Yichen Jiang
765052a7d1
ds-review-bot critical (follow-up): on the first step of a resumed or seeded/forked instance, auto-compaction ran before runStep composed this instance's prefix, so the gate read the PREVIOUS instance's logged prefix from the header fold — a contributor that grew across resume/fork (skills added, AGENTS.md grown: exactly the environment-dependent case) could under-gate and ship an over-window first request. The loop now composes agent/session-prefix before the instance's first agent/pre-step (still once per instance; runStep just reads the cache), and agent/pre-step carries the composed prefix to its listeners. CompactService.compactIfNeeded gains the sessionPrefix parameter; BasicCompactService.estimatePressure gates on the handed value — the header-fold read is gone, so the estimate is exact at every step including a resumed/forked instance's first. Composition moving before the boundary snapshot also means a composing listener's session append now joins the CURRENT request (documented on the seam). New coverage: composition precedes pre-step and the seam receives the composed prefix; cancel and disposal landing inside the composition window drop the step cleanly; the compact gate test hands the prefix directly.
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 |
|---|---|---|
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) |
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.