grammar+db: 3b — SQL INSERT grammar + minimal execution (ADR-0033 §1)

SQL_INSERT_SHAPE (INTO <table> [(cols)] VALUES tuple(s)) with __rdbms_*
target rejection; Command::SqlInsert{sql,target_table}; Request::RunSqlInsert
+ do_sql_insert worker (tx-guarded: execute, then finalize_persistence for
CSV + history before commit, so failures roll back and don't re-persist).
Auto-show is best-effort via last_insert_rowid range.

Isolated behind a dev `sqlinsert` entry word (Advanced) so the SQL path is
testable without making `insert` a shared word yet (that's 3j, after 3d
auto-fill parity). Command::SqlInsert carries only sql+target_table; the
plan's listed_columns/returning land in 3d/3g where they're read.

6 grammar accept/reject tests + 8 integration tests (single/multi-row,
column-list, full-arity, history, rollback-on-failure, multi-row atomicity,
parse-path reconstruction, internal-table rejection). 1452 baseline green.

src/dsl/grammar/data.rs

@@ -20,7 +20,7 @@ use crate::dsl::command::{Command, Expr, RowFilter};
 use crate::dsl::grammar::{
     CommandNode, IdentSource, Node, NumberValidator, ValidationError, Word, expr,
     shared::{column_value_list, current_column_value},
-    sql_select,
+    sql_insert, sql_select,
 };
 use crate::dsl::walker::context::WalkContext;
 use crate::dsl::value::Value;
@@ -855,6 +855,37 @@ fn build_select(_path: &MatchedPath, source: &str) -> Result<Command, Validation
     })
 }
 
+/// Build `Command::SqlInsert` from a validated SQL `INSERT`
+/// (ADR-0033 §1, sub-phase 3b). Extracts the target table from
+/// the matched path so the worker re-persists the right CSV.
+///
+/// Dev-scaffold detail: the entry word is `sqlinsert` (not valid
+/// SQL), so the statement is reconstructed as `insert` + the
+/// matched tail. Sub-phase 3j wires the real `insert` entry word,
+/// at which point this collapses to `source.trim()` like
+/// `build_select`.
+fn build_sql_insert(path: &MatchedPath, source: &str) -> Result<Command, ValidationError> {
+    let target_table = path
+        .items
+        .iter()
+        .find_map(|item| match item.kind {
+            MatchedKind::Ident {
+                role: "insert_target_table",
+                ..
+            } => Some(item.text.clone()),
+            _ => None,
+        })
+        .unwrap_or_default();
+    // Everything after the entry word is the `INTO …` tail; prefix
+    // the real `insert` keyword for the engine.
+    let tail = path
+        .items
+        .first()
+        .map_or(source, |entry| &source[entry.span.1..]);
+    let sql = format!("insert {}", tail.trim());
+    Ok(Command::SqlInsert { sql, target_table })
+}
+
 // =================================================================
 // CommandNodes
 // =================================================================
@@ -930,6 +961,24 @@ pub static WITH: CommandNode = CommandNode {
     help_id: None,
     usage_ids: &["parse.usage.select"],};
 
+/// SQL `INSERT` development scaffold (ADR-0033 sub-phase 3b–3i).
+///
+/// Registered under the temporary entry word `sqlinsert` so the
+/// SQL INSERT grammar and execution path can be exercised in
+/// isolation, WITHOUT yet making `insert` a shared DSL/SQL entry
+/// word. Sharing `insert` is sub-phase 3j, which depends on
+/// `shortid` auto-fill (3d) so advanced-mode DSL inserts keep
+/// parity rather than regressing through an incomplete SQL path.
+/// This scaffold (entry word + reconstruction in `build_sql_insert`)
+/// is removed when 3j wires the real `insert` entry word.
+pub static SQL_INSERT: CommandNode = CommandNode {
+    entry: Word::keyword("sqlinsert"),
+    shape: Node::Subgrammar(&sql_insert::SQL_INSERT_SHAPE),
+    ast_builder: build_sql_insert,
+    help_id: None,
+    usage_ids: &[],
+};
+
 // =================================================================
 // Tests — `explain` grammar (ADR-0028 §1)
 // =================================================================