# StellaOps Architecture Overview (Sprint 19)

> **Ownership:** Architecture Guild • Docs Guild  
> **Audience:** Service owners, platform engineers, solution architects  
> **Related:** [High-Level Architecture](../07_HIGH_LEVEL_ARCHITECTURE.md), [Concelier Architecture](../ARCHITECTURE_CONCELIER.md), [Policy Engine Architecture](policy-engine.md), [Aggregation-Only Contract](../ingestion/aggregation-only-contract.md)

This dossier summarises the end-to-end runtime topology after the Aggregation-Only Contract (AOC) rollout. It highlights where raw facts live, how ingest services enforce guardrails, and how downstream components consume those facts to derive policy decisions and user-facing experiences.

---

## 1 · System landscape

```mermaid
graph TD
    subgraph Edge["Clients & Automation"]
        CLI[stella CLI]
        UI[Console SPA]
        APIClients[CI / API Clients]
    end
    Gateway[API Gateway<br/>(JWT + DPoP scopes)]
    subgraph Scanner["Fact Collection"]
        ScannerWeb[Scanner.WebService]
        ScannerWorkers[Scanner.Workers]
        Agent[Agent Runtime]
    end
    subgraph Ingestion["Aggregation-Only Ingestion (AOC)"]
        Concelier[Concelier.WebService]
        Excititor[Excititor.WebService]
        RawStore[(MongoDB<br/>advisory_raw / vex_raw)]
    end
    subgraph Derivation["Policy & Overlay"]
        Policy[Policy Engine]
        Scheduler[Scheduler Services]
        Notify[Notifier]
    end
    subgraph Experience["UX & Export"]
        UIService[Console Backend]
        Exporters[Export / Offline Kit]
    end
    Observability[Telemetry Stack]

    CLI --> Gateway
    UI --> Gateway
    APIClients --> Gateway
    Gateway --> ScannerWeb
    ScannerWeb --> ScannerWorkers
    ScannerWorkers --> Concelier
    ScannerWorkers --> Excititor
    Concelier --> RawStore
    Excititor --> RawStore
    RawStore --> Policy
    Policy --> Scheduler
    Policy --> Notify
    Policy --> UIService
    Scheduler --> UIService
    UIService --> Exporters
    Exporters --> CLI
    Exporters --> Offline[Offline Kit]
    Observability -.-> ScannerWeb
    Observability -.-> Concelier
    Observability -.-> Excititor
    Observability -.-> Policy
    Observability -.-> Scheduler
    Observability -.-> Notify
```

Key boundaries:

- **AOC border.** Everything inside the Ingestion subgraph writes only immutable raw facts plus link hints. Derived severity, consensus, and risk remain outside the border.
- **Policy-only derivation.** Policy Engine materialises `effective_finding_*` collections and emits overlays; other services consume but never mutate them.
- **Tenant enforcement.** Authority-issued DPoP scopes flow through Gateway to every service; raw stores and overlays include `tenant` strictly.

---

## 2 · Aggregation-Only Contract focus

### 2.1 Responsibilities at the boundary

| Area | Services | Responsibilities under AOC | Forbidden under AOC |
|------|----------|-----------------------------|---------------------|
| **Ingestion (Concelier / Excititor)** | `StellaOps.Concelier.WebService`, `StellaOps.Excititor.WebService` | Fetch upstream advisories/VEX, verify signatures, compute linksets, append immutable documents to `advisory_raw` / `vex_raw`, emit observability signals, expose raw read APIs. | Computing severity, consensus, suppressions, or policy hints; merging upstream sources into a single derived record; mutating existing documents. |
| **Policy & Overlay** | `StellaOps.Policy.Engine`, Scheduler | Join SBOM inventory with raw advisories/VEX, evaluate policies, issue `effective_finding_*` overlays, drive remediation workflows. | Writing to raw collections; bypassing guard scopes; running without recorded provenance. |
| **Experience layers** | Console, CLI, Exporters | Surface raw facts + policy overlays; run `stella aoc verify`; render AOC dashboards and reports. | Accepting ingestion payloads that lack provenance or violate guard results. |

### 2.2 Raw stores

| Collection | Purpose | Key fields | Notes |
|------------|---------|------------|-------|
| `advisory_raw` | Immutable vendor/ecosystem advisory documents. | `_id`, `tenant`, `source.*`, `upstream.*`, `content.raw`, `linkset`, `supersedes`. | Idempotent by `(source.vendor, upstream.upstream_id, upstream.content_hash)`. |
| `vex_raw` | Immutable vendor VEX statements. | Mirrors `advisory_raw`; `identifiers.statements` summarises affected components. | Maintains supersedes chain identical to advisory flow. |
| Change streams (`advisory_raw_stream`, `vex_raw_stream`) | Feed Policy Engine and Scheduler. | `operationType`, `documentKey`, `fullDocument`, `tenant`, `traceId`. | Scope filtered per tenant before delivery. |

### 2.3 Guarded ingestion sequence

```mermaid
sequenceDiagram
    participant Upstream as Upstream Source
    participant Connector as Concelier/Excititor Connector
    participant Guard as AOCWriteGuard
    participant Mongo as MongoDB (advisory_raw / vex_raw)
    participant Stream as Change Stream
    participant Policy as Policy Engine

    Upstream-->>Connector: CSAF / OSV / VEX document
    Connector->>Connector: Normalize transport, compute content_hash
    Connector->>Guard: Candidate raw doc (source + upstream + content + linkset)
    Guard-->>Connector: ERR_AOC_00x on violation
    Guard->>Mongo: Append immutable document (with tenant & supersedes)
    Mongo-->>Stream: Change event (tenant scoped)
    Stream->>Policy: Raw delta payload
    Policy->>Policy: Evaluate policies, compute effective findings
```

---

### 2.4 Authority scopes & tenancy

| Scope | Holder | Purpose | Notes |
|-------|--------|---------|-------|
| `advisory:ingest` / `vex:ingest` | Concelier / Excititor collectors | Append raw documents through ingestion endpoints. | Paired with tenant claims; requests without tenant are rejected. |
| `advisory:read` / `vex:read` | DevOps verify identity, CLI | Run `stella aoc verify` or call `/aoc/verify`. | Read-only; cannot mutate raw docs. |
| `effective:write` | Policy Engine | Materialise `effective_finding_*` overlays. | Only Policy Engine identity may hold; ingestion contexts receive `ERR_AOC_006` if they attempt. |
| `findings:read` | Console, CLI, exports | Consume derived findings. | Enforced by Gateway and downstream services. |

---

## 3 · Data & control flow highlights

1. **Ingestion:** Concelier / Excititor connectors fetch upstream documents, compute linksets, and hand payloads to `AOCWriteGuard`. Guards validate schema, provenance, forbidden fields, supersedes pointers, and append-only rules before writing to Mongo.
2. **Verification:** `stella aoc verify` (CLI/CI) and `/aoc/verify` endpoints replay guard checks against stored documents, mapping `ERR_AOC_00x` codes to exit codes for automation.
3. **Policy evaluation:** Mongo change streams deliver tenant-scoped raw deltas. Policy Engine joins SBOM inventory (via BOM Index), executes deterministic policies, writes overlays, and emits events to Scheduler/Notify.
4. **Experience surfaces:** Console renders an AOC dashboard showing ingestion latency, guard violations, and supersedes depth. CLI exposes raw-document fetch helpers for auditing. Offline Kit bundles raw collections alongside guard configs to keep air-gapped installs verifiable.
5. **Observability:** All services emit `ingestion_write_total`, `aoc_violation_total{code}`, `ingestion_latency_seconds`, and trace spans `ingest.fetch`, `ingest.transform`, `ingest.write`, `aoc.guard`. Logs correlate via `traceId`, `tenant`, `source.vendor`, and `content_hash`.

---

## 4 · Offline & disaster readiness

- **Offline Kit:** Packages raw Mongo snapshots (`advisory_raw`, `vex_raw`) plus guard configuration and CLI verifier binaries so air-gapped sites can re-run AOC checks before promotion.
- **Recovery:** Supersedes chains allow rollback to prior revisions without mutating documents. Disaster exercises must rehearse restoring from snapshot, replaying change streams into Policy Engine, and re-validating guard compliance.
- **Migration:** Legacy normalised fields are moved to temporary views during cutover; ingestion runtime removes writes once guard-enforced path is live (see [Migration playbook](../ingestion/aggregation-only-contract.md#8-migration-playbook)).

---

## 5 · References

- [Aggregation-Only Contract reference](../ingestion/aggregation-only-contract.md)
- [Concelier architecture](../ARCHITECTURE_CONCELIER.md)
- [Excititor architecture](../ARCHITECTURE_EXCITITOR.md)
- [Policy Engine architecture](policy-engine.md)
- [Authority service](../ARCHITECTURE_AUTHORITY.md)
- [Observability standards (upcoming)](../observability/policy.md) – interim reference for telemetry naming.

---

## 6 · Compliance checklist

- [ ] AOC guard enabled for all Concelier and Excititor write paths in production.
- [ ] Mongo schema validators deployed for `advisory_raw` and `vex_raw`; change streams scoped per tenant.
- [ ] Authority scopes (`advisory:*`, `vex:*`, `effective:*`) configured in Gateway and validated via integration tests.
- [ ] `stella aoc verify` wired into CI/CD pipelines with seeded violation fixtures.
- [ ] Console AOC dashboard and CLI documentation reference the new ingestion contract.
- [ ] Offline Kit bundles include guard configs, verifier tooling, and documentation updates.
- [ ] Observability dashboards include violation, latency, and supersedes depth metrics with alert thresholds.

---

*Last updated: 2025-10-26 (Sprint 19).*