Fix add_comment to respect append-only-comments from messages config

[Copilot]

The add_comment handler was hiding older comments when hide-older-comments was enabled, even when the global append-only-comments: true was set in messages config. This created a conflict where campaign workflows configured for append-only timeline behavior would still minimize previous comments.

Changes

• add_comment.cjs: Check global appendOnlyComments flag from messages config and skip hiding when enabled
• add_comment.test.cjs: Add test coverage for append-only behavior interaction

Implementation

// Check global messages config during handler initialization
const messagesConfig = getMessages();
const appendOnlyComments = messagesConfig?.appendOnlyComments === true;

// Skip hiding when append-only mode is active
if (hideOlderCommentsEnabled && !appendOnlyComments && workflowId) {
  await hideOlderComments(github, repoParts.owner, repoParts.repo, itemNumber, workflowId, isDiscussion);
} else if (hideOlderCommentsEnabled && appendOnlyComments) {
  core.info("Skipping hide-older-comments because append-only-comments is enabled");
}

The fix ensures campaign workflows using append-only-comments: true maintain a complete comment timeline regardless of individual handler configurations.

Original prompt

Fix add_comment not being added as a new comment even though we used appendCommentOnly in campaign generator, see generated comments on issue: https://github.com/githubnext/gh-aw/issues/11170

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