diff --git a/locales/en-US/browser/browser/zen-general.ftl b/locales/en-US/browser/browser/zen-general.ftl
index d1229b04f..c1a4efa7c 100644
--- a/locales/en-US/browser/browser/zen-general.ftl
+++ b/locales/en-US/browser/browser/zen-general.ftl
@@ -19,13 +19,19 @@ tab-context-zen-add-essential-badge = { $num } / { $max }
 tab-context-zen-remove-essential =
     .label = Remove from Essentials
     .accesskey = R
-tab-context-zen-replace-pinned-url-with-current =
+tab-context-zen-edit-pinned-page =
     .label =
         { $isEssential ->
-            [true] Replace Essential URL with Current
-           *[false] Replace Pinned URL with Current
+            [true] Edit Essential URL
+           *[false] Edit Pinned URL
         }
+    .accesskey = P
+tab-context-zen-replace-pinned-url-with-current =
+    .label = Replace with Current URL
     .accesskey = C
+tab-context-zen-edit-pinned-url =
+    .label = Edit...
+    .accesskey = E
 tab-context-zen-edit-title =
     .label = Change Label...
 tab-context-zen-edit-icon =
@@ -55,6 +61,10 @@ zen-general-confirm =
     .label = Confirm
 
 zen-pinned-tab-replaced = Pinned tab URL has been replaced with the current URL!
+zen-pinned-tab-url-edited = Pinned tab URL has been updated!
+zen-pinned-tab-url-invalid = That doesn't look like a valid URL.
+zen-pinned-tab-edit-url-title = Edit Pinned URL
+zen-pinned-tab-edit-url-label = Enter the URL this pinned tab should point to:
 zen-tabs-renamed = Tab has been successfully renamed!
 zen-background-tab-opened-toast = New background tab opened!
 zen-workspace-renamed-toast = Workspace has been successfully renamed!
diff --git a/src/browser/base/content/zen-commands.inc.xhtml b/src/browser/base/content/zen-commands.inc.xhtml
index 2122c56f0..3019feaca 100644
--- a/src/browser/base/content/zen-commands.inc.xhtml
+++ b/src/browser/base/content/zen-commands.inc.xhtml
@@ -35,6 +35,7 @@
   <command id="cmd_zenToggleTabsOnRight" />
 
   <command id="cmd_zenReplacePinnedUrlWithCurrent" />
+  <command id="cmd_zenEditPinnedUrl" />
   <command id="cmd_contextZenAddToEssentials" />
   <command id="cmd_contextZenRemoveFromEssentials" />
 
diff --git a/src/zen/common/zen-sets.js b/src/zen/common/zen-sets.js
index 289dbe9eb..e9fecea05 100644
--- a/src/zen/common/zen-sets.js
+++ b/src/zen/common/zen-sets.js
@@ -78,6 +78,9 @@ document.addEventListener(
           case "cmd_zenReplacePinnedUrlWithCurrent":
             gZenPinnedTabManager.replacePinnedUrlWithCurrent();
             break;
+          case "cmd_zenEditPinnedUrl":
+            gZenPinnedTabManager.editPinnedUrl();
+            break;
           case "cmd_contextZenAddToEssentials":
             gZenPinnedTabManager.addToEssentials();
             break;
diff --git a/src/zen/sessionstore/ZenWindowSync.sys.mjs b/src/zen/sessionstore/ZenWindowSync.sys.mjs
index 0d4ad78ec..f4f993923 100644
--- a/src/zen/sessionstore/ZenWindowSync.sys.mjs
+++ b/src/zen/sessionstore/ZenWindowSync.sys.mjs
@@ -1232,19 +1232,38 @@ class nsZenWindowSync {
       activeIndex = Math.min(activeIndex, entries.length - 1);
       activeIndex = Math.max(activeIndex, 0);
       let entryToUse = (entries[activeIndex] || entries[0]) ?? null;
-      const initialState = {
-        entry: {
-          url: entryToUse?.url,
-          title: entryToUse?.title,
-        },
-        image,
-      };
-      this.#runOnAllWindows(null, win => {
-        const targetTab = this.getItemFromWindow(win, aTab.id);
-        if (targetTab) {
-          targetTab._zenPinnedInitialState = initialState;
-        }
-      });
+      this.#setPinnedInitialState(
+        aTab,
+        { url: entryToUse?.url, title: entryToUse?.title },
+        image
+      );
+    });
+  }
+
+  /**
+   * Sets the canonical pinned URL for a tab across all windows. Used to let the
+   * user edit a pinned tab's URL directly.
+   *
+   * @param {object} aTab - The tab to set the pinned URL for.
+   * @param {string} aUrl - The URL to store as the canonical pinned URL.
+   * @param {string} [aImage] - Optional Icon to store.
+   */
+  setPinnedUrl(aTab, aUrl, aImage) {
+    this.log(`Setting pinned url for tab ${aTab.id}`);
+    this.#setPinnedInitialState(
+      aTab,
+      { url: aUrl, title: aTab.zenStaticLabel },
+      aImage
+    );
+  }
+
+  #setPinnedInitialState(aTab, aEntry, aImage) {
+    const initialState = { entry: aEntry, image: aImage };
+    this.#runOnAllWindows(null, win => {
+      const targetTab = this.getItemFromWindow(win, aTab.id);
+      if (targetTab) {
+        targetTab._zenPinnedInitialState = initialState;
+      }
     });
   }
 
diff --git a/src/zen/tabs/ZenPinnedTabManager.mjs b/src/zen/tabs/ZenPinnedTabManager.mjs
index b2adb121f..4a441f8b2 100644
--- a/src/zen/tabs/ZenPinnedTabManager.mjs
+++ b/src/zen/tabs/ZenPinnedTabManager.mjs
@@ -246,6 +246,66 @@ class nsZenPinnedTabManager extends nsZenDOMOperatedFeature {
     gZenUIManager.showToast("zen-pinned-tab-replaced");
   }
 
+  async editPinnedUrl(tab = undefined) {
+    tab ??= TabContextMenu.contextTab;
+    if (!tab || !tab.pinned) {
+      return;
+    }
+
+    const initialUrl =
+      tab._zenPinnedInitialState?.entry?.url ||
+      tab.linkedBrowser?.currentURI?.spec;
+    const [title, label] = await document.l10n.formatValues([
+      { id: "zen-pinned-tab-edit-url-title" },
+      { id: "zen-pinned-tab-edit-url-label" },
+    ]);
+    const result = { value: initialUrl ?? "" };
+    const confirmed = Services.prompt.prompt(
+      window,
+      title,
+      label,
+      result,
+      null,
+      { value: false }
+    );
+    if (!confirmed) {
+      return;
+    }
+
+    let uri;
+    try {
+      uri = Services.uriFixup.getFixupURIInfo(
+        result.value.trim(),
+        Ci.nsIURIFixup.FIXUP_FLAG_FIX_SCHEME_TYPOS
+      ).preferredURI;
+    } catch (_) {}
+    if (!uri) {
+      gZenUIManager.showToast("zen-pinned-tab-url-invalid");
+      return;
+    }
+    const url = uri.spec;
+
+    // Skip when the value wasn't actually changed from what was prefilled.
+    if (!url || url === initialUrl) {
+      return;
+    }
+
+    const image = tab.zenStaticIcon || (await this.#getCachedFavicon(uri));
+    window.gZenWindowSync.setPinnedUrl(tab, url, image);
+    this.#resetTabToStoredState(tab);
+    gZenUIManager.showToast("zen-pinned-tab-url-edited");
+  }
+
+  async #getCachedFavicon(uri) {
+    try {
+      const favicon = await PlacesUtils.favicons.getFaviconForPage(uri);
+      return favicon?.dataURI?.spec;
+    } catch (ex) {
+      console.error("Failed to get favicon for edited pinned url:", ex);
+      return null;
+    }
+  }
+
   _initClosePinnedTabShortcut() {
     let cmdClose = document.getElementById("cmd_close");
 
@@ -545,11 +605,20 @@ class nsZenPinnedTabManager extends nsZenDOMOperatedFeature {
     }
     const elements = window.MozXULElement.parseXULToFragment(`
             <menuseparator id="context_zen-pinned-tab-separator" hidden="true"/>
-            <menuitem id="context_zen-replace-pinned-url-with-current"
-                      data-lazy-l10n-id="tab-context-zen-replace-pinned-url-with-current"
-                      data-l10n-args="{&quot;isEssential&quot;:&quot;&quot;}"
-                      hidden="true"
-                      command="cmd_zenReplacePinnedUrlWithCurrent"/>
+            <menu id="context_zen-edit-pinned-page"
+                  data-lazy-l10n-id="tab-context-zen-edit-pinned-page"
+                  data-l10n-args="{&quot;isEssential&quot;:&quot;&quot;}"
+                  hidden="true">
+              <menupopup>
+                <menuitem id="context_zen-replace-pinned-url-with-current"
+                          data-lazy-l10n-id="tab-context-zen-replace-pinned-url-with-current"
+                          data-l10n-args="{&quot;isEssential&quot;:&quot;&quot;}"
+                          command="cmd_zenReplacePinnedUrlWithCurrent"/>
+                <menuitem id="context_zen-edit-pinned-url"
+                          data-lazy-l10n-id="tab-context-zen-edit-pinned-url"
+                          command="cmd_zenEditPinnedUrl"/>
+              </menupopup>
+            </menu>
             <menuitem id="context_zen-reset-pinned-tab"
                       data-lazy-l10n-id="tab-context-zen-reset-pinned-tab"
                       data-l10n-args="{&quot;isEssential&quot;:&quot;&quot;}"
@@ -619,15 +688,24 @@ class nsZenPinnedTabManager extends nsZenDOMOperatedFeature {
     const zenResetPinnedTab = document.getElementById(
       "context_zen-reset-pinned-tab"
     );
+    const zenEditPinnedPage = document.getElementById(
+      "context_zen-edit-pinned-page"
+    );
     const zenReplacePinnedUrl = document.getElementById(
       "context_zen-replace-pinned-url-with-current"
     );
-    [zenResetPinnedTab, zenReplacePinnedUrl].forEach(element => {
+    [zenResetPinnedTab, zenEditPinnedPage].forEach(element => {
       if (element) {
         element.hidden = !isVisible;
-        document.l10n.setArgs(element, { isEssential });
       }
     });
+    [zenResetPinnedTab, zenEditPinnedPage, zenReplacePinnedUrl].forEach(
+      element => {
+        if (element) {
+          document.l10n.setArgs(element, { isEssential });
+        }
+      }
+    );
     zenAddEssential.hidden = isEssential || !!contextTab.group;
     document.l10n
       .formatValue("tab-context-zen-add-essential-badge", {
@@ -857,7 +935,7 @@ class nsZenPinnedTabManager extends nsZenDOMOperatedFeature {
     ) {
       return;
     }
-    // Remove # and ? from the URL
+    // Remove # from the URL
     const pinUrl = tab._zenPinnedInitialState.entry.url.split("#")[0];
     const currentUrl = location.split("#")[0];
     // Add an indicator that the pin has been changed
@@ -897,10 +975,14 @@ class nsZenPinnedTabManager extends nsZenDOMOperatedFeature {
     } else {
       tab.setAttribute("zen-pinned-changed", "true");
     }
-    tab.style.setProperty(
-      "--zen-original-tab-icon",
-      `url(${tab._zenPinnedInitialState.image})`
-    );
+    if (tab._zenPinnedInitialState.image) {
+      tab.style.setProperty(
+        "--zen-original-tab-icon",
+        `url(${tab._zenPinnedInitialState.image})`
+      );
+    } else {
+      tab.style.removeProperty("--zen-original-tab-icon");
+    }
   }
 
   removeTabContainersDragoverClass(hideIndicator = true) {
diff --git a/src/zen/tests/pinned/browser.toml b/src/zen/tests/pinned/browser.toml
index fb11e91bb..8cdc130e8 100644
--- a/src/zen/tests/pinned/browser.toml
+++ b/src/zen/tests/pinned/browser.toml
@@ -13,6 +13,8 @@ prefs = ["zen.workspaces.separate-essentials=false"]
 
 ["browser_pinned_created.js"]
 
+["browser_pinned_edit_url.js"]
+
 ["browser_pinned_nounload_reset.js"]
 
 ["browser_pinned_reset_button.js"]
diff --git a/src/zen/tests/pinned/browser_pinned_edit_url.js b/src/zen/tests/pinned/browser_pinned_edit_url.js
new file mode 100644
index 000000000..dae86fa9e
--- /dev/null
+++ b/src/zen/tests/pinned/browser_pinned_edit_url.js
@@ -0,0 +1,384 @@
+/* Any copyright is dedicated to the Public Domain.
+   https://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+async function pinTab(url) {
+  const tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, url);
+  gBrowser.pinTab(tab);
+  await gBrowser.TabStateFlusher.flush(tab.linkedBrowser);
+  // eslint-disable-next-line mozilla/no-arbitrary-setTimeout
+  await new Promise(r => setTimeout(r, 500));
+  return tab;
+}
+
+// XPCOM service methods can't be stubbed in place (non-configurable), so we
+// swap the whole service object out for a mock and restore it afterwards.
+function mockPrompt(value) {
+  const original = Services.prompt;
+  Services.prompt = {
+    QueryInterface: ChromeUtils.generateQI([Ci.nsIPromptService]),
+    prompt(win, title, label, result) {
+      if (value === null) {
+        return false; // user cancelled
+      }
+      result.value = value;
+      return true;
+    },
+  };
+  return () => {
+    Services.prompt = original;
+  };
+}
+
+function mockFavicons(faviconSpec) {
+  const original = PlacesUtils.favicons;
+  const mock = {
+    callCount: 0,
+    defaultFavicon: { spec: "data:image/png;base64,DEFAULT" },
+    getFaviconForPage() {
+      mock.callCount++;
+      return Promise.resolve(
+        faviconSpec ? { dataURI: { spec: faviconSpec } } : null
+      );
+    },
+  };
+  PlacesUtils.favicons = mock;
+  return {
+    mock,
+    restore: () => {
+      PlacesUtils.favicons = original;
+    },
+  };
+}
+
+add_task(async function test_EditPinnedUrl_SurvivesRebuild() {
+  // Pinned tab at url1 (loaded), then select a different tab (unfocus it).
+  const tab = await pinTab("https://example.com/1");
+  const other = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "https://example.com/other"
+  );
+
+  const editedUrl = "https://example.com/edited";
+  const restorePrompt = mockPrompt(editedUrl);
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    // Close + re-open rebuilds the tab: the in-memory _zenPinnedInitialState is
+    // gone and gets reconstructed from the persisted session via
+    // setPinnedTabState (exactly what #onSessionStoreInitialized does).
+    delete tab._zenPinnedInitialState;
+    await window.gZenWindowSync.setPinnedTabState(tab);
+
+    Assert.equal(
+      tab._zenPinnedInitialState.entry.url,
+      editedUrl,
+      "After the tab is rebuilt, the pinned URL should still be the edited one"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(other);
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_ActiveTabNavigates() {
+  // Editing the active (focused) pinned tab applies the new URL immediately:
+  // the live tab navigates to it (matching Arc's behavior).
+  const tab = await pinTab("https://example.com/1");
+  Assert.equal(gBrowser.selectedTab, tab, "the pinned tab should be active");
+
+  const editedUrl = "https://example.com/edited";
+  const restorePrompt = mockPrompt(editedUrl);
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+    await BrowserTestUtils.waitForCondition(
+      () => tab.linkedBrowser.currentURI.spec === editedUrl,
+      "the active pinned tab to navigate to the edited URL"
+    );
+
+    Assert.equal(
+      tab.linkedBrowser.currentURI.spec,
+      editedUrl,
+      "Editing the active pinned tab should navigate it to the new URL"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(
+  async function test_EditPinnedUrl_FaviconLookupErrorLeavesImageEmpty() {
+    const tab = await pinTab("https://example.com/1");
+    const restorePrompt = mockPrompt("https://example.org/edited");
+    const favicons = mockFavicons(null);
+    // Simulate a Places DB failure so #getCachedFavicon hits its catch branch.
+    favicons.mock.getFaviconForPage = () =>
+      Promise.reject(new Error("simulated favicon DB failure"));
+
+    try {
+      await gZenPinnedTabManager.editPinnedUrl(tab);
+
+      Assert.equal(
+        tab._zenPinnedInitialState.entry.url,
+        "https://example.org/edited",
+        "The URL should still be updated when the favicon lookup fails"
+      );
+      ok(
+        !tab._zenPinnedInitialState.image,
+        "The image should be left empty (populated by the next navigation)"
+      );
+    } finally {
+      restorePrompt();
+      favicons.restore();
+      await BrowserTestUtils.removeTab(tab);
+    }
+  }
+);
+
+add_task(async function test_EditPinnedUrl_UpdatesUrlAndFavicon() {
+  const tab = await pinTab("https://example.com/1");
+  const faviconSpec = "data:image/png;base64,iVBORw0KGgo=";
+  const restorePrompt = mockPrompt("https://example.org/edited");
+  const favicons = mockFavicons(faviconSpec);
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    Assert.equal(
+      tab._zenPinnedInitialState.entry.url,
+      "https://example.org/edited",
+      "The pinned URL should be updated to the edited value"
+    );
+    Assert.equal(
+      tab._zenPinnedInitialState.image,
+      faviconSpec,
+      "The stored icon should be the cached favicon for the new URL"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_NoCachedFaviconLeavesImageEmpty() {
+  const tab = await pinTab("https://example.com/1");
+  const restorePrompt = mockPrompt("https://example.org/edited");
+  const favicons = mockFavicons(null); // no cached favicon for the new URL
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    ok(
+      !tab._zenPinnedInitialState.image,
+      "Without a cached favicon the image is left empty, not the default; the " +
+        "next navigation captures the real icon"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_ClearsStaleTitle() {
+  const tab = await pinTab("https://example.com/1");
+  const restorePrompt = mockPrompt("https://example.org/edited");
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    ok(
+      !tab._zenPinnedInitialState.entry.title,
+      "The previous title is cleared so the new page's title is used on load"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_KeepsCustomLabel() {
+  const tab = await pinTab("https://example.com/1");
+  tab.zenStaticLabel = "My Pinned Tab";
+  const restorePrompt = mockPrompt("https://example.org/edited");
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    Assert.equal(
+      tab._zenPinnedInitialState.entry.title,
+      "My Pinned Tab",
+      "An explicit custom label is preserved across a URL edit"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    delete tab.zenStaticLabel;
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_KeepsCustomIcon() {
+  const tab = await pinTab("https://example.com/1");
+  const customIcon = "data:image/svg+xml,custom-icon";
+  tab.zenStaticIcon = customIcon;
+  const restorePrompt = mockPrompt("https://example.org/edited");
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    Assert.equal(
+      tab._zenPinnedInitialState.entry.url,
+      "https://example.org/edited",
+      "The pinned URL should still be updated when a custom icon is set"
+    );
+    Assert.equal(
+      tab._zenPinnedInitialState.image,
+      customIcon,
+      "A user-set custom icon should be preserved, not overridden by a favicon"
+    );
+    Assert.equal(
+      favicons.mock.callCount,
+      0,
+      "Favicon lookup should be skipped when a custom icon is set"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    delete tab.zenStaticIcon;
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_InvalidUrlKeepsState() {
+  const tab = await pinTab("https://example.com/1");
+  const originalUrl = tab._zenPinnedInitialState.entry.url;
+  const restorePrompt = mockPrompt("   "); // whitespace only -> not a valid URL
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    Assert.equal(
+      tab._zenPinnedInitialState.entry.url,
+      originalUrl,
+      "The pinned URL should be unchanged for invalid input"
+    );
+    ok(
+      !tab.hasAttribute("zen-pinned-changed"),
+      "The tab should not be marked as changed for invalid input"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_CancelKeepsState() {
+  const tab = await pinTab("https://example.com/1");
+  const originalUrl = tab._zenPinnedInitialState.entry.url;
+  const restorePrompt = mockPrompt(null); // user cancels the dialog
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    Assert.equal(
+      tab._zenPinnedInitialState.entry.url,
+      originalUrl,
+      "The pinned URL should be unchanged when the dialog is cancelled"
+    );
+  } finally {
+    restorePrompt();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_FixesSchemeTypo() {
+  const tab = await pinTab("https://example.com/1");
+  const restorePrompt = mockPrompt("htps://example.org/typo");
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    Assert.equal(
+      tab._zenPinnedInitialState.entry.url,
+      "https://example.org/typo",
+      "A mistyped scheme (htps://) should be auto-fixed to https://"
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_AddsMissingScheme() {
+  const tab = await pinTab("https://example.com/1");
+  const restorePrompt = mockPrompt("example.org/no-scheme");
+  const favicons = mockFavicons("data:image/png;base64,iVBORw0KGgo=");
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    const stored = tab._zenPinnedInitialState.entry.url;
+    ok(
+      /^https?:\/\//.test(stored),
+      `A scheme should be prepended when omitted (got "${stored}")`
+    );
+    ok(
+      stored.endsWith("example.org/no-scheme"),
+      `Host and path should be preserved (got "${stored}")`
+    );
+  } finally {
+    restorePrompt();
+    favicons.restore();
+    await BrowserTestUtils.removeTab(tab);
+  }
+});
+
+add_task(async function test_EditPinnedUrl_PrefillsWithStoredUrl() {
+  const tab = await pinTab("https://example.com/1");
+  // The stored pinned URL differs from the live browser URL (e.g. it was pinned
+  // as http but the server redirected the tab to https).
+  tab._zenPinnedInitialState = {
+    entry: { url: "http://example.com/pinned" },
+    image: "",
+  };
+
+  let prefilled;
+  const originalPrompt = Services.prompt;
+  Services.prompt = {
+    QueryInterface: ChromeUtils.generateQI([Ci.nsIPromptService]),
+    prompt(win, title, label, result) {
+      prefilled = result.value;
+      return false; // cancel, we only care about the prefilled value
+    },
+  };
+
+  try {
+    await gZenPinnedTabManager.editPinnedUrl(tab);
+
+    Assert.equal(
+      prefilled,
+      "http://example.com/pinned",
+      "The edit dialog should prefill with the stored pinned URL, not the live browser URL"
+    );
+  } finally {
+    Services.prompt = originalPrompt;
+    await BrowserTestUtils.removeTab(tab);
+  }
+});