🤖 feat: add prompt.append for agent body inheritance #1389
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- Add prompt.append field to agent schema (default: false = replace) - When true, child agent's body is appended to base agent's body - Add resolveAgentBody() to handle inheritance chain resolution - Deprecate Mode sections in AGENTS.md → project-local agents - Add .mux/agents/exec.md and plan.md with prompt.append: true - Update docs with inheritance behavior explanation - Add tests for resolveAgentBody
- When inheriting from a base agent, child body is now appended by default - Set prompt.append: false to explicitly replace the base body - Updated docs to reflect new default behavior - Removed now-redundant prompt.append: true from project-local agents
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…#1402) ## Problem After the agent definitions merge (#1389), Mux broke when project-local agents tried to extend built-in agents of the same name. For example: ```md # .mux/agents/exec.md --- name: Exec base: exec # Tries to extend built-in exec --- Project-specific additions. ``` This caused either: - An infinite loop (readAgentDefinition kept finding the same project file) - False cycle detection (since both project/exec and built-in/exec have ID "exec") ## Solution 1. **Add `skipScopesAbove` option to `readAgentDefinition`**: When resolving a base agent with the same ID as the current agent, skip the current scope and look at lower-priority scopes (global, then built-in). 2. **Track visited packages by `(id:scope)` tuple**: This allows the same agent ID to appear at multiple scopes in the inheritance chain without triggering false cycle detection. A real cycle would still be detected (same id AND same scope). 3. **Update both resolution paths**: - `resolveAgentBody()` for system prompt inheritance - `resolveAgentInheritanceChain()` for tool policy inheritance ## Testing - Added test: "same-name override: project agent with base: self extends built-in/global, not itself" - Added test: "readAgentDefinition with skipScopesAbove skips higher-priority scopes" - All existing agent tests pass ## Documentation Added new section "Extending Built-in Agents" in docs/agents.mdx explaining the pattern. --- _Generated with `mux` • Model: `anthropic:claude-opus-4-5` • Thinking: `high`_
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Summary
Adds control over how agent body prompts compose during inheritance.
Default (append): Child body is appended to base body—intuitive for project-local agents extending built-ins.
Explicit replace: Set
prompt.append: falseto discard base body entirely.Changes
prompt.appendfrontmatter field (default: true)resolveAgentBody()for recursive body resolution with cycle detectionExample
To replace instead:
Generated with
mux• Model:anthropic:claude-opus-4-5• Thinking:high