Why: User overrides of a subagent profile need a place on the shared contract, and empty fields must stay omitted so older modules keep their meaning.
Evidence: go test ./... passed, including the new prompt_module_subagent golden.
Impact: Existing modules serialize the same. Frontend and UI contracts still need a copy of the type.
Refs: feature/agent-harness-p3b
Co-authored-by: Cursor <cursoragent@cursor.com>
Why: prompts are moving from code into a data library; core needs the
PromptModule/Trigger/Block contract and profiles need an ordered
promptModules reference (empty = default base+env set).
Evidence: unit-covered via backend prompts package tests over this
contract; composite make test green.
Impact: additive contract fields only; no behavior change in core.
Refs: feature/prompt-library task card.
weichenandCursor