feat(compact-basic): baseline compaction backend (squashed from compact-basic)

Collapses the per-round review churn of the prior compact-basic branch into a
single clean baseline on top of compact-interface, so the upcoming retention
refactor lands as fresh, well-scoped commits rather than stacking on a history
of fixes that are being superseded.
This commit is contained in:
Hypatia May
2026-06-25 17:30:42 +08:00
parent 4c1b7191f3
commit aa9afcefc7
23 changed files with 2628 additions and 27 deletions

View File

@@ -1,6 +1,6 @@
# Compaction
The compaction seam — a [capability seam](../rfc/implemented/architecture/2026-06-13-capability-seams.md) split like bash: interface ([dsh-compact](../../packages/compact/compact), `ctx.compact`), implementation (a backend such as `dsh-compact-basic`, deferred), and consumer (a `/compact` tool, deferred). Compaction is **one optional capability**, not part of the agent-loop spine — so its vocabulary lives here, not in [core.md](core.md). A tokenizer- or template-based backend is a sibling package implementing the same interface. Unlike bash, the interface necessarily depends on `dsh-session` and `dsh-llm`: its verbs are defined over a `Session` and its output is the `ContentBlock` vocabulary (see the [compaction capability-seam RFC](../rfc/proposed/feature/2026-06-18-compaction-capability-seam.md)).
The compaction seam — a [capability seam](../rfc/implemented/architecture/2026-06-13-capability-seams.md) split like bash: interface ([dsh-compact](../../packages/compact/compact), `ctx.compact`), implementation (a backend such as [dsh-compact-basic](../../packages/compact/compact-basic)), and consumer (a `/compact` tool, deferred). Compaction is **one optional capability**, not part of the agent-loop spine — so its vocabulary lives here, not in [core.md](core.md). A tokenizer- or template-based backend is a sibling package implementing the same interface. Unlike bash, the interface necessarily depends on `dsh-session` and `dsh-llm`: its verbs are defined over a `Session` and its output is the `ContentBlock` vocabulary (see the [compaction capability-seam RFC](../rfc/proposed/feature/2026-06-18-compaction-capability-seam.md)).
Source: [`packages/compact/compact/src/types.ts`](../../packages/compact/compact/src/types.ts)
@@ -11,7 +11,7 @@ Compaction extends [`SessionEventMap`](session.md) with three event types via de
| Event | Payload | Role |
|---|---|---|
| `compact/start` | `{ turn }` | acquires the log-recorded lock |
| `compact/summary` | `{ summary, shadowedRange, shadowedSeqs, shadowedTokenCount }` | provenance: the summary blocks, the shadowed seq range, and the estimated token count |
| `compact/summary` | `{ summary, shadowedRange, shadowedSeqs, shadowedTokenCount }` | provenance: the summary blocks, the shadowed surface-boundary pair (`start`/`end` seqs — a position span, not a numeric interval), the shadowed seqs in surface order, and the estimated token count |
| `compact/end` | `{ turn, error? }` | releases the lock (`error` set when summarization threw) |
The lock brackets the **whole** operation: `compact/start` is appended first, then summarization, the `compact/summary` provenance record, and the `user/message` replacement all land, and only then `compact/end`. Releasing the lock last turns a crash mid-operation into a detectable orphaned lock (a `compact/start` with no matching `compact/end`) rather than a `compact/end` that falsely claims compaction finished.
@@ -32,9 +32,16 @@ interface CompactionResult {
endSeq: number
/** The summary content blocks produced by the backend. */
summary: ContentBlock[]
/** The seq range that was shadowed [start, end] inclusive. */
/**
* The surface-boundary pair that was shadowed: the seqs of the first
* (`start`) and last (`end`) surface nodes of the replaced range. A
* surface-POSITION span, not a numeric seq interval — after a prior replace
* lands a fresh high-seq summary node at an older range's position, `start`
* can be GREATER than `end`. {@link CompactionResult.shadowedSeqs} is the
* authoritative set of shadowed nodes, in surface order.
*/
shadowedRange: { start: number; end: number }
/** The seq numbers of all shadowed surface nodes. */
/** The seqs of all shadowed surface nodes, in surface order. */
shadowedSeqs: number[]
/** Estimated token count of the shadowed content. */
shadowedTokenCount: number