SessionQueryService is the combined abstract ctx.sessionQuery contract. It implements exact session-history retrieval, relationship tracing, and provider-independent filtering over live ctx.sessions plus optional dynamically mounted ctx.sessionPersistence; concrete backends implement its two full-text methods. Matching ids produce one record: live events win, while live and persisted report both source availabilities. Conflicting immutable headers fail with SESSION_QUERY_SOURCE_CONFLICT.

Reads

listSessions() reads current persistence metadata, merges live records with live precedence, and returns cloned records in deterministic newest-first order.
filterSessions(filters) applies provider-independent session metadata and availability predicates to that same cloned logical corpus.
filterEvents(sessionId, filters) extracts first-party semantic documents and applies provider-independent metadata and literal-text predicates in ascending seq order.
readTitle(sessionId) loads one live-preferred or persisted log and folds its latest session/title event into a SessionTitleSnapshot; it returns undefined when the known session has no title.
listEvents(sessionId) loads the live-preferred raw log and classifies each event as current, shadowed, or log-only with the shared dsh-session surface fold.
readSurface(sessionId) returns one cloned header, raw-log capture boundary, and the complete folded current surface in model-history order. A live session wins over persistence; compaction is observed before or after its replacement append, never as a synthetic mixture.
readEvent(request) returns a cloned header, the full target event, and a bounded raw-seq window. before and after default to zero and may not exceed readWindowMax.
traceSession(sessionId) reads the corpus once and returns immediate-to-outward ancestors plus deterministic recursive descendant trees. complete: false identifies the first missing parent; a target-connected cycle fails with SESSION_QUERY_INVALID_LINEAGE.
traceEvent(request) loads the logical log once and returns direct positional replacements and direct logged provenance. replacementChain follows positional replacers to the final replacement; provenance links remain non-transitive.

Persistence is optional and may mount or unmount dynamically. Cross-corpus listing and lineage tracing fail with SESSION_QUERY_PERSISTENCE_FAILED while mounted persistence is unreadable. A title, event read, or trace targeting a known live session does not consult persistence, so durable backend health cannot make current in-memory state unreadable. Persisted title and event operations list before loading and reject a metadata mismatch rather than combining inconsistent observations. listSessions() remains lightweight and does not load logs or index titles.

Filtering and extraction

SessionResultFilter covers id, nullable cwd, created-at range, nullable parent, and source availability. SessionEventResultFilter covers seq/time ranges, event type, surface, and semantic text. Filter arrays are ANDed; values within one list clause are ORed. Empty list values match nothing, ranges are inclusive, and malformed ranges or closed-union values fail with SESSION_QUERY_INVALID_FILTER.

The text clause is deliberately independent of FTS providers: caller text is escaped into a Unicode, case-insensitive regular expression, and each whitespace run matches one or more whitespace characters. It is a literal semantic-text scan, not a full-text query. extractSessionEventText() and buildSessionEventSearchDocuments() define the shared first-party document projection; structural boundaries, stream chunks, request headers, and unknown declaration-merged variants produce no document.

Full-text methods

SessionQueryService.searchSessions(request, exec?) groups the logical corpus by strongest matching event; searchEvents(request, exec?) searches one logical session. These are the service's only abstract methods. Both return pages whose continuation is an owned branded SessionSearchCursor, accept optional cancellation, and expose snippets without provider-specific numeric scores. Search requests accept only metadata event filters, because literal-text filtering is the scan path described above.

The package has no provider coordinator, fallback implementation, or standalone concrete plugin. A concrete service backend inherits the implemented reads, filters, and traces while owning full-text observation, reconciliation, ranking, cursor generations, and query execution; the first implementation is @deepseek-ai/dsh-session-query-sqlite.

SessionQueryError.code is a closed union covering request validation, missing targets, malformed surfaces, source conflicts, persistence/index failures, cancellation, and invalid or stale cursors; the exact literals are defined in src/config.ts.

listEvents(), readSurface(), and traceEvent() run the same one-pass dsh-session surface fold. A loaded log is valid only when event seqs are zero-based and contiguous, surface markers obey event-type eligibility, provenance arrays are nonempty and duplicate-free, references name earlier events, and each positional replacement names and cites every surface node it removes; every violation fails with SESSION_QUERY_INVALID_SURFACE.

Configuration

Key	Default	Contract
`readWindowMax`	`50`	Maximum `before` or `after` raw-event count.

Model Experience

None, as this trusted query service returns cloned session records only to its callers and registers no model-facing prompt, schema, tool, or message.

KV Cache effect

None; this package neither assembles nor sends a provider request.

Known Limitations and Deferred Work

No caller authorization — this is trusted context-wide infrastructure; a future model tool or UI must constrain which sessions its caller may inspect.
No registries or model-facing tool — extractor and search-provider registries, recursive event-provenance traversal, and a model-facing tool are absent. The tracing decision owns relationship semantics; SQLite ownership and tokenizer decisions live in the implemented search note.