Build Centralized Devlog CLI and Agent Skill

Summary

Built a Go CLI that accepts structured JSON from coding agents, validates and renders entries as Markdown, stores them safely by project, initializes local Git storage, and includes user and agent documentation.

Decisions

• Keep devlog add plus its JSON schema as the stable contract between agents and storage
• Use standard-library UUIDv7 generation for stable time-sortable entry identities without adding dependencies
• Use exclusive file creation and numbered suffixes to prevent collision overwrites
• Keep the agent skill focused on invoking the CLI instead of reproducing storage behavior

Learnings

• A narrow CLI contract lets agent workflows remain stable while storage implementation details evolve
• Agent-facing skill instructions benefit from a concise bundled reference separate from the human-facing project manual