deepseek-harness/packages/core

core/ — product API spine

The packages every harness build is assembled from: the session log, the system-prompt assembly, the tool registry, the agent vocabulary, and the one concrete loop that drives them. 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/	Tool registry + tools/pre-execute/tools/post-execute pipeline	ctx.tools
agent/	Agent interface, registry, agent/* event vocabulary	ctx.agents
agent-loop/	The concrete loop plugin: ReactLoopAgent + the loop driver	ctx.agentLoop
agent-core/	Bundle plugin: the providerless/executor-less/UI-less spine as code	(loads the spine)

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.

agent-core is the composition counterpart: one bundle plugin that loads the whole providerless spine (timer + llm + sessions + system-prompt + tools + agents + invariants + tool-bash + agent-loop) and forwards agent-loop's agents list as its own config. App packages (ui/stdio-agent, ui/acp-agent) consume it and add only a front door; a leaf adds the swappable backends plus any optional product tools it wants to expose. It lives in core/ because it composes exclusively core/ + interface packages and ships no provider, executor, or UI of its own.