The Gemara in Yevamot 5oa clearly assumes that R. Yehuda Hanassi authored the Mishna:
אמר רב יוסף כאן שנה רבי משנה שאינה צריכה
Are there any tannaic sources that also state that he authored the Mishna (e.g. a Tosefta, that is an actual tannaic source, not an Ammoraic source referencing tannaim)?
I am aware that there is debate regarding his role in the authorship. My question isn't whether he authored, compiled, or redacted. My question is only whether there is a tannaic source for any of the above.
EDIT: In order of priority to answering the question:
- A Tannaic source.
- Some proof that there is no Tannaic source (ignorance being a poor proof).
- A distant third: a very thorough analysis on Rabbi Yehudah HaNassi's role in compiling the Mishnah.