ADR-0024 Phase D: include column name in value-slot hint prose

User-facing improvement: typing into a value slot now surfaces
the column name in the hint. The hint at `insert into Customers
values (` (first column id:int) reads "for `id`: Type an
integer (e.g. 42, -7) or null" instead of the generic
"Type an integer …" prose. After `1, ` the panel updates to
the second column ("for `Name`: Type a quoted string …"). The
same applies to `update T set Email=` and `delete from T where
ts=` — the catalog wrapper threads the column name through.

Implementation:

**`Node::TypedValueSlot.column_name: Option<&'static str>`**
(new field, `src/dsl/grammar/mod.rs`). When `Some`, walker
writes `WalkContext::pending_value_column` on entry; clears
along with `pending_value_type` on inner success.

**Walker driver writes both names** (`src/dsl/walker/driver.rs`):
- `Node::TypedValueSlot` dispatch reads `column_name` and
  populates `pending_value_column`.
- `Ident { writes_column: true }` dispatch also writes
  `pending_value_column` (using the schema-canonical name when
  available, falling back to the user's spelling) so update
  set / where positions surface the column name.

**Shared sub-grammars** (`src/dsl/grammar/shared.rs`):
- New `slot_for_column(ty, name)` builds a `TypedValueSlot`
  with the embedded leaked column name. Used by
  `column_value_list`.
- New `slot_inner_for_type(ty)` returns just the Choice
  (without TypedValueSlot wrapper) for slot_for_column to
  rebuild.
- `column_value_list` factory now constructs per-column slots
  via `slot_for_column(col.user_type, &col.name)`. Each slot
  leaks its column name string with the same per-walk Box::leak
  pattern the rest of dynamic dispatch uses.

**`WalkContext::pending_value_column: Option<String>`** (new
field, `src/dsl/walker/context.rs`). Pairs with
`pending_value_type` to give the hint resolver both pieces.

**Single-walk hint resolver** (`src/dsl/walker/mod.rs`):
- New `HintResolution { mode: HintMode, column: Option<String> }`
  struct.
- New `hint_resolution_at_input(source, schema) -> Option<
  HintResolution>` runs one walk and reports both pieces. The
  ambient_hint dispatch composes per-column prose from the
  result.
- Existing `hint_mode_at_input` / `hint_mode_at_input_with_schema`
  preserved as thinner wrappers for tests / future callers
  that don't need the column name.

**Catalog wrapper** (`src/friendly/strings/en-US.yaml`,
`src/friendly/keys.rs`):
- New `hint.value_slot_for_column: "for `{column}`: {detail}"`
  prefixes the per-type prose with the actual column name when
  the walker has it bound. Schemaless fallback continues to use
  the generic value-literal prose with no column prefix.

**ambient_hint composes** (`src/input_render.rs`): consults
`hint_resolution_at_input`; when `column` is `Some`, wraps the
type prose through `hint.value_slot_for_column`; otherwise
emits the bare type prose.

Tests (846 total, 0 failing):
- 4 new input_render tests assert column names appear in the
  prose at insert/update/where positions plus the
  second-insert-value position (proves column tracking advances
  with comma).
- All existing tests pass unchanged — the column-name addition
  is layered on top of the type-only prose path.

Clippy clean.

src/dsl/grammar/mod.rs

@@ -287,12 +287,17 @@ pub enum Node {
     /// column type in `WalkContext::pending_value_type` so the
     /// hint resolver can emit per-type catalog prose ("Type an
     /// integer", "Type a date as 'YYYY-MM-DD'", …) at empty
-    /// prefix at this slot. The recorded type clears on a
+    /// prefix at this slot. When `column_name` is `Some`, the
-    /// successful inner match — so positions BETWEEN typed
+    /// walker also writes `pending_value_column` so the hint
-    /// slots (`insert into T values (1` mid-input) don't carry
+    /// can be rendered with the actual column name (e.g. "for
-    /// a stale hint type.
+    /// `Email`: Type a quoted string …") rather than a generic
+    /// type hint. The recorded values clear on a successful
+    /// inner match — so positions BETWEEN typed slots
+    /// (`insert into T values (1` mid-input) don't carry stale
+    /// hint state.
     TypedValueSlot {
         ty: crate::dsl::types::Type,
+        column_name: Option<&'static str>,
         inner: &'static Self,
     },
 }

src/dsl/grammar/shared.rs

@@ -189,10 +189,12 @@ const INT_SLOT_CHOICES: &[Node] = &[
 const INT_SLOT_INNER: Node = Node::Choice(INT_SLOT_CHOICES);
 const INT_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Int,
+    column_name: None,
     inner: &INT_SLOT_INNER,
 };
 const SERIAL_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Serial,
+    column_name: None,
     inner: &INT_SLOT_INNER,
 };
 
@@ -200,6 +202,7 @@ const REAL_SLOT_CHOICES: &[Node] = &[Node::NumberLit { validator: None }, NULL_W
 const REAL_SLOT_INNER: Node = Node::Choice(REAL_SLOT_CHOICES);
 const REAL_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Real,
+    column_name: None,
     inner: &REAL_SLOT_INNER,
 };
 
@@ -212,6 +215,7 @@ const DECIMAL_SLOT_CHOICES: &[Node] = &[
 const DECIMAL_SLOT_INNER: Node = Node::Choice(DECIMAL_SLOT_CHOICES);
 const DECIMAL_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Decimal,
+    column_name: None,
     inner: &DECIMAL_SLOT_INNER,
 };
 
@@ -223,6 +227,7 @@ const BOOL_SLOT_CHOICES: &[Node] = &[
 const BOOL_SLOT_INNER: Node = Node::Choice(BOOL_SLOT_CHOICES);
 const BOOL_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Bool,
+    column_name: None,
     inner: &BOOL_SLOT_INNER,
 };
 
@@ -230,6 +235,7 @@ const TEXT_SLOT_CHOICES: &[Node] = &[Node::StringLit, NULL_WORD];
 const TEXT_SLOT_INNER: Node = Node::Choice(TEXT_SLOT_CHOICES);
 const TEXT_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Text,
+    column_name: None,
     inner: &TEXT_SLOT_INNER,
 };
 
@@ -238,30 +244,36 @@ const TEXT_SLOT: Node = Node::TypedValueSlot {
 // the YYYY-MM-DD / YYYY-MM-DD HH:MM:SS format examples.
 const DATE_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Date,
+    column_name: None,
     inner: &TEXT_SLOT_INNER,
 };
 const DATETIME_SLOT: Node = Node::TypedValueSlot {
     ty: Type::DateTime,
+    column_name: None,
     inner: &TEXT_SLOT_INNER,
 };
 const BLOB_SLOT: Node = Node::TypedValueSlot {
     ty: Type::Blob,
+    column_name: None,
     inner: &TEXT_SLOT_INNER,
 };
 // shortid columns store base58 text (ADR-0011 fk_target_type
 // shortid → text); the slot accepts a quoted-text literal or
-// null. The pre-Phase-D plain-Choice scaffolding had this
+// null.
-// mapped to INT_SLOT (a holdover from the chumsky-side generic
-// VALUE_LITERAL fallback). Per-type dispatch corrects that.
 const SHORTID_SLOT: Node = Node::TypedValueSlot {
     ty: Type::ShortId,
+    column_name: None,
     inner: &TEXT_SLOT_INNER,
 };
 
 /// Dispatch a value slot per user-facing type
-/// (ADR-0024 §slot_for_type). Returns the same node every time
+/// (ADR-0024 §slot_for_type).
-/// for a given Type — fine to call from within a
+///
-/// `DynamicSubgrammar` factory.
+/// Returns the same node every time for a given Type — fine to
+/// call from within a `DynamicSubgrammar` factory. The
+/// returned slot does not carry a column name; callers that
+/// have one (e.g. `column_value_list` building per-column
+/// slots) should use [`slot_for_column`] instead.
 #[must_use]
 pub const fn slot_for_type(ty: Type) -> Node {
     match ty {
@@ -278,6 +290,45 @@ pub const fn slot_for_type(ty: Type) -> Node {
     }
 }
 
+/// Look up just the inner Choice (no `TypedValueSlot` wrapper)
+/// for a given user-facing type. Used by `slot_for_column` to
+/// rebuild a TypedValueSlot with an embedded column name.
+const fn slot_inner_for_type(ty: Type) -> &'static Node {
+    match ty {
+        Type::Int | Type::Serial => &INT_SLOT_INNER,
+        Type::Real => &REAL_SLOT_INNER,
+        Type::Decimal => &DECIMAL_SLOT_INNER,
+        Type::Bool => &BOOL_SLOT_INNER,
+        Type::Text | Type::Date | Type::DateTime | Type::Blob | Type::ShortId => {
+            &TEXT_SLOT_INNER
+        }
+    }
+}
+
+/// Build a typed value slot with an embedded column name
+/// (ADR-0024 §Phase D §typed-value-slots). Used by
+/// `column_value_list` to attach each column's name so the
+/// hint resolver can render "for `<column>`:" prefixes.
+///
+/// The walker writes the (leaked) name into
+/// `WalkContext::pending_value_column` on entry to the slot
+/// and clears it on successful inner match.
+#[must_use]
+fn slot_for_column(ty: Type, name: &str) -> Node {
+    // `Box::leak`: column names from the schema cache need a
+    // `&'static str`-compatible lifetime to plug into the
+    // static Node enum. The leak is per dynamic walk (factory
+    // invocation), bounded by the column count — consistent
+    // with the `DynamicSubgrammar` Box::leak in the walker
+    // driver.
+    let leaked: &'static str = Box::leak(name.to_string().into_boxed_str());
+    Node::TypedValueSlot {
+        ty,
+        column_name: Some(leaked),
+        inner: slot_inner_for_type(ty),
+    }
+}
+
 // =================================================================
 // Dynamic sub-grammar: column_value_list
 // =================================================================
@@ -329,12 +380,15 @@ pub fn column_value_list(ctx: &WalkContext) -> Node {
         return FALLBACK_VALUE_LIST;
     }
     // Build a Seq of typed slots interleaved with commas.
+    // Each slot embeds its column name so the hint resolver
+    // can mention the column by name ("for `Email`: Type a
+    // quoted string …").
     let mut children: Vec<Node> = Vec::with_capacity(cols.len() * 2);
     for (i, col) in cols.iter().enumerate() {
         if i > 0 {
             children.push(Node::Punct(','));
         }
-        children.push(slot_for_type(col.user_type));
+        children.push(slot_for_column(col.user_type, &col.name));
     }
     Node::Seq(Box::leak(children.into_boxed_slice()))
 }

src/dsl/walker/context.rs

@@ -38,6 +38,22 @@ pub struct WalkContext<'a> {
     /// emit per-type prose ("Type an integer", "Type a date as
     /// 'YYYY-MM-DD'", …) at empty prefix at typed value slots.
     pub pending_value_type: Option<crate::dsl::types::Type>,
+    /// The column name (if known) the walker is about to
+    /// consume a value for.
+    ///
+    /// Populated by:
+    /// - `Ident { source: Columns, writes_column: true }` for
+    ///   `update set <col>=` and `where <col>=` positions, where
+    ///   the column ident matches in the path immediately
+    ///   before the value slot.
+    /// - `Node::TypedValueSlot { column_name: Some(name), … }`
+    ///   for the per-column typed slots in `column_value_list`
+    ///   (insert-into-T-values positions, where the column name
+    ///   is keyed by position in the table's column list).
+    ///
+    /// Cleared on successful inner match alongside
+    /// `pending_value_type`.
+    pub pending_value_column: Option<String>,
 }
 
 impl<'a> WalkContext<'a> {
@@ -60,6 +76,7 @@ impl<'a> WalkContext<'a> {
             current_table_columns: None,
             current_column: None,
             pending_value_type: None,
+            pending_value_column: None,
         }
     }
 }

src/dsl/walker/driver.rs

@@ -130,17 +130,27 @@ pub fn walk_node(
             let resolved: &'static Node = Box::leak(Box::new(factory(ctx)));
             walk_node(source, pos, resolved, ctx, path, per_byte)
         }
-        Node::TypedValueSlot { ty, inner } => {
+        Node::TypedValueSlot {
+            ty,
+            column_name,
+            inner,
+        } => {
             // ADR-0024 §Phase D §typed-value-slots. Tag the
             // pending column type so the hint resolver can emit
-            // per-type prose at empty prefix. Clear on
+            // per-type prose at empty prefix. If a column name
-            // successful inner match — positions BETWEEN typed
+            // is embedded (insert column_value_list path), tag
-            // slots (post-comma, between values) don't carry a
+            // that too so the hint can mention the column by
-            // stale hint type.
+            // name. Clear on successful inner match — positions
+            // BETWEEN typed slots (post-comma, between values)
+            // don't carry stale hint state.
             ctx.pending_value_type = Some(*ty);
+            if let Some(name) = column_name {
+                ctx.pending_value_column = Some((*name).to_string());
+            }
             let result = walk_node(source, pos, inner, ctx, path, per_byte);
             if matches!(result, NodeWalkResult::Matched { .. }) {
                 ctx.pending_value_type = None;
+                ctx.pending_value_column = None;
             }
             result
         }
@@ -268,6 +278,16 @@ fn walk_ident(
                 .find(|c| c.name.eq_ignore_ascii_case(&text))
                 .cloned()
         });
+        // Surface the column name to the hint resolver too —
+        // this is the `update <T> set <col>=` / `where <col>=`
+        // path. The matching column's canonical name (from the
+        // schema) wins over the user's spelling so the hint
+        // mirrors what's in the schema.
+        ctx.pending_value_column = ctx
+            .current_column
+            .as_ref()
+            .map(|c| c.name.clone())
+            .or_else(|| Some(text.clone()));
     }
     path.push(MatchedItem {
         kind: MatchedKind::Ident { role },

src/dsl/walker/mod.rs

@@ -64,6 +64,80 @@ pub fn hint_mode_at_input_with_schema(
     hint_mode_at_input_inner(source, Some(schema))
 }
 
+/// Resolution of the hint-panel mode at the cursor, plus the
+/// column name (if known) the cursor's value slot is keyed on.
+///
+/// Returned by [`hint_resolution_at_input`]. The renderer
+/// composes per-column prose ("for `Email`: Type a quoted
+/// string …") when `column` is `Some`.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct HintResolution {
+    pub mode: crate::dsl::grammar::HintMode,
+    pub column: Option<String>,
+}
+
+/// Single-walk hint resolver (ADR-0024 §Phase D §typed-value-slots).
+///
+/// Walks `source` against `schema`, then reports both the
+/// resolved `HintMode` and the walker's `pending_value_column`
+/// (if any). Returns `None` when no HintMode applies.
+#[must_use]
+pub fn hint_resolution_at_input(
+    source: &str,
+    schema: Option<&crate::completion::SchemaCache>,
+) -> Option<HintResolution> {
+    use crate::dsl::grammar::{HintMode, IdentSource};
+    use crate::dsl::walker::outcome::Expectation;
+
+    let (expected, pending_type, pending_column) =
+        expected_for_hint_with_full_ctx(source, schema);
+    if expected.is_empty() {
+        return None;
+    }
+
+    if let Some(ty) = pending_type {
+        return Some(HintResolution {
+            mode: HintMode::ProseOnly(catalog_key_for_value_type(ty)),
+            column: pending_column,
+        });
+    }
+
+    let has_word = |w: &str| {
+        expected
+            .iter()
+            .any(|e| matches!(e, Expectation::Word(x) if *x == w))
+    };
+    let value_literal_slot = has_word("null")
+        && has_word("true")
+        && has_word("false")
+        && expected.iter().any(|e| matches!(e, Expectation::NumberLit))
+        && expected.iter().any(|e| matches!(e, Expectation::StringLit));
+    if value_literal_slot {
+        return Some(HintResolution {
+            mode: HintMode::ProseOnly("hint.value_literal_slot"),
+            column: None,
+        });
+    }
+
+    let new_name_slot = expected.iter().any(|e| {
+        matches!(
+            e,
+            Expectation::Ident {
+                source: IdentSource::NewName,
+                ..
+            }
+        )
+    });
+    if new_name_slot {
+        return Some(HintResolution {
+            mode: HintMode::ForceProse("hint.ambient_typing_name"),
+            column: None,
+        });
+    }
+
+    None
+}
+
 fn hint_mode_at_input_inner(
     source: &str,
     schema: Option<&crate::completion::SchemaCache>,
@@ -209,6 +283,18 @@ fn expected_for_hint_with_ctx(
     source: &str,
     schema: Option<&crate::completion::SchemaCache>,
 ) -> (Vec<outcome::Expectation>, Option<crate::dsl::types::Type>) {
+    let (expected, ty, _col) = expected_for_hint_with_full_ctx(source, schema);
+    (expected, ty)
+}
+
+fn expected_for_hint_with_full_ctx(
+    source: &str,
+    schema: Option<&crate::completion::SchemaCache>,
+) -> (
+    Vec<outcome::Expectation>,
+    Option<crate::dsl::types::Type>,
+    Option<String>,
+) {
     use crate::dsl::grammar::REGISTRY;
 
     if source.trim().is_empty() {
@@ -216,7 +302,7 @@ fn expected_for_hint_with_ctx(
             .iter()
             .map(|c| outcome::Expectation::Word(c.entry.primary))
             .collect();
-        return (expected, None);
+        return (expected, None, None);
     }
     let mut ctx = schema.map_or_else(context::WalkContext::new, |s| {
         context::WalkContext::with_schema(s)
@@ -227,7 +313,7 @@ fn expected_for_hint_with_ctx(
             .iter()
             .map(|c| outcome::Expectation::Word(c.entry.primary))
             .collect();
-        return (expected, None);
+        return (expected, None, None);
     };
     let expected = match result.outcome {
         outcome::WalkOutcome::Match { .. } | outcome::WalkOutcome::ValidationFailed { .. } => {
@@ -236,7 +322,7 @@ fn expected_for_hint_with_ctx(
         outcome::WalkOutcome::Incomplete { expected, .. }
         | outcome::WalkOutcome::Mismatch { expected, .. } => expected,
     };
-    (expected, ctx.pending_value_type)
+    (expected, ctx.pending_value_type, ctx.pending_value_column)
 }
 
 /// Public walk entry. `bound` is `EndOfInput` for parse;

src/friendly/keys.rs

@@ -149,6 +149,7 @@ pub const KEYS_AND_PLACEHOLDERS: &[(&str, &[&str])] = &[
     ("hint.value_slot_serial", &[]),
     ("hint.value_slot_shortid", &[]),
     ("hint.value_slot_text", &[]),
+    ("hint.value_slot_for_column", &["column", "detail"]),
     // ---- Parse error rendering ----
     ("parse.available_commands", &["commands"]),
     ("parse.caret", &["padding"]),

src/friendly/strings/en-US.yaml

@@ -303,6 +303,10 @@ hint:
   value_slot_blob: "Type a quoted blob literal or null"
   value_slot_serial: "Type an integer (or omit to auto-generate) or null"
   value_slot_shortid: "Type a quoted shortid (or omit to auto-generate) or null"
+  # Wrapper that prefixes a per-column-type slot hint with the
+  # actual column name so the user sees "for `Email`: Type a
+  # quoted string …" instead of the generic type prose.
+  value_slot_for_column: "for `{column}`: {detail}"
 
 parse:
   # Wrapper around chumsky's structural error message. The

src/input_render.rs

@@ -191,9 +191,11 @@ pub fn ambient_hint(
     let leading = hint_leading_slice(input, cursor);
     // ADR-0024 §Phase D §typed-value-slots: pass the schema so
     // the resolver can narrow value-slot prose per column type
-    // (Date → "Type a date as 'YYYY-MM-DD'", etc.).
+    // (Date → "Type a date as 'YYYY-MM-DD'", etc.) and surface
-    let hint_mode = crate::dsl::walker::hint_mode_at_input_with_schema(leading, cache);
+    // the column name when the walker has it bound.
-    match hint_mode {
+    let resolution =
+        crate::dsl::walker::hint_resolution_at_input(leading, Some(cache));
+    match resolution.as_ref().map(|r| r.mode) {
         Some(crate::dsl::grammar::HintMode::ProseOnly(key)) => {
             // The cursor sits at a slot where Tab candidates
             // would be actively misleading. Surface the catalog
@@ -201,7 +203,16 @@ pub fn ambient_hint(
             // once the user starts typing a partial, normal
             // candidate completion (e.g. `n` → `null`) applies.
             if cursor_partial_is_empty(input, cursor) {
-                return Some(AmbientHint::Prose(crate::friendly::translate(key, &[])));
+                let detail = crate::friendly::translate(key, &[]);
+                let composed = match resolution.and_then(|r| r.column) {
+                    Some(column) => crate::t!(
+                        "hint.value_slot_for_column",
+                        column = column,
+                        detail = detail
+                    ),
+                    None => detail,
+                };
+                return Some(AmbientHint::Prose(composed));
             }
         }
         Some(crate::dsl::grammar::HintMode::ForceProse(_key)) => {
@@ -662,6 +673,89 @@ mod tests {
         }
     }
 
+    #[test]
+    fn ambient_hint_at_insert_first_value_mentions_column_name() {
+        use crate::dsl::types::Type;
+        let cache = schema_with_columns(
+            "Customers",
+            &[("id", Type::Int), ("Name", Type::Text)],
+        );
+        let input = "insert into Customers values (";
+        match ambient_hint(input, input.len(), None, &cache) {
+            Some(AmbientHint::Prose(p)) => {
+                assert!(p.contains("id"), "expected column name `id`, got {p:?}");
+                assert!(
+                    p.contains("integer"),
+                    "expected int prose, got {p:?}",
+                );
+            }
+            other => panic!("expected Prose, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn ambient_hint_at_update_set_mentions_column_name() {
+        use crate::dsl::types::Type;
+        let cache = schema_with_columns(
+            "Customers",
+            &[("id", Type::Int), ("Email", Type::Text)],
+        );
+        let input = "update Customers set Email=";
+        match ambient_hint(input, input.len(), None, &cache) {
+            Some(AmbientHint::Prose(p)) => {
+                assert!(
+                    p.contains("Email"),
+                    "expected column name `Email`, got {p:?}",
+                );
+                assert!(
+                    p.contains("quoted string"),
+                    "expected text prose, got {p:?}",
+                );
+            }
+            other => panic!("expected Prose, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn ambient_hint_at_where_mentions_column_name() {
+        use crate::dsl::types::Type;
+        let cache = schema_with_columns("Events", &[("ts", Type::DateTime)]);
+        let input = "delete from Events where ts=";
+        match ambient_hint(input, input.len(), None, &cache) {
+            Some(AmbientHint::Prose(p)) => {
+                assert!(p.contains("ts"), "expected column name `ts`, got {p:?}");
+                assert!(
+                    p.contains("YYYY-MM-DD"),
+                    "expected datetime prose, got {p:?}",
+                );
+            }
+            other => panic!("expected Prose, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn ambient_hint_at_second_insert_value_mentions_second_column() {
+        use crate::dsl::types::Type;
+        let cache = schema_with_columns(
+            "Customers",
+            &[("id", Type::Int), ("Name", Type::Text)],
+        );
+        let input = "insert into Customers values (1, ";
+        match ambient_hint(input, input.len(), None, &cache) {
+            Some(AmbientHint::Prose(p)) => {
+                assert!(
+                    p.contains("Name"),
+                    "expected second column `Name`, got {p:?}",
+                );
+                assert!(
+                    p.contains("quoted string"),
+                    "expected text prose, got {p:?}",
+                );
+            }
+            other => panic!("expected Prose, got {other:?}"),
+        }
+    }
+
     #[test]
     fn ambient_hint_at_value_slot_falls_back_to_generic_without_schema() {
         // Empty cache: the walker can't resolve the column type