Reference the merged PR by number in the conflict comment

action.yml

@@ -52,6 +52,7 @@ runs:
         ACTION_MODE: ${{ steps.check.outputs.mode }}
         SQUASH_COMMIT: ${{ github.event.pull_request.merge_commit_sha }}
         MERGED_BRANCH: ${{ github.event.pull_request.head.ref }}
+        MERGED_PR_NUMBER: ${{ github.event.pull_request.number }}
         TARGET_BRANCH: ${{ github.event.pull_request.base.ref }}
         PR_BRANCH: ${{ github.event.pull_request.head.ref }}
       run: |

update-pr-stack.sh

@@ -45,14 +45,29 @@ has_squash_commit() {
         && git merge-base --is-ancestor SQUASH_COMMIT "$BRANCH"
 }
 
-format_branch_list_for_text() {
+# Render a conflict ref for the prose. The merged parent branch is shown as a
+# "#N" reference that GitHub links to its PR (MERGED_PR_NUMBER comes straight
+# from the event payload); the pre-squash trunk state is a bare commit with no
+# PR, so it stays in backticks. The bash recipe still uses the raw ref, which
+# `git merge` needs.
+format_conflict_ref_for_text() {
+    local ref="$1"
+    if [[ "$ref" == "origin/$MERGED_BRANCH" && -n "${MERGED_PR_NUMBER:-}" ]]; then
+        printf '#%s' "$MERGED_PR_NUMBER"
+    else
+        printf '`%s`' "$ref"
+    fi
+}
+
+format_conflict_list_for_text() {
+    local separator
     for ((i=1; i<=$#; i++)); do
         case $i in
-            1) format='`%s`';;
-            $#) format=', and `%s`';;
-            *) format=', `%s`';;
+            1) separator='';;
+            $#) separator=', and ';;
+            *) separator=', ';;
         esac
-        printf "$format" "${!i}"
+        printf '%s%s' "$separator" "$(format_conflict_ref_for_text "${!i}")"
     done
 }
 
@@ -107,7 +122,7 @@ update_direct_target() {
             echo "### ⚠️ Automatic update blocked by merge conflicts"
             echo
             echo -n "I tried to merge "
-            format_branch_list_for_text "${CONFLICTS[@]}"
+            format_conflict_list_for_text "${CONFLICTS[@]}"
             echo " into this branch while updating the pull request stack and hit conflicts."
             echo
             echo "#### How to resolve"
@@ -196,13 +211,13 @@ continue_after_resolution() {
     echo "Current base branch: $OLD_BASE"
 
     # The synchronize payload is the child PR, so SQUASH_COMMIT / MERGED_BRANCH /
-    # TARGET_BRANCH from the original squash-merge run are not in the environment.
-    # Reconstruct them from the merged parent PR: OLD_BASE is the parent branch,
-    # and the merged PR whose head is OLD_BASE gives the new target (its base) and
-    # the squash commit (its merge commit).
-    local NEW_TARGET SQUASH_HASH
-    read -r NEW_TARGET SQUASH_HASH < <(gh pr list --head "$OLD_BASE" --state merged \
-        --json baseRefName,mergeCommit --jq '.[0] | "\(.baseRefName // "") \(.mergeCommit.oid // "")"')
+    # TARGET_BRANCH / MERGED_PR_NUMBER from the original squash-merge run are not
+    # in the environment. Reconstruct them from the merged parent PR: OLD_BASE is
+    # the parent branch, and the merged PR whose head is OLD_BASE gives the new
+    # target (its base), the squash commit (its merge commit), and its number.
+    local NEW_TARGET SQUASH_HASH MERGED_PR_NUMBER
+    read -r NEW_TARGET SQUASH_HASH MERGED_PR_NUMBER < <(gh pr list --head "$OLD_BASE" --state merged \
+        --json baseRefName,mergeCommit,number --jq '.[0] | "\(.baseRefName // "") \(.mergeCommit.oid // "") \(.number // "")"')
 
     if [[ -z "$NEW_TARGET" || -z "$SQUASH_HASH" ]]; then
         echo "⚠️ Could not find where '$OLD_BASE' was merged to; skipping base branch and deletion updates"