> ## 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 Architecture

> Understand the boundaries between user-selected infrastructure, vector contracts, engines, qxctl, and governed evidence.

Symphony separates user-selected infrastructure and workloads from platform knowledge and administration. The platform can inspect, validate, and report compatibility without claiming ownership of your strategy or treating a recommendation as a mandate.

## Physical and workload layer

A [Node](/symphony/symphony/concepts/node-habitat-nest) is an identified physical computer. A **Habitat** is its exact operating system and package conditioning, and a **Nest** is a workload serving a purpose selected by the user. Clusters connect Nodes through one or more buses. Bus fabrics, adapters, providers, and hardware choices are explicit rather than universal defaults.

The [hot path](/symphony/symphony/concepts/hot-path-isolation) stays separate from administrative residency. qxctl and knowledge-plane work may explicitly administer a Node, but they do not become hidden continuous dependencies of live execution.

## Semantic ownership

[Vectors](/symphony/symphony/concepts/vectors) are bounded, enduring owners of meaning and permitted operations. Each owner publishes a Contract Quad: `INTENT.md`, `MANIFEST.md`, `SKILL.md`, and `SPEC.md`. The [Symphony Knowledge Vector (SKV)](/symphony/symphony/skv/overview) indexes canonical surfaces and preserves a route to their owner. Companion schemas, registries, and ledgers remain governed without becoming extra members of the Quad.

Delivery phases describe when work is done. They do not transfer semantic ownership from one vector to another.

## Engines and command surface

[Vector engines](/symphony/symphony/engines/overview) are independently installable, out-of-process components that inspect, check, project, and propose within their owner contracts. They do not gain authority merely by producing a proposal.

[qxctl](/symphony/symphony/qxctl/overview) owns administrative command grammar and presentation. It invokes bounded, receipt-validated capabilities, while the vector that defines an operation retains its semantics. Authorization and audit evidence govern mutation routes; [caller classification](/symphony/symphony/concepts/caller-authority) alone grants no authority.

## Truth and evolution

Current contracts state current truth. The change and publication ledgers preserve the evidence recorded at a particular point in time. Disagreement among contracts, implementation evidence, and recorded history is surfaced as drift rather than silently rewritten. [SAV](/symphony/symphony/skv/sav) evaluates composition compatibility; [SEV](/symphony/symphony/skv/sev) plans governed evolution.

<Note>
  This overview is a map of boundaries. Consult each linked vector's current contract and implementation evidence before treating a capability as available in a specific installation.
</Note>


## Related topics

- [QuanuX Symphony Documentation](/symphony/symphony/index.md)
- [Quickstart: Explore QuanuX Symphony](/symphony/symphony/quickstart.md)
- [Symphony Quantitative Vector: Framework Contracts](/symphony/symphony/vectors/sqv.md)
- [Symphony Node Vector: Node Identity and Cluster Records](/symphony/symphony/vectors/snv.md)
- [Symphony Intelligence Vector: Future Agent Collaboration](/symphony/symphony/vectors/siv.md)