test(e2e): repair investigation textarea selectors

tests/e2e/long-investigation.spec.js

@@ -59,7 +59,7 @@ async function waitForWorkspaceReady(page, options = {}) {
  * Returns { success, hasError } for test assertions.
  */
 async function submitAnswer(page, text) {
-  const textarea = page.locator('textarea[placeholder*=Answer]');
+  const textarea = page.locator('[data-testid="response-textarea"]');
   if (!(await textarea.isVisible({ timeout: 3000 }).catch(() => false))) {
     return { success: false, hasError: false };
   }
@@ -90,7 +90,7 @@ test("long investigation — European market entry with 4 answer turns", async (
     window.__MOCK_SCENARIO = "complete";
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(LONG_INVESTIGATION.centralStatement);
   await page.getByRole("button", { name: "Analyse" }).click();
 
@@ -133,7 +133,7 @@ test("contradiction fixture — opposing recommendations in investigation card",
     window.__MOCK_SCENARIO = ""; // use default
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(CONTRADICTION.centralStatement);
   await page.getByRole("button", { name: "Analyse" }).click();
 
@@ -173,7 +173,7 @@ test("diagnosis scenario — churn investigation renders correctly", async ({ pa
     window.__MOCK_SCENARIO = "";
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(DIAGNOSIS.centralStatement);
   await page.getByRole("button", { name: "Analyse" }).click();
 
@@ -204,7 +204,7 @@ test("comparison scenario — product rating nodes render with edges", async ({
     window.__MOCK_SCENARIO = "";
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(COMPARISON.centralStatement);
   await page.getByRole("button", { name: "Analyse" }).click();
 
@@ -218,7 +218,7 @@ test("comparison scenario — product rating nodes render with edges", async ({
 
   if (result.success) {
     // Second turn's answer textarea should appear
-    const answerTextarea = page.locator('textarea[placeholder*=Answer]');
+    const answerTextarea = page.locator('[data-testid="response-textarea"]');
     expect(await answerTextarea.isVisible()).toBe(true);
 
     // Submit second answer
@@ -240,7 +240,7 @@ test("prioritisation scenario — team relocation yields ranked options", async
     window.__MOCK_SCENARIO = "";
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(PRIORITISATION.centralStatement);
   await page.getByRole("button", { name: "Analyse" }).click();
 
@@ -270,7 +270,7 @@ test("rapid successive updates maintain correct loading-state cycling", async ({
     window.__MOCK_SCENARIO = "";
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(LONG_INVESTIGATION.centralStatement); // use long scenario central statement
   await page.getByRole("button", { name: "Analyse" }).click();
 
@@ -302,19 +302,19 @@ test("answer textarea placeholder updates between turns", async ({ page }) => {
     window.__MOCK_SCENARIO = "";
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(INVESTIGATION_SCENARIOS[0].centralStatement);
   await page.getByRole("button", { name: "Analyse" }).click();
 
   // Initial workspace should have an answer textarea with a question-related placeholder
-  const answerTextarea = page.locator('textarea[placeholder*=Answer]');
+  const answerTextarea = page.locator('[data-testid="response-textarea"]');
   await expect(answerTextarea).toBeVisible({ timeout: 10_000 });
 
   // Submit first answer
   await submitAnswer(page, INVESTIGATION_SCENARIOS[0].answerSequence[0]?.text || "");
 
   // After update, new question textarea should be present with potentially different placeholder
-  const updatedTextarea = page.locator('textarea[placeholder*=Answer]');
+  const updatedTextarea = page.locator('[data-testid="response-textarea"]');
   await expect(updatedTextarea).toBeVisible();
 
   // The workspace card should still display the current investigation context
@@ -334,7 +334,7 @@ test("terminal state renders without answer textarea", async ({ page }) => {
     window.__MOCK_SCENARIO = "complete";
   });
 
-  const textarea = page.locator("textarea[placeholder*=Describe]");
+  const textarea = page.locator('[data-testid="scenario-textarea"]');
   await textarea.fill(SCENARIO_LOOKUP["Happy path — complete investigation"].centralStatement);
   await page.getByRole("button", { name: "Analyse" }).click();
 
@@ -344,7 +344,7 @@ test("terminal state renders without answer textarea", async ({ page }) => {
   await expect(page.locator('[data-testid="reasoning-workspace"]')).toBeVisible();
 
   // If there's a question (turn 0 gives a question), submit it to reach terminal
-  const answerTextarea = page.locator('textarea[placeholder*=Answer]');
+  const answerTextarea = page.locator('[data-testid="response-textarea"]');
   if (await answerTextarea.isVisible({ timeout: 3000 })) {
     await answerTextarea.fill(SCENARIO_LOOKUP["Happy path — complete investigation"].answerSequence[0]?.text || "");
     await page.getByRole("button", { name: "Update situation" }).click();