{"version":"2.0.59","anchor":"main-thread-agent-definition-support","canonical_anchor":"main-thread-agent-definition-support","heading":"Main Thread Agent Definition Support","tier":null,"area":null,"scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.0.59\/e\/main-thread-agent-definition-support","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.0.59","markdown":"### Main Thread Agent Definition Support\n\n**What:** New architecture allowing main thread agents to provide custom system prompts.\n\n**Details:**\n\n- New `mainThreadAgentDefinition` parameter added to main UI component at line 480951\n- `HJ9()` helper function at line 480920 handles system prompt resolution\n- Conditionally calls agent's `getSystemPrompt()` method with tool context\n- Enables more flexible agent customization\n- **Evidence**: 7 occurrences in v2.0.59, zero in v2.0.58"}