> ## Documentation Index
> Fetch the complete documentation index at: https://docs.quanux.org/symphony/llms.txt
> Use this file to discover all available pages before exploring further.

# Symphony Vector Engines: Independent Installation Overview

> Every Symphony vector engine installs independently, runs out-of-process in C++, and stays authority-free. Meet the SKV, SCV, and SHV engine families here.

Every active application-level Symphony vector may have an independently installable, out-of-process C++ engine. Shared authority-free C++ mechanics live under `libraries/`; a separate C++ coordinator owns authenticated-session and worktree-reconciliation mechanics. Engines inspect, validate, project, and propose within vector-owned contracts. They do not acquire authority merely by generating content.

## Implemented engines

<CardGroup cols={2}>
  <Card title="Knowledge Vector foundation" icon="cube" href="/symphony/symphony/engines/knowledge-vector-foundation">
    C++ process framing, JSON, SHA-256, snapshots, receipts, and manifest discovery.
  </Card>

  <Card title="Session coordinator" icon="gears" href="/symphony/symphony/engines/coordinator">
    Authenticated sessions, worktree reconciliation, and lifecycle apply coordination.
  </Card>

  <Card title="SCV source engines" icon="cloud" href="/symphony/symphony/engines/scv-source-engines">
    Eight C++26 SCV, hyperscaler, edge, and provider source-knowledge engines.
  </Card>

  <Card title="SHV engines" icon="microchip" href="/symphony/symphony/engines/shv-engines">
    Hardware source, catalogue, profile, partition, publication, and adapter engines.
  </Card>
</CardGroup>

## SKV engine family

The SKV surfaces each have their own engine:

* SKVI, SCLV, SACV, SODV, and SSFV engines each implement inspect, check, propose, project (and recovery where applicable).
* SAV and SEV engines are freezing-path C++26 processes for composition evaluation and evolution cases.

<Note>
  Every current SKV engine is read, query, validate, and propose only. Programmatic canonical apply remains disabled until each engine's SSIAG permission verification, expected-state transaction, qxctl safeguard, STAV event, recovery, and negative-test contracts are complete.
</Note>

## Common guarantees

* Independent installation and uninstallation per module
* No ambient repository crawl; manifest discovery is explicit
* No shared authority; every mutation route is gated by SSIAG plus STAV
* No hot-path residency; engines never inject latency into live workloads

## Related surfaces

<CardGroup cols={2}>
  <Card title="qxctl overview" icon="terminal" href="/symphony/symphony/qxctl/overview">
    Administrative CLI that invokes exact receipt-validated engines.
  </Card>

  <Card title="Maestro" icon="chalkboard-user" href="/symphony/symphony/governance/maestro">
    Records docking relationships between engines and receptors.
  </Card>
</CardGroup>


## Related topics

- [SKVI: The Symphony Knowledge Vector Index Engine](/symphony/symphony/skv/skvi.md)
- [qxctl validate: Symphony Validator Warning Policy](/symphony/symphony/qxctl/validate.md)
- [Maestro: Symphony Vector-Engine Presence Authority](/symphony/symphony/governance/maestro.md)
- [Symphony Architecture](/symphony/symphony/concepts/architecture.md)
- [Symphony Knowledge Vector: SKV Framework Overview](/symphony/symphony/skv/overview.md)