docs(compose): say what a clip does past the end of its file

jobs/compose/reference/timeline.mdx

@@ -48,7 +48,7 @@ The shape of a compose request, from the outside in. Each asset kind adds its ow
 | `overlays` | object[] | Clips composited over the WHOLE video regardless of scenes: a logo, a watermark, a persistent title. The whole video is their container, so omitting `length` spans it. `start` defaults to 0. |
 | `overlays.asset` * | object |  |
 | `overlays.start` | number | When the clip begins, in seconds from the start of the video. Omit it and the clip starts after everything already placed on its track, pulled back by any transition sitting immediately before it. The first clip on a track starts at 0. min 0. |
-| `overlays.length` | number \| `"end"` | How long the clip plays. Omit it and the clip runs as long as its CONTENT does: the trim span, the source duration divided by speed, or a composition's own end. Use "end" and it runs to the end of the video instead, whatever the source says, which is what a music bed wants. Text and images have no duration of their own, so omitting is the same as "end" for them and a title with no length stays up. A clip that runs to the end must be the last on its track. |
+| `overlays.length` | number \| `"end"` | How long the clip plays. Omit it and the clip runs as long as its CONTENT does: the trim span, the source duration divided by speed, or a composition's own end. Use "end" and it runs to the end of the video instead, whatever the source says, which is what a music bed wants. Text and images have no duration of their own, so omitting is the same as "end" for them and a title with no length stays up. A clip that runs to the end must be the last on its track. A video, audio or animation clip that runs past the end of its file holds the last frame, silent, until the clip ends, and the job says which clip in the render step's `clipOverruns`. |
 | `overlays.opacity` | number \| object[] | Clip opacity: a constant 0..1, or keyframes [\{time, value, easing\}] for animated fades. Fade a clip in with [\{time:0,value:0\},\{time:1,value:1\}]. default `1`. |
 | `overlays.transform` | object | Position/scale/rotate the clip within the frame (picture-in-picture, Ken Burns). Omit for full-frame. |
 | `overlays.crop` | object | Trim edges off the frame by percent; the kept region scales back up to fill. Use to reframe landscape footage for a vertical canvas, and `radius` to round its corners. |
@@ -73,7 +73,7 @@ Every clip takes these, whatever its asset.
 | Field | Type | What it does |
 | --- | --- | --- |
 | `start` | number | When the clip begins, in seconds from the start of the video. Omit it and the clip starts after everything already placed on its track, pulled back by any transition sitting immediately before it. The first clip on a track starts at 0. min 0. |
-| `length` | number \| `"end"` | How long the clip plays. Omit it and the clip runs as long as its CONTENT does: the trim span, the source duration divided by speed, or a composition's own end. Use "end" and it runs to the end of the video instead, whatever the source says, which is what a music bed wants. Text and images have no duration of their own, so omitting is the same as "end" for them and a title with no length stays up. A clip that runs to the end must be the last on its track. |
+| `length` | number \| `"end"` | How long the clip plays. Omit it and the clip runs as long as its CONTENT does: the trim span, the source duration divided by speed, or a composition's own end. Use "end" and it runs to the end of the video instead, whatever the source says, which is what a music bed wants. Text and images have no duration of their own, so omitting is the same as "end" for them and a title with no length stays up. A clip that runs to the end must be the last on its track. A video, audio or animation clip that runs past the end of its file holds the last frame, silent, until the clip ends, and the job says which clip in the render step's `clipOverruns`. |
 | `opacity` | number \| object[] | Clip opacity: a constant 0..1, or keyframes [\{time, value, easing\}] for animated fades. Fade a clip in with [\{time:0,value:0\},\{time:1,value:1\}]. default `1`. |
 | `transform` | object | Position/scale/rotate the clip within the frame (picture-in-picture, Ken Burns). Omit for full-frame. |
 | `transform.position` | object \| object[] | Where to place the clip, in pixels like \{x:1600,y:900\} or percent like \{x:"75%",y:"75%"\}, or keyframes of them to move it. Omit it and the clip is centred, so a scale of 0.5 alone is a centred picture-in-picture. |