diff --git a/src/plane_sync.py b/src/plane_sync.py
index ad88e9e..da2412d 100644
--- a/src/plane_sync.py
+++ b/src/plane_sync.py
@@ -113,25 +113,26 @@ def find_issue_id(work_item_id: str, project_id: str = None) -> str | None:
         resp.raise_for_status()
         data = resp.json()
         results = data.get("results", data if isinstance(data, list) else [])
+        # M-6: match by sequence_id directly (the authoritative per-project
+        # number), parsed from the work_item_id suffix - no hardcoded prefix.
+        try:
+            target_num = int(work_item_id.rsplit("-", 1)[1])
+        except (IndexError, ValueError):
+            target_num = None
         for issue in results:
-            seq = issue.get("sequence_id")
-            identifier = f"ET-{seq:03d}" if seq else ""
-            if identifier == work_item_id or work_item_id in issue.get("name", ""):
+            if target_num is not None and issue.get("sequence_id") == target_num:
                 return issue["id"]
-        # Fallback: get all issues and match by sequence_id number
-        if work_item_id.startswith("ET-"):
-            try:
-                target_num = int(work_item_id.split("-")[1])
-            except (IndexError, ValueError):
-                target_num = None
-            if target_num:
-                resp2 = httpx.get(url, headers=PLANE_HEADERS, timeout=10)
-                resp2.raise_for_status()
-                data2 = resp2.json()
-                results2 = data2.get("results", data2 if isinstance(data2, list) else [])
-                for issue in results2:
-                    if issue.get("sequence_id") == target_num:
-                        return issue["id"]
+            if work_item_id in issue.get("name", ""):
+                return issue["id"]
+        # Fallback: get all issues and match by sequence_id number (any prefix)
+        if target_num is not None:
+            resp2 = httpx.get(url, headers=PLANE_HEADERS, timeout=10)
+            resp2.raise_for_status()
+            data2 = resp2.json()
+            results2 = data2.get("results", data2 if isinstance(data2, list) else [])
+            for issue in results2:
+                if issue.get("sequence_id") == target_num:
+                    return issue["id"]
     except Exception as e:
         logger.error(f"Failed to find issue for {work_item_id}: {e}")
     return None