Concepts

HZL is a durable coordination ledger for stateless agent sessions.

Core mental model

• Agents wake as fresh sessions.
• Durable state lives in HZL, not in memory.
• Workflows encode common multi-step transitions on top of task primitives.

Installation model

HZL is installed once per machine and stores data per user account.

Component	Location	Scope
CLI binary	Global (npm/Homebrew)	Per machine
Database	~/.local/share/hzl/ (default)	Per user account
Projects	Optional namespaces in DB	Shared pools

Simplicity through constraints

One level of nesting

Project (optional)
└── Task
    └── Subtask (max depth 1)

Agent identity is free-form

--agent is a string identity. HZL does not require registration.

Dependency graph is global

Dependencies can connect tasks across projects. Use hzl dep list filters for visibility.

Core primitives

• Projects
• Tasks
• Subtasks
• Dependencies
• Pruning
• Checkpoints
• Claiming & Leases
• Lifecycle Hooks
• Cloud Sync

What HZL does not do

• No orchestration runtime
• No automatic task decomposition
• No hidden prioritization policy beyond command semantics