Sessions & context

Human-facing `/compact` control over `ctx.compaction`. The plugin registers one global command through `ctx.commands`, so every composed command adapter discovers and executes it without a model turn. The queued manual compaction Agent Note owns the admission, lock, and durability decisions.

The **basic compaction backend**: a `BasicCompactionEngine` implementing the `@deepseek-ai/dsh-compaction` Service Definition with reusable `ctx.tokenMeter` pressure, token-budget retention, and summarization as a direct one-shot `ctx.llm.stream()` call that replays the conversation prefix to reuse the provider's KV cache (interceptable at `llm/stream`).

The replay-safe model-free pruning service (`ctx.toolResultPruner`). It rewrites over-budget `tool/result` surface nodes to a bounded head, a fixed omission marker, and a bounded tail while retaining the full original event in the append-only session log.

Per-session workspace instruction loading for `AGENTS.md`-compatible files. The plugin injects the initial user-global and project instruction chain into durable history, then discovers nested files and reports later changes or removals after successful filesystem tool calls.

`ctx.sessionReferenceResolver` prepares bounded, read-only snapshots of other sessions as sourced model-facing context. It consumes `ctx.sessionQuery` and the backend-independent compact checkpoint marker; SQLite FTS is not required. Hosts that support cross-session mentions may opt into the service.

Opt-in durable context with the current zoned time, the browser zone attached to the open request, and elapsed time sampled during model-request preparation. Default compositions leave it disabled; the Schedule Web overlay mounts it so the model can interpret otherwise-unqualified dates and times in the user's browser zone. Decision record: the durable time-context Agent Note.

Opt-in durable context naming the tmux session, window, and pane this agent process runs in, plus the window's pane-tree layout. It is sampled once per turn during model-request preparation and is not part of the shipped Web/headless composition. Decision record: the tmux-context Agent Note.

Web Session-log download control over the host-streamed ZIP endpoint owned by `dsh-host-apiproxy`. The Host half registers `/export`; the browser half owns a 111×32 `Session log` action in the Session Header, one download controller, and one modal shared by that button and the slash command. ZIP generation, raw JSONL/zstd reads, descendants, attachments, backpressure, and HTTP error semantics remain owned by the ApiProxy download implementation.

Concrete `ctx.sessionQuery` provider. `SqliteSessionQueryEngine` inherits exact reads, traces, and provider-independent filters from the Service Definition package and implements its two full-text methods with SQLite FTS5. Search uses the live-preferred logical session corpus and groups cross-session results by their strongest event.

Semantic durability policy for persisted agents. It checkpoints the event-sourced session before a model adapter receives a request, before a top-level tool body may produce an external side effect, and at each `agent/pre-step` boundary so the preceding response and ordered tool results are durable before the next request.

The JSONL durable session-persistence backend — a concrete `SessionPersistence` (the `dsh-session-persistence` seam). Each session has one append-only logical JSONL log, stored as `.jsonl.zstd` by default or raw `.jsonl` when compression is disabled.

A SQLite durable session-persistence backend — a second `SessionPersistence` provider (session persistence) satisfying the same contract as `dsh-session-persistence-jsonl` (append-only, contiguous-seq, lazy materialization, interrupted-turn close on load), expressed over `node:sqlite` rows instead of file bytes.

Session-projection Service Definition and drive registry. It owns `ctx.sessionProjections`, the registry that drives every registered projection unit over committed session events and serves finished whole values to carriers, currently the api-proxy history tail page and `session/projection` push frame. A domain registers pure mathematics; the framework owns the drive. The session-projection RFC records the design rationale.

The persisted projection cache (`ctx.sessionProjectionCache`): durable checkpoints of every registered projection unit's state, one record per session on the domain data form (`session_projcache` domain — the shipped json backend lands it beside `workspace.json` under the configured storage root). Design authority: the session-projection RFC (persisted projection cache section).

Function plugin registering the `sessionStats` projection unit: whole-log conversation figures — turn/step counts and the LLM, tool, first-token, and decode wall times — folded from step boundaries, stream chunks, tool pairs, and assembled assistant messages, and served through the session-projection seam (registry snapshot, change feed, and every projection carrier: history tail page, `session/projection` push frames, session list rows). Clients render full-session figures that paging and compaction cannot change; the reference consumer is the web chat stats strip, whose window fold mirrors these field names as its no-unit fallback.

The OpenTelemetry backend for the telemetry seam — the only entry a deployment loads. Its `mode` decides whether the seam follows session events live, replays the canonical log only at recorded feedback, or keeps telemetry local. Uploading modes compose the OTel JS SDK as-is (`LoggerProvider` → `BatchLogRecordProcessor` → OTLP/HTTP log exporter) and map each handed-over record onto `logger.emit()`, under two instrumentation scopes: ledger records on `@deepseek-ai/dsh-session-sessionTelemetry-otel`, operational records on `@deepseek-ai/dsh-session-sessionTelemetry-otel/ops`. Resource identity contains `service.name`/`service.version` from `dsh-llm`'s `APP_IDENTITY` plus this package's anonymous `user.id` (`$DSH_HOME/.anonymous-user-id`, a random UUID created on first use and reset by deleting the file), carried once per export batch rather than per record.

Log-backed session titles with an immediate deterministic fallback and one optional asynchronous provider. Every accepted revision is a log-only `session/title` event; `foldSessionTitle()` and `ctx.sessionTitle.get()` select the latest event and return its event seq and timestamp.

Optional `ctx.sessionTitle` provider that summarizes every eligible human message through `ctx.llm`. It registers the `all-prompts` cadence and starts a new revision after each new human prompt, using seeded history as well as child-session prompts. A newer revision aborts and supersedes older work; even a provider that ignores cancellation cannot commit stale output.

Optional `ctx.sessionTitle` provider that summarizes the first eligible human message through `ctx.llm`. It registers the `first-prompt` cadence, runs automatically only when a fresh non-fork session first creates its fallback, and attributes the result to that message's exact seq. An automatic failure retains the fallback and is retried only through `ctx.sessionTitle.refresh()`.