Proposal for (partial) template includes

gistfile1.json5

{  
  include_template: "a",  // <-- full template, used as a base 
  is_video: {  
    use: ":original",
    robot: "/file/filter",
    accepts: [  
      [  
        "${file.mime}",
        "regex",
        "video"
      ],
    ],
    error_on_decline:false
  },
  is_image: {  
    use: ":original",
    robot: "/file/filter",
    accepts: [  
      [  
        "${file.mime}",
        "regex",
        "image",
      ],
    ],
    error_on_decline: false
  },
  include_template_partial: "c.video_encode", // <-- include just 1 named step
  video_encode: {
    use: "is_video", // <-- override its `use` parameter to connect the chain
  },
  include_template_partial: "c.image_resize",
  image_resize: {
    use: "is_image",
  },
  store: { // <-- was already inside template "a"
    // <-- override its `use` parameter to connect the chain
    use: ["video_encode", "image_resize", ":original"],
  },
}

@Prinzhorn I see where the two diverge now, your approach is interesting and easier to add indeed. I'll discuss with the team if I'm not overlooking anything.