Problem

• Workflow authors cannot repeat a multi-node DAG fragment inside one loop iteration; loop: only repeats a single prompt today.
• This affects Archon workflow authors using DAG YAML, especially build/test/fix, plan/implement/validate, and adversarial multi-role loops.
• It comes up whenever one iteration needs multiple nodes with explicit dependencies; current workarounds are a giant loop prompt [!] or extracting a child workflow.

Proposed Solution

Allow inline composite loops: a loop body that can contain a small sub-graph (nodes) executed once per iteration until the loop exit condition passes.

Related: #972 currently prefers workflow composition over nesting. This request is specifically for inline composite loops when extraction is too heavy or hurts readability.

User Flow

Before (current)

Author wants: plan -> implement -> validate -> repeat until done

workflow nodes
  -> single loop node
     -> [!] must collapse all three phases into one prompt
        OR
     -> [!] extract a separate child workflow just to get iteration over multiple steps

After (proposed)

workflow nodes
  -> composite loop
     -> [+] iteration body runs plan -> implement -> validate sub-graph
     -> [+] loop exits when until/until_bash condition passes
     -> [+] parent workflow sees one loop node output

Alternatives Considered

Scope

• Package(s) likely affected: workflows, possibly server and web for validation/editor support
• Breaking change? (No)
• Database changes needed? (No)
• New external dependencies? (No)

Security Considerations

• New permissions/capabilities? (No)
• New external network calls? (No)
• Secrets/tokens handling? (No)
• If any Yes, describe:

Definition of Done

• Workflow schema can express a composite loop body with nested nodes
• Executor can run the loop body per iteration with scoped outputs and stop conditions
• Tests covering the feature
• Documentation updated (if user-facing)