[FEATURE] route specific sub-agents to a different API endpoint/key

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Problem: Claude Code sub-agents (spawned via the Agent tool) always inherit the parent session's

API credentials and base URL. There is no way to specify a different API key, ANTHROPIC_BASE_URL, or custom headers on a per-agent basis.

Use case: In enterprise/corporate environments, users may have multiple LLM gateway accounts with different model access (e.g., one gateway ID with Sonnet access, another with Opus access). The current design makes it impossible to run a Sonnet parent session while delegating specific sub-tasks to an Opus agent on a different gateway — even though the user has legitimate access to both.

Proposed Solution

Requested behavior: Allow the Agent tool invocation (or a session/profile configuration) to optionally override ANTHROPIC_API_KEY, ANTHROPIC_BASE_URL, and/or ANTHROPIC_CUSTOM_HEADERS for a specific spawned sub-agent.

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

API and model interactions

Use Case Example

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Additional Context

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