diff --git a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/DetailController.java b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/DetailController.java
index 2bd6ea55..dc705523 100644
--- a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/DetailController.java
+++ b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/DetailController.java
@@ -49,7 +49,7 @@ public class DetailController {
     }
 
     @GetMapping("/{executionId}/processors/{index}/snapshot")
-    @Operation(summary = "Get exchange snapshot for a specific processor")
+    @Operation(summary = "Get exchange snapshot for a specific processor by index")
     @ApiResponse(responseCode = "200", description = "Snapshot data")
     @ApiResponse(responseCode = "404", description = "Snapshot not found")
     public ResponseEntity<Map<String, String>> getProcessorSnapshot(
@@ -69,4 +69,16 @@ public class DetailController {
 
         return ResponseEntity.ok(snapshot);
     }
+
+    @GetMapping("/{executionId}/processors/by-id/{processorId}/snapshot")
+    @Operation(summary = "Get exchange snapshot for a specific processor by processorId")
+    @ApiResponse(responseCode = "200", description = "Snapshot data")
+    @ApiResponse(responseCode = "404", description = "Snapshot not found")
+    public ResponseEntity<Map<String, String>> processorSnapshotById(
+            @PathVariable String executionId,
+            @PathVariable String processorId) {
+        return detailService.getProcessorSnapshot(executionId, processorId)
+            .map(ResponseEntity::ok)
+            .orElse(ResponseEntity.notFound().build());
+    }
 }
diff --git a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/diagram/ElkDiagramRenderer.java b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/diagram/ElkDiagramRenderer.java
index 25234df2..ae357cb3 100644
--- a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/diagram/ElkDiagramRenderer.java
+++ b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/diagram/ElkDiagramRenderer.java
@@ -13,6 +13,7 @@ import org.eclipse.elk.core.RecursiveGraphLayoutEngine;
 import org.eclipse.elk.core.options.CoreOptions;
 import org.eclipse.elk.core.options.Direction;
 import org.eclipse.elk.core.options.HierarchyHandling;
+import org.eclipse.elk.alg.layered.options.NodePlacementStrategy;
 import org.eclipse.elk.core.util.BasicProgressMonitor;
 import org.eclipse.elk.graph.ElkBendPoint;
 import org.eclipse.elk.graph.ElkEdge;
@@ -181,6 +182,8 @@ public class ElkDiagramRenderer implements DiagramRenderer {
         rootNode.setProperty(CoreOptions.SPACING_NODE_NODE, NODE_SPACING);
         rootNode.setProperty(CoreOptions.SPACING_EDGE_NODE, EDGE_SPACING);
         rootNode.setProperty(CoreOptions.HIERARCHY_HANDLING, HierarchyHandling.INCLUDE_CHILDREN);
+        rootNode.setProperty(org.eclipse.elk.alg.layered.options.LayeredOptions.NODE_PLACEMENT_STRATEGY,
+                NodePlacementStrategy.LINEAR_SEGMENTS);
 
         // Build index of all RouteNodes (flat list from graph + recursive children)
         Map<String, RouteNode> routeNodeMap = new HashMap<>();
diff --git a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/storage/PostgresExecutionStore.java b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/storage/PostgresExecutionStore.java
index 760cb5e2..61de0828 100644
--- a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/storage/PostgresExecutionStore.java
+++ b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/storage/PostgresExecutionStore.java
@@ -72,8 +72,9 @@ public class PostgresExecutionStore implements ExecutionStore {
                 INSERT INTO processor_executions (execution_id, processor_id, processor_type,
                     application_name, route_id, depth, parent_processor_id,
                     status, start_time, end_time, duration_ms, error_message, error_stacktrace,
-                    input_body, output_body, input_headers, output_headers, attributes)
-                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?::jsonb, ?::jsonb, ?::jsonb)
+                    input_body, output_body, input_headers, output_headers, attributes,
+                    loop_index, loop_size, split_index, split_size, multicast_index)
+                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?::jsonb, ?::jsonb, ?::jsonb, ?, ?, ?, ?, ?)
                 ON CONFLICT (execution_id, processor_id, start_time) DO UPDATE SET
                     status = EXCLUDED.status,
                     end_time = COALESCE(EXCLUDED.end_time, processor_executions.end_time),
@@ -84,7 +85,12 @@ public class PostgresExecutionStore implements ExecutionStore {
                     output_body = COALESCE(EXCLUDED.output_body, processor_executions.output_body),
                     input_headers = COALESCE(EXCLUDED.input_headers, processor_executions.input_headers),
                     output_headers = COALESCE(EXCLUDED.output_headers, processor_executions.output_headers),
-                    attributes = COALESCE(EXCLUDED.attributes, processor_executions.attributes)
+                    attributes = COALESCE(EXCLUDED.attributes, processor_executions.attributes),
+                    loop_index = COALESCE(EXCLUDED.loop_index, processor_executions.loop_index),
+                    loop_size = COALESCE(EXCLUDED.loop_size, processor_executions.loop_size),
+                    split_index = COALESCE(EXCLUDED.split_index, processor_executions.split_index),
+                    split_size = COALESCE(EXCLUDED.split_size, processor_executions.split_size),
+                    multicast_index = COALESCE(EXCLUDED.multicast_index, processor_executions.multicast_index)
                 """,
                 processors.stream().map(p -> new Object[]{
                         p.executionId(), p.processorId(), p.processorType(),
@@ -94,7 +100,9 @@ public class PostgresExecutionStore implements ExecutionStore {
                         p.endTime() != null ? Timestamp.from(p.endTime()) : null,
                         p.durationMs(), p.errorMessage(), p.errorStacktrace(),
                         p.inputBody(), p.outputBody(), p.inputHeaders(), p.outputHeaders(),
-                        p.attributes()
+                        p.attributes(),
+                        p.loopIndex(), p.loopSize(), p.splitIndex(), p.splitSize(),
+                        p.multicastIndex()
                 }).toList());
     }
 
@@ -113,6 +121,13 @@ public class PostgresExecutionStore implements ExecutionStore {
                 PROCESSOR_MAPPER, executionId);
     }
 
+    @Override
+    public Optional<ProcessorRecord> findProcessorById(String executionId, String processorId) {
+        String sql = "SELECT * FROM processor_executions WHERE execution_id = ? AND processor_id = ? LIMIT 1";
+        List<ProcessorRecord> results = jdbc.query(sql, PROCESSOR_MAPPER, executionId, processorId);
+        return results.isEmpty() ? Optional.empty() : Optional.of(results.get(0));
+    }
+
     private static final RowMapper<ExecutionRecord> EXECUTION_MAPPER = (rs, rowNum) ->
             new ExecutionRecord(
                     rs.getString("execution_id"), rs.getString("route_id"),
@@ -140,7 +155,12 @@ public class PostgresExecutionStore implements ExecutionStore {
                     rs.getString("error_message"), rs.getString("error_stacktrace"),
                     rs.getString("input_body"), rs.getString("output_body"),
                     rs.getString("input_headers"), rs.getString("output_headers"),
-                    rs.getString("attributes"));
+                    rs.getString("attributes"),
+                    rs.getObject("loop_index") != null ? rs.getInt("loop_index") : null,
+                    rs.getObject("loop_size") != null ? rs.getInt("loop_size") : null,
+                    rs.getObject("split_index") != null ? rs.getInt("split_index") : null,
+                    rs.getObject("split_size") != null ? rs.getInt("split_size") : null,
+                    rs.getObject("multicast_index") != null ? rs.getInt("multicast_index") : null);
 
     private static Instant toInstant(ResultSet rs, String column) throws SQLException {
         Timestamp ts = rs.getTimestamp(column);
diff --git a/cameleer3-server-app/src/main/resources/db/migration/V8__processor_iteration_fields.sql b/cameleer3-server-app/src/main/resources/db/migration/V8__processor_iteration_fields.sql
new file mode 100644
index 00000000..5adb0cce
--- /dev/null
+++ b/cameleer3-server-app/src/main/resources/db/migration/V8__processor_iteration_fields.sql
@@ -0,0 +1,5 @@
+ALTER TABLE processor_executions ADD COLUMN IF NOT EXISTS loop_index INTEGER;
+ALTER TABLE processor_executions ADD COLUMN IF NOT EXISTS loop_size INTEGER;
+ALTER TABLE processor_executions ADD COLUMN IF NOT EXISTS split_index INTEGER;
+ALTER TABLE processor_executions ADD COLUMN IF NOT EXISTS split_size INTEGER;
+ALTER TABLE processor_executions ADD COLUMN IF NOT EXISTS multicast_index INTEGER;
diff --git a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/DetailService.java b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/DetailService.java
index fd26e183..236aafc8 100644
--- a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/DetailService.java
+++ b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/DetailService.java
@@ -38,6 +38,18 @@ public class DetailService {
                 });
     }
 
+    public Optional<Map<String, String>> getProcessorSnapshot(String executionId, String processorId) {
+        return executionStore.findProcessorById(executionId, processorId)
+            .map(p -> {
+                Map<String, String> snapshot = new LinkedHashMap<>();
+                if (p.inputBody() != null) snapshot.put("inputBody", p.inputBody());
+                if (p.outputBody() != null) snapshot.put("outputBody", p.outputBody());
+                if (p.inputHeaders() != null) snapshot.put("inputHeaders", p.inputHeaders());
+                if (p.outputHeaders() != null) snapshot.put("outputHeaders", p.outputHeaders());
+                return snapshot;
+            });
+    }
+
     List<ProcessorNode> buildTree(List<ProcessorRecord> processors) {
         if (processors.isEmpty()) return List.of();
 
@@ -48,7 +60,10 @@ public class DetailService {
                     p.startTime(), p.endTime(),
                     p.durationMs() != null ? p.durationMs() : 0L,
                     p.errorMessage(), p.errorStacktrace(),
-                    parseAttributes(p.attributes())
+                    parseAttributes(p.attributes()),
+                    p.loopIndex(), p.loopSize(),
+                    p.splitIndex(), p.splitSize(),
+                    p.multicastIndex()
             ));
         }
 
diff --git a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/ProcessorNode.java b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/ProcessorNode.java
index 32cd14c4..f071352d 100644
--- a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/ProcessorNode.java
+++ b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/ProcessorNode.java
@@ -22,12 +22,20 @@ public final class ProcessorNode {
     private final String errorMessage;
     private final String errorStackTrace;
     private final Map<String, String> attributes;
+    private final Integer loopIndex;
+    private final Integer loopSize;
+    private final Integer splitIndex;
+    private final Integer splitSize;
+    private final Integer multicastIndex;
     private final List<ProcessorNode> children;
 
     public ProcessorNode(String processorId, String processorType, String status,
                          Instant startTime, Instant endTime, long durationMs,
                          String errorMessage, String errorStackTrace,
-                         Map<String, String> attributes) {
+                         Map<String, String> attributes,
+                         Integer loopIndex, Integer loopSize,
+                         Integer splitIndex, Integer splitSize,
+                         Integer multicastIndex) {
         this.processorId = processorId;
         this.processorType = processorType;
         this.status = status;
@@ -37,6 +45,11 @@ public final class ProcessorNode {
         this.errorMessage = errorMessage;
         this.errorStackTrace = errorStackTrace;
         this.attributes = attributes;
+        this.loopIndex = loopIndex;
+        this.loopSize = loopSize;
+        this.splitIndex = splitIndex;
+        this.splitSize = splitSize;
+        this.multicastIndex = multicastIndex;
         this.children = new ArrayList<>();
     }
 
@@ -53,5 +66,10 @@ public final class ProcessorNode {
     public String getErrorMessage() { return errorMessage; }
     public String getErrorStackTrace() { return errorStackTrace; }
     public Map<String, String> getAttributes() { return attributes; }
+    public Integer getLoopIndex() { return loopIndex; }
+    public Integer getLoopSize() { return loopSize; }
+    public Integer getSplitIndex() { return splitIndex; }
+    public Integer getSplitSize() { return splitSize; }
+    public Integer getMulticastIndex() { return multicastIndex; }
     public List<ProcessorNode> getChildren() { return List.copyOf(children); }
 }
diff --git a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/ingestion/IngestionService.java b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/ingestion/IngestionService.java
index c4fad6fa..f07f67a4 100644
--- a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/ingestion/IngestionService.java
+++ b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/ingestion/IngestionService.java
@@ -128,7 +128,10 @@ public class IngestionService {
                     p.getErrorMessage(), p.getErrorStackTrace(),
                     truncateBody(p.getInputBody()), truncateBody(p.getOutputBody()),
                     toJson(p.getInputHeaders()), toJson(p.getOutputHeaders()),
-                    toJson(p.getAttributes())
+                    toJson(p.getAttributes()),
+                    p.getLoopIndex(), p.getLoopSize(),
+                    p.getSplitIndex(), p.getSplitSize(),
+                    p.getMulticastIndex()
             ));
             if (p.getChildren() != null) {
                 flat.addAll(flattenProcessors(
diff --git a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/storage/ExecutionStore.java b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/storage/ExecutionStore.java
index ecc076dd..181dd8f9 100644
--- a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/storage/ExecutionStore.java
+++ b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/storage/ExecutionStore.java
@@ -16,6 +16,8 @@ public interface ExecutionStore {
 
     List<ProcessorRecord> findProcessors(String executionId);
 
+    Optional<ProcessorRecord> findProcessorById(String executionId, String processorId);
+
     record ExecutionRecord(
             String executionId, String routeId, String agentId, String applicationName,
             String status, String correlationId, String exchangeId,
@@ -33,6 +35,9 @@ public interface ExecutionStore {
             Instant startTime, Instant endTime, Long durationMs,
             String errorMessage, String errorStacktrace,
             String inputBody, String outputBody, String inputHeaders, String outputHeaders,
-            String attributes
+            String attributes,
+            Integer loopIndex, Integer loopSize,
+            Integer splitIndex, Integer splitSize,
+            Integer multicastIndex
     ) {}
 }
diff --git a/ui/src/api/openapi.json b/ui/src/api/openapi.json
index 3fe82c87..56e71656 100644
--- a/ui/src/api/openapi.json
+++ b/ui/src/api/openapi.json
@@ -2359,6 +2359,61 @@
         }
       }
     },
+    "/executions/{executionId}/processors/by-id/{processorId}/snapshot": {
+      "get": {
+        "tags": [
+          "Detail"
+        ],
+        "summary": "Get exchange snapshot for a processor by processorId",
+        "operationId": "getProcessorSnapshotById",
+        "parameters": [
+          {
+            "name": "executionId",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string"
+            }
+          },
+          {
+            "name": "processorId",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "Snapshot data",
+            "content": {
+              "*/*": {
+                "schema": {
+                  "type": "object",
+                  "additionalProperties": {
+                    "type": "string"
+                  }
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "Snapshot not found",
+            "content": {
+              "*/*": {
+                "schema": {
+                  "type": "object",
+                  "additionalProperties": {
+                    "type": "string"
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    },
     "/diagrams": {
       "get": {
         "tags": [
@@ -4588,8 +4643,25 @@
             "type": "integer",
             "format": "int64"
           },
-          "diagramNodeId": {
-            "type": "string"
+          "loopIndex": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "loopSize": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "splitIndex": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "splitSize": {
+            "type": "integer",
+            "format": "int32"
+          },
+          "multicastIndex": {
+            "type": "integer",
+            "format": "int32"
           },
           "errorMessage": {
             "type": "string"
@@ -4613,7 +4685,6 @@
         "required": [
           "attributes",
           "children",
-          "diagramNodeId",
           "durationMs",
           "endTime",
           "errorMessage",
diff --git a/ui/src/api/queries/executions.ts b/ui/src/api/queries/executions.ts
index 90a2e44b..681ea312 100644
--- a/ui/src/api/queries/executions.ts
+++ b/ui/src/api/queries/executions.ts
@@ -114,3 +114,25 @@ export function useProcessorSnapshot(
     enabled: !!executionId && index !== null,
   });
 }
+
+export function useProcessorSnapshotById(
+  executionId: string | null,
+  processorId: string | null,
+) {
+  return useQuery({
+    queryKey: ['executions', 'snapshot-by-id', executionId, processorId],
+    queryFn: async () => {
+      const { data, error } = await api.GET(
+        '/executions/{executionId}/processors/by-id/{processorId}/snapshot',
+        {
+          params: {
+            path: { executionId: executionId!, processorId: processorId! },
+          },
+        },
+      );
+      if (error) throw new Error('Failed to load snapshot');
+      return data!;
+    },
+    enabled: !!executionId && !!processorId,
+  });
+}
diff --git a/ui/src/api/schema.d.ts b/ui/src/api/schema.d.ts
index 79389d45..43de9ef7 100644
--- a/ui/src/api/schema.d.ts
+++ b/ui/src/api/schema.d.ts
@@ -735,6 +735,23 @@ export interface paths {
         patch?: never;
         trace?: never;
     };
+    "/executions/{executionId}/processors/by-id/{processorId}/snapshot": {
+        parameters: {
+            query?: never;
+            header?: never;
+            path?: never;
+            cookie?: never;
+        };
+        /** Get exchange snapshot for a processor by processorId */
+        get: operations["getProcessorSnapshotById"];
+        put?: never;
+        post?: never;
+        delete?: never;
+        options?: never;
+        head?: never;
+        patch?: never;
+        trace?: never;
+    };
     "/diagrams": {
         parameters: {
             query?: never;
@@ -1620,7 +1637,16 @@ export interface components {
             endTime: string;
             /** Format: int64 */
             durationMs: number;
-            diagramNodeId: string;
+            /** Format: int32 */
+            loopIndex?: number;
+            /** Format: int32 */
+            loopSize?: number;
+            /** Format: int32 */
+            splitIndex?: number;
+            /** Format: int32 */
+            splitSize?: number;
+            /** Format: int32 */
+            multicastIndex?: number;
             errorMessage: string;
             errorStackTrace: string;
             attributes: {
@@ -3637,6 +3663,42 @@ export interface operations {
             };
         };
     };
+    getProcessorSnapshotById: {
+        parameters: {
+            query?: never;
+            header?: never;
+            path: {
+                executionId: string;
+                processorId: string;
+            };
+            cookie?: never;
+        };
+        requestBody?: never;
+        responses: {
+            /** @description Snapshot data */
+            200: {
+                headers: {
+                    [name: string]: unknown;
+                };
+                content: {
+                    "*/*": {
+                        [key: string]: string;
+                    };
+                };
+            };
+            /** @description Snapshot not found */
+            404: {
+                headers: {
+                    [name: string]: unknown;
+                };
+                content: {
+                    "*/*": {
+                        [key: string]: string;
+                    };
+                };
+            };
+        };
+    };
     findByApplicationAndRoute: {
         parameters: {
             query: {
diff --git a/ui/src/components/ExecutionDiagram/DetailPanel.tsx b/ui/src/components/ExecutionDiagram/DetailPanel.tsx
new file mode 100644
index 00000000..74c90411
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/DetailPanel.tsx
@@ -0,0 +1,164 @@
+import { useState, useEffect } from 'react';
+import type { ProcessorNode, ExecutionDetail, DetailTab } from './types';
+import { useProcessorSnapshotById } from '../../api/queries/executions';
+import { InfoTab } from './tabs/InfoTab';
+import { HeadersTab } from './tabs/HeadersTab';
+import { BodyTab } from './tabs/BodyTab';
+import { ErrorTab } from './tabs/ErrorTab';
+import { ConfigTab } from './tabs/ConfigTab';
+import { TimelineTab } from './tabs/TimelineTab';
+import styles from './ExecutionDiagram.module.css';
+
+interface DetailPanelProps {
+  selectedProcessor: ProcessorNode | null;
+  executionDetail: ExecutionDetail;
+  executionId: string;
+  onSelectProcessor: (processorId: string) => void;
+}
+
+const TABS: { key: DetailTab; label: string }[] = [
+  { key: 'info', label: 'Info' },
+  { key: 'headers', label: 'Headers' },
+  { key: 'input', label: 'Input' },
+  { key: 'output', label: 'Output' },
+  { key: 'error', label: 'Error' },
+  { key: 'config', label: 'Config' },
+  { key: 'timeline', label: 'Timeline' },
+];
+
+function formatDuration(ms: number | undefined): string {
+  if (ms === undefined || ms === null) return '-';
+  if (ms < 1000) return `${ms}ms`;
+  return `${(ms / 1000).toFixed(1)}s`;
+}
+
+function statusClass(status: string): string {
+  const s = status?.toUpperCase();
+  if (s === 'COMPLETED') return styles.statusCompleted;
+  if (s === 'FAILED') return styles.statusFailed;
+  return '';
+}
+
+export function DetailPanel({
+  selectedProcessor,
+  executionDetail,
+  executionId,
+  onSelectProcessor,
+}: DetailPanelProps) {
+  const [activeTab, setActiveTab] = useState<DetailTab>('info');
+
+  // When selectedProcessor changes, keep current tab unless it was a
+  // processor-specific tab and now there is no processor selected.
+  const prevProcessorId = selectedProcessor?.processorId;
+  useEffect(() => {
+    // If no processor is selected and we're on a processor-specific tab, go to info
+    if (!selectedProcessor && (activeTab === 'input' || activeTab === 'output')) {
+      // Input/Output at exchange level still make sense, keep them
+    }
+  }, [prevProcessorId]); // eslint-disable-line react-hooks/exhaustive-deps
+
+  const hasError = selectedProcessor
+    ? !!selectedProcessor.errorMessage
+    : !!executionDetail.errorMessage;
+
+  // Fetch snapshot for body tabs when a processor is selected
+  const snapshotQuery = useProcessorSnapshotById(
+    selectedProcessor ? executionId : null,
+    selectedProcessor?.processorId ?? null,
+  );
+
+  // Determine body content for Input/Output tabs
+  let inputBody: string | undefined;
+  let outputBody: string | undefined;
+
+  if (selectedProcessor && snapshotQuery.data) {
+    inputBody = snapshotQuery.data.inputBody;
+    outputBody = snapshotQuery.data.outputBody;
+  } else if (!selectedProcessor) {
+    inputBody = executionDetail.inputBody;
+    outputBody = executionDetail.outputBody;
+  }
+
+  // Header display
+  const headerName = selectedProcessor ? selectedProcessor.processorType : 'Exchange';
+  const headerStatus = selectedProcessor ? selectedProcessor.status : executionDetail.status;
+  const headerId = selectedProcessor ? selectedProcessor.processorId : executionDetail.executionId;
+  const headerDuration = selectedProcessor ? selectedProcessor.durationMs : executionDetail.durationMs;
+
+  return (
+    <div className={styles.detailPanel}>
+      {/* Processor / Exchange header bar */}
+      <div className={styles.processorHeader}>
+        <span className={styles.processorName}>{headerName}</span>
+        <span className={`${styles.statusBadge} ${statusClass(headerStatus)}`}>
+          {headerStatus}
+        </span>
+        <span className={styles.processorId}>{headerId}</span>
+        <span className={styles.processorDuration}>{formatDuration(headerDuration)}</span>
+      </div>
+
+      {/* Tab bar */}
+      <div className={styles.tabBar}>
+        {TABS.map((tab) => {
+          const isActive = activeTab === tab.key;
+          const isDisabled = tab.key === 'config';
+          const isError = tab.key === 'error' && hasError;
+          const isErrorGrayed = tab.key === 'error' && !hasError;
+
+          let className = styles.tab;
+          if (isActive) className += ` ${styles.tabActive}`;
+          if (isDisabled) className += ` ${styles.tabDisabled}`;
+          if (isError && !isActive) className += ` ${styles.tabError}`;
+          if (isErrorGrayed && !isActive) className += ` ${styles.tabDisabled}`;
+
+          return (
+            <button
+              key={tab.key}
+              className={className}
+              onClick={() => {
+                if (!isDisabled) setActiveTab(tab.key);
+              }}
+              type="button"
+            >
+              {tab.label}
+            </button>
+          );
+        })}
+      </div>
+
+      {/* Tab content */}
+      <div className={styles.tabContent}>
+        {activeTab === 'info' && (
+          <InfoTab processor={selectedProcessor} executionDetail={executionDetail} />
+        )}
+        {activeTab === 'headers' && (
+          <HeadersTab
+            executionId={executionId}
+            processorId={selectedProcessor?.processorId ?? null}
+            exchangeInputHeaders={executionDetail.inputHeaders}
+            exchangeOutputHeaders={executionDetail.outputHeaders}
+          />
+        )}
+        {activeTab === 'input' && (
+          <BodyTab body={inputBody} label="Input" />
+        )}
+        {activeTab === 'output' && (
+          <BodyTab body={outputBody} label="Output" />
+        )}
+        {activeTab === 'error' && (
+          <ErrorTab processor={selectedProcessor} executionDetail={executionDetail} />
+        )}
+        {activeTab === 'config' && (
+          <ConfigTab />
+        )}
+        {activeTab === 'timeline' && (
+          <TimelineTab
+            executionDetail={executionDetail}
+            selectedProcessorId={selectedProcessor?.processorId ?? null}
+            onSelectProcessor={onSelectProcessor}
+          />
+        )}
+      </div>
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/ExecutionDiagram.module.css b/ui/src/components/ExecutionDiagram/ExecutionDiagram.module.css
new file mode 100644
index 00000000..dfd17468
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/ExecutionDiagram.module.css
@@ -0,0 +1,538 @@
+/* ==========================================================================
+   EXECUTION DIAGRAM — LAYOUT
+   ========================================================================== */
+.executionDiagram {
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  height: 100%;
+  min-height: 400px;
+  overflow: hidden;
+}
+
+.exchangeBar {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  padding: 8px 14px;
+  background: var(--bg-surface, #FFFFFF);
+  border-bottom: 1px solid var(--border, #E4DFD8);
+  font-size: 12px;
+  color: var(--text-secondary, #5C5347);
+  flex-shrink: 0;
+}
+
+.exchangeLabel {
+  font-weight: 600;
+  color: var(--text-primary, #1A1612);
+}
+
+.exchangeId {
+  font-size: 11px;
+  background: var(--bg-hover, #F5F0EA);
+  padding: 2px 6px;
+  border-radius: 3px;
+  color: var(--text-primary, #1A1612);
+}
+
+.exchangeMeta {
+  color: var(--text-muted, #9C9184);
+}
+
+.jumpToError {
+  margin-left: auto;
+  font-size: 10px;
+  padding: 3px 10px;
+  border: 1px solid var(--error, #C0392B);
+  background: #FDF2F0;
+  color: var(--error, #C0392B);
+  border-radius: 4px;
+  cursor: pointer;
+  font-weight: 500;
+  font-family: inherit;
+}
+
+.jumpToError:hover {
+  background: #F9E0DC;
+}
+
+.diagramArea {
+  overflow: hidden;
+  position: relative;
+}
+
+.splitter {
+  height: 4px;
+  background: var(--border, #E4DFD8);
+  cursor: row-resize;
+  flex-shrink: 0;
+}
+
+.splitter:hover {
+  background: var(--amber, #C6820E);
+}
+
+.detailArea {
+  overflow: hidden;
+  min-height: 120px;
+}
+
+.loadingState {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex: 1;
+  color: var(--text-muted, #9C9184);
+  font-size: 13px;
+}
+
+.errorState {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex: 1;
+  color: var(--error, #C0392B);
+  font-size: 13px;
+}
+
+.statusRunning {
+  color: var(--amber, #C6820E);
+  background: #FFF8F0;
+}
+
+/* ==========================================================================
+   DETAIL PANEL
+   ========================================================================== */
+.detailPanel {
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
+  background: var(--bg-surface, #FFFFFF);
+  border-top: 1px solid var(--border, #E4DFD8);
+}
+
+.processorHeader {
+  display: flex;
+  flex-direction: row;
+  align-items: center;
+  gap: 10px;
+  padding: 6px 14px;
+  border-bottom: 1px solid var(--border, #E4DFD8);
+  background: #FAFAF8;
+  min-height: 32px;
+}
+
+.processorName {
+  font-size: 12px;
+  font-weight: 600;
+  color: var(--text-primary, #1A1612);
+}
+
+.processorId {
+  font-size: 11px;
+  font-family: var(--font-mono, monospace);
+  color: var(--text-muted, #9C9184);
+}
+
+.processorDuration {
+  font-size: 11px;
+  font-family: var(--font-mono, monospace);
+  color: var(--text-secondary, #5C5347);
+  margin-left: auto;
+}
+
+/* ==========================================================================
+   STATUS BADGE
+   ========================================================================== */
+.statusBadge {
+  font-size: 10px;
+  font-weight: 600;
+  padding: 1px 6px;
+  border-radius: 8px;
+  text-transform: uppercase;
+  letter-spacing: 0.3px;
+}
+
+.statusCompleted {
+  color: var(--success, #3D7C47);
+  background: #F0F9F1;
+}
+
+.statusFailed {
+  color: var(--error, #C0392B);
+  background: #FDF2F0;
+}
+
+/* ==========================================================================
+   TAB BAR
+   ========================================================================== */
+.tabBar {
+  display: flex;
+  flex-direction: row;
+  border-bottom: 1px solid var(--border, #E4DFD8);
+  padding: 0 14px;
+  background: #FAFAF8;
+  gap: 0;
+}
+
+.tab {
+  padding: 6px 12px;
+  font-size: 11px;
+  font-family: var(--font-body, inherit);
+  cursor: pointer;
+  color: var(--text-muted, #9C9184);
+  border: none;
+  background: none;
+  border-bottom: 2px solid transparent;
+  transition: color 0.12s, border-color 0.12s;
+  white-space: nowrap;
+}
+
+.tab:hover {
+  color: var(--text-secondary, #5C5347);
+}
+
+.tabActive {
+  color: var(--amber, #C6820E);
+  border-bottom: 2px solid var(--amber, #C6820E);
+  font-weight: 600;
+}
+
+.tabDisabled {
+  opacity: 0.4;
+  cursor: default;
+}
+
+.tabDisabled:hover {
+  color: var(--text-muted, #9C9184);
+}
+
+.tabError {
+  color: var(--error, #C0392B);
+}
+
+.tabError:hover {
+  color: var(--error, #C0392B);
+}
+
+/* ==========================================================================
+   TAB CONTENT
+   ========================================================================== */
+.tabContent {
+  flex: 1;
+  overflow-y: auto;
+  padding: 10px 14px;
+}
+
+/* ==========================================================================
+   INFO TAB — GRID
+   ========================================================================== */
+.infoGrid {
+  display: grid;
+  grid-template-columns: 1fr 1fr 1fr;
+  gap: 12px 24px;
+}
+
+.fieldLabel {
+  font-size: 10px;
+  color: var(--text-muted, #9C9184);
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+  margin-bottom: 2px;
+}
+
+.fieldValue {
+  font-size: 12px;
+  color: var(--text-primary, #1A1612);
+  word-break: break-all;
+}
+
+.fieldValueMono {
+  font-size: 12px;
+  color: var(--text-primary, #1A1612);
+  font-family: var(--font-mono, monospace);
+  word-break: break-all;
+}
+
+/* ==========================================================================
+   ATTRIBUTE PILLS
+   ========================================================================== */
+.attributesSection {
+  margin-top: 14px;
+  padding-top: 10px;
+  border-top: 1px solid var(--border, #E4DFD8);
+}
+
+.attributesLabel {
+  font-size: 10px;
+  color: var(--text-muted, #9C9184);
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+  margin-bottom: 6px;
+}
+
+.attributesList {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 6px;
+}
+
+.attributePill {
+  font-size: 10px;
+  padding: 2px 8px;
+  background: var(--bg-hover, #F5F0EA);
+  border-radius: 10px;
+  color: var(--text-secondary, #5C5347);
+  font-family: var(--font-mono, monospace);
+}
+
+/* ==========================================================================
+   HEADERS TAB — SPLIT
+   ========================================================================== */
+.headersSplit {
+  display: flex;
+  gap: 0;
+  min-height: 0;
+  overflow-y: auto;
+  max-height: 100%;
+}
+
+.headersColumn {
+  flex: 1;
+  min-width: 0;
+}
+
+.headersColumn + .headersColumn {
+  border-left: 1px solid var(--border, #E4DFD8);
+  padding-left: 14px;
+  margin-left: 14px;
+}
+
+.headersColumnLabel {
+  font-size: 10px;
+  font-weight: 600;
+  color: var(--text-muted, #9C9184);
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+  margin-bottom: 6px;
+}
+
+.headersTable {
+  width: 100%;
+  font-size: 11px;
+  border-collapse: collapse;
+}
+
+.headersTable td {
+  padding: 3px 0;
+  border-bottom: 1px solid var(--border, #E4DFD8);
+  vertical-align: top;
+}
+
+.headersTable tr:last-child td {
+  border-bottom: none;
+}
+
+.headerKey {
+  font-family: var(--font-mono, monospace);
+  font-weight: 600;
+  color: var(--text-muted, #9C9184);
+  white-space: nowrap;
+  padding-right: 12px;
+  width: 140px;
+  max-width: 140px;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.headerVal {
+  font-family: var(--font-mono, monospace);
+  color: var(--text-primary, #1A1612);
+  word-break: break-all;
+}
+
+/* ==========================================================================
+   BODY / CODE TAB
+   ========================================================================== */
+.codeHeader {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-bottom: 8px;
+}
+
+.codeFormat {
+  font-size: 10px;
+  font-weight: 600;
+  color: var(--text-muted, #9C9184);
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+}
+
+.codeSize {
+  font-size: 10px;
+  color: var(--text-muted, #9C9184);
+  font-family: var(--font-mono, monospace);
+}
+
+.codeCopyBtn {
+  margin-left: auto;
+  font-size: 10px;
+  font-family: var(--font-body, inherit);
+  padding: 2px 8px;
+  border: 1px solid var(--border, #E4DFD8);
+  border-radius: 4px;
+  background: var(--bg-surface, #FFFFFF);
+  color: var(--text-secondary, #5C5347);
+  cursor: pointer;
+}
+
+.codeCopyBtn:hover {
+  background: var(--bg-hover, #F5F0EA);
+}
+
+.codeBlock {
+  background: #1A1612;
+  color: #E4DFD8;
+  padding: 12px;
+  border-radius: 6px;
+  font-family: var(--font-mono, monospace);
+  font-size: 11px;
+  line-height: 1.5;
+  overflow-x: auto;
+  white-space: pre-wrap;
+  word-break: break-all;
+  max-height: 400px;
+  overflow-y: auto;
+}
+
+/* ==========================================================================
+   ERROR TAB
+   ========================================================================== */
+.errorType {
+  font-size: 13px;
+  font-weight: 600;
+  color: var(--error, #C0392B);
+  margin-bottom: 8px;
+}
+
+.errorMessage {
+  font-size: 12px;
+  color: var(--text-primary, #1A1612);
+  background: #FDF2F0;
+  border: 1px solid #F5D5D0;
+  border-radius: 6px;
+  padding: 10px 12px;
+  margin-bottom: 12px;
+  line-height: 1.5;
+  word-break: break-word;
+}
+
+.errorStackTrace {
+  background: #1A1612;
+  color: #E4DFD8;
+  padding: 12px;
+  border-radius: 6px;
+  font-family: var(--font-mono, monospace);
+  font-size: 10px;
+  line-height: 1.5;
+  overflow-x: auto;
+  white-space: pre;
+  max-height: 300px;
+  overflow-y: auto;
+}
+
+.errorStackLabel {
+  font-size: 10px;
+  font-weight: 600;
+  color: var(--text-muted, #9C9184);
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+  margin-bottom: 6px;
+}
+
+/* ==========================================================================
+   TIMELINE / GANTT TAB
+   ========================================================================== */
+.ganttContainer {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+  overflow-y: auto;
+  max-height: 100%;
+}
+
+.ganttRow {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  cursor: pointer;
+  padding: 3px 4px;
+  border-radius: 3px;
+  transition: background 0.1s;
+}
+
+.ganttRow:hover {
+  background: var(--bg-hover, #F5F0EA);
+}
+
+.ganttSelected {
+  background: #FFF8F0;
+}
+
+.ganttSelected:hover {
+  background: #FFF8F0;
+}
+
+.ganttLabel {
+  width: 100px;
+  min-width: 100px;
+  font-size: 10px;
+  color: var(--text-secondary, #5C5347);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.ganttBar {
+  flex: 1;
+  height: 16px;
+  background: var(--bg-hover, #F5F0EA);
+  border-radius: 2px;
+  position: relative;
+  min-width: 0;
+}
+
+.ganttFill {
+  position: absolute;
+  height: 100%;
+  border-radius: 2px;
+  min-width: 2px;
+}
+
+.ganttFillCompleted {
+  background: var(--success, #3D7C47);
+}
+
+.ganttFillFailed {
+  background: var(--error, #C0392B);
+}
+
+.ganttDuration {
+  width: 50px;
+  min-width: 50px;
+  font-size: 10px;
+  font-family: var(--font-mono, monospace);
+  color: var(--text-muted, #9C9184);
+  text-align: right;
+}
+
+/* ==========================================================================
+   EMPTY STATE
+   ========================================================================== */
+.emptyState {
+  text-align: center;
+  color: var(--text-muted, #9C9184);
+  font-size: 12px;
+  padding: 20px;
+}
diff --git a/ui/src/components/ExecutionDiagram/ExecutionDiagram.tsx b/ui/src/components/ExecutionDiagram/ExecutionDiagram.tsx
new file mode 100644
index 00000000..fc5378c2
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/ExecutionDiagram.tsx
@@ -0,0 +1,215 @@
+import { useCallback, useRef, useState } from 'react';
+import type { NodeAction, NodeConfig } from '../ProcessDiagram/types';
+import type { ExecutionDetail, ProcessorNode } from './types';
+import { useExecutionDetail } from '../../api/queries/executions';
+import { useDiagramLayout } from '../../api/queries/diagrams';
+import { ProcessDiagram } from '../ProcessDiagram';
+import { DetailPanel } from './DetailPanel';
+import { useExecutionOverlay } from './useExecutionOverlay';
+import { useIterationState } from './useIterationState';
+import styles from './ExecutionDiagram.module.css';
+
+interface ExecutionDiagramProps {
+  executionId: string;
+  executionDetail?: ExecutionDetail;
+  direction?: 'LR' | 'TB';
+  knownRouteIds?: Set<string>;
+  onNodeAction?: (nodeId: string, action: NodeAction) => void;
+  nodeConfigs?: Map<string, NodeConfig>;
+  className?: string;
+}
+
+function findProcessorInTree(
+  nodes: ProcessorNode[] | undefined,
+  processorId: string | null,
+): ProcessorNode | null {
+  if (!nodes || !processorId) return null;
+  for (const n of nodes) {
+    if (n.processorId === processorId) return n;
+    if (n.children) {
+      const found = findProcessorInTree(n.children, processorId);
+      if (found) return found;
+    }
+  }
+  return null;
+}
+
+function findFailedProcessor(nodes: ProcessorNode[]): ProcessorNode | null {
+  for (const n of nodes) {
+    if (n.status === 'FAILED') return n;
+    if (n.children) {
+      const found = findFailedProcessor(n.children);
+      if (found) return found;
+    }
+  }
+  return null;
+}
+
+function statusBadgeClass(status: string): string {
+  const s = status?.toUpperCase();
+  if (s === 'COMPLETED') return `${styles.statusBadge} ${styles.statusCompleted}`;
+  if (s === 'FAILED') return `${styles.statusBadge} ${styles.statusFailed}`;
+  if (s === 'RUNNING') return `${styles.statusBadge} ${styles.statusRunning}`;
+  return styles.statusBadge;
+}
+
+export function ExecutionDiagram({
+  executionId,
+  executionDetail: externalDetail,
+  direction = 'LR',
+  knownRouteIds,
+  onNodeAction,
+  nodeConfigs,
+  className,
+}: ExecutionDiagramProps) {
+  // 1. Fetch execution data (skip if pre-fetched prop provided)
+  const detailQuery = useExecutionDetail(externalDetail ? null : executionId);
+  const detail = externalDetail ?? detailQuery.data;
+  const detailLoading = !externalDetail && detailQuery.isLoading;
+  const detailError = !externalDetail && detailQuery.error;
+
+  // 2. Load diagram by content hash
+  const diagramQuery = useDiagramLayout(detail?.diagramContentHash ?? null, direction);
+  const diagramLayout = diagramQuery.data;
+  const diagramLoading = diagramQuery.isLoading;
+  const diagramError = diagramQuery.error;
+
+  // 3. Initialize iteration state
+  const { iterationState, setIteration } = useIterationState(detail?.processors);
+
+  // 4. Compute overlay
+  const overlay = useExecutionOverlay(detail?.processors, iterationState);
+
+  // 5. Manage selection + center-on-node
+  const [selectedProcessorId, setSelectedProcessorId] = useState<string>('');
+  const [centerOnNodeId, setCenterOnNodeId] = useState<string>('');
+
+  // 6. Resizable splitter state
+  const [splitPercent, setSplitPercent] = useState(60);
+  const containerRef = useRef<HTMLDivElement>(null);
+
+  const handleSplitterDown = useCallback((e: React.PointerEvent) => {
+    e.currentTarget.setPointerCapture(e.pointerId);
+    const container = containerRef.current;
+    if (!container) return;
+    const onMove = (me: PointerEvent) => {
+      const rect = container.getBoundingClientRect();
+      const y = me.clientY - rect.top;
+      const pct = Math.min(85, Math.max(30, (y / rect.height) * 100));
+      setSplitPercent(pct);
+    };
+    const onUp = () => {
+      document.removeEventListener('pointermove', onMove);
+      document.removeEventListener('pointerup', onUp);
+    };
+    document.addEventListener('pointermove', onMove);
+    document.addEventListener('pointerup', onUp);
+  }, []);
+
+  // Jump to error: find first FAILED processor, select it, and center the viewport
+  const handleJumpToError = useCallback(() => {
+    if (!detail?.processors) return;
+    const failed = findFailedProcessor(detail.processors);
+    if (failed?.processorId) {
+      setSelectedProcessorId(failed.processorId);
+      // Use a unique value to re-trigger centering even if the same node
+      setCenterOnNodeId('');
+      requestAnimationFrame(() => setCenterOnNodeId(failed.processorId));
+    }
+  }, [detail?.processors]);
+
+  // Loading state
+  if (detailLoading || (detail && diagramLoading)) {
+    return (
+      <div className={`${styles.executionDiagram} ${className ?? ''}`}>
+        <div className={styles.loadingState}>Loading execution data...</div>
+      </div>
+    );
+  }
+
+  // Error state
+  if (detailError) {
+    return (
+      <div className={`${styles.executionDiagram} ${className ?? ''}`}>
+        <div className={styles.errorState}>Failed to load execution detail</div>
+      </div>
+    );
+  }
+
+  if (diagramError) {
+    return (
+      <div className={`${styles.executionDiagram} ${className ?? ''}`}>
+        <div className={styles.errorState}>Failed to load diagram</div>
+      </div>
+    );
+  }
+
+  if (!detail) {
+    return (
+      <div className={`${styles.executionDiagram} ${className ?? ''}`}>
+        <div className={styles.loadingState}>No execution data</div>
+      </div>
+    );
+  }
+
+  return (
+    <div ref={containerRef} className={`${styles.executionDiagram} ${className ?? ''}`}>
+      {/* Exchange summary bar */}
+      <div className={styles.exchangeBar}>
+        <span className={styles.exchangeLabel}>Exchange</span>
+        <code className={styles.exchangeId}>{detail.exchangeId || detail.executionId}</code>
+        <span className={statusBadgeClass(detail.status)}>
+          {detail.status}
+        </span>
+        <span className={styles.exchangeMeta}>
+          {detail.applicationName} / {detail.routeId}
+        </span>
+        <span className={styles.exchangeMeta}>{detail.durationMs}ms</span>
+        {detail.status === 'FAILED' && (
+          <button
+            className={styles.jumpToError}
+            onClick={handleJumpToError}
+            type="button"
+          >
+            Jump to Error
+          </button>
+        )}
+      </div>
+
+      {/* Diagram area */}
+      <div className={styles.diagramArea} style={{ height: `${splitPercent}%` }}>
+        <ProcessDiagram
+          application={detail.applicationName}
+          routeId={detail.routeId}
+          direction={direction}
+          diagramLayout={diagramLayout}
+          selectedNodeId={selectedProcessorId}
+          onNodeSelect={setSelectedProcessorId}
+          onNodeAction={onNodeAction}
+          nodeConfigs={nodeConfigs}
+          knownRouteIds={knownRouteIds}
+          executionOverlay={overlay}
+          iterationState={iterationState}
+          onIterationChange={setIteration}
+          centerOnNodeId={centerOnNodeId}
+        />
+      </div>
+
+      {/* Resizable splitter */}
+      <div
+        className={styles.splitter}
+        onPointerDown={handleSplitterDown}
+      />
+
+      {/* Detail panel */}
+      <div className={styles.detailArea} style={{ height: `${100 - splitPercent}%` }}>
+        <DetailPanel
+          selectedProcessor={findProcessorInTree(detail.processors, selectedProcessorId || null)}
+          executionDetail={detail}
+          executionId={executionId}
+          onSelectProcessor={setSelectedProcessorId}
+        />
+      </div>
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/index.ts b/ui/src/components/ExecutionDiagram/index.ts
new file mode 100644
index 00000000..45e339eb
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/index.ts
@@ -0,0 +1,2 @@
+export { ExecutionDiagram } from './ExecutionDiagram';
+export type { NodeExecutionState, IterationInfo, DetailTab } from './types';
diff --git a/ui/src/components/ExecutionDiagram/tabs/BodyTab.tsx b/ui/src/components/ExecutionDiagram/tabs/BodyTab.tsx
new file mode 100644
index 00000000..20eae893
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/tabs/BodyTab.tsx
@@ -0,0 +1,47 @@
+import { CodeBlock } from '@cameleer/design-system';
+import styles from '../ExecutionDiagram.module.css';
+
+interface BodyTabProps {
+  body: string | undefined;
+  label: string;
+}
+
+function detectLanguage(text: string): string {
+  const trimmed = text.trimStart();
+  if (trimmed.startsWith('{') || trimmed.startsWith('[')) {
+    try {
+      JSON.parse(text);
+      return 'json';
+    } catch {
+      // not valid JSON
+    }
+  }
+  if (trimmed.startsWith('<')) return 'xml';
+  return 'text';
+}
+
+function formatBody(text: string, language: string): string {
+  if (language === 'json') {
+    try {
+      return JSON.stringify(JSON.parse(text), null, 2);
+    } catch {
+      return text;
+    }
+  }
+  return text;
+}
+
+export function BodyTab({ body, label }: BodyTabProps) {
+  if (!body) {
+    return <div className={styles.emptyState}>No {label.toLowerCase()} body available</div>;
+  }
+
+  const language = detectLanguage(body);
+  const formatted = formatBody(body, language);
+
+  return (
+    <div>
+      <CodeBlock content={formatted} language={language} copyable />
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/tabs/ConfigTab.tsx b/ui/src/components/ExecutionDiagram/tabs/ConfigTab.tsx
new file mode 100644
index 00000000..da6cf21d
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/tabs/ConfigTab.tsx
@@ -0,0 +1,9 @@
+import styles from '../ExecutionDiagram.module.css';
+
+export function ConfigTab() {
+  return (
+    <div className={styles.emptyState}>
+      Processor configuration data is not yet available.
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/tabs/ErrorTab.tsx b/ui/src/components/ExecutionDiagram/tabs/ErrorTab.tsx
new file mode 100644
index 00000000..2a8630c9
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/tabs/ErrorTab.tsx
@@ -0,0 +1,46 @@
+import { CodeBlock } from '@cameleer/design-system';
+import type { ProcessorNode, ExecutionDetail } from '../types';
+import styles from '../ExecutionDiagram.module.css';
+
+interface ErrorTabProps {
+  processor: ProcessorNode | null;
+  executionDetail: ExecutionDetail;
+}
+
+function extractExceptionType(errorMessage: string): string {
+  const colonIdx = errorMessage.indexOf(':');
+  if (colonIdx > 0) {
+    return errorMessage.substring(0, colonIdx).trim();
+  }
+  return 'Error';
+}
+
+export function ErrorTab({ processor, executionDetail }: ErrorTabProps) {
+  const errorMessage = processor?.errorMessage || executionDetail.errorMessage;
+  const errorStackTrace = processor?.errorStackTrace || executionDetail.errorStackTrace;
+
+  if (!errorMessage) {
+    return (
+      <div className={styles.emptyState}>
+        {processor
+          ? 'No error on this processor'
+          : 'No error on this exchange'}
+      </div>
+    );
+  }
+
+  const exceptionType = extractExceptionType(errorMessage);
+
+  return (
+    <div>
+      <div className={styles.errorType}>{exceptionType}</div>
+      <div className={styles.errorMessage}>{errorMessage}</div>
+      {errorStackTrace && (
+        <>
+          <div className={styles.errorStackLabel}>Stack Trace</div>
+          <CodeBlock content={errorStackTrace} copyable />
+        </>
+      )}
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/tabs/HeadersTab.tsx b/ui/src/components/ExecutionDiagram/tabs/HeadersTab.tsx
new file mode 100644
index 00000000..762133b6
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/tabs/HeadersTab.tsx
@@ -0,0 +1,80 @@
+import { useProcessorSnapshotById } from '../../../api/queries/executions';
+import styles from '../ExecutionDiagram.module.css';
+
+interface HeadersTabProps {
+  executionId: string;
+  processorId: string | null;
+  exchangeInputHeaders?: string;
+  exchangeOutputHeaders?: string;
+}
+
+function parseHeaders(json: string | undefined): Record<string, string> {
+  if (!json) return {};
+  try {
+    return JSON.parse(json);
+  } catch {
+    return {};
+  }
+}
+
+function HeaderTable({ headers }: { headers: Record<string, string> }) {
+  const entries = Object.entries(headers);
+  if (entries.length === 0) {
+    return <div className={styles.emptyState}>No headers</div>;
+  }
+  return (
+    <table className={styles.headersTable}>
+      <tbody>
+        {entries.map(([k, v]) => (
+          <tr key={k}>
+            <td className={styles.headerKey}>{k}</td>
+            <td className={styles.headerVal}>{v}</td>
+          </tr>
+        ))}
+      </tbody>
+    </table>
+  );
+}
+
+export function HeadersTab({
+  executionId,
+  processorId,
+  exchangeInputHeaders,
+  exchangeOutputHeaders,
+}: HeadersTabProps) {
+  const snapshotQuery = useProcessorSnapshotById(
+    processorId ? executionId : null,
+    processorId,
+  );
+
+  let inputHeaders: Record<string, string>;
+  let outputHeaders: Record<string, string>;
+
+  if (processorId && snapshotQuery.data) {
+    inputHeaders = parseHeaders(snapshotQuery.data.inputHeaders);
+    outputHeaders = parseHeaders(snapshotQuery.data.outputHeaders);
+  } else if (!processorId) {
+    inputHeaders = parseHeaders(exchangeInputHeaders);
+    outputHeaders = parseHeaders(exchangeOutputHeaders);
+  } else {
+    inputHeaders = {};
+    outputHeaders = {};
+  }
+
+  if (processorId && snapshotQuery.isLoading) {
+    return <div className={styles.emptyState}>Loading headers...</div>;
+  }
+
+  return (
+    <div className={styles.headersSplit}>
+      <div className={styles.headersColumn}>
+        <div className={styles.headersColumnLabel}>Input Headers</div>
+        <HeaderTable headers={inputHeaders} />
+      </div>
+      <div className={styles.headersColumn}>
+        <div className={styles.headersColumnLabel}>Output Headers</div>
+        <HeaderTable headers={outputHeaders} />
+      </div>
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/tabs/InfoTab.tsx b/ui/src/components/ExecutionDiagram/tabs/InfoTab.tsx
new file mode 100644
index 00000000..65f59566
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/tabs/InfoTab.tsx
@@ -0,0 +1,115 @@
+import type { ProcessorNode, ExecutionDetail } from '../types';
+import styles from '../ExecutionDiagram.module.css';
+
+interface InfoTabProps {
+  processor: ProcessorNode | null;
+  executionDetail: ExecutionDetail;
+}
+
+function formatTime(iso: string | undefined): string {
+  if (!iso) return '-';
+  try {
+    const d = new Date(iso);
+    const h = String(d.getHours()).padStart(2, '0');
+    const m = String(d.getMinutes()).padStart(2, '0');
+    const s = String(d.getSeconds()).padStart(2, '0');
+    const ms = String(d.getMilliseconds()).padStart(3, '0');
+    return `${h}:${m}:${s}.${ms}`;
+  } catch {
+    return iso;
+  }
+}
+
+function formatDuration(ms: number | undefined): string {
+  if (ms === undefined || ms === null) return '-';
+  if (ms < 1000) return `${ms}ms`;
+  return `${(ms / 1000).toFixed(1)}s`;
+}
+
+function statusClass(status: string): string {
+  const s = status?.toUpperCase();
+  if (s === 'COMPLETED') return styles.statusCompleted;
+  if (s === 'FAILED') return styles.statusFailed;
+  return '';
+}
+
+function Field({ label, value, mono }: { label: string; value: string; mono?: boolean }) {
+  return (
+    <div>
+      <div className={styles.fieldLabel}>{label}</div>
+      <div className={mono ? styles.fieldValueMono : styles.fieldValue}>{value || '-'}</div>
+    </div>
+  );
+}
+
+function Attributes({ attrs }: { attrs: Record<string, string> | undefined }) {
+  if (!attrs) return null;
+  const entries = Object.entries(attrs);
+  if (entries.length === 0) return null;
+
+  return (
+    <div className={styles.attributesSection}>
+      <div className={styles.attributesLabel}>Attributes</div>
+      <div className={styles.attributesList}>
+        {entries.map(([k, v]) => (
+          <span key={k} className={styles.attributePill}>
+            {k}: {v}
+          </span>
+        ))}
+      </div>
+    </div>
+  );
+}
+
+export function InfoTab({ processor, executionDetail }: InfoTabProps) {
+  if (processor) {
+    return (
+      <div>
+        <div className={styles.infoGrid}>
+          <Field label="Processor ID" value={processor.processorId} mono />
+          <Field label="Type" value={processor.processorType} />
+          <div>
+            <div className={styles.fieldLabel}>Status</div>
+            <span className={`${styles.statusBadge} ${statusClass(processor.status)}`}>
+              {processor.status}
+            </span>
+          </div>
+
+          <Field label="Start Time" value={formatTime(processor.startTime)} mono />
+          <Field label="End Time" value={formatTime(processor.endTime)} mono />
+          <Field label="Duration" value={formatDuration(processor.durationMs)} mono />
+
+          <Field label="Endpoint URI" value={processor.processorType} />
+          <Field label="Resolved URI" value="-" />
+          <div />
+        </div>
+        <Attributes attrs={processor.attributes} />
+      </div>
+    );
+  }
+
+  // Exchange-level view
+  return (
+    <div>
+      <div className={styles.infoGrid}>
+        <Field label="Execution ID" value={executionDetail.executionId} mono />
+        <Field label="Correlation ID" value={executionDetail.correlationId} mono />
+        <Field label="Exchange ID" value={executionDetail.exchangeId} mono />
+
+        <Field label="Application" value={executionDetail.applicationName} />
+        <Field label="Route ID" value={executionDetail.routeId} />
+        <div>
+          <div className={styles.fieldLabel}>Status</div>
+          <span className={`${styles.statusBadge} ${statusClass(executionDetail.status)}`}>
+            {executionDetail.status}
+          </span>
+        </div>
+
+        <Field label="Start Time" value={formatTime(executionDetail.startTime)} mono />
+        <Field label="End Time" value={formatTime(executionDetail.endTime)} mono />
+        <Field label="Duration" value={formatDuration(executionDetail.durationMs)} mono />
+      </div>
+      <Attributes attrs={executionDetail.attributes} />
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/tabs/TimelineTab.tsx b/ui/src/components/ExecutionDiagram/tabs/TimelineTab.tsx
new file mode 100644
index 00000000..1438b9fb
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/tabs/TimelineTab.tsx
@@ -0,0 +1,94 @@
+import type { ExecutionDetail, ProcessorNode } from '../types';
+import styles from '../ExecutionDiagram.module.css';
+
+interface TimelineTabProps {
+  executionDetail: ExecutionDetail;
+  selectedProcessorId: string | null;
+  onSelectProcessor: (id: string) => void;
+}
+
+interface FlatProcessor {
+  processorId: string;
+  processorType: string;
+  status: string;
+  startTime: string;
+  durationMs: number;
+  depth: number;
+}
+
+function flattenProcessors(
+  nodes: ProcessorNode[],
+  depth: number,
+  result: FlatProcessor[],
+): void {
+  for (const node of nodes) {
+    const status = node.status?.toUpperCase();
+    if (status === 'COMPLETED' || status === 'FAILED') {
+      result.push({
+        processorId: node.processorId,
+        processorType: node.processorType,
+        status,
+        startTime: node.startTime,
+        durationMs: node.durationMs,
+        depth,
+      });
+    }
+    if (node.children && node.children.length > 0) {
+      flattenProcessors(node.children, depth + 1, result);
+    }
+  }
+}
+
+export function TimelineTab({
+  executionDetail,
+  selectedProcessorId,
+  onSelectProcessor,
+}: TimelineTabProps) {
+  const flat: FlatProcessor[] = [];
+  flattenProcessors(executionDetail.processors || [], 0, flat);
+
+  if (flat.length === 0) {
+    return <div className={styles.emptyState}>No processor timeline data available</div>;
+  }
+
+  const execStart = new Date(executionDetail.startTime).getTime();
+  const totalDuration = executionDetail.durationMs || 1;
+
+  return (
+    <div className={styles.ganttContainer}>
+      {flat.map((proc) => {
+        const procStart = new Date(proc.startTime).getTime();
+        const offsetPct = Math.max(0, ((procStart - execStart) / totalDuration) * 100);
+        const widthPct = Math.max(0.5, (proc.durationMs / totalDuration) * 100);
+        const isSelected = proc.processorId === selectedProcessorId;
+        const fillClass = proc.status === 'FAILED'
+          ? styles.ganttFillFailed
+          : styles.ganttFillCompleted;
+
+        return (
+          <div
+            key={proc.processorId}
+            className={`${styles.ganttRow} ${isSelected ? styles.ganttSelected : ''}`}
+            onClick={() => onSelectProcessor(proc.processorId)}
+          >
+            <div className={styles.ganttLabel} title={proc.processorType || proc.processorId}>
+              {'  '.repeat(proc.depth)}{proc.processorType || proc.processorId}
+            </div>
+            <div className={styles.ganttBar}>
+              <div
+                className={`${styles.ganttFill} ${fillClass}`}
+                style={{
+                  left: `${offsetPct}%`,
+                  width: `${Math.min(widthPct, 100 - offsetPct)}%`,
+                }}
+              />
+            </div>
+            <div className={styles.ganttDuration}>
+              {proc.durationMs}ms
+            </div>
+          </div>
+        );
+      })}
+    </div>
+  );
+}
diff --git a/ui/src/components/ExecutionDiagram/types.ts b/ui/src/components/ExecutionDiagram/types.ts
new file mode 100644
index 00000000..5837fbd3
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/types.ts
@@ -0,0 +1,24 @@
+import type { components } from '../../api/schema';
+
+export type ExecutionDetail = components['schemas']['ExecutionDetail'];
+export type ProcessorNode = components['schemas']['ProcessorNode'];
+
+export interface NodeExecutionState {
+  status: 'COMPLETED' | 'FAILED';
+  durationMs: number;
+  /** True if this node's target sub-route failed (DIRECT/SEDA) */
+  subRouteFailed?: boolean;
+  /** True if trace data is available for this processor */
+  hasTraceData?: boolean;
+}
+
+export interface IterationInfo {
+  /** Current iteration index (0-based) */
+  current: number;
+  /** Total number of iterations */
+  total: number;
+  /** Type of iteration (determines label) */
+  type: 'loop' | 'split' | 'multicast';
+}
+
+export type DetailTab = 'info' | 'headers' | 'input' | 'output' | 'error' | 'config' | 'timeline';
diff --git a/ui/src/components/ExecutionDiagram/useExecutionOverlay.ts b/ui/src/components/ExecutionDiagram/useExecutionOverlay.ts
new file mode 100644
index 00000000..21736e24
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/useExecutionOverlay.ts
@@ -0,0 +1,80 @@
+import { useMemo } from 'react';
+import type { NodeExecutionState, IterationInfo, ProcessorNode } from './types';
+
+/**
+ * Recursively walks the ProcessorNode tree and populates an overlay map
+ * keyed by processorId → NodeExecutionState.
+ *
+ * Handles iteration filtering: when a processor has a loop/split/multicast
+ * index, only include it if it matches the currently selected iteration
+ * for its parent compound node.
+ */
+function buildOverlay(
+  processors: ProcessorNode[],
+  overlay: Map<string, NodeExecutionState>,
+  iterationState: Map<string, IterationInfo>,
+  parentId?: string,
+): void {
+  for (const proc of processors) {
+    if (!proc.processorId || !proc.status) continue;
+    if (proc.status !== 'COMPLETED' && proc.status !== 'FAILED') continue;
+
+    // Iteration filtering: if this processor belongs to an iterated parent,
+    // only include it when the index matches the selected iteration.
+    if (parentId && iterationState.has(parentId)) {
+      const info = iterationState.get(parentId)!;
+      if (info.type === 'loop' && proc.loopIndex != null) {
+        if (proc.loopIndex !== info.current) {
+          // Still recurse into children so nested compounds are discovered,
+          // but skip adding this processor to the overlay.
+          continue;
+        }
+      }
+      if (info.type === 'split' && proc.splitIndex != null) {
+        if (proc.splitIndex !== info.current) {
+          continue;
+        }
+      }
+      if (info.type === 'multicast' && proc.multicastIndex != null) {
+        if (proc.multicastIndex !== info.current) {
+          continue;
+        }
+      }
+    }
+
+    const subRouteFailed =
+      proc.status === 'FAILED' &&
+      (proc.processorType?.includes('DIRECT') || proc.processorType?.includes('SEDA'));
+
+    overlay.set(proc.processorId, {
+      status: proc.status as 'COMPLETED' | 'FAILED',
+      durationMs: proc.durationMs ?? 0,
+      subRouteFailed: subRouteFailed || undefined,
+      hasTraceData: true,
+    });
+
+    // Recurse into children, passing this processor as the parent for iteration filtering.
+    if (proc.children?.length) {
+      buildOverlay(proc.children, overlay, iterationState, proc.processorId);
+    }
+  }
+}
+
+/**
+ * Maps execution data (processor tree) to diagram overlay state.
+ *
+ * Returns a Map<processorId, NodeExecutionState> that tells DiagramNode
+ * and DiagramEdge how to render each element (success/failure colors,
+ * traversed edges, etc.).
+ */
+export function useExecutionOverlay(
+  processors: ProcessorNode[] | undefined,
+  iterationState: Map<string, IterationInfo>,
+): Map<string, NodeExecutionState> {
+  return useMemo(() => {
+    if (!processors) return new Map();
+    const overlay = new Map<string, NodeExecutionState>();
+    buildOverlay(processors, overlay, iterationState);
+    return overlay;
+  }, [processors, iterationState]);
+}
diff --git a/ui/src/components/ExecutionDiagram/useIterationState.ts b/ui/src/components/ExecutionDiagram/useIterationState.ts
new file mode 100644
index 00000000..02a61c04
--- /dev/null
+++ b/ui/src/components/ExecutionDiagram/useIterationState.ts
@@ -0,0 +1,91 @@
+import { useCallback, useEffect, useState } from 'react';
+import type { IterationInfo, ProcessorNode } from './types';
+
+/**
+ * Walks the processor tree and detects compound nodes that have iterated
+ * children (loop, split, multicast). Populates a map of compoundId →
+ * IterationInfo so the UI can show stepper widgets and filter iterations.
+ */
+function detectIterations(
+  processors: ProcessorNode[],
+  result: Map<string, IterationInfo>,
+): void {
+  for (const proc of processors) {
+    if (!proc.children?.length) continue;
+
+    // Check if children indicate a loop compound
+    const loopChild = proc.children.find(
+      (c) => c.loopSize != null && c.loopSize > 0,
+    );
+    if (loopChild && proc.processorId) {
+      result.set(proc.processorId, {
+        current: 0,
+        total: loopChild.loopSize!,
+        type: 'loop',
+      });
+    }
+
+    // Check if children indicate a split compound
+    const splitChild = proc.children.find(
+      (c) => c.splitSize != null && c.splitSize > 0,
+    );
+    if (splitChild && !loopChild && proc.processorId) {
+      result.set(proc.processorId, {
+        current: 0,
+        total: splitChild.splitSize!,
+        type: 'split',
+      });
+    }
+
+    // Check if children indicate a multicast compound
+    if (!loopChild && !splitChild) {
+      const multicastIndices = new Set<number>();
+      for (const child of proc.children) {
+        if (child.multicastIndex != null) {
+          multicastIndices.add(child.multicastIndex);
+        }
+      }
+      if (multicastIndices.size > 0 && proc.processorId) {
+        result.set(proc.processorId, {
+          current: 0,
+          total: multicastIndices.size,
+          type: 'multicast',
+        });
+      }
+    }
+
+    // Recurse into children to find nested iterations
+    detectIterations(proc.children, result);
+  }
+}
+
+/**
+ * Manages per-compound iteration state for the execution overlay.
+ *
+ * Scans the processor tree to detect compounds with iterated children
+ * and tracks which iteration index is currently selected for each.
+ */
+export function useIterationState(processors: ProcessorNode[] | undefined) {
+  const [state, setState] = useState<Map<string, IterationInfo>>(new Map());
+
+  // Initialize iteration info when processors change
+  useEffect(() => {
+    if (!processors) return;
+    const newState = new Map<string, IterationInfo>();
+    detectIterations(processors, newState);
+    setState(newState);
+  }, [processors]);
+
+  const setIteration = useCallback((compoundId: string, index: number) => {
+    setState((prev) => {
+      const next = new Map(prev);
+      const info = next.get(compoundId);
+      if (info && index >= 0 && index < info.total) {
+        next.set(compoundId, { ...info, current: index });
+      }
+      return next;
+    });
+  }, []);
+
+  return { iterationState: state, setIteration };
+}
diff --git a/ui/src/components/ProcessDiagram/CompoundNode.tsx b/ui/src/components/ProcessDiagram/CompoundNode.tsx
index eb5f7c33..2692a2bf 100644
--- a/ui/src/components/ProcessDiagram/CompoundNode.tsx
+++ b/ui/src/components/ProcessDiagram/CompoundNode.tsx
@@ -1,8 +1,10 @@
 import type { DiagramNode as DiagramNodeType, DiagramEdge as DiagramEdgeType } from '../../api/queries/diagrams';
 import type { NodeConfig } from './types';
+import type { NodeExecutionState, IterationInfo } from '../ExecutionDiagram/types';
 import { colorForType, isCompoundType } from './node-colors';
 import { DiagramNode } from './DiagramNode';
 import { DiagramEdge } from './DiagramEdge';
+import styles from './ProcessDiagram.module.css';
 
 const HEADER_HEIGHT = 22;
 const CORNER_RADIUS = 4;
@@ -17,6 +19,14 @@ interface CompoundNodeProps {
   selectedNodeId?: string;
   hoveredNodeId: string | null;
   nodeConfigs?: Map<string, NodeConfig>;
+  /** Execution overlay for edge traversal coloring */
+  executionOverlay?: Map<string, NodeExecutionState>;
+  /** Whether an execution overlay is active (enables dimming of skipped nodes) */
+  overlayActive?: boolean;
+  /** Per-compound iteration state */
+  iterationState?: Map<string, IterationInfo>;
+  /** Called when user changes iteration on a compound stepper */
+  onIterationChange?: (compoundNodeId: string, iterationIndex: number) => void;
   onNodeClick: (nodeId: string) => void;
   onNodeDoubleClick?: (nodeId: string) => void;
   onNodeEnter: (nodeId: string) => void;
@@ -25,7 +35,8 @@ interface CompoundNodeProps {
 
 export function CompoundNode({
   node, edges, parentX = 0, parentY = 0,
-  selectedNodeId, hoveredNodeId, nodeConfigs,
+  selectedNodeId, hoveredNodeId, nodeConfigs, executionOverlay,
+  overlayActive, iterationState, onIterationChange,
   onNodeClick, onNodeDoubleClick, onNodeEnter, onNodeLeave,
 }: CompoundNodeProps) {
   const x = (node.x ?? 0) - parentX;
@@ -37,6 +48,8 @@ export function CompoundNode({
   const color = colorForType(node.type);
   const typeName = node.type?.replace(/^EIP_/, '').replace(/_/g, ' ') ?? '';
   const label = node.label ? `${typeName}: ${node.label}` : typeName;
+  const iterationInfo = node.id ? iterationState?.get(node.id) : undefined;
+  const headerWidth = w;
 
   // Collect all descendant node IDs to filter edges that belong inside this compound
   const descendantIds = new Set<string>();
@@ -76,17 +89,44 @@ export function CompoundNode({
         {label}
       </text>
 
+      {/* Iteration stepper (for LOOP, SPLIT, MULTICAST with overlay data) */}
+      {iterationInfo && (
+        <foreignObject x={headerWidth - 80} y={1} width={75} height={20}>
+          <div className={styles.iterationStepper}>
+            <button
+              onClick={(e) => { e.stopPropagation(); onIterationChange?.(node.id!, iterationInfo.current - 1); }}
+              disabled={iterationInfo.current <= 0}
+            >
+              &lsaquo;
+            </button>
+            <span>{iterationInfo.current + 1} / {iterationInfo.total}</span>
+            <button
+              onClick={(e) => { e.stopPropagation(); onIterationChange?.(node.id!, iterationInfo.current + 1); }}
+              disabled={iterationInfo.current >= iterationInfo.total - 1}
+            >
+              &rsaquo;
+            </button>
+          </div>
+        </foreignObject>
+      )}
+
       {/* Internal edges (rendered after background, before children) */}
       <g className="edges">
-        {internalEdges.map((edge, i) => (
-          <DiagramEdge
-            key={`${edge.sourceId}-${edge.targetId}-${i}`}
-            edge={{
-              ...edge,
-              points: edge.points.map(p => [p[0] - absX, p[1] - absY]),
-            }}
-          />
-        ))}
+        {internalEdges.map((edge, i) => {
+          const isTraversed = executionOverlay
+            ? (executionOverlay.has(edge.sourceId) && executionOverlay.has(edge.targetId))
+            : undefined;
+          return (
+            <DiagramEdge
+              key={`${edge.sourceId}-${edge.targetId}-${i}`}
+              edge={{
+                ...edge,
+                points: edge.points.map(p => [p[0] - absX, p[1] - absY]),
+              }}
+              traversed={isTraversed}
+            />
+          );
+        })}
       </g>
 
       {/* Children — recurse into compound children, render leaves as DiagramNode */}
@@ -102,6 +142,10 @@ export function CompoundNode({
               selectedNodeId={selectedNodeId}
               hoveredNodeId={hoveredNodeId}
               nodeConfigs={nodeConfigs}
+              executionOverlay={executionOverlay}
+              overlayActive={overlayActive}
+              iterationState={iterationState}
+              onIterationChange={onIterationChange}
               onNodeClick={onNodeClick}
               onNodeDoubleClick={onNodeDoubleClick}
               onNodeEnter={onNodeEnter}
@@ -120,6 +164,8 @@ export function CompoundNode({
             isHovered={hoveredNodeId === child.id}
             isSelected={selectedNodeId === child.id}
             config={child.id ? nodeConfigs?.get(child.id) : undefined}
+            executionState={executionOverlay?.get(child.id ?? '')}
+            overlayActive={overlayActive}
             onClick={() => child.id && onNodeClick(child.id)}
             onDoubleClick={() => child.id && onNodeDoubleClick?.(child.id)}
             onMouseEnter={() => child.id && onNodeEnter(child.id)}
diff --git a/ui/src/components/ProcessDiagram/DiagramEdge.tsx b/ui/src/components/ProcessDiagram/DiagramEdge.tsx
index 7c6c5a9c..3b0a8b41 100644
--- a/ui/src/components/ProcessDiagram/DiagramEdge.tsx
+++ b/ui/src/components/ProcessDiagram/DiagramEdge.tsx
@@ -3,9 +3,11 @@ import type { DiagramEdge as DiagramEdgeType } from '../../api/queries/diagrams'
 interface DiagramEdgeProps {
   edge: DiagramEdgeType;
   offsetY?: number;
+  /** undefined = no overlay (default gray solid), true = traversed (green solid), false = not traversed (gray dashed) */
+  traversed?: boolean | undefined;
 }
 
-export function DiagramEdge({ edge, offsetY = 0 }: DiagramEdgeProps) {
+export function DiagramEdge({ edge, offsetY = 0, traversed }: DiagramEdgeProps) {
   const pts = edge.points;
   if (!pts || pts.length < 2) return null;
 
@@ -29,9 +31,10 @@ export function DiagramEdge({ edge, offsetY = 0 }: DiagramEdgeProps) {
       <path
         d={d}
         fill="none"
-        stroke="#9CA3AF"
-        strokeWidth={1.5}
-        markerEnd="url(#arrowhead)"
+        stroke={traversed === true ? '#3D7C47' : '#9CA3AF'}
+        strokeWidth={traversed === true ? 1.5 : traversed === false ? 1 : 1.5}
+        strokeDasharray={traversed === false ? '4,3' : undefined}
+        markerEnd={traversed === true ? 'url(#arrowhead-green)' : traversed === false ? undefined : 'url(#arrowhead)'}
       />
       {edge.label && pts.length >= 2 && (
         <text
diff --git a/ui/src/components/ProcessDiagram/DiagramNode.tsx b/ui/src/components/ProcessDiagram/DiagramNode.tsx
index 1fd03d92..e4efe737 100644
--- a/ui/src/components/ProcessDiagram/DiagramNode.tsx
+++ b/ui/src/components/ProcessDiagram/DiagramNode.tsx
@@ -1,5 +1,6 @@
 import type { DiagramNode as DiagramNodeType } from '../../api/queries/diagrams';
 import type { NodeConfig } from './types';
+import type { NodeExecutionState } from '../ExecutionDiagram/types';
 import { colorForType, iconForType } from './node-colors';
 import { ConfigBadge } from './ConfigBadge';
 
@@ -11,14 +12,23 @@ interface DiagramNodeProps {
   isHovered: boolean;
   isSelected: boolean;
   config?: NodeConfig;
+  executionState?: NodeExecutionState;
+  overlayActive?: boolean;
   onClick: () => void;
   onDoubleClick?: () => void;
   onMouseEnter: () => void;
   onMouseLeave: () => void;
 }
 
+function formatDuration(ms: number): string {
+  if (ms < 1000) return `${ms}ms`;
+  return `${(ms / 1000).toFixed(1)}s`;
+}
+
 export function DiagramNode({
-  node, isHovered, isSelected, config, onClick, onDoubleClick, onMouseEnter, onMouseLeave,
+  node, isHovered, isSelected, config,
+  executionState, overlayActive,
+  onClick, onDoubleClick, onMouseEnter, onMouseLeave,
 }: DiagramNodeProps) {
   const x = node.x ?? 0;
   const y = node.y ?? 0;
@@ -31,6 +41,33 @@ export function DiagramNode({
   const typeName = node.type?.replace(/^EIP_/, '').replace(/_/g, ' ') ?? '';
   const detail = node.label || '';
 
+  // Overlay state derivation
+  const isCompleted = executionState?.status === 'COMPLETED';
+  const isFailed = executionState?.status === 'FAILED';
+  const isSkipped = overlayActive && !executionState;
+
+  // Colors based on execution state
+  let cardFill = isHovered ? '#F5F0EA' : 'white';
+  let borderStroke = isHovered || isSelected ? color : '#E4DFD8';
+  let borderWidth = isHovered || isSelected ? 1.5 : 1;
+  let topBarColor = color;
+  let labelColor = '#1A1612';
+
+  if (isCompleted) {
+    cardFill = isHovered ? '#E4F5E6' : '#F0F9F1';
+    borderStroke = '#3D7C47';
+    borderWidth = 1.5;
+    topBarColor = '#3D7C47';
+  } else if (isFailed) {
+    cardFill = isHovered ? '#F9E4E1' : '#FDF2F0';
+    borderStroke = '#C0392B';
+    borderWidth = 2;
+    topBarColor = '#C0392B';
+    labelColor = '#C0392B';
+  }
+
+  const statusColor = isCompleted ? '#3D7C47' : isFailed ? '#C0392B' : undefined;
+
   return (
     <g
       data-node-id={node.id}
@@ -40,6 +77,7 @@ export function DiagramNode({
       onMouseEnter={onMouseEnter}
       onMouseLeave={onMouseLeave}
       style={{ cursor: 'pointer' }}
+      opacity={isSkipped ? 0.35 : undefined}
     >
       {/* Selection ring */}
       {isSelected && (
@@ -62,34 +100,93 @@ export function DiagramNode({
         width={w}
         height={h}
         rx={CORNER_RADIUS}
-        fill={isHovered ? '#F5F0EA' : 'white'}
-        stroke={isHovered || isSelected ? color : '#E4DFD8'}
-        strokeWidth={isHovered || isSelected ? 1.5 : 1}
+        fill={cardFill}
+        stroke={borderStroke}
+        strokeWidth={borderWidth}
       />
 
       {/* Colored top bar */}
-      <rect x={0} y={0} width={w} height={TOP_BAR_HEIGHT} rx={CORNER_RADIUS} fill={color} />
-      <rect x={CORNER_RADIUS} y={0} width={w - CORNER_RADIUS * 2} height={TOP_BAR_HEIGHT} fill={color} />
+      <rect x={0} y={0} width={w} height={TOP_BAR_HEIGHT} rx={CORNER_RADIUS} fill={topBarColor} />
+      <rect x={CORNER_RADIUS} y={0} width={w - CORNER_RADIUS * 2} height={TOP_BAR_HEIGHT} fill={topBarColor} />
 
       {/* Icon */}
-      <text x={14} y={h / 2 + 6} fill={color} fontSize={14}>
+      <text x={14} y={h / 2 + 6} fill={statusColor ?? color} fontSize={14}>
         {icon}
       </text>
 
       {/* Type name */}
-      <text x={32} y={h / 2 + 1} fill="#1A1612" fontSize={11} fontWeight={600}>
+      <text x={32} y={h / 2 + 1} fill={labelColor} fontSize={11} fontWeight={600}>
         {typeName}
       </text>
 
       {/* Detail label (truncated) */}
       {detail && detail !== typeName && (
-        <text x={32} y={h / 2 + 14} fill="#5C5347" fontSize={10}>
+        <text x={32} y={h / 2 + 14} fill={isFailed ? '#C0392B' : '#5C5347'} fontSize={10}>
           {detail.length > 22 ? detail.slice(0, 20) + '...' : detail}
         </text>
       )}
 
       {/* Config badges */}
       {config && <ConfigBadge nodeWidth={w} config={config} />}
+
+      {/* Execution overlay: status badge inside card, top-right corner */}
+      {isCompleted && (
+        <>
+          <circle cx={w - 10} cy={TOP_BAR_HEIGHT + 8} r={6} fill="#3D7C47" />
+          <text
+            x={w - 10}
+            y={TOP_BAR_HEIGHT + 11}
+            textAnchor="middle"
+            fill="white"
+            fontSize={9}
+            fontWeight={700}
+          >
+            &#x2713;
+          </text>
+        </>
+      )}
+      {isFailed && (
+        <>
+          <circle cx={w - 10} cy={TOP_BAR_HEIGHT + 8} r={6} fill="#C0392B" />
+          <text
+            x={w - 10}
+            y={TOP_BAR_HEIGHT + 11}
+            textAnchor="middle"
+            fill="white"
+            fontSize={9}
+            fontWeight={700}
+          >
+            !
+          </text>
+        </>
+      )}
+
+      {/* Execution overlay: duration text at bottom-right */}
+      {executionState && statusColor && (
+        <text
+          x={w - 6}
+          y={h - 4}
+          textAnchor="end"
+          fill={statusColor}
+          fontSize={9}
+          fontWeight={500}
+        >
+          {formatDuration(executionState.durationMs)}
+        </text>
+      )}
+
+      {/* Sub-route failure: drill-down arrow at bottom-left */}
+      {isFailed && executionState?.subRouteFailed && (
+        <text
+          x={6}
+          y={h - 4}
+          fill="#C0392B"
+          fontSize={11}
+          fontWeight={700}
+        >
+          &#x21B3;
+        </text>
+      )}
     </g>
   );
 }
diff --git a/ui/src/components/ProcessDiagram/ErrorSection.tsx b/ui/src/components/ProcessDiagram/ErrorSection.tsx
index 0ca067ff..2ed3200a 100644
--- a/ui/src/components/ProcessDiagram/ErrorSection.tsx
+++ b/ui/src/components/ProcessDiagram/ErrorSection.tsx
@@ -1,6 +1,7 @@
 import { useMemo } from 'react';
 import type { DiagramSection } from './types';
 import type { NodeConfig } from './types';
+import type { NodeExecutionState, IterationInfo } from '../ExecutionDiagram/types';
 import type { DiagramNode as DiagramNodeType } from '../../api/queries/diagrams';
 import { DiagramEdge } from './DiagramEdge';
 import { DiagramNode } from './DiagramNode';
@@ -16,6 +17,14 @@ interface ErrorSectionProps {
   selectedNodeId?: string;
   hoveredNodeId: string | null;
   nodeConfigs?: Map<string, NodeConfig>;
+  /** Execution overlay for edge traversal coloring */
+  executionOverlay?: Map<string, NodeExecutionState>;
+  /** Whether an execution overlay is active (enables dimming of skipped nodes) */
+  overlayActive?: boolean;
+  /** Per-compound iteration state */
+  iterationState?: Map<string, IterationInfo>;
+  /** Called when user changes iteration on a compound stepper */
+  onIterationChange?: (compoundNodeId: string, iterationIndex: number) => void;
   onNodeClick: (nodeId: string) => void;
   onNodeDoubleClick?: (nodeId: string) => void;
   onNodeEnter: (nodeId: string) => void;
@@ -28,10 +37,25 @@ const VARIANT_COLORS: Record<string, string> = {
 };
 
 export function ErrorSection({
-  section, totalWidth, selectedNodeId, hoveredNodeId, nodeConfigs,
+  section, totalWidth, selectedNodeId, hoveredNodeId, nodeConfigs, executionOverlay,
+  overlayActive, iterationState, onIterationChange,
   onNodeClick, onNodeDoubleClick, onNodeEnter, onNodeLeave,
 }: ErrorSectionProps) {
   const color = VARIANT_COLORS[section.variant ?? 'error'] ?? VARIANT_COLORS.error;
+
+  // Check if any node in this section was executed (has overlay entry)
+  const wasTriggered = useMemo(() => {
+    if (!executionOverlay || executionOverlay.size === 0) return false;
+    function checkNodes(nodes: DiagramNodeType[]): boolean {
+      for (const n of nodes) {
+        if (n.id && executionOverlay!.has(n.id)) return true;
+        if (n.children && checkNodes(n.children)) return true;
+      }
+      return false;
+    }
+    return checkNodes(section.nodes);
+  }, [executionOverlay, section.nodes]);
+
   const boxHeight = useMemo(() => {
     let maxY = 0;
     for (const n of section.nodes) {
@@ -55,36 +79,54 @@ export function ErrorSection({
         {section.label}
       </text>
 
-      {/* Divider line */}
+      {/* Divider line — solid when triggered */}
       <line
         x1={0}
         y1={0}
         x2={totalWidth}
         y2={0}
         stroke={color}
-        strokeWidth={1}
-        strokeDasharray="6 3"
-        opacity={0.5}
+        strokeWidth={wasTriggered ? 1.5 : 1}
+        strokeDasharray={wasTriggered ? undefined : '6 3'}
+        opacity={wasTriggered ? 0.8 : 0.5}
       />
 
-      {/* Subtle red tint background — sized to actual content */}
+      {/* Background — stronger when this handler was triggered during execution */}
       <rect
         x={0}
         y={4}
         width={totalWidth}
         height={boxHeight}
         fill={color}
-        opacity={0.03}
+        opacity={wasTriggered ? 0.08 : 0.03}
         rx={4}
       />
+      {wasTriggered && (
+        <rect
+          x={0}
+          y={4}
+          width={totalWidth}
+          height={boxHeight}
+          fill="none"
+          stroke={color}
+          strokeWidth={1.5}
+          rx={4}
+          opacity={0.5}
+        />
+      )}
 
       {/* Content group with margin from top-left */}
       <g transform={`translate(${CONTENT_PADDING_LEFT}, ${CONTENT_PADDING_Y})`}>
         {/* Edges */}
         <g className="edges">
-          {section.edges.map((edge, i) => (
-            <DiagramEdge key={`${edge.sourceId}-${edge.targetId}-${i}`} edge={edge} />
-          ))}
+          {section.edges.map((edge, i) => {
+            const isTraversed = executionOverlay
+              ? (executionOverlay.has(edge.sourceId) && executionOverlay.has(edge.targetId))
+              : undefined;
+            return (
+              <DiagramEdge key={`${edge.sourceId}-${edge.targetId}-${i}`} edge={edge} traversed={isTraversed} />
+            );
+          })}
         </g>
 
         {/* Nodes */}
@@ -99,6 +141,10 @@ export function ErrorSection({
                   selectedNodeId={selectedNodeId}
                   hoveredNodeId={hoveredNodeId}
                   nodeConfigs={nodeConfigs}
+                  executionOverlay={executionOverlay}
+                  overlayActive={overlayActive}
+                  iterationState={iterationState}
+                  onIterationChange={onIterationChange}
                   onNodeClick={onNodeClick}
                   onNodeDoubleClick={onNodeDoubleClick}
                   onNodeEnter={onNodeEnter}
@@ -113,6 +159,8 @@ export function ErrorSection({
                 isHovered={hoveredNodeId === node.id}
                 isSelected={selectedNodeId === node.id}
                 config={node.id ? nodeConfigs?.get(node.id) : undefined}
+                executionState={executionOverlay?.get(node.id ?? '')}
+                overlayActive={overlayActive}
                 onClick={() => node.id && onNodeClick(node.id)}
                 onDoubleClick={() => node.id && onNodeDoubleClick?.(node.id)}
                 onMouseEnter={() => node.id && onNodeEnter(node.id)}
diff --git a/ui/src/components/ProcessDiagram/ProcessDiagram.module.css b/ui/src/components/ProcessDiagram/ProcessDiagram.module.css
index c61cd5ad..c70667c0 100644
--- a/ui/src/components/ProcessDiagram/ProcessDiagram.module.css
+++ b/ui/src/components/ProcessDiagram/ProcessDiagram.module.css
@@ -168,3 +168,36 @@
   background: var(--bg-hover, #F5F0EA);
   color: var(--text-primary, #1A1612);
 }
+
+.iterationStepper {
+  display: flex;
+  align-items: center;
+  gap: 2px;
+  background: rgba(255, 255, 255, 0.15);
+  border-radius: 3px;
+  padding: 1px 3px;
+  font-size: 10px;
+  color: white;
+  font-family: inherit;
+}
+
+.iterationStepper button {
+  width: 16px;
+  height: 16px;
+  border: none;
+  background: rgba(255, 255, 255, 0.2);
+  color: white;
+  border-radius: 2px;
+  cursor: pointer;
+  font-size: 10px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0;
+  font-family: inherit;
+}
+
+.iterationStepper button:disabled {
+  opacity: 0.3;
+  cursor: default;
+}
diff --git a/ui/src/components/ProcessDiagram/ProcessDiagram.tsx b/ui/src/components/ProcessDiagram/ProcessDiagram.tsx
index 7269c262..382c22fb 100644
--- a/ui/src/components/ProcessDiagram/ProcessDiagram.tsx
+++ b/ui/src/components/ProcessDiagram/ProcessDiagram.tsx
@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useState } from 'react';
+import { useCallback, useEffect, useMemo, useState } from 'react';
 import type { ProcessDiagramProps } from './types';
 import type { DiagramNode as DiagramNodeType } from '../../api/queries/diagrams';
 import { useDiagramData } from './useDiagramData';
@@ -52,6 +52,11 @@ export function ProcessDiagram({
   nodeConfigs,
   knownRouteIds,
   className,
+  diagramLayout,
+  executionOverlay,
+  iterationState,
+  onIterationChange,
+  centerOnNodeId,
 }: ProcessDiagramProps) {
   // Route stack for drill-down navigation
   const [routeStack, setRouteStack] = useState<string[]>([routeId]);
@@ -62,11 +67,33 @@ export function ProcessDiagram({
   }, [routeId]);
 
   const currentRouteId = routeStack[routeStack.length - 1];
+  const isDrilledDown = currentRouteId !== routeId;
+
+  // Disable overlay when drilled down — the execution data is for the root route
+  // and doesn't map to sub-route node IDs. Sub-route shows topology only.
+  const overlayActive = !!executionOverlay && !isDrilledDown;
+  const effectiveOverlay = isDrilledDown ? undefined : executionOverlay;
+
+  // Only use the pre-fetched diagramLayout for the root route.
+  const effectiveLayout = isDrilledDown ? undefined : diagramLayout;
 
   const { sections, totalWidth, totalHeight, isLoading, error } = useDiagramData(
-    application, currentRouteId, direction,
+    application, currentRouteId, direction, effectiveLayout,
   );
 
+  // Collect ENDPOINT node IDs — these are always "traversed" when overlay is active
+  // because the endpoint is the route entry point (not in the processor execution tree).
+  const endpointNodeIds = useMemo(() => {
+    const ids = new Set<string>();
+    if (!overlayActive || !sections.length) return ids;
+    for (const section of sections) {
+      for (const node of section.nodes) {
+        if (node.type === 'ENDPOINT' && node.id) ids.add(node.id);
+      }
+    }
+    return ids;
+  }, [overlayActive, sections]);
+
   const zoom = useZoomPan();
   const toolbar = useToolbarHover();
 
@@ -80,6 +107,50 @@ export function ProcessDiagram({
     }
   }, [totalWidth, totalHeight, currentRouteId]); // eslint-disable-line react-hooks/exhaustive-deps
 
+  // Center on a specific node when centerOnNodeId changes
+  useEffect(() => {
+    if (!centerOnNodeId || sections.length === 0) return;
+    const node = findNodeById(sections, centerOnNodeId);
+    if (!node) return;
+    const container = zoom.containerRef.current;
+    if (!container) return;
+    // Compute the node center in diagram coordinates
+    const nodeX = (node.x ?? 0) + (node.width ?? 160) / 2;
+    const nodeY = (node.y ?? 0) + (node.height ?? 40) / 2;
+    // Find which section the node is in to add its offsetY
+    let sectionOffsetY = 0;
+    for (const section of sections) {
+      const found = findNodeInSection(section.nodes, centerOnNodeId);
+      if (found) { sectionOffsetY = section.offsetY; break; }
+    }
+    const adjustedY = nodeY + sectionOffsetY;
+    // Pan so the node center is at the viewport center
+    const cw = container.clientWidth;
+    const ch = container.clientHeight;
+    const scale = zoom.state.scale;
+    zoom.panTo(
+      cw / 2 - nodeX * scale,
+      ch / 2 - adjustedY * scale,
+    );
+  }, [centerOnNodeId]); // eslint-disable-line react-hooks/exhaustive-deps
+
+  // Resolve execution state for a node. ENDPOINT nodes (the route's "from:")
+  // don't appear in the processor execution tree, but should be marked as
+  // COMPLETED when the route executed (i.e., overlay has any entries).
+  const getNodeExecutionState = useCallback(
+    (nodeId: string | undefined, nodeType: string | undefined) => {
+      if (!nodeId || !effectiveOverlay) return undefined;
+      const state = effectiveOverlay.get(nodeId);
+      if (state) return state;
+      // Synthesize COMPLETED for ENDPOINT nodes when overlay is active
+      if (nodeType === 'ENDPOINT' && effectiveOverlay.size > 0) {
+        return { status: 'COMPLETED' as const, durationMs: 0, hasTraceData: false };
+      }
+      return undefined;
+    },
+    [effectiveOverlay],
+  );
+
   const handleNodeClick = useCallback(
     (nodeId: string) => { onNodeSelect?.(nodeId); },
     [onNodeSelect],
@@ -188,8 +259,8 @@ export function ProcessDiagram({
       )}
 
       <svg
+        ref={zoom.svgRef}
         className={styles.svg}
-        onWheel={zoom.onWheel}
         onPointerDown={zoom.onPointerDown}
         onPointerMove={zoom.onPointerMove}
         onPointerUp={zoom.onPointerUp}
@@ -208,14 +279,31 @@ export function ProcessDiagram({
           >
             <polygon points="0 0, 8 3, 0 6" fill="#9CA3AF" />
           </marker>
+          <marker
+            id="arrowhead-green"
+            markerWidth="8"
+            markerHeight="6"
+            refX="7"
+            refY="3"
+            orient="auto"
+          >
+            <polygon points="0 0, 8 3, 0 6" fill="#3D7C47" />
+          </marker>
         </defs>
 
         <g style={{ transform: zoom.transform, transformOrigin: '0 0' }}>
           {/* Main section top-level edges (not inside compounds) */}
           <g className="edges">
-            {mainSection.edges.filter(e => topLevelEdge(e, mainSection.nodes)).map((edge, i) => (
-              <DiagramEdge key={`${edge.sourceId}-${edge.targetId}-${i}`} edge={edge} />
-            ))}
+            {mainSection.edges.filter(e => topLevelEdge(e, mainSection.nodes)).map((edge, i) => {
+              const sourceHasState = effectiveOverlay?.has(edge.sourceId) || endpointNodeIds.has(edge.sourceId);
+              const targetHasState = effectiveOverlay?.has(edge.targetId) || endpointNodeIds.has(edge.targetId);
+              const isTraversed = effectiveOverlay
+                ? (!!sourceHasState && !!targetHasState)
+                : undefined;
+              return (
+                <DiagramEdge key={`${edge.sourceId}-${edge.targetId}-${i}`} edge={edge} traversed={isTraversed} />
+              );
+            })}
           </g>
 
           {/* Main section nodes */}
@@ -230,6 +318,10 @@ export function ProcessDiagram({
                     selectedNodeId={selectedNodeId}
                     hoveredNodeId={toolbar.hoveredNodeId}
                     nodeConfigs={nodeConfigs}
+                    executionOverlay={effectiveOverlay}
+                    overlayActive={overlayActive}
+                    iterationState={iterationState}
+                    onIterationChange={onIterationChange}
                     onNodeClick={handleNodeClick}
                     onNodeDoubleClick={handleNodeDoubleClick}
                     onNodeEnter={toolbar.onNodeEnter}
@@ -244,6 +336,8 @@ export function ProcessDiagram({
                   isHovered={toolbar.hoveredNodeId === node.id}
                   isSelected={selectedNodeId === node.id}
                   config={node.id ? nodeConfigs?.get(node.id) : undefined}
+                  executionState={getNodeExecutionState(node.id, node.type)}
+                  overlayActive={overlayActive}
                   onClick={() => node.id && handleNodeClick(node.id)}
                   onDoubleClick={() => node.id && handleNodeDoubleClick(node.id)}
                   onMouseEnter={() => node.id && toolbar.onNodeEnter(node.id)}
@@ -264,6 +358,10 @@ export function ProcessDiagram({
               selectedNodeId={selectedNodeId}
               hoveredNodeId={toolbar.hoveredNodeId}
               nodeConfigs={nodeConfigs}
+              executionOverlay={executionOverlay}
+              overlayActive={overlayActive}
+              iterationState={iterationState}
+              onIterationChange={onIterationChange}
               onNodeClick={handleNodeClick}
               onNodeDoubleClick={handleNodeDoubleClick}
               onNodeEnter={toolbar.onNodeEnter}
@@ -345,6 +443,13 @@ function findInChildren(
   return undefined;
 }
 
+function findNodeInSection(
+  nodes: DiagramNodeType[],
+  nodeId: string,
+): boolean {
+  return !!findInChildren(nodes, nodeId) || nodes.some(n => n.id === nodeId);
+}
+
 function topLevelEdge(
   edge: import('../../api/queries/diagrams').DiagramEdge,
   nodes: DiagramNodeType[],
diff --git a/ui/src/components/ProcessDiagram/types.ts b/ui/src/components/ProcessDiagram/types.ts
index 41e153e0..e7a6e516 100644
--- a/ui/src/components/ProcessDiagram/types.ts
+++ b/ui/src/components/ProcessDiagram/types.ts
@@ -1,4 +1,5 @@
-import type { DiagramNode, DiagramEdge } from '../../api/queries/diagrams';
+import type { DiagramNode, DiagramEdge, DiagramLayout } from '../../api/queries/diagrams';
+import type { NodeExecutionState, IterationInfo } from '../ExecutionDiagram/types';
 
 export type NodeAction = 'inspect' | 'toggle-trace' | 'configure-tap' | 'copy-id';
 
@@ -26,4 +27,14 @@ export interface ProcessDiagramProps {
   /** Known route IDs for this application (enables drill-down resolution) */
   knownRouteIds?: Set<string>;
   className?: string;
+  /** Pre-fetched diagram layout (bypasses internal fetch by application/routeId) */
+  diagramLayout?: DiagramLayout;
+  /** Execution overlay: maps diagram node ID → execution state */
+  executionOverlay?: Map<string, NodeExecutionState>;
+  /** Per-compound iteration info: maps compound node ID → iteration info */
+  iterationState?: Map<string, IterationInfo>;
+  /** Called when user changes iteration on a compound stepper */
+  onIterationChange?: (compoundNodeId: string, iterationIndex: number) => void;
+  /** When set, the diagram pans to center this node in the viewport */
+  centerOnNodeId?: string;
 }
diff --git a/ui/src/components/ProcessDiagram/useDiagramData.ts b/ui/src/components/ProcessDiagram/useDiagramData.ts
index c23fa56b..fbf6a3f9 100644
--- a/ui/src/components/ProcessDiagram/useDiagramData.ts
+++ b/ui/src/components/ProcessDiagram/useDiagramData.ts
@@ -1,6 +1,6 @@
 import { useMemo } from 'react';
 import { useDiagramByRoute } from '../../api/queries/diagrams';
-import type { DiagramNode, DiagramEdge } from '../../api/queries/diagrams';
+import type { DiagramNode, DiagramEdge, DiagramLayout } from '../../api/queries/diagrams';
 import type { DiagramSection } from './types';
 import { isErrorCompoundType, isCompletionCompoundType } from './node-colors';
 
@@ -10,8 +10,14 @@ export function useDiagramData(
   application: string,
   routeId: string,
   direction: 'LR' | 'TB' = 'LR',
+  preloadedLayout?: DiagramLayout,
 ) {
-  const { data: layout, isLoading, error } = useDiagramByRoute(application, routeId, direction);
+  // When a preloaded layout is provided, disable the internal fetch
+  const fetchApp = preloadedLayout ? undefined : application;
+  const fetchRoute = preloadedLayout ? undefined : routeId;
+  const { data: fetchedLayout, isLoading, error } = useDiagramByRoute(fetchApp, fetchRoute, direction);
+
+  const layout = preloadedLayout ?? fetchedLayout;
 
   const result = useMemo(() => {
     if (!layout?.nodes) {
@@ -106,7 +112,11 @@ export function useDiagramData(
     return { sections, totalWidth, totalHeight };
   }, [layout]);
 
-  return { ...result, isLoading, error };
+  return {
+    ...result,
+    isLoading: preloadedLayout ? false : isLoading,
+    error: preloadedLayout ? null : error,
+  };
 }
 
 /** Shift all node coordinates by subtracting an offset, recursively. */
diff --git a/ui/src/components/ProcessDiagram/useZoomPan.ts b/ui/src/components/ProcessDiagram/useZoomPan.ts
index 27c68113..dcdb9dc5 100644
--- a/ui/src/components/ProcessDiagram/useZoomPan.ts
+++ b/ui/src/components/ProcessDiagram/useZoomPan.ts
@@ -1,4 +1,4 @@
-import { useCallback, useRef, useState } from 'react';
+import { useCallback, useEffect, useRef, useState } from 'react';
 
 interface ZoomPanState {
   scale: number;
@@ -20,19 +20,24 @@ export function useZoomPan() {
   const isPanning = useRef(false);
   const panStart = useRef({ x: 0, y: 0 });
   const containerRef = useRef<HTMLDivElement>(null);
+  const svgRef = useRef<SVGSVGElement>(null);
 
   const clampScale = (s: number) => Math.min(MAX_SCALE, Math.max(MIN_SCALE, s));
 
   /** Returns the CSS transform string for the content <g> element. */
   const transform = `translate(${state.translateX}px, ${state.translateY}px) scale(${state.scale})`;
 
-  const onWheel = useCallback(
-    (e: React.WheelEvent<SVGSVGElement>) => {
+  // Attach wheel listener with { passive: false } so preventDefault() stops page scroll.
+  // React's onWheel is passive by default and cannot prevent scrolling.
+  useEffect(() => {
+    const svg = svgRef.current;
+    if (!svg) return;
+    const handler = (e: WheelEvent) => {
       e.preventDefault();
       const direction = e.deltaY < 0 ? 1 : -1;
       const factor = 1 + direction * ZOOM_STEP;
 
-      const rect = (e.currentTarget as SVGSVGElement).getBoundingClientRect();
+      const rect = svg.getBoundingClientRect();
       const cursorX = e.clientX - rect.left;
       const cursorY = e.clientY - rect.top;
 
@@ -45,9 +50,10 @@ export function useZoomPan() {
           translateY: cursorY - scaleRatio * (cursorY - prev.translateY),
         };
       });
-    },
-    [],
-  );
+    };
+    svg.addEventListener('wheel', handler, { passive: false });
+    return () => svg.removeEventListener('wheel', handler);
+  }, []);
 
   const onPointerDown = useCallback(
     (e: React.PointerEvent<SVGSVGElement>) => {
@@ -158,10 +164,10 @@ export function useZoomPan() {
   return {
     state,
     containerRef,
+    svgRef,
     transform,
     panTo,
     resetView,
-    onWheel,
     onPointerDown,
     onPointerMove,
     onPointerUp,
diff --git a/ui/src/pages/ExchangeDetail/ExchangeDetail.module.css b/ui/src/pages/ExchangeDetail/ExchangeDetail.module.css
index 5c977839..2d18e19f 100644
--- a/ui/src/pages/ExchangeDetail/ExchangeDetail.module.css
+++ b/ui/src/pages/ExchangeDetail/ExchangeDetail.module.css
@@ -265,6 +265,17 @@
   padding: 12px 16px;
 }
 
+/* ==========================================================================
+   EXECUTION DIAGRAM CONTAINER (Flow view)
+   ========================================================================== */
+.executionDiagramContainer {
+  height: 600px;
+  border: 1px solid var(--border, #E4DFD8);
+  border-radius: var(--radius-md, 8px);
+  overflow: hidden;
+  margin-bottom: 16px;
+}
+
 /* ==========================================================================
    DETAIL SPLIT (IN / OUT panels)
    ========================================================================== */
diff --git a/ui/src/pages/ExchangeDetail/ExchangeDetail.tsx b/ui/src/pages/ExchangeDetail/ExchangeDetail.tsx
index afdb6ce5..70216452 100644
--- a/ui/src/pages/ExchangeDetail/ExchangeDetail.tsx
+++ b/ui/src/pages/ExchangeDetail/ExchangeDetail.tsx
@@ -2,19 +2,21 @@ import { useState, useMemo, useCallback, useEffect } from 'react'
 import { useParams, useNavigate } from 'react-router'
 import {
   Badge, StatusDot, MonoText, CodeBlock, InfoCallout,
-  ProcessorTimeline, Spinner, RouteFlow, useToast,
+  ProcessorTimeline, Spinner, useToast,
   LogViewer, ButtonGroup, SectionHeader, useBreadcrumb,
   Modal, Tabs, Button, Select, Input, Textarea,
+  useGlobalFilters,
 } from '@cameleer/design-system'
-import type { ProcessorStep, RouteNode, NodeBadge, LogEntry, ButtonGroupItem } from '@cameleer/design-system'
+import type { ProcessorStep, NodeBadge, LogEntry, ButtonGroupItem } from '@cameleer/design-system'
 import { useExecutionDetail, useProcessorSnapshot } from '../../api/queries/executions'
 import { useCorrelationChain } from '../../api/queries/correlation'
-import { useDiagramLayout } from '../../api/queries/diagrams'
-import { buildFlowSegments, toFlowSegments } from '../../utils/diagram-mapping'
 import { useTracingStore } from '../../stores/tracing-store'
 import { useApplicationConfig, useUpdateApplicationConfig, useReplayExchange } from '../../api/queries/commands'
 import { useAgents } from '../../api/queries/agents'
 import { useApplicationLogs } from '../../api/queries/logs'
+import { useRouteCatalog } from '../../api/queries/catalog'
+import { ExecutionDiagram } from '../../components/ExecutionDiagram'
+import type { NodeAction, NodeConfig } from '../../components/ProcessDiagram/types'
 import styles from './ExchangeDetail.module.css'
 
 const LOG_LEVEL_ITEMS: ButtonGroupItem[] = [
@@ -88,7 +90,6 @@ export default function ExchangeDetail() {
 
   const { data: detail, isLoading } = useExecutionDetail(id ?? null)
   const { data: correlationData } = useCorrelationChain(detail?.correlationId ?? null)
-  const { data: diagram } = useDiagramLayout(detail?.diagramContentHash ?? null)
 
   const [timelineView, setTimelineView] = useState<'gantt' | 'flow'>('gantt')
   const [logSearch, setLogSearch] = useState('')
@@ -170,33 +171,6 @@ export default function ExchangeDetail() {
   const inputBody = snapshot?.inputBody ?? null
   const outputBody = snapshot?.outputBody ?? null
 
-  // Build RouteFlow nodes from diagram + execution data, split into flow segments
-  const { routeFlows, flowNodeIds } = useMemo(() => {
-    if (diagram?.nodes) {
-      const { flows, nodeIds } = buildFlowSegments(diagram.nodes, procList)
-      // Apply badges to each node across all flows
-      let idx = 0
-      const badgedFlows = flows.map(flow => ({
-        ...flow,
-        nodes: flow.nodes.map(node => ({
-          ...node,
-          badges: badgesFor(nodeIds[idx++]),
-        })),
-      }))
-      return { routeFlows: badgedFlows, flowNodeIds: nodeIds }
-    }
-    // Fallback: build from processor list (no diagram available)
-    const nodes = processors.map((p) => ({
-      name: p.name,
-      type: 'process' as RouteNode['type'],
-      durationMs: p.durationMs,
-      status: p.status,
-      badges: badgesFor(p.name),
-    }))
-    const { flows } = toFlowSegments(nodes)
-    return { routeFlows: flows, flowNodeIds: [] as string[] }
-  }, [diagram, processors, procList, tracedMap])
-
   // ProcessorId lookup: timeline index → processorId
   const processorIds: string[] = useMemo(() => {
     const ids: string[] = []
@@ -208,12 +182,6 @@ export default function ExchangeDetail() {
     return ids
   }, [procList])
 
-  // Map flow display index → processor tree index (for snapshot API)
-  // flowNodeIds already contains processor IDs in flow-order
-  const flowToTreeIndex = useMemo(() =>
-    flowNodeIds.map(pid => pid ? processorIds.indexOf(pid) : -1),
-    [flowNodeIds, processorIds],
-  )
 
   // ── Tracing toggle ──────────────────────────────────────────────────────
   const { toast } = useToast()
@@ -248,6 +216,36 @@ export default function ExchangeDetail() {
     })
   }, [detail, app, appConfig, tracingStore, updateConfig, toast])
 
+  // ── ExecutionDiagram support ──────────────────────────────────────────
+  const { timeRange } = useGlobalFilters()
+  const { data: catalog } = useRouteCatalog(
+    timeRange.start.toISOString(),
+    timeRange.end.toISOString(),
+  )
+
+  const knownRouteIds = useMemo(() => {
+    if (!catalog || !app) return new Set<string>()
+    const appEntry = (catalog as Array<{ appId: string; routes?: Array<{ routeId: string }> }>)
+      .find(a => a.appId === app)
+    return new Set((appEntry?.routes ?? []).map(r => r.routeId))
+  }, [catalog, app])
+
+  const nodeConfigs = useMemo(() => {
+    const map = new Map<string, NodeConfig>()
+    if (tracedMap) {
+      for (const pid of Object.keys(tracedMap)) {
+        map.set(pid, { traceEnabled: true })
+      }
+    }
+    return map
+  }, [tracedMap])
+
+  const handleNodeAction = useCallback((nodeId: string, action: NodeAction) => {
+    if (action === 'toggle-trace') {
+      handleToggleTracing(nodeId)
+    }
+  }, [handleToggleTracing])
+
   // ── Replay ─────────────────────────────────────────────────────────────
   const { data: liveAgents } = useAgents('LIVE', detail?.applicationName)
   const replay = useReplayExchange()
@@ -461,9 +459,9 @@ export default function ExchangeDetail() {
             </button>
           </div>
         </div>
-        <div className={styles.timelineBody}>
-          {timelineView === 'gantt' ? (
-            processors.length > 0 ? (
+        {timelineView === 'gantt' && (
+          <div className={styles.timelineBody}>
+            {processors.length > 0 ? (
               <ProcessorTimeline
                 processors={processors}
                 totalMs={detail.durationMs}
@@ -481,33 +479,23 @@ export default function ExchangeDetail() {
               />
             ) : (
               <InfoCallout>No processor data available</InfoCallout>
-            )
-          ) : (
-            routeFlows.length > 0 ? (
-              <RouteFlow
-                flows={routeFlows}
-                onNodeClick={(_node, index) => {
-                  const treeIdx = flowToTreeIndex[index]
-                  if (treeIdx >= 0) setSelectedProcessorIndex(treeIdx)
-                }}
-                selectedIndex={flowToTreeIndex.indexOf(activeIndex)}
-                getActions={(_node, index) => {
-                  const pid = flowNodeIds[index] ?? ''
-                  if (!pid || !detail?.applicationName) return []
-                  return [{
-                    label: tracingStore.isTraced(app, pid) ? 'Disable Tracing' : 'Enable Tracing',
-                    onClick: () => handleToggleTracing(pid),
-                    disabled: updateConfig.isPending,
-                  }]
-                }}
-              />
-            ) : (
-              <Spinner />
-            )
-          )}
-        </div>
+            )}
+          </div>
+        )}
       </div>
 
+      {timelineView === 'flow' && detail && (
+        <div className={styles.executionDiagramContainer}>
+          <ExecutionDiagram
+            executionId={id!}
+            executionDetail={detail}
+            knownRouteIds={knownRouteIds}
+            onNodeAction={handleNodeAction}
+            nodeConfigs={nodeConfigs}
+          />
+        </div>
+      )}
+
       {/* Exchange-level body (start/end of route) */}
       {detail && (detail.inputBody || detail.outputBody) && (
         <div className={styles.detailSplit}>