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AOSP stopped reviewing in public, and it takes the language-matched arm with it

# research(2026-09). The gate compares an OpenStack adapter against a Qt one. The two organizations barely share a file type, so an adapter that learned nothing but the language would beat the other's on its own held-out data and pass. The window reports now carry the histogram the variables table promised: OpenStack's training window is 2,054 Python and 1,184 reStructuredText of 4,327; Qt's is 4,211 C++, 1,427 qdoc and 807 headers of 8,442. In the dev window Qt holds eight Python examples against OpenStack's 243, so the matched arm cannot be evaluated on this pair at all.

AOSP was the obvious fix, already fetched, C++ like Qt. It is not available, and the reason is upstream rather than ours.

months merged changes fetched per month examples built
2024-11 to 2025-03 684 to 964 207 to 450
2025-04 to 2025-10 26 to 63 0 to 6

aosp-main became read-only on 2025-03-27 and all Android development moved to Google's internal branches; external contributions still reach the public Gerrit, which is the residue the later months show. The cliff in our own corpus sits exactly there, and it was measured before the cause was looked up.

What it costs, in three places.

  1. RQ1 cannot use AOSP as a third arm. Its dev window holds three examples. No widening of the project list fixes a review process that stopped: the ten projects fetched average one to six examples a month since April 2025.
  2. RQ2's AOSP results rest entirely on the period before the change. They were built with --window all and are unaffected as measurements, but the organization they describe no longer reviews in public at that volume, and the study should say so rather than let a reader assume the corpus could be extended.
  3. The sealed test window would be nearly empty for AOSP, so this is permanent, not a gap to wait out.

What is still available. Probed directly, three public Gerrit hosts answer and are busy in the dev window's own months, each returning a full page of merged changes with more behind it where AOSP returned 43 for the month: Chromium (chromium/src dominant, C++), Fuchsia (C++) and Go. Of the three, Chromium is the natural language-matched partner for Qt on size and language. Whether a review culture yields anchored inline comments at a usable rate is a separate question that only a build answers, and AOSP's own drop counts are the warning: 15,880 author comments and 7,305 unanchored hunks against 5,133 usable examples. Adding a host is also a corpus-scope decision that touches the ethics determination, so it is recorded here rather than taken.