Tianyi Cui
2be60b9a22
The session event vocabulary carried two standalone trace-only events that
were not load-bearing as separate records. Fold their facts into nearby
load-bearing events and delete the standalone variants.
- Token usage now rides on `assistant/message` as an optional `usage` field —
the assembled model output and its accounting travel together. The loop folds
`assembler.usage` onto the append instead of emitting a separate `usage`
event.
- The max-tokens path is the no-data-loss host: a step cut off with usage but
EMPTY content (e.g. only a dropped tool call) previously emitted a standalone
`usage`; it now records an empty-content `assistant/message { content: [],
usage }`. `deriveMessages()` skips empty-content assistant messages, so the
usage host never injects a spurious content-less assistant turn into the
provider transcript. A step with neither content nor usage appends nothing.
- An operational error's step number now rides on `turn/end.reason` for
`kind: 'error'` (`{ kind: 'error', step, message, code? }`) — the durable
turn outcome ACP and resume already consume. `failTurn` sets the reason
directly (no separate session `error` event). `agent/error` + logging are
unchanged for live diagnostics.
- No format-version bump: pre-release, no persisted data, so per the format
policy there is nothing to migrate or reject (the RFC's "refresh the format
version" criterion over-reached). `version` stays 1.
- ACP fixtures + goldens re-recorded (keyless replay): dropped standalone
usage/error lines, usage folded onto assistant/message, error step on
turn/end.reason.
RFC moved proposed -> implemented with an implementation note recording the two
scope refinements.
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/execute waterfall |
ctx.tools |
agent/ |
Agent interface, registry, agent/* event vocabulary |
ctx.agents |
agent-loop/ |
The concrete loop plugin: ReactLoopAgent + the loop driver |
ctx.agentLoop |
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.