The installer's ensure_fts5() handled a no-FTS5 Python by running
'uv python install --reinstall', but WHICH Python builds a uv can
install is baked into the uv binary's download manifest. A stale uv
(e.g. 'pip install uv==0.7.20', which predates python-build-standalone
#694) only knows about pre-FTS5 builds, so --reinstall just pulls the
same FTS5-less interpreter — a no-op for FTS5. Result: 'Could not obtain
an FTS5-capable Python' and a broken session search even on the
supported installer path.
ensure_fts5() now escalates uv itself: reinstall with current uv ->
'uv self update' + reinstall (stale standalone uv) -> install a fresh
standalone uv into a temp dir and reinstall with that (externally-managed
uv that can't self-update, the reported case). Pythons live in uv's
shared store, so the fresh uv's --reinstall overwrites the stale
interpreter in place and the installer's later 'uv python find' resolves
to the FTS5-capable build.
Verified against the reporter's exact repro (ubuntu:24.04 +
pip install uv==0.7.20): Python 3.11.13 (no FTS5) -> 3.11.15 (FTS5).
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