diff --git a/.changeset/palette-a11y-names.md b/.changeset/palette-a11y-names.md
new file mode 100644
index 0000000..5e8e0e7
--- /dev/null
+++ b/.changeset/palette-a11y-names.md
@@ -0,0 +1,5 @@
+---
+"acture-palette-react": patch
+---
+
+Accessibility: the picker chain's text step now has an accessible name (the parameter name), and its validation error is announced (`role="alert"`, `aria-describedby`, `aria-invalid`). Adds `palette.a11y.test.tsx`, which pins the APG combobox roles, `aria-activedescendant` and the focus hand-off between the list, the picker chain and a host form.
diff --git a/.claude/skills/acture-palette-design/SKILL.md b/.claude/skills/acture-palette-design/SKILL.md
index 7306372..05a0445 100644
--- a/.claude/skills/acture-palette-design/SKILL.md
+++ b/.claude/skills/acture-palette-design/SKILL.md
@@ -97,6 +97,30 @@ Peer range is `@rjsf` `^5.20.0 || ^6.0.0`, and CI installs and tests both majors
 
 Acture's core does not bundle a form library. Per redesign-takeaways §2.3.
 
+## Unavailable commands: hidden or disabled? (decided, research-12 §3.2)
+
+A command whose `when` is false is **unavailable**. What a surface does with it is a per-surface rule, not a property of the record:
+
+| Surface | Unavailable command is… | Why |
+| --- | --- | --- |
+| Command palette (`acture-palette-react`) | **hidden**, when the host passes `context` (`registry.list({ context })` drops it; without `context`, `when` is not evaluated and an unavailable command fails at dispatch) | The palette is a search box; unavailable rows are noise and VS Code does the same. |
+| AI tool list / MCP | **should be hidden; not implemented yet.** `acture-mcp-server` and `acture-ai-vercel` call `registry.list()` without a context, so they list every command and an unavailable one fails with `when_clause_failed` at dispatch | A tool the model cannot usefully call only invites a failed call. |
+| Menu, toolbar, button, native menu | **shown, disabled** | These are spatial and persistent; a vanishing item breaks muscle memory and hides what the app can do. |
+
+For the "shown, disabled" surfaces, build the projection from the **unfiltered** `registry.list()` and evaluate `when` yourself with `evaluateWhen(cmd.when, ctx)`. Map the result to `aria-disabled="true"` (not the `disabled` attribute, which takes the control out of the tab order, so keyboard users can no longer reach it and learn why it is off; APG menu items stay focusable), `AXEnabled: false` (macOS), `IsEnabled: false` (UIA), or Electron/Tauri `enabled: false`. A disabled command must not advertise a live shortcut (`aria-keyshortcuts`).
+
+A palette host that wants the menu convention instead can render its own rows from the unfiltered list and pass the `disabled` prop to `Command.Item` (cmdk renders `aria-disabled` itself, overwriting any `aria-disabled` you pass, and skips disabled items in keyboard navigation). That is a host choice; the shipped palette keeps hiding.
+
+## Accessibility contract (tested in `palette.a11y.test.tsx`)
+
+`acture-palette-react` inherits the WAI-ARIA APG combobox pattern from cmdk and pins it with tests. Keep these true when changing the palette:
+
+- The input is `role="combobox"` with `aria-controls` pointing at the `listbox`, named by the `label` ("Command palette"); rows are `option`s inside named `group`s.
+- DOM focus stays in the input; the highlighted row is `aria-selected` and `aria-activedescendant` follows it. (cmdk 1.1.1 only publishes `aria-activedescendant` once the highlight moves; the very first row is not announced until the first arrow key.)
+- When the view switches, the new view's first input takes focus (`autoFocus`), and cancelling returns to the list with the input focused. A host `formAdapter` owns focus inside its form and must `autoFocus` its first field.
+- Every text input the palette renders has an accessible name (the parameter name), and a validation error is `role="alert"`, linked by `aria-describedby`, with `aria-invalid` on the input.
+- Decorative icons are `aria-hidden`; the visible title is part of the option's text (WCAG 2.5.3).
+
 ## The don't-do list (research-2 §9.5)
 
 1. **Do not parse a single text blob into multiple parameters.** Slack's pattern. H2 hate; industry is migrating away.
@@ -122,3 +146,4 @@ The original wrapex `paletteHint` for delegating to a UI panel (Pattern D in `pa
 - `docs/parameterized_command_palette_guide.md` — implementation patterns (defer to research-2 on UX conflicts)
 - `acture-command-record-shape` — the `kind` field spec
 - `acture-schema-bridge` — how `params` projects to forms
+- `docs/research/acture_research_12 -- Accessibility APIs and Command Dispatch.md` — the accessibility alignment this section comes from
diff --git a/packages/palette-react/src/palette.a11y.test.tsx b/packages/palette-react/src/palette.a11y.test.tsx
new file mode 100644
index 0000000..f4262fb
--- /dev/null
+++ b/packages/palette-react/src/palette.a11y.test.tsx
@@ -0,0 +1,243 @@
+/// <reference lib="dom" />
+/**
+ * Accessibility contract of `<CommandPalette />` (research-12 §3 item 5, #64).
+ *
+ * The palette inherits the WAI-ARIA APG combobox pattern from cmdk. These
+ * tests pin that inheritance down — roles, the accessible name, the
+ * `aria-activedescendant` roving highlight — and the focus hand-off when the
+ * view switches (list → picker chain / form → back to the list), so a cmdk
+ * upgrade or an acture refactor cannot silently drop it.
+ */
+import { describe, it, expect, afterEach } from 'vitest';
+import { render, screen, fireEvent, cleanup, act } from '@testing-library/react';
+import { z } from 'zod';
+import { createRegistry, defineCommand, ok } from 'acture';
+import { CommandPalette } from './palette.js';
+import type { PaletteFormAdapter } from './palette.js';
+
+afterEach(() => cleanup());
+
+function setup() {
+  const registry = createRegistry();
+  registry.registerAll([
+    defineCommand({
+      id: 'app.view.zoomToFit',
+      title: 'Zoom to fit',
+      category: 'View',
+      execute: () => ok('zoomed'),
+    }),
+    defineCommand({
+      id: 'app.selection.selectAll',
+      title: 'Select all',
+      category: 'Selection',
+      execute: () => ok('selected'),
+    }),
+    defineCommand({
+      id: 'app.style.set',
+      title: 'Set style',
+      category: 'Style',
+      params: z.object({ variant: z.enum(['solid', 'dashed']) }),
+      execute: (p) => ok(p),
+    }),
+    defineCommand({
+      id: 'app.graph.addNode',
+      title: 'Add node',
+      category: 'Graph',
+      params: z.object({ label: z.string(), size: z.number() }),
+      execute: (p) => ok(p),
+    }),
+  ]);
+  return registry;
+}
+
+describe('<CommandPalette /> accessibility', () => {
+  it('exposes the APG combobox pattern: combobox input controlling a listbox of options', () => {
+    render(<CommandPalette registry={setup()} />);
+    const input = screen.getByRole('combobox');
+    const listbox = screen.getByRole('listbox');
+    expect(input.getAttribute('aria-autocomplete')).toBe('list');
+    expect(input.getAttribute('aria-expanded')).toBe('true');
+    expect(input.getAttribute('aria-controls')).toBe(listbox.id);
+    expect(screen.getAllByRole('option')).toHaveLength(4);
+  });
+
+  it('gives the palette, the listbox and the input an accessible name', () => {
+    const { container } = render(<CommandPalette registry={setup()} />);
+    const root = container.querySelector('[cmdk-root]')!;
+    expect(root.getAttribute('data-acture-palette-view')).toBe('list');
+    // `label` on <Command> is rendered as a visually-hidden <label> naming the input.
+    const input = screen.getByRole('combobox');
+    const labelId = input.getAttribute('aria-labelledby');
+    expect(labelId).toBeTruthy();
+    expect(document.getElementById(labelId!)?.textContent).toBe('Command palette');
+    expect(screen.getByRole('listbox').getAttribute('aria-label')).toBeTruthy();
+  });
+
+  it('groups options under named groups', () => {
+    render(<CommandPalette registry={setup()} />);
+    const groups = screen.getAllByRole('group');
+    const names = groups.map((g) => g.getAttribute('aria-labelledby'))
+      .map((id) => (id ? document.getElementById(id)?.textContent : null));
+    expect(names).toEqual(expect.arrayContaining(['View', 'Selection', 'Style', 'Graph']));
+  });
+
+  it('keeps DOM focus in the input and moves aria-activedescendant with the arrow keys', async () => {
+    render(<CommandPalette registry={setup()} />);
+    // cmdk publishes the highlighted option id one scheduled flush after mount.
+    await act(async () => {});
+    const input = screen.getByRole('combobox');
+    expect(document.activeElement).toBe(input);
+
+    const selectedOptionId = (): string | null =>
+      screen.getAllByRole('option').find((o) => o.getAttribute('aria-selected') === 'true')?.id ?? null;
+
+    // Exactly one option is highlighted from the start.
+    const first = selectedOptionId();
+    expect(first).toBeTruthy();
+    // Known cmdk 1.1.1 quirk: `aria-activedescendant` is only published once the
+    // highlight MOVES, so the very first option is not announced until the user
+    // presses an arrow key. Asserted loosely here; tightened if cmdk fixes it.
+    const initial = input.getAttribute('aria-activedescendant');
+    expect([null, first]).toContain(initial);
+
+    await act(async () => {
+      fireEvent.keyDown(input, { key: 'ArrowDown' });
+    });
+    const second = selectedOptionId();
+    expect(second).toBeTruthy();
+    expect(second).not.toBe(first);
+    expect(input.getAttribute('aria-activedescendant')).toBe(second);
+    expect(document.activeElement).toBe(input);
+  });
+
+  it('marks the decorative icon aria-hidden and keeps the title as the option name', () => {
+    const registry = createRegistry();
+    registry.register(
+      defineCommand({
+        id: 'app.x.save',
+        title: 'Save file',
+        icon: '💾',
+        keybinding: '$mod+s',
+        execute: () => ok(0),
+      }),
+    );
+    render(<CommandPalette registry={registry} />);
+    const option = screen.getByRole('option');
+    expect(option.querySelector('[aria-hidden="true"]')?.textContent).toBe('💾');
+    // WCAG 2.5.3 Label in Name: the visible title is part of the option's text.
+    expect(option.textContent).toContain('Save file');
+  });
+
+  it('hands focus to the picker-chain input when an atomic parameterized command is chosen', async () => {
+    render(<CommandPalette registry={setup()} />);
+    await act(async () => {
+      fireEvent.click(screen.getByText('Set style').closest('[cmdk-item]')!);
+    });
+    const input = screen.getByRole('combobox');
+    expect(input.getAttribute('placeholder')).toBe('Pick variant…');
+    expect(document.activeElement).toBe(input);
+    // The step's own combobox is named for the parameter being collected.
+    const labelId = input.getAttribute('aria-labelledby');
+    expect(document.getElementById(labelId!)?.textContent).toBe('Pick variant');
+  });
+
+  it('focuses the text step input of a picker chain and names it', async () => {
+    const registry = createRegistry();
+    registry.register(
+      defineCommand({
+        id: 'app.graph.rename',
+        title: 'Rename node',
+        params: z.object({ label: z.string() }),
+        kind: 'atomic',
+        execute: (p) => ok(p),
+      }),
+    );
+    const { container } = render(<CommandPalette registry={registry} />);
+    await act(async () => {
+      fireEvent.click(screen.getByText('Rename node').closest('[cmdk-item]')!);
+    });
+    const text = container.querySelector<HTMLInputElement>('[data-acture-text-step]')!;
+    expect(document.activeElement).toBe(text);
+    expect(screen.getByRole('textbox', { name: 'label' })).toBe(text);
+  });
+
+  it('names a described parameter by the visible description (Label in Name)', async () => {
+    const registry = createRegistry();
+    registry.register(
+      defineCommand({
+        id: 'app.graph.relabel',
+        title: 'Relabel',
+        params: z.object({ label: z.string().describe('New node label') }),
+        kind: 'atomic',
+        execute: (p) => ok(p),
+      }),
+    );
+    render(<CommandPalette registry={registry} />);
+    await act(async () => {
+      fireEvent.click(screen.getByText('Relabel').closest('[cmdk-item]')!);
+    });
+    expect(screen.getByRole('textbox', { name: 'New node label' })).toBeTruthy();
+  });
+
+  it('announces a validation error on the text step', async () => {
+    const registry = createRegistry();
+    registry.register(
+      defineCommand({
+        id: 'app.graph.resize',
+        title: 'Resize',
+        params: z.object({ size: z.number().min(1) }),
+        kind: 'atomic',
+        execute: (p) => ok(p),
+      }),
+    );
+    const { container } = render(<CommandPalette registry={registry} />);
+    await act(async () => {
+      fireEvent.click(screen.getByText('Resize').closest('[cmdk-item]')!);
+    });
+    const text = container.querySelector<HTMLInputElement>('[data-acture-text-step]')!;
+    await act(async () => {
+      fireEvent.change(text, { target: { value: '0' } });
+      fireEvent.keyDown(text, { key: 'Enter' });
+    });
+    const alert = screen.getByRole('alert');
+    expect(alert.textContent).toBeTruthy();
+    expect(text.getAttribute('aria-invalid')).toBe('true');
+    expect(text.getAttribute('aria-describedby')).toBe(alert.id);
+  });
+
+  it('returns focus to the palette input when the picker chain is cancelled with Escape', async () => {
+    render(<CommandPalette registry={setup()} />);
+    await act(async () => {
+      fireEvent.click(screen.getByText('Set style').closest('[cmdk-item]')!);
+    });
+    await act(async () => {
+      fireEvent.keyDown(screen.getByRole('combobox'), { key: 'Escape' });
+    });
+    const input = screen.getByRole('combobox');
+    expect(input.getAttribute('placeholder')).toBe('Type a command…');
+    expect(document.activeElement).toBe(input);
+  });
+
+  it('mounts the form adapter in place of the list, then restores the list and its focus on cancel', async () => {
+    const FormAdapter: PaletteFormAdapter = ({ command, onCancel }) => (
+      <form aria-label={command.title}>
+        <input aria-label="Label" autoFocus />
+        <button type="button" onClick={onCancel}>cancel</button>
+      </form>
+    );
+    const { container } = render(<CommandPalette registry={setup()} formAdapter={FormAdapter} />);
+    await act(async () => {
+      fireEvent.click(screen.getByText('Add node').closest('[cmdk-item]')!);
+    });
+    // The list (and its combobox) is gone; the host form owns focus.
+    expect(screen.queryByRole('combobox')).toBeNull();
+    expect(container.querySelector('[data-acture-palette-view="form"]')).toBeTruthy();
+    expect(document.activeElement).toBe(screen.getByRole('textbox', { name: 'Label' }));
+
+    await act(async () => {
+      fireEvent.click(screen.getByText('cancel'));
+    });
+    const input = screen.getByRole('combobox');
+    expect(document.activeElement).toBe(input);
+  });
+});
diff --git a/packages/palette-react/src/picker-chain.tsx b/packages/palette-react/src/picker-chain.tsx
index 9da7e22..3442586 100644
--- a/packages/palette-react/src/picker-chain.tsx
+++ b/packages/palette-react/src/picker-chain.tsx
@@ -16,7 +16,7 @@
 /// <reference lib="dom" />
 
 import { Command } from 'cmdk';
-import { useState } from 'react';
+import { useId, useState } from 'react';
 import type { AnyCommandRecord } from 'acture';
 import { readEnumOptions, summarizeParams, unwrap } from './derive-kind.js';
 import type { ParamSummary } from './derive-kind.js';
@@ -159,6 +159,7 @@ function TextStep({ param, initial, onCommit, onBack }: StepProps): React.ReactE
     typeof initial === 'string' ? initial : initial === undefined ? '' : String(initial),
   );
   const [errorMsg, setErrorMsg] = useState<string | null>(null);
+  const errorId = useId();
 
   function submit(): void {
     const coerced = coerceFromText(draft, param);
@@ -176,6 +177,9 @@ function TextStep({ param, initial, onCommit, onBack }: StepProps): React.ReactE
       <input
         data-acture-text-step
         autoFocus
+        aria-label={paramLabel(param)}
+        aria-invalid={errorMsg ? true : undefined}
+        aria-describedby={errorMsg ? errorId : undefined}
         value={draft}
         placeholder={inferPlaceholder(param)}
         onChange={(e) => {
@@ -201,7 +205,7 @@ function TextStep({ param, initial, onCommit, onBack }: StepProps): React.ReactE
         }}
       />
       {errorMsg ? (
-        <span style={{ color: '#c33', fontSize: '0.85em' }} data-acture-validation-error>
+        <span id={errorId} role="alert" style={{ color: '#c33', fontSize: '0.85em' }} data-acture-validation-error>
           {errorMsg}
         </span>
       ) : null}