# 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) — requires `checksum`/`checksumSha256`, validates SHA-256, stages bundles to `ArtifactsPath/bundles/{checksum}/{filename}` deterministically, and emits `metadata.json`; 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)
```json
\"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. Gap Remediation (TP1–TP10, 2025-12)
- **Canonical plan hash (TP1):** Plan hash is `sha256:<64-hex>` over `plan.canonicalPlanPath` (normalized JSON, stable key ordering, UTF-8). Hash and canonical plan file are shipped in offline bundles and verified by `scripts/packs/verify_offline_bundle.py`.
- **Inputs lock (TP2):** Task Runner emits `inputs.lock` capturing resolved inputs + redacted secret placeholders; stored in evidence bundles and listed under `hashes[]` in offline manifests.
- **Approval ledger (TP3):** Approval decisions are DSSE-signed, embedding `runId`, `gateId`, `planHash`, and `tenantId`. Approval endpoints reject mismatched plan hashes or missing DSSE envelopes.
- **Secret redaction (TP4):** Evidence/transcripts apply the redaction policy referenced in `security.secretsRedactionPolicy`; secrets are hashed or blanked, never logged in clear text.
- **Deterministic ordering/RNG/time (TP5):** Execution order derives from the canonical graph, RNG seed is derived from `planHash`, and all timestamps are UTC ISO-8601 with monotonic log sequences.
- **Sandbox + egress quotas (TP6):** Runs declare `sandbox.mode` (`sealed`/`restricted`), explicit `egressAllowlist`, CPU/memory limits, and optional wall-clock quota. Missing entries cause fail-closed refusal during plan or execution.
- **Registry signing + SBOM + revocation (TP7):** Packs accepted by Task Runner must include DSSE envelopes for bundle + attestation, a pack SBOM, and a revocation list path; imports fail when digests or revocation proofs are absent.
- **Offline bundle schema + verifier (TP8):** Offline bundles must satisfy `docs/task-packs/packs-offline-bundle.schema.json` and pass `scripts/packs/verify_offline_bundle.py --require-dsse`. Evidence locker records the verifier version used.
- **Run/approval SLOs (TP9):** Plan validation enforces declared SLOs (`runP95Seconds`, `approvalP95Seconds`, `maxQueueDepth`) and wires alert rules into telemetry (burn-rate alerts on approval latency + queue depth).
- **Fail-closed gates (TP10):** Approval/policy/timeline gates default to fail-closed on missing evidence, expired DSSE, or absent quotas; remediation hints surface in `pack_run_logs` and API error payloads.

## 13. 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`.