feat: add local agent MCP tools and optional source-grounded AI answers

crates/searchi-core/tests/source_access.rs

@@ -0,0 +1,76 @@
+use searchi_core::{SearchIndex, SourceLocation};
+use std::fs;
+
+#[test]
+fn document_source_is_bounded_current_and_index_scoped() {
+    let directory = tempfile::tempdir().unwrap();
+    let files = directory.path().join("files");
+    fs::create_dir(&files).unwrap();
+    let file = files.join("notes.txt");
+    fs::write(&file, "héllo supplier notice").unwrap();
+    let mut index = SearchIndex::open(directory.path().join("index.sqlite")).unwrap();
+    index.index_folder(&files).unwrap();
+    let path = fs::canonicalize(&file)
+        .unwrap()
+        .to_string_lossy()
+        .into_owned();
+    let original_version = index.file_signature(&path).unwrap().unwrap();
+    let source = SourceLocation {
+        kind: "line".into(),
+        number: 1,
+    };
+    let passage = index.source_passage(&path, &source, 5).unwrap().unwrap();
+    assert_eq!(passage.text, "héllo");
+    assert!(index.source_passage(&path, &source, 8193).is_err());
+    assert!(index
+        .source_passage(
+            &path,
+            &SourceLocation {
+                kind: "timestamp_ms".into(),
+                number: 0
+            },
+            100
+        )
+        .is_err());
+    assert!(index
+        .source_passage(
+            &path,
+            &SourceLocation {
+                kind: "line".into(),
+                number: 99
+            },
+            100
+        )
+        .unwrap()
+        .is_none());
+    let other = files.join("unindexed.txt");
+    fs::write(&other, "private unrelated content").unwrap();
+    assert!(index
+        .file_signature(&other.to_string_lossy())
+        .unwrap()
+        .is_none());
+    assert!(index
+        .source_passage(&other.to_string_lossy(), &source, 100)
+        .unwrap()
+        .is_none());
+    fs::write(&file, "changed content with different size").unwrap();
+    assert!(index.source_passage(&path, &source, 100).unwrap().is_none());
+    index.index_folder(&files).unwrap();
+    assert_ne!(
+        index.file_signature(&path).unwrap().unwrap(),
+        original_version
+    );
+    assert!(index.source_passage(&path, &source, 100).unwrap().is_some());
+    let old_time = fs::metadata(&file).unwrap().modified().unwrap();
+    let same_size = "x".repeat(fs::metadata(&file).unwrap().len() as usize);
+    fs::write(&file, same_size).unwrap();
+    fs::File::options()
+        .write(true)
+        .open(&file)
+        .unwrap()
+        .set_modified(old_time + std::time::Duration::from_secs(2))
+        .unwrap();
+    assert!(index.source_passage(&path, &source, 100).unwrap().is_none());
+    fs::remove_file(&file).unwrap();
+    assert!(index.source_passage(&path, &source, 100).unwrap().is_none());
+}