L1-L2-L3 Three-Tier Memory Agent Foundation: reatcat/l123-harness

The core philosophy of the DeepSeek Harness (DSH) plugin `reatcat/l123-harness` is "everything is a plugin." It provides capabilities such as an L1-L3 three-tier memory system, gate approvals, and event logging. The plugin bridges lifecycle events via Hooks to enable L1 resident memory, automatic L2 index injection, and L3 detail management, while supporting TDD workflows and dual-host compatibility. The installation command is `dsh plugin --profile web add github:reatcat/l123-harness`. Note that local development should use a tarball package to avoid dependency issues, and the `PreCompact` and `SessionEnd` events are not currently implemented.