🐛(frontend) fix outlook web handler in unquote logic (#754)

About the unquote-message logic, we encount a bug with a thread
implying Outlook Desktop quotes. Actually, for Outlook web we were looking for
a hr tag as quote separtor element. But sometimes this one can be wrap into a div
and we missed it.

src/frontend/src/features/utils/unquote-message/handlers.ts

@@ -143,15 +143,31 @@ export const HANDLERS: CustomHandler[] = [
       const normalizedStyle = style.replaceAll(/(cm|pt|mm)/g, "in");
 
       if (normalizedStyle.endsWith(" 1.0in;padding:3.0in 0in 0in 0in")) {
-        // Check if parent has only one element child
-        if (msoRoot.parentElement) {
-          const elementChildren = Array.from(
-            msoRoot.parentElement.childNodes
-          ).filter((node) => node.nodeType === Node.ELEMENT_NODE);
-
-          if (elementChildren.length === 1) {
-            msoRoot = msoRoot.parentElement as HTMLElement;
+        // The quoted content may live at an upper level: climb out of wrapper
+        // divs while the header has no following sibling, as long as nothing
+        // meaningful precedes it inside the wrapper (to avoid swallowing the
+        // new message content)
+        while (
+          msoRoot.parentElement &&
+          msoRoot.parentElement.tagName.toLowerCase() !== "body" &&
+          !msoRoot.nextElementSibling
+        ) {
+          // Use childNodes to also catch plain-text nodes, but only those
+          // preceding the header: text nodes following it belong to the quote
+          // and must not halt the climb
+          const siblings = Array.from(msoRoot.parentElement.childNodes);
+          const previousSiblings = siblings.slice(0, siblings.indexOf(msoRoot));
+          if (
+            previousSiblings.some(
+              (node) =>
+                (node.nodeType === Node.ELEMENT_NODE ||
+                  node.nodeType === Node.TEXT_NODE) &&
+                node.textContent?.trim()
+            )
+          ) {
+            break;
           }
+          msoRoot = msoRoot.parentElement;
         }
 
         // Collect all next siblings
@@ -175,7 +191,14 @@ export const HANDLERS: CustomHandler[] = [
       const detectedElements: HTMLElement[] = [];
       let prev = element.previousElementSibling;
       while (prev) {
-        if (prev.tagName.toLowerCase() === "hr") {
+        // Outlook renders the reply separator either as a bare <hr>
+        // or as an <hr> alone inside a centering div
+        const isSeparator =
+          prev.tagName.toLowerCase() === "hr" ||
+          (prev.children.length === 1 &&
+            prev.children[0].tagName.toLowerCase() === "hr" &&
+            !prev.textContent?.trim());
+        if (isSeparator) {
           // It's a reply from Outlook!
           detectedElements.push(element, prev as HTMLElement);
           let sibling = element.nextElementSibling;

src/frontend/src/features/utils/unquote-message/index.test.ts

@@ -375,6 +375,85 @@ describe("UnquoteMessage", () => {
         );
       });
 
+      it("should remove Microsoft Outlook Desktop quotes when the hr separator is wrapped in a div", () => {
+        const html = `
+          <div>My reply to the message</div>
+          <div class="MsoNormal" align="center" style="text-align:center"><hr size="3" width="98%" align="center"></div>
+          <div id="divRplyFwdMsg">
+            <b>De :</b> sender@example.com<br>
+            <b>Envoyé :</b> lundi 6 juillet 2026 15:45<br>
+            <b>À :</b> recipient@example.com<br>
+          </div>
+          <div>Original message body</div>
+        `;
+
+        const result = new UnquoteMessage(html).getHtml();
+
+        expect(result.hadQuotes).toBe(true);
+        expect(result.detectionMethod).toBe("handlers");
+        expect(result.content).toMatchInlineSnapshot(
+          `"<div>My reply to the message</div>"`
+        );
+      });
+
+      it("should remove Microsoft Outlook Web quotes when the header is nested in a wrapper and the body is a sibling of the wrapper", () => {
+        const html = `
+          <div>My reply</div>
+          <div>
+            <div id="content_out_sender_example.com"></div>
+            <div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
+              <p class="MsoNormal"><b>De :</b> sender@example.com</p>
+            </div>
+          </div>
+          <div>Original message body</div>
+        `;
+
+        const result = new UnquoteMessage(html).getHtml();
+
+        expect(result.hadQuotes).toBe(true);
+        expect(result.detectionMethod).toBe("handlers");
+        expect(result.content).toMatchInlineSnapshot(
+          `"<div>My reply</div>"`
+        );
+      });
+
+      it("should not swallow a plain-text reply preceding the Microsoft Outlook Web header inside a wrapper", () => {
+        const html = `
+          <div>
+            My plain-text reply
+            <div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
+              <p class="MsoNormal"><b>De :</b> sender@example.com</p>
+            </div>
+          </div>
+        `;
+
+        const result = new UnquoteMessage(html).getHtml();
+
+        expect(result.hadQuotes).toBe(true);
+        expect(result.content).toContain("My plain-text reply");
+        expect(result.content).not.toContain("sender@example.com");
+      });
+
+      it("should keep climbing when only quoted text nodes follow the Microsoft Outlook Web header", () => {
+        const html = `
+          <div>My reply</div>
+          <div>
+            <div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
+              <p class="MsoNormal"><b>De :</b> sender@example.com</p>
+            </div>
+            Quoted text node
+          </div>
+          <div>Original message body</div>
+        `;
+
+        const result = new UnquoteMessage(html).getHtml();
+
+        expect(result.hadQuotes).toBe(true);
+        expect(result.content).toMatchInlineSnapshot(
+          `"<div>My reply</div>"`
+        );
+      });
+
       it("should remove ZMail quotes with zmail_extra", () => {
         const html = `
           <div>New message</div>