ctx.agent outputSchema fails when the child delegates to a subagent

Minimal reproduction for eve@0.67.2, scaffolded with eve init. The only changes:

• agent/tools/check.ts: a background workflow tool that calls ctx.agent("agent", { message, outputSchema }).
• agent/subagents/researcher/: a declared subagent the root copy can delegate to.
• agent/sandbox.ts: just-bash, only so the repro needs no VM.

Run

1. npm install
2. AI_GATEWAY_API_KEY=... EVE_LOG_LEVEL=debug npm exec -- eve dev --no-ui
3. npm exec -- eve remote invoke -u http://127.0.0.1:2000 "run check direct"
4. npm exec -- eve remote invoke -u http://127.0.0.1:2000 "run check delegate"
5. Read each session's stream for the check task result.

Result

• direct: completes with { facts: [...] }, matching the schema (2/2 runs).
• delegate: fails with SUBAGENT_EXECUTION_FAILED / "The agent could not produce a result matching the requested schema." (4/4 runs). The child's first turn delegates and yields, and that interim turn fails with OUTPUT_SCHEMA_NOT_FULFILLED. The child's next turn then answers with the researcher's facts as free text, after the caller has already failed.