round 1: implement bracket-first manual compaction

packages/compact/compact-basic/README.md

@@ -17,11 +17,11 @@ This backend owns the compaction policy:
 - **Convergence** — retry head-checkpoint compaction up to `compactionRetries`; reject a summary that does not shrink its source, and throw if retries cannot return below threshold.
 - **Summarization** — a direct `llm/stream` call uses the configured provider/model pair and cap, falling back to the latest logged request target and then the agent target, without running the loop-only `agent/request` seam. The call replays the conversation's own system prompt, tools, and shadowed-region messages verbatim and appends the compaction instruction as the final user message, so it reuses the provider's warm prefix cache instead of invalidating it. It sets `GenerateOptions.purpose` to `compaction`, which adapters may forward as request attribution (the DeepSeek adapter sends `x-deepseek-harness-compact: 1`) without touching the model-visible body. Only returned text enters the checkpoint, excluding reasoning and tool calls that would leak private reasoning or create an orphaned call.
 - **Framing** — the replacement user message marks established checkpoint context with `<compacted-summary>` tags. The raw summary remains on the provenance event, and later automatic cycles merge the prior checkpoint.
-- **Lifecycle** — `compactRegion()` mutates `agent.session` and records its start, summary, replacement, and end. After asynchronous summarization it rejects a changed surface-node snapshot, while unrelated log-only events may append without invalidating the selected span. The serial `agent/step` listener checks pressure before request derivation. A canonical provider overflow is offered through `agent/request-error` after the failed step; the plugin compacts there and returns a retry action only after durable surface progress.
+- **Lifecycle** — all entry points share one bracket-first region transaction. It validates the range and live lock, appends `compact/start` synchronously, prepares and awaits the summary, revalidates, appends provenance plus the replacement, and makes exactly one closing attempt. Automatic and explicit-region calls require a numeric open-turn owner and whole-surface stability. `compactNow()` reserves idle admission, uses `turn: null`, accepts append-only context outside its selected span, flushes every closed attempt, and releases admission in `finally`.
 - **Overflow recovery** — provider-confirmed overflow needs no capacity metadata: it bypasses normal pressure and retention, prunes, then attempts one maximal balanced head reduction while leaving the newest indivisible unit. Retry is authorized whenever `surface.replaceGeneration` advances, including when pruning lands before later summary work throws. No replacement, an exhausted target-specific cap, cancellation, or an unknown/noncanonical error preserves the original provider failure.
-- **Failure handling** — an unmatched `compact/start` is an inert crash marker because no summary replacement landed. A region failure records an error end; the surface remains unchanged unless pruning already landed. Operational pressure failures warn and continue, while overflow-recovery failure preserves the original provider error only when no earlier replacement advanced the surface. Cancellation remains authoritative after any progress.
+- **Failure handling** — a live unmatched `compact/start` is the durable lock. An unmatched marker before a newer `session/end-seed` is stale evidence from a prior lifecycle and does not block; one after that boundary reports `busy`. Summary and changed-span failures close with an error and leave the conversation surface untouched, though the attempt remains in the log. A failed close deliberately leaves a blocking orphan. Operational pressure failures warn and continue, while overflow-recovery failure preserves the original provider error only when no earlier replacement advanced the surface. Cancellation remains authoritative after cleanup and durability.
 
-The protected `summarize()` method is the sole subclass hook. A template- or remote-summarizer subclass can override it while pressure, retention, provenance, shrink validation, and shadowed-token accounting stay on `ctx.tokenMeter`. The hook returns the summary blocks together with the call envelope it used (`{ summary, provider, model, maxTokens? }`), which is logged on `compact/summary`.
+The protected `summarize()` method is the sole subclass hook. A template- or remote-summarizer subclass can override it while pressure, retention, provenance, shrink validation, and shadowed-token accounting stay on `ctx.tokenMeter`. The hook returns the safe summary plus the complete provider output, call envelope, and usage when available (`{ summary, rawOutput?, provider, model, maxTokens?, usage? }`); the transaction preserves those fields on `compact/summary`.
 
 ## Config (`BasicCompactConfig`)
 
@@ -60,7 +60,7 @@ export function apply(ctx: Context): void {
 }
 ```
 
-Loading the plugin registers `ctx.compact`. Add [`dsh-compact-tool-result-prune`](../compact-tool-result-prune/README.md) as a sibling before this plugin to enable the optional model-free pass. With `auto: true` (the default) it compacts automatically under token pressure; a consumer (a future `/compact` tool) can also call `ctx.compact.compactIfNeeded(...)` or `ctx.compact.compactRegion(...)` directly.
+Loading the plugin registers `ctx.compact`. Add [`dsh-compact-tool-result-prune`](../compact-tool-result-prune/README.md) as a sibling before this plugin to enable the optional model-free pass. With `auto: true` (the default) it compacts automatically under token pressure. The sibling [`dsh-command-compact`](../command-compact/README.md) calls `ctx.compact.compactNow(...)`; programmatic callers may also use any seam operation directly.
 
 For example, the same compact plugin can safely serve models with different capacities and one target-specific policy: