diff --git a/svelte/src/datum-editor.svelte b/svelte/src/datum-editor.svelte
index 7ac2c7d..72d39f6 100644
--- a/svelte/src/datum-editor.svelte
+++ b/svelte/src/datum-editor.svelte
@@ -1,3 +1,9 @@
+<!--
+@component
+Provides user interface for specifying arbitrary scalar `Datum` values, for
+example within the `<TableViewer />` or `<ExpressionEditor />`.
+-->
+
 <script lang="ts">
   import type { Datum } from "./datum.svelte";
   import {
@@ -5,19 +11,12 @@
     editor_state_from_datum,
     type EditorState,
   } from "./editor-state.svelte";
-  import { type FieldInfo } from "./field.svelte";
+  import { type Presentation } from "./presentation.svelte";
 
   const BLUR_DEBOUNCE_MS = 100;
 
   type Props = {
-    /**
-     * For use cases in which the user may select between multiple datum types,
-     * such as when embedded in an expression editor, this array represents the
-     * permissible set of field parameters.
-     */
-    assignable_fields?: ReadonlyArray<FieldInfo>;
-
-    field_info: FieldInfo;
+    current_presentation: Presentation;
 
     on_blur?(ev: FocusEvent): unknown;
 
@@ -36,25 +35,28 @@
      */
     on_restore_focus?(): unknown;
 
+    /**
+     * For use cases in which the user may select between multiple datum types,
+     * such as when embedded in an expression editor, this array represents the
+     * permissible set of available presentations.
+     */
+    potential_presentations?: Presentation[];
+
     value?: Datum;
   };
 
   let {
-    assignable_fields = [],
-    field_info = $bindable(),
+    current_presentation = $bindable(),
     on_blur,
     on_cancel_edit,
     on_change,
     on_focus,
     on_restore_focus,
+    potential_presentations = [],
     value = $bindable(),
   }: Props = $props();
 
   let editor_state = $state<EditorState | undefined>();
-  let type_selector_menu_button_element = $state<
-    HTMLButtonElement | undefined
-  >();
-  let type_selector_popover_element = $state<HTMLDivElement | undefined>();
   let date_input_element = $state<HTMLInputElement | undefined>();
   let text_input_element = $state<HTMLInputElement | undefined>();
   let blur_timeout = $state<number | undefined>();
@@ -67,13 +69,13 @@
 
   export function focus() {
     if (
-      field_info.field.presentation.t === "Dropdown" ||
-      field_info.field.presentation.t === "Numeric" ||
-      field_info.field.presentation.t === "Text" ||
-      field_info.field.presentation.t === "Uuid"
+      current_presentation.t === "Dropdown" ||
+      current_presentation.t === "Numeric" ||
+      current_presentation.t === "Text" ||
+      current_presentation.t === "Uuid"
     ) {
       text_input_element?.focus();
-    } else if (field_info.field.presentation.t === "Timestamp") {
+    } else if (current_presentation.t === "Timestamp") {
       date_input_element?.focus();
     }
   }
@@ -100,23 +102,10 @@
       console.warn("preconditions for handle_input() not met");
       return;
     }
-    value = datum_from_editor_state(
-      editor_state,
-      field_info.field.presentation,
-    );
+    value = datum_from_editor_state(editor_state, current_presentation);
     on_change?.(value);
   }
 
-  function handle_type_selector_menu_button_click() {
-    type_selector_popover_element?.togglePopover();
-  }
-
-  function handle_type_selector_field_button_click(value: FieldInfo) {
-    field_info = value;
-    type_selector_popover_element?.hidePopover();
-    type_selector_menu_button_element?.focus();
-  }
-
   function handle_keydown(ev: KeyboardEvent) {
     if (ev.key === "Enter") {
       on_restore_focus?.();
@@ -127,6 +116,9 @@
     }
   }
 
+  // These handlers must be passed to interactive children to correctly handle
+  // focus/blur behavior, particularly when the `<DatumEditor />` is a child of
+  // `<TableViewer />`.
   const interactive_handlers = {
     onblur: handle_blur,
     onfocus: handle_focus,
@@ -141,35 +133,19 @@
   onfocus={handle_focus}
 >
   {#if editor_state}
-    {#if assignable_fields?.length > 0}
+    {#if potential_presentations?.length > 0}
       <div class="datum-editor__type-selector">
-        <button
+        <select
           {...interactive_handlers}
-          bind:this={type_selector_menu_button_element}
-          class="datum-editor__type-selector-menu-button"
-          onclick={handle_type_selector_menu_button_click}
-          type="button"
+          oninput={(ev) => {
+            current_presentation =
+              potential_presentations[parseInt(ev.currentTarget.value)];
+          }}
         >
-          {field_info.field.presentation.t}
-        </button>
-        <div
-          bind:this={type_selector_popover_element}
-          class="datum-editor__type-selector-popover"
-          onblur={handle_blur}
-          onfocus={handle_focus}
-          popover="auto"
-        >
-          {#each assignable_fields as assignable_field_info}
-            <button
-              {...interactive_handlers}
-              onclick={() =>
-                handle_type_selector_field_button_click(assignable_field_info)}
-              type="button"
-            >
-              {assignable_field_info.field.presentation.t}
-            </button>
+          {#each potential_presentations as presentation, i}
+            <option value={`${i}`}>{presentation.t}</option>
           {/each}
-        </div>
+        </select>
       </div>
     {/if}
     <button
@@ -194,7 +170,7 @@
         <i class="ti ti-cube"></i>
       {/if}
     </button>
-    {#if ["Dropdown", "Numeric", "Text", "Uuid"].includes(field_info.field.presentation.t)}
+    {#if ["Dropdown", "Numeric", "Text", "Uuid"].includes(current_presentation.t)}
       <input
         {...interactive_handlers}
         bind:this={text_input_element}
@@ -213,7 +189,7 @@
         class="datum-editor__text-input"
         type="text"
       />
-    {:else if field_info.field.presentation.t === "Timestamp"}
+    {:else if current_presentation.t === "Timestamp"}
       <div class="datum-editor__timestamp-inputs">
         <input
           {...interactive_handlers}
@@ -248,10 +224,10 @@
       </div>
     {/if}
     <div class="datum-editor__helpers" tabindex="-1">
-      {#if field_info.field.presentation.t === "Dropdown"}
+      {#if current_presentation.t === "Dropdown"}
         <!-- TODO: This is an awkward way to implement a keyboard-navigable listbox. -->
         <menu class="datum-editor__dropdown-options">
-          {#each field_info.field.presentation.c.options as dropdown_option}
+          {#each current_presentation.c.options as dropdown_option}
             <!-- FIXME: validate or escape dropdown_option.color -->
             <li
               class={[
diff --git a/svelte/src/expression-editor.webc.svelte b/svelte/src/expression-editor.webc.svelte
index a62cac8..2a1ff78 100644
--- a/svelte/src/expression-editor.webc.svelte
+++ b/svelte/src/expression-editor.webc.svelte
@@ -14,29 +14,15 @@
   import ExpressionSelector from "./expression-selector.svelte";
   import { type PgExpressionAny } from "./expression.svelte";
   import ExpressionEditor from "./expression-editor.webc.svelte";
-  import { type FieldInfo } from "./field.svelte";
   import { RFC_3339_S, type Presentation } from "./presentation.svelte";
   import type { Datum } from "./datum.svelte";
 
-  const ASSIGNABLE_PRESENTATIONS: Presentation[] = [
+  const POTENTIAL_PRESENTATIONS: Presentation[] = [
+    { t: "Numeric", c: {} },
     { t: "Text", c: { input_mode: { t: "MultiLine", c: {} } } },
     { t: "Timestamp", c: { format: RFC_3339_S } },
     { t: "Uuid", c: {} },
   ];
-  const ASSIGNABLE_FIELDS: FieldInfo[] = ASSIGNABLE_PRESENTATIONS.map(
-    (presentation) => ({
-      field: {
-        id: "",
-        name: "",
-        ordinality: -1,
-        presentation,
-        table_label: "",
-        table_width_px: -1,
-      },
-      not_null: true,
-      has_default: false,
-    }),
-  );
 
   type Props = {
     identifier_hints?: string[];
@@ -47,7 +33,7 @@
 
   // Dynamic state to bind to datum editor.
   let editor_value = $state<Datum | undefined>();
-  let editor_field_info = $state<FieldInfo>(ASSIGNABLE_FIELDS[0]);
+  let editor_presentation = $state<Presentation>(POTENTIAL_PRESENTATIONS[0]);
 
   $effect(() => {
     editor_value = value?.t === "Literal" ? value.c : undefined;
@@ -93,9 +79,9 @@
           </select>
         {:else if value.t === "Literal"}
           <DatumEditor
-            bind:field_info={editor_field_info}
+            bind:current_presentation={editor_presentation}
             bind:value={editor_value}
-            assignable_fields={ASSIGNABLE_FIELDS}
+            potential_presentations={POTENTIAL_PRESENTATIONS}
             on_change={handle_editor_change}
           />
         {/if}
diff --git a/svelte/src/expression-selector.svelte b/svelte/src/expression-selector.svelte
index 4aad7bb..360041c 100644
--- a/svelte/src/expression-selector.svelte
+++ b/svelte/src/expression-selector.svelte
@@ -1,3 +1,9 @@
+<!--
+@component
+Dropdown menu with grid of buttons for quickly selecting a Postgres expression
+type. Used by `<ExpressionEditor />`.
+-->
+
 <script lang="ts">
   import { type PgExpressionAny, expression_icon } from "./expression.svelte";
 
diff --git a/svelte/src/table-viewer.webc.svelte b/svelte/src/table-viewer.webc.svelte
index 6181408..ad1b3b9 100644
--- a/svelte/src/table-viewer.webc.svelte
+++ b/svelte/src/table-viewer.webc.svelte
@@ -718,7 +718,8 @@
         <DatumEditor
           bind:this={datum_editor}
           bind:value={editor_value}
-          field_info={lazy_data.fields[selections[0].coords.field_idx]}
+          current_presentation={lazy_data.fields[selections[0].coords.field_idx]
+            .field.presentation}
           on_blur={() => try_queue_delta()}
           on_cancel_edit={cancel_edit}
           on_change={() => {