diff --git a/.github/workflows/pg-compat-matrix.yml b/.github/workflows/pg-compat-matrix.yml
index 71c4dbd..55c4d14 100644
--- a/.github/workflows/pg-compat-matrix.yml
+++ b/.github/workflows/pg-compat-matrix.yml
@@ -43,5 +43,5 @@ jobs:
 
       - name: Run PostgreSQL compatibility smoke checks
         env:
-          PG_DSN: postgresql://postgres:postgres@127.0.0.1:5432/compatdb?sslmode=disable
+          PG_DSN_CANDIDATES: postgresql://postgres:postgres@postgres:5432/compatdb?sslmode=disable,postgresql://postgres:postgres@127.0.0.1:5432/compatdb?sslmode=disable
         run: python backend/scripts/pg_compat_smoke.py
diff --git a/README.md b/README.md
index ff4bc85..dccac4f 100644
--- a/README.md
+++ b/README.md
@@ -106,6 +106,13 @@ PG_DSN='postgresql://postgres:postgres@127.0.0.1:5432/compatdb?sslmode=disable'
 python backend/scripts/pg_compat_smoke.py
 ```
 
+CI/runner-safe variant (tries multiple hosts):
+
+```bash
+PG_DSN_CANDIDATES='postgresql://postgres:postgres@postgres:5432/compatdb?sslmode=disable,postgresql://postgres:postgres@127.0.0.1:5432/compatdb?sslmode=disable' \
+python backend/scripts/pg_compat_smoke.py
+```
+
 ## Environment variables reference
 
 All variables are defined in `.env.example`.
diff --git a/backend/scripts/pg_compat_smoke.py b/backend/scripts/pg_compat_smoke.py
index 14facab..8d953d3 100644
--- a/backend/scripts/pg_compat_smoke.py
+++ b/backend/scripts/pg_compat_smoke.py
@@ -31,13 +31,39 @@ async def _fetchrow_required(conn: asyncpg.Connection, query: str, label: str) -
     return dict(row)
 
 
+def _dsn_candidates() -> list[str]:
+    # Preferred: explicit candidate list for CI portability (Gitea/GitHub runners).
+    raw_candidates = os.getenv("PG_DSN_CANDIDATES", "").strip()
+    if raw_candidates:
+        values = [item.strip() for item in raw_candidates.split(",") if item.strip()]
+        if values:
+            return values
+    # Backward compatible single DSN.
+    raw_single = os.getenv("PG_DSN", "").strip()
+    if raw_single:
+        return [raw_single]
+    raise RuntimeError("Missing PG_DSN or PG_DSN_CANDIDATES")
+
+
 async def run() -> None:
-    dsn = _required_env("PG_DSN")
-    conn = await _connect_with_retry(dsn)
+    candidates = _dsn_candidates()
+    last_error: Exception | None = None
+    conn: asyncpg.Connection | None = None
+    used_dsn = ""
+    for dsn in candidates:
+        try:
+            conn = await _connect_with_retry(dsn)
+            used_dsn = dsn
+            break
+        except Exception as exc:
+            last_error = exc
+    if conn is None:
+        raise RuntimeError(f"Could not connect to PostgreSQL using candidates: {last_error}")
+
     try:
         version = await conn.fetchval("SHOW server_version")
         current_db = await conn.fetchval("SELECT current_database()")
-        print(f"[compat] Connected: version={version} db={current_db}")
+        print(f"[compat] Connected: version={version} db={current_db} dsn={used_dsn}")
 
         # Core collector queries
         await _fetchrow_required(