deepseek-harness/packages/core/README.md

core/ — product API spine

The session log, system-prompt assembly, tool registry, agent vocabulary, and concrete loop that form the harness's default control spine. These are product packages — the stable surface plugins and consumers build against.

Package	Role	ctx key
scope/	Scoped-context registration primitive (scope tags, scope-filtered dispatch)	(library — no ctx key)
session/	Event-sourced session log + in-memory store	ctx.sessions
system-prompt/	Prompt-section + tool-schema assembly registry	ctx.systemPrompt
tools/	Scoped tool registry + pre-policy, guards, around-dispatch, post-policy, and final-result observation	ctx.tools
agent/	Agent interface, registry, agent/* event vocabulary	ctx.agents
agent-loop/	Concrete plugin implementing the public Agent contract and owning the loop driver	ctx.agentLoop

scope/ is the one non-service package here: a dependency-free library (createScope/scopeOf/scopeTarget) the registries and the loop build per-agent scoping on — it sits below session/ and system-prompt/ in the module graph precisely so they can consume it without a cycle.

agent-loop is the one concrete implementation of the agent seam and lives here because it is the harness's default product loop; everything else in core/ is interface/vocabulary. Plugins depend on the agent vocabulary, never on agent-loop directly, so the loop stays swappable.

The default composition that wires this spine into a runnable agent lives in examples/agent-spine-demo: one bundle plugin that loads the control spine plus selected default capabilities (timer + llm + sessions + system-prompt + tools + agents + invariants + the local skill family + tool-bash + workspace-context + agent-loop) and forwards agent-loop's agents list as its own config. It sits in examples/ — ready-to-run demo/reference bundles — not in core/: core/ ships the swappable spine pieces, while a demo bundle picks one concrete composition of them and adds a front door.