@@ -2537,15 +2537,25 @@ impl StagedSource {
 /// neither the pristine release nor this patch's output. The re-vendor
 /// then takes the pristine artifact from the lock / registry / service, as
 /// a lock-only checkout does, instead of reporting it not installed.
+///
+/// A PyPI install under a live hosted pin (`hosted_pinned`) is the same
+/// story after a hosted scan (#1105): `uv sync` / `poetry install` from
+/// the hosted lock installs a hosted patch's bytes, whichever generation
+/// the pin names now. The pin names no release variant, so it only answers
+/// for a sole candidate; gems keep their installed dir, which the gem
+/// backend reads to refuse a platform gem.
 fn superseded_install(
     ledger: &VendorState,
     candidate: &str,
     record: &PatchRecord,
     sole_candidate: bool,
+    hosted_pinned: bool,
 ) -> bool {
     lookup_entry_kv(&ledger.entries, candidate).is_some_and(|(key, entry)| {
         entry.uuid != record.uuid && (sole_candidate || key == candidate)
-    })
+    }) || (sole_candidate
+        && hosted_pinned
+        && matches!(Ecosystem::from_purl(candidate), Some(Ecosystem::Pypi)))
 }
 
 #[allow(clippy::too_many_arguments)]
@@ -2605,8 +2615,13 @@ async fn plan_service_downloads(
                         if !variant_matches_installed(Some(
                             &verify_file_patch(dir, file, info).await.status,
                         )) {
-                            if !superseded_install(ledger, candidate, record, candidates.len() == 1)
-                            {
+                            if !superseded_install(
+                                ledger,
+                                candidate,
+                                record,
+                                candidates.len() == 1,
+                                takeover_blocked(candidate),
+                            ) {
                                 continue;
                             }
                             source_path = &uninstalled;
@@ -3093,8 +3108,13 @@ pub(crate) async fn vendor_records_reusing(
                                 .await
                                 .status,
                         )) {
-                            if !superseded_install(&state, candidate, record, candidates.len() == 1)
-                            {
+                            if !superseded_install(
+                                &state,
+                                candidate,
+                                record,
+                                candidates.len() == 1,
+                                hosted_pin_of(candidate).is_some(),
+                            ) {
                                 continue;
                             }
                             candidate_source = PackageSource::Installed(&uninstalled);
@@ -4909,6 +4929,28 @@ mod plan_gate_tests {
         }
     }
 
+    /// #1105: a live hosted pin marks a PyPI install superseded (a hosted
+    /// sync installed a hosted patch's bytes), so the takeover vendors the
+    /// record instead of reporting it not installed. The pin names no
+    /// variant, so only a sole candidate counts, and gems keep their
+    /// installed dir for the platform-gem refusal.
+    #[test]
+    fn hosted_pin_marks_a_pypi_install_superseded() {
+        let ledger = VendorState::default();
+        let pypi = "pkg:pypi/six@1.16.0";
+        let b = record(UUID_B);
+        assert!(superseded_install(&ledger, pypi, &b, true, true));
+        assert!(!superseded_install(&ledger, pypi, &b, false, true));
+        assert!(!superseded_install(&ledger, pypi, &b, true, false));
+        assert!(!superseded_install(
+            &ledger,
+            "pkg:gem/nokogiri@1.16.0",
+            &b,
+            true,
+            true
+        ));
+    }
+
     /// The download plan runs every record through its backend's own gate:
     /// a package the backend refuses before its first service call is
     /// never planned, wherever it sits in the loop order. Here the refused
 
@@ -995,6 +995,67 @@ async fn poetry_revendors_to_a_superseding_patch_over_a_patched_venv() {
     );
 }
 
+/// #1105: a project hosted at patch A whose venv was then synced from the
+/// hosted lock (`uv sync`, `poetry install`, `uv pip install -r`), so six
+/// holds A's patched bytes, moves to vendored at the superseding patch B.
+/// The installed copy matches neither the pristine release nor B's
+/// output; it used to be dropped as `package_not_installed` (exit 1, the
+/// project left hosted on A) while `scan --mode vendored --dry-run`
+/// previewed success. The takeover must restore the upstream entry and
+/// vendor B.
+#[tokio::test]
+async fn hosted_to_vendored_takes_a_superseding_patch_over_a_hosted_venv() {
+    let lanes: [(&str, StageFn); 3] = [
+        ("uv", stage_uv_with_sibling),
+        ("poetry", stage_poetry),
+        ("requirements", stage_requirements),
+    ];
+    for (lane, stage) in lanes {
+        let (_tmp, root) = project();
+        let files = stage(&root);
+        let server = MockServer::start().await;
+        let hosted_url = mount_hosted_api(&server, true).await;
+        let (code, env) = hosted_scan(&root, &server);
+        assert_eq!(code, 0, "{lane}: hosted scan at A: {env:#}");
+        assert!(
+            files.iter().any(|f| std::fs::read_to_string(root.join(f))
+                .unwrap()
+                .contains(&hosted_url)),
+            "{lane}: hosted mode pins A: {env:#}"
+        );
+
+        let venv = root.join("../hosted-venv");
+        venv_installed_from_patch_a(&venv);
+        stage_manifest_with(&root, UUID_B, PATCHED_B);
+        prebuilt_common::mount_project(&server, &root).await;
+        mount_pypi_json(&server).await;
+        let uri = server.uri();
+        let pypi = format!("{uri}/pypi");
+        let extra = [
+            ("VIRTUAL_ENV", venv.to_str().unwrap()),
+            ("SOCKET_PYPI_JSON_API", pypi.as_str()),
+        ];
+        let args = ["vendor", "--patch-server-url", &uri, "--vendor-url", &uri];
+
+        let (code, env) = run_cli(&root, &args, &extra);
+        assert_eq!(code, 0, "{lane}: takeover onto B: {env:#}");
+        assert!(
+            !env.to_string().contains("package_not_installed"),
+            "{lane}: the installed copy is not reported missing: {env:#}"
+        );
+        let wired: String = files
+            .iter()
+            .map(|f| std::fs::read_to_string(root.join(f)).unwrap())
+            .collect();
+        assert!(
+            wired.contains(&format!(".socket/vendor/pypi/{UUID_B}/"))
+                && !wired.contains(&hosted_url)
+                && !wired.contains(UUID),
+            "{lane}: wired to vendored B, hosted A gone:\n{wired}"
+        );
+    }
+}
+
 const UV_LOCK: &str = r#"version = 1
 revision = 2
 requires-python = ">=3.9"