FN-5968: streamline Changes-tab mobile controls

Tighten the Task Changes toolbar so mobile diff navigation and actions stay compact.

- reuse a shared Changes header renderer so empty and populated states keep the same controls
- add mobile-specific Task Changes toolbar layout rules for wrapped navigation and secondary actions
- cover the mobile header structure, empty-diff actions, and publish a patch changeset

Files changed:
 .changeset/fn-5968-changes-tab-mobile.md           |   5 +
 packages/dashboard/app/components/TaskChangesTab.tsx    | 137 +++++++++++----------
 packages/dashboard/app/components/TaskDetailModal.css   |  39 ++++++
 packages/dashboard/app/components/__tests__/TaskChangesTab.test.tsx   | 103 +++++++++++++++-
 4 files changed, 216 insertions(+), 68 deletions(-)

Fusion-Task-Id: FN-5968

Fusion-Task-Lineage: 70865b8f-7f77-4cdb-aa0f-0d497d05e4ac

.changeset/fn-5968-changes-tab-mobile.md

@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": patch
+---
+
+Streamline the Task Changes tab header controls on mobile so diff navigation and actions use a more compact layout.

packages/dashboard/app/components/TaskChangesTab.tsx

@@ -217,6 +217,75 @@ export function TaskChangesTab({ taskId, worktree, projectId, column, mergeDetai
   const canGoPrev = currentFileIndex !== null && currentFileIndex > 0;
   const canGoNext = currentFileIndex !== null && currentFileIndex < files.length - 1;
 
+  const renderChangesHeader = () => (
+    <div className="changes-header">
+      <div className="task-changes-header-title">
+        <h4>
+          <FileCode size={16} />
+          {t("taskChanges.filesChangedHeading", "Files Changed ({{count}})", { count: stats.filesChanged })}
+        </h4>
+        <span className="task-changes-stats changes-stat-summary">
+          <span className="diff-add">+{stats.additions}</span>{" "}
+          <span className="diff-del">-{stats.deletions}</span>
+        </span>
+      </div>
+      <div className="changes-header-actions-wrapper">
+        <div className="changes-header-actions">
+          {files.length > 0 && (
+            <div className="changes-nav">
+              <button
+                className="btn btn-sm btn-icon"
+                onClick={() => canGoPrev && navigateToFile(currentFileIndex! - 1)}
+                disabled={!canGoPrev}
+                title={t("taskChanges.previousFile", "Previous file")}
+                aria-label={t("taskChanges.previousFile", "Previous file")}
+              >
+                <ChevronLeft />
+              </button>
+              <span className="changes-nav-indicator" aria-live="polite">
+                {currentFileIndex !== null ? `${currentFileIndex + 1}/${files.length}` : `—/${files.length}`}
+              </span>
+              <button
+                className="btn btn-sm btn-icon"
+                onClick={() => canGoNext && navigateToFile(currentFileIndex! + 1)}
+                disabled={!canGoNext}
+                title={t("taskChanges.nextFile", "Next file")}
+                aria-label={t("taskChanges.nextFile", "Next file")}
+              >
+                <ChevronRight />
+              </button>
+            </div>
+          )}
+          <button
+            className={`btn btn-sm ${wordWrap ? "btn-primary" : ""}`}
+            onClick={() => setWordWrap((prev) => !prev)}
+            title={t(`taskChanges.${wordWrap ? "disableWordWrap" : "enableWordWrap"}`, wordWrap ? "Disable word wrap" : "Enable word wrap")}
+            aria-label={t("taskChanges.toggleWordWrap", "Toggle word wrap")}
+          >
+            <WrapText size={14} />
+          </button>
+        </div>
+        <div className="changes-header-actions-secondary">
+          <button
+            className="btn btn-sm"
+            onClick={loadDiff}
+            disabled={loading}
+          >
+            {t("common.refresh", "Refresh")}
+          </button>
+          <button
+            className="btn btn-sm btn-icon"
+            onClick={() => setExpandedViewOpen(true)}
+            title={t("taskChanges.expandDiff", "Expand to full-screen diff view")}
+            aria-label={t("taskChanges.expandDiffView", "Expand diff view")}
+          >
+            <Maximize2 />
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+
   if (loading) {
     return (
       <div className="detail-section">
@@ -294,6 +363,7 @@ export function TaskChangesTab({ taskId, worktree, projectId, column, mergeDetai
 
     return (
       <div className="detail-section task-changes-tab">
+        {renderChangesHeader()}
         <div className="task-changes-state task-changes-state--empty">
           <FileCode size={24} />
           <p>{t("taskChanges.noFilesModified", "No files modified.")}</p>
@@ -335,72 +405,7 @@ export function TaskChangesTab({ taskId, worktree, projectId, column, mergeDetai
         </div>
       )}
 
-      <div className="changes-header">
-        <div className="task-changes-header-title">
-          <h4>
-            <FileCode size={16} />
-            {t("taskChanges.filesChangedHeading", "Files Changed ({{count}})", { count: stats.filesChanged })}
-          </h4>
-          <span className="task-changes-stats changes-stat-summary">
-            <span className="diff-add">+{stats.additions}</span>{" "}
-            <span className="diff-del">-{stats.deletions}</span>
-          </span>
-        </div>
-        <div className="changes-header-actions-wrapper">
-          <div className="changes-header-actions">
-            {files.length > 0 && (
-              <div className="changes-nav">
-                <button
-                  className="btn btn-sm btn-icon"
-                  onClick={() => canGoPrev && navigateToFile(currentFileIndex! - 1)}
-                  disabled={!canGoPrev}
-                  title={t("taskChanges.previousFile", "Previous file")}
-                  aria-label={t("taskChanges.previousFile", "Previous file")}
-                >
-                  <ChevronLeft />
-                </button>
-                <span className="changes-nav-indicator" aria-live="polite">
-                  {currentFileIndex !== null ? `${currentFileIndex + 1}/${files.length}` : `—/${files.length}`}
-                </span>
-                <button
-                  className="btn btn-sm btn-icon"
-                  onClick={() => canGoNext && navigateToFile(currentFileIndex! + 1)}
-                  disabled={!canGoNext}
-                  title={t("taskChanges.nextFile", "Next file")}
-                  aria-label={t("taskChanges.nextFile", "Next file")}
-                >
-                  <ChevronRight />
-                </button>
-              </div>
-            )}
-            <button
-              className={`btn btn-sm ${wordWrap ? "btn-primary" : ""}`}
-              onClick={() => setWordWrap((prev) => !prev)}
-              title={t(`taskChanges.${wordWrap ? "disableWordWrap" : "enableWordWrap"}`, wordWrap ? "Disable word wrap" : "Enable word wrap")}
-              aria-label={t("taskChanges.toggleWordWrap", "Toggle word wrap")}
-            >
-              <WrapText size={14} />
-            </button>
-          </div>
-          <div className="changes-header-actions-secondary">
-            <button
-              className="btn btn-sm"
-              onClick={loadDiff}
-              disabled={loading}
-            >
-              {t("common.refresh", "Refresh")}
-            </button>
-            <button
-              className="btn btn-sm btn-icon"
-              onClick={() => setExpandedViewOpen(true)}
-              title={t("taskChanges.expandDiff", "Expand to full-screen diff view")}
-              aria-label={t("taskChanges.expandDiffView", "Expand diff view")}
-            >
-              <Maximize2 />
-            </button>
-          </div>
-        </div>
-      </div>
+      {renderChangesHeader()}
 
       <div className="changes-file-list task-changes-file-list--compact">
         {files.map((file) => {

packages/dashboard/app/components/TaskDetailModal.css

@@ -1166,6 +1166,45 @@
   margin-left: calc(var(--space-lg) + var(--space-sm)); /* align with text after icon + gap */
 }
 
+@media (max-width: 768px) {
+  .task-changes-tab .changes-header {
+    align-items: stretch;
+    gap: var(--space-sm);
+  }
+
+  .task-changes-tab .changes-header-actions-wrapper {
+    width: 100%;
+    flex-direction: row;
+    flex-wrap: wrap;
+    align-items: center;
+    justify-content: flex-start;
+    gap: var(--space-sm);
+  }
+
+  .task-changes-tab .changes-header-actions,
+  .task-changes-tab .changes-header-actions-secondary {
+    flex-wrap: wrap;
+    gap: var(--space-sm);
+  }
+
+  .task-changes-tab .changes-header-actions {
+    flex: 1 1 auto;
+    min-width: 0;
+  }
+
+  .task-changes-tab .changes-header-actions-secondary {
+    margin-left: auto;
+  }
+
+  .task-changes-tab .task-changes-header-title {
+    gap: var(--space-xs);
+  }
+
+  .task-changes-tab .task-changes-stats {
+    margin-left: calc(var(--space-lg) + var(--space-xs));
+  }
+}
+
 /* Truncate parent dirs from the LEFT so the filename stays visible. JSX
  * wraps the path in `<bdo dir="ltr">` to preserve readable left-to-right
  * display while `direction: rtl` flips the ellipsis to the start. */

packages/dashboard/app/components/__tests__/TaskChangesTab.test.tsx

@@ -1053,7 +1053,7 @@ describe("TaskChangesTab — expand button", () => {
     expect(screen.getByTestId("changes-diff-modal")).toBeTruthy();
   });
 
-  it("does not render expand button when no files are loaded", async () => {
+  it("keeps the expand button available when no files are loaded", async () => {
     mockFetchTaskDiff.mockResolvedValue({
       files: [],
       stats: { filesChanged: 0, additions: 0, deletions: 0 },
@@ -1072,7 +1072,7 @@ describe("TaskChangesTab — expand button", () => {
       expect(screen.getByText("No files modified.")).toBeTruthy();
     });
 
-    expect(screen.queryByLabelText("Expand diff view")).toBeNull();
+    expect(screen.getByLabelText("Expand diff view")).toBeTruthy();
   });
 });
 
@@ -1224,6 +1224,105 @@ describe("TaskChangesTab — file path display", () => {
   });
 });
 
+describe("TaskChangesTab — header toolbar structure", () => {
+  it("keeps nav and controls grouped inside the header actions wrapper for populated diffs", async () => {
+    mockFetchTaskDiff.mockResolvedValue(DONE_TASK_DIFF);
+    const { container } = render(
+      <TaskChangesTab
+        taskId="FN-001"
+        worktree={undefined}
+        column="done"
+        mergeDetails={MERGE_DETAILS}
+      />,
+    );
+
+    await waitFor(() => {
+      expect(screen.getByText("Files Changed (2)")).toBeTruthy();
+    });
+
+    const header = container.querySelector(".task-changes-tab .changes-header");
+    const actionsWrapper = header?.querySelector(".changes-header-actions-wrapper");
+    const primaryActions = actionsWrapper?.querySelector(".changes-header-actions");
+    const secondaryActions = actionsWrapper?.querySelector(".changes-header-actions-secondary");
+    const nav = primaryActions?.querySelector(".changes-nav");
+
+    expect(actionsWrapper).toBeTruthy();
+    expect(primaryActions).toBeTruthy();
+    expect(secondaryActions).toBeTruthy();
+    expect(nav).toBeTruthy();
+    expect(nav?.querySelector('[aria-label="Previous file"]')).toBeTruthy();
+    expect(nav?.querySelector('[aria-label="Next file"]')).toBeTruthy();
+    expect(nav?.querySelector(".changes-nav-indicator")?.textContent).toBe("1/2");
+    expect(screen.getByLabelText("Toggle word wrap").closest(".changes-header-actions")).toBe(primaryActions ?? null);
+    expect(screen.getByText("Refresh").closest(".changes-header-actions-secondary")).toBe(secondaryActions ?? null);
+    expect(screen.getByLabelText("Expand diff view").closest(".changes-header-actions-secondary")).toBe(secondaryActions ?? null);
+  });
+
+  it("renders the header controls without nav when the diff is empty", async () => {
+    mockFetchTaskDiff.mockResolvedValue({
+      files: [],
+      stats: { filesChanged: 0, additions: 0, deletions: 0 },
+    });
+
+    const { container } = render(
+      <TaskChangesTab
+        taskId="FN-001"
+        worktree="/path/to/worktree"
+        column="in-progress"
+      />,
+    );
+
+    await waitFor(() => {
+      expect(screen.getByText("No files modified.")).toBeTruthy();
+    });
+
+    const header = container.querySelector(".task-changes-tab .changes-header");
+    const actionsWrapper = header?.querySelector(".changes-header-actions-wrapper");
+
+    expect(header).toBeTruthy();
+    expect(actionsWrapper).toBeTruthy();
+    expect(header?.querySelector(".changes-nav")).toBeNull();
+    expect(screen.getByLabelText("Toggle word wrap")).toBeTruthy();
+    expect(screen.getByText("Refresh")).toBeTruthy();
+    expect(screen.getByLabelText("Expand diff view")).toBeTruthy();
+  });
+
+  it("keeps commit metadata above the header while preserving the actions structure", async () => {
+    mockFetchTaskDiff.mockResolvedValue(DONE_TASK_DIFF);
+    const { container } = render(
+      <TaskChangesTab
+        taskId="FN-001"
+        worktree={undefined}
+        column="done"
+        mergeDetails={MERGE_DETAILS}
+      />,
+    );
+
+    await waitFor(() => {
+      expect(screen.getByText("Files Changed (2)")).toBeTruthy();
+    });
+
+    const taskTab = container.querySelector(".task-changes-tab");
+    const header = taskTab?.querySelector(":scope > .changes-header");
+    const commitMeta = taskTab?.querySelector(":scope > .commit-diff-meta");
+
+    expect(commitMeta).toBeTruthy();
+    expect(header).toBeTruthy();
+    expect(commitMeta?.nextElementSibling).toBe(header ?? null);
+    expect(header?.querySelector(".changes-header-actions-wrapper .changes-header-actions-secondary")).toBeTruthy();
+  });
+
+  it("defines task-scoped mobile toolbar overrides without changing shared desktop rules", () => {
+    const css = loadAllAppCss();
+    const mobileToolbarRule = css.match(/@media\s*\(max-width:\s*768px\)\s*\{[\s\S]*?\.task-changes-tab\s+\.changes-header-actions-wrapper\s*\{([\s\S]*?)\}/);
+
+    expect(mobileToolbarRule).toBeTruthy();
+    expect(mobileToolbarRule![1]).toContain("flex-direction: row;");
+    expect(mobileToolbarRule![1]).toContain("flex-wrap: wrap;");
+    expect(mobileToolbarRule![1]).toContain("width: 100%;");
+  });
+});
+
 describe("TaskChangesTab — action button sizing", () => {
   it("keeps Refresh and expand buttons on the same compact height", () => {
     const css = loadAllAppCss();