Matrix: insert Form C + update + delete coverage

34 new tests covering:
- Form C bare-value-list (happy path + Form-A-recovery + type-unaware grammar limitation per handoff §2.2)
- update with WHERE (column-narrowing invariant per handoff §1 bug E1; typed-slot prose for assignments and where filters)
- update --all-rows (filter-clause requirement per ADR-0014)
- delete with WHERE (column-narrowing; typed-slot prose for where filters)
- delete --all-rows

859 baseline -> 931 passing. No bugs surfaced — the data-mutation
command family was already well-shaped post-Phase-D.

tests/typing_surface/update_with_where.rs

@@ -1 +1,169 @@
-//! Submodule stub — populated in subsequent tasks.
+//! Matrix coverage for `update T set col=val where col=val`.
+//!
+//! Per ADR-0014, update requires either WHERE or `--all-rows`.
+//! Handoff §1 bug E1 (`update T set ` showing every table's
+//! columns) was fixed in commit 619a8bd via
+//! `completion_probe`; these tests pin the per-table narrowing
+//! invariant.
+
+use crate::typing_surface::*;
+use rdbms_playground::input_render::InputState;
+
+#[test]
+fn after_update_keyword_expects_table_name() {
+    let schema = schema_multi_table();
+    let a = assess_at_end("update ", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["Customers", "Orders"]);
+    crate::snap!("after_update", a);
+}
+
+#[test]
+fn after_table_name_expects_set_keyword() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end("update Customers ", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["set"]);
+    crate::snap!("after_table_name", a);
+}
+
+// =========================================================
+// Handoff §1 bug E1 — `update T set ` must narrow column
+// candidates to the active table.
+// =========================================================
+
+#[test]
+fn after_set_offers_only_active_table_columns_no_leakage() {
+    let schema = schema_multi_table();
+    let a = assess_at_end("update Customers set ", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    // Customers's columns must be offered.
+    assert_candidate_present(&a, &["id", "Name"]);
+    // Orders's columns must NOT leak.
+    assert_no_candidate_named(&a, &["OrderId", "CustId", "Total"]);
+    crate::snap!("after_set_multi_table", a);
+}
+
+#[test]
+fn after_set_serial_pk_offers_all_columns() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end("update Customers set ", &schema);
+    assert_candidate_present(&a, &["id", "Name", "Email"]);
+    crate::snap!("after_set_serial_pk", a);
+}
+
+#[test]
+fn after_set_column_expects_equals() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end("update Customers set Email", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    crate::snap!("after_set_column", a);
+}
+
+#[test]
+fn after_equals_offers_typed_slot_prose_for_column() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end("update Customers set Email=", &schema);
+    let prose = hint_prose(&a).unwrap_or_else(|| {
+        panic!("expected Prose, got {:?}", a.hint)
+    });
+    assert!(
+        prose.contains("Email"),
+        "should name `Email`, got prose: {prose:?}",
+    );
+    assert!(
+        prose.contains("quoted string"),
+        "should say `quoted string` (text type), got prose: {prose:?}",
+    );
+    crate::snap!("after_equals_text_col", a);
+}
+
+#[test]
+fn after_equals_for_date_column_says_yyyy_mm_dd() {
+    let schema = schema_every_type();
+    let a = assess_at_end("update Things set dt=", &schema);
+    let prose = hint_prose(&a).unwrap_or_else(|| {
+        panic!("expected Prose, got {:?}", a.hint)
+    });
+    assert!(
+        prose.contains("YYYY-MM-DD"),
+        "date-slot prose should reference YYYY-MM-DD, got {prose:?}",
+    );
+    crate::snap!("after_equals_date_col", a);
+}
+
+#[test]
+fn mid_assignment_list_after_comma_offers_remaining_columns() {
+    let schema = schema_multi_table();
+    let a = assess_at_end(
+        "update Customers set Name='x', ",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    // Customers columns offered, no leakage.
+    assert_candidate_present(&a, &["id"]);
+    assert_no_candidate_named(&a, &["OrderId", "CustId", "Total"]);
+    crate::snap!("mid_assignment_list", a);
+}
+
+#[test]
+fn after_assignments_expects_where_or_all_rows() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "update Customers set Email='new@b.c' ",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["where", "--all-rows"]);
+    crate::snap!("after_assignments", a);
+}
+
+// =========================================================
+// WHERE clause column position — also schema-narrowed.
+// =========================================================
+
+#[test]
+fn after_where_keyword_offers_active_table_columns() {
+    let schema = schema_multi_table();
+    let a = assess_at_end(
+        "update Customers set Name='x' where ",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["id", "Name"]);
+    assert_no_candidate_named(&a, &["OrderId", "CustId", "Total"]);
+    crate::snap!("after_where", a);
+}
+
+#[test]
+fn after_where_column_equals_offers_typed_prose() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "update Customers set Email='x' where id=",
+        &schema,
+    );
+    let prose = hint_prose(&a).unwrap_or_else(|| {
+        panic!("expected Prose, got {:?}", a.hint)
+    });
+    assert!(
+        prose.contains("id"),
+        "should name where column `id`, got prose: {prose:?}",
+    );
+    crate::snap!("after_where_equals", a);
+}
+
+// =========================================================
+// Complete update parses to Update.
+// =========================================================
+
+#[test]
+fn complete_update_with_where_parses() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "update Customers set Email='new@b.c' where id=1",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::Valid));
+    assert_eq!(a.parse_result.as_deref(), Ok("Update"));
+    crate::snap!("complete_update", a);
+}