graph TD A[Start Subagent 5: Combine Multiple Avatar Angles] --> B[Validate Input Files] B --> C{Check All Files Present} C -->|Missing Files| D[Error: Request Missing Files] D --> B C -->|All Files Present| E[Load MP4 URLs] E --> F[Initialize Skill #173] F --> G[Input MP4 URLs in Sequence] G --> H{Concatenation Process} H -->|Success| I[Save Combined MP4] H -->|Failure| J[Error: Retry Concatenation] J --> F I --> K[Verify Output File] K --> L{Quality Check} L -->|Pass| M[Output: combined-newsreader-angles] L -->|Fail| N[Error: Quality Issues] N --> F M --> O[End Subagent 5]