diff --git a/action.yml b/action.yml
index e00e6ea..ba4f8b9 100644
--- a/action.yml
+++ b/action.yml
@@ -22,7 +22,7 @@ inputs:
 
   pr_comments_url:
     description: "PR comments URL (GitHub or Gitea)"
-    required: true
+    required: false
 
   pr_comment_id:
     description: "Existing PR comment ID if updating"
diff --git a/tf-pr-comment.sh b/tf-pr-comment.sh
index 093ff0d..29e63c9 100644
--- a/tf-pr-comment.sh
+++ b/tf-pr-comment.sh
@@ -12,7 +12,7 @@ PR_COMMENT_ID="${PR_COMMENT_ID:-}"
 PR_COMMENT_URI="${PR_COMMENT_URI:-}"
 GITHUB_TOKEN="${GITHUB_TOKEN:-}"
 
-# === Validate required inputs ========================================
+# === Validate inputs =================================================
 if [[ -z "$COMMENTER_TYPE" ]]; then
   echo "❌ commenter_type is required."
   exit 1
@@ -24,7 +24,7 @@ if [[ -z "$GITHUB_TOKEN" ]]; then
 fi
 
 # === Move into working directory if specified ========================
-if [[ -n "$WORKING_DIR" && "$WORKING_DIR" != "0" ]]; then
+if [[ -n "$WORKING_DIR" ]]; then
   TARGET_DIR="${GITHUB_WORKSPACE}/${WORKING_DIR}"
   if [[ ! -d "$TARGET_DIR" ]]; then
     echo "❌ Error: Cannot change to working directory '${WORKING_DIR}'"
@@ -33,7 +33,6 @@ if [[ -n "$WORKING_DIR" && "$WORKING_DIR" != "0" ]]; then
   echo "🔹 Changing to working directory: $WORKING_DIR"
   cd "$TARGET_DIR"
 else
-  echo "⚠️  Detected empty or numeric working_dir ('${WORKING_DIR:-unset}'); treating as unset."
   cd "${GITHUB_WORKSPACE:-.}"
 fi
 
@@ -68,12 +67,33 @@ ${COMMENTER_INPUT}
 ${EXIT_STATUS_MSG}
 "
 
-# === Post Comment ====================================================
+# === Determine PR_COMMENTS_URL if missing ===========================
 if [[ -z "$PR_COMMENTS_URL" ]]; then
-  echo "❌ Missing PR_COMMENTS_URL environment variable."
-  exit 1
+  echo "⚠️ PR_COMMENTS_URL not provided, attempting to generate..."
+
+  if [[ -n "$GITEA_API_URL" && -n "$GITEA_REPOSITORY" && -n "$GITEA_PULL_REQUEST_ID" ]]; then
+    PR_COMMENTS_URL="${GITEA_API_URL}/repos/${GITEA_REPOSITORY}/issues/${GITEA_PULL_REQUEST_ID}/comments"
+    PR_COMMENT_URI="${GITEA_API_URL}/repos/${GITEA_REPOSITORY}/issues/comments"
+    echo "✅ Generated Gitea PR_COMMENTS_URL: $PR_COMMENTS_URL"
+
+  elif [[ -n "$GITHUB_EVENT_PATH" && -f "$GITHUB_EVENT_PATH" ]]; then
+    PR_NUMBER=$(jq -r ".pull_request.number" "$GITHUB_EVENT_PATH")
+    if [[ "$PR_NUMBER" != "null" ]]; then
+      PR_COMMENTS_URL=$(jq -r ".pull_request.comments_url" "$GITHUB_EVENT_PATH")
+      PR_COMMENT_URI=$(jq -r ".repository.issue_comment_url" "$GITHUB_EVENT_PATH" | sed "s|{/number}||g")
+      echo "✅ Generated GitHub PR_COMMENTS_URL: $PR_COMMENTS_URL"
+    else
+      echo "❌ Not a pull request. Cannot generate PR_COMMENTS_URL."
+      exit 0
+    fi
+
+  else
+    echo "❌ Cannot determine PR_COMMENTS_URL automatically. Please provide it as input."
+    exit 1
+  fi
 fi
 
+# === Post Comment ====================================================
 if [[ -n "$PR_COMMENT_ID" && -n "$PR_COMMENT_URI" ]]; then
   echo "🌀 Updating existing comment (ID: ${PR_COMMENT_ID})"
   curl -sS -X PATCH \