Handle pre-epoch file timestamps consistently and record Rust audit

crates/searchi-core/tests/raw_source_hash.rs

@@ -90,3 +90,40 @@ fn oversized_text_and_unsupported_files_remain_filename_only() -> Result<()> {
     assert_eq!(index.search("large.txt", 10)?.len(), 1);
     Ok(())
 }
+
+#[test]
+fn pre_epoch_source_remains_searchable_and_verifiable() -> Result<()> {
+    let directory = tempfile::tempdir()?;
+    let path = directory.path().join("archived-notes.txt");
+    let content = "Historical supplier cancellation notice\n";
+    fs::write(&path, content)?;
+    fs::File::options().write(true).open(&path)?.set_times(
+        FileTimes::new().set_modified(std::time::UNIX_EPOCH - std::time::Duration::from_secs(1)),
+    )?;
+    let mut index = SearchIndex::open(":memory:")?;
+    let report = index.index_folder(directory.path())?;
+    assert_eq!(report.indexed, 1);
+    assert_eq!(report.failures, 0);
+    assert_eq!(index.search("archived-notes.txt", 10)?.len(), 1);
+    assert_eq!(index.search("cancellation", 10)?.len(), 1);
+    let passage = index.passage_batch(0, 1)?.remove(0);
+    assert_eq!(
+        index.file_signature(&passage.path)?,
+        Some((content.len() as u64, -1_000_000_000))
+    );
+    assert_eq!(
+        index.extracted_source_hash(&passage.path)?,
+        Some(format!("{:x}", Sha256::digest(content.as_bytes())))
+    );
+    assert_eq!(
+        index
+            .source_passage(&passage.path, &passage.source, 8192)?
+            .unwrap()
+            .text,
+        content
+    );
+    let rescan = index.index_folder(directory.path())?;
+    assert_eq!(rescan.unchanged, 1);
+    assert_eq!(rescan.indexed, 0);
+    Ok(())
+}