[rigel-mintaka]

What does this PR do?

Adds optional per-call helper tiers to delegate_task. With delegation.tiers configured, the model must name easy, medium, or hard on every spawn, and each tier routes the child to its own model. A spawn without a known tier is refused and no child starts. Without delegation.tiers, behaviour is unchanged.

This is the fork half of Nemo's model-roles design: Hermes names a helper tier on every delegation, with no default tier.

Related Issue

RIG-8770 (Linear).

Type of Change

• ✨ New feature (non-breaking change that adds functionality)

Changes Made

• tools/delegate_tool.py
  • New tier parameter. The schema requires it only when tiers are configured.
  • _resolve_delegation_tier_routing_config validates the tier.
  • A selected tier is a complete route. It drops the base model, provider, base_url, api_key, api_mode, request_overrides and fallback_providers.
  • A model-only tier keeps the parent runtime provider.
• Enforcement covers model-facing spawns only. Registry dispatch and run_agent.py pass enforce_tier=True.
  • Control actions (list, steer, cancel) need no tier.
  • Internal callers (/review, the lifecycle API) keep the base route unless they pass a tier.
• agent/subagent_lifecycle.py: launch(..., tier=) uses the same resolver. With tiers configured, it rejects a tier combined with a per-launch model or provider.
• Docs: website/docs/user-guide/features/delegation.md, subagent-lifecycle-api.md, and the cli-config.yaml.example tier block.

How to Test

1. Red first: the new tier tests failed before the change ('error' in {'ok': True}; children got fixture/default).
2. Run scripts/run_tests.sh tests/tools/test_delegate*.py tests/agent/test_review_engine.py tests/agent/test_subagent_lifecycle.py -j 2 with the API keys empty: 39 files, 342 passed, 0 failed.
3. Ruff 0.15.10 is clean on the changed files.

Checklist

Code

• Conventional Commits
• One concern
• Tests cover missing or unknown tier, each tier route, batches, control calls, /review exemption, lifecycle, route isolation, and unconfigured tiers

Documentation & Housekeeping

• User and developer docs updated

For New Skills

N/A.

Screenshots / Logs

N/A.

Refs RIG-8770

Co-authored-by: Matt Wilkinson matt@rigel.build

[linear-code]

RIG-8770

[rigel-mintaka]

Review rounds

Round 1 (e26afc9): 1 high, 2 medium, 1 low. All fixed in 5917ede.

• High: /review was refused when tiers were configured and auxiliary.review was unset. Fixed: tiers are enforced on model-facing spawns only (enforce_tier=True).
• Medium: the lifecycle launch() skipped tiers. Fixed: it takes an optional tier and uses the shared resolver.
• Medium: the base base_url overrode the tier provider. Fixed: a selected tier drops the base route keys.
• Low: the nested acp_args assertion was restored.

Round 2 (5917ede): 3 medium, 2 low. All fixed in 8394323.

• Base request_overrides and fallback_providers leaked into a tier. Fixed: both are dropped.
• Model-only tier behaviour was undefined. Fixed: it inherits the parent runtime, now documented and tested.
• Lifecycle mixed request.provider with the tier model. Fixed: a tier plus a model or provider override is rejected.
• Low: an unconfigured tier is ignored, now documented and tested. Test spacing fixed.

Round 3: all-clear on 8394323. 15 tier tests, 21 review-engine tests and 20 lifecycle tests pass.