feat(message): add the Message family

e2e/fixtures.tsx

@@ -51,6 +51,13 @@ import {
   groupActivity,
   type PartTool,
   type ToolApprovalRecord,
+  Message,
+  MessageAction,
+  MessageActionMenu,
+  MessageActions,
+  MessageContent,
+  MessageFold,
+  MessageFooter,
 } from "@corbits/react-ui";
 import {
   CommandPalette,
@@ -817,6 +824,121 @@ function ToolApprovalScenario() {
   );
 }
 
+/** A long answer: 40 paragraphs of fixed-height lines, past the fold. */
+const FOLD_PARAGRAPHS = Array.from(
+  { length: 40 },
+  (_, index) => `Paragraph ${index + 1} of a long answer.`,
+);
+const FOLD_LENGTH = 10_000;
+
+function FoldedAnswer() {
+  return (
+    <Message from="agent" data-testid="long-answer">
+      <MessageFold length={FOLD_LENGTH}>
+        <MessageContent>
+          {FOLD_PARAGRAPHS.map((text) => (
+            <p key={text} style={{ height: 48, margin: 0 }}>
+              {text}
+            </p>
+          ))}
+        </MessageContent>
+      </MessageFold>
+    </Message>
+  );
+}
+
+/** A long answer between other rows, in a plain scroll container. */
+function MessageFoldScenario() {
+  return (
+    <div
+      data-testid="scroller"
+      style={{ height: 400, width: 600, overflowY: "auto" }}
+    >
+      <p style={{ height: 600, margin: 0 }}>Before</p>
+      <FoldedAnswer />
+      <p style={{ height: 600, margin: 0 }}>After</p>
+    </div>
+  );
+}
+
+/** The same answer inside a conversation, which anchors its own scrolling. */
+function MessageFoldConversationScenario({
+  policy,
+}: {
+  policy: ConversationScrollPolicy;
+}) {
+  return (
+    <div
+      style={{
+        display: "flex",
+        flexDirection: "column",
+        height: 400,
+        width: 600,
+      }}
+    >
+      <Conversation scrollPolicy={policy}>
+        <ConversationContent data-testid="scroller">
+          {historyRows("h", 10).map((row) => (
+            <ConversationItem key={row.id} itemId={row.id}>
+              <p style={{ height: row.lines * 24, margin: 0 }}>Row {row.id}</p>
+            </ConversationItem>
+          ))}
+          <ConversationItem itemId="long">
+            <FoldedAnswer />
+          </ConversationItem>
+          {historyRows("t", 10).map((row) => (
+            <ConversationItem key={row.id} itemId={row.id}>
+              <p style={{ height: row.lines * 24, margin: 0 }}>Row {row.id}</p>
+            </ConversationItem>
+          ))}
+        </ConversationContent>
+      </Conversation>
+    </div>
+  );
+}
+
+function ActionRow({ record }: { record: (event: string) => void }) {
+  return (
+    <MessageActions>
+      <MessageAction label="Copy" onClick={() => record("copy")} />
+      <MessageActionMenu>
+        <MessageAction label="Pin" onClick={() => record("pin")} />
+        <MessageAction label="Copy link" onClick={() => record("link")} />
+        <MessageAction label="Report" onClick={() => record("report")} />
+      </MessageActionMenu>
+    </MessageActions>
+  );
+}
+
+/** An action row at the top of the page, and one at the foot of a short
+ * scroll container where a menu opening downwards would be clipped. */
+function MessageActionsScenario() {
+  const { log, record } = useEventLog();
+  return (
+    <div style={{ width: 480 }}>
+      <Message from="agent" data-testid="top">
+        <MessageContent text="An answer with actions." />
+        <MessageFooter>
+          <ActionRow record={record} />
+        </MessageFooter>
+      </Message>
+      <button type="button">After</button>
+      <div
+        data-testid="clipped"
+        style={{ height: 240, overflowY: "auto", marginTop: 24 }}
+      >
+        <div style={{ height: 200 }} />
+        <Message from="agent" data-testid="bottom">
+          <MessageFooter>
+            <ActionRow record={record} />
+          </MessageFooter>
+        </Message>
+      </div>
+      {log}
+    </div>
+  );
+}
+
 export const scenarios: Record<string, () => ReactNode> = {
   smoke: () => <Button>Ready</Button>,
   "approval-card": () => <Approval state="idle" />,
@@ -855,4 +977,12 @@ export const scenarios: Record<string, () => ReactNode> = {
   "prompt-input-toolbar": () => <PromptToolbarScenario />,
   "panel-tabs": () => <PanelTabsScenario />,
   "tool-approval": () => <ToolApprovalScenario />,
+  "message-fold": () => <MessageFoldScenario />,
+  "message-fold-settle": () => (
+    <MessageFoldConversationScenario policy="settle" />
+  ),
+  "message-fold-stick": () => (
+    <MessageFoldConversationScenario policy="stick" />
+  ),
+  "message-actions": () => <MessageActionsScenario />,
 };

e2e/message.spec.ts

@@ -0,0 +1,181 @@
+import { expect, test, type Locator, type Page } from "@playwright/test";
+
+const scroller = (page: Page) => page.getByTestId("scroller");
+
+const toggle = (page: Page) =>
+  page.locator("[data-slot='message-fold-toggle']");
+
+/** How far the fold control sits below the top of the scroll container. */
+const toggleOffset = async (page: Page) => {
+  const box = await scroller(page).evaluate(
+    (element) => element.getBoundingClientRect().top,
+  );
+  const top = await toggle(page).evaluate(
+    (element) => element.getBoundingClientRect().top,
+  );
+  return top - box;
+};
+
+/** Waits for the container to stop moving. */
+const settled = async (page: Page) => {
+  let previous = Number.NaN;
+  await expect
+    .poll(
+      async () => {
+        const top = await scroller(page).evaluate(
+          (element) => element.scrollTop,
+        );
+        const still = top === previous;
+        previous = top;
+        return still;
+      },
+      { intervals: [100] },
+    )
+    .toBe(true);
+};
+
+/** Scrolls as the reader would, with the wheel, to put `contentTop` (a
+ * position inside the answer) at the top of the view. */
+const readInto = async (page: Page, contentTop: number) => {
+  const answerTop = await page
+    .getByTestId("long-answer")
+    .evaluate((element, scrollerTop) => {
+      const container = element.closest("[data-testid='scroller']");
+      if (container === null) throw new Error("expected the scroller");
+      return (
+        element.getBoundingClientRect().top -
+        container.getBoundingClientRect().top +
+        container.scrollTop -
+        scrollerTop
+      );
+    }, 0);
+  const current = await scroller(page).evaluate((element) => element.scrollTop);
+  const box = await scroller(page).boundingBox();
+  if (box === null) throw new Error("expected the scroller on screen");
+  await page.mouse.move(box.x + box.width / 2, box.y + box.height / 2);
+  await page.mouse.wheel(0, answerTop + contentTop - current);
+  await settled(page);
+};
+
+/** Opens the answer, reads into the middle of it, and folds it from there:
+ * the control must stay where it was on screen. */
+const foldFromInside = async (page: Page) => {
+  await toggle(page).click();
+  await expect(toggle(page)).toHaveAttribute("aria-expanded", "true");
+  await readInto(page, 900);
+  const before = await toggleOffset(page);
+  const height = await scroller(page).evaluate(
+    (element) => element.clientHeight,
+  );
+  // Open, the control rides the bottom of the view while the answer is read.
+  expect(before).toBeGreaterThan(height / 2);
+  expect(before).toBeLessThan(height);
+
+  await toggle(page).click();
+  await expect(toggle(page)).toHaveAttribute("aria-expanded", "false");
+  await settled(page);
+  const after = await toggleOffset(page);
+  expect(Math.abs(after - before)).toBeLessThanOrEqual(1);
+};
+
+test("folding an answer from inside it keeps the reader's place", async ({
+  page,
+}) => {
+  await page.goto("/message-fold");
+  await expect(toggle(page)).toHaveText(/Show full answer/);
+  await foldFromInside(page);
+});
+
+for (const policy of ["settle", "stick"]) {
+  test(`folding inside a conversation (${policy}) keeps the reader's place`, async ({
+    page,
+  }) => {
+    await page.goto(`/message-fold-${policy}`);
+    await expect(toggle(page)).toBeAttached();
+    await foldFromInside(page);
+  });
+}
+
+const row = (page: Page, id: string) => page.getByTestId(id);
+const trigger = (scope: Locator) =>
+  scope.getByRole("button", { name: "More actions" });
+const menu = (scope: Locator) =>
+  scope.getByRole("menu", { name: "More actions" });
+const item = (scope: Locator, name: string) =>
+  scope.getByRole("menuitem", { name });
+
+test("the overflow menu works from the keyboard and returns focus", async ({
+  page,
+}) => {
+  await page.goto("/message-actions");
+  const top = row(page, "top");
+  await trigger(top).focus();
+  await page.keyboard.press("Enter");
+  await expect(menu(top)).toBeVisible();
+  await expect(trigger(top)).toHaveAttribute("aria-expanded", "true");
+  await expect(item(top, "Pin")).toBeFocused();
+
+  await page.keyboard.press("ArrowDown");
+  await expect(item(top, "Copy link")).toBeFocused();
+  await page.keyboard.press("ArrowDown");
+  await page.keyboard.press("ArrowDown");
+  await expect(item(top, "Pin")).toBeFocused();
+  await page.keyboard.press("ArrowUp");
+  await expect(item(top, "Report")).toBeFocused();
+  await page.keyboard.press("Home");
+  await expect(item(top, "Pin")).toBeFocused();
+  await page.keyboard.press("End");
+  await expect(item(top, "Report")).toBeFocused();
+
+  await page.keyboard.press("Escape");
+  await expect(menu(top)).toHaveCount(0);
+  await expect(trigger(top)).toBeFocused();
+  await expect(trigger(top)).toHaveAttribute("aria-expanded", "false");
+});
+
+test("ArrowUp on the trigger opens the menu on its last item", async ({
+  page,
+}) => {
+  await page.goto("/message-actions");
+  const top = row(page, "top");
+  await trigger(top).focus();
+  await page.keyboard.press("ArrowUp");
+  await expect(item(top, "Report")).toBeFocused();
+});
+
+test("choosing an item runs it, closes the menu and refocuses the trigger", async ({
+  page,
+}) => {
+  await page.goto("/message-actions");
+  const top = row(page, "top");
+  await trigger(top).focus();
+  await page.keyboard.press("ArrowDown");
+  await page.keyboard.press("ArrowDown");
+  await page.keyboard.press("Enter");
+  await expect(page.getByRole("status", { name: "Events" })).toHaveText("link");
+  await expect(menu(top)).toHaveCount(0);
+  await expect(trigger(top)).toBeFocused();
+});
+
+test("focus leaving the menu closes it", async ({ page }) => {
+  await page.goto("/message-actions");
+  const top = row(page, "top");
+  await trigger(top).click();
+  await expect(item(top, "Pin")).toBeFocused();
+  await page.keyboard.press("Tab");
+  await expect(menu(top)).toHaveCount(0);
+});
+
+test("a menu that would be clipped below opens above", async ({ page }) => {
+  await page.goto("/message-actions");
+  const bottom = row(page, "bottom");
+  await trigger(bottom).click();
+  const content = menu(bottom);
+  await expect(content).toBeVisible();
+  await expect(content).toHaveAttribute("data-side", "top");
+  const clip = await page.getByTestId("clipped").boundingBox();
+  const box = await content.boundingBox();
+  if (clip === null || box === null) throw new Error("expected both boxes");
+  expect(box.y).toBeGreaterThanOrEqual(clip.y);
+  expect(box.y + box.height).toBeLessThanOrEqual(clip.y + clip.height);
+});