agent-creator

# Agent Creator Guide the user to a correct, immediately-loadable Pythinker agent definition. The hard part is not the file format — it is a sharp `when_to_use`, a scoped tool set, a persona that earns its keep, and a structured output contract. The builtin agents under `src/pythinker_code/agents/default/` (`plan.yaml`, `explore.yaml`) are the quality bar; match them. Do NOT invent a new loader or code path. Two existing, additive mechanisms already load custom agents — pick the one that fits and write a file. No changes to `agentspec.py`, the CLI, or the runtime are needed. ## Two ways to define an agent ### A. Markdown agent file (quick, auto-discovered) — preferred default A single `<name>.md` placed in a discovery directory is auto-discovered on the next launch. Frontmatter fields recognized by `parse_markdown_agent`: - `name` — the agent name (falls back to the filename stem). - `description` — what it is (falls back to the first body line). - `when_to_use` — when the orchestrator should delegate to it (falls back to `description`). - `tools` — a YAML list of **friendly tool names**, mapped to import paths automatically — do NOT use the `module:ClassName` form here. The supported names are: `Agent`, `Bash`, `Edit`, `Fetch`, `Glob`, `Grep`, `Read`, `TodoWrite`, `WebFetch`, `WebSearch`, `Write`. - `model` — optional model alias. The markdown **body** is the agent's system prompt (its persona + rules + output contract). ```markdown --- name: migration-reviewer d...