feat(#2471): post failing config deploy build log to the config pr

hive-c0re/src/forge/mod.rs

@@ -10,8 +10,8 @@ mod repos;
 mod users;
 
 pub use pr_merge::{
-    ForgeMergeError, config_repo, fetch_pr_head_into_applied, merge_config_pr_ff, pr_head_sha,
-    pr_is_open,
+    ForgeMergeError, config_repo, fetch_pr_head_into_applied, merge_config_pr_ff, post_pr_comment,
+    pr_head_sha, pr_is_open,
 };
 pub use repos::{
     create_agent_repo, ensure_config_repo, ensure_knowledge_repo, ensure_meta_remote, ensure_repo,

hive-c0re/src/forge/pr_merge.rs

@@ -218,6 +218,38 @@ pub async fn merge_config_pr_ff(repo: &str, pr: u64, sha: &str) -> Result<(), Fo
     }
 }
 
+/// Post a comment to PR (= issue) `pr` on `repo` as the core forge user.
+/// PRs are issues in Forgejo, so the PR number is the issue index. Used to
+/// surface a failed config-approval deploy's build log back onto the PR so
+/// the manager sees why it was rejected without leaving the forge. `repo`
+/// is `owner/name`.
+///
+/// # Errors
+/// `Other` on absent core token, malformed repo, or transport/API failure.
+pub async fn post_pr_comment(repo: &str, pr: u64, body: &str) -> Result<(), ForgeMergeError> {
+    let token = core_token()
+        .ok_or_else(|| ForgeMergeError::Other(anyhow::anyhow!("forge core token absent")))?;
+    let (owner, name) = repo.split_once('/').ok_or_else(|| {
+        ForgeMergeError::Other(anyhow::anyhow!("forge repo `{repo}` is not owner/name"))
+    })?;
+    let index = i64::try_from(pr)
+        .map_err(|_| ForgeMergeError::Other(anyhow::anyhow!("PR index {pr} overflows i64")))?;
+    let client = api(&token).map_err(ForgeMergeError::Other)?;
+    client
+        .issue_create_comment(
+            owner,
+            name,
+            index,
+            forgejo_api::structs::CreateIssueCommentOption {
+                body: body.to_owned(),
+                updated_at: None,
+            },
+        )
+        .await
+        .map_err(|e| ForgeMergeError::Other(anyhow::Error::from(e).context("post PR comment")))?;
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::repo_agent_name;