Checked how gh-stack extension works, and additional to the usual "base of each PR points to parent", they have created and additional endpoint to notify github of the stack components:

⏺ gh-stack uses two complementary mechanisms:                                                         
                                                                                                      
  1. PR Base Branch Targeting (the foundation)                                                         
                                                                                             
  Each PR's base is set to the previous PR's head branch, forming a chain:                             
                                                                                                       
  main                                                                                                 
    └─ branch-1 → PR #1 (base: main)                                                                   
         └─ branch-2 → PR #2 (base: branch-1)                                                          
              └─ branch-3 → PR #3 (base: branch-2)                                                     
                                                                                                       
  This is what makes GitHub show the correct diff (only changes from that slice of work, not the whole 
  stack).                                                                                              
                                                                                                       
  2. GitHub's Native Stacks API (the registration)                                                     
              
  After PRs are created, the tool registers the stack with GitHub's dedicated (private-preview) REST   
  endpoint:                                                                                            
                                                                                                       
  POST /repos/{owner}/{repo}/cli_internal/pulls/stacks                                                 
  Body: { "pull_request_numbers": [101, 102, 103] }
                                                                                                       
  GitHub validates that the PRs actually form a valid base→head chain and returns a stackID. This is   
  what enables the native stack UI on GitHub.                                                          
                                                                                                       
  The relevant code is in internal/github/github.go — look for CreateStack, UpdateStack, DeleteStack,  
  and ListStacks.
                                                                                                       
  Local state                                                                                     
              
  A .git/gh-stack JSON file (not committed) tracks which branches belong to the stack, their ordering, 
  the server-assigned stackID, and per-branch HEAD SHAs for rebase tracking.

It would be really great if graphite could call this api to leverage github stacks UI, and

gt

can also create the local state

gh-stack

needs so they can coexist.

Thanks Guillermo! Appreciate you digging into how gh-stack works under the hood. We're aware GitHub is building out native stacks support and we're keeping a close eye on it as the API matures past private preview. Integrating with it so Graphite stacks show up in GitHub's native UI is something we'd consider once the API stabilizes. I've captured this with the technical detail you provided. Thanks for putting it on our radar so thoroughly! 🙏