> ## 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.

# SEV: Symphony Evolution Vector for Planned Changes

> SEV evaluates planned changes, novelty, and lifecycle transitions with deterministic cases, dependency-ready sets, disposable graphs, and non-applying recovery advice.

The Symphony Evolution Vector (SEV) owns planned-change and encountered-novelty cases across the platform. Its engine is a freezing-path, read-only C++26 process. SEV neither watches a host nor applies a transition; it produces evidence and disposition advice.

## Operations

* **Case evaluation**: deterministic evolution cases for additions, changes, renames, supersessions, deprecations, retirements, and removals.
* **Impact and disposition planning**: assign each case to its authoritative owners.
* **Dependency-ready-set recalculation**: derive the safe order of dependent transitions.
* **Transition verification**: confirm the observed state after a transition matches its expected shape.
* **Recovery advice**: describe safe forward or reverse steps when a transition is interrupted.
* **SCSEV assessment**: the first governed SEV profile applies these operations to documentation-only knowledge-surface evolution.
* **Novelty and watch checks**: detect new or unexpected surfaces for reviewer attention.
* **Trigger coalescing** and **lifecycle-session binding**: reduce duplicate evaluation and bind cases to a session.
* **Graph projection**: disposable graphs for review.

## SCSEV profile

SCSEV reuses SSFV feature administration, stable qxctl command truth, and engine-operation descriptors. It does not create a duplicate engine or registry. The first engine slice is report-only and proposal-only; durable external action remains separately authorized through qxctl and the knowledge session coordinator.

<Note>
  SEV is read, query, validate, and propose only. Canonical apply remains disabled across the SKV engine family.
</Note>

## Related surfaces

<CardGroup cols={2}>
  <Card title="SKV overview" icon="book-open" href="/symphony/symphony/skv/overview">
    The umbrella framework and Contract Quad model.
  </Card>

  <Card title="SSFV" icon="list-check" href="/symphony/symphony/skv/ssfv">
    Feature administration reused by the SCSEV profile.
  </Card>

  <Card title="SAV" icon="scale-balanced" href="/symphony/symphony/skv/sav">
    Composition and compatibility evaluation for changed components.
  </Card>

  <Card title="qxctl vector commands" icon="terminal" href="/symphony/symphony/qxctl/vector-commands">
    Ratified evolution grammar arrives as `qxctl evolution ...` once implemented.
  </Card>
</CardGroup>


## Related topics

- [SCLV: Symphony Change Ledger Vector for Source Changes](/symphony/symphony/skv/sclv.md)
- [Symphony Architecture](/symphony/symphony/concepts/architecture.md)
- [SSFV: Symphony Semantic Feature Vector and Registry](/symphony/symphony/skv/ssfv.md)
- [SAV: Symphony Accordare Vector for Composition Evaluation](/symphony/symphony/skv/sav.md)
- [Symphony Knowledge Vector: SKV Framework Overview](/symphony/symphony/skv/overview.md)