[Fix] Thinking headings run together in task transcripts

apps/web/src/app/(sandbox)/task/[taskId]/hooks/services/acp-protocol-service.ts

@@ -21,6 +21,7 @@ import {
   getImageUrisFromContentBlocks,
   getProviderRetryNoticeFromMessageData,
   inferAcpMessageKind,
+  normalizeAcpReasoningText,
   normalizeTranscriptUserText,
   normalizePlanPayload,
   parseAcpRequestUserInputPayload,
@@ -317,6 +318,8 @@ export function toAcpUiMessage(
     case 'reasoning':
       return {
         ...base,
+        text: normalizeAcpReasoningText(normalized.text ?? ''),
+        rawText: normalized.text ?? '',
         role: 'assistant',
         kind: 'reasoning',
         data: payloadRecord,
@@ -1281,10 +1284,23 @@ export class AcpProtocolService {
         const existing = messages[idx]! as AcpOtherUiMessage;
         const next = messages.slice();
 
+        const existingText = existing.rawText ?? existing.text ?? '';
+        const candidateText = candidate.rawText ?? candidate.text ?? '';
+        const hasOverlappingBoldBoundary =
+          idPrefix === 'reasoning' &&
+          existingText.endsWith('**') &&
+          candidateText.startsWith('****');
+        const combinedText =
+          existingText +
+          (hasOverlappingBoldBoundary ? candidateText.slice(2) : candidateText);
         next[idx] = {
           ...existing,
           ts: event.ts,
-          text: (existing.text ?? '') + (candidate.text ?? ''),
+          text:
+            idPrefix === 'reasoning'
+              ? normalizeAcpReasoningText(combinedText)
+              : combinedText,
+          ...(idPrefix === 'reasoning' ? { rawText: combinedText } : {}),
           partial: true,
           data: event.payload,
         };

apps/web/src/app/(sandbox)/task/[taskId]/messages/acp/types.ts

@@ -55,6 +55,8 @@ export interface AcpTodoSectionUiMessage extends AcpUiMessageBase {
 export interface AcpOtherUiMessage extends AcpUiMessageBase {
   kind: Exclude<AcpMessageKind, 'tool_call' | 'tool_result' | 'plan'>;
   data: Record<string, unknown>;
+  /** Source chunks before reasoning-only display normalization. */
+  rawText?: string;
 }
 
 export type AcpUiMessage =

apps/worker/src/sandbox-server/lib/harnesses/opencode-server/harness.ts

@@ -10,6 +10,7 @@ import {
   asRecord,
   asString,
   buildAcpRequestUserInputRequestId,
+  normalizeAcpReasoningText,
   parseAcpFlattenedMcpToolName,
   OPENCODE_ARCHITECT_AGENT,
   OPENCODE_BUILD_AGENT,
@@ -607,11 +608,13 @@ function extractAssistantText(message: OpenCodeSessionMessage): string {
 }
 
 function extractAssistantReasoning(message: OpenCodeSessionMessage): string {
-  return message.parts
-    .filter((part) => part.type === 'reasoning')
-    .map(extractPartText)
-    .filter((text) => text.length > 0)
-    .join('\n');
+  return normalizeAcpReasoningText(
+    message.parts
+      .filter((part) => part.type === 'reasoning')
+      .map(extractPartText)
+      .filter((text) => text.length > 0)
+      .join('\n'),
+  );
 }
 
 function parseOpenCodeMessageRole(value: unknown): OpenCodeMessageRole | null {

packages/types/src/acp.ts

@@ -53,6 +53,25 @@ export type AcpLiveEventType =
 /** All known Roomote runtime event types — envelope (persisted) + live-only (streamed). */
 export type AcpEventType = AcpEnvelopeEventType | AcpLiveEventType;
 
+/** Restore separation between bold reasoning headings concatenated by a provider. */
+export function normalizeAcpReasoningText(text: string): string {
+  return text.replace(/[^\r\n]+/g, (line) => {
+    if (!line.startsWith('**') || !line.endsWith('**')) {
+      return line;
+    }
+
+    const headings = line.slice(2, -2).split('****');
+    if (
+      headings.length < 2 ||
+      headings.some((heading) => heading.length === 0 || heading.includes('**'))
+    ) {
+      return line;
+    }
+
+    return `**${headings.join('**\n\n**')}**`;
+  });
+}
+
 export const ACP_LOGICAL_EVENT_ID_KEY = 'logicalEventId' as const;
 
 export interface AcpLogicalEventIdParts {