Matrix: create table, DDL, and app-command coverage

55 tests covering create table, drop column, drop relationship
(endpoints + by-name), add relationship, rename/change column, and
all app-lifecycle commands. The drop-column and relationship tests
drove the §2.2 writes_table fix in the previous commit.

Documents one UX wrinkle as a flagged finding: partial entry words
(`qu`) classify as DefiniteErrorAt — same as unknown commands —
because the walker only engages on a complete entry word.

859 baseline -> 989 passing; 1 ignored (pre-existing doc-test).

tests/typing_surface/rename_change_column.rs

@@ -1 +1,99 @@
-//! Submodule stub — populated in subsequent tasks.
+//! Matrix coverage for `rename column [in] [table] <T> : <col>
+//! to <new>` and `change column [in] [table] <T> : <col>
+//! ( <type> ) [--force-conversion | --dont-convert]` (ADR-0013,
+//! ADR-0017).
+//!
+//! Both share the DDL `TABLE_NAME_EXISTING` slot, which now
+//! sets `writes_table` (handoff-13 §2.2) — so the column-name
+//! slot after the table narrows to that table's columns.
+
+use crate::typing_surface::*;
+use rdbms_playground::input_render::InputState;
+
+// ---- rename column ----
+
+#[test]
+fn rename_after_colon_narrows_to_active_table_columns() {
+    let schema = schema_multi_table();
+    let a = assess_at_end("rename column in Customers: ", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["id", "Name"]);
+    assert_no_candidate_named(&a, &["OrderId", "CustId", "Total"]);
+    crate::snap!("rename_after_colon_multi_table", a);
+}
+
+#[test]
+fn rename_after_old_column_expects_to() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end("rename column in Customers: Email ", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["to"]);
+    crate::snap!("rename_after_old_column", a);
+}
+
+#[test]
+fn rename_after_to_is_new_name_slot() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "rename column in Customers: Email to ",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    crate::snap!("rename_after_to", a);
+}
+
+#[test]
+fn complete_rename_column_parses() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "rename column in Customers: Email to ContactEmail",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::Valid));
+    assert_eq!(a.parse_result.as_deref(), Ok("RenameColumn"));
+    crate::snap!("complete_rename", a);
+}
+
+// ---- change column ----
+
+#[test]
+fn change_after_colon_narrows_to_active_table_columns() {
+    let schema = schema_multi_table();
+    let a = assess_at_end("change column in Customers: ", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["id", "Name"]);
+    assert_no_candidate_named(&a, &["OrderId", "CustId", "Total"]);
+    crate::snap!("change_after_colon_multi_table", a);
+}
+
+#[test]
+fn change_after_open_paren_offers_type_candidates() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end("change column in Customers: Email (", &schema);
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    assert_candidate_present(&a, &["text", "int", "bool", "decimal"]);
+    crate::snap!("change_after_open_paren", a);
+}
+
+#[test]
+fn complete_change_column_parses() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "change column in Customers: Email (text)",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::Valid));
+    assert_eq!(a.parse_result.as_deref(), Ok("ChangeColumnType"));
+    crate::snap!("complete_change", a);
+}
+
+#[test]
+fn change_column_with_force_conversion_flag_parses() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "change column in Customers: Email (int) --force-conversion",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::Valid));
+    crate::snap!("change_with_force", a);
+}