refactor(client): localize nested Tool call trees

packages/client/runtime/src/client/index.ts

@@ -8,7 +8,7 @@ import { SessionsService } from './sessions/service.ts'
 import type { SessionListState } from './sessions/service.ts'
 import { SessionHistoryService } from './session-history/service.ts'
 import { WorkspacesService } from './workspaces/service.ts'
-import type { ConversationSnapshot, RunningToolCall, ToolResultNode } from './sessions/conversation.ts'
+import type { ConversationSnapshot } from './sessions/conversation.ts'
 import type { UseProjection } from './sessions/projection-store.ts'
 
 export { SlotsService } from './slots.ts'
@@ -49,10 +49,10 @@ export type {
 } from './contract/store.ts'
 export type {
   AssistantBlock, AssistantMessageNode, AssistantProvenanceView, AssistantRequestConfig,
-  AssistantTiming, CodeSubCall, CommandNode, CompactionSummaryNode, ComposerPhase,
+  AssistantTiming, CommandNode, CompactionSummaryNode, ComposerPhase,
   ContextMessageNode, ConversationNode, ConversationSnapshot, ModelRetryNode, QueuedMessage,
   RunningToolCall,
-  SteeringMessageNode, TodoItem, ToolResultNode, TurnErrorNode, UnknownSurfaceNode, UserMessageNode,
+  SteeringMessageNode, TodoItem, ToolCallBlock, ToolResultNode, TurnErrorNode, UnknownSurfaceNode, UserMessageNode,
 } from './sessions/conversation.ts'
 export type {
   ConversationContext, ConversationContextOriginKind,
@@ -89,13 +89,6 @@ declare module '@deepseek-ai/dsh-type-meta' {
 /** The conversation-snapshot selector hook supplied to session-scoped UI entries. */
 export type UseConversationSession = SnapshotSelectorHook<ConversationSnapshot>
 
-/**
- * One tool call as the chat flow renders it: still-running (spinner card) or
- * settled (result node). The fold produces both shapes; toolview components
- * narrow on the discriminant fields.
- */
-export type ToolCallBlock = RunningToolCall | ToolResultNode
-
 declare module '@deepseek-ai/dsh-client-ui-slots' {
   /**
    * Session standard kit, real members (ui-slots declares the empty seat;

packages/client/runtime/src/client/session-history/history-fold.ts

@@ -1,4 +1,3 @@
-import type { ContentBlock } from '@deepseek-ai/dsh-llm/types'
 import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
 import {
   SurfaceManager, isSurfaceEligibleType, isSurfaceEvent,
@@ -7,7 +6,7 @@ import type {
   HistoryEntry, ToolCallView, ToolResultView,
 } from '@deepseek-ai/dsh-client-connection/client'
 import type {
-  AssistantRequestConfig, AssistantTiming, CodeSubCall, ConversationNode,
+  AssistantRequestConfig, AssistantTiming, ConversationNode,
   PartialAssistant, RunningToolCall,
 } from '../sessions/conversation.ts'
 import { toAssistantBlocks } from '../sessions/conversation.ts'
@@ -20,6 +19,7 @@ import type { ConversationPromptSnapshot } from '../sessions/request-inspection.
 import { PartialAccumulator } from '../sessions/partial.ts'
 import type { AssistantStepMetadata } from '../sessions/assistant-timing.ts'
 import { indexAssistantStepTiming, settledAssistantTiming } from '../sessions/assistant-timing.ts'
+import { ToolCallTree } from '../sessions/tool-call-tree.ts'
 
 interface CallIndexEntry {
   name: string
@@ -41,7 +41,6 @@ export interface ConversationHistoryProjection {
   interruptedNodes: readonly ConversationNode[]
   partial: PartialAssistant | null
   runningCalls: readonly RunningToolCall[]
-  codeDispatches: ReadonlyMap<string, readonly CodeSubCall[]>
 }
 
 function replacementCrossesWindowHead(event: SessionEvent, baseSeq: number): boolean {
@@ -177,6 +176,7 @@ function materializeNode(
         meta: event.data.meta,
         callView: call?.callView ?? null,
         resultView,
+        subCalls: [],
       }
     }
     default:
@@ -188,74 +188,22 @@ function materializeNode(
 }
 /* jscpd:ignore-end */
 
-function projectTransient(entries: readonly HistoryEntry[]): Pick<
+interface TransientProjection extends Pick<
   ConversationHistoryProjection,
-  'interruptedNodes' | 'partial' | 'runningCalls' | 'codeDispatches'
+  'interruptedNodes' | 'partial' | 'runningCalls'
 > {
+  toolCallTree: ToolCallTree
+}
+
+function projectTransient(entries: readonly HistoryEntry[]): TransientProjection {
   let partial: PartialAccumulator | null = null
   const openCalls = new Map<string, RunningToolCall>()
   const interruptedNodes: ConversationNode[] = []
-  const codeDispatches = new Map<string, readonly CodeSubCall[]>()
+  const toolCallTree = new ToolCallTree()
 
   for (const entry of entries) {
     const { event } = entry
-    if ((event.type as string) === 'tool/code-dispatch-start') {
-      const data = event.data as unknown as {
-        parentCallId: string
-        subCallId: string
-        name: string
-        arguments: unknown
-      }
-      const siblings = codeDispatches.get(data.parentCallId) ?? []
-      // The independent replay emits the same public running-call shape as
-      // Chat without reading or mutating Session's live index.
-      /* jscpd:ignore-start */
-      codeDispatches.set(data.parentCallId, [...siblings, {
-        callId: data.subCallId,
-        name: data.name,
-        argsRaw: JSON.stringify(data.arguments),
-        turn: 0,
-        step: 0,
-        time: event.time,
-        callView: null,
-      }])
-      /* jscpd:ignore-end */
-      continue
-    }
-    if ((event.type as string) === 'tool/code-dispatch') {
-      const data = event.data as unknown as {
-        parentCallId: string
-        subCallId: string
-        name: string
-        arguments: unknown
-        isError: boolean
-        content: ContentBlock[]
-      }
-      const siblings = codeDispatches.get(data.parentCallId) ?? []
-      const at = siblings.findIndex(sub => sub.callId === data.subCallId)
-      const started = at === -1 ? undefined : siblings[at]
-      // History independently reproduces the public settled-call shape instead
-      // of consuming Session's live code-dispatch projection.
-      /* jscpd:ignore-start */
-      const settled: CodeSubCall = {
-        kind: 'tool-result', seq: event.seq, time: event.time,
-        callId: data.subCallId,
-        call: { name: data.name, argsRaw: JSON.stringify(data.arguments) },
-        callTime: started?.time ?? null,
-        content: data.content,
-        isError: data.isError,
-        callView: null,
-        resultView: null,
-      }
-      codeDispatches.set(
-        data.parentCallId,
-        at === -1
-          ? [...siblings, settled]
-          : siblings.map((sub, index) => index === at ? settled : sub),
-      )
-      /* jscpd:ignore-end */
-      continue
-    }
+    if (toolCallTree.apply(event)) continue
     switch (event.type) {
       case 'assistant/chunk': {
         const { turn, step, chunk } = event.data
@@ -280,6 +228,7 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
           step: event.data.step,
           time: event.time,
           callView: entry.view?.for === 'call' ? entry.view.view : null,
+          subCalls: [],
         })
         /* jscpd:ignore-end */
         break
@@ -317,6 +266,7 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
             error: { name: 'Interrupted', code: 'interrupted' },
             callView: call.callView,
             resultView: null,
+            subCalls: [],
           })
           /* jscpd:ignore-end */
         }
@@ -331,7 +281,7 @@ function projectTransient(entries: readonly HistoryEntry[]): Pick<
     interruptedNodes,
     partial: partial?.toPartial() ?? null,
     runningCalls: [...openCalls.values()],
-    codeDispatches,
+    toolCallTree,
   }
 }
 
@@ -462,9 +412,17 @@ export function projectConversationHistory(
     }
   }
 
+  const transient = projectTransient(entries)
+  const projectedEventNodes = transient.toolCallTree.projectNodes(eventNodes)
+  const projectedContexts = contexts.map((context): ConversationContext => {
+    const nodes = transient.toolCallTree.projectNodes(context.nodes)
+    return nodes === context.nodes ? context : { ...context, nodes }
+  })
   return {
-    eventNodes,
-    contexts,
-    ...projectTransient(entries),
+    eventNodes: projectedEventNodes,
+    contexts: projectedContexts,
+    interruptedNodes: transient.toolCallTree.projectNodes(transient.interruptedNodes),
+    partial: transient.partial,
+    runningCalls: transient.toolCallTree.projectRunningCalls(transient.runningCalls),
   }
 }

packages/client/runtime/src/client/sessions/conversation.ts

@@ -174,6 +174,8 @@ export interface ToolResultNode {
   callView: ToolCallView | null
   /** Host-computed render intent from this tool/result's wire view; null = same default. */
   resultView: ToolResultView | null
+  /** Child calls owned by this call, in dispatch order. */
+  subCalls: readonly ToolCallBlock[]
 }
 
 /**
@@ -263,21 +265,6 @@ export type ConversationNode =
   | CompactionSummaryNode
   | UnknownSurfaceNode
 
-/**
- * One `run_code` sub-dispatch materialized in the native call-block shapes so
- * every consumer (tool rows, details panel) renders it through the exact
- * components that render a native call: a started-but-unsettled sub-call is a
- * {@link RunningToolCall} (rows derive the running state from the shape,
- * exactly as for native calls) and its `tool/code-dispatch` settlement
- * replaces it in place with the {@link ToolResultNode} form. Never part of
- * the transcript `nodes` flow — sub-calls live under their parent via
- * {@link ConversationSnapshot.codeDispatches}. `callId` is the deterministic
- * sub-call id (`<parent>:code:<n>`); the call side carries the sub-tool name
- * and its JSON-stringified logged arguments; `content`/`isError` are the
- * settled sub-call's complete logged outcome.
- */
-export type CodeSubCall = RunningToolCall | ToolResultNode
-
 /** In-flight tool card material: tool/call seen, tool/result not yet. */
 export interface RunningToolCall {
   callId: string
@@ -289,8 +276,12 @@ export interface RunningToolCall {
   time: number
   /** Host-computed render intent riding the tool/call frame; null = generic JSON card. */
   callView: ToolCallView | null
+  /** Child calls owned by this call, in dispatch order. */
+  subCalls: readonly ToolCallBlock[]
 }
 
+/** One running or settled call, recursively owning its child calls. */
+export type ToolCallBlock = RunningToolCall | ToolResultNode
 
 /** One transient inbox occurrence from the authoritative `session/queue` snapshot. */
 export interface QueuedMessage {
@@ -355,13 +346,6 @@ export interface ConversationSnapshot {
   turnEnds: ReadonlyMap<number, number>
   partial: PartialAssistant | null
   runningCalls: readonly RunningToolCall[]
-  /**
-   * `run_code` sub-dispatches grouped under their parent callId, in dispatch
-   * order. Populated from in-window `tool/code-dispatch` events (live and
-   * replay identically); the per-parent array reference is stable across
-   * unrelated snapshot swaps (memo premise, same regime as `nodes`).
-   */
-  codeDispatches: ReadonlyMap<string, readonly CodeSubCall[]>
   pending: readonly PendingInteraction[]
   /** Authoritative transient inbox snapshot, including queued and steering placements. */
   queue: readonly QueuedMessage[]

packages/client/runtime/src/client/sessions/history.ts

@@ -1,7 +1,7 @@
 import type { ToolSchema } from '@deepseek-ai/dsh-llm/types'
 import type { HistoryEntry } from '@deepseek-ai/dsh-client-connection/client'
 import type {
-  CodeSubCall, ConversationNode, PartialAssistant, RunningToolCall,
+  ConversationNode, PartialAssistant, RunningToolCall,
 } from './conversation.ts'
 import type { ConversationContext } from './conversation-context.ts'
 import { projectConversationHistory } from '../session-history/history-fold.ts'
@@ -34,7 +34,6 @@ export interface SessionHistoryInspection {
   interruptedNodes: readonly ConversationNode[]
   partial: PartialAssistant | null
   runningCalls: readonly RunningToolCall[]
-  codeDispatches: ReadonlyMap<string, readonly CodeSubCall[]>
 }
 
 /**
@@ -112,9 +111,6 @@ export function createHistoryInspection(
     get runningCalls() {
       return conversationProjection().runningCalls
     },
-    get codeDispatches() {
-      return conversationProjection().codeDispatches
-    },
     get requests() {
       return requestProjection().requests
     },

packages/client/runtime/src/client/sessions/session.ts

@@ -13,7 +13,7 @@ import type {
 import { transportError } from '@deepseek-ai/dsh-host-apiproxy/api'
 import type { SessionFace } from '../contract/session.ts'
 import type {
-  CodeSubCall, ComposerPhase, ConversationNode, ConversationSnapshot, ModelRetryNode,
+  ComposerPhase, ConversationNode, ConversationSnapshot, ModelRetryNode,
   OpenState, PromptError, QueuedMessage, RunningToolCall,
 } from './conversation.ts'
 import type { PendingInteraction } from './pending.ts'
@@ -24,6 +24,7 @@ import { Notifier } from './notifier.ts'
 import { isVisibleAssistantChunk, PartialAccumulator } from './partial.ts'
 import { ProjectionValueStore } from './projection-store.ts'
 import type { ProjectionsBaseline } from './projection-store.ts'
+import { ToolCallTree } from './tool-call-tree.ts'
 
 /** Messages requested per history page. */
 export const PAGE_MESSAGES = 50
@@ -129,11 +130,8 @@ export class Session implements SessionFace {
   private queued: QueuedMessage[] = []
   private queueRev = 0
   private queueCache: { rev: number; value: QueuedMessage[] } | null = null
-  /** `run_code` sub-dispatches by parent callId (window-derived, like openCalls). Appends
-   *  copy-on-write the per-parent array so published snapshot references never mutate. */
-  private codeDispatches = new Map<string, readonly CodeSubCall[]>()
-  private dispatchesRev = 0
-  private dispatchesCache: { rev: number; value: ReadonlyMap<string, readonly CodeSubCall[]> } | null = null
+  /** Window-derived child-call lifecycle and immutable tree projection. */
+  private readonly toolCallTree = new ToolCallTree()
   private running = false
   private address: SubagentAddress | undefined
   private parentAvailable = false
@@ -746,65 +744,10 @@ export class Session implements SessionFace {
       this.derivedRev++
       return
     }
-    // The `tool/code-dispatch-start`/`tool/code-dispatch` pair is declared by
-    // the host-side dsh-tools plugin whose types cannot enter the client
-    // program (its host Context merges collide with the client's), so this
-    // wire consumer narrows them structurally — the same posture as every
-    // other cross-wire event payload.
-    if ((event.type as string) === 'tool/code-dispatch-start') {
-      // A started sub-dispatch enters the index as a RunningToolCall — the
-      // exact shape a native in-flight call renders from — under its parent
-      // run_code callId; it never joins the surface flow.
-      const data = event.data as unknown as {
-        parentCallId: string
-        subCallId: string
-        name: string
-        arguments: unknown
-      }
-      const running: CodeSubCall = {
-        callId: data.subCallId, name: data.name,
-        argsRaw: JSON.stringify(data.arguments),
-        turn: 0, step: 0, time: event.time, callView: null,
-      }
-      const siblings = this.codeDispatches.get(data.parentCallId) ?? []
-      this.codeDispatches.set(data.parentCallId, [...siblings, running])
-      this.dispatchesRev++
-      return
-    }
-    if ((event.type as string) === 'tool/code-dispatch') {
-      // Settlement replaces the running entry in place (same array position,
-      // so parallel sub-calls keep their start order) with the
-      // ToolResultNode form; a settle with no observed start (history window
-      // cut mid-pair, or a pre-start-event log) appends directly.
-      const data = event.data as unknown as {
-        parentCallId: string
-        subCallId: string
-        name: string
-        arguments: unknown
-        isError: boolean
-        content: ContentBlock[]
-      }
-      const siblings = this.codeDispatches.get(data.parentCallId) ?? []
-      const at = siblings.findIndex(sub => sub.callId === data.subCallId)
-      const started = at === -1 ? undefined : siblings[at]
-      const settled: CodeSubCall = {
-        kind: 'tool-result', seq: event.seq, time: event.time,
-        callId: data.subCallId,
-        call: { name: data.name, argsRaw: JSON.stringify(data.arguments) },
-        // Duration source: the paired start's time when observed; null =
-        // unknown (settle-only window), matching the native tool-result
-        // contract so views never present a fabricated zero duration.
-        callTime: started === undefined ? null : started.time,
-        content: data.content, isError: data.isError,
-        callView: null, resultView: null,
-      }
-      this.codeDispatches.set(
-        data.parentCallId,
-        at === -1 ? [...siblings, settled] : siblings.map((sub, index) => (index === at ? settled : sub)),
-      )
-      this.dispatchesRev++
-      return
-    }
+    // These lifecycle events are declared by a host-only plugin whose Context
+    // types cannot enter the client program. ToolCallTree owns their structural
+    // wire narrowing, pairing, and nested snapshot projection.
+    if (this.toolCallTree.apply(event)) return
     switch (event.type) {
       case 'turn/start':
         this.lastStepByTurn.set(event.data.turn, 0)
@@ -834,6 +777,7 @@ export class Session implements SessionFace {
           callId: String(event.data.callId), name: event.data.name, argsRaw: event.data.arguments,
           turn: event.data.turn, step: event.data.step, time: event.time,
           callView: view?.for === 'call' ? view.view : null,
+          subCalls: [],
         })
         this.callsRev++
         return
@@ -901,7 +845,7 @@ export class Session implements SessionFace {
             call: { name: call.name, argsRaw: call.argsRaw },
             callTime: call.time,
             content: [], isError: true, error: { name: 'Interrupted', code: 'interrupted' },
-            callView: call.callView, resultView: null,
+            callView: call.callView, resultView: null, subCalls: [],
           })
           this.derivedRev++
         }
@@ -948,8 +892,7 @@ export class Session implements SessionFace {
     this.turnTimingsRev++
     this.turnEnds = new Map()
     this.turnEndsRev++
-    this.codeDispatches = new Map()
-    this.dispatchesRev++
+    this.toolCallTree.reset()
     for (let i = 0; i < this.events.length; i++) {
       const event = this.events[i]
       /* v8 ignore next -- dense-array guard: i stays within events.length, so the undefined arm needs a sparse array no caller builds. */
@@ -988,22 +931,18 @@ export class Session implements SessionFace {
     if (this.pendingCache === null || this.pendingCache.rev !== this.pendingRev) {
       this.pendingCache = { rev: this.pendingRev, value: [...this.pending.values()] }
     }
-    if (this.dispatchesCache === null || this.dispatchesCache.rev !== this.dispatchesRev) {
-      this.dispatchesCache = { rev: this.dispatchesRev, value: new Map(this.codeDispatches) }
-    }
     if (this.queueCache === null || this.queueCache.rev !== this.queueRev) {
       this.queueCache = { rev: this.queueRev, value: this.queued }
     }
     const partial = this.partial?.toPartial() ?? null
     return {
       sessionId: this.sessionId,
-      nodes,
+      nodes: this.toolCallTree.projectNodes(nodes),
       turnTimings: this.turnTimingsCache.value,
       turnEnds: this.turnEndsCache.value,
       partial,
-      runningCalls: this.callsCache.value,
+      runningCalls: this.toolCallTree.projectRunningCalls(this.callsCache.value),
       pending: this.pendingCache.value,
-      codeDispatches: this.dispatchesCache.value,
       queue: this.queueCache.value,
       running: this.running,
       subagent: this.address === undefined

packages/client/runtime/src/client/sessions/tool-call-tree.ts

@@ -0,0 +1,171 @@
+import type { ContentBlock } from '@deepseek-ai/dsh-llm/types'
+import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
+import type {
+  ConversationNode, RunningToolCall, ToolCallBlock, ToolResultNode,
+} from './conversation.ts'
+
+interface ProjectedBlock {
+  source: ToolCallBlock
+  children: readonly ToolCallBlock[]
+  value: ToolCallBlock
+}
+
+function sameBlocks(
+  left: readonly ToolCallBlock[],
+  right: readonly ToolCallBlock[],
+): boolean {
+  return left.length === right.length
+    && left.every((block, index) => block === right[index])
+}
+
+/**
+ * Owns Code Dispatch pairing and projects its private parent index into the
+ * recursive Tool call contract exposed by conversation snapshots.
+ */
+export class ToolCallTree {
+  private readonly childrenByParent = new Map<string, readonly ToolCallBlock[]>()
+  private readonly projectedByCall = new Map<string, ProjectedBlock>()
+  private revision = 0
+  private nodesCache: {
+    source: readonly ConversationNode[]
+    revision: number
+    value: readonly ConversationNode[]
+  } | null = null
+  private runningCache: {
+    source: readonly RunningToolCall[]
+    revision: number
+    value: readonly RunningToolCall[]
+  } | null = null
+
+  /** Forget all event-derived child calls before replaying a new window. */
+  reset(): void {
+    this.childrenByParent.clear()
+    this.projectedByCall.clear()
+    this.revision++
+  }
+
+  /**
+   * Fold one event when it belongs to the Code Dispatch lifecycle.
+   * @param event - Session event from the current live or history window.
+   * @returns Whether the event was consumed as a child-call lifecycle event.
+   */
+  apply(event: SessionEvent): boolean {
+    if ((event.type as string) === 'tool/code-dispatch-start') {
+      const data = event.data as unknown as {
+        parentCallId: string
+        subCallId: string
+        name: string
+        arguments: unknown
+      }
+      const running: RunningToolCall = {
+        callId: data.subCallId,
+        name: data.name,
+        argsRaw: JSON.stringify(data.arguments),
+        turn: 0,
+        step: 0,
+        time: event.time,
+        callView: null,
+        subCalls: [],
+      }
+      const siblings = this.childrenByParent.get(data.parentCallId) ?? []
+      this.childrenByParent.set(data.parentCallId, [...siblings, running])
+      this.revision++
+      return true
+    }
+    if ((event.type as string) !== 'tool/code-dispatch') return false
+    const data = event.data as unknown as {
+      parentCallId: string
+      subCallId: string
+      name: string
+      arguments: unknown
+      isError: boolean
+      content: ContentBlock[]
+    }
+    const siblings = this.childrenByParent.get(data.parentCallId) ?? []
+    const at = siblings.findIndex(sub => sub.callId === data.subCallId)
+    const started = at === -1 ? undefined : siblings[at]
+    const settled: ToolResultNode = {
+      kind: 'tool-result',
+      seq: event.seq,
+      time: event.time,
+      callId: data.subCallId,
+      call: { name: data.name, argsRaw: JSON.stringify(data.arguments) },
+      callTime: started?.time ?? null,
+      content: data.content,
+      isError: data.isError,
+      callView: null,
+      resultView: null,
+      subCalls: [],
+    }
+    this.childrenByParent.set(
+      data.parentCallId,
+      at === -1
+        ? [...siblings, settled]
+        : siblings.map((sub, index) => index === at ? settled : sub),
+    )
+    this.revision++
+    return true
+  }
+
+  /**
+   * Attach recursively projected children to all settled roots in a node list.
+   * @param nodes - Cache-stable base conversation nodes.
+   * @returns The original list when no root changed, otherwise a structurally shared list.
+   */
+  projectNodes(nodes: readonly ConversationNode[]): readonly ConversationNode[] {
+    if (this.nodesCache?.source === nodes && this.nodesCache.revision === this.revision) {
+      return this.nodesCache.value
+    }
+    let changed = false
+    const projected = nodes.map((node): ConversationNode => {
+      if (node.kind !== 'tool-result') return node
+      const value = this.projectBlock(node) as ToolResultNode
+      changed ||= value !== node
+      return value
+    })
+    const value = changed ? projected : nodes
+    this.nodesCache = { source: nodes, revision: this.revision, value }
+    return value
+  }
+
+  /**
+   * Attach recursively projected children to all running root calls.
+   * @param calls - Cache-stable base running calls.
+   * @returns The original list when no root changed, otherwise a structurally shared list.
+   */
+  projectRunningCalls(calls: readonly RunningToolCall[]): readonly RunningToolCall[] {
+    if (this.runningCache?.source === calls && this.runningCache.revision === this.revision) {
+      return this.runningCache.value
+    }
+    let changed = false
+    const projected = calls.map((call): RunningToolCall => {
+      const value = this.projectBlock(call) as RunningToolCall
+      changed ||= value !== call
+      return value
+    })
+    const value = changed ? projected : calls
+    this.runningCache = { source: calls, revision: this.revision, value }
+    return value
+  }
+
+  private projectBlock(block: ToolCallBlock): ToolCallBlock {
+    const children = this.childrenByParent.get(block.callId) ?? block.subCalls
+    const projectedChildren = children.map(child => this.projectBlock(child))
+    const childValue = sameBlocks(children, projectedChildren)
+      ? children
+      : projectedChildren
+    const cached = this.projectedByCall.get(block.callId)
+    if (cached?.source === block && sameBlocks(cached.children, childValue)) {
+      return cached.value
+    }
+    const value: ToolCallBlock = block.subCalls === childValue
+      ? block
+      : { ...block, subCalls: childValue }
+    this.projectedByCall.set(block.callId, {
+      source: block,
+      children: childValue,
+      value,
+    })
+    return value
+  }
+}

packages/client/runtime/src/client/sessions/transcript-adapter.ts

@@ -103,6 +103,7 @@ function materializeNode(
         meta: event.data.meta,
         callView: call?.callView ?? null,
         resultView,
+        subCalls: [],
       }
     }
     /* v8 ignore next 2 -- defensive arm: only the four surface-eligible types