[Feature Request] GraphQL API to retroactively link merged PRs to closed issues in Projects V2

[joaodotwork]

Problem

Currently, the LINKED_PULL_REQUESTS field in Projects V2 is automatically populated only when:

• "Closes #XX" keywords are present in PR descriptions before the PR is merged
• Branches are linked to issues via gh issue develop or createLinkedBranch mutation

Once a PR is merged and an issue is closed, there is no way to retroactively create this development link metadata. This creates problems for:

1. Historical project organization - Teams migrating to Projects V2 cannot properly link their existing merged PRs to closed issues
2. Post-merge corrections - If a PR was merged without proper "Closes #XX" keywords, the metadata cannot be fixed
3. Bulk operations - When reorganizing or auditing projects, there's no way to batch-create development links

Current Workarounds and Limitations

I've investigated all available options:

❌ updateProjectV2ItemFieldValue mutation

updateProjectV2ItemFieldValue(input: {
  projectId: "..."
  itemId: "..."
  fieldId: "PVTF_..."  # LINKED_PULL_REQUESTS field
  value: { linkedPullRequestIds: [...] }  # NOT SUPPORTED
})

Result: InputObject 'ProjectV2FieldValue' doesn't accept argument 'linkedPullRequestIds'

❌ createLinkedBranch mutation

• Only creates branch-to-issue links
• Requires a commit oid parameter
• Cannot link existing PRs

❌ Timeline/Connected Events API

• Read-only
• No POST endpoint available
• Cannot create CONNECTED_EVENT or CLOSED_EVENT retroactively

⚠️ Current Best Option (Insufficient)

Adding comments like "Closed by #XX" creates visual cross-references but does not populate the Projects V2 metadata field.

Proposed Solution

Add a new GraphQL mutation or extend existing ones to support retroactive development linking:

Option 1: New Mutation

mutation {
  linkPullRequestToIssue(input: {
    pullRequestId: "PR_kwDO..."
    issueId: "I_kwDO..."
    relationship: CLOSES  # or REFERENCES, MENTIONS
  }) {
    pullRequest { id }
    issue {
      id
      projectItems(first: 10) {
        nodes {
          fieldValues(first: 10) {
            nodes {
              ... on ProjectV2ItemFieldPullRequestValue {
                pullRequests { totalCount }
              }
            }
          }
        }
      }
    }
  }
}

Option 2: Extend Existing Mutation

mutation {
  updateProjectV2ItemFieldValue(input: {
    projectId: "PVT_kwHO..."
    itemId: "PVTI_lAHO..."  # Issue item in project
    fieldId: "PVTF_lAHO..."  # LINKED_PULL_REQUESTS field ID
    value: {
      linkedPullRequestIds: ["PR_kwDO...", "PR_kwDO..."]
    }
  }) {
    projectV2Item { id }
  }
}

Use Cases

1. Project Migrations: Teams moving to Projects V2 want to preserve historical PR-to-issue relationships
2. Post-Merge Corrections: Developers forgot "Closes #XX" and want to fix the metadata after merge
3. Bulk Audits: Organizations reviewing closed issues and linking them to PRs that actually resolved them
4. Documentation: Creating proper development trails for compliance or historical reference

Expected Behavior

After linking:

• The issue's Projects V2 item should show the PR in the "Linked pull requests" field
• The PR should appear in the issue's timeline as a proper development connection (not just a comment reference)
• Queries filtering by linkedPullRequests should include retroactively linked PRs

Additional Context

I discovered this limitation while trying to properly organize a project's migration roadmap where multiple PRs (#66, #67, #68) closed multiple issues (#53-#59, #62-#63). All PRs included "Closes #XX" in their descriptions, but because they were merged before I realized the keywords needed to be present earlier, the Projects V2 metadata was never populated.

References

• Projects V2 field types: LINKED_PULL_REQUESTS (read-only)
• Related mutation: createLinkedBranch (only for branches)
• Current workaround: Comment-based cross-references (insufficient)

---

Would love to see this capability added to the GraphQL API to support better project organization and historical accuracy!

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