diff --git a/.gitignore b/.gitignore
index e3b9d87..6b6376c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +1,9 @@
 # Nix devshell artefacts
-/.postgres/
-/.direnv/
+.postgres/
+.direnv/
 result
 result-*
 
 # Process-compose state
-/.pc.*
+.pc.*
 process-compose-*.log
diff --git a/flake.nix b/flake.nix
index 6725942..fb42a49 100644
--- a/flake.nix
+++ b/flake.nix
@@ -27,7 +27,11 @@
           ];
 
           shellHook = ''
-            export PGDATA="$PWD/.postgres"
+            # Anchor PGDATA to the repo root so subshells in subdirs
+            # (e.g. backend/) reuse the same cluster instead of seeding
+            # a stray .postgres there.
+            REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || pwd)"
+            export PGDATA="$REPO_ROOT/.postgres"
             export PGHOST="$PGDATA"
             export PGUSER="postgres"
             export PGDATABASE="postgres"