# Decision 0004: Model Switching Boundaries

Status: Accepted
Date: 2026-05-03

## Context

The model browser can show image, video, 3D, and audio models. A selected generation node has a fixed node type and data shape.

Switching a selected image node to a video model would require replacing the node type and data contract.

## Decision

Node-edit mode allows same-capability model switching only.

Rules:

- Image node model browser filters to image models.
- Video node model browser filters to video models.
- 3D/audio follow the same rule when adapters exist.
- Cross-capability switching is blocked in node-edit mode.
- Empty-create mode may select any capability because there is no existing node shape.
- Same-capability switching preserves common fields and clears provider-specific `parameters`, `fallbackParameters`, and `inputSchema`.

## Rationale

Changing model capability is a graph-structure decision, not just a parameter edit. The canvas should express that decision by creating a new node type.

## Consequences

- Model dialog filters are part of correctness, not just convenience.
- Composer adapters must validate selected model capability before writing to a node.
- Tests must verify image nodes cannot receive video models through the composer.