#1830: require exporter support before skipping duplicate frames

docs/agents.md

@@ -322,7 +322,8 @@ build real projects through these interfaces; they are worked examples of everyt
   **A render never writes one file twice either:** when two outputs of the job (two items, a
   `renderQueue.duplicate` copy, output modules, segments) name the same file, the whole render is
   refused before anything is written, naming both items. Sequences clash only on frames both
-  write, and a later item with Skip Existing Files leaves the earlier one's frames alone. Default
+  write. A later item with Skip Existing Files leaves the earlier one's frames alone only when
+  the exporter can check existing files; browser and other memory sinks still report collisions. Default
   names are numbered like footage collisions when another queue item writes them
   (`renderQueue.add`, `render.preRender`, `comp.saveFrameAs {queue}`, `file.createProxy`: a second
   `Main` renders to `Main_1.mp4`); a name you give is kept, and `renderQueue.duplicate` copies the

docs/mcp.md

@@ -58,8 +58,9 @@ receive `resultType: complete` and list/read cache hints; document reads are nev
 Two outputs of one job that write the same file (two items with one Output To, a duplicated item,
 output modules or segments that meet) refuse the whole `renderQueue.render` before anything is
 written: the reply is `isError: true`, naming both items, and the queue is left as it was.
-Sequences clash only on the frames both write, and an item with Skip Existing Files leaves the
-earlier one's frames alone. A new item's default output name is numbered (`Main.mp4`,
+Sequences clash only on the frames both write. Skip Existing Files leaves earlier frames alone
+only when the exporter can check existing files; browser and other memory sinks still report
+collisions. A new item's default output name is numbered (`Main.mp4`,
 `Main_1.mp4`) when another item of the queue writes it.
 
 ## Progress and cancellation