In advanced mode an entry word like `create`/`drop` has several candidate
nodes (the SQL forms + the DSL fallback), but the walker commits to one,
so completion offered only that node's continuations — `drop ` showed
just `table`, and `drop rel` dead-ended at an empty list even though the
DSL drops parse via fallback.
At the entry-word boundary (advanced mode), walk every candidate, keep the
viable (Incomplete) ones, and union their next-keyword continuations:
`drop ` → table·index·column·relationship·constraint; `drop rel` →
relationship; `create ` → table·unique·index. Deeper positions keep the
committed walk untouched (no change to insert/update/delete/select).
Each continuation is classified by producing category (Both/Advanced/
Simple) and block-ordered Both → Advanced → Simple, so they read as
contiguous groups (the foundation for the 4i(e) colour, landing next).
CompletionProbe carries a parallel expected_modes; the parse path is
unchanged (the merge is completion-only).
Tests: completion merge + partial + block-order cases; the two tests that
encoded the old single-node behaviour updated. Full suite 1911 passing /
0 failing / 1 ignored; clippy clean.
claude@clouddev1