diff --git a/scripts/install.sh b/scripts/install.sh
index 3a503a3..b10087f 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -20,9 +20,11 @@
 #      built beforehand as a normal user:
 #        cargo build --release --locked --manifest-path rust/Cargo.toml
 #      (Rust >= 1.88 from rustup, plus pkg-config and libssl-dev)
-#   4. the Python training environment (.venv, `uv sync --frozen`): in place
-#      as the user running sudo (who pulled and built), otherwise as root;
-#      SKIP_UV=1 skips it
+#   4. the Python training environment (.venv, `uv sync --frozen`), as the
+#      owner of .venv (in place; else the user running sudo) or as root for a
+#      copy. uv is looked up on PATH and in that user's ~/.local/bin and
+#      ~/.cargo/bin (sudo and root shells often lack them); UV=/path/to/uv
+#      overrides, SKIP_UV=1 skips the step
 #   5. .env: created from .env.example on a fresh install (edit, then re-run);
 #      WEB_LISTEN and FORECAST_IN_COLLECTOR default to the production values
 #      when absent
@@ -104,16 +106,32 @@ log "Installing $BIN -> ${APP_DIR}/bin/ping-collector ($("$BIN" --version))"
 install -D -m 0755 -o root -g root "$BIN" "${APP_DIR}/bin/ping-collector"
 
 # 4. Python training environment ------------------------------------------------
+find_uv() { # user -> path of a uv binary that user can run
+    local home c
+    home="$(getent passwd "$1" | cut -d: -f6)"
+    for c in "${UV:-}" "$(command -v uv 2>/dev/null || true)" "${home}/.local/bin/uv" \
+        "${home}/.cargo/bin/uv" /root/.local/bin/uv /usr/local/bin/uv /usr/bin/uv; do
+        [ -n "$c" ] && [ -x "$c" ] && runuser -u "$1" -- test -x "$c" && {
+            echo "$c"
+            return 0
+        }
+    done
+    return 1
+}
+
 if [ "${SKIP_UV:-0}" != 1 ]; then
     uv_user=root # copy mode: handed to the service user below
-    [ "$in_place" = 1 ] && uv_user="${SUDO_USER:-root}"
-    log "Syncing the Python training environment (${APP_DIR}/.venv) as $uv_user"
-    if [ "$uv_user" = root ]; then
-        (cd "$APP_DIR" && uv sync --python 3.11 --frozen) ||
-            warn "uv sync failed: the monthly retrain needs ${APP_DIR}/.venv (uv sync --python 3.11 --frozen)"
+    if [ "$in_place" = 1 ]; then
+        uv_user="${SUDO_USER:-root}"
+        [ -d "${APP_DIR}/.venv" ] && uv_user="$(stat -c %U "${APP_DIR}/.venv")"
+    fi
+    if uv_bin="$(find_uv "$uv_user")"; then
+        log "Syncing the Python training environment (${APP_DIR}/.venv) as $uv_user with $uv_bin"
+        (cd "$APP_DIR" && runuser -u "$uv_user" -- env HOME="$(getent passwd "$uv_user" | cut -d: -f6)" \
+            "$uv_bin" sync --python 3.11 --frozen) ||
+            warn "uv sync failed: the monthly retrain needs ${APP_DIR}/.venv (uv sync --python 3.11 --frozen as $uv_user)"
     else
-        runuser -u "$uv_user" -- bash -lc "cd '$APP_DIR' && uv sync --python 3.11 --frozen" ||
-            warn "uv sync as $uv_user failed: run 'uv sync --python 3.11 --frozen' in $APP_DIR as the owner of .venv"
+        warn "uv not found for $uv_user (pass UV=/path/to/uv): ${APP_DIR}/.venv not synced"
     fi
 fi