@@ -666,7 +666,8 @@ pub(crate) async fn nested_project_skips(
     let shell_dir = std::env::current_dir()
         .ok()
         .map(|d| std::fs::canonicalize(&d).unwrap_or(d));
-    let mut by_project: BTreeMap<String, Vec<String>> = BTreeMap::new();
+    // Project -> (whether it has a lockfile of its own, its purls).
+    let mut by_project: BTreeMap<String, (bool, Vec<String>)> = BTreeMap::new();
     let mut skipped = HashSet::new();
     for (purl, project) in candidates {
         let project = std::fs::canonicalize(&project).unwrap_or(project);
@@ -678,7 +679,12 @@ pub(crate) async fn nested_project_skips(
             .to_string_lossy()
             .replace('\\', "/");
         skipped.insert(PurlKey::new(&purl));
-        by_project.entry(shown).or_default().push(purl);
+        let locked = socket_patch_core::hosted::governing_root::has_own_npm_family_lock(&project);
+        by_project
+            .entry(shown)
+            .or_insert_with(|| (locked, Vec::new()))
+            .1
+            .push(purl);
     }
     // Spelled out per mode so the remedy-command check can parse each.
     let rerun = |dir: &str| {
@@ -690,22 +696,35 @@ pub(crate) async fn nested_project_skips(
     };
     let warnings = by_project
         .into_iter()
-        .map(|(dir, purls)| {
+        .map(|(dir, (locked, purls))| {
             let (verb, left) = if purls.len() == 1 {
                 ("is", "it is")
             } else {
                 ("are", "they are")
             };
-            (
-                NESTED_PROJECT_SKIPPED.to_string(),
+            let word = shell_word(&dir);
+            // #1554: a project installed without a lockfile has none for a
+            // hosted or vendored run of its own to rewire either.
+            let detail = if locked {
                 format!(
                     "{} {verb} installed only by {dir}, a separate npm project with its own \
                      lockfile; this run rewires only this directory's lockfile, so {left} left \
                      alone; run {} to patch that project",
                     purls.join(", "),
-                    rerun(&shell_word(&dir)),
-                ),
-            )
+                    rerun(&word),
+                )
+            } else {
+                format!(
+                    "{} {verb} installed only by {dir}, a separate npm project installed \
+                     without a lockfile; this run rewires only this directory's lockfile, so \
+                     {left} left alone; to patch that project, create its lockfile \
+                     (`npm install --package-lock` in {dir}) and run {}, or patch its \
+                     node_modules in place with `socket-patch scan --mode agent {word}`",
+                    purls.join(", "),
+                    rerun(&word),
+                )
+            };
+            (NESTED_PROJECT_SKIPPED.to_string(), detail)
         })
         .collect();
     (skipped, warnings)
 
@@ -425,3 +425,65 @@ async fn warning_names_the_path_from_the_shells_directory() {
         "{detail}"
     );
 }
+
+/// #1554: [`write_repo`], but `tools/x` was installed without a lock
+/// (`package-lock=false` in its `.npmrc`, or `npm install
+/// --no-package-lock`).
+fn write_lockless_repo(root: &Path, npmrc: bool) {
+    write_repo(root);
+    std::fs::remove_file(root.join("tools/x/package-lock.json")).unwrap();
+    if npmrc {
+        std::fs::write(root.join("tools/x/.npmrc"), "package-lock=false\n").unwrap();
+    }
+}
+
+/// #1554: a lockless nested project is as independent as a locked one.
+/// Every run ended `partialFailure`, exit 1, with
+/// `vendor_lock_entry_not_found`, and the in-run VEX was dropped.
+#[tokio::test]
+async fn root_vendored_scan_skips_a_lockless_nested_project() {
+    for npmrc in [true, false] {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        write_lockless_repo(root, npmrc);
+        let mock = MockServer::start().await;
+        mount_api(&mock).await;
+
+        for run in 1..=2 {
+            let (code, stdout, stderr) = run_scan(root, &mock.uri(), "vendored", &[]);
+            let v = parse_json_envelope(&stdout);
+            assert_eq!(
+                code, 0,
+                "npmrc={npmrc} run {run}: exit 0\nstdout={stdout}\nstderr={stderr}"
+            );
+            assert_eq!(v["status"], "success", "npmrc={npmrc} run {run}: {v:#}");
+            assert_nested_skipped(&v);
+            let detail = warning(&v, WARNING).unwrap()["detail"].as_str().unwrap();
+            assert!(detail.contains("without a lockfile"), "{detail}");
+            assert!(
+                detail.contains("npm install --package-lock")
+                    && detail.contains("scan --mode agent tools/x"),
+                "names a remedy that works without a lockfile: {detail}"
+            );
+        }
+        let root_lock = std::fs::read_to_string(root.join("package-lock.json")).unwrap();
+        assert!(root_lock.contains(".socket/vendor"), "{root_lock}");
+        assert!(!root.join("tools/x/package-lock.json").exists());
+
+        let out = root.join("out.vex.json");
+        let (code, stdout, stderr) = run_scan(
+            root,
+            &mock.uri(),
+            "vendored",
+            &[
+                "--vex",
+                out.to_str().unwrap(),
+                "--vex-product",
+                "pkg:npm/root@1.0.0",
+            ],
+        );
+        assert_eq!(code, 0, "npmrc={npmrc}: stdout={stdout}\nstderr={stderr}");
+        let doc = std::fs::read_to_string(&out).expect("the in-run VEX is written");
+        assert!(!doc.contains("left-pad"), "{doc}");
+    }
+}