walker+completion: surface list trailing-optionals + identifiers-first ordering (ADR-0022 Amendment 2)

walk_repeated discarded the last matched item's trailing-optional
expectations at a clean item boundary, so a comma-separated list
offered no continuation after a complete item: `order by Name `
gave no asc/desc, `select Name ` no `as`, `create table …
Code(text) ` no not/unique/default/check. Capture the last item's
skipped set and surface it when the list ends at an item boundary
(the separator `,` itself is deliberately not surfaced).

That fix made expression-position candidate lists long, which
exposed a visibility problem: the hint panel's candidate line is
single-row and window-scrolls on overflow, centring on item 0 when
nothing is selected — so with keywords-first, schema identifiers
scrolled off behind the `>` marker. Reverse the ordering: schema
identifiers (table/column/relationship names) now sort before
keywords, since a name the user would have to look up is the
highest-value completion and must stay visible (keywords are
learned over time; the tok_identifier/tok_keyword colour split
marks the boundary). This reverses the handoff-14 keywords-first
call, now recorded in ADR-0022 Amendment 2.

Tests: walker expected-set + completion-layer regressions for the
trailing-optionals and the ordering; candidate_ordering.rs header
invariant inverted; ~20 typing-surface snapshots re-baselined; a
two-line hint box recorded as a deferred follow-up.

docs/adr/0022-ambient-typing-assistance.md

@@ -480,6 +480,75 @@ re-baseline those snapshots. New snapshots cover:
 The snapshots are the regression net for "did we change the
 visual output unexpectedly".
 
+## Amendment 2 — Candidate ordering: schema identifiers before keywords (2026-05-21)
+
+This amendment **reverses the candidate-ordering call made in the
+handoff-14 ranker discussion** (keywords before schema
+identifiers). That call was never recorded in an ADR — it lived
+only in `tests/typing_surface/candidate_ordering.rs` — so this
+amendment also gives the ordering a decision record.
+
+### The obsolete premise
+
+Handoff-14 ordered command-part keywords before schema
+identifiers on the rationale that "grammar parts are read before
+the content that fills them," so `add column to table T` reads in
+order. That held while candidate lists were short. The SQL surface
+(ADR-0030/0031/0032/0033) made lists long — an expression position
+such as `where Name ` or `order by ` legitimately offers the
+column names *plus* the full expression-continuation keyword run
+(`is not like between in and or`, plus `asc`/`desc` in ORDER BY).
+
+The hint panel's candidate line is **single-row and
+window-scrolled** (`render_candidate_line`): when it overflows it
+centres on the selected item, or on item 0 when nothing is
+selected (the ambient, just-typed state). With keywords first, the
+schema identifiers sat at the tail and scrolled off behind the `>`
+marker — invisible until the user Tab-cycled to them.
+
+### The decision
+
+Schema identifiers (table / column / relationship names) now sort
+**before** keywords in the candidate list. A name the user would
+otherwise have to look up is the highest-value completion —
+valuable even to experts, who come to know the keywords over time —
+so it must stay visible by default. Within each section the prior
+rules are unchanged: identifiers alphabetised; keywords in
+grammar-declaration order (`to` before `table`); then type names,
+composite literals, branching punct, flags. The existing colour
+split (`tok_identifier` teal vs `tok_keyword` purple, §colour)
+makes the section boundary legible once both are on screen.
+
+### Related fix — Repeated trailing optionals
+
+This amendment shipped alongside a `walk_repeated` fix: a
+comma-separated list (`Repeated`) was discarding the last matched
+item's trailing-optional expectations at a clean item boundary, so
+`order by Name ` offered no `asc`/`desc`, `select Name ` no `as`,
+and `create table … Code(text) ` no `not`/`unique`/`default`/
+`check`. Those now surface (the separator `,` itself is
+deliberately not surfaced). This is what made identifier
+visibility pressing — the lists these positions produce are now
+both correct and long.
+
+### Deferred — two-line hint box
+
+As hint lists grow, a **two-line candidate box** (more candidates
+visible without scrolling) is worth considering. Deferred for now
+on screen-space grounds; recorded so it is not lost.
+
+### Coverage
+
+`tests/typing_surface/candidate_ordering.rs` rewritten to assert
+identifiers precede keywords (header invariant #2 inverted; the
+`to`-before-`table` keyword-order invariant #1 retained).
+`completion::tests::identifiers_come_before_keywords_in_grammar_order`
+and `identifiers_precede_keywords_at_expression_position` lock the
+ordering; `order_by_after_sort_item_offers_direction`,
+`projection_after_item_offers_alias_keyword`, and
+`create_table_after_column_spec_offers_constraints` lock the
+trailing-optional fix. ~20 typing-surface snapshots re-baselined.
+
 ## Out of scope
 
 Deliberately deferred to keep this ADR shippable as a single