fix(delegation): add per-turn spawn cap to prevent runaway delegate_task loops

[Slobaka]

Problem

delegate_task has max_concurrent_children (bounds batch size per call) and max_spawn_depth (bounds nesting), but neither limits how many times the parent agent calls delegate_task in a single user turn. A model stuck in a loop can spawn thousands of sequential subagents, exhausting tokens and API budget.

Fix

Add delegation.max_spawns_per_turn config key (default: 10). Track _turn_spawn_count on the parent agent. Each delegate_task call checks current_turn_spawn_count + n_tasks > max_spawns_per_turn and returns a tool_error directing the model to synthesize a response or split work across turns.

Files changed

• tools/delegate_tool.py — _get_max_spawns_per_turn(), check in delegate_task(), _DEFAULT_MAX_SPAWNS_PER_TURN = 10
• agent/conversation_loop.py — reset _turn_spawn_count at turn start
• tests/tools/test_delegate_per_turn_spawn_limit.py — full test coverage

Config

delegation:
  max_spawns_per_turn: 10  # default; raise deliberately

Like max_concurrent_children there is no upper ceiling — but a high value multiplies API cost linearly.

Verification

Rebased against main (9be292f, 2026-07-01). Confirmed upstream does not contain max_spawns_per_turn or _turn_spawn_count.

[teknium1]

Thanks for identifying a real remaining delegation budget gap. Current main caps calls only within each assistant response (agent/conversation_loop.py:4734, run_agent.py:3863-3891) and validates each tasks batch independently (tools/delegate_tool.py:2465-2474), so cumulative same-turn fan-out is still possible.

Problems

• tests/tools/test_delegate_per_turn_spawn_limit.py:50-82 does not call delegate_task; it only asserts local arithmetic. It therefore does not verify rejection, state mutation, or turn reset.
• The proposed config surface is absent from hermes_cli/config.py:2242-2301 and the delegation docs at website/docs/user-guide/configuration.md:1989-2011.
• Existing direct-call tests construct a MagicMock parent without _turn_spawn_count (tests/tools/test_delegate.py:41-61) and invoke delegate_task (:231-243); the new counter path needs that fixture/state handled explicitly.

Suggested changes

• Add the default, docs, and dynamic schema disclosure for the cap.
• Add executable multi-call and reset tests through patched delegate_task, and seed the existing parent fixture with an integer counter.

The PR predates the async-concurrency refactor in 6e369a376, so salvaging the helper into current tools/delegate_tool.py needs conflict-aware transplantation rather than a clean cherry-pick.

Automated hermes-sweeper review.

[teknium1]

This only reimplements the comparison locally; delegate_task() is never invoked. Please test sequential patched calls through the tool and assert the second call returns its tool error without constructing children, then verify a new conversation turn resets the counter.