From a69d57f49fead74c408860ca0f3c3bac2c5b79eb Mon Sep 17 00:00:00 2001
From: Asuka Minato <i@asukaminato.eu.org>
Date: Sun, 1 Nov 2026 12:49:04 +0900
Subject: [PATCH 1/2] test

---
 .../test/lsp/lsp_interaction/definition.rs    | 167 ++++++++++++++++++
 1 file changed, 167 insertions(+)

diff --git a/pyrefly/lib/test/lsp/lsp_interaction/definition.rs b/pyrefly/lib/test/lsp/lsp_interaction/definition.rs
index ef70043632..c6c00c9d64 100644
--- a/pyrefly/lib/test/lsp/lsp_interaction/definition.rs
+++ b/pyrefly/lib/test/lsp/lsp_interaction/definition.rs
@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+use std::fs;
 use std::path::PathBuf;
 use std::sync::Arc;
 
@@ -145,6 +146,172 @@ fn test_go_to_def_basic(root: &TempDir, workspace_folders: Option<Vec<(String, U
         .unwrap();
 }
 
+#[test]
+fn goto_definition_refreshes_closed_destination() {
+    let root = TempDir::with_prefix("pyrefly_goto_def_stale_disk").unwrap();
+    fs::write(
+        root.path().join("foo.py"),
+        "from bar import target\n\nvalue = target\n",
+    )
+    .unwrap();
+    fs::write(root.path().join("bar.py"), "target = 1\n").unwrap();
+
+    let mut interaction = LspInteraction::new();
+    interaction.set_root(root.path().to_path_buf());
+    interaction
+        .initialize(InitializeSettings {
+            ..Default::default()
+        })
+        .unwrap();
+    interaction.client.did_open("foo.py");
+
+    interaction
+        .client
+        .definition("foo.py", 2, 10)
+        .expect_definition_response_from_root("bar.py", 0, 0, 0, 6)
+        .unwrap();
+
+    fs::write(root.path().join("bar.py"), "# moved\ntarget = 1\n").unwrap();
+
+    // No watcher notification is sent. Repeated requests must use the new location.
+    for _ in 0..2 {
+        interaction
+            .client
+            .definition("foo.py", 2, 10)
+            .expect_definition_response_from_root("bar.py", 1, 0, 1, 6)
+            .unwrap();
+    }
+
+    interaction.shutdown().unwrap();
+}
+
+#[test]
+fn goto_definition_preserves_unsaved_source() {
+    let root = TempDir::with_prefix("pyrefly_goto_def_unsaved").unwrap();
+    fs::write(
+        root.path().join("foo.py"),
+        "from bar import first, second\nfrom other import unrelated\nvalue = first\nvalue = second\n",
+    )
+    .unwrap();
+    fs::write(root.path().join("bar.py"), "first = 1\nsecond = 2\n").unwrap();
+    fs::write(root.path().join("other.py"), "unrelated: int = 1\n").unwrap();
+
+    let mut interaction = LspInteraction::new();
+    interaction.set_root(root.path().to_path_buf());
+    interaction.initialize(Default::default()).unwrap();
+    interaction.client.did_open("foo.py");
+    interaction
+        .client
+        .hover("foo.py", 1, 20)
+        .expect_hover_response_with_markup(|markup| markup.is_some_and(|text| text.contains("int")))
+        .unwrap();
+    fs::write(root.path().join("other.py"), "unrelated: str = 'changed'\n").unwrap();
+    interaction.client.did_change(
+        "foo.py",
+        "from bar import first, second\nfrom other import unrelated\n# unsaved\nvalue = first\nvalue = missing\n",
+    );
+
+    // This position refers to `second` on disk, but to `first` in the buffer.
+    for _ in 0..2 {
+        interaction
+            .client
+            .definition("foo.py", 3, 10)
+            .expect_definition_response_from_root("bar.py", 0, 0, 0, 5)
+            .unwrap();
+    }
+    interaction
+        .client
+        .definition("foo.py", 4, 10)
+        .expect_response(json!(null))
+        .unwrap();
+
+    // A failed lookup must not replace the buffer with the disk contents.
+    interaction
+        .client
+        .definition("foo.py", 3, 10)
+        .expect_definition_response_from_root("bar.py", 0, 0, 0, 5)
+        .unwrap();
+
+    // Unsaved source edits must not cause unrelated disk modules to reload.
+    interaction
+        .client
+        .hover("foo.py", 1, 20)
+        .expect_hover_response_with_markup(|markup| markup.is_some_and(|text| text.contains("int")))
+        .unwrap();
+
+    // Refreshing the destination must still resolve the symbol from the buffer.
+    fs::write(
+        root.path().join("bar.py"),
+        "# moved\nfirst = 1\nsecond = 2\n",
+    )
+    .unwrap();
+    interaction
+        .client
+        .definition("foo.py", 3, 10)
+        .expect_definition_response_from_root("bar.py", 1, 0, 1, 5)
+        .unwrap();
+    interaction
+        .client
+        .definition("foo.py", 4, 10)
+        .expect_response(json!(null))
+        .unwrap();
+
+    interaction.shutdown().unwrap();
+}
+
+#[test]
+fn goto_definition_does_not_use_disk_for_unknown_buffer_symbol() {
+    let root = TempDir::with_prefix("pyrefly_goto_def_missing").unwrap();
+    fs::write(
+        root.path().join("foo.py"),
+        "from bar import target\nvalue = target\n",
+    )
+    .unwrap();
+    fs::write(root.path().join("bar.py"), "target = 1\n").unwrap();
+
+    let mut interaction = LspInteraction::new();
+    interaction.set_root(root.path().to_path_buf());
+    interaction.initialize(Default::default()).unwrap();
+    interaction.client.did_open("foo.py");
+    interaction
+        .client
+        .did_change("foo.py", "from bar import target\nvalue = missing\n");
+    interaction
+        .client
+        .definition("foo.py", 1, 10)
+        .expect_response(json!(null))
+        .unwrap();
+
+    interaction.shutdown().unwrap();
+}
+
+#[test]
+fn goto_definition_preserves_unsaved_destination() {
+    let root = TempDir::with_prefix("pyrefly_goto_def_open_destination").unwrap();
+    fs::write(
+        root.path().join("foo.py"),
+        "from bar import target\nvalue = target\n",
+    )
+    .unwrap();
+    fs::write(root.path().join("bar.py"), "target = 1\n").unwrap();
+
+    let mut interaction = LspInteraction::new();
+    interaction.set_root(root.path().to_path_buf());
+    interaction.initialize(Default::default()).unwrap();
+    interaction.client.did_open("foo.py");
+    interaction.client.did_open("bar.py");
+    interaction
+        .client
+        .did_change("bar.py", "# unsaved\ntarget = 1\n");
+    interaction
+        .client
+        .definition("bar.py", 1, 2)
+        .expect_definition_response_from_root("bar.py", 1, 0, 1, 6)
+        .unwrap();
+
+    interaction.shutdown().unwrap();
+}
+
 #[test]
 fn test_go_to_def_single_root() {
     let root = get_test_files_root();

From bc0e5d6366e48c783944adeb0fa22a97c0701c63 Mon Sep 17 00:00:00 2001
From: Asuka Minato <i@asukaminato.eu.org>
Date: Mon, 6 Apr 2026 17:57:13 +0900
Subject: [PATCH 2/2] fix

---
 pyrefly/lib/lsp/non_wasm/server.rs | 31 +++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/pyrefly/lib/lsp/non_wasm/server.rs b/pyrefly/lib/lsp/non_wasm/server.rs
index 3ca2aae429..32fa1f9f97 100644
--- a/pyrefly/lib/lsp/non_wasm/server.rs
+++ b/pyrefly/lib/lsp/non_wasm/server.rs
@@ -235,9 +235,11 @@ use pyrefly_python::module::TextRangeWithModule;
 use pyrefly_python::module_name::ModuleName;
 use pyrefly_python::module_name::ModuleNameWithKind;
 use pyrefly_python::module_path::ModulePath;
+use pyrefly_python::module_path::ModulePathDetails;
 use pyrefly_util::absolutize::Absolutize as _;
 use pyrefly_util::arc_id::ArcId;
 use pyrefly_util::events::CategorizedEvents;
+use pyrefly_util::fs_anyhow;
 use pyrefly_util::globs::FilteredGlobs;
 use pyrefly_util::globs::HiddenDirFilter;
 use pyrefly_util::includes::Includes as _;
@@ -2463,7 +2465,7 @@ impl Server {
                             params, &x.id,
                         )
                     {
-                        let response = match self.goto_definition(&transaction, params) {
+                        let response = match self.goto_definition(&mut transaction, params) {
                             Ok(response) => response,
                             Err(reason) => {
                                 telemetry_event.set_empty_response_reason(reason);
@@ -5034,7 +5036,7 @@ impl Server {
 
     fn goto_definition(
         &self,
-        transaction: &Transaction<'_>,
+        transaction: &mut Transaction<'_>,
         params: DefinitionParams,
     ) -> Result<Option<DefinitionResponse>, EmptyResponseReason> {
         let uri = &params.text_document_position_params.text_document.uri;
@@ -5044,7 +5046,30 @@ impl Server {
             .ok_or(EmptyResponseReason::ModuleInfoNotFound)?;
         let range =
             self.from_lsp_position(uri, &info, params.text_document_position_params.position);
-        let targets = transaction.goto_definition(&handle, range)?;
+        let mut targets = transaction.goto_definition(&handle, range)?;
+
+        // Client positions refer to open buffers. Only closed destinations can be
+        // refreshed from disk without changing the meaning of those positions.
+        let mut changed = SmallSet::new();
+        for target in &targets {
+            if let ModulePathDetails::FileSystem(path) = target.module.path().details()
+                && !self.open_files.read().contains_key(path.as_path())
+                && !target.module.is_notebook()
+                && let Ok(contents) = fs_anyhow::read_to_string(path)
+                && contents.as_str() != target.module.contents().as_str()
+            {
+                changed.insert(path.to_path_buf());
+            }
+        }
+        if !changed.is_empty() {
+            transaction.invalidate_disk(&changed.into_iter().collect::<Vec<_>>());
+            transaction.run(
+                std::slice::from_ref(&handle),
+                Require::Everything,
+                Some(&self.lsp_thread_pool),
+            );
+            targets = transaction.goto_definition(&handle, range)?;
+        }
         let mut lsp_targets = targets
             .iter()
             .filter_map(|x| self.to_lsp_location(x))