git.stella-ops.org/docs/modules/taskrunner/architecture.md

TaskRunner Architecture (v1)

Canonical contract for TaskRunner delivery scoped by SPRINT_0157_0001_0002 (TaskRunner Blockers) and SPRINT_0157_0001_0001 (TaskRunner I). Anchored in product advisory "29-Nov-2025 - Task Pack Orchestration and Automation" and the Task Pack runbook/spec (docs/task-packs/*.md).

1. Purpose and Scope

• Execute Task Packs deterministically with approvals, sealed-mode enforcement, and evidence capture.
• Provide API/CLI surface for pack submission, status, logs, approvals, artifacts, and cancellation.
• Produce provenance: DSSE attestation + evidence bundle for every completed run.
• Operate offline/air-gapped with plan-hash binding and sealed-mode network allowlists.

2. Components

• WebService (StellaOps.TaskRunner.WebService) - HTTP API, plan hash validation, SSE log streaming, approval endpoints.
• Worker (StellaOps.TaskRunner.Worker) - run orchestration, retries/backoff, artifact capture, attestation generation.
• Core (StellaOps.TaskRunner.Core) - execution graph builder, simulation engine, step state machine, policy/approval gate abstractions.
• Infrastructure (StellaOps.TaskRunner.Infrastructure) - storage adapters (Mongo, file), artifact/object store clients, evidence bundle writer.

3. Execution Phases

1. Plan - parse manifest, validate schema, resolve inputs/secrets, build execution graph, compute canonical planHash (SHA-256 over normalised graph).
2. Simulation (optional) - dry-run graph; emit determinstic preview with approvals/policy gates highlighted.
3. Execution - verify runtime graph matches planHash; execute steps honoring maxParallel, continueOnError, map/parallel semantics; stream logs/events.
4. Evidence - capture artifacts + transcripts, emit DSSE attestation binding planHash, inputs/outputs, steps, and timestamps; expose artifact listings via API for post-run retrieval.

4. API Surface (v1)

• POST /api/runs (packs.run) - submit pack run; requires manifest/version, inputs, tenant context; returns runId + planHash.
• GET /api/runs/{runId} (packs.read) - run status (graph, attempts, pending gates).
• GET /api/runs/{runId}/logs (packs.read) - SSE stream of ordered log events.
• GET /api/runs/{runId}/artifacts (packs.read) - list captured artifacts with digests/paths.
• POST /api/runs/{runId}/approve (packs.approve) - record approval gate decision (requires Authority token claims pack_run_id, pack_gate_id, pack_plan_hash).
• POST /api/runs/{runId}/cancel (packs.run) - cancel active run.
• TODO (Phase II): GET /.well-known/openapi (TASKRUN-OAS-61-002) after OAS publication.

5. Data Model (Mongo, mirrors migration doc)

• pack_runs: _id, planHash, plan, failurePolicy, requestedAt, createdAt, updatedAt, steps[], tenantId.
• pack_run_logs: _id, runId, sequence (monotonic), timestamp (UTC), level, eventType, message, stepId?, metadata.
• pack_artifacts: _id, runId, name, type, sourcePath?, storedPath?, status, notes?, capturedAt.
• Indexes as defined in docs/modules/taskrunner/migrations/pack-run-collections.md.

6. Step Types and Semantics

• run – module invocation; declares inputs/outputs.
• parallel – executes nested steps[]; honors maxParallel.
• map – expands items into child steps (stepId[index]::templateId).
• gate.approval – human approval checkpoint; enforces TTL/required count; pauses run until satisfied or expired.
• gate.policy – Policy Engine evaluation; failAction decides halt vs. continue.
• Built-in helper: bundle.ingest (run step) — validates optional checksum/checksumSha256, stages bundles to ArtifactsPath/bundles/<file> deterministically; fails on missing file or checksum mismatch.

7. Determinism, Air-Gap, and Security

• Plan hash binding: runtime graph must equal planned graph; mismatch aborts run.
• All timestamps UTC ISO-8601; ordered logs via (runId, sequence) unique index.
• Secrets never logged; evidence bundles store only redacted metadata.
• Sealed mode: reject non-allowlisted network calls; approvals can be processed offline via request/response bundles.
• RBAC scopes: packs.read, packs.write, packs.run, packs.approve.
• Approval enforcement: service rejects approval decisions when provided planHash does not match stored run state (protects against stale/forged tokens).

8. Evidence & Attestation

• DSSE attestation payload (payloadType: application/vnd.stellaops.pack-run+json) includes runId, packName/version, planHash, input/output digests, step statuses, completedAt.
• Evidence bundle contents: signed manifest, inputs (redacted), outputs, transcripts, DSSE attestation; optional Rekor anchoring when online.

9. Observability (Phase I delivered)

• Metrics: step latency, retries, queue depth, resource usage (TASKRUN-OBS-50/51-001 DONE).
• Pending: timeline events (TASKRUN-OBS-52-001), evidence snapshots (TASKRUN-OBS-53-001), attestations (TASKRUN-OBS-54-001), incident mode (TASKRUN-OBS-55-001).

10. Integration Points

• Authority - approval tokens, scope validation, sealed-vault secrets.
• Policy Engine - gate.policy decisions, policy context in evidence.
• Export Center - evidence bundles and manifests for offline/air-gapped export.
• Orchestrator/CLI - submission + resume flows; SSE log consumption.

11. Configuration (Mongo example)

\"TaskRunner\": {
  \"Storage\": {
    \"Mode\": \"mongo\",
    \"Mongo\": {
      \"ConnectionString\": \"mongodb://127.0.0.1:27017/taskrunner\",
      \"Database\": \"taskrunner\",
      \"RunsCollection\": \"pack_runs\",
      \"LogsCollection\": \"pack_run_logs\",
      \"ArtifactsCollection\": \"pack_artifacts\",
      \"ApprovalsCollection\": \"pack_run_approvals\"
    }
  }
}

12. References

• Product advisory: docs/product-advisories/29-Nov-2025 - Task Pack Orchestration and Automation.md.
• Task Pack spec + authoring + runbook: docs/task-packs/spec.md, docs/task-packs/authoring-guide.md, docs/task-packs/runbook.md.
• Migration detail: docs/modules/taskrunner/migrations/pack-run-collections.md.