Address PR #1327 review: stable selectors, test polish, accessibility

- Add aria-label to Dropdowns in CreateCorpusActionModal (Trigger, Action
  Type, Fieldset, Analyzer) so tests can target via getByRole("combobox").
- Replace brittle .oc-dropdown__trigger.nth(N), .oc-modal, and
  textareas.nth(N) selectors in CreateCorpusActionModal.ct.tsx and
  CorpusAgentManagement.ct.tsx with stable getByRole / getByPlaceholder
  patterns.
- Document SYNC_CONTENT handler in CorpusChat.tsx: ASYNC_START is the
  only setter for isProcessing(true), so no reset is needed here.
- Comment the inline-agent happy-path mock to flag the dependency on
  the component's DEFAULT_MODERATOR_INSTRUCTIONS textarea default.
- Bump slow-mock loading-state test timeout 5s -> 10s for CI margin.
- Pin contract that unknown WebSocket frames leave the input enabled.

Author: JSv4

docs/assets/images/screenshots/auto/corpus--chat--conversation-list.png

@@ -468,6 +468,8 @@ export const CorpusChat: React.FC<CorpusChatProps> = ({
           case "SYNC_CONTENT": {
             // SYNC_CONTENT is a standalone (non-streaming) assistant reply — unlike the
             // ASYNC path, it must be appended to `chat` directly or it will never render.
+            // No setIsProcessing(false) is needed: ASYNC_START is the only setter for
+            // isProcessing(true), and SYNC_CONTENT arrives without a preceding ASYNC_START.
             setChat((prev) => [
               ...prev,
               {

docs/assets/images/screenshots/auto/corpus--chat--new-chat.png

@@ -581,6 +581,7 @@ export const CreateCorpusActionModal: React.FC<
           <label>Trigger</label>
           <Dropdown
             mode="select"
+            aria-label="Trigger"
             options={triggerOptions}
             value={trigger}
             onChange={(value) => {
@@ -620,6 +621,7 @@ export const CreateCorpusActionModal: React.FC<
           <label>Action Type</label>
           <Dropdown
             mode="select"
+            aria-label="Action Type"
             disabled={isThreadTrigger}
             options={actionTypeOptions}
             value={actionType}
@@ -674,6 +676,7 @@ export const CreateCorpusActionModal: React.FC<
               <label>Fieldset</label>
               <Dropdown
                 mode="select"
+                aria-label="Fieldset"
                 clearable
                 searchable="local"
                 options={fieldsetOptions}
@@ -713,6 +716,7 @@ export const CreateCorpusActionModal: React.FC<
               <label>Analyzer</label>
               <Dropdown
                 mode="select"
+                aria-label="Analyzer"
                 clearable
                 searchable="local"
                 options={analyzerOptions}

docs/assets/images/screenshots/auto/corpus--create-action-modal--fieldset-default.png

@@ -231,15 +231,21 @@ test.describe("CorpusAgentManagement", () => {
     // Fill the form
     await page.locator('input[placeholder="Agent name"]').fill("New Agent");
 
-    // The description and system instructions are textareas (the first two)
-    const textareas = page.locator("textarea");
-    await textareas.nth(0).fill("Some description");
-    await textareas.nth(1).fill("Be helpful.");
+    // Description + system-instructions textareas (placeholder-based, stable
+    // even if more textareas are added above them in the layout).
+    await page
+      .locator(
+        'textarea[placeholder="Brief description of what this agent does"]'
+      )
+      .fill("Some description");
+    await page
+      .locator('textarea[placeholder="System prompt for the agent..."]')
+      .fill("Be helpful.");
 
     // Submit (Create Agent button inside the modal footer)
     await page
-      .locator(".oc-modal button:has-text('Create Agent')")
-      .last()
+      .getByRole("dialog")
+      .getByRole("button", { name: "Create Agent", exact: true })
       .click();
 
     // Toast confirms creation
@@ -272,8 +278,8 @@ test.describe("CorpusAgentManagement", () => {
 
     // The Create Agent submit button (modal footer) should be disabled
     const submitBtn = page
-      .locator(".oc-modal button:has-text('Create Agent')")
-      .last();
+      .getByRole("dialog")
+      .getByRole("button", { name: "Create Agent", exact: true });
     await expect(submitBtn).toBeDisabled();
 
     await component.unmount();
@@ -431,7 +437,7 @@ test.describe("CorpusAgentManagement", () => {
     ).toBeVisible();
 
     // Click the read_doc ToolItem (monospace ToolName inside the modal)
-    await page.locator(".oc-modal").getByText("read_doc").first().click();
+    await page.getByRole("dialog").getByText("read_doc").first().click();
 
     // The info message should be gone now that there's a selected tool
     await expect(
@@ -461,7 +467,7 @@ test.describe("CorpusAgentManagement", () => {
     );
 
     await expect(page.getByText("Loading agents...")).toBeVisible({
-      timeout: 5000,
+      timeout: 10000,
     });
 
     await component.unmount();
@@ -666,13 +672,18 @@ test.describe("CorpusAgentManagement", () => {
     ).toBeVisible({ timeout: 5000 });
 
     await page.locator('input[placeholder="Agent name"]').fill("Buggy Agent");
-    const textareas = page.locator("textarea");
-    await textareas.nth(0).fill("Desc");
-    await textareas.nth(1).fill("Instr");
+    await page
+      .locator(
+        'textarea[placeholder="Brief description of what this agent does"]'
+      )
+      .fill("Desc");
+    await page
+      .locator('textarea[placeholder="System prompt for the agent..."]')
+      .fill("Instr");
 
     await page
-      .locator(".oc-modal button:has-text('Create Agent')")
-      .last()
+      .getByRole("dialog")
+      .getByRole("button", { name: "Create Agent", exact: true })
       .click();
 
     await expect(page.getByText("Slug collision detected")).toBeVisible({
@@ -702,15 +713,15 @@ test.describe("CorpusAgentManagement", () => {
     ).toBeVisible({ timeout: 5000 });
 
     // Select read_doc
-    await page.locator(".oc-modal").getByText("read_doc").first().click();
+    await page.getByRole("dialog").getByText("read_doc").first().click();
 
     // Selected pill is visible at the bottom
     await expect(
-      page.locator(".oc-modal").getByText("read_doc").nth(1)
+      page.getByRole("dialog").getByText("read_doc").nth(1)
     ).toBeVisible();
 
     // Deselect by clicking again
-    await page.locator(".oc-modal").getByText("read_doc").first().click();
+    await page.getByRole("dialog").getByText("read_doc").first().click();
 
     await expect(
       page.getByText(

docs/assets/images/screenshots/auto/corpus--description-editor--loaded.png

@@ -1084,6 +1084,8 @@ test.describe("CorpusChat", () => {
     await expect(
       page.getByText("Error connecting to the corpus WebSocket.")
     ).not.toBeVisible();
+    // Unknown frames must not stick the input in a processing state — pin it.
+    await expect(input).toBeEnabled({ timeout: 5000 });
 
     await component.unmount();
   });

frontend/src/components/corpuses/CorpusChat.tsx

@@ -523,8 +523,8 @@ test.describe("CreateCorpusActionModal", () => {
       .locator('input[placeholder="Enter action name"]')
       .fill("My Fieldset Action");
 
-    // Open the fieldset dropdown (third .oc-dropdown__trigger after trigger + actionType)
-    await page.locator(".oc-dropdown__trigger").nth(2).click();
+    // Open the fieldset dropdown
+    await page.getByRole("combobox", { name: "Fieldset" }).click();
     await page.getByText("Contract Fields", { exact: true }).click();
 
     // Submit
@@ -636,9 +636,8 @@ test.describe("CreateCorpusActionModal", () => {
       page.getByText("Create New Corpus Action", { exact: true })
     ).toBeVisible({ timeout: 20000 });
 
-    // Open the trigger dropdown (the first dropdown trigger in the modal)
-    const triggerDropdown = page.locator(".oc-dropdown__trigger").first();
-    await triggerDropdown.click();
+    // Open the trigger dropdown
+    await page.getByRole("combobox", { name: "Trigger" }).click();
     await page.getByText("On New Thread", { exact: true }).click();
 
     // Forced into agent action type with helper text
@@ -676,7 +675,7 @@ test.describe("CreateCorpusActionModal", () => {
     ).toBeVisible({ timeout: 20000 });
 
     // Switch to agent action type
-    await page.locator(".oc-dropdown__trigger").nth(1).click();
+    await page.getByRole("combobox", { name: "Action Type" }).click();
     await page.getByText("Agent (AI-powered action)").click();
 
     await expect(page.getByText("Agent Configuration")).toBeVisible({
@@ -718,7 +717,7 @@ test.describe("CreateCorpusActionModal", () => {
     ).toBeVisible({ timeout: 20000 });
 
     // Switch action type to agent
-    await page.locator(".oc-dropdown__trigger").nth(1).click();
+    await page.getByRole("combobox", { name: "Action Type" }).click();
     await page.getByText("Agent (AI-powered action)").click();
 
     await expect(page.getByText("Agent Configuration")).toBeVisible({
@@ -752,7 +751,7 @@ test.describe("CreateCorpusActionModal", () => {
     ).toBeVisible({ timeout: 20000 });
 
     // Switch action type to analyzer
-    await page.locator(".oc-dropdown__trigger").nth(1).click();
+    await page.getByRole("combobox", { name: "Action Type" }).click();
     await page.getByText("Analyzer (Run analysis)").click();
 
     await expect(page.getByText("Analyzer Configuration")).toBeVisible({
@@ -791,7 +790,7 @@ test.describe("CreateCorpusActionModal", () => {
       .fill("Outer action name");
 
     // Switch to agent
-    await page.locator(".oc-dropdown__trigger").nth(1).click();
+    await page.getByRole("combobox", { name: "Action Type" }).click();
     await page.getByText("Agent (AI-powered action)").click();
 
     await expect(page.getByText("Agent Configuration")).toBeVisible({
@@ -828,7 +827,7 @@ test.describe("CreateCorpusActionModal", () => {
     await page.locator('input[placeholder="Enter action name"]').fill("Outer");
 
     // Switch to agent
-    await page.locator(".oc-dropdown__trigger").nth(1).click();
+    await page.getByRole("combobox", { name: "Action Type" }).click();
     await page.getByText("Agent (AI-powered action)").click();
 
     await expect(page.getByText("Agent Configuration")).toBeVisible({
@@ -840,9 +839,10 @@ test.describe("CreateCorpusActionModal", () => {
       .locator('input[placeholder="e.g., Document Summarizer"]')
       .fill("Doc Agent");
 
-    // Clear the system-instructions textarea (it's the first of the three textareas)
-    const textareas = page.locator("textarea");
-    await textareas.nth(0).fill("");
+    // Clear the system-instructions textarea (document-trigger variant)
+    await page
+      .locator('textarea[placeholder*="Brief role description"]')
+      .fill("");
 
     await page
       .getByRole("button", { name: "Create Action", exact: true })
@@ -875,7 +875,7 @@ test.describe("CreateCorpusActionModal", () => {
       .fill("Pickless");
 
     // Switch action type to agent and then to "Use Existing Agent"
-    await page.locator(".oc-dropdown__trigger").nth(1).click();
+    await page.getByRole("combobox", { name: "Action Type" }).click();
     await page.getByText("Agent (AI-powered action)").click();
     await expect(page.getByText("Agent Configuration")).toBeVisible({
       timeout: 10000,
@@ -917,6 +917,9 @@ test.describe("CreateCorpusActionModal", () => {
           createAgentInline: true,
           inlineAgentName: "Inline Doc Agent",
           inlineAgentDescription: undefined,
+          // The component initializes the agent-instructions textarea with
+          // DEFAULT_MODERATOR_INSTRUCTIONS; this test does not fill it and
+          // relies on that default matching the mutation variable.
           inlineAgentInstructions: DEFAULT_MODERATOR_INSTRUCTIONS,
           inlineAgentTools: ["read_document_text", "update_document_summary"],
           disabled: false,
@@ -971,7 +974,7 @@ test.describe("CreateCorpusActionModal", () => {
       .fill("Inline Agent Action");
 
     // Switch action type to agent (inline mode is the default for doc triggers)
-    await page.locator(".oc-dropdown__trigger").nth(1).click();
+    await page.getByRole("combobox", { name: "Action Type" }).click();
     await page.getByText("Agent (AI-powered action)").click();
 
     await expect(page.getByText("Agent Configuration")).toBeVisible({
@@ -1053,7 +1056,7 @@ test.describe("CreateCorpusActionModal", () => {
       .locator('input[placeholder="Enter action name"]')
       .fill("Will Fail");
 
-    await page.locator(".oc-dropdown__trigger").nth(2).click();
+    await page.getByRole("combobox", { name: "Fieldset" }).click();
     await page.getByText("Contract Fields", { exact: true }).click();
 
     await page