diff --git a/crates/keymap_editor/src/keymap_editor.rs b/crates/keymap_editor/src/keymap_editor.rs
index 76c14ccfe4..fce98ef596 100644
--- a/crates/keymap_editor/src/keymap_editor.rs
+++ b/crates/keymap_editor/src/keymap_editor.rs
@@ -23,7 +23,9 @@ use gpui::{
 use language::{Language, LanguageConfig, ToOffset as _};
 use notifications::status_toast::{StatusToast, ToastIcon};
 use project::{CompletionDisplayOptions, Project};
-use settings::{BaseKeymap, KeybindSource, KeymapFile, Settings as _, SettingsAssets};
+use settings::{
+    BaseKeymap, KeybindSource, KeymapFile, Settings as _, SettingsAssets, infer_json_indent_size,
+};
 use ui::{
     ActiveTheme as _, App, Banner, BorrowAppContext, ContextMenu, IconButtonShape, Indicator,
     Modal, ModalFooter, ModalHeader, ParentElement as _, PopoverMenu, Render, Section,
@@ -1198,13 +1200,12 @@ impl KeymapEditor {
         else {
             return;
         };
-        let tab_size = cx.global::<settings::SettingsStore>().json_tab_size();
         self.previous_edit = Some(PreviousEdit::ScrollBarOffset(
             self.table_interaction_state.read(cx).scroll_offset(),
         ));
         let keyboard_mapper = cx.keyboard_mapper().clone();
         cx.spawn(async move |_, _| {
-            remove_keybinding(to_remove, &fs, tab_size, keyboard_mapper.as_ref()).await
+            remove_keybinding(to_remove, &fs, keyboard_mapper.as_ref()).await
         })
         .detach_and_notify_err(window, cx);
     }
@@ -2288,7 +2289,6 @@ impl KeybindingEditorModal {
     fn save(&mut self, cx: &mut Context<Self>) -> Result<(), InputError> {
         let existing_keybind = self.editing_keybind.clone();
         let fs = self.fs.clone();
-        let tab_size = cx.global::<settings::SettingsStore>().json_tab_size();
 
         let mut new_keystrokes = self.validate_keystrokes(cx).map_err(InputError::error)?;
         new_keystrokes
@@ -2367,7 +2367,6 @@ impl KeybindingEditorModal {
                 &action_mapping,
                 new_action_args.as_deref(),
                 &fs,
-                tab_size,
                 keyboard_mapper.as_ref(),
             )
             .await
@@ -3019,13 +3018,14 @@ async fn save_keybinding_update(
     action_mapping: &ActionMapping,
     new_args: Option<&str>,
     fs: &Arc<dyn Fs>,
-    tab_size: usize,
     keyboard_mapper: &dyn PlatformKeyboardMapper,
 ) -> anyhow::Result<()> {
     let keymap_contents = settings::KeymapFile::load_keymap_file(fs)
         .await
         .context("Failed to load keymap file")?;
 
+    let tab_size = infer_json_indent_size(&keymap_contents);
+
     let existing_keystrokes = existing.keystrokes().unwrap_or_default();
     let existing_context = existing.context().and_then(KeybindContextString::local_str);
     let existing_args = existing
@@ -3089,7 +3089,6 @@ async fn save_keybinding_update(
 async fn remove_keybinding(
     existing: ProcessedBinding,
     fs: &Arc<dyn Fs>,
-    tab_size: usize,
     keyboard_mapper: &dyn PlatformKeyboardMapper,
 ) -> anyhow::Result<()> {
     let Some(keystrokes) = existing.keystrokes() else {
@@ -3098,6 +3097,7 @@ async fn remove_keybinding(
     let keymap_contents = settings::KeymapFile::load_keymap_file(fs)
         .await
         .context("Failed to load keymap file")?;
+    let tab_size = infer_json_indent_size(&keymap_contents);
 
     let operation = settings::KeybindUpdateOperation::Remove {
         target: settings::KeybindUpdateTarget {
diff --git a/crates/migrator/src/migrations.rs b/crates/migrator/src/migrations.rs
index 1b8ede68b1..0b35a238c6 100644
--- a/crates/migrator/src/migrations.rs
+++ b/crates/migrator/src/migrations.rs
@@ -103,7 +103,7 @@ pub(crate) mod m_2025_07_08 {
 pub(crate) mod m_2025_10_01 {
     mod settings;
 
-    pub(crate) use settings::SETTINGS_PATTERNS;
+    pub(crate) use settings::flatten_code_actions_formatters;
 }
 
 pub(crate) mod m_2025_10_02 {
diff --git a/crates/migrator/src/migrations/m_2025_10_01/settings.rs b/crates/migrator/src/migrations/m_2025_10_01/settings.rs
index 4f1e7a642f..84cf950491 100644
--- a/crates/migrator/src/migrations/m_2025_10_01/settings.rs
+++ b/crates/migrator/src/migrations/m_2025_10_01/settings.rs
@@ -1,109 +1,74 @@
-use std::ops::Range;
-use tree_sitter::{Query, QueryMatch};
+use crate::patterns::migrate_language_setting;
+use anyhow::Result;
+use serde_json::Value;
 
-use crate::MigrationPatterns;
-
-pub const SETTINGS_PATTERNS: MigrationPatterns =
-    &[(FORMATTER_PATTERN, migrate_code_action_formatters)];
-
-const FORMATTER_PATTERN: &str = r#"
-        (object
-            (pair
-                key: (string (string_content) @formatter) (#any-of? @formatter "formatter" "format_on_save")
-                value: [
-                    (array
-                        (object
-                            (pair
-                                key: (string (string_content) @code-actions-key) (#eq? @code-actions-key "code_actions")
-                                value: (object
-                                    ((pair) @code-action ","?)*
-                                )
-                            )
-                        ) @code-actions-obj
-                    ) @formatter-array
-                    (object
-                        (pair
-                            key: (string (string_content) @code-actions-key) (#eq? @code-actions-key "code_actions")
-                            value: (object
-                                ((pair) @code-action ","?)*
-                            )
-                        )
-                    ) @code-actions-obj
-                ]
-            )
-        )
-"#;
-
-pub fn migrate_code_action_formatters(
-    contents: &str,
-    mat: &QueryMatch,
-    query: &Query,
-) -> Option<(Range<usize>, String)> {
-    let code_actions_obj_ix = query.capture_index_for_name("code-actions-obj")?;
-    let code_actions_obj_node = mat.nodes_for_capture_index(code_actions_obj_ix).next()?;
-
-    let mut code_actions = vec![];
-
-    let code_actions_ix = query.capture_index_for_name("code-action")?;
-    for code_action_node in mat.nodes_for_capture_index(code_actions_ix) {
-        let Some(enabled) = code_action_node
-            .child_by_field_name("value")
-            .map(|n| n.kind() != "false")
-        else {
-            continue;
+pub fn flatten_code_actions_formatters(value: &mut Value) -> Result<()> {
+    migrate_language_setting(value, |value, _path| {
+        let Some(obj) = value.as_object_mut() else {
+            return Ok(());
         };
-        if !enabled {
-            continue;
-        }
-        let Some(name) = code_action_node
-            .child_by_field_name("key")
-            .and_then(|n| n.child(1))
-            .map(|n| &contents[n.byte_range()])
-        else {
-            continue;
-        };
-        code_actions.push(name);
-    }
+        for key in ["formatter", "format_on_save"] {
+            let Some(formatter) = obj.get_mut(key) else {
+                continue;
+            };
+            let new_formatter = match formatter {
+                Value::Array(arr) => {
+                    let mut new_arr = Vec::new();
+                    let mut found_code_actions = false;
+                    for item in arr {
+                        let Some(obj) = item.as_object() else {
+                            new_arr.push(item.clone());
+                            continue;
+                        };
+                        let code_actions_obj = obj
+                            .get("code_actions")
+                            .and_then(|code_actions| code_actions.as_object());
+                        let Some(code_actions) = code_actions_obj else {
+                            new_arr.push(item.clone());
+                            continue;
+                        };
+                        found_code_actions = true;
+                        for (name, enabled) in code_actions {
+                            if !enabled.as_bool().unwrap_or(true) {
+                                continue;
+                            }
+                            new_arr.push(serde_json::json!({
+                                "code_action": name
+                            }));
+                        }
+                    }
+                    if !found_code_actions {
+                        continue;
+                    }
+                    Value::Array(new_arr)
+                }
+                Value::Object(obj) => {
+                    let mut new_arr = Vec::new();
+                    let code_actions_obj = obj
+                        .get("code_actions")
+                        .and_then(|code_actions| code_actions.as_object());
+                    let Some(code_actions) = code_actions_obj else {
+                        continue;
+                    };
+                    for (name, enabled) in code_actions {
+                        if !enabled.as_bool().unwrap_or(true) {
+                            continue;
+                        }
+                        new_arr.push(serde_json::json!({
+                            "code_action": name
+                        }));
+                    }
+                    if new_arr.len() == 1 {
+                        new_arr.pop().unwrap()
+                    } else {
+                        Value::Array(new_arr)
+                    }
+                }
+                _ => continue,
+            };
 
-    let indent = query
-        .capture_index_for_name("formatter")
-        .and_then(|ix| mat.nodes_for_capture_index(ix).next())
-        .map(|node| node.start_position().column + 1)
-        .unwrap_or(2);
-
-    let mut code_actions_str = code_actions
-        .into_iter()
-        .map(|code_action| format!(r#"{{ "code_action": "{}" }}"#, code_action))
-        .collect::<Vec<_>>()
-        .join(&format!(",\n{}", " ".repeat(indent)));
-    let is_array = query
-        .capture_index_for_name("formatter-array")
-        .map(|ix| mat.nodes_for_capture_index(ix).count() > 0)
-        .unwrap_or(false);
-    if !is_array {
-        code_actions_str.insert_str(0, &" ".repeat(indent));
-        code_actions_str.insert_str(0, "[\n");
-        code_actions_str.push('\n');
-        code_actions_str.push_str(&" ".repeat(indent.saturating_sub(2)));
-        code_actions_str.push_str("]");
-    }
-    let mut replace_range = code_actions_obj_node.byte_range();
-    if is_array && code_actions_str.is_empty() {
-        let mut cursor = code_actions_obj_node.parent().unwrap().walk();
-        cursor.goto_first_child();
-        while cursor.node().id() != code_actions_obj_node.id() && cursor.goto_next_sibling() {}
-        while cursor.goto_next_sibling()
-            && (cursor.node().is_extra()
-                || cursor.node().is_missing()
-                || cursor.node().kind() == "comment")
-        {}
-        if cursor.node().kind() == "," {
-            // found comma, delete up to next node
-            while cursor.goto_next_sibling()
-                && (cursor.node().is_extra() || cursor.node().is_missing())
-            {}
-            replace_range.end = cursor.node().range().start_byte;
+            obj.insert(key.to_string(), new_formatter);
         }
-    }
-    Some((replace_range, code_actions_str))
+        return Ok(());
+    })
 }
diff --git a/crates/migrator/src/migrations/m_2025_10_02/settings.rs b/crates/migrator/src/migrations/m_2025_10_02/settings.rs
index 2434ae4d0e..cb0d63ca85 100644
--- a/crates/migrator/src/migrations/m_2025_10_02/settings.rs
+++ b/crates/migrator/src/migrations/m_2025_10_02/settings.rs
@@ -1,19 +1,10 @@
 use anyhow::Result;
 use serde_json::Value;
 
+use crate::patterns::migrate_language_setting;
+
 pub fn remove_formatters_on_save(value: &mut Value) -> Result<()> {
-    remove_formatters_on_save_inner(value, &[])?;
-    let languages = value
-        .as_object_mut()
-        .and_then(|obj| obj.get_mut("languages"))
-        .and_then(|languages| languages.as_object_mut());
-    if let Some(languages) = languages {
-        for (language_name, language) in languages.iter_mut() {
-            let path = vec!["languages", language_name];
-            remove_formatters_on_save_inner(language, &path)?;
-        }
-    }
-    Ok(())
+    migrate_language_setting(value, remove_formatters_on_save_inner)
 }
 
 fn remove_formatters_on_save_inner(value: &mut Value, path: &[&str]) -> Result<()> {
diff --git a/crates/migrator/src/migrations/m_2025_10_10/settings.rs b/crates/migrator/src/migrations/m_2025_10_10/settings.rs
index 1d07be71a1..694f887b59 100644
--- a/crates/migrator/src/migrations/m_2025_10_10/settings.rs
+++ b/crates/migrator/src/migrations/m_2025_10_10/settings.rs
@@ -1,19 +1,10 @@
 use anyhow::Result;
 use serde_json::Value;
 
+use crate::patterns::migrate_language_setting;
+
 pub fn remove_code_actions_on_format(value: &mut Value) -> Result<()> {
-    remove_code_actions_on_format_inner(value, &[])?;
-    let languages = value
-        .as_object_mut()
-        .and_then(|obj| obj.get_mut("languages"))
-        .and_then(|languages| languages.as_object_mut());
-    if let Some(languages) = languages {
-        for (language_name, language) in languages.iter_mut() {
-            let path = vec!["languages", language_name];
-            remove_code_actions_on_format_inner(language, &path)?;
-        }
-    }
-    Ok(())
+    migrate_language_setting(value, remove_code_actions_on_format_inner)
 }
 
 fn remove_code_actions_on_format_inner(value: &mut Value, path: &[&str]) -> Result<()> {
diff --git a/crates/migrator/src/migrator.rs b/crates/migrator/src/migrator.rs
index aea11f98c4..7b4182b005 100644
--- a/crates/migrator/src/migrator.rs
+++ b/crates/migrator/src/migrator.rs
@@ -74,6 +74,7 @@ fn run_migrations(text: &str, migrations: &[MigrationType]) -> Result<Option<Str
 
     let mut current_text = text.to_string();
     let mut result: Option<String> = None;
+    let json_indent_size = settings::infer_json_indent_size(&current_text);
     for migration in migrations.iter() {
         let migrated_text = match migration {
             MigrationType::TreeSitter(patterns, query) => migrate(&current_text, patterns, query)?,
@@ -92,7 +93,7 @@ fn run_migrations(text: &str, migrations: &[MigrationType]) -> Result<Option<Str
                     settings::update_value_in_json_text(
                         &mut current,
                         &mut vec![],
-                        2,
+                        json_indent_size,
                         &old_value,
                         &new_value,
                         &mut edits,
@@ -204,10 +205,7 @@ pub fn migrate_settings(text: &str) -> Result<Option<String>> {
             migrations::m_2025_07_08::SETTINGS_PATTERNS,
             &SETTINGS_QUERY_2025_07_08,
         ),
-        MigrationType::TreeSitter(
-            migrations::m_2025_10_01::SETTINGS_PATTERNS,
-            &SETTINGS_QUERY_2025_10_01,
-        ),
+        MigrationType::Json(migrations::m_2025_10_01::flatten_code_actions_formatters),
         MigrationType::Json(migrations::m_2025_10_02::remove_formatters_on_save),
         MigrationType::TreeSitter(
             migrations::m_2025_10_03::SETTINGS_PATTERNS,
@@ -328,10 +326,6 @@ define_query!(
     SETTINGS_QUERY_2025_07_08,
     migrations::m_2025_07_08::SETTINGS_PATTERNS
 );
-define_query!(
-    SETTINGS_QUERY_2025_10_01,
-    migrations::m_2025_10_01::SETTINGS_PATTERNS
-);
 define_query!(
     SETTINGS_QUERY_2025_10_03,
     migrations::m_2025_10_03::SETTINGS_PATTERNS
@@ -351,10 +345,11 @@ mod tests {
     use super::*;
     use unindent::Unindent as _;
 
+    #[track_caller]
     fn assert_migrated_correctly(migrated: Option<String>, expected: Option<&str>) {
         match (&migrated, &expected) {
             (Some(migrated), Some(expected)) => {
-                pretty_assertions::assert_str_eq!(migrated, expected);
+                pretty_assertions::assert_str_eq!(expected, migrated);
             }
             _ => {
                 pretty_assertions::assert_eq!(migrated.as_deref(), expected);
@@ -372,6 +367,7 @@ mod tests {
         assert_migrated_correctly(migrated, output);
     }
 
+    #[track_caller]
     fn assert_migrate_settings_with_migrations(
         migrations: &[MigrationType],
         input: &str,
@@ -1343,24 +1339,28 @@ mod tests {
     fn test_flatten_code_action_formatters_basic_array() {
         assert_migrate_settings(
             &r#"{
-                "formatter": [
-                  {
-                      "code_actions": {
-                          "included-1": true,
-                          "included-2": true,
-                          "excluded": false,
-                      }
-                  }
-                ]
-            }"#
+        "formatter": [
+          {
+            "code_actions": {
+              "included-1": true,
+              "included-2": true,
+              "excluded": false,
+            }
+          }
+        ]
+      }"#
             .unindent(),
             Some(
                 &r#"{
-                "formatter": [
-                  { "code_action": "included-1" },
-                  { "code_action": "included-2" }
-                ]
-            }"#
+        "formatter": [
+          {
+            "code_action": "included-1"
+          },
+          {
+            "code_action": "included-2"
+          }
+        ]
+      }"#
                 .unindent(),
             ),
         );
@@ -1370,21 +1370,25 @@ mod tests {
     fn test_flatten_code_action_formatters_basic_object() {
         assert_migrate_settings(
             &r#"{
-                "formatter": {
-                    "code_actions": {
-                        "included-1": true,
-                        "excluded": false,
-                        "included-2": true
-                    }
-                }
-            }"#
+        "formatter": {
+          "code_actions": {
+            "included-1": true,
+            "excluded": false,
+            "included-2": true
+          }
+        }
+      }"#
             .unindent(),
             Some(
                 &r#"{
-                    "formatter": [
-                      { "code_action": "included-1" },
-                      { "code_action": "included-2" }
-                    ]
+                  "formatter": [
+                    {
+                      "code_action": "included-1"
+                    },
+                    {
+                      "code_action": "included-2"
+                    }
+                  ]
                 }"#
                 .unindent(),
             ),
@@ -1394,47 +1398,57 @@ mod tests {
     #[test]
     fn test_flatten_code_action_formatters_array_with_multiple_action_blocks() {
         assert_migrate_settings(
-            r#"{
-                "formatter": [
-                  {
-                      "code_actions": {
-                          "included-1": true,
-                          "included-2": true,
-                          "excluded": false,
-                      }
-                  },
-                  {
-                    "language_server": "ruff"
-                  },
-                  {
-                      "code_actions": {
-                          "excluded": false,
-                          "excluded-2": false,
-                      }
-                  }
-                  // some comment
-                  ,
-                  {
-                      "code_actions": {
-                        "excluded": false,
-                        "included-3": true,
-                        "included-4": true,
-                      }
-                  },
-                ]
-            }"#,
+            &r#"{
+          "formatter": [
+            {
+               "code_actions": {
+                  "included-1": true,
+                  "included-2": true,
+                  "excluded": false,
+               }
+            },
+            {
+              "language_server": "ruff"
+            },
+            {
+               "code_actions": {
+                  "excluded": false,
+                  "excluded-2": false,
+               }
+            }
+            // some comment
+            ,
+            {
+               "code_actions": {
+                "excluded": false,
+                "included-3": true,
+                "included-4": true,
+               }
+            },
+          ]
+        }"#
+            .unindent(),
             Some(
-                r#"{
-                "formatter": [
-                  { "code_action": "included-1" },
-                  { "code_action": "included-2" },
-                  {
-                    "language_server": "ruff"
-                  },
-                  { "code_action": "included-3" },
-                  { "code_action": "included-4" },
-                ]
-            }"#,
+                &r#"{
+        "formatter": [
+          {
+            "code_action": "included-1"
+          },
+          {
+            "code_action": "included-2"
+          },
+          {
+            "language_server": "ruff"
+          },
+          {
+            "code_action": "included-3"
+          },
+          {
+            "code_action": "included-4"
+          }
+        ]
+      }"#
+                .unindent(),
             ),
         );
     }
@@ -1443,55 +1457,63 @@ mod tests {
     fn test_flatten_code_action_formatters_array_with_multiple_action_blocks_in_languages() {
         assert_migrate_settings(
             &r#"{
-                "languages": {
-                    "Rust": {
-                        "formatter": [
-                          {
-                              "code_actions": {
-                                  "included-1": true,
-                                  "included-2": true,
-                                  "excluded": false,
-                              }
-                          },
-                          {
-                              "language_server": "ruff"
-                          },
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "excluded-2": false,
-                              }
-                          }
-                          // some comment
-                          ,
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "included-3": true,
-                                  "included-4": true,
-                              }
-                          },
-                        ]
-                    }
+        "languages": {
+          "Rust": {
+            "formatter": [
+              {
+                "code_actions": {
+                  "included-1": true,
+                  "included-2": true,
+                  "excluded": false,
                 }
-            }"#
+              },
+              {
+                "language_server": "ruff"
+              },
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "excluded-2": false,
+                }
+              }
+              // some comment
+              ,
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "included-3": true,
+                  "included-4": true,
+                }
+              },
+            ]
+          }
+        }
+      }"#
             .unindent(),
             Some(
                 &r#"{
-                    "languages": {
-                        "Rust": {
-                            "formatter": [
-                              { "code_action": "included-1" },
-                              { "code_action": "included-2" },
-                              {
-                                  "language_server": "ruff"
-                              },
-                              { "code_action": "included-3" },
-                              { "code_action": "included-4" },
-                            ]
-                        }
-                    }
-                }"#
+          "languages": {
+            "Rust": {
+              "formatter": [
+                {
+                  "code_action": "included-1"
+                },
+                {
+                  "code_action": "included-2"
+                },
+                {
+                  "language_server": "ruff"
+                },
+                {
+                  "code_action": "included-3"
+                },
+                {
+                  "code_action": "included-4"
+                }
+              ]
+            }
+          }
+        }"#
                 .unindent(),
             ),
         );
@@ -1502,100 +1524,120 @@ mod tests {
      {
         assert_migrate_settings(
             &r#"{
-                "formatter": {
-                    "code_actions": {
-                        "default-1": true,
-                        "default-2": true,
-                        "default-3": true,
-                        "default-4": true,
-                    }
-                },
-                "languages": {
-                    "Rust": {
-                        "formatter": [
-                          {
-                              "code_actions": {
-                                  "included-1": true,
-                                  "included-2": true,
-                                  "excluded": false,
-                              }
-                          },
-                          {
-                              "language_server": "ruff"
-                          },
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "excluded-2": false,
-                              }
-                          }
-                          // some comment
-                          ,
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "included-3": true,
-                                  "included-4": true,
-                              }
-                          },
-                        ]
-                    },
-                    "Python": {
-                        "formatter": [
-                          {
-                              "language_server": "ruff"
-                          },
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "excluded-2": false,
-                              }
-                          }
-                          // some comment
-                          ,
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "included-3": true,
-                                  "included-4": true,
-                              }
-                          },
-                        ]
-                    }
+        "formatter": {
+          "code_actions": {
+            "default-1": true,
+            "default-2": true,
+            "default-3": true,
+            "default-4": true,
+          }
+        },
+        "languages": {
+          "Rust": {
+            "formatter": [
+              {
+                "code_actions": {
+                  "included-1": true,
+                  "included-2": true,
+                  "excluded": false,
                 }
-            }"#
+              },
+              {
+                "language_server": "ruff"
+              },
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "excluded-2": false,
+                }
+              }
+              // some comment
+              ,
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "included-3": true,
+                  "included-4": true,
+                }
+              },
+            ]
+          },
+          "Python": {
+            "formatter": [
+              {
+                "language_server": "ruff"
+              },
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "excluded-2": false,
+                }
+              }
+              // some comment
+              ,
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "included-3": true,
+                  "included-4": true,
+                }
+              },
+            ]
+          }
+        }
+      }"#
             .unindent(),
             Some(
                 &r#"{
-                    "formatter": [
-                      { "code_action": "default-1" },
-                      { "code_action": "default-2" },
-                      { "code_action": "default-3" },
-                      { "code_action": "default-4" }
-                    ],
-                    "languages": {
-                        "Rust": {
-                            "formatter": [
-                              { "code_action": "included-1" },
-                              { "code_action": "included-2" },
-                              {
-                                  "language_server": "ruff"
-                              },
-                              { "code_action": "included-3" },
-                              { "code_action": "included-4" },
-                            ]
-                        },
-                        "Python": {
-                            "formatter": [
-                              {
-                                  "language_server": "ruff"
-                              },
-                              { "code_action": "included-3" },
-                              { "code_action": "included-4" },
-                            ]
-                        }
-                    }
-                }"#
+          "formatter": [
+            {
+              "code_action": "default-1"
+            },
+            {
+              "code_action": "default-2"
+            },
+            {
+              "code_action": "default-3"
+            },
+            {
+              "code_action": "default-4"
+            }
+          ],
+          "languages": {
+            "Rust": {
+              "formatter": [
+                {
+                  "code_action": "included-1"
+                },
+                {
+                  "code_action": "included-2"
+                },
+                {
+                  "language_server": "ruff"
+                },
+                {
+                  "code_action": "included-3"
+                },
+                {
+                  "code_action": "included-4"
+                }
+              ]
+            },
+            "Python": {
+              "formatter": [
+                {
+                  "language_server": "ruff"
+                },
+                {
+                  "code_action": "included-3"
+                },
+                {
+                  "code_action": "included-4"
+                }
+              ]
+            }
+          }
+        }"#
                 .unindent(),
             ),
         );
@@ -1604,153 +1646,185 @@ mod tests {
     #[test]
     fn test_flatten_code_action_formatters_array_with_format_on_save_and_multiple_languages() {
         assert_migrate_settings_with_migrations(
-            &[MigrationType::TreeSitter(
-                migrations::m_2025_10_01::SETTINGS_PATTERNS,
-                &SETTINGS_QUERY_2025_10_01,
+            &[MigrationType::Json(
+                migrations::m_2025_10_01::flatten_code_actions_formatters,
             )],
             &r#"{
-                "formatter": {
-                    "code_actions": {
-                        "default-1": true,
-                        "default-2": true,
-                        "default-3": true,
-                        "default-4": true,
-                    }
-                },
-                "format_on_save": [
-                  {
-                      "code_actions": {
-                          "included-1": true,
-                          "included-2": true,
-                          "excluded": false,
-                      }
-                  },
-                  {
-                      "language_server": "ruff"
-                  },
-                  {
-                      "code_actions": {
-                          "excluded": false,
-                          "excluded-2": false,
-                      }
-                  }
-                  // some comment
-                  ,
-                  {
-                      "code_actions": {
-                          "excluded": false,
-                          "included-3": true,
-                          "included-4": true,
-                      }
-                  },
-                ],
-                "languages": {
-                    "Rust": {
-                        "format_on_save": "prettier",
-                        "formatter": [
-                          {
-                              "code_actions": {
-                                  "included-1": true,
-                                  "included-2": true,
-                                  "excluded": false,
-                              }
-                          },
-                          {
-                              "language_server": "ruff"
-                          },
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "excluded-2": false,
-                              }
-                          }
-                          // some comment
-                          ,
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "included-3": true,
-                                  "included-4": true,
-                              }
-                          },
-                        ]
-                    },
-                    "Python": {
-                        "format_on_save": {
-                            "code_actions": {
-                                "on-save-1": true,
-                                "on-save-2": true,
-                            }
-                        },
-                        "formatter": [
-                          {
-                              "language_server": "ruff"
-                          },
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "excluded-2": false,
-                              }
-                          }
-                          // some comment
-                          ,
-                          {
-                              "code_actions": {
-                                  "excluded": false,
-                                  "included-3": true,
-                                  "included-4": true,
-                              }
-                          },
-                        ]
-                    }
+        "formatter": {
+          "code_actions": {
+            "default-1": true,
+            "default-2": true,
+            "default-3": true,
+            "default-4": true,
+          }
+        },
+        "format_on_save": [
+          {
+            "code_actions": {
+              "included-1": true,
+              "included-2": true,
+              "excluded": false,
+            }
+          },
+          {
+            "language_server": "ruff"
+          },
+          {
+            "code_actions": {
+              "excluded": false,
+              "excluded-2": false,
+            }
+          }
+          // some comment
+          ,
+          {
+            "code_actions": {
+              "excluded": false,
+              "included-3": true,
+              "included-4": true,
+            }
+          },
+        ],
+        "languages": {
+          "Rust": {
+            "format_on_save": "prettier",
+            "formatter": [
+              {
+                "code_actions": {
+                  "included-1": true,
+                  "included-2": true,
+                  "excluded": false,
                 }
-            }"#
+              },
+              {
+                "language_server": "ruff"
+              },
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "excluded-2": false,
+                }
+              }
+              // some comment
+              ,
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "included-3": true,
+                  "included-4": true,
+                }
+              },
+            ]
+          },
+          "Python": {
+            "format_on_save": {
+              "code_actions": {
+                "on-save-1": true,
+                "on-save-2": true,
+              }
+            },
+            "formatter": [
+              {
+                "language_server": "ruff"
+              },
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "excluded-2": false,
+                }
+              }
+              // some comment
+              ,
+              {
+                "code_actions": {
+                  "excluded": false,
+                  "included-3": true,
+                  "included-4": true,
+                }
+              },
+            ]
+          }
+        }
+      }"#
             .unindent(),
             Some(
-                &r#"{
-                    "formatter": [
-                      { "code_action": "default-1" },
-                      { "code_action": "default-2" },
-                      { "code_action": "default-3" },
-                      { "code_action": "default-4" }
-                    ],
-                    "format_on_save": [
-                      { "code_action": "included-1" },
-                      { "code_action": "included-2" },
-                      {
-                          "language_server": "ruff"
-                      },
-                      { "code_action": "included-3" },
-                      { "code_action": "included-4" },
-                    ],
-                    "languages": {
-                        "Rust": {
-                            "format_on_save": "prettier",
-                            "formatter": [
-                              { "code_action": "included-1" },
-                              { "code_action": "included-2" },
-                              {
-                                  "language_server": "ruff"
-                              },
-                              { "code_action": "included-3" },
-                              { "code_action": "included-4" },
-                            ]
-                        },
-                        "Python": {
-                            "format_on_save": [
-                              { "code_action": "on-save-1" },
-                              { "code_action": "on-save-2" }
-                            ],
-                            "formatter": [
-                              {
-                                  "language_server": "ruff"
-                              },
-                              { "code_action": "included-3" },
-                              { "code_action": "included-4" },
-                            ]
-                        }
-                    }
-                }"#
+                &r#"
+        {
+          "formatter": [
+            {
+              "code_action": "default-1"
+            },
+            {
+              "code_action": "default-2"
+            },
+            {
+              "code_action": "default-3"
+            },
+            {
+              "code_action": "default-4"
+            }
+          ],
+          "format_on_save": [
+            {
+              "code_action": "included-1"
+            },
+            {
+              "code_action": "included-2"
+            },
+            {
+              "language_server": "ruff"
+            },
+            {
+              "code_action": "included-3"
+            },
+            {
+              "code_action": "included-4"
+            }
+          ],
+          "languages": {
+            "Rust": {
+              "format_on_save": "prettier",
+              "formatter": [
+                {
+                  "code_action": "included-1"
+                },
+                {
+                  "code_action": "included-2"
+                },
+                {
+                  "language_server": "ruff"
+                },
+                {
+                  "code_action": "included-3"
+                },
+                {
+                  "code_action": "included-4"
+                }
+              ]
+            },
+            "Python": {
+              "format_on_save": [
+                {
+                  "code_action": "on-save-1"
+                },
+                {
+                  "code_action": "on-save-2"
+                }
+              ],
+              "formatter": [
+                {
+                  "language_server": "ruff"
+                },
+                {
+                  "code_action": "included-3"
+                },
+                {
+                  "code_action": "included-4"
+                }
+              ]
+            }
+          }
+        }"#
                 .unindent(),
             ),
         );
@@ -1952,25 +2026,25 @@ mod tests {
                 migrations::m_2025_10_10::remove_code_actions_on_format,
             )],
             &r#"{
-                "code_actions_on_format": {
-                    "a": true,
-                    "b": false,
-                    "c": true
-                }
-            }"#
+        "code_actions_on_format": {
+          "a": true,
+          "b": false,
+          "c": true
+        }
+      }"#
             .unindent(),
             Some(
                 &r#"{
-                    "formatter": [
-                        {
-                            "code_action": "a"
-                        },
-                        {
-                            "code_action": "c"
-                        }
-                    ]
-                }
-                "#
+          "formatter": [
+            {
+              "code_action": "a"
+            },
+            {
+              "code_action": "c"
+            }
+          ]
+        }
+        "#
                 .unindent(),
             ),
         );
@@ -2163,12 +2237,12 @@ mod tests {
                       ]
                     },
                     "Python": {
-                            "formatter": [
-                                {
-                                    "code_action": "source.organizeImports"
-                                }
-                            ]
+                      "formatter": [
+                        {
+                          "code_action": "source.organizeImports"
                         }
+                      ]
+                    }
                   }
                 }"#
                 .unindent(),
@@ -2212,4 +2286,53 @@ mod tests {
             ),
         );
     }
+
+    #[test]
+    fn test_code_action_formatters_issue() {
+        assert_migrate_settings_with_migrations(
+            &[MigrationType::Json(
+                migrations::m_2025_10_01::flatten_code_actions_formatters,
+            )],
+            &r#"
+    {
+      "languages": {
+        "Python": {
+          "language_servers": ["ruff"],
+          "format_on_save": "on",
+          "formatter": [
+            {
+              "code_actions": {
+                // Fix all auto-fixable lint violations
+                "source.fixAll.ruff": true,
+                // Organize imports
+                "source.organizeImports.ruff": true
+              }
+            }
+          ]
+        }
+      }
+    }"#
+            .unindent(),
+            Some(
+                &r#"
+    {
+      "languages": {
+        "Python": {
+          "language_servers": ["ruff"],
+          "format_on_save": "on",
+          "formatter": [
+            {
+              "code_action": "source.fixAll.ruff"
+            },
+            {
+              "code_action": "source.organizeImports.ruff"
+            }
+          ]
+        }
+      }
+    }"#
+                .unindent(),
+            ),
+        );
+    }
 }
diff --git a/crates/migrator/src/patterns.rs b/crates/migrator/src/patterns.rs
index 3848baf23b..4132c93d93 100644
--- a/crates/migrator/src/patterns.rs
+++ b/crates/migrator/src/patterns.rs
@@ -10,4 +10,5 @@ pub(crate) use settings::{
     SETTINGS_ASSISTANT_PATTERN, SETTINGS_ASSISTANT_TOOLS_PATTERN,
     SETTINGS_DUPLICATED_AGENT_PATTERN, SETTINGS_EDIT_PREDICTIONS_ASSISTANT_PATTERN,
     SETTINGS_LANGUAGES_PATTERN, SETTINGS_NESTED_KEY_VALUE_PATTERN, SETTINGS_ROOT_KEY_VALUE_PATTERN,
+    migrate_language_setting,
 };
diff --git a/crates/migrator/src/patterns/settings.rs b/crates/migrator/src/patterns/settings.rs
index 72fd02b153..a068cce23b 100644
--- a/crates/migrator/src/patterns/settings.rs
+++ b/crates/migrator/src/patterns/settings.rs
@@ -108,3 +108,24 @@ pub const SETTINGS_DUPLICATED_AGENT_PATTERN: &str = r#"(document
     (#eq? @agent1 "agent")
     (#eq? @agent2 "agent")
 )"#;
+
+/// Migrate language settings,
+/// calls `migrate_fn` with the top level object as well as all language settings under the "languages" key
+/// Fails early if `migrate_fn` returns an error at any point
+pub fn migrate_language_setting(
+    value: &mut serde_json::Value,
+    migrate_fn: fn(&mut serde_json::Value, path: &[&str]) -> anyhow::Result<()>,
+) -> anyhow::Result<()> {
+    migrate_fn(value, &[])?;
+    let languages = value
+        .as_object_mut()
+        .and_then(|obj| obj.get_mut("languages"))
+        .and_then(|languages| languages.as_object_mut());
+    if let Some(languages) = languages {
+        for (language_name, language) in languages.iter_mut() {
+            let path = vec!["languages", language_name];
+            migrate_fn(language, &path)?;
+        }
+    }
+    Ok(())
+}
diff --git a/crates/settings/src/settings_json.rs b/crates/settings/src/settings_json.rs
index 555a48e9f0..5e83b11b33 100644
--- a/crates/settings/src/settings_json.rs
+++ b/crates/settings/src/settings_json.rs
@@ -262,8 +262,8 @@ pub fn replace_value_in_json_text<T: AsRef<str>>(
         } else {
             // We don't have the key, construct the nested objects
             let new_value = construct_json_value(&key_path[depth..], new_value);
-            let indent_prefix_len = 4 * depth;
-            let mut new_val = to_pretty_json(&new_value, 4, indent_prefix_len);
+            let indent_prefix_len = tab_size * depth;
+            let mut new_val = to_pretty_json(&new_value, tab_size, indent_prefix_len);
             if depth == 0 {
                 new_val.push('\n');
             }
@@ -628,6 +628,100 @@ pub fn append_top_level_array_value_in_json_text(
     }
 }
 
+/// Infers the indentation size used in JSON text by analyzing the tree structure.
+/// Returns the detected indent size, or a default of 2 if no indentation is found.
+pub fn infer_json_indent_size(text: &str) -> usize {
+    const MAX_INDENT_SIZE: usize = 64;
+
+    let mut parser = tree_sitter::Parser::new();
+    parser
+        .set_language(&tree_sitter_json::LANGUAGE.into())
+        .unwrap();
+
+    let Some(syntax_tree) = parser.parse(text, None) else {
+        return 4;
+    };
+
+    let mut cursor = syntax_tree.walk();
+    let mut indent_counts = [0u32; MAX_INDENT_SIZE];
+
+    // Traverse the tree to find indentation patterns
+    fn visit_node(
+        cursor: &mut tree_sitter::TreeCursor,
+        indent_counts: &mut [u32; MAX_INDENT_SIZE],
+        depth: usize,
+    ) {
+        if depth >= 3 {
+            return;
+        }
+        let node = cursor.node();
+        let node_kind = node.kind();
+
+        // For objects and arrays, check the indentation of their first content child
+        if matches!(node_kind, "object" | "array") {
+            let container_column = node.start_position().column;
+            let container_row = node.start_position().row;
+
+            if cursor.goto_first_child() {
+                // Skip the opening bracket
+                loop {
+                    let child = cursor.node();
+                    let child_kind = child.kind();
+
+                    // Look for the first actual content (pair for objects, value for arrays)
+                    if (node_kind == "object" && child_kind == "pair")
+                        || (node_kind == "array"
+                            && !matches!(child_kind, "[" | "]" | "," | "comment"))
+                    {
+                        let child_column = child.start_position().column;
+                        let child_row = child.start_position().row;
+
+                        // Only count if the child is on a different line
+                        if child_row > container_row && child_column > container_column {
+                            let indent = child_column - container_column;
+                            if indent > 0 && indent < MAX_INDENT_SIZE {
+                                indent_counts[indent] += 1;
+                            }
+                        }
+                        break;
+                    }
+
+                    if !cursor.goto_next_sibling() {
+                        break;
+                    }
+                }
+                cursor.goto_parent();
+            }
+        }
+
+        // Recurse to children
+        if cursor.goto_first_child() {
+            loop {
+                visit_node(cursor, indent_counts, depth + 1);
+                if !cursor.goto_next_sibling() {
+                    break;
+                }
+            }
+            cursor.goto_parent();
+        }
+    }
+
+    visit_node(&mut cursor, &mut indent_counts, 0);
+
+    // Find the indent size with the highest count
+    let mut max_count = 0;
+    let mut max_indent = 4;
+
+    for (indent, &count) in indent_counts.iter().enumerate() {
+        if count > max_count {
+            max_count = count;
+            max_indent = indent;
+        }
+    }
+
+    if max_count == 0 { 2 } else { max_indent }
+}
+
 pub fn to_pretty_json(
     value: &impl Serialize,
     indent_size: usize,
@@ -2486,4 +2580,69 @@ mod tests {
             .unindent(),
         )
     }
+
+    #[test]
+    fn test_infer_json_indent_size() {
+        let json_2_spaces = r#"{
+  "key1": "value1",
+  "nested": {
+    "key2": "value2",
+    "array": [
+      1,
+      2,
+      3
+    ]
+  }
+}"#;
+        assert_eq!(infer_json_indent_size(json_2_spaces), 2);
+
+        let json_4_spaces = r#"{
+    "key1": "value1",
+    "nested": {
+        "key2": "value2",
+        "array": [
+            1,
+            2,
+            3
+        ]
+    }
+}"#;
+        assert_eq!(infer_json_indent_size(json_4_spaces), 4);
+
+        let json_8_spaces = r#"{
+        "key1": "value1",
+        "nested": {
+                "key2": "value2"
+        }
+}"#;
+        assert_eq!(infer_json_indent_size(json_8_spaces), 8);
+
+        let json_single_line = r#"{"key": "value", "nested": {"inner": "data"}}"#;
+        assert_eq!(infer_json_indent_size(json_single_line), 2);
+
+        let json_empty = r#"{}"#;
+        assert_eq!(infer_json_indent_size(json_empty), 2);
+
+        let json_array = r#"[
+  {
+    "id": 1,
+    "name": "first"
+  },
+  {
+    "id": 2,
+    "name": "second"
+  }
+]"#;
+        assert_eq!(infer_json_indent_size(json_array), 2);
+
+        let json_mixed = r#"{
+  "a": {
+    "b": {
+        "c": "value"
+    }
+  },
+  "d": "value2"
+}"#;
+        assert_eq!(infer_json_indent_size(json_mixed), 2);
+    }
 }
diff --git a/crates/settings/src/settings_store.rs b/crates/settings/src/settings_store.rs
index 6f22e27d98..4731c38379 100644
--- a/crates/settings/src/settings_store.rs
+++ b/crates/settings/src/settings_store.rs
@@ -33,6 +33,7 @@ pub type EditorconfigProperties = ec4rs::Properties;
 use crate::{
     ActiveSettingsProfileName, FontFamilyName, IconThemeName, LanguageSettingsContent,
     LanguageToSettingsMap, SettingsJsonSchemaParams, ThemeName, VsCodeSettings, WorktreeId,
+    infer_json_indent_size,
     merge_from::MergeFrom,
     parse_json_with_comments,
     settings_content::{
@@ -637,7 +638,7 @@ impl SettingsStore {
 
         let mut key_path = Vec::new();
         let mut edits = Vec::new();
-        let tab_size = self.json_tab_size();
+        let tab_size = infer_json_indent_size(&text);
         let mut text = text.to_string();
         update_value_in_json_text(
             &mut text,
@@ -650,10 +651,6 @@ impl SettingsStore {
         edits
     }
 
-    pub fn json_tab_size(&self) -> usize {
-        2
-    }
-
     /// Sets the default settings via a JSON string.
     ///
     /// The string should contain a JSON object with a default value for every setting.
@@ -1540,9 +1537,9 @@ mod tests {
                 })
             },
             r#"{
-                "tabs": {
-                    "git_status": true
-                }
+              "tabs": {
+                "git_status": true
+              }
             }
             "#
             .unindent(),
@@ -1557,9 +1554,9 @@ mod tests {
             .unindent(),
             |settings| settings.title_bar.get_or_insert_default().show_branch_name = Some(true),
             r#"{
-                "title_bar": {
-                    "show_branch_name": true
-                }
+              "title_bar": {
+                "show_branch_name": true
+              }
             }
             "#
             .unindent(),
@@ -1584,7 +1581,7 @@ mod tests {
             .unindent(),
             r#" { "editor.tabSize": 37 } "#.to_owned(),
             r#"{
-                "tab_size": 37
+              "tab_size": 37
             }
             "#
             .unindent(),
@@ -1637,9 +1634,9 @@ mod tests {
             .unindent(),
             r#"{ "workbench.editor.decorations.colors": true }"#.to_owned(),
             r#"{
-                "tabs": {
-                    "git_status": true
-                }
+              "tabs": {
+                "git_status": true
+              }
             }
             "#
             .unindent(),
@@ -1655,11 +1652,11 @@ mod tests {
             .unindent(),
             r#"{ "editor.fontFamily": "Cascadia Code, 'Consolas', Courier New" }"#.to_owned(),
             r#"{
-                "buffer_font_fallbacks": [
-                    "Consolas",
-                    "Courier New"
-                ],
-                "buffer_font_family": "Cascadia Code"
+              "buffer_font_fallbacks": [
+                "Consolas",
+                "Courier New"
+              ],
+              "buffer_font_family": "Cascadia Code"
             }
             "#
             .unindent(),
@@ -1695,16 +1692,16 @@ mod tests {
                 .get_or_insert_default()
                 .enabled = Some(true);
         });
-        assert_eq!(
+        pretty_assertions::assert_str_eq!(
             actual,
             r#"{
-            "git": {
+              "git": {
                 "inline_blame": {
-                    "enabled": true
+                  "enabled": true
                 }
+              }
             }
-        }
-        "#
+            "#
             .unindent()
         );
     }