gh-14044: Finish implementation for space routing (gh-14069)

2026-06-13 15:03:41 +00:00 · 2026-06-08 17:41:00 +02:00
parent 965bb9391d
commit 5db8780f5d
17 changed files with 759 additions and 112 deletions
--- a/prefs/firefox/browser.yaml
+++ b/prefs/firefox/browser.yaml
@@ -94,3 +94,8 @@
 # See gh-12985 for details on the following preferences
 - name: browser.search.widget.new
  value: true
+
+# Disabled from https://searchfox.org/firefox-main/rev/d6bfff43852356ca98af848b4705d37f8d41856f/modules/libpref/init/StaticPrefList.yaml#2008
+# Only enabled for windows, doesn't really fit inside Zen.
+- name: browser.startup.preXulSkeletonUI
+  value: false
--- a/src/browser/components/tabbrowser/content/tabbrowser-js.patch
+++ b/src/browser/components/tabbrowser/content/tabbrowser-js.patch
@@ -1,5 +1,5 @@
 diff --git a/browser/components/tabbrowser/content/tabbrowser.js b/browser/components/tabbrowser/content/tabbrowser.js
-index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a1559780fe22 100644
+index 43fb79a3060e20f671ae6ffc26350c7abf497702..028dfcba9e23a17e4152071dd58eb97a70e59c10 100644
 --- a/browser/components/tabbrowser/content/tabbrowser.js
 +++ b/browser/components/tabbrowser/content/tabbrowser.js
@@ -502,6 +502,7 @@
@@ -79,7 +79,15 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
     set selectedTab(val) {
       if (
         gSharedTabWarning.willShowSharedTabWarning(val) ||
-@@ -659,6 +711,10 @@
+@@ -592,6 +644,7 @@
+       ) {
+         return;
+       }
+      gZenWorkspaces.onBeforeTabSelect(val);
+       // Update the tab
+       this.tabbox.selectedTab = val;
+     }
+@@ -659,6 +712,10 @@
         userContextId = parseInt(tabArgument.getAttribute("usercontextid"), 10);
       }
 
@@ -90,7 +98,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       if (tabArgument && tabArgument.linkedBrowser) {
         remoteType = tabArgument.linkedBrowser.remoteType;
         initialBrowsingContextGroupId =
-@@ -751,6 +807,8 @@
+@@ -751,6 +808,8 @@
       this.tabpanels.appendChild(panel);
 
       let tab = this.tabs[0];
@@ -99,7 +107,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       tab.linkedPanel = uniqueId;
       this._selectedTab = tab;
       this._selectedBrowser = browser;
-@@ -1121,13 +1179,18 @@
+@@ -1121,13 +1180,18 @@
       }
 
       this.showTab(aTab);
@@ -119,7 +127,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       aTab.setAttribute("pinned", "true");
       this._updateTabBarForPinnedTabs();
-@@ -1140,11 +1203,19 @@
+@@ -1140,11 +1204,19 @@
       }
 
       this.#handleTabMove(aTab, () => {
@@ -140,7 +148,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       });
 
       aTab.style.marginInlineStart = "";
-@@ -1321,6 +1392,9 @@
+@@ -1321,6 +1393,9 @@
 
       let LOCAL_PROTOCOLS = ["chrome:", "about:", "resource:", "data:"];
 
@@ -150,7 +158,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       if (
         aIconURL &&
         !LOCAL_PROTOCOLS.some(protocol => aIconURL.startsWith(protocol))
-@@ -1330,6 +1404,9 @@
+@@ -1330,6 +1405,9 @@
         );
         return;
       }
@@ -160,7 +168,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       let browser = this.getBrowserForTab(aTab);
       browser.mIconURL = aIconURL;
-@@ -1652,7 +1729,6 @@
+@@ -1652,7 +1730,6 @@
 
       // Preview mode should not reset the owner
       if (!this._previewMode && !oldTab.selected) {
@@ -168,7 +176,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       }
 
       let lastRelatedTab = this._lastRelatedTabMap.get(oldTab);
-@@ -1743,6 +1819,7 @@
+@@ -1743,6 +1820,7 @@
       if (!this._previewMode) {
         newTab.recordTimeFromUnloadToReload();
         newTab.updateLastAccessed();
@@ -176,7 +184,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         oldTab.updateLastAccessed();
         // if this is the foreground window, update the last-seen timestamps.
         if (this.ownerGlobal == BrowserWindowTracker.getTopWindow()) {
-@@ -1957,6 +2034,9 @@
+@@ -1957,6 +2035,9 @@
       }
 
       let activeEl = document.activeElement;
@@ -186,7 +194,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       // If focus is on the old tab, move it to the new tab.
       if (activeEl == oldTab) {
         newTab.focus();
-@@ -1995,7 +2075,7 @@
+@@ -1995,7 +2076,7 @@
       // Focus the location bar if it was previously focused for that tab.
       // In full screen mode, only bother making the location bar visible
       // if the tab is a blank one.
@@ -195,7 +203,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         let selectURL = () => {
           if (this._asyncTabSwitching) {
             // Set _awaitingSetURI flag to suppress popup notification
-@@ -2283,7 +2363,12 @@
+@@ -2283,7 +2364,12 @@
       return this._setTabLabel(aTab, aLabel);
     }
 
@@ -209,7 +217,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       if (!aLabel || (isURL && /^about:reader\?url=/.test(aLabel))) {
         return false;
       }
-@@ -2408,7 +2493,7 @@
+@@ -2408,7 +2494,7 @@
         newIndex = this.selectedTab._tPos + 1;
       }
 
@@ -218,7 +226,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         if (this.isTabGroupLabel(targetTab)) {
           throw new Error(
             "Replacing a tab group label with a tab is not supported"
-@@ -2685,6 +2770,7 @@
+@@ -2685,6 +2771,7 @@
       uriIsAboutBlank,
       userContextId,
       skipLoad,
@@ -226,7 +234,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
     } = {}) {
       let b = document.createXULElement("browser");
       // Use the JSM global to create the permanentKey, so that if the
-@@ -2758,8 +2844,7 @@
+@@ -2758,8 +2845,7 @@
         // we use a different attribute name for this?
         b.setAttribute("name", name);
       }
@@ -236,7 +244,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         b.setAttribute("transparent", "true");
       }
 
-@@ -2929,7 +3014,7 @@
+@@ -2929,7 +3015,7 @@
 
       let panel = this.getPanel(browser);
       let uniqueId = this._generateUniquePanelID();
@@ -245,7 +253,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       aTab.linkedPanel = uniqueId;
 
       // Inject the <browser> into the DOM if necessary.
-@@ -2989,8 +3074,8 @@
+@@ -2989,8 +3075,8 @@
       // If we transitioned from one browser to two browsers, we need to set
       // hasSiblings=false on both the existing browser and the new browser.
       if (this.tabs.length == 2) {
@@ -256,7 +264,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       } else {
         aTab.linkedBrowser.browsingContext.hasSiblings = this.tabs.length > 1;
       }
-@@ -3175,7 +3260,6 @@
+@@ -3175,7 +3261,6 @@
             this.selectedTab = this.addTrustedTab(BROWSER_NEW_TAB_URL, {
               tabIndex: tab._tPos + 1,
               userContextId: tab.userContextId,
@@ -264,7 +272,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
               focusUrlBar: true,
             });
             resolve(this.selectedBrowser);
-@@ -3285,6 +3369,10 @@
+@@ -3285,6 +3370,10 @@
         schemelessInput,
         hasValidUserGestureActivation = false,
         textDirectiveUserActivation = false,
@@ -275,7 +283,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       } = {}
     ) {
       // all callers of addTab that pass a params object need to pass
-@@ -3295,10 +3383,25 @@
+@@ -3295,10 +3384,25 @@
         );
       }
 
@@ -301,7 +309,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       // If we're opening a foreground tab, set the owner by default.
       ownerTab ??= inBackground ? null : this.selectedTab;
 
-@@ -3306,6 +3409,7 @@
+@@ -3306,6 +3410,7 @@
       if (this.selectedTab.owner) {
         this.selectedTab.owner = null;
       }
@@ -309,7 +317,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       // Find the tab that opened this one, if any. This is used for
       // determining positioning, and inherited attributes such as the
-@@ -3358,6 +3462,22 @@
+@@ -3358,6 +3463,22 @@
           noInitialLabel,
           skipBackgroundNotify,
         });
@@ -332,7 +340,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         if (insertTab) {
           // Insert the tab into the tab container in the correct position.
           this.#insertTabAtIndex(t, {
-@@ -3366,6 +3486,7 @@
+@@ -3366,6 +3487,7 @@
             ownerTab,
             openerTab,
             pinned,
@@ -340,7 +348,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
             bulkOrderedOpen,
             tabGroup: tabGroup ?? openerTab?.group,
           });
-@@ -3384,6 +3505,7 @@
+@@ -3384,6 +3506,7 @@
           openWindowInfo,
           skipLoad,
           triggeringRemoteType,
@@ -348,7 +356,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         }));
 
         if (focusUrlBar) {
-@@ -3508,6 +3630,12 @@
+@@ -3508,6 +3631,12 @@
         }
       }
 
@@ -361,7 +369,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       // Additionally send pinned tab events
       if (pinned) {
         this.#notifyPinnedStatus(t);
-@@ -3518,6 +3646,9 @@
+@@ -3518,6 +3647,9 @@
       if (!inBackground) {
         this.selectedTab = t;
       }
@@ -371,7 +379,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       return t;
     }
 
-@@ -3750,6 +3881,7 @@
+@@ -3750,6 +3882,7 @@
         isAdoptingGroup = false,
         isUserTriggered = false,
         telemetryUserCreateSource = "unknown",
@@ -379,7 +387,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       } = {}
     ) {
       if (
-@@ -3760,9 +3892,6 @@
+@@ -3760,9 +3893,6 @@
             !this.isSplitViewWrapper(tabOrSplitView)
         )
       ) {
@@ -389,7 +397,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       }
 
       if (!color) {
-@@ -3783,9 +3912,14 @@
+@@ -3783,9 +3913,14 @@
         label,
         isAdoptingGroup
       );
@@ -406,7 +414,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       );
       group.addTabs(tabsAndSplitViews);
 
-@@ -3906,7 +4040,7 @@
+@@ -3906,7 +4041,7 @@
       }
 
       this.#handleTabMove(tab, () =>
@@ -415,7 +423,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       );
     }
 
-@@ -3990,6 +4124,7 @@
+@@ -3990,6 +4125,7 @@
         color: group.color,
         insertBefore: newTabs[0],
         isAdoptingGroup: true,
@@ -423,7 +431,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       });
     }
 
-@@ -4200,6 +4335,7 @@
+@@ -4200,6 +4336,7 @@
         openWindowInfo,
         skipLoad,
         triggeringRemoteType,
@@ -431,7 +439,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       }
     ) {
       // If we don't have a preferred remote type (or it is `NOT_REMOTE`), and
-@@ -4269,6 +4405,7 @@
+@@ -4269,6 +4406,7 @@
           openWindowInfo,
           name,
           skipLoad,
@@ -439,7 +447,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         });
       }
 
-@@ -4482,9 +4619,9 @@
+@@ -4482,9 +4620,9 @@
         }
 
         // Add a new tab if needed.
@@ -451,7 +459,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
           let url = "about:blank";
           if (tabData.entries?.length) {
-@@ -4521,8 +4658,10 @@
+@@ -4521,8 +4659,10 @@
             insertTab: false,
             skipLoad: true,
             preferredRemoteType,
@@ -463,7 +471,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
           if (select) {
             tabToSelect = tab;
           }
-@@ -4544,7 +4683,8 @@
+@@ -4544,7 +4684,8 @@
           this.pinTab(tab);
           // Then ensure all the tab open/pinning information is sent.
           this._fireTabOpen(tab, {});
@@ -473,7 +481,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
           let { groupId } = tabData;
           const tabGroup = tabGroupWorkingData.get(groupId);
           // if a tab refers to a tab group we don't know, skip any group
-@@ -4564,7 +4704,10 @@
+@@ -4564,7 +4705,10 @@
                 tabGroup.stateData.id,
                 tabGroup.stateData.color,
                 tabGroup.stateData.collapsed,
@@ -485,7 +493,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
               );
               tabsFragment.appendChild(tabGroup.node);
             }
-@@ -4619,9 +4762,21 @@
+@@ -4619,9 +4763,21 @@
       // to remove the old selected tab.
       if (tabToSelect) {
         let leftoverTab = this.selectedTab;
@@ -507,7 +515,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       if (tabs.length > 1 || !tabs[0].selected) {
         this._updateTabsAfterInsert();
-@@ -4812,11 +4967,14 @@
+@@ -4812,11 +4968,14 @@
       if (ownerTab) {
         tab.owner = ownerTab;
       }
@@ -523,7 +531,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         if (
           !bulkOrderedOpen &&
           ((openerTab &&
-@@ -4828,7 +4986,7 @@
+@@ -4828,7 +4987,7 @@
           let lastRelatedTab =
             openerTab && this._lastRelatedTabMap.get(openerTab);
           let previousTab = lastRelatedTab || openerTab || this.selectedTab;
@@ -532,7 +540,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
             tabGroup = previousTab.group;
           }
           if (
-@@ -4844,7 +5002,7 @@
+@@ -4844,7 +5003,7 @@
                 previousTab.splitview
               ) + 1;
           } else if (previousTab.visible) {
@@ -541,7 +549,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
           } else if (previousTab == FirefoxViewHandler.tab) {
             elementIndex = 0;
           }
-@@ -4872,14 +5030,14 @@
+@@ -4872,14 +5031,14 @@
       }
       // Ensure index is within bounds.
       if (tab.pinned) {
@@ -560,7 +568,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       if (pinned && !itemAfter?.pinned) {
         itemAfter = null;
-@@ -4896,7 +5054,7 @@
+@@ -4896,7 +5055,7 @@
 
       this.tabContainer._invalidateCachedTabs();
 
@@ -569,7 +577,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         if (
           (this.isTab(itemAfter) && itemAfter.group == tabGroup) ||
           this.isSplitViewWrapper(itemAfter)
-@@ -4927,7 +5085,11 @@
+@@ -4927,7 +5086,11 @@
         const tabContainer = pinned
           ? this.tabContainer.pinnedTabsContainer
           : this.tabContainer;
@@ -581,7 +589,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       }
 
       if (tab.group?.collapsed) {
-@@ -4942,6 +5104,7 @@
+@@ -4942,6 +5105,7 @@
       if (pinned) {
         this._updateTabBarForPinnedTabs();
       }
@@ -589,7 +597,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       TabBarVisibility.update();
     }
-@@ -5490,6 +5653,7 @@
+@@ -5490,6 +5654,7 @@
         telemetrySource,
       } = {}
     ) {
@@ -597,7 +605,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       // When 'closeWindowWithLastTab' pref is enabled, closing all tabs
       // can be considered equivalent to closing the window.
       if (
-@@ -5579,6 +5743,7 @@
+@@ -5579,6 +5744,7 @@
         if (lastToClose) {
           this.removeTab(lastToClose, aParams);
         }
@@ -605,7 +613,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       } catch (e) {
         console.error(e);
       }
-@@ -5624,6 +5789,14 @@
+@@ -5624,6 +5790,14 @@
         return;
       }
 
@@ -620,7 +628,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       let isVisibleTab = aTab.visible;
       // We have to sample the tab width now, since _beginRemoveTab might
       // end up modifying the DOM in such a way that aTab gets a new
-@@ -5631,6 +5804,9 @@
+@@ -5631,6 +5805,9 @@
       // state).
       let tabWidth = window.windowUtils.getBoundsWithoutFlushing(aTab).width;
       let isLastTab = this.#isLastTabInWindow(aTab);
@@ -630,7 +638,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       if (
         !this._beginRemoveTab(aTab, {
           closeWindowFastpath: true,
-@@ -5642,13 +5818,14 @@
+@@ -5642,13 +5819,14 @@
           telemetrySource,
         })
       ) {
@@ -646,7 +654,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       let lockTabSizing =
         !this.tabContainer.verticalMode &&
         !aTab.pinned &&
-@@ -5679,7 +5856,13 @@
+@@ -5679,7 +5857,13 @@
         // We're not animating, so we can cancel the animation stopwatch.
         Glean.browserTabclose.timeAnim.cancel(aTab._closeTimeAnimTimerId);
         aTab._closeTimeAnimTimerId = null;
@@ -661,7 +669,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         return;
       }
 
-@@ -5813,7 +5996,7 @@
+@@ -5813,7 +5997,7 @@
           closeWindowWithLastTab != null
             ? closeWindowWithLastTab
             : !window.toolbar.visible ||
@@ -670,7 +678,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
         if (closeWindow) {
           // We've already called beforeunload on all the relevant tabs if we get here,
-@@ -5837,6 +6020,7 @@
+@@ -5837,6 +6021,7 @@
 
         newTab = true;
       }
@@ -678,7 +686,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       aTab._endRemoveArgs = [closeWindow, newTab];
 
       // swapBrowsersAndCloseOther will take care of closing the window without animation.
-@@ -5877,13 +6061,7 @@
+@@ -5877,13 +6062,7 @@
       aTab._mouseleave();
 
       if (newTab) {
@@ -693,7 +701,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       } else {
         TabBarVisibility.update();
       }
-@@ -6016,6 +6194,7 @@
+@@ -6016,6 +6195,7 @@
         this.tabs[i]._tPos = i;
       }
 
@@ -701,7 +709,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       if (!this._windowIsClosing) {
         // update tab close buttons state
         this.tabContainer._updateCloseButtons();
-@@ -6201,6 +6380,7 @@
+@@ -6201,6 +6381,7 @@
         memory_after: await getTotalMemoryUsage(),
         time_to_unload_in_ms: timeElapsed,
       });
@@ -709,7 +717,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
     }
 
     /**
-@@ -6246,6 +6426,7 @@
+@@ -6246,6 +6427,7 @@
       }
 
       let excludeTabs = new Set(aExcludeTabs);
@@ -717,7 +725,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       // If this tab has a successor, it should be selectable, since
       // hiding or closing a tab removes that tab as a successor.
-@@ -6258,15 +6439,22 @@
+@@ -6258,15 +6440,22 @@
         !excludeTabs.has(aTab.owner) &&
         Services.prefs.getBoolPref("browser.tabs.selectOwnerOnClose")
       ) {
@@ -742,7 +750,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       let tab = this.tabContainer.findNextTab(aTab, {
         direction: 1,
         filter: _tab => remainingTabs.includes(_tab),
-@@ -6280,7 +6468,7 @@
+@@ -6280,7 +6469,7 @@
       }
 
       if (tab) {
@@ -751,7 +759,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       }
 
       // If no qualifying visible tab was found, see if there is a tab in
-@@ -6301,7 +6489,7 @@
+@@ -6301,7 +6490,7 @@
         });
       }
 
@@ -760,7 +768,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
     }
 
     _blurTab(aTab) {
-@@ -6312,7 +6500,7 @@
+@@ -6312,7 +6501,7 @@
      * @returns {boolean}
      *   False if swapping isn't permitted, true otherwise.
      */
@@ -769,7 +777,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       // Do not allow transfering a private tab to a non-private window
       // and vice versa.
       if (
-@@ -6366,6 +6554,7 @@
+@@ -6366,6 +6555,7 @@
       // fire the beforeunload event in the process.  Close the other
       // window if this was its last tab.
       if (
@@ -777,7 +785,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         !remoteBrowser._beginRemoveTab(aOtherTab, {
           adoptedByTab: aOurTab,
           closeWindowWithLastTab: true,
-@@ -6377,7 +6566,7 @@
+@@ -6377,7 +6567,7 @@
       // If this is the last tab of the window, hide the window
       // immediately without animation before the docshell swap, to avoid
       // about:blank being painted.
@@ -786,7 +794,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       if (closeWindow) {
         let win = aOtherTab.ownerGlobal;
         win.windowUtils.suppressAnimation(true);
-@@ -6511,11 +6700,13 @@
+@@ -6511,11 +6701,13 @@
       }
 
       // Finish tearing down the tab that's going away.
@@ -800,7 +808,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       this.setTabTitle(aOurTab);
 
-@@ -6717,10 +6908,10 @@
+@@ -6717,10 +6909,10 @@
       SessionStore.deleteCustomTabValue(aTab, "hiddenBy");
     }
 
@@ -813,7 +821,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         aTab.selected ||
         aTab.closing ||
         // Tabs that are sharing the screen, microphone or camera cannot be hidden.
-@@ -6780,7 +6971,8 @@
+@@ -6780,7 +6972,8 @@
      * @param {object} [aOptions={}]
      *   Key-value pairs that will be serialized into the features string.
      */
@@ -823,7 +831,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       if (this.tabs.length == 1) {
         return null;
       }
-@@ -6797,7 +6989,7 @@
+@@ -6797,7 +6990,7 @@
       // tell a new window to take the "dropped" tab
       let args = Cc["@mozilla.org/array;1"].createInstance(Ci.nsIMutableArray);
       args.appendElement(aTab.splitview ?? aTab);
@@ -832,7 +840,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         private: PrivateBrowsingUtils.isWindowPrivate(window),
         features: Object.entries(aOptions)
           .map(([key, value]) => `${key}=${value}`)
-@@ -6805,6 +6997,8 @@
+@@ -6805,6 +6998,8 @@
         openerWindow: window,
         args,
       });
@@ -841,7 +849,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
     }
 
     /**
-@@ -6917,7 +7111,7 @@
+@@ -6917,7 +7112,7 @@
      *   `true` if element is a `<tab-group>`
      */
     isTabGroup(element) {
@@ -850,7 +858,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
     }
 
     /**
-@@ -7002,8 +7196,8 @@
+@@ -7002,8 +7197,8 @@
       }
 
       // Don't allow mixing pinned and unpinned tabs.
@@ -861,7 +869,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       } else {
         tabIndex = Math.max(tabIndex, this.pinnedTabCount);
       }
-@@ -7049,8 +7243,8 @@
+@@ -7049,8 +7244,8 @@
       this.#handleTabMove(
         element,
         () => {
@@ -872,7 +880,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
             neighbor = neighbor.group;
           }
           if (neighbor?.splitview) {
-@@ -7061,6 +7255,12 @@
+@@ -7061,6 +7256,12 @@
               return;
             }
           }
@@ -885,7 +893,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
           if (movingForwards && neighbor) {
             neighbor.after(element);
-@@ -7119,23 +7319,31 @@
+@@ -7119,23 +7320,31 @@
     #moveTabNextTo(element, targetElement, moveBefore = false, metricsContext) {
       if (this.isTabGroupLabel(targetElement)) {
         targetElement = targetElement.group;
@@ -923,7 +931,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       } else if (!element.pinned && targetElement && targetElement.pinned) {
         // If the caller asks to move an unpinned element next to a pinned
         // tab, move the unpinned element to be the first unpinned element
-@@ -7148,12 +7356,35 @@
+@@ -7148,12 +7357,35 @@
         //    move the tab group right before the first unpinned tab.
         // 4. Moving a tab group and the first unpinned tab is grouped:
         //    move the tab group right before the first unpinned tab's tab group.
@@ -960,7 +968,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       // We want to include the splitview wrapper if it's the targetElement, but
       // not in the case where we want to reverse tabs within the same splitview.
-@@ -7162,6 +7393,7 @@
+@@ -7162,6 +7394,7 @@
       }
 
       let getContainer = () =>
@@ -968,7 +976,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         element.pinned
           ? this.tabContainer.pinnedTabsContainer
           : this.tabContainer;
-@@ -7170,11 +7402,15 @@
+@@ -7170,11 +7403,15 @@
         element,
         () => {
           if (moveBefore) {
@@ -985,7 +993,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
           }
         },
         metricsContext
-@@ -7248,11 +7484,15 @@
+@@ -7248,11 +7485,15 @@
      * @param {TabMetricsContext} [metricsContext]
      */
     moveTabToExistingGroup(aTab, aGroup, metricsContext) {
@@ -1004,7 +1012,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       }
       if (aTab.group && aTab.group.id === aGroup.id) {
         return;
-@@ -7324,6 +7564,7 @@
+@@ -7324,6 +7565,7 @@
 
       let state = {
         tabIndex: tab._tPos,
@@ -1012,7 +1020,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       };
       if (tab.visible) {
         state.elementIndex = tab.elementIndex;
-@@ -7355,7 +7596,7 @@
+@@ -7355,7 +7597,7 @@
       let changedSplitView =
         previousTabState.splitViewId != currentTabState.splitViewId;
 
@@ -1021,7 +1029,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         tab.dispatchEvent(
           new CustomEvent("TabMove", {
             bubbles: true,
-@@ -7402,6 +7643,10 @@
+@@ -7402,6 +7644,10 @@
 
       moveActionCallback();
 
@@ -1032,7 +1040,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       // Clear tabs cache after moving nodes because the order of tabs may have
       // changed.
       this.tabContainer._invalidateCachedTabs();
-@@ -7452,7 +7697,22 @@
+@@ -7452,7 +7698,22 @@
      * @returns {object}
      *    The new tab in the current window, null if the tab couldn't be adopted.
      */
@@ -1056,7 +1064,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       // Swap the dropped tab with a new one we create and then close
       // it in the other window (making it seem to have moved between
       // windows). We also ensure that the tab we create to swap into has
-@@ -7495,6 +7755,8 @@
+@@ -7495,6 +7756,8 @@
       }
       params.skipLoad = true;
       let newTab = this.addWebTab("about:blank", params);
@@ -1065,7 +1073,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
       aTab.container.tabDragAndDrop.finishAnimateTabMove();
 
-@@ -8205,7 +8467,7 @@
+@@ -8205,7 +8468,7 @@
         // preventDefault(). It will still raise the window if appropriate.
         return;
       }
@@ -1074,7 +1082,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       window.focus();
       aEvent.preventDefault();
     }
-@@ -8222,7 +8484,6 @@
+@@ -8222,7 +8485,6 @@
 
     on_TabGroupCollapse(aEvent) {
       aEvent.target.tabs.forEach(tab => {
@@ -1082,7 +1090,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
       });
     }
 
-@@ -8556,7 +8817,9 @@
+@@ -8556,7 +8818,9 @@
 
         let filter = this._tabFilters.get(tab);
         if (filter) {
@@ -1092,7 +1100,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
 
           let listener = this._tabListeners.get(tab);
           if (listener) {
-@@ -9359,6 +9622,7 @@
+@@ -9359,6 +9623,7 @@
             aWebProgress.isTopLevel
           ) {
             this.mTab.setAttribute("busy", "true");
@@ -1100,7 +1108,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
             gBrowser._tabAttrModified(this.mTab, ["busy"]);
             this.mTab._notselectedsinceload = !this.mTab.selected;
           }
-@@ -9439,6 +9703,7 @@
+@@ -9439,6 +9704,7 @@
         // known defaults. Note we use the original URL since about:newtab
         // redirects to a prerendered page.
         const shouldRemoveFavicon =
@@ -1108,7 +1116,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
           !this.mBrowser.mIconURL &&
           !ignoreBlank &&
           !(originalLocation.spec in FAVICON_DEFAULTS);
-@@ -9613,13 +9878,6 @@
+@@ -9613,13 +9879,6 @@
             this.mBrowser.originalURI = aRequest.originalURI;
           }
 
@@ -1122,7 +1130,7 @@ index 43fb79a3060e20f671ae6ffc26350c7abf497702..2da16e06541438ece4a3ae3a1663a155
         }
 
         let userContextId = this.mBrowser.getAttribute("usercontextid") || 0;
-@@ -10507,7 +10765,8 @@ var TabContextMenu = {
+@@ -10507,7 +10766,8 @@ var TabContextMenu = {
     );
     contextUnpinSelectedTabs.hidden =
       !this.contextTab.pinned || !this.multiselected;
--- a/src/zen/common/modules/ZenStartup.mjs
+++ b/src/zen/common/modules/ZenStartup.mjs
@@ -147,7 +147,7 @@ class ZenStartup {
  }

  #initUIComponents() {
-    const kUIComponents = ["ZenProgressBar"];
+    const kUIComponents = ["ZenProgressBar", "ZenSpaceRoutingNavigation"];
    for (let component of kUIComponents) {
      const module = ChromeUtils.importESModule(
        "resource:///modules/zen/ui/" + component + ".sys.mjs"
--- a/src/zen/common/moz.build
+++ b/src/zen/common/moz.build
@@ -10,5 +10,6 @@ EXTRA_JS_MODULES += [

 EXTRA_JS_MODULES.zen.ui += [
  "sys/ui/ZenProgressBar.sys.mjs",
+  "sys/ui/ZenSpaceRoutingNavigation.sys.mjs",
  "sys/ui/ZenUIComponent.sys.mjs",
 ]
--- a/src/zen/common/sys/ui/ZenSpaceRoutingNavigation.sys.mjs
+++ b/src/zen/common/sys/ui/ZenSpaceRoutingNavigation.sys.mjs
@@ -0,0 +1,122 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import { ZenUIComponent } from "resource:///modules/zen/ui/ZenUIComponent.sys.mjs";
+
+/**
+ * Per-window listener that re-routes in-place navigations for Space Routing.
+ *
+ * When any top-level navigation (link click, address bar, JS redirect, form
+ * submit, ...) targets a URL whose rule points at a *different* space than the
+ * one the tab currently lives in, the load is cancelled and re-opened in a new
+ * tab. The new tab flows through tabbrowser's addTab() routing, which moves it
+ * into the matching space.
+ */
+export class ZenSpaceRoutingNavigation extends ZenUIComponent {
+  init() {
+    this.listenBrowserTabsProgress();
+  }
+
+  /**
+   * @param {MozBrowser} aBrowser - The browser the state change happened in
+   * @param {nsIWebProgress} aWebProgress - The web progress
+   * @param {nsIRequest} aRequest - The request driving the state change
+   * @param {number} aStateFlags - The nsIWebProgressListener state flags
+   */
+  onStateChange(aBrowser, aWebProgress, aRequest, aStateFlags) {
+    const wpl = Ci.nsIWebProgressListener;
+    if (
+      !aWebProgress?.isTopLevel ||
+      !(aStateFlags & wpl.STATE_START) ||
+      !(aStateFlags & wpl.STATE_IS_DOCUMENT)
+    ) {
+      return;
+    }
+
+    // The tab we spawn for a route must be allowed to load once without being
+    // redirected again, regardless of when its workspace attribute lands.
+    if (aBrowser._zenSkipNavRouteOnce) {
+      aBrowser._zenSkipNavRouteOnce = false;
+      return;
+    }
+
+    let uri;
+    try {
+      uri = aRequest.QueryInterface(Ci.nsIChannel).URI;
+    } catch (e) {
+      return;
+    }
+    if (!uri || !(uri.schemeIs("http") || uri.schemeIs("https"))) {
+      return;
+    }
+
+    // Don't disturb a tab that is merely (re)loading the page it already shows:
+    // a reload, a session restore, or a tab that was already sitting on this URL
+    // before the rule was set. At STATE_START the browser's currentURI still
+    // points at the existing document, so an equal target means this isn't a
+    // new navigation worth routing.
+    let currentURI = null;
+    try {
+      currentURI = aBrowser.currentURI;
+    } catch (e) {
+      currentURI = null;
+    }
+    if (currentURI?.equals(uri)) {
+      return;
+    }
+
+    const win = this.window;
+    const gBrowser = win.gBrowser;
+    const tab = gBrowser.getTabForBrowser(aBrowser);
+    if (
+      !tab ||
+      tab.pinned ||
+      tab.hasAttribute("zen-empty-tab") ||
+      tab.hasAttribute("zen-glance-tab")
+    ) {
+      return;
+    }
+
+    const currentWorkspaceId = tab.getAttribute("zen-workspace-id");
+    if (
+      !win.gZenSpaceRoutingManager.shouldRedirectNavigation(
+        uri.spec,
+        currentWorkspaceId,
+        win
+      )
+    ) {
+      return;
+    }
+
+    // Under Fission the parent-side aRequest is a RemoteWebProgress stand-in
+    // whose cancel()/loadInfo throw NS_ERROR_NOT_IMPLEMENTED (the real channel
+    // lives in the content process). Stop the in-place load through the browser,
+    // which proxies the request to the content process.
+    try {
+      aBrowser.stop();
+    } catch (e) {
+      return;
+    }
+
+    const urlToOpen = uri.spec;
+
+    // loadInfo isn't reachable on the remote request, so use the navigating
+    // page as the triggering principal (correct for link clicks), with a null
+    // principal as the safe last resort.
+    const principal =
+      aBrowser.contentPrincipal ||
+      Services.scriptSecurityManager.createNullPrincipal({});
+
+    // Defer so we don't mutate the tab strip from inside a progress notification.
+    win.setTimeout(() => {
+      const newTab = gBrowser.addTab(urlToOpen, {
+        triggeringPrincipal: principal,
+        ownerTab: tab.isConnected ? tab : null,
+      });
+      if (newTab?.linkedBrowser) {
+        newTab.linkedBrowser._zenSkipNavRouteOnce = true;
+      }
+    }, 0);
+  }
+}
--- a/src/zen/space-routing/ZenSpaceRoutingManager.sys.mjs
+++ b/src/zen/space-routing/ZenSpaceRoutingManager.sys.mjs
@@ -82,6 +82,40 @@ class nsZenSpaceRoutingManager {
    this.#routeToWorkspace(targetRoute, newTab, win);
  }

+  /**
+   * Decides whether an in-place top-level navigation should be pulled out of
+   * the current tab and re-opened in a new tab, so that addTab()'s routing can
+   * move it into the space its rule points at.
+   *
+   * Only navigations whose rule targets a *different* space than the one the
+   * navigating tab already lives in are redirected. Staying put when the tab is
+   * already in the destination space keeps normal browsing in place and also
+   * prevents the freshly routed tab from being redirected again (infinite loop).
+   *
+   * @param {string} uriString - The destination URI
+   * @param {string|null} currentWorkspaceId - The zen-workspace-id of the navigating tab
+   * @param {Window} win - The owning browser window
+   * @returns {boolean} True when the navigation should open in a new routed tab
+   */
+  shouldRedirectNavigation(uriString, currentWorkspaceId, win) {
+    if (!win?.gZenWorkspaces?.workspaceEnabled) {
+      return false;
+    }
+
+    const targetRoute = this.routeUri(uriString, { fromExternal: false });
+
+    // No specific destination, or the tab is already where the rule points.
+    if (
+      targetRoute === "most-recent-space" ||
+      targetRoute === currentWorkspaceId
+    ) {
+      return false;
+    }
+
+    // Only redirect when the destination space actually exists.
+    return !!win.gZenWorkspaces.getWorkspaceFromId(targetRoute);
+  }
+
  /**
   * Checks if the tab should be processed or not
   *
--- a/src/zen/spaces/ZenGradientGenerator.mjs
+++ b/src/zen/spaces/ZenGradientGenerator.mjs
@@ -1494,12 +1494,9 @@ export class nsZenThemePicker extends nsZenMultiWindowFeature {
    return color;
  }

-  getToolbarColor(isDarkMode = false, accentColor = null) {
+  getToolbarColor(isDarkMode = false) {
    const opacity = 0.8;
    let baseColor = isDarkMode ? [255, 255, 255, opacity] : [0, 0, 0, opacity]; // Default toolbar
-    if (accentColor) {
-      return this.blendColors(baseColor.slice(0, 3), accentColor, 75).concat(1);
-    }
    return baseColor;
  }

@@ -1765,7 +1762,7 @@ export class nsZenThemePicker extends nsZenMultiWindowFeature {
        docElement.style.setProperty("--zen-primary-color", primaryColor);

        // Set `--toolbox-textcolor` to have a contrast with the primary color
-        let textColor = this.getToolbarColor(isDarkMode, dominantColor);
+        let textColor = this.getToolbarColor(isDarkMode);
        docElement.style.setProperty(
          "--toolbox-textcolor",
          `rgba(${textColor[0]}, ${textColor[1]}, ${textColor[2]}, ${textColor[3]})`
@@ -2011,7 +2008,7 @@ export class nsZenThemePicker extends nsZenMultiWindowFeature {
      grain: theme.texture ?? 0,
      isDarkMode,
      isExplicitMode,
-      toolbarColor: this.getToolbarColor(isDarkMode, dominantColor),
+      toolbarColor: this.getToolbarColor(isDarkMode),
      primaryColor: this.getAccentColorForUI(dominantColor, isDarkMode),
    };
    this.currentOpacity = previousOpacity;
--- a/src/zen/spaces/ZenSpaceManager.mjs
+++ b/src/zen/spaces/ZenSpaceManager.mjs
@@ -1498,7 +1498,6 @@ class nsZenWorkspaces {
        continue;
      }

-      tab.owner = null;
      if (container) {
        if (tab.group?.hasAttribute("split-view-group")) {
          gBrowser.zenHandleTabMove(tab.group, () => {
@@ -2282,6 +2281,18 @@ class nsZenWorkspaces {
    );
  }

+  onBeforeTabSelect(aTab) {
+    const tabSpace = aTab?.getAttribute("zen-workspace-id");
+    if (
+      tabSpace &&
+      tabSpace !== this.activeWorkspace &&
+      !aTab.hasAttribute("zen-empty-tab") &&
+      !aTab.hasAttribute("zen-essential")
+    ) {
+      this.changeWorkspaceWithID(tabSpace);
+    }
+  }
+
  _shouldShowTab(tab, workspaceUuid, containerId, workspaces) {
    const isEssential = tab.getAttribute("zen-essential") === "true";
    const tabWorkspaceId = tab.getAttribute("zen-workspace-id");
--- a/src/zen/spaces/zen-workspaces.css
+++ b/src/zen/spaces/zen-workspaces.css
@@ -321,7 +321,11 @@ zen-workspace {
  position: absolute;
  height: 100%;
  overflow: hidden;
-  color: var(--toolbox-textcolor);
+  color: color-mix(in srgb, var(--toolbox-textcolor) 95%, var(--zen-primary-color));
+
+  --tab-selected-bgcolor: color-mix(in srgb, light-dark(rgba(255, 255, 255, 0.8), rgba(255, 255, 255, 0.18)) 95%, var(--zen-primary-color)) !important;
+  --tab-selected-shadow: 0 0.8px 1.5px 0px light-dark(rgba(0, 0, 0, 0.15), rgba(0, 0, 0, 0.05)) !important;
+  --tab-selected-textcolor: color-mix(in srgb, var(--toolbox-textcolor) 95%, var(--zen-primary-color)) !important;

  @media not (prefers-reduced-motion: reduce) {
    transition: padding-top 0.1s;
--- a/src/zen/tabs/zen-tabs/vertical-tabs.css
+++ b/src/zen/tabs/zen-tabs/vertical-tabs.css
@@ -303,8 +303,6 @@
  border-bottom: 0 solid transparent !important;

  --tab-block-margin: 2px;
-  --tab-selected-bgcolor: light-dark(rgba(255, 255, 255, 0.8), rgba(255, 255, 255, 0.18));
-  --tab-selected-shadow: 0 0.8px 1.5px 0px light-dark(rgba(0, 0, 0, 0.15), rgba(0, 0, 0, 0.05)) !important;
  grid-gap: 0 !important;

  &[overflow]::after,
--- a/src/zen/tests/space_routing/browser.toml
+++ b/src/zen/tests/space_routing/browser.toml
@@ -11,8 +11,12 @@ support-files = [

 ["browser_space_routing_dialog.js"]

+["browser_space_routing_fuzz.js"]
+
 ["browser_space_routing_on_add_tab.js"]

+["browser_space_routing_redirect_navigation.js"]
+
 ["browser_space_routing_route_matching.js"]

 ["browser_space_routing_route_uri.js"]
--- a/src/zen/tests/space_routing/browser_space_routing_dialog.js
+++ b/src/zen/tests/space_routing/browser_space_routing_dialog.js
@@ -199,7 +199,7 @@ add_task(async function test_routes_are_saved_on_close() {
  };

  try {
-    const closed = BrowserTestUtils.domWindowClosed(dlg);
+    const closed = promiseRoutingDialogClosed();
    dlg.close();
    await TestUtils.waitForCondition(
      () => saveCalls > 0,
@@ -241,11 +241,15 @@ add_task(async function test_open_broadcasts_kill_to_other_instances() {

 add_task(async function test_kill_notification_closes_dialog() {
  clearAllRoutes();
-  const dlg = await openRoutingDialog();
+  await openRoutingDialog();

-  const closed = BrowserTestUtils.domWindowClosed(dlg);
+  const closed = promiseRoutingDialogClosed();
  Services.obs.notifyObservers(null, "zen-space-routing-kill");
  await closed;

-  ok(dlg.closed, "A 'zen-space-routing-kill' notification closes the dialog");
+  const container = document.getElementById("window-modal-dialog");
+  ok(
+    !container.open && !container.hasChildNodes(),
+    "A 'zen-space-routing-kill' notification closes the dialog"
+  );
 });
--- a/src/zen/tests/space_routing/browser_space_routing_fuzz.js
+++ b/src/zen/tests/space_routing/browser_space_routing_fuzz.js
@@ -0,0 +1,239 @@
+/* Any copyright is dedicated to the Public Domain.
+   https://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Seeded fuzzing for the pure routing decision functions. The point is not to
+// assert a particular routing outcome but to prove robustness invariants under
+// adversarial input: the functions must never throw, must always return the
+// declared type, and routeUri must only ever return a value it is allowed to.
+//
+// The RNG is seeded so any failure is reproducible: re-run with the logged seed.
+
+const FUZZ_SEED = 0x5eed1234;
+
+// mulberry32 — small, fast, deterministic PRNG.
+function makeRng(seed) {
+  let s = seed >>> 0;
+  return function rng() {
+    s = (s + 0x6d2b79f5) | 0;
+    let t = Math.imul(s ^ (s >>> 15), 1 | s);
+    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
+    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
+  };
+}
+
+const DOMAIN_CHARS = "abcdefghijklmnopqrstuvwxyz0123456789-.";
+const REGEX_CHARS = ".*+?^${}()|[]\\" + DOMAIN_CHARS;
+const TRICKY_CHARS =
+  DOMAIN_CHARS + "%/?#:@!$&'()*+,;= []{}<>\"\\^`|~\tünïçødé日本語🚀";
+const SCHEMES = [
+  "http://",
+  "https://",
+  "ftp://",
+  "file://",
+  "about:",
+  "data:text/plain,",
+  "javascript:",
+  "//",
+  "",
+];
+const MATCH_TYPES = ["contains", "equal-to", "regex", "bogus-type", ""];
+
+function randInt(rng, n) {
+  return Math.floor(rng() * n);
+}
+function pick(rng, arr) {
+  return arr[randInt(rng, arr.length)];
+}
+function randString(rng, maxLen, charset) {
+  const len = randInt(rng, maxLen + 1);
+  let out = "";
+  for (let i = 0; i < len; i++) {
+    out += charset[randInt(rng, charset.length)];
+  }
+  return out;
+}
+
+function randomUrl(rng) {
+  const scheme = pick(rng, SCHEMES);
+  const host = randString(rng, 30, DOMAIN_CHARS + "ünïçødé");
+  const port = rng() < 0.2 ? ":" + randInt(rng, 99999) : "";
+  const path = rng() < 0.7 ? "/" + randString(rng, 40, TRICKY_CHARS) : "";
+  return scheme + host + port + path;
+}
+
+function randomReference(rng) {
+  switch (randInt(rng, 5)) {
+    case 0:
+      return "";
+    case 1:
+      return "   ";
+    case 2:
+      return randString(rng, 30, DOMAIN_CHARS);
+    case 3:
+      // Deliberately regex-flavoured to exercise the "regex" match path.
+      return randString(rng, 20, REGEX_CHARS);
+    default:
+      return randString(rng, 50, TRICKY_CHARS);
+  }
+}
+
+function randomRoute(rng, openIn = "most-recent-space") {
+  return {
+    id: "fuzz-" + randInt(rng, 1e9),
+    reference: randomReference(rng),
+    openIn,
+    matchType: pick(rng, MATCH_TYPES),
+  };
+}
+
+add_setup(async function () {
+  clearAllRoutes();
+  registerCleanupFunction(() => clearAllRoutes());
+  info(`Space Routing fuzz seed: 0x${FUZZ_SEED.toString(16)}`);
+});
+
+add_task(async function fuzz_isRouteMatching_never_throws() {
+  const rng = makeRng(FUZZ_SEED);
+  const ITERATIONS = 5000;
+
+  for (let i = 0; i < ITERATIONS; i++) {
+    const url = randomUrl(rng);
+    const route = randomRoute(rng);
+
+    let result;
+    try {
+      result = gZenSpaceRoutingManager.isRouteMatching(url, route);
+    } catch (e) {
+      ok(
+        false,
+        `isRouteMatching threw on url=${JSON.stringify(
+          url
+        )} route=${JSON.stringify(route)}: ${e}`
+      );
+      continue;
+    }
+
+    is(
+      typeof result,
+      "boolean",
+      `isRouteMatching must return a boolean (iter ${i})`
+    );
+
+    // An empty / whitespace reference can never match.
+    if (typeof route.reference !== "string" || route.reference.trim() === "") {
+      ok(!result, "Empty reference never matches");
+    }
+  }
+});
+
+add_task(async function fuzz_routeUri_returns_only_valid_destinations() {
+  const rng = makeRng(FUZZ_SEED ^ 0x1111);
+  clearAllRoutes();
+
+  // Populate the manager with a mix of routes pointing at a few destinations.
+  const destinations = ["most-recent-space", "ws-a", "ws-b", "ws-c"];
+  for (let i = 0; i < 200; i++) {
+    const r = randomRoute(rng, pick(rng, destinations));
+    addRoute({
+      reference: r.reference,
+      openIn: r.openIn,
+      matchType: r.matchType,
+    });
+  }
+
+  const allowed = new Set(
+    gZenSpaceRoutingManager.getAllRoutes().map(r => r.openIn)
+  );
+  allowed.add("most-recent-space");
+  const defaultExternal = gZenSpaceRoutingManager.getDefaultExternalRoute();
+  allowed.add(defaultExternal);
+
+  const ITERATIONS = 4000;
+  for (let i = 0; i < ITERATIONS; i++) {
+    const url = randomUrl(rng);
+    const fromExternal = rng() < 0.5;
+
+    let result;
+    try {
+      result = gZenSpaceRoutingManager.routeUri(url, { fromExternal });
+    } catch (e) {
+      ok(false, `routeUri threw on url=${JSON.stringify(url)}: ${e}`);
+      continue;
+    }
+
+    is(typeof result, "string", `routeUri must return a string (iter ${i})`);
+    ok(
+      allowed.has(result),
+      `routeUri returned an out-of-set destination: ${JSON.stringify(result)}`
+    );
+  }
+
+  clearAllRoutes();
+});
+
+add_task(async function fuzz_shouldRedirectNavigation_invariants() {
+  const rng = makeRng(FUZZ_SEED ^ 0x2222);
+  clearAllRoutes();
+
+  const workspaces = [
+    { uuid: "ws-a", containerTabId: 1 },
+    { uuid: "ws-b", containerTabId: 2 },
+  ];
+  const win = makeFakeWindow({ workspaces });
+
+  for (let i = 0; i < 120; i++) {
+    const r = randomRoute(
+      rng,
+      pick(rng, ["ws-a", "ws-b", "most-recent-space"])
+    );
+    addRoute({
+      reference: r.reference,
+      openIn: r.openIn,
+      matchType: r.matchType,
+    });
+  }
+
+  const ITERATIONS = 4000;
+  const currentChoices = ["ws-a", "ws-b", "ws-other", "", null];
+
+  for (let i = 0; i < ITERATIONS; i++) {
+    const url = randomUrl(rng);
+    const currentWorkspaceId = pick(rng, currentChoices);
+
+    let result;
+    try {
+      result = gZenSpaceRoutingManager.shouldRedirectNavigation(
+        url,
+        currentWorkspaceId,
+        win
+      );
+    } catch (e) {
+      ok(
+        false,
+        `shouldRedirectNavigation threw on url=${JSON.stringify(url)}: ${e}`
+      );
+      continue;
+    }
+
+    is(typeof result, "boolean", "shouldRedirectNavigation returns a boolean");
+
+    if (result) {
+      // If we decided to redirect, the target must be a real, *different* space.
+      const target = gZenSpaceRoutingManager.routeUri(url, {
+        fromExternal: false,
+      });
+      ok(
+        target !== "most-recent-space" && target !== currentWorkspaceId,
+        `Redirect target must differ from current space (url=${url})`
+      );
+      ok(
+        !!win.gZenWorkspaces.getWorkspaceFromId(target),
+        "Redirect target must be an existing workspace"
+      );
+    }
+  }
+
+  clearAllRoutes();
+});
--- a/src/zen/tests/space_routing/browser_space_routing_redirect_navigation.js
+++ b/src/zen/tests/space_routing/browser_space_routing_redirect_navigation.js
@@ -0,0 +1,127 @@
+/* Any copyright is dedicated to the Public Domain.
+   https://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Exercises nsZenSpaceRoutingManager.shouldRedirectNavigation: an in-place
+// navigation is only redirected into a new tab when its rule points at a space
+// that differs from the one the navigating tab already lives in.
+
+const TARGET_WS = { uuid: "ws-target", containerTabId: 7 };
+
+add_setup(async function () {
+  clearAllRoutes();
+  registerCleanupFunction(() => clearAllRoutes());
+});
+
+add_task(async function test_redirect_when_route_targets_other_space() {
+  clearAllRoutes();
+  addRoute({
+    reference: "github.com",
+    matchType: "contains",
+    openIn: TARGET_WS.uuid,
+  });
+  const win = makeFakeWindow({ workspaces: [TARGET_WS] });
+
+  ok(
+    gZenSpaceRoutingManager.shouldRedirectNavigation(
+      "https://github.com/zen",
+      "ws-current",
+      win
+    ),
+    "Navigating to a routed site from a different space redirects"
+  );
+});
+
+add_task(async function test_no_redirect_when_already_in_target_space() {
+  clearAllRoutes();
+  addRoute({
+    reference: "github.com",
+    matchType: "contains",
+    openIn: TARGET_WS.uuid,
+  });
+  const win = makeFakeWindow({ workspaces: [TARGET_WS] });
+
+  ok(
+    !gZenSpaceRoutingManager.shouldRedirectNavigation(
+      "https://github.com/zen",
+      TARGET_WS.uuid,
+      win
+    ),
+    "Already in the destination space navigates in place (and avoids a loop)"
+  );
+});
+
+add_task(async function test_no_redirect_when_no_rule_matches() {
+  clearAllRoutes();
+  const win = makeFakeWindow({ workspaces: [TARGET_WS] });
+
+  ok(
+    !gZenSpaceRoutingManager.shouldRedirectNavigation(
+      "https://example.com",
+      "ws-current",
+      win
+    ),
+    "An unmatched URL is never redirected"
+  );
+});
+
+add_task(async function test_no_redirect_when_rule_targets_most_recent() {
+  clearAllRoutes();
+  addRoute({
+    reference: "github.com",
+    matchType: "contains",
+    openIn: "most-recent-space",
+  });
+  const win = makeFakeWindow({ workspaces: [TARGET_WS] });
+
+  ok(
+    !gZenSpaceRoutingManager.shouldRedirectNavigation(
+      "https://github.com",
+      "ws-current",
+      win
+    ),
+    "A rule that opens in the most recent space is not redirected"
+  );
+});
+
+add_task(async function test_no_redirect_when_target_workspace_missing() {
+  clearAllRoutes();
+  addRoute({
+    reference: "github.com",
+    matchType: "contains",
+    openIn: "ws-does-not-exist",
+  });
+  const win = makeFakeWindow({ workspaces: [TARGET_WS] });
+
+  ok(
+    !gZenSpaceRoutingManager.shouldRedirectNavigation(
+      "https://github.com",
+      "ws-current",
+      win
+    ),
+    "A rule pointing at a missing workspace is not redirected"
+  );
+});
+
+add_task(async function test_no_redirect_when_workspaces_disabled() {
+  clearAllRoutes();
+  addRoute({
+    reference: "github.com",
+    matchType: "contains",
+    openIn: TARGET_WS.uuid,
+  });
+  const win = makeFakeWindow({
+    workspaces: [TARGET_WS],
+    workspaceEnabled: false,
+  });
+
+  ok(
+    !gZenSpaceRoutingManager.shouldRedirectNavigation(
+      "https://github.com",
+      "ws-current",
+      win
+    ),
+    "Nothing is redirected when workspaces are disabled"
+  );
+});
--- a/src/zen/tests/space_routing/head.js
+++ b/src/zen/tests/space_routing/head.js
@@ -29,10 +29,15 @@ function addRoute({
  return route;
 }

-function makeFakeWindow({ ready = true, workspaces = [] } = {}) {
+function makeFakeWindow({
+  ready = true,
+  workspaces = [],
+  workspaceEnabled = true,
+} = {}) {
  return {
    gZenStartup: { isReady: ready },
    gZenWorkspaces: {
+      workspaceEnabled,
      moveCalls: [],
      changeCalls: [],
      lastSelectedWorkspaceTabs: {},
@@ -57,12 +62,17 @@ async function flushEventLoop() {
 }

 async function openRoutingDialog() {
-  const dialogPromise = BrowserTestUtils.domWindowOpenedAndLoaded(null, win =>
-    win.document?.documentURI?.includes("zen-space-routing.xhtml")
+  // openSpaceRoutingDialog() presents an in-window modal through gDialogBox, so
+  // the dialog is a subdialog rather than a separate top-level window.
+  const dialogPromise = BrowserTestUtils.promiseAlertDialogOpen(
+    null,
+    SR_DIALOG_URI,
+    { isSubDialog: true }
  );
+  // gDialogBox.open() only resolves once the dialog is dismissed, so kick it off
+  // without awaiting and wait on the open notification instead.
  executeSoon(() => gZenSpaceRoutingManager.openSpaceRoutingDialog(window));
  const dialogWin = await dialogPromise;
-  await SimpleTest.promiseFocus(dialogWin);
  await TestUtils.waitForCondition(
    () => dialogWin.spaceroutingDialog?.initialized,
    "Space Routing dialog finished initializing"
@@ -70,11 +80,23 @@ async function openRoutingDialog() {
  return dialogWin;
 }

-async function closeRoutingDialog(dialogWin) {
-  if (dialogWin.closed) {
-    return;
+// Resolves once the gDialogBox subdialog has fully torn down. Use this instead
+// of BrowserTestUtils.domWindowClosed(), which only fires for separate
+// top-level windows and so never resolves for an in-window subdialog.
+function promiseRoutingDialogClosed() {
+  const container = document.getElementById("window-modal-dialog");
+  if (!container?.open) {
+    return Promise.resolve();
  }
-  const closed = BrowserTestUtils.domWindowClosed(dialogWin);
+  return BrowserTestUtils.waitForMutationCondition(
+    container,
+    { childList: true, attributes: true },
+    () => !container.hasChildNodes() && !container.open
+  );
+}
+
+async function closeRoutingDialog(dialogWin) {
+  const closed = promiseRoutingDialogClosed();
  dialogWin.close();
  await closed;
 }
--- a/src/zen/tests/spaces/browser.toml
+++ b/src/zen/tests/spaces/browser.toml
@@ -26,6 +26,8 @@ support-files = [

 ["browser_private_mode_startup.js"]

+["browser_select_tab_switches_space.js"]
+
 ["browser_unload_all_other_spaces.js"]

 ["browser_workspace_bookmarks.js"]
--- a/src/zen/tests/spaces/browser_select_tab_switches_space.js
+++ b/src/zen/tests/spaces/browser_select_tab_switches_space.js
@@ -0,0 +1,69 @@
+/* Any copyright is dedicated to the Public Domain.
+   https://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function fakeTab(workspaceId) {
+  return {
+    getAttribute(name) {
+      return name === "zen-workspace-id" ? workspaceId : null;
+    },
+  };
+}
+
+function withRecordedSwitch(fn) {
+  const calls = [];
+  gZenWorkspaces.changeWorkspaceWithID = id => {
+    calls.push(id);
+  };
+  try {
+    fn(calls);
+  } finally {
+    // Remove the own property so the prototype method shows through again.
+    delete gZenWorkspaces.changeWorkspaceWithID;
+  }
+}
+
+add_task(function test_switches_when_tab_in_other_space() {
+  withRecordedSwitch(calls => {
+    const otherSpace = gZenWorkspaces.activeWorkspace + "-different";
+    gZenWorkspaces.onBeforeTabSelect(fakeTab(otherSpace));
+    Assert.deepEqual(
+      calls,
+      [otherSpace],
+      "Selecting a tab from another space switches to that space"
+    );
+  });
+});
+
+add_task(function test_no_switch_when_tab_in_active_space() {
+  withRecordedSwitch(calls => {
+    const active = gZenWorkspaces.activeWorkspace;
+    Assert.ok(active, "Test relies on a non-empty active workspace");
+    gZenWorkspaces.onBeforeTabSelect(fakeTab(active));
+    Assert.deepEqual(
+      calls,
+      [],
+      "Selecting a tab already in the active space does not switch"
+    );
+  });
+});
+
+add_task(function test_no_switch_when_tab_has_no_space() {
+  withRecordedSwitch(calls => {
+    gZenWorkspaces.onBeforeTabSelect(fakeTab(null));
+    Assert.deepEqual(
+      calls,
+      [],
+      "A tab with no zen-workspace-id does not switch spaces"
+    );
+  });
+});
+
+add_task(function test_handles_missing_tab() {
+  withRecordedSwitch(calls => {
+    gZenWorkspaces.onBeforeTabSelect(null);
+    gZenWorkspaces.onBeforeTabSelect(undefined);
+    Assert.deepEqual(calls, [], "A missing tab is ignored without throwing");
+  });
+});