issues reply fails: CommentCreateInput missing issueId (Argument Validation Error)

[jjuraszek]

Summary

linearis issues reply <root-thread-id> --body "..." always fails with a GraphQL validation error. The reply mutation builds a CommentCreateInput with only parentId + body, omitting the parent entity id (issueId/projectId/initiativeId) that Linear requires even on threaded replies.

Repro

linearis issues reply f94ee0d6-b8d1-4f84-82c3-87076c40ede0 --body "hello"

Actual

{
  "error": "GraphQL request failed: Argument Validation Error - Exactly one of projectUpdateId, initiativeUpdateId, postId, documentContentId, projectId, initiativeId or issueId must be defined."
}

issues discuss (root comment) works fine, because startIssueDiscussion passes issueId. Only the reply path is broken.

Root cause

dist/services/discussion-service.js -> replyToDiscussion:

export async function replyToDiscussion(client, input) {
    await assertRootDiscussionThread(client, input.threadId, input.entityKind);
    const result = await client.request(StartDiscussionDocument, {
        input: {
            parentId: input.threadId,   // no entity id alongside parentId
            body: input.body,
        },
    });
    ...
}

Linear's CommentCreateInput requires exactly one entity id (issueId etc.) in addition to parentId for a threaded reply. The CLI sends only parentId.

Suggested fix (low effort - the data is already fetched)

assertRootDiscussionThread already returns the comment via GetDiscussionCommentContext, which selects issueId, projectId, and initiativeId. Capture its return value and forward the entity id:

export async function replyToDiscussion(client, input) {
    const thread = await assertRootDiscussionThread(client, input.threadId, input.entityKind);
    const result = await client.request(StartDiscussionDocument, {
        input: {
            parentId: input.threadId,
            issueId: thread.issueId ?? undefined,
            projectId: thread.projectId ?? undefined,
            initiativeId: thread.initiativeId ?? undefined,
            body: input.body,
        },
    });
    ...
}

No extra network call needed - the context query already returns all three ids. Same applies to project/initiative reply paths.

Version

linearis 2026.4.9

[linear]

LIN-153

[iamfj]

Thanks for the detailed report and the fix in #227 — forwarding the parent entity id (issueId/projectId/initiativeId) on threaded replies so they stop hitting the "Exactly one of … must be defined" validation error. This is now rolled out on the prerelease channel (npm i -g linearis@next, currently 2026.6.0-next.5) — would love if you could confirm it on your end. Planning to promote it to stable soon (#231). Happy for any feedback!