feat: V5 show tables / relationships / indexes list commands

Add the list-all show family as one Command::ShowList { kind }
variant. A read-only worker show_list formats count-headed lists
(reusing do_list_tables / read_all_relationships /
read_table_indexes, so it never drifts from the items panel);
internal __rdbms_* tables excluded. Help + parse-usage entries
added; 10 integration tests in tests/it/show_list.rs.

Mark V5 [x]. Split the singular show relationship/index <name>
detail forms (the [<name>] half) into a new tracked V5a [ ] item
rather than leaving them as an untracked footnote.

src/dsl/command.rs

@@ -332,6 +332,13 @@ pub enum Command {
     ShowTable {
         name: String,
     },
+    /// Re-display a whole schema collection — every table,
+    /// relationship, or index — as a list in the output (V5). The
+    /// read-only "all items" sibling of `ShowTable`; pure display,
+    /// no schema change.
+    ShowList {
+        kind: ShowListKind,
+    },
     /// Insert a single row. `columns` is `None` for the natural-
     /// order short form (`insert into T values (...)`); the
     /// executor fills in the column list by walking the schema.
@@ -746,6 +753,36 @@ pub enum IndexSelector {
     Columns { table: String, columns: Vec<String> },
 }
 
+/// Which schema collection a `show <kind>` list command displays (V5).
+///
+/// The bare plural forms list every item of the kind across the
+/// project; the singular `show table <name>` (a separate
+/// `Command::ShowTable`) shows one. The singular `show
+/// relationship <name>` / `show index <name>` forms are not yet
+/// provided — only the list-all forms land here.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ShowListKind {
+    /// `show tables` — every user table (internal `__rdbms_*`
+    /// tables excluded, as in the items panel).
+    Tables,
+    /// `show relationships` — every declared FK relationship.
+    Relationships,
+    /// `show indexes` — every index across all tables.
+    Indexes,
+}
+
+impl ShowListKind {
+    /// The full command name for the `name()` / echo surface.
+    #[must_use]
+    pub const fn command_name(self) -> &'static str {
+        match self {
+            Self::Tables => "show tables",
+            Self::Relationships => "show relationships",
+            Self::Indexes => "show indexes",
+        }
+    }
+}
+
 /// The action of an advanced-mode `ALTER TABLE` (ADR-0035 §4).
 ///
 /// Sub-phase 4e carries the column actions; 4f adds `AlterColumnType`;
@@ -860,6 +897,7 @@ impl Command {
             Self::AddConstraint { .. } => "add constraint",
             Self::DropConstraint { .. } => "drop constraint",
             Self::ShowTable { .. } => "show table",
+            Self::ShowList { kind } => kind.command_name(),
             Self::Insert { .. } => "insert into",
             Self::Update { .. } => "update",
             Self::Delete { .. } => "delete from",
@@ -948,6 +986,10 @@ impl Command {
             // result renders as a data view, not a structure
             // view, so an empty target is correct here.
             Self::Select { .. } => "",
+            // A `show <kind>` list spans every table (or none) —
+            // there is no single structure-target table; it renders
+            // as a list, not a structure view.
+            Self::ShowList { .. } => "",
             // A SQL `INSERT` carries its parsed target table (for
             // CSV re-persistence and ok-summary subject).
             Self::SqlInsert { target_table, .. }

src/dsl/grammar/data.rs

@@ -24,7 +24,7 @@
 //! later swap that capture for the same typed slots used here, adding
 //! live hints/highlighting.
 
-use crate::dsl::command::{Command, Expr, RowFilter};
+use crate::dsl::command::{Command, Expr, RowFilter, ShowListKind};
 use crate::dsl::grammar::{
     CommandNode, IdentSource, Node, NumberValidator, ValidationError, Word, expr,
     shared::{
@@ -99,7 +99,21 @@ const SHOW_TABLE_NODES: &[Node] = &[
 ];
 const SHOW_TABLE: Node = Node::Seq(SHOW_TABLE_NODES);
 
-const SHOW_CHOICES: &[Node] = &[SHOW_DATA, SHOW_TABLE];
+// `show tables` / `show relationships` / `show indexes` — the
+// list-all forms (V5). Each is a single keyword with no argument;
+// the executor lists every item of the kind. Distinct keyword
+// tokens (`tables` ≠ `table`), so Choice ordering is irrelevant.
+const SHOW_TABLES: Node = Node::Word(Word::keyword("tables"));
+const SHOW_RELATIONSHIPS: Node = Node::Word(Word::keyword("relationships"));
+const SHOW_INDEXES: Node = Node::Word(Word::keyword("indexes"));
+
+const SHOW_CHOICES: &[Node] = &[
+    SHOW_DATA,
+    SHOW_TABLE,
+    SHOW_TABLES,
+    SHOW_RELATIONSHIPS,
+    SHOW_INDEXES,
+];
 const SHOW_SHAPE: Node = Node::Choice(SHOW_CHOICES);
 
 // =================================================================
@@ -552,10 +566,23 @@ fn build_show(path: &MatchedPath, _source: &str) -> Result<Command, ValidationEr
             _ => None,
         })
         .nth(1);
-    let name = require_ident(path, "table_name")?;
     match sub {
         Some("data") => build_show_data(path, _source),
-        Some("table") => Ok(Command::ShowTable { name }),
+        // `name` is resolved only for the forms that carry one; the
+        // list-all forms (`tables` / `relationships` / `indexes`)
+        // have no table argument.
+        Some("table") => Ok(Command::ShowTable {
+            name: require_ident(path, "table_name")?,
+        }),
+        Some("tables") => Ok(Command::ShowList {
+            kind: ShowListKind::Tables,
+        }),
+        Some("relationships") => Ok(Command::ShowList {
+            kind: ShowListKind::Relationships,
+        }),
+        Some("indexes") => Ok(Command::ShowList {
+            kind: ShowListKind::Indexes,
+        }),
         _ => Err(ValidationError {
             message_key: "parse.error_wrapper",
             args: vec![("detail", "unknown show subcommand".to_string())],
@@ -1362,7 +1389,13 @@ pub static SHOW: CommandNode = CommandNode {
     shape: SHOW_SHAPE,
     ast_builder: build_show,
     help_id: Some("data.show"),
-    usage_ids: &["parse.usage.show_data", "parse.usage.show_table"],};
+    usage_ids: &[
+        "parse.usage.show_data",
+        "parse.usage.show_table",
+        "parse.usage.show_tables",
+        "parse.usage.show_relationships",
+        "parse.usage.show_indexes",
+    ],};
 
 pub static INSERT: CommandNode = CommandNode {
     entry: Word::keyword("insert"),

src/dsl/mod.rs

@@ -23,7 +23,7 @@ pub use action::ReferentialAction;
 pub use command::{
     AlterTableAction, AppCommand, ChangeColumnMode, ColumnSpec, Command, CompareOp, CopyScope, Expr,
     IndexSelector, MessagesValue, ModeValue, Operand, Predicate, RelationshipSelector, RowFilter,
-    SqlForeignKey,
+    ShowListKind, SqlForeignKey,
 };
 pub use parser::{ParseError, parse_command};
 pub use types::Type;