diff --git a/src/model.rs b/src/model.rs
index cde2811..96aea11 100644
--- a/src/model.rs
+++ b/src/model.rs
@@ -82,10 +82,10 @@ pub enum Mode { Lexical, Hybrid }
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Default)]
 pub enum IndexStatus {
-    Ok,               // packed file present and structurally valid
+    Ok,               // packed file present and matches the corpus + model
     #[default]
     Absent,           // no usable index — intentional lexical-only
-    Mismatch(String), // packed file present but structurally invalid; reason carried
+    Mismatch(String), // packed file present but structurally or semantically invalid; reason carried
 }
 
 impl std::fmt::Display for IndexStatus {
diff --git a/tests/pack_cli_tests.rs b/tests/pack_cli_tests.rs
index fe2b84f..88ab410 100644
--- a/tests/pack_cli_tests.rs
+++ b/tests/pack_cli_tests.rs
@@ -120,3 +120,37 @@ fn cli_packed_file_loads_back_as_ok_index() {
     assert!(vector.is_some(), "packed file written by the CLI must yield an index");
     assert_eq!(status, IndexStatus::Ok);
 }
+
+/// Positional alignment (spec § Testing strategy): the packed matrix stores one
+/// row per corpus entry in corpus-load order, so row `i` is the embedding of
+/// `entries[i].text`. The two entries carry order-revealing orthogonal vectors;
+/// if packing did not preserve corpus order the rows would come back swapped.
+#[test]
+fn cli_packed_rows_are_in_corpus_order() {
+    use alpha_id::packed::read_packed;
+    let dir = tempfile::tempdir().unwrap();
+    let corpus = dir.path().join("corpus.txt");
+    // alpha is line 1 (corpus entry 0), beta is line 2 (corpus entry 1).
+    std::fs::write(&corpus, format!("{}\n{}\n", corpus_line("alpha"), corpus_line("beta"))).unwrap();
+    let index_dir = dir.path().join("index");
+    std::fs::create_dir_all(&index_dir).unwrap();
+
+    let store = alpha_id::embed::EmbeddingStore::open(index_dir.to_str().unwrap(), "test/model").unwrap();
+    store.put("alpha", &[1.0f32, 0.0]).unwrap();
+    store.put("beta", &[0.0f32, 1.0]).unwrap();
+
+    let config = write_config(dir.path(), &corpus, &index_dir);
+    let out = Command::new(env!("CARGO_BIN_EXE_alpha-id"))
+        .args(["--config", config.to_str().unwrap(), "index", "--pack"])
+        .output()
+        .unwrap();
+    assert!(out.status.success(), "stderr: {}", String::from_utf8_lossy(&out.stderr));
+
+    let (_header, rows) = read_packed(&index_dir.join("packed.test_model.bin")).unwrap();
+    // Row i is the embedding of corpus entry i: alpha→[1,0] at row 0, beta→[0,1] at row 1.
+    assert_eq!(
+        rows,
+        vec![vec![1.0f32, 0.0], vec![0.0f32, 1.0]],
+        "packed rows must follow corpus-load order"
+    );
+}