Systematic trace through Zed (crates/agent_ui thread_view.rs + crates/acp_thread): kind:execute routes a tool call onto the terminal-card layout, whose header (render_collapsible_command) has NO disclosure toggle, whose body content renders only when is_open — a flag only a real terminal entity can ever set — and which suppresses the Raw Input view outright. Every prior attempt (rawInput, pending content, completed content) targeted slots that layout structurally never renders; the one slot it always shows is the TITLE, which said "Run code". codex-acp confirms the idiom: execute cards are titled with the command itself. presentCall now titles the card with the program (rawInput kept as the canonical input slot); presentResult omits the title — an update replaces only provided fields, so the program header persists — and carries the captured output as content. Goldens re-recorded; the unit test pins title-carries-program on both frames.
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.