{"record":{"id":"358fe5dac518186d","repo":"deepseek-ai/deepseek-harness","slug":"fork-child-rename-failed-renamed-error-code","errorCode":null,"errorMessage":"fork child rename failed: ${renamed.error.code}: ${renamed.error.message}","messagePattern":"fork child rename failed: (.+?): (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"packages/client/runtime/src/client/sessions/service.ts","lineNumber":529,"sourceCode":"  }): Promise<SessionId> {\n    const sourceTitle = opts.increaseTitle\n      ? this.list.getSnapshot().byId[opts.sessionId]?.title\n      : undefined\n    const result = await this.manager.fork({\n      sessionId: opts.sessionId,\n      // Flooring lands inside the anchor's own turn (every turn opens with a\n      // turn/start), so the host's first-turn/end-at-or-after cut still ends\n      // on that turn — never clipped back to the previous one.\n      ...(opts.atSeq === undefined ? {} : { atSeq: Math.floor(opts.atSeq) }),\n    })\n    if (!result.ok) throw new SessionForkError(result.error, opts.sessionId)\n    this.projectList()\n    const childId = result.value.sessionId\n    if (sourceTitle !== undefined) {\n      const child = this.binding(childId)?.session\n      if (child === undefined) throw new Error(`fork child \"${childId}\" is not locally addressable`)\n      const renamed = await child.rename(increasedForkTitle(sourceTitle))\n      if (!renamed.ok) throw new Error(`fork child rename failed: ${renamed.error.code}: ${renamed.error.message}`)\n    }\n    return childId\n  }\n\n  /**\n   * Resolve an Agent-scoped context view (use-and-discard).\n   * @param id - session id (the agent identity — 1:1 same axis).\n   * @returns scoped ctx, or undefined for a session neither listed nor already scoped.\n   */\n  scope(id: SessionId): AgentContext | undefined {\n    return this.resolve(id)?.ctx\n  }\n\n  /**\n   * Read the Agent scope tag off a context. Service-method boundary: fetch\n   * bundles must reach scope resolution through ctx.sessions — a cross-bundle\n   * value import of the standalone helper would inline a second module\n   * instance whose private tag Symbol never matches.","sourceCodeStart":511,"sourceCodeEnd":547,"githubUrl":"https://github.com/deepseek-ai/deepseek-harness/blob/b150a551b8d465e31e418e1b2eaf5e79bbb7d28e/packages/client/runtime/src/client/sessions/service.ts#L511-L547","documentation":"The fork RPC succeeded and the child session exists, but the follow-up step — renaming the child to the increased fork title derived from the source title — returned a failed Result, so fork() throws instead of returning the child id. The thrown error embeds the rename RpcError's code and message. This is a partial failure: the child session is created and usable; only the automatic title bump was lost, and the caller loses the return value unless it preallocated the child id.","triggerScenarios":"await sessions.fork(sourceId, ...) where the source has a title (sourceTitle !== undefined triggers the rename), the freshly created child is locally addressable, but child.rename(increasedForkTitle(sourceTitle)) fails host-side — rename validation, a lock on the new session, or connection state changing between create and rename.","commonSituations":"Connection flapping or host load between the fork and rename calls; title validation rejecting the generated incremented title; concurrent operations grabbing the freshly created child.","solutions":["Recover instead of retrying the fork: the child exists — find it by your preallocated sessionId (or as the newest session) and rename it manually or accept the default title","Preallocate the child id via opts.sessionId so a rename failure never orphans the child","Retry only the rename step once the host confirms the child session","Report the embedded code and message — they name the rename refusal, not a fork problem"],"exampleFix":"// before\nconst childId = await sessions.fork(sourceId, { atSeq })\n\n// after — preallocate so a failed title bump is recoverable\nconst sessionId = mintSessionId()\nlet childId: SessionId\ntry {\n  childId = await sessions.fork(sourceId, { atSeq, sessionId })\n} catch (error) {\n  if (error instanceof Error && error.message.startsWith('fork child rename failed')) {\n    childId = sessionId // fork succeeded; only the derived title was not applied\n  } else {\n    throw error\n  }\n}","handlingStrategy":"fallback","validationCode":null,"typeGuard":null,"tryCatchPattern":"try {\n  childId = await sessions.fork(sourceId, { atSeq, sessionId })\n} catch (error) {\n  if (error instanceof Error && error.message.startsWith('fork child rename failed')) {\n    childId = sessionId // keep the preallocated id; rename later or accept the default title\n  } else {\n    throw error\n  }\n}","preventionTips":["Always pass opts.sessionId when forking if you need to recover from post-create steps","Treat this error as non-fatal: the child session exists and is fully usable","Check the embedded rename RpcError code before deciding to retry the rename"],"tags":["session-fork","rename","partial-failure","rpc"],"backgroundTag":"partial-operation-failure","analyzedSha":"b150a551b8d465e31e418e1b2eaf5e79bbb7d28e","analyzedAt":"2026-08-24T18:12:29.105Z","schemaVersion":2},"datasetVersion":"2026-08-24T22:17:12.610Z"}