grammar+db: 3g — RETURNING on INSERT/UPDATE/DELETE (ADR-0033 §5)

Shared RETURNING_CLAUSE (reuses Phase-2 PROJECTION_LIST, now
pub(crate)) as an optional tail on all three SQL DML shapes.
`returning: bool` on the Command variants, set by the ast-builders
and threaded to the worker. run_returning collects the returned rows
as a DataResult (RETURNING mutates + yields in one pass), reusing
resolve_select_column_types for bare-column type recovery; computed
projections stay typeless. DeleteResult gains a `data` field rendered
alongside the cascade summary.

Follow-set fix: `returning` is added to the table-source and
projection bare-alias follow-sets so an INSERT … SELECT row source
stops before RETURNING instead of reading it as a table alias.

Auto-fill × RETURNING: build_sql_insert stops row_source before the
RETURNING token (keeping it preparable for shortid materialisation),
and plan_shortid_autofill re-appends the RETURNING tail so generated
shortids surface in RETURNING *.

Tests (+17): grammar accept on all three; INSERT/UPDATE/DELETE
RETURNING incl. *, aliases, multi-row, type recovery + computed-
typeless; auto-fill × RETURNING (single + multi-row distinct ids);
INSERT…SELECT…RETURNING execution; UPDATE…RETURNING zero-match;
DELETE…RETURNING cascade+rows; app-level render of both. Dev
sql_insert/sql_update/sql_delete entry words still removed in 3j.
1562 pass / 0 fail / 1 ignored. Clippy clean.

tests/sql_delete.rs

@@ -71,6 +71,7 @@ fn seed(db: &Database, rt: &tokio::runtime::Runtime, sql: &str, target: &str) {
         target.to_string(),
         Vec::new(),
         String::new(),
+        false,
     ))
     .unwrap_or_else(|e| panic!("seed {sql:?}: {e:?}"));
 }
@@ -82,8 +83,8 @@ fn run_delete(
     input: &str,
 ) -> Result<DeleteResult, DbError> {
     match parse_command(input).expect("parse sql_delete") {
-        Command::SqlDelete { sql, target_table } => {
-            rt.block_on(db.run_sql_delete(sql, Some(input.to_string()), target_table))
+        Command::SqlDelete { sql, target_table, returning } => {
+            rt.block_on(db.run_sql_delete(sql, Some(input.to_string()), target_table, returning))
         }
         other => panic!("expected Command::SqlDelete, got {other:?}"),
     }
@@ -117,7 +118,7 @@ fn parse_path_lowers_sql_delete_to_command() {
     let command = parse_command("sql_delete from Orders where id = 1")
         .expect("sql_delete parses in advanced mode");
     match command {
-        Command::SqlDelete { sql, target_table } => {
+        Command::SqlDelete { sql, target_table, .. } => {
             assert_eq!(sql, "delete from Orders where id = 1");
             assert_eq!(target_table, "Orders");
         }
@@ -424,3 +425,42 @@ fn internal_target_table_rejected_at_parse() {
         "internal table must be rejected at the DELETE target slot"
     );
 }
+
+// =================================================================
+// Sub-phase 3g — RETURNING (ADR-0033 §5)
+// =================================================================
+
+#[test]
+fn delete_returning_yields_predelete_row() {
+    let (project, db, _dir) = open_project_db();
+    let rt = rt();
+    create_cols(&db, &rt, "t", &[("id", Type::Int), ("v", Type::Text)], &["id"]);
+    seed(&db, &rt, "insert into t (id, v) values (1, 'gone'), (2, 'keep')", "t");
+    let result = run_delete(&db, &rt, "sql_delete from t where id = 1 returning *")
+        .expect("DELETE … RETURNING * runs");
+    assert_eq!(result.rows_affected, 1, "one row deleted");
+    // RETURNING yields the row as it was BEFORE deletion.
+    assert_eq!(result.data.rows.len(), 1, "the deleted row was returned");
+    assert_eq!(result.data.rows[0][1], Some("gone".to_string()));
+    // And it really is gone from the table.
+    let csv = read_csv(&project, "t").expect("t.csv");
+    assert!(!csv.contains("gone") && csv.contains("keep"), "row actually deleted: {csv:?}");
+}
+
+#[test]
+fn delete_returning_with_cascade_surfaces_both() {
+    // 3g: a parent DELETE … RETURNING must surface BOTH the returned
+    // (deleted) parent rows AND the per-relationship cascade summary.
+    let (_project, db, _dir) = open_project_db();
+    let rt = rt();
+    cascade_fixture(&db, &rt);
+    let result = run_delete(&db, &rt, "sql_delete from Customers where id = 1 returning *")
+        .expect("cascading DELETE … RETURNING runs");
+    assert_eq!(result.rows_affected, 1, "one parent row deleted");
+    // RETURNING gave the deleted customer row.
+    assert_eq!(result.data.rows.len(), 1, "deleted parent row returned");
+    // Cascade summary still computed alongside the result set.
+    assert_eq!(result.cascade.len(), 1, "cascade reported");
+    assert_eq!(result.cascade[0].child_table, "Orders");
+    assert_eq!(result.cascade[0].rows_changed, 2, "both Alice's orders cascaded");
+}