Delegate protocols — production A2A/MCP/SDK adapters are not bundled; mock A2A only in reference engine.

Full developer reference: profile model.