diff --git a/.changeset/fn-4238-export-merger-errors.md b/.changeset/fn-4238-export-merger-errors.md
new file mode 100644
index 000000000..b189d81d3
--- /dev/null
+++ b/.changeset/fn-4238-export-merger-errors.md
@@ -0,0 +1,5 @@
+---
+"@runfusion/fusion": minor
+---
+
+Export `DiffVolumeRegressionError`, `MergeAbortedError`, and `SquashAuditError` from `@fusion/engine` so consumers can use `instanceof` checks without deep-importing.
diff --git a/packages/dashboard/app/components/WorkflowResultsTab.css b/packages/dashboard/app/components/WorkflowResultsTab.css
index cbebf2fc4..0b241f3d2 100644
--- a/packages/dashboard/app/components/WorkflowResultsTab.css
+++ b/packages/dashboard/app/components/WorkflowResultsTab.css
@@ -54,19 +54,13 @@
 
 .workflow-results-edit-toggle {
   width: auto;
-  height: calc(var(--space-lg) * 2 - var(--space-xs));
-  padding: 0 calc(var(--space-sm) + var(--space-xs) * 0.5);
-  border: 1px solid var(--border);
-  border-radius: var(--radius-sm);
-  background: var(--surface);
+  min-height: calc(var(--space-lg) * 2 - var(--space-xs));
+  padding-inline: calc(var(--space-sm) + var(--space-xs) * 0.5);
   color: var(--text-muted);
-  font-size: calc(var(--space-sm) + var(--space-xs));
-  font-weight: 500;
   gap: calc(var(--space-xs) + var(--space-xs) * 0.5);
 }
 
 .workflow-results-edit-toggle:hover {
-  background: var(--card-hover);
   color: var(--text);
 }
 
@@ -229,7 +223,7 @@
 /* Phase badge base and modifier classes */
 .phase-badge {
   margin-inline-start: var(--space-xs);
-  font-size: 11px;
+  font-size: calc(var(--space-sm) + var(--space-xs) * 0.75);
   padding: var(--space-xs) var(--space-sm);
   border-radius: var(--radius-sm);
 }
@@ -293,6 +287,7 @@
 
 .workflow-result-output-header {
   display: flex;
+  flex-wrap: wrap;
   align-items: center;
   gap: var(--space-sm);
   margin-bottom: var(--space-xs);
@@ -307,6 +302,8 @@
 }
 
 .workflow-result-output-preview {
+  flex: 1 1 calc(var(--space-2xl) * 6);
+  min-width: 0;
   font-size: calc(var(--space-sm) + var(--space-xs) * 0.75);
   color: var(--text-dim);
   font-style: italic;
@@ -504,6 +501,19 @@
     min-height: calc(var(--space-lg) * 2 + var(--space-xs));
   }
 
+  .workflow-result-output-header {
+    align-items: flex-start;
+  }
+
+  .workflow-result-output-preview {
+    flex-basis: 100%;
+    order: 3;
+  }
+
+  .workflow-result-mode-toggle {
+    margin-left: 0;
+  }
+
   .workflow-configured-header {
     align-items: flex-start;
   }
diff --git a/packages/dashboard/app/components/WorkflowResultsTab.tsx b/packages/dashboard/app/components/WorkflowResultsTab.tsx
index b19c1f07b..0771a2fb3 100644
--- a/packages/dashboard/app/components/WorkflowResultsTab.tsx
+++ b/packages/dashboard/app/components/WorkflowResultsTab.tsx
@@ -570,7 +570,7 @@ export function WorkflowResultsTab({
   const editButton = canEdit ? (
     <button
       type="button"
-      className="modal-edit-btn workflow-results-edit-toggle"
+      className="btn btn-sm workflow-results-edit-toggle"
       onClick={() => setIsEditing((prev) => !prev)}
       data-testid="workflow-steps-edit-toggle"
       aria-label={isEditing ? "Done editing workflow steps" : "Edit workflow steps"}
diff --git a/packages/dashboard/app/components/__tests__/WorkflowResultsTab.test.tsx b/packages/dashboard/app/components/__tests__/WorkflowResultsTab.test.tsx
index 79715b12f..b5a2b7d99 100644
--- a/packages/dashboard/app/components/__tests__/WorkflowResultsTab.test.tsx
+++ b/packages/dashboard/app/components/__tests__/WorkflowResultsTab.test.tsx
@@ -873,6 +873,17 @@ describe("WorkflowResultsTab", () => {
       expect(css).toMatch(/\.workflow-output-modal-name\s*\{[^}]*min-width:\s*0;[^}]*overflow-wrap:\s*anywhere;/);
     });
 
+    it("keeps workflow output header actions visible without hardcoded badge sizing", () => {
+      const baseCss = loadAllAppCssBaseOnly();
+      const allCss = loadAllAppCss();
+
+      expect(baseCss).toMatch(/\.phase-badge\s*\{[^}]*font-size:\s*calc\(var\(--space-sm\) \+ var\(--space-xs\) \* 0\.75\);/);
+      expect(baseCss).toMatch(/\.workflow-result-output-header\s*\{[^}]*flex-wrap:\s*wrap;/);
+      expect(baseCss).toMatch(/\.workflow-result-output-preview\s*\{[^}]*flex:\s*1 1 calc\(var\(--space-2xl\) \* 6\);[^}]*min-width:\s*0;/);
+      expect(allCss).toMatch(/@media \(max-width: 768px\)\s*\{[\s\S]*?\.workflow-result-output-preview\s*\{[^}]*flex-basis:\s*100%;[^}]*order:\s*3;/);
+      expect(allCss).toMatch(/@media \(max-width: 768px\)\s*\{[\s\S]*?\.workflow-result-mode-toggle\s*\{[^}]*margin-left:\s*0;/);
+    });
+
     it("allows workflow modal controls to wrap on mobile so the close button stays visible", () => {
       const css = loadAllAppCss();
 
diff --git a/packages/engine/src/__tests__/engine-public-api.test.ts b/packages/engine/src/__tests__/engine-public-api.test.ts
new file mode 100644
index 000000000..e2f16ab56
--- /dev/null
+++ b/packages/engine/src/__tests__/engine-public-api.test.ts
@@ -0,0 +1,60 @@
+import { describe, expect, it } from "vitest";
+import {
+  BranchConflictError,
+  DiffVolumeRegressionError,
+  MergeAbortedError,
+  SquashAuditError,
+  type SquashAuditFindings,
+} from "../index.js";
+
+const emptySquashAuditFindings: SquashAuditFindings = {
+  strategy: "squash",
+  squashSha: "abc12345",
+  parentSha: "def67890",
+  squashSubject: "squash subject",
+  auditTargetLabel: "abc12345",
+  lookback: 30,
+  branchSubjects: [],
+  recentMainSubjects: [],
+  duplicateSubjects: [],
+  touchedFiles: [],
+  touchedFileOverlaps: [],
+  findings: [],
+  issueCount: 0,
+  clean: true,
+};
+
+describe("engine public api barrel", () => {
+  it.each([
+    {
+      name: "BranchConflictError",
+      ctor: () => new BranchConflictError({
+        branchName: "task/fn-4238",
+        conflictingWorktreePath: "/tmp/worktree",
+        existingTipSha: "0123456789ab",
+        strandedCommits: [],
+        startPoint: "main",
+        recommendedAction: "Rebase the task branch.",
+      }),
+    },
+    {
+      name: "DiffVolumeRegressionError",
+      ctor: () => new DiffVolumeRegressionError([]),
+    },
+    {
+      name: "MergeAbortedError",
+      ctor: () => new MergeAbortedError("merge aborted"),
+    },
+    {
+      name: "SquashAuditError",
+      ctor: () => new SquashAuditError("FN-4238", "abc12345", emptySquashAuditFindings),
+    },
+  ])("exports $name from ../index.js", ({ name, ctor }) => {
+    expect(ctor).toBeTypeOf("function");
+
+    const error = ctor();
+
+    expect(error).toBeInstanceOf(Error);
+    expect(error.name).toBe(name);
+  });
+});
diff --git a/packages/engine/src/index.ts b/packages/engine/src/index.ts
index 9cde782b9..9035be0fa 100644
--- a/packages/engine/src/index.ts
+++ b/packages/engine/src/index.ts
@@ -28,6 +28,9 @@ export {
   dropAutostashBySha,
   getAutostashDiff,
   notifyAutostashOrphans,
+  DiffVolumeRegressionError,
+  MergeAbortedError,
+  SquashAuditError,
   type MergerOptions,
   type AutostashOrphanRecord,
 } from "./merger.js";