fix(client): address conversation assembly review feedback

packages/client/ui-conversation/src/client/contract/slots.ts

@@ -56,11 +56,10 @@ declare module '@deepseek-ai/dsh-client-ui-slots' {
      */
     'conversation.chat.commandview': { kind: 'keyed'; scope: 'session'; owner: CommandRowOwnerProps }
     /**
-     * The chat view's turn-tail chain: rendered between a closing assistant
-     * message's body and its IconActions footer, once per turn (the render
-     * site elects the closing seq). Entries derive a match from the owner
-     * currency before mounting, so presentation components never mount only
-     * to return null; an all-declined chain renders nothing.
+     * The completed Turn Node's extension chain, rendered before that Node's
+     * IconActions. Entries derive a match from the engine-owned Turn and
+     * closing seq before mounting, so presentation components never mount
+     * only to return null; an all-declined chain renders nothing.
      */
     'conversation.chat.turnTail': { kind: 'chain'; scope: 'session'; owner: TurnTailOwnerProps }
     /** Selected Tool call output inside the details panel. */

packages/client/ui-conversation/src/client/conversation-nodes/assistant.ts

@@ -7,7 +7,7 @@ import {
   emptyAssistantBlock, isAppendSurfaceEvent, isTokenDelta, toAssistantBlock, toAssistantBlocks,
 } from '@deepseek-ai/dsh-client-runtime/client'
 import type { AssistantChatData } from '../contract/chat-nodes.ts'
-import { chatNode } from './common.ts'
+import { CHAT_SYNTHETIC_SEQ_OFFSETS, chatNode } from './common.ts'
 
 declare module '@deepseek-ai/dsh-client-ui-conversation/client' {
   interface ChatNodeDataMap {
@@ -169,7 +169,7 @@ function finalNode(
   if (boundary === undefined || !hasInterruptionEvidence(blocks)) return undefined
   return {
     kind: 'assistant',
-    seq: boundary.seq - 0.9,
+    seq: boundary.seq + CHAT_SYNTHETIC_SEQ_OFFSETS.interruptedAssistant,
     time: boundary.time,
     turn: state.turn,
     step: state.step,

packages/client/ui-conversation/src/client/conversation-nodes/chat-snapshot-builder.ts

@@ -154,6 +154,9 @@ const EMPTY_CONTRIBUTION: LegacyContribution = {
 
 function legacyContribution(raw: ChatConversationViewNode): LegacyContribution {
   const node = raw as ChatNode
+  // Content-free settled Assistants remain in the finalized compatibility
+  // stream so StatsLine preserves its pre-assembly step counts; hidden running
+  // attempts have no final Node to contribute.
   if (raw.visibility !== 'visible' && node.kind !== 'assistant-step') return EMPTY_CONTRIBUTION
   switch (node.kind) {
     case 'user':
@@ -221,7 +224,7 @@ function sameContribution(left: LegacyContribution | undefined, right: LegacyCon
     && sameReferences(left.nodes, right.nodes)
 }
 
-/** Incremental compatibility projection retained solely for unmigrated Trajectory consumers. */
+/** Incremental compatibility projection for StatsLine and legacy top-level snapshot fields. */
 class LegacySliceBuilder {
   private readonly contributions = new Map<string, LegacyContribution>()
   private readonly finalizedContributions = new Map<string, LegacyContribution>()

packages/client/ui-conversation/src/client/conversation-nodes/common.ts

@@ -5,6 +5,16 @@ import type {
   ChatNode, ChatNodeDataMap, ChatNodeKind,
 } from '../contract/chat-nodes.ts'
 
+/**
+ * Relative positions in one durable event's seq neighborhood: interrupted
+ * Assistant, its follow-up Nodes, then follow-ups to an ordinary final.
+ */
+export const CHAT_SYNTHETIC_SEQ_OFFSETS = {
+  interruptedAssistant: -0.9,
+  interruptedFollowup: -0.8,
+  finalizedFollowup: 0.1,
+} as const
+
 /**
  * Resolve one Context's best currently loaded event Location.
  * @param context - assembled business Context.

packages/client/ui-conversation/src/client/conversation-nodes/tool.ts

@@ -5,7 +5,7 @@ import type {
 } from '@deepseek-ai/dsh-client-runtime/client'
 import { isAppendSurfaceEvent } from '@deepseek-ai/dsh-client-runtime/client'
 import type { ToolChatData } from '../contract/chat-nodes.ts'
-import { chatNode } from './common.ts'
+import { CHAT_SYNTHETIC_SEQ_OFFSETS, chatNode } from './common.ts'
 
 declare module '@deepseek-ai/dsh-client-ui-conversation/client' {
   interface ChatNodeDataMap {
@@ -190,7 +190,7 @@ function projectBlock(
     ? sameReferences(block.subCalls, children) ? block : { ...block, subCalls: children }
     : {
       kind: 'tool-result',
-      seq: interruptedAt.seq - 0.8,
+      seq: interruptedAt.seq + CHAT_SYNTHETIC_SEQ_OFFSETS.interruptedFollowup,
       time: interruptedAt.time,
       callId: block.callId,
       call: { name: block.name, argsRaw: block.argsRaw },

packages/client/ui-conversation/src/client/conversation-nodes/turn-tail.ts

@@ -7,7 +7,7 @@ import type {
   AssistantChatData, FinalAssistantChatData, TurnTailChatData,
 } from '../contract/chat-nodes.ts'
 import { deriveTurnMetrics } from '../chat/turn-metrics.ts'
-import { chatNode } from './common.ts'
+import { CHAT_SYNTHETIC_SEQ_OFFSETS, chatNode } from './common.ts'
 
 declare module '@deepseek-ai/dsh-client-ui-conversation/client' {
   interface ChatNodeDataMap {
@@ -85,7 +85,9 @@ function closingAnchor(context: ConversationNodeContext<TurnTailState>): number
     }
     if (event.type === 'assistant/message') {
       steps.set(coordinates.step, { streamedText: false, finalized: true })
-      if (hasTextAssistant(event)) anchor = event.seq + 0.1
+      if (hasTextAssistant(event)) {
+        anchor = event.seq + CHAT_SYNTHETIC_SEQ_OFFSETS.finalizedFollowup
+      }
       continue
     }
     if ((event.type as string) === 'llm/retry') {
@@ -93,7 +95,7 @@ function closingAnchor(context: ConversationNodeContext<TurnTailState>): number
       continue
     }
     if (event.type === 'step/end' && previous.streamedText && !previous.finalized) {
-      anchor = event.seq - 0.8
+      anchor = event.seq + CHAT_SYNTHETIC_SEQ_OFFSETS.interruptedFollowup
     }
   }
   return anchor