diff --git a/packages/client/ui-trajectory/src/client/TrajectoryView.tsx b/packages/client/ui-trajectory/src/client/TrajectoryView.tsx
index 95476ac851..70e92f72fd 100644
--- a/packages/client/ui-trajectory/src/client/TrajectoryView.tsx
+++ b/packages/client/ui-trajectory/src/client/TrajectoryView.tsx
@@ -9,6 +9,7 @@ import type {
 } from '@deepseek-ai/dsh-client-runtime/client'
 import {
   deriveTrajectoryContextBranches, trajectoryBranchContainsRequest,
+  trajectoryNodeIdentity,
 } from './context-branches.ts'
 import {
   TrajectoryTable,
@@ -229,9 +230,9 @@ export function TrajectoryView({
   const currentBranch = branches.at(-1)
   if (currentBranch === undefined) throw new Error('trajectory branch projection must not be empty')
   const selectedNodes = useMemo(() => {
-    const selected = new Map(currentBranch.nodes.map(node => [node.seq, node]))
+    const selected = new Map(currentBranch.nodes.map(node => [trajectoryNodeIdentity(node), node]))
     for (const node of interruptedNodes) {
-      selected.set(node.seq, node)
+      selected.set(trajectoryNodeIdentity(node), node)
     }
     return [...selected.values()].sort((left, right) => left.seq - right.seq)
   }, [currentBranch.nodes, interruptedNodes])
diff --git a/packages/client/ui-trajectory/src/client/context-branches.ts b/packages/client/ui-trajectory/src/client/context-branches.ts
index 2501511c50..2f665bb413 100644
--- a/packages/client/ui-trajectory/src/client/context-branches.ts
+++ b/packages/client/ui-trajectory/src/client/context-branches.ts
@@ -23,11 +23,24 @@ interface MutableBranch {
   key: string
   contexts: ConversationContext[]
   latest: ConversationContext
-  nodes: Map<number, ConversationNode>
+  nodes: Map<string, ConversationNode>
   startSeq: number
   retainedSurfaceSeqs: Set<number>
 }
 
+/**
+ * Resolve the identity used while coalescing one trajectory branch.
+ * Synthetic tool interruptions share their closing boundary seq, so their
+ * call ids distinguish parallel roots without inventing false event order.
+ * @param node - projected conversation node.
+ * @returns branch-local semantic identity.
+ */
+export function trajectoryNodeIdentity(node: ConversationNode): string {
+  return node.kind === 'tool-result'
+    ? `tool-result\u0000${String(node.seq)}\u0000${node.callId}`
+    : `seq\u0000${String(node.seq)}`
+}
+
 function isCompactionCheckpoint(node: ConversationNode): boolean {
   if (node.kind !== 'context') return false
   const source = node.source
@@ -73,7 +86,7 @@ export function deriveTrajectoryContextBranches(
         latest: context,
         nodes: new Map(
           [...inheritedNodes, ...context.nodes.filter(node => !isCompactionCheckpoint(node))]
-            .map(node => [node.seq, node]),
+            .map(node => [trajectoryNodeIdentity(node), node]),
         ),
         startSeq: context.originSeq ?? Number.NEGATIVE_INFINITY,
         retainedSurfaceSeqs,
@@ -85,7 +98,7 @@ export function deriveTrajectoryContextBranches(
     branch.contexts.push(context)
     branch.latest = context
     for (const node of context.nodes) {
-      if (!isCompactionCheckpoint(node)) branch.nodes.set(node.seq, node)
+      if (!isCompactionCheckpoint(node)) branch.nodes.set(trajectoryNodeIdentity(node), node)
     }
   }
   return mutable.map(branch => ({
diff --git a/packages/client/ui-trajectory/tests/context-branches.spec.ts b/packages/client/ui-trajectory/tests/context-branches.spec.ts
index e608b9fd68..9885e9a4f9 100644
--- a/packages/client/ui-trajectory/tests/context-branches.spec.ts
+++ b/packages/client/ui-trajectory/tests/context-branches.spec.ts
@@ -34,6 +34,23 @@ const current = {
   source: { kind: 'plugin', plugin: 'rewind' },
 } as ConversationNode
 
+function interruptedTool(callId: string): ConversationNode {
+  return {
+    kind: 'tool-result',
+    seq: 19.2,
+    time: 20,
+    callId,
+    call: { name: 'parallel', argsRaw: '{}' },
+    callTime: 10,
+    content: [],
+    isError: true,
+    error: { name: 'Interrupted', code: 'interrupted' },
+    callView: null,
+    resultView: null,
+    subCalls: [],
+  }
+}
+
 function request(
   purpose: RequestView['purpose'],
   startSeq: number,
@@ -99,4 +116,14 @@ describe('trajectory context branches', () => {
 
     expect(branch(1)?.key).toBe(branch(9)?.key)
   })
+
+  it('retains parallel tool interruptions that share one closing boundary', () => {
+    const branch = deriveTrajectoryContextBranches([{
+      id: 0,
+      nodes: [interruptedTool('call-a'), interruptedTool('call-b')],
+    }])[0]
+
+    expect(branch?.nodes.map(node => node.kind === 'tool-result' ? node.callId : undefined))
+      .toEqual(['call-a', 'call-b'])
+  })
 })