walker: 3a — category-grouped mode-aware dispatch (ADR-0033 Amendment 1)

Replaces ADR-0033 §2's original Node::Guard + Choice(SQL,DSL) mechanism,
which was found during 3a to be unworkable: any guard-in-Choice approach
forces a walk_choice change (walk_choice falls through only on NoMatch, so
simple-mode valid-DSL would wrongly surface "this is SQL"), and walk_seq
treats a NoMatch past idx 0 as a hard Failed, breaking advanced-mode DSL
fall-through.

Mechanism (Amendment 1): each REGISTRY entry is tagged
CommandCategory::{Simple, Advanced}, generalising the whole-command
is_advanced_only gate. walk() becomes a thin dispatcher over decide()
(mode-aware candidate selection: simple commits the DSL node or emits the
"this is SQL" hint; advanced tries SQL first, DSL as a full-line fallback)
and an extracted walk_one_command(); speculative match-testing runs on a
scratch WalkContext so the caller's context is only touched by the
committed walk. No Node::Guard, no walk_choice/walk_seq change.

6 dispatch smoke tests on a shared-entry-word smoke registry; 1446 baseline
green; clippy clean.

docs/adr/README.md

@@ -38,4 +38,4 @@ This directory contains the project's ADRs, recorded per
 - [ADR-0030 — Advanced mode: the standard-SQL surface](0030-advanced-mode-sql-surface.md) — **Accepted**, SQL added as grammar *within the unified grammar tree* (ADR-0024), not a separate batch parser — so SQL gets the same completion / highlighting / hints / parse-errors as the DSL; mode gates the SQL forms; DDL routes through the typed `Command` executor (metadata + type vocabulary preserved), DML and `SELECT` execute as validated SQL; engine-neutral posture, the DSL→SQL teaching echo; supersedes ADR-0001's `sqlparser-rs` reservation; phased plan (`Q1` / `Q2` / `Q4`)
 - [ADR-0031 — The SQL expression grammar](0031-sql-expression-grammar.md) — **Accepted**, the stratified SQL expression grammar fragment commissioned by ADR-0030 §3: a single precedence ladder (`OR`/`AND`/`NOT`, the comparison/`LIKE`/`IN`/`BETWEEN`/`IS NULL` predicate set, arithmetic incl. `||`, function calls, `CASE`) — the superset of ADR-0026's DSL `WHERE` grammar, authored as a parallel fragment so simple mode is untouched; pure validation, builds **no** AST (consumers run/store SQL as text per ADR-0030 §4/§6); reuses ADR-0026's `Subgrammar` recursion + depth cap unchanged; subquery expressions and qualified column refs deferred to ADR-0030 Phase 2
 - [ADR-0032 — The full SQL `SELECT` grammar](0032-sql-select-grammar.md) — **Accepted**, the Phase-2 grammar commissioned by ADR-0030 §3: full `SELECT` with `INNER`/`LEFT`/`RIGHT`/`FULL OUTER`/`CROSS` joins, `GROUP BY`/`HAVING`, all four set ops (`UNION`/`UNION ALL`/`INTERSECT`/`EXCEPT`), `WITH` and `WITH RECURSIVE` CTEs, `LIMIT … OFFSET`, `DISTINCT`, `t.*`, and bare-alias projection (lifting Phase-1 §4.2); additive extensions to ADR-0031's `sql_expr` for scalar subqueries, `IN (SELECT …)`, `[NOT] EXISTS`, and qualified column refs (redeeming ADR-0031 §7 OOS-1/OOS-2); grammar-recursion via `Subgrammar(&SQL_SELECT_COMPOUND)` reuses ADR-0026's `MAX_SUBGRAMMAR_DEPTH = 64` cap unchanged; **softens ADR-0030 §8's "ambient assistance comes for free" claim**: completion scope needs new `WalkContext` accumulators (a `from_scope_stack` of `ScopeFrame`s holding `from_scope` / `cte_bindings` / `projection_aliases`), a **new walker node variant `Node::ScopedSubgrammar(&Node)`** as the push/pop trigger (existing `Node::Subgrammar` unchanged so DSL `Expr` and `sql_expr` recursion are unaffected), qualified-prefix completion narrowing, body-projection-derived CTE column resolution (so `SELECT *` and explicit-projection CTE bodies both yield real column completion past `cte_alias.|`), and a **post-walk fixup pass** that re-resolves projection-list identifier highlighting/validity once `FROM` is parsed (the projection-before-FROM problem); classifies every Phase-2 validation case against ADR-0027's ERROR/WARNING guideline (§11): five new `diagnostic.*` keys for parse-time-detectable cases (unknown qualifier, ambiguous column, projection-alias misplaced, CTE/compound arity mismatch) plus eight `engine.*` translation keys; a MatchedPath-walking predicate-warnings variant that closes the Phase-1 gap where SQL `WHERE` expressions emitted no `LIKE`-on-numeric / `= NULL` / type-mismatch warnings (ADR-0027 Amendment 1 finally extends to the SQL surface); adds a worker-side post-prepare type-resolution pass via engine column-origin metadata so bare column refs recover their playground type (partially lifting Phase-1 §4.5, the bool→0/1 case) — `Cargo.toml` gains `column_metadata` to rusqlite features (verified against pinned 0.39.0); `__rdbms_*` rejection extended to every new table-source slot; Amendment 1 narrows §12's resolution rule from a grammar-side structural classification to "trust the engine's column-origin metadata verbatim" after an empirical probe showed origin metadata follows through non-recursive CTEs, scalar subqueries, derived tables, set ops, and joins — the one structural exception is recursive CTE result columns, which return None and stay typeless; Amendment 2 records that §10.6's "rewrite the highlight class" prescription is realised via the two-pass schema-existence diagnostic + the renderer's diagnostic-overlay path (no separate per-byte rewrite step needed; no new HighlightClass variant), and that the projection-before-FROM completion narrowing has been improved by an `src/completion.rs` look-ahead probe when the leading walk's `from_scope` is empty but the full input parses
-- [ADR-0033 — The full SQL DML grammar (`INSERT` / `UPDATE` / `DELETE`)](0033-sql-dml-grammar.md) — **Proposed**, the Phase-3 grammar commissioned by ADR-0030 §3: single- and multi-row `INSERT` (incl. `INSERT … SELECT` recursing through ADR-0032's `SQL_SELECT_COMPOUND`), `UPDATE` with `SET` assignment list, `DELETE`, all three optionally followed by `RETURNING projection_list`, plus full `ON CONFLICT … DO NOTHING / DO UPDATE` UPSERT on INSERT; **fixes the DSL-vs-SQL dispatch architecture for shared entry words (`insert`/`update`/`delete`)**: SQL-first / DSL-fallback in Advanced mode via a `Choice(SQL_shape, DSL_shape)` per shape, gated by a new walker capability `Node::Guard(fn)` — a zero-byte-consumption gating node that fails the enclosing Seq with a `ValidationError`; carries `Command::SqlInsert` / `SqlUpdate` / `SqlDelete` variants and `do_sql_*` worker handlers each of which knows the target table (for re-persistence) and the `returning: bool` flag (for DataResult routing); `shortid` auto-fill mirrors the DSL `do_insert` mechanism via worker post-fill; SQL DELETE produces the same per-relationship cascade summary the DSL DELETE does (ADR-0014 parity), with the WHERE-clause source bytes re-injected into per-child pre-count subqueries; three new walker diagnostics (`insert_arity_mismatch` ERROR, `auto_column_overridden` WARNING, `not_null_missing` WARNING) with positive + negative tests each; OOS list explicitly carves out `DEFAULT VALUES` (the project's planned seed feature), SQLite-specific `OR REPLACE` / `OR IGNORE` / `OR ABORT` / `OR FAIL` / `OR ROLLBACK` prefixes, `UPDATE FROM` multi-table updates, and WITH-prefixed DML; the `excluded` keyword inside `ON CONFLICT DO UPDATE` is a deliberate carve-out from ADR-0030 §7's engine-neutral posture (no standard-SQL UPSERT spelling exists that SQLite and PostgreSQL share); eleven phased sub-phases each with explicit exit gates + written DA gate, opening with `Node::Guard` mechanism scaffolding before any DML grammar lands; initial DA review recorded seven critiques that were resolved before status moved to Proposed
+- [ADR-0033 — The full SQL DML grammar (`INSERT` / `UPDATE` / `DELETE`)](0033-sql-dml-grammar.md) — **Proposed**, the Phase-3 grammar commissioned by ADR-0030 §3: single- and multi-row `INSERT` (incl. `INSERT … SELECT` recursing through ADR-0032's `SQL_SELECT_COMPOUND`), `UPDATE` with `SET` assignment list, `DELETE`, all three optionally followed by `RETURNING projection_list`, plus full `ON CONFLICT … DO NOTHING / DO UPDATE` UPSERT on INSERT; **fixes the DSL-vs-SQL dispatch architecture for shared entry words (`insert`/`update`/`delete`)**: SQL-first / DSL-fallback in Advanced mode via a `Choice(SQL_shape, DSL_shape)` per shape, gated by a new walker capability `Node::Guard(fn)` — a zero-byte-consumption gating node that fails the enclosing Seq with a `ValidationError`; carries `Command::SqlInsert` / `SqlUpdate` / `SqlDelete` variants and `do_sql_*` worker handlers each of which knows the target table (for re-persistence) and the `returning: bool` flag (for DataResult routing); `shortid` auto-fill mirrors the DSL `do_insert` mechanism via worker post-fill; SQL DELETE produces the same per-relationship cascade summary the DSL DELETE does (ADR-0014 parity), with the WHERE-clause source bytes re-injected into per-child pre-count subqueries; three new walker diagnostics (`insert_arity_mismatch` ERROR, `auto_column_overridden` WARNING, `not_null_missing` WARNING) with positive + negative tests each; OOS list explicitly carves out `DEFAULT VALUES` (the project's planned seed feature), SQLite-specific `OR REPLACE` / `OR IGNORE` / `OR ABORT` / `OR FAIL` / `OR ROLLBACK` prefixes, `UPDATE FROM` multi-table updates, and WITH-prefixed DML; the `excluded` keyword inside `ON CONFLICT DO UPDATE` is a deliberate carve-out from ADR-0030 §7's engine-neutral posture (no standard-SQL UPSERT spelling exists that SQLite and PostgreSQL share); eleven phased sub-phases each with explicit exit gates + written DA gate, opening with the dispatch mechanism before any DML grammar lands; initial DA review recorded seven critiques that were resolved before status moved to Proposed; **Amendment 1 supersedes §2's dispatch mechanism**: the originally-chosen `Node::Guard(fn)` + `Choice(SQL_shape, DSL_shape)` was found during 3a to be unworkable as framed (any guard-in-`Choice` mechanism forces a `walk_choice` change — `walk_choice` only falls through on `NoMatch`, so Simple-mode valid-DSL would wrongly surface "this is SQL", and `walk_seq` treats a `NoMatch` past `idx 0` as a hard `Failed`, breaking Advanced-mode DSL fall-through); replaced by **category-grouped, mode-aware dispatch** in `walker::walk` (each `REGISTRY` entry tagged `CommandCategory::{Simple, Advanced}`, generalising the existing whole-command `is_advanced_only` gate), shared entry words carrying a node in both groups, no `Node::Guard` and no `walk_choice`/`walk_seq` change, advanced-mode completion SQL-first with DSL as a full-line fallback