fix(delegation): prevent credential pool from overriding explicit delegation.base_url

[kyssta-exe]

Description

Fixes #61195

When delegation.base_url is explicitly configured (e.g. https://api.anthropic.com) while the primary model uses a different provider (e.g. openrouter), the subagent's agent.base_url, agent.provider, and agent.api_mode are correctly resolved to the delegation values throughout init_agent(). However, the credential pool leasing in _run_single_child() could later call _swap_credential(), which overwrites self.base_url (and self._client_kwargs['base_url']) with values from the pool entry — potentially restoring the parent agent's OpenRouter endpoint and causing 401 authentication failures.

Fix

Skip credential pool assignment in _build_child_agent() when override_base_url is set from the delegation config (delegation.base_url). This ensures the explicitly configured endpoint is always honored and never overwritten by a stale pool entry.

Rationale

When the user explicitly configures delegation.base_url, they are directing subagents to a specific endpoint. A credential pool that was loaded for the same provider name (e.g. anthropic) may contain entries with a different runtime_base_url than the one configured in delegation.base_url, because the pool was set up for a different use case (e.g. rate-limiting rotation on the parent's provider).

The credential pool is still available for subagents that inherit the parent's provider (where override_base_url is not set), preserving the rate-limit rotation feature for the default case.

Test Plan

• pytest tests/tools/test_delegate.py -v
• pytest tests/tools/test_async_delegation.py -v
• Manual: configure delegation.base_url to a different provider than the primary model, trigger delegate_task, verify the subagent's API calls go to the configured endpoint

[alt-glitch]

This was generated by AI during triage.

Duplicate of #13752 (earliest open PR for this fix). Both skip the child credential-pool binding when override_base_url (from delegation.base_url) is set — the identical guard on the same _resolve_child_credential_pool call in tools/delegate_tool.py, so _swap_credential can't clobber the child's explicit endpoint. Related: #59670 and #39862 fix the same root cause (subagent credential-pool contamination) via a different mechanism (kill-pool-on-any-explicit-override / provider-match guard). Marking this a duplicate of the canonical #13752; maintainers should choose between the guard approaches.

[teknium1]

Thanks for tracing the credential-pool lease path. This is an automated hermes-sweeper review; current main already prevents the reported OpenRouter-to-Anthropic endpoint retargeting, so this PR is redundant.

• tools/delegate_tool.py:3061-3063 resolves direct https://api.anthropic.com delegation as provider="anthropic" with anthropic_messages transport.
• tools/delegate_tool.py:2980-2988 reuses a parent credential pool only for the same provider; otherwise it loads the child's provider-scoped pool. An OpenRouter parent pool cannot therefore be attached to this Anthropic child.
• tools/delegate_tool.py:1743-1752 leases only the pool already attached to the child.
• This provider-isolated child-pool behavior and its regression coverage were introduced by f2c11ff30cd5601a4017cae64cbbeac0a481f5c9; current coverage remains at tests/tools/test_delegate.py:1717-1726.
• The linked report [Bug]: delegation.base_url correctly resolved through init_agent() but subagent's actual API call still routes to OpenRouter → 401 #61195 was also verified and closed against current main on this basis.

The proposed unconditional skip would also remove valid child-provider credential rotation for every explicit direct endpoint.