diff --git a/webui/src/api/workflow.ts b/webui/src/api/workflow.ts
index d1bbc6e..81aae9e 100644
--- a/webui/src/api/workflow.ts
+++ b/webui/src/api/workflow.ts
@@ -160,6 +160,29 @@ export type WorkflowStandardProvenance = {
   reset_available: boolean;
 };
 
+export type WorkflowStandardDiffItem = {
+  resource_type: "graph" | "node" | "edge";
+  resource_id: string;
+  state: "unchanged" | "local_only" | "upstream_only" | "same_change" | "conflict";
+  recommended_action: "none" | "keep_local" | "adopt_upstream" | "either" | "manual_resolution";
+  changed_fields: string[];
+  baseline?: Record<string, unknown> | null;
+  local?: Record<string, unknown> | null;
+  latest?: Record<string, unknown> | null;
+};
+
+export type WorkflowStandardDiff = {
+  override_definition_id: string;
+  baseline_definition_id: string;
+  pinned_baseline_revision: number;
+  local_revision: number;
+  latest_baseline_revision: number;
+  counts: Record<string, number>;
+  conflict_count: number;
+  auto_mergeable: boolean;
+  items: WorkflowStandardDiffItem[];
+};
+
 export type WorkflowDefinition = {
   id: string;
   tenant_id: string | null;
@@ -457,6 +480,16 @@ export function resetWorkflowDefinitionToStandard(
   );
 }
 
+export function compareWorkflowDefinitionToStandard(
+  settings: ApiSettings,
+  definitionId: string
+): Promise<WorkflowStandardDiff> {
+  return apiFetch(
+    settings,
+    `/api/v1/workflow/definitions/${encodeURIComponent(definitionId)}/standard-diff`
+  );
+}
+
 export async function listWorkflowRevisions(
   settings: ApiSettings,
   definitionId: string
diff --git a/webui/src/features/workflow/WorkflowPage.tsx b/webui/src/features/workflow/WorkflowPage.tsx
index e53e4bb..8732959 100644
--- a/webui/src/features/workflow/WorkflowPage.tsx
+++ b/webui/src/features/workflow/WorkflowPage.tsx
@@ -45,11 +45,11 @@ import {
 import {
   activateWorkflowDefinition,
   archiveWorkflowDefinition,
+  compareWorkflowDefinitionToStandard,
   compileWorkflowBpmn,
   createWorkflowDefinition,
   deleteWorkflowDefinition,
   deriveWorkflowDefinition,
-  getWorkflowRevision,
   listWorkflowDefinitions,
   listWorkflowNodeTypes,
   listWorkflowRevisions,
@@ -63,7 +63,8 @@ import {
   type WorkflowDiagnostic,
   type WorkflowGraphEdge,
   type WorkflowNodeType,
-  type WorkflowRevision
+  type WorkflowRevision,
+  type WorkflowStandardDiff
 } from "../../api/workflow";
 import WorkflowCanvas, {
   updateWorkflowGraphNode
@@ -151,10 +152,6 @@ export default function WorkflowPage({
     () => definitions.find((item) => item.id === draft?.id) ?? null,
     [definitions, draft?.id]
   );
-  const baselineDefinition = useMemo(() => {
-    const baselineId = selectedDefinition?.standard?.baseline_definition_id;
-    return definitions.find((item) => item.id === baselineId) ?? null;
-  }, [definitions, selectedDefinition]);
   const dirty = Boolean(draft)
     && workflowFingerprint(draft) !== workflowFingerprint(savedDraft);
   const displayedGraph = historicalRevision?.graph ?? draft?.graph ?? null;
@@ -987,7 +984,6 @@ export default function WorkflowPage({
         open={compareOpen}
         settings={settings}
         override={selectedDefinition}
-        baseline={baselineDefinition}
         onClose={() => setCompareOpen(false)}
       />
       <WorkflowDefinitionSettingsDialog
@@ -1041,45 +1037,31 @@ function WorkflowStandardComparisonDialog({
   open,
   settings,
   override,
-  baseline,
   onClose
 }: {
   open: boolean;
   settings: ApiSettings;
   override: WorkflowDefinition | null;
-  baseline: WorkflowDefinition | null;
   onClose: () => void;
 }) {
-  const [pinned, setPinned] = useState<WorkflowRevision | null>(null);
-  const [latest, setLatest] = useState<WorkflowRevision | null>(null);
+  const [comparison, setComparison] = useState<WorkflowStandardDiff | null>(null);
   const [error, setError] = useState("");
-  const standard = override?.standard;
 
   useEffect(() => {
-    if (!open || !baseline || !standard) return;
+    if (!open || !override) return;
     let cancelled = false;
     setError("");
-    const pinnedRevision = standard.pinned_baseline_revision
-      ?? standard.active_baseline_revision
-      ?? 1;
-    void Promise.all([
-      getWorkflowRevision(settings, baseline.id, pinnedRevision),
-      getWorkflowRevision(
-        settings,
-        baseline.id,
-        standard.latest_baseline_revision
-      )
-    ]).then(([pinnedItem, latestItem]) => {
+    setComparison(null);
+    void compareWorkflowDefinitionToStandard(settings, override.id).then((result) => {
       if (cancelled) return;
-      setPinned(pinnedItem);
-      setLatest(latestItem);
+      setComparison(result);
     }).catch((loadError) => {
       if (!cancelled) setError(apiErrorMessage(loadError));
     });
     return () => {
       cancelled = true;
     };
-  }, [baseline, open, settings, standard]);
+  }, [open, override, settings]);
 
   return (
     <Dialog
@@ -1094,44 +1076,79 @@ function WorkflowStandardComparisonDialog({
           {error}
         </DismissibleAlert>
       ) : null}
-      <div className="workflow-standard-comparison">
-        <StandardRevisionColumn
-          label="Pinned standard"
-          revision={pinned}
-        />
-        <StandardRevisionColumn
-          label="Local override"
-          revision={override?.revision ?? null}
-        />
-        <StandardRevisionColumn
-          label="Latest standard"
-          revision={latest}
-        />
-      </div>
+      {!error && !comparison ? <LoadingFrame label="Comparing workflow revisions..." /> : null}
+      {comparison ? (
+        <div className="workflow-standard-comparison">
+          <div className="workflow-standard-comparison-summary">
+            <span>
+              Pinned revision <strong>{comparison.pinned_baseline_revision}</strong>
+            </span>
+            <span>
+              Local revision <strong>{comparison.local_revision}</strong>
+            </span>
+            <span>
+              Latest standard <strong>{comparison.latest_baseline_revision}</strong>
+            </span>
+            <StatusBadge
+              status={comparison.auto_mergeable ? "ready" : "warning"}
+              label={comparison.auto_mergeable
+                ? "No semantic conflicts"
+                : `${comparison.conflict_count} conflicts`}
+            />
+          </div>
+          <div className="workflow-standard-diff-list">
+            {comparison.items.map((item) => (
+              <section
+                className={`workflow-standard-diff-item state-${item.state}`}
+                key={`${item.resource_type}:${item.resource_id}`}
+              >
+                <header>
+                  <span>
+                    <strong>{item.resource_id}</strong>
+                    <small>{item.resource_type} · {item.changed_fields.join(", ")}</small>
+                  </span>
+                  <StatusBadge
+                    status={item.state === "conflict"
+                      ? "warning"
+                      : item.state === "upstream_only"
+                        ? "queued"
+                        : "active"}
+                    label={standardDiffLabel(item.state)}
+                  />
+                </header>
+                <p>{standardDiffAction(item.recommended_action)}</p>
+              </section>
+            ))}
+            {!comparison.items.length ? (
+              <p className="workflow-standard-diff-empty">
+                The local override and latest standard contain no semantic changes.
+              </p>
+            ) : null}
+          </div>
+        </div>
+      ) : null}
     </Dialog>
   );
 }
 
-function StandardRevisionColumn({
-  label,
-  revision
-}: {
-  label: string;
-  revision: WorkflowRevision | null;
-}) {
-  return (
-    <section className="workflow-standard-revision">
-      <header>
-        <strong>{label}</strong>
-        <small>
-          {revision
-            ? `Revision ${revision.revision} · ${revision.content_hash.slice(0, 12)}`
-            : "Loading..."}
-        </small>
-      </header>
-      <pre>{revision ? JSON.stringify(revision.graph, null, 2) : ""}</pre>
-    </section>
-  );
+function standardDiffLabel(state: string): string {
+  return ({
+    local_only: "Local change",
+    upstream_only: "Standard update",
+    same_change: "Same change",
+    conflict: "Conflict",
+    unchanged: "Unchanged"
+  } as Record<string, string>)[state] ?? state;
+}
+
+function standardDiffAction(action: string): string {
+  return ({
+    keep_local: "The local change can be retained automatically.",
+    adopt_upstream: "The standard update can be adopted automatically.",
+    either: "Both revisions made the same semantic change.",
+    manual_resolution: "Local and upstream changes overlap and need a decision.",
+    none: "No action is required."
+  } as Record<string, string>)[action] ?? action;
 }
 
 function WorkflowDefinitionSettingsDialog({
diff --git a/webui/src/styles/workflow.css b/webui/src/styles/workflow.css
index dacb806..e15b8a6 100644
--- a/webui/src/styles/workflow.css
+++ b/webui/src/styles/workflow.css
@@ -19,55 +19,83 @@
 }
 
 .workflow-standard-comparison {
-  display: grid;
-  grid-template-columns: repeat(3, minmax(0, 1fr));
+  display: flex;
+  flex-direction: column;
   height: 100%;
   min-height: 0;
   gap: 10px;
   overflow: hidden;
 }
 
-.workflow-standard-revision {
+.workflow-standard-comparison-summary {
   display: flex;
-  min-width: 0;
-  min-height: 0;
-  flex-direction: column;
+  align-items: center;
+  gap: 18px;
+  padding: 10px 12px;
   border: var(--border-line);
   border-radius: var(--radius-sm);
   background: var(--panel-soft);
-  overflow: hidden;
 }
 
-.workflow-standard-revision header {
+.workflow-standard-comparison-summary .status-badge {
+  margin-left: auto;
+}
+
+.workflow-standard-diff-list {
   display: grid;
-  gap: 3px;
-  padding: 10px;
-  border-bottom: var(--border-line);
-}
-
-.workflow-standard-revision small {
-  color: var(--muted);
-  font-size: 11px;
-}
-
-.workflow-standard-revision pre {
   min-height: 0;
-  flex: 1 1 auto;
-  margin: 0;
-  padding: 10px;
+  gap: 6px;
   overflow: auto;
-  font-size: 11px;
-  white-space: pre;
+}
+
+.workflow-standard-diff-item {
+  padding: 10px 12px;
+  border: var(--border-line);
+  border-left: 3px solid var(--success);
+  border-radius: var(--radius-sm);
+  background: var(--panel);
+}
+
+.workflow-standard-diff-item.state-conflict {
+  border-left-color: var(--warning);
+}
+
+.workflow-standard-diff-item.state-upstream_only {
+  border-left-color: var(--info-text-strong);
+}
+
+.workflow-standard-diff-item header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+}
+
+.workflow-standard-diff-item header > span {
+  display: grid;
+  min-width: 0;
+  gap: 2px;
+}
+
+.workflow-standard-diff-item small,
+.workflow-standard-diff-item p,
+.workflow-standard-diff-empty {
+  color: var(--muted);
+}
+
+.workflow-standard-diff-item p {
+  margin: 6px 0 0;
 }
 
 @media (max-width: 900px) {
-  .workflow-standard-comparison {
-    grid-template-columns: 1fr;
-    overflow: auto;
+  .workflow-standard-comparison-summary {
+    align-items: flex-start;
+    flex-direction: column;
+    gap: 5px;
   }
 
-  .workflow-standard-revision {
-    min-height: 260px;
+  .workflow-standard-comparison-summary .status-badge {
+    margin-left: 0;
   }
 }