stem 0.4.0

Experimental Dart-native background job platform with Redis Streams, retries, scheduling, observability, and security tooling.

Changelog

0.4.0

• Added portable ScheduleRunner.runOnce, with Beat retaining the periodic compatibility lifecycle over the same dispatch implementation.
• Allowed publish-only producers to use task-status and group-result stores without implementing worker-heartbeat storage.
• Shared VM and portable execution middleware and retry classification while retaining VM-supervised execution and transport lifecycle handling.
• Fixed signature verification for native delivery-attempt overrides.
• Added JS runtime tests for narrow persistence, one-shot scheduling, mixed batches, and sequential/concurrent duplicate-delivery semantics.
• Added the first portable runtime surface: publisher-only producer APIs, conditional VM task invocation, narrow persistence capabilities, typed task-processing outcomes, and a JavaScript compile guard for portable.dart.
• Raised the minimum Dart SDK to 3.12.0 for the coordinated Ormed 0.3 release train.
• Raised the ecommerce example's minimum Dart SDK to 3.12.0.
• Upgraded Dartastic OpenTelemetry to 0.10.0 and its API to 0.10.0. Stem now benefits from zone-safe context propagation, sampler-correct spans, global propagator configuration, and the SDK's no-processor fast path.
• This release intentionally contains breaking dependency and SDK changes from the 0.2 line.
• Promoted the typed stable/advanced API boundary and removed implicit worker startup from producer, inspection, Canvas, and workflow operations.
• Added capability-aware queue transports, public cooperative cancellation, explicit task execution modes, typed rate limits, heterogeneous Canvas chains, explicit chord policies, and OpenTelemetry Canvas fan-out span links.
• Scheduler dispatch now revalidates distributed lock ownership immediately before publication and records lease-loss failures instead of publishing after ownership has expired.
• Added compatibility-safe fencing-token support to lock handles. Memory, Redis, and Postgres acquisitions expose monotonically increasing tokens; Beat propagates the token on scheduled envelopes for downstream enforcement.
• This release intentionally contains breaking API changes from the 0.2 line.
• The observability entrypoint now exposes Stem-owned logging types and a structured logging facade; the contextual logger types remain internal.
• Lease renewal derives its cadence from the remaining lease, so short visibility leases are renewed before expiry instead of being forced onto the default one-second minimum interval.
• Failed automatic renewals retry on a shorter cadence, and late in-flight renewals cannot recreate timers after a delivery has been cancelled.
• Active-delivery accounting uses worker-local delivery handles, so concurrent redeliveries of one envelope no longer overwrite shutdown or in-flight state.
• Lease timers are keyed by delivery identity rather than receipt text, which keeps same-receipt redeliveries independent for adapters that reuse row IDs.
• Automatic heartbeat timers now use the same delivery identity, preventing a concurrent redelivery from cancelling the original task's heartbeat.
• Lease renewal now remains active through terminal result persistence, group/chord bookkeeping, retry or dead-letter publication, linked-task dispatch, and acknowledgement; slow terminal handling cannot expire the delivery before the worker releases it.
• Lease renewal now starts when a delivery enters the worker, covering slow consume middleware, signature validation, backend lookups, and rate-limit decisions before handler execution.
• Concurrent redeliveries of an envelope already active in the same worker are acknowledged without a second handler invocation; process-wide failures still rely on normal at-least-once recovery.
• Documentation now distinguishes heartbeat/liveness signals from broker lease extension; use automatic renewal or context.extendLease(...) for leases.
• Added the optional AtomicTerminalResultBackend capability. Built-in result backends arbitrate terminal writes so a late cross-worker completion cannot replace the first terminal result; custom backends remain source compatible and retain their previous non-atomic fallback behavior.
• Worker terminal side effects such as group/chord bookkeeping, linked-task dispatch, terminal signals, and unique-lock release now belong only to the worker that wins terminal-result arbitration.
• Added a deterministic lease-loss recovery regression: renewal failure lets a delivery expire, a replacement worker can complete the redelivery, and the original late completion cannot overwrite that terminal result.
• Payload-decoding failures are now terminally failed and dead-lettered as invalid-payload instead of escaping before acknowledgement and redelivering indefinitely. Retry-storm coverage verifies that normal retry budgets remain bounded under concurrent failure.
• Hard-shutdown coverage now verifies that a full broker prefetch window is requeued and completed by a replacement worker, not only a single active isolate delivery.
• Added a warmed-up core throughput benchmark with a checked regression baseline and scheduled CI execution.

0.2.3

• Added additive QueueBroker, LeaseBroker, InspectableBroker, and DeadLetterBroker capability interfaces for new adapter integrations.
• Made managed worker startup explicit for every bootstrap path. Enqueue, status, result-wait, Canvas, and workflow operations never start a worker; applications must call start() (or startWorker()) deliberately.
• Added stable.dart and advanced.dart entrypoints to make the intended API boundary explicit while retaining the historical stem.dart compatibility barrel.
• Made QueueBroker independently implementable; lease, inspection, purge, and dead-letter operations are now optional capability interfaces with compatibility defaults on Broker.
• Extracted isolate execution and pool lifecycle into an internal execution supervisor, and hardened shutdown against late delivery errors after the worker event stream closes.
• Centralized worker event emission so late timers, retries, heartbeats, progress callbacks, and revocation notifications are safely ignored after shutdown.
• Extracted broker subscription ownership and stream error boundaries into an internal worker consumer loop, including safe queue-subscription replacement during pause and resume operations.

0.2.2

• Replaced string rate-limit fields with typed RateLimit values while retaining legacy parsing at JSON/configuration boundaries.
• Added cooperative task cancellation through TaskExecutionContext.cancellation.
• Made memory adapters available through the explicit package:stem/memory.dart library.
• Prevented status and result-wait operations from implicitly starting a worker.
• Moved release validation to dependency-ordered workspace automation and added aggregate package quality gates.
• Added a source-compatible BrokerCapabilities snapshot so adapters can declare optional delivery, inspection, broadcast, lease, and dead-letter behavior without expanding the base broker contract.
• Added queue-broker extension methods for optional dead-letter inspection, replay, and purge operations, allowing integrations to depend on QueueBroker without reverting to the legacy broad Broker type.

0.2.1

• Guarded worker and example process signal registration so Windows only installs supported shutdown watchers, avoiding unsupported SIGTERM / SIGQUIT subscriptions during graceful shutdown setup.

0.2.0

• Added StemClient.fromStack(...) and StemStack.createClient(...) so adapter-resolved broker/backend stacks have the same direct bootstrap path as the higher-level app helpers.
• Narrowed the public task and workflow invocation APIs around direct enqueue(...) / enqueueAndWait(...) and start(...) / startAndWait(...) calls, with explicit transport objects left as the advanced low-level path.
• Removed duplicate transport helpers and wrapper builder entrypoints such as .call(...), prepareStart(...), prepareEnqueue(...), builder dispatch methods, and copyWith(...) on transport objects.
• Added shared execution-context interfaces for workflows and tasks so manual handlers and checkpoints can use one typed context surface instead of several partially overlapping ones.
• Added expression-style suspension and event APIs for workflows, plus direct typed event emit/wait helpers on workflow event refs.
• Added module-first bootstrap improvements including module merge/combine, inferred worker subscriptions, queue/subscription inspection helpers, and shared app/client workflow bootstrap helpers.
• Expanded manual serialization support with json(...), versionedJson(...), versionedMap(...), registry-backed versioned factories, and codec-backed low-level publish/start/emit helpers for tasks, workflows, and queue events.
• Added broad typed decode helpers across runtime, inspection, signal, queue, status, and context surfaces so DTO reads no longer require raw map casts in the common path.
• Refreshed examples and docs to use the narrowed happy-path APIs and to treat transport objects as explicit advanced APIs rather than peer entrypoints.

0.1.0

• Added workflow run leasing APIs (claimRun, renewRunLease, releaseRun, listRunnableRuns) and runtime ownership tracking to safely spread workflows across workers.
• Added TaskRetryPolicy and TaskEnqueueOptions for per-enqueue overrides (timing, retries, callbacks), plus TaskContext/TaskInvocationContext enqueue, spawn, and retry helpers including isolate entrypoint support and a fluent TaskEnqueueBuilder.
• Added inline FunctionTaskHandler execution (runInIsolate toggle) to simplify choosing between inline vs. isolate task execution.
• Added workflow/task annotations and a registry builder to streamline declarative workflow setup with existing Flow/WorkflowScript APIs.
• Added StemClient as a single entrypoint for configuring workers and workflow apps with shared broker/backend registries.
• Added TaskContext demos and refreshed docs/snippets for enqueue options and SQLite guidance.
• Added typed workflow, task, and canvas result APIs with customizable encoders (TaskResultEncoder and payload encoders).
• Added new example suites (progress heartbeat, worker control lab, and the feature-complete set) plus refreshed docs/Taskfiles for running them.
• Added signals registry/configuration for worker, task, scheduler, and workflow lifecycle events.
• Improved worker runtime (isolate pool, config, heartbeats/autoscaling) plus scheduler behavior (timezone alias handling, in-memory schedule store).
• Exposed lock ownership in interfaces and migrated IDs to UUID v7.
• Removed sqlite migrations from core and updated dependencies (collection, contextual, crypto, cryptography, timezone, uuid).
• Expanded internal docs and example suites, plus broader unit/property and workflow store contract coverage.

0.1.0-alpha.4

• Introduced Durable Workflows end-to-end: auto-versioned steps, iteration- aware contexts, and durable event watchers so long-running flows replay safely and resume with persisted payloads.
• Added a WorkflowClock abstraction (with FakeWorkflowClock) so runtimes and stores can record deterministic timestamps during testing.
• Refined sleep/await behaviour: persisted wake timestamps now prevent re-suspending once a delay has elapsed, and saveStep refreshes run heartbeats so active workers retain ownership.
• Updated all workflow stores to consume injected clock metadata, ensuring suspension payloads include resumeAt/deadline values without relying on DateTime.now().
• Wired TaskOptions.unique into the runtime via the new UniqueTaskCoordinator, allowing clusters to deduplicate submissions using shared LockStores and surface duplicate metadata when a clash occurs.
• Workers now coordinate chord callbacks through ResultBackend.claimChord, persisting callback ids and dispatch timestamps so fan-in callbacks run exactly once even after crashes or retry storms.

0.1.0-alpha.3

• Split Redis/Postgres adapters and CLI into dedicated packages (stem_redis, stem_postgres, stem_cli) so the core package only exposes platform-agnostic runtime APIs.
• Updated examples, docs, and integration guides to reference the new packages.

0.1.0-alpha.2

• Replace the legacy opentelemetry dependency with dartastic_opentelemetry and update tracing/metrics integrations.
• Add _init_test_env helper to start dockerised dependencies and export integration env vars.
• Refresh project docs to mention the new telemetry stack and test environment workflow.
• Bump direct dependencies (dartastic_opentelemetry 0.9.2, postgres 3.5.9, timezone 0.10.1) and align transitive packages.

0.1.0-alpha

• Initial version.