path-config-strings.md

Milestone: env_file / repo_root / dirs paths must be strings

Status: Shipped
PR: #109
Depends on: milestones/visual-map-field-strings.md (PR #108)

Problem

manim.manim_path is already a string at config load. These path keys were not:

1. env_file / repo_root — a YAML list loaded successfully, then Path / list TypeError’d when CLI applied the env file or the wizard resolved repo_root.
2. dirs.narration / audio / animations / recordings / hints — a list TypeError’d during Config.__post_init__ Path joins instead of raising ConfigError.

Goal

Fail closed at Config.from_yaml with ConfigError. Missing keys still use defaults (narration/, git-discovered repo root, no env_file).

Done when

• Present env_file / repo_root must be non-empty YAML strings.
• Present dirs.narration / audio / animations / recordings / hints must be non-empty YAML strings.
• Tests for list values of those keys.
• ruff check src/ tests/
• pytest tests/
• docgen benchmark (no clock change)

Out of scope

• wizard.default_guidance type gating is separate.
• Per-segment generation system_prompt / class_name are separate.
• pages output directory keys are separate.