# V2 script grammar compatibility

This document describes the supported V2 plain-text import grammar. Current
Create authoring uses typed `CreateSnapshot` revisions and does not serialize
its editor state through this grammar.

The V2 bridge `flatToPayloads()` converts the grammar into `ScenePayload[]`.
Provider-specific payloads are derived later by render and integration
infrastructure; the browser never constructs them.

## Forms

| Form                   | Meaning                                    |
| ---------------------- | ------------------------------------------ |
| `@imageN <text>`       | Avatar speech anchored to image N          |
| `@imageN { <prompt> }` | Standalone generated video from image N    |
| `{ @imageN <prompt> }` | Overlay on the current avatar              |
| `{ <prompt> }`         | Continue from the preceding rendered frame |
| `@audioN`              | Uploaded audio on the current avatar       |

Plain text following an avatar line continues that avatar's speech. Video,
overlay and Continue forms may add `:D` after the closing brace to request a
duration. Advanced brace segments support `v:`, `n:`, `s:`, `an:`,
`am:auto|prompt|asset|off`, `ag:` and transition `tK`.

Whitespace and indentation do not change token meaning. Tags must begin a line
or appear at the start of a brace body; nested braces and inline image tags in
speech are invalid. Provider-specific prompt and duration limits are validated
before submission.

Legacy bare image lines remain parser-compatible for existing V2 projects, but
new generated V2 scripts should use the explicit forms above.

## Create boundary

Create visual blocks carry their own typed `visual_kind`, entry source,
timeline placement and media plan. In particular, Create Continue is an
independent visual block with `entry.mode = previous_exit`, an explicit
predecessor and the predecessor's accepted terminal-frame fingerprint. It is
not derived from the V2 brace syntax.