diff --git a/.changeset/fn-8421-task-detail-tablet-control-heights.md b/.changeset/fn-8421-task-detail-tablet-control-heights.md
new file mode 100644
index 0000000000..797ccad48e
--- /dev/null
+++ b/.changeset/fn-8421-task-detail-tablet-control-heights.md
@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Task detail Oversight/Fast and chat send heights match sibling controls on tablet.
+category: fix
+dev: Completes FN-8287 class wiring on attach/github/priority; aliases detail shared square to Quick Add compact height tokens; equalizes Planner Chat input/send block size for tablet/desktop.
diff --git a/packages/dashboard/app/components/TaskDetailModal.css b/packages/dashboard/app/components/TaskDetailModal.css
index 3e77291057..6cd9eca4f2 100644
--- a/packages/dashboard/app/components/TaskDetailModal.css
+++ b/packages/dashboard/app/components/TaskDetailModal.css
@@ -336,6 +336,13 @@ The task-detail modal metadata must keep priority, execution mode, provenance, P
   and applies at every width, so no mobile-only override is needed here.
   */
   .detail-meta-inline-controls {
+    /*
+    FNXC:QuickAddActionRow 2026-07-20-12:00:
+    FN-8421 keeps the Task Detail action row at the mobile touch floor while
+    the default compact Quick Add alias serves desktop and tablet widths.
+    */
+    --detail-priority-control-min-height: var(--quick-entry-action-row-height-mobile);
+
     flex-wrap: wrap;
   }
 
@@ -382,7 +389,14 @@ The task-detail modal metadata must keep priority, execution mode, provenance, P
   low/high/urgent, oversight observe/steer/autonomous/off, execution-mode
   fast) are untouched.
   */
-  --detail-priority-control-min-height: calc(var(--space-lg) + var(--space-lg) + var(--space-xs));
+  /*
+  FNXC:QuickAddActionRow 2026-07-20-12:00:
+  FN-8421 completes FN-8287's shared-square contract. Desktop and tablet must
+  alias Quick Add's compact control token, not make every action equally tall
+  with the former space-calc box; the mobile rule above raises the same alias
+  to the touch-floor token.
+  */
+  --detail-priority-control-min-height: var(--quick-entry-action-row-height-desktop);
   --detail-control-border-radius: var(--radius-md);
 
   display: flex;
@@ -512,7 +526,6 @@ no raw colors so the tokenized-focus assertion stays green.
   display: inline-flex;
   align-items: center;
   gap: var(--space-xs);
-  padding-block: var(--space-xs);
 }
 
 .detail-execution-mode-toggle--fast {
@@ -698,7 +711,6 @@ affect its size or anchoring — only the trigger's box height changes.
 }
 
 .detail-oversight-menu-trigger {
-  padding-block: var(--space-xs);
   /*
   FNXC:PlannerOversight 2026-07-05-00:00:
   FN-7604 — this trigger is now the single universal surface at every
diff --git a/packages/dashboard/app/components/TaskDetailModal.tsx b/packages/dashboard/app/components/TaskDetailModal.tsx
index 9987e3b3ed..95f156841c 100644
--- a/packages/dashboard/app/components/TaskDetailModal.tsx
+++ b/packages/dashboard/app/components/TaskDetailModal.tsx
@@ -4287,11 +4287,16 @@ export function TaskDetailContent({
                 attach, GitHub tracking, Oversight, Priority, then Fast. The compact
                 controls delegate to the existing single file-input upload and
                 GitHub-tracking handlers so this row never forks persistence paths.
+
+                FNXC:QuickAddActionRow 2026-07-20-12:00:
+                FN-8421 completes FN-8287 sizing-class wiring: every mounted inline
+                action carries its shared-square class, preventing Oversight/Fast
+                from using a different tablet-height contract than its siblings.
                 */}
                 <div className="detail-meta-inline-controls" data-testid="detail-meta-inline-controls">
                   <button
                     type="button"
-                    className="btn btn-icon btn-sm"
+                    className="btn btn-icon btn-sm detail-inline-attach"
                     data-testid="detail-inline-attach"
                     onClick={() => fileInputRef.current?.click()}
                     disabled={uploading}
@@ -4303,7 +4308,7 @@ export function TaskDetailContent({
                   {canEditGithubTracking && !gitlabTrackedItem && (
                     <button
                       type="button"
-                      className={`btn btn-icon btn-sm ${githubTrackingEnabled ? "btn-primary" : ""}`}
+                      className={`btn btn-icon btn-sm detail-inline-github-toggle ${githubTrackingEnabled ? "btn-primary" : ""}`}
                       data-testid="detail-inline-github-toggle"
                       onClick={() => void handleToggleGithubTracking()}
                       disabled={isSavingGithubTracking}
@@ -4530,7 +4535,7 @@ export function TaskDetailContent({
                         */}
                         <button
                           type="button"
-                          className="btn btn-icon btn-sm"
+                          className="btn btn-icon btn-sm detail-priority-trigger"
                           data-testid="detail-priority-trigger"
                           onClick={() => setShowInlinePriorityPicker((isOpen) => !isOpen)}
                           disabled={isSavingInlinePriority}
diff --git a/packages/dashboard/app/components/TaskPlannerChatTab.css b/packages/dashboard/app/components/TaskPlannerChatTab.css
index 05b2e2ab94..037e6d7961 100644
--- a/packages/dashboard/app/components/TaskPlannerChatTab.css
+++ b/packages/dashboard/app/components/TaskPlannerChatTab.css
@@ -218,9 +218,19 @@ The Planner Chat streaming Stop button must occupy the same width footprint as t
   resize: vertical;
 }
 
+/*
+FNXC:TaskDetailPlannerChat 2026-07-20-12:00:
+FN-8421 extends the existing desktop/mobile composer parity to tablet, which
+inherits these base rules. Send and streaming Stop share this class, so pin
+its border-box block size and clear button padding to the textarea's compact
+height rather than relying on the global button minimum.
+*/
 .task-planner-chat-send {
   flex: 0 0 auto;
+  block-size: calc(var(--space-2xl) + var(--space-sm));
   min-block-size: calc(var(--space-2xl) + var(--space-sm));
+  box-sizing: border-box;
+  padding: 0;
   /* FN-7634: floor both the Send and Stop button variants (both carry this class) at the same width so the streaming swap never narrows or widens the control. */
   min-inline-size: var(--chat-input-control-size);
 }
diff --git a/packages/dashboard/app/components/__tests__/TaskDetailModal.rendering.test.tsx b/packages/dashboard/app/components/__tests__/TaskDetailModal.rendering.test.tsx
index ebe57c3f66..1c459d3b50 100644
--- a/packages/dashboard/app/components/__tests__/TaskDetailModal.rendering.test.tsx
+++ b/packages/dashboard/app/components/__tests__/TaskDetailModal.rendering.test.tsx
@@ -1431,6 +1431,14 @@ describe("TaskDetailModal", () => {
       expect(row.indexOf("detail-inline-github-toggle")).toBeLessThan(row.indexOf("detail-oversight-menu-trigger"));
       expect(row.indexOf("detail-oversight-menu-trigger")).toBeLessThan(row.indexOf("detail-priority-trigger"));
       expect(row.indexOf("detail-priority-trigger")).toBeLessThan(row.indexOf("detail-execution-mode-toggle"));
+      // FNXC:QuickAddActionRow 2026-07-20-12:00: Every test-id affordance must
+      // also carry its FN-8287 sizing class, including optional GitHub and
+      // Oversight surfaces, so mounted tablet controls share one compact box.
+      expect(row).toMatch(/className="btn btn-icon btn-sm detail-inline-attach"/);
+      expect(row).toMatch(/className=\{`btn btn-icon btn-sm detail-inline-github-toggle/);
+      expect(row).toMatch(/className="btn btn-icon btn-sm detail-oversight-menu-trigger"/);
+      expect(row).toMatch(/className="btn btn-icon btn-sm detail-priority-trigger"/);
+      expect(row).toMatch(/className=\{`btn btn-icon btn-sm detail-execution-mode-toggle/);
       for (const label of ["aria-label", "title"]) {
         expect(row.match(new RegExp(label, "g"))?.length).toBeGreaterThanOrEqual(5);
       }
diff --git a/packages/dashboard/app/components/__tests__/TaskDetailModal.responsive-and-dependencies.test.tsx b/packages/dashboard/app/components/__tests__/TaskDetailModal.responsive-and-dependencies.test.tsx
index 16e71163a5..e3b69405a7 100644
--- a/packages/dashboard/app/components/__tests__/TaskDetailModal.responsive-and-dependencies.test.tsx
+++ b/packages/dashboard/app/components/__tests__/TaskDetailModal.responsive-and-dependencies.test.tsx
@@ -291,6 +291,19 @@ describe("TaskDetailModal", () => {
       expect(sharedSizingBlock).toContain("border-width: var(--btn-border-width);");
       expect(sharedSizingBlock).toContain("border-color: var(--border);");
       expect(sharedSizingBlock).toContain("border-radius: var(--detail-control-border-radius);");
+
+      const inlineControlsBlock = getStandaloneCssRuleBlock(css, ".detail-meta-inline-controls");
+      const tabletBlock = getCssAtRuleBlockContaining(css, "@media (min-width: 769px) and (max-width: 1024px)", ".modal.task-detail-modal");
+      const mobileBlock = getCssAtRuleBlockContaining(css, "@media (max-width: 768px)", ".detail-meta-inline-controls");
+      const mobileInlineControlsBlock = getCssRuleBlock(mobileBlock, ".detail-meta-inline-controls");
+
+      // FNXC:QuickAddActionRow 2026-07-20-12:00: Equal boxes are insufficient:
+      // desktop and tablet must use Quick Add's compact token, while mobile
+      // deliberately upgrades the same shared alias to its touch-floor token.
+      expect(inlineControlsBlock).toContain("--detail-priority-control-min-height: var(--quick-entry-action-row-height-desktop);");
+      expect(inlineControlsBlock).not.toContain("calc(var(--space-lg) + var(--space-lg) + var(--space-xs))");
+      expect(tabletBlock).not.toMatch(/\.detail-(?:oversight-menu-trigger|execution-mode-toggle)\s*\{[^}]*?(?:height|min-height|width|min-width):/);
+      expect(mobileInlineControlsBlock).toContain("--detail-priority-control-min-height: var(--quick-entry-action-row-height-mobile);");
     });
 
     it.skip("unifies border/radius/height across the Priority, Execution-mode, and Oversight quick controls (FN-7585)", () => {
diff --git a/packages/dashboard/app/components/__tests__/TaskPlannerChatTab.test.tsx b/packages/dashboard/app/components/__tests__/TaskPlannerChatTab.test.tsx
index 1c442493d3..1971a5110e 100644
--- a/packages/dashboard/app/components/__tests__/TaskPlannerChatTab.test.tsx
+++ b/packages/dashboard/app/components/__tests__/TaskPlannerChatTab.test.tsx
@@ -937,6 +937,33 @@ describe("TaskPlannerChatTab", () => {
     expect(mobileTextHideRule).toMatch(/span:not\(\.chat-input-stop-icon\)/);
   });
 
+  it("keeps Planner Chat input and send/stop height-parity across desktop, tablet, and mobile (FN-8421)", () => {
+    const mobileQueryStart = taskPlannerChatCss.indexOf("@media (max-width: 768px)");
+    const desktopAndTabletCss = mobileQueryStart >= 0 ? taskPlannerChatCss.slice(0, mobileQueryStart) : taskPlannerChatCss;
+    const desktopInputRule = desktopAndTabletCss.match(/\.task-planner-chat-input\s*\{[^}]*\}/)?.[0] ?? "";
+    const desktopSendRule = desktopAndTabletCss.match(/\.task-planner-chat-send\s*\{[^}]*\}/)?.[0] ?? "";
+    const mobileInputRule = taskPlannerChatCss.slice(mobileQueryStart).match(/\.task-planner-chat-input\s*\{[^}]*\}/)?.[0] ?? "";
+    const mobileSendRule = taskPlannerChatCss.slice(mobileQueryStart).match(/\.task-planner-chat-send\s*\{[^}]*\}/)?.[0] ?? "";
+
+    // FNXC:TaskDetailPlannerChat 2026-07-20-12:00: The base contract serves
+    // desktop and the 769–1024 tablet band; explicit border-box sizing and
+    // zero button padding prevent inherited `.btn` padding from re-inflating
+    // the Send or Stop variant above the textarea.
+    const desktopTabletHeight = "calc(var(--space-2xl) + var(--space-sm))";
+    const mobileHeight = "calc(var(--space-2xl) + var(--space-lg))";
+    expect(desktopInputRule).toContain(`height: ${desktopTabletHeight};`);
+    expect(desktopInputRule).toContain(`min-height: ${desktopTabletHeight};`);
+    expect(desktopSendRule).toContain(`block-size: ${desktopTabletHeight};`);
+    expect(desktopSendRule).toContain(`min-block-size: ${desktopTabletHeight};`);
+    expect(desktopSendRule).toContain("box-sizing: border-box;");
+    expect(desktopSendRule).toContain("padding: 0;");
+    expect(mobileInputRule).toContain(`height: ${mobileHeight};`);
+    expect(mobileInputRule).toContain(`min-height: ${mobileHeight};`);
+    expect(mobileSendRule).toContain(`block-size: ${mobileHeight};`);
+    expect(mobileSendRule).toContain(`min-block-size: ${mobileHeight};`);
+    expect(mobileSendRule).toContain("padding: 0;");
+  });
+
   it("renders live and stored thinking output through the standard chat surface", async () => {
     const user = userEvent.setup();
     mockFetchChatMessages.mockResolvedValueOnce({