Method failAgentTaskTerminally

src/node/services/taskService.ts:8504–8584

* Terminal settlement for a child task whose stream failed with a * non-retryable error: mark interrupted with a descriptive launch error, * persist a durable failure artifact in every ancestor session dir (so * background children, restarts, and post-cleanup task_awaits observe the * ty

(
    workspaceId: string,
    entry: { projectPath: string; workspace: WorkspaceConfigEntry },
    failure: { errorType: string; errorMessage: string }
  )

   * typed failure), then reject pending waiters with the failure message.
   */
  private async failAgentTaskTerminally(
    workspaceId: string,
    entry: { projectPath: string; workspace: WorkspaceConfigEntry },
    failure: { errorType: string; errorMessage: string }
  ): Promise<void> {
    assert(workspaceId.length > 0, "failAgentTaskTerminally: workspaceId must be non-empty");
    assert(
      failure.errorMessage.length > 0,
      "failAgentTaskTerminally: errorMessage must be non-empty"
    );

    await this.editWorkspaceEntry(
      workspaceId,
      (ws) => {
        ws.taskStatus = "interrupted";
        ws.taskLaunchError = failure.errorMessage;
      },
      { allowMissing: true }
    );
    await this.emitWorkspaceMetadata(workspaceId);

    const parentWorkspaceId = entry.workspace.parentWorkspaceId;
    if (parentWorkspaceId) {
      const cfg = this.config.loadConfigOrDefault();
      const index = this.buildAgentTaskIndex(cfg);
      const ancestorWorkspaceIds = this.listAncestorWorkspaceIdsUsingParentById(
        index.parentById,
        workspaceId
      );
      const workflowOwnedAncestorWorkspaceIds = ancestorWorkspaceIds.filter(
        (ancestorWorkspaceId) =>
          this.getWorkflowOwnedDescendantAgentTaskUsingIndex(
            index,
            ancestorWorkspaceId,
            workspaceId
          ) === true
      );

      const persistedAtMs = Date.now();
      for (const ancestorWorkspaceId of ancestorWorkspaceIds) {
        try {
          await upsertSubagentFailureArtifact({
            workspaceId: ancestorWorkspaceId,
            workspaceSessionDir: this.config.getSessionDir(ancestorWorkspaceId),
            childTaskId: workspaceId,
            parentWorkspaceId,
            ancestorWorkspaceIds,
            workflowOwnedAncestorWorkspaceIds,
            errorType: failure.errorType,
            errorMessage: failure.errorMessage,
            model: entry.workspace.taskModelString,
            nowMs: persistedAtMs,
          });
        } catch (error: unknown) {
          log.error("Failed to persist subagent failure artifact", {
            workspaceId: ancestorWorkspaceId,
            childTaskId: workspaceId,
            error,