diff --git a/nixd/include/nixd/Controller/Controller.h b/nixd/include/nixd/Controller/Controller.h
index 4690e613a..798fabe3f 100644
--- a/nixd/include/nixd/Controller/Controller.h
+++ b/nixd/include/nixd/Controller/Controller.h
@@ -74,6 +74,13 @@ class Controller : public lspserver::LSPServer {
   void
   createWorkDoneProgress(const lspserver::WorkDoneProgressCreateParams &Params);
 
+  /// Request the client to show a document (file or URL).
+  /// @since LSP 3.16.0
+  llvm::unique_function<void(
+      const lspserver::ShowDocumentParams &,
+      lspserver::Callback<lspserver::ShowDocumentResult>)>
+      ShowDocument;
+
   llvm::unique_function<void(
       const lspserver::ProgressParams<lspserver::WorkDoneProgressBegin> &)>
       BeginWorkDoneProgress;
@@ -165,6 +172,9 @@ class Controller : public lspserver::LSPServer {
   onCodeAction(const lspserver::CodeActionParams &Params,
                lspserver::Callback<std::vector<lspserver::CodeAction>> Reply);
 
+  void onCodeActionResolve(const lspserver::CodeAction &Params,
+                           lspserver::Callback<lspserver::CodeAction> Reply);
+
   void onHover(const lspserver::TextDocumentPositionParams &Params,
                lspserver::Callback<std::optional<lspserver::Hover>> Reply);
 
diff --git a/nixd/lib/Controller/CodeAction.cpp b/nixd/lib/Controller/CodeAction.cpp
index 249098862..0a66bd079 100644
--- a/nixd/lib/Controller/CodeAction.cpp
+++ b/nixd/lib/Controller/CodeAction.cpp
@@ -9,6 +9,8 @@
 #include "nixd/Controller/Controller.h"
 
 #include <nixf/Basic/Nodes/Attrs.h>
+#include <nixf/Basic/Nodes/Expr.h>
+#include <nixf/Basic/Nodes/Simple.h>
 #include <nixf/Sema/ParentMap.h>
 
 #include <boost/asio/post.hpp>
@@ -634,6 +636,85 @@ void addAttrNameActions(const nixf::Node &N, const nixf::ParentMapAnalysis &PM,
   }
 }
 
+/// \brief Construct noogle.dev URL for a lib.* function path.
+/// Examples:
+///   - {"lib", "optionalString"} -> "https://noogle.dev/f/lib/optionalString"
+///   - {"lib", "strings", "optionalString"} ->
+///   "https://noogle.dev/f/lib/strings/optionalString"
+std::string buildNoogleUrl(const std::vector<std::string> &Path) {
+  std::string Url = "https://noogle.dev/f";
+  for (const auto &Segment : Path) {
+    Url += "/";
+    Url += Segment;
+  }
+  return Url;
+}
+
+/// \brief Add a code action to open noogle.dev documentation for lib.*
+/// functions.
+///
+/// This action is offered when the cursor is on an ExprSelect with:
+///   - Base expression is ExprVar with name "lib"
+///   - Path contains at least one static attribute name
+///
+/// Examples that trigger:
+///   - lib.optionalString
+///   - lib.strings.optionalString
+///   - lib.attrsets.mapAttrs
+///
+/// Examples that do NOT trigger:
+///   - lib (just the variable, no selection)
+///   - lib.${x} (dynamic attribute)
+///   - pkgs.hello (not lib.*)
+void addNoogleDocAction(const nixf::Node &N, const nixf::ParentMapAnalysis &PM,
+                        std::vector<CodeAction> &Actions) {
+  // Find if we're inside an ExprSelect
+  const nixf::Node *SelectNode = PM.upTo(N, nixf::Node::NK_ExprSelect);
+  if (!SelectNode)
+    return;
+
+  const auto &Sel = static_cast<const nixf::ExprSelect &>(*SelectNode);
+
+  // Check base expression is ExprVar with name "lib"
+  if (Sel.expr().kind() != nixf::Node::NK_ExprVar)
+    return;
+
+  const auto &Var = static_cast<const nixf::ExprVar &>(Sel.expr());
+  if (Var.id().name() != "lib")
+    return;
+
+  // Check path exists and has at least one attribute
+  if (!Sel.path())
+    return;
+
+  const nixf::AttrPath &Path = *Sel.path();
+  if (Path.names().empty())
+    return;
+
+  // Build the function path, checking all names are static
+  std::vector<std::string> FunctionPath;
+  FunctionPath.reserve(Path.names().size() + 1);
+  FunctionPath.emplace_back("lib");
+
+  for (const auto &Name : Path.names()) {
+    if (!Name->isStatic())
+      return; // Dynamic attribute, can't construct URL
+    FunctionPath.emplace_back(Name->staticName());
+  }
+
+  // Construct the noogle.dev URL
+  std::string NoogleUrl = buildNoogleUrl(FunctionPath);
+
+  // Create a code action that will open the URL
+  // Note: The actual URL opening is handled by the client via
+  // window/showDocument
+  Actions.emplace_back(CodeAction{
+      .title = "Open Noogle documentation for " + FunctionPath.back(),
+      .kind = std::string(CodeAction::REFACTOR_KIND),
+      .data = Object{{"noogleUrl", NoogleUrl}},
+  });
+}
+
 /// \brief Add JSON to Nix conversion action for selected JSON text.
 /// This is a selection-based action that works on arbitrary text, not AST
 /// nodes.
@@ -694,7 +775,6 @@ void addJsonToNixAction(llvm::StringRef Src, const lspserver::Range &Range,
       "Convert JSON to Nix", CodeAction::REFACTOR_REWRITE_KIND, FileURI, Range,
       std::move(NixText)));
 }
-
 } // namespace
 
 void Controller::onCodeAction(const lspserver::CodeActionParams &Params,
@@ -746,6 +826,7 @@ void Controller::onCodeAction(const lspserver::CodeActionParams &Params,
           addFlattenAttrsAction(*N, *TU->parentMap(), FileURI, TU->src(),
                                 Actions);
           addPackAttrsAction(*N, *TU->parentMap(), FileURI, TU->src(), Actions);
+          addNoogleDocAction(*N, *TU->parentMap(), Actions);
         }
       }
 
@@ -758,4 +839,36 @@ void Controller::onCodeAction(const lspserver::CodeActionParams &Params,
   boost::asio::post(Pool, std::move(Action));
 }
 
+void Controller::onCodeActionResolve(const lspserver::CodeAction &Params,
+                                     Callback<CodeAction> Reply) {
+  auto Action = [Reply = std::move(Reply), Params, this]() mutable {
+    // Check if this is a Noogle documentation action
+    if (Params.data) {
+      const auto *DataObj = Params.data->getAsObject();
+      if (DataObj) {
+        auto NoogleUrl = DataObj->getString("noogleUrl");
+        if (NoogleUrl) {
+          // Call window/showDocument to open the URL in external browser
+          ShowDocumentParams ShowParams;
+          ShowParams.externalUri = NoogleUrl->str();
+          ShowParams.external = true;
+
+          ShowDocument(
+              ShowParams, [](llvm::Expected<ShowDocumentResult> Result) {
+                if (!Result) {
+                  lspserver::elog("Failed to open Noogle documentation: {0}",
+                                  Result.takeError());
+                }
+              });
+        }
+      }
+    }
+
+    // Return the resolved code action (unchanged for Noogle actions since
+    // the work is done via showDocument)
+    Reply(Params);
+  };
+  boost::asio::post(Pool, std::move(Action));
+}
+
 } // namespace nixd
diff --git a/nixd/lib/Controller/LifeTime.cpp b/nixd/lib/Controller/LifeTime.cpp
index 4f365a6ec..0aac76dbc 100644
--- a/nixd/lib/Controller/LifeTime.cpp
+++ b/nixd/lib/Controller/LifeTime.cpp
@@ -98,9 +98,10 @@ void Controller::
        {
            "codeActionProvider",
            Object{
-               {"codeActionKinds", Array{CodeAction::QUICKFIX_KIND,
-                                         CodeAction::REFACTOR_REWRITE_KIND}},
-               {"resolveProvider", false},
+               {"codeActionKinds",
+                Array{CodeAction::QUICKFIX_KIND, CodeAction::REFACTOR_KIND,
+                      CodeAction::REFACTOR_REWRITE_KIND}},
+               {"resolveProvider", true},
            },
        },
        {"definitionProvider", true},
diff --git a/nixd/lib/Controller/Support.cpp b/nixd/lib/Controller/Support.cpp
index 2b04592c0..d9c1670b2 100644
--- a/nixd/lib/Controller/Support.cpp
+++ b/nixd/lib/Controller/Support.cpp
@@ -107,6 +107,8 @@ Controller::Controller(std::unique_ptr<lspserver::InboundPort> In,
                      &Controller::onDocumentLink);
   Registry.addMethod("textDocument/codeAction", this,
                      &Controller::onCodeAction);
+  Registry.addMethod("codeAction/resolve", this,
+                     &Controller::onCodeActionResolve);
   Registry.addMethod("textDocument/hover", this, &Controller::onHover);
   Registry.addMethod("textDocument/formatting", this, &Controller::onFormat);
   Registry.addMethod("textDocument/rename", this, &Controller::onRename);
@@ -125,6 +127,8 @@ Controller::Controller(std::unique_ptr<lspserver::InboundPort> In,
   CreateWorkDoneProgress =
       mkOutMethod<WorkDoneProgressCreateParams, std::nullptr_t>(
           "window/workDoneProgress/create");
+  ShowDocument = mkOutMethod<ShowDocumentParams, ShowDocumentResult>(
+      "window/showDocument");
   BeginWorkDoneProgress =
       mkOutNotifiction<ProgressParams<WorkDoneProgressBegin>>("$/progress");
   ReportWorkDoneProgress =
diff --git a/nixd/lspserver/include/lspserver/Protocol.h b/nixd/lspserver/include/lspserver/Protocol.h
index 8e6679e6a..c2160af0d 100644
--- a/nixd/lspserver/include/lspserver/Protocol.h
+++ b/nixd/lspserver/include/lspserver/Protocol.h
@@ -1072,8 +1072,14 @@ struct CodeAction {
   /// A command this code action executes. If a code action provides an edit
   /// and a command, first the edit is executed and then the command.
   std::optional<Command> command;
+
+  /// A data entry field that is preserved on a code action between a
+  /// `textDocument/codeAction` and a `codeAction/resolve` request.
+  /// @since LSP 3.16.0
+  std::optional<llvm::json::Value> data;
 };
 llvm::json::Value toJSON(const CodeAction &);
+bool fromJSON(const llvm::json::Value &, CodeAction &, llvm::json::Path);
 
 /// Represents programming constructs like variables, classes, interfaces etc.
 /// that appear in a document. Document symbols can be hierarchical and they
@@ -1159,6 +1165,42 @@ struct ApplyWorkspaceEditResponse {
 bool fromJSON(const llvm::json::Value &, ApplyWorkspaceEditResponse &,
               llvm::json::Path);
 
+/// Parameters for the `window/showDocument` request.
+/// @since LSP 3.16.0
+struct ShowDocumentParams {
+  /// The document URI to show (for file:// URIs).
+  URIForFile uri;
+
+  /// External URI string (for https:// or other non-file URIs).
+  /// When set, this takes precedence over `uri` in serialization.
+  std::optional<std::string> externalUri;
+
+  /// Indicates to show the resource in an external program.
+  /// To show, for example, `https://noogle.dev/` in the default web browser,
+  /// set `external` to `true`.
+  std::optional<bool> external;
+
+  /// An optional property to indicate whether the editor showing the document
+  /// should take focus or not. Clients might ignore this property if an
+  /// external program is started.
+  std::optional<bool> takeFocus;
+
+  /// An optional selection range if the document is a text document.
+  /// Clients might ignore the property if an external program is started or
+  /// the file is not a text file.
+  std::optional<Range> selection;
+};
+llvm::json::Value toJSON(const ShowDocumentParams &);
+
+/// Result of the `window/showDocument` request.
+/// @since LSP 3.16.0
+struct ShowDocumentResult {
+  /// A boolean indicating if the show was successful.
+  bool success = false;
+};
+bool fromJSON(const llvm::json::Value &, ShowDocumentResult &,
+              llvm::json::Path);
+
 struct TextDocumentPositionParams {
   /// The text document.
   TextDocumentIdentifier textDocument;
diff --git a/nixd/lspserver/src/Protocol.cpp b/nixd/lspserver/src/Protocol.cpp
index 19c2b190f..8f665e989 100644
--- a/nixd/lspserver/src/Protocol.cpp
+++ b/nixd/lspserver/src/Protocol.cpp
@@ -782,9 +782,29 @@ llvm::json::Value toJSON(const CodeAction &CA) {
     CodeAction["edit"] = *CA.edit;
   if (CA.command)
     CodeAction["command"] = *CA.command;
+  if (CA.data)
+    CodeAction["data"] = *CA.data;
   return CodeAction;
 }
 
+bool fromJSON(const llvm::json::Value &Params, CodeAction &CA,
+              llvm::json::Path P) {
+  llvm::json::ObjectMapper O(Params, P);
+  if (!O || !O.map("title", CA.title))
+    return false;
+  O.map("kind", CA.kind);
+  O.map("diagnostics", CA.diagnostics);
+  O.map("isPreferred", CA.isPreferred);
+  O.map("edit", CA.edit);
+  O.map("command", CA.command);
+  // Handle data field - it's an arbitrary JSON value
+  if (const auto *Obj = Params.getAsObject()) {
+    if (const auto *Data = Obj->get("data"))
+      CA.data = *Data;
+  }
+  return true;
+}
+
 llvm::raw_ostream &operator<<(llvm::raw_ostream &O, const DocumentSymbol &S) {
   return O << S.name << " - " << toJSON(S);
 }
@@ -847,6 +867,28 @@ bool fromJSON(const llvm::json::Value &Response, ApplyWorkspaceEditResponse &R,
          O.map("failureReason", R.failureReason);
 }
 
+llvm::json::Value toJSON(const ShowDocumentParams &Params) {
+  llvm::json::Object Result;
+  // Use externalUri if set (for https:// etc), otherwise use uri (for file://)
+  if (Params.externalUri)
+    Result["uri"] = *Params.externalUri;
+  else
+    Result["uri"] = Params.uri;
+  if (Params.external)
+    Result["external"] = *Params.external;
+  if (Params.takeFocus)
+    Result["takeFocus"] = *Params.takeFocus;
+  if (Params.selection)
+    Result["selection"] = *Params.selection;
+  return Result;
+}
+
+bool fromJSON(const llvm::json::Value &Response, ShowDocumentResult &R,
+              llvm::json::Path P) {
+  llvm::json::ObjectMapper O(Response, P);
+  return O && O.map("success", R.success);
+}
+
 bool fromJSON(const llvm::json::Value &Params, TextDocumentPositionParams &R,
               llvm::json::Path P) {
   llvm::json::ObjectMapper O(Params, P);
diff --git a/nixd/tools/nixd/test/code-action/noogle-lib-nested.md b/nixd/tools/nixd/test/code-action/noogle-lib-nested.md
new file mode 100644
index 000000000..e134d0ae0
--- /dev/null
+++ b/nixd/tools/nixd/test/code-action/noogle-lib-nested.md
@@ -0,0 +1,69 @@
+# RUN: nixd --lit-test < %s | FileCheck %s
+
+<-- initialize(0)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":0,
+   "method":"initialize",
+   "params":{
+      "processId":123,
+      "rootPath":"",
+      "capabilities":{
+      },
+      "trace":"off"
+   }
+}
+```
+
+
+<-- textDocument/didOpen
+
+```nix file:///noogle-lib-nested.nix
+lib.strings.optionalString
+```
+
+<-- textDocument/codeAction(2)
+
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":2,
+   "method":"textDocument/codeAction",
+   "params":{
+      "textDocument":{
+         "uri":"file:///noogle-lib-nested.nix"
+      },
+      "range":{
+         "start":{
+            "line": 0,
+            "character":12
+         },
+         "end":{
+            "line":0,
+            "character":26
+         }
+      },
+      "context":{
+         "diagnostics":[],
+         "triggerKind":2
+      }
+   }
+}
+```
+
+```
+     CHECK:   "id": 2,
+CHECK-NEXT:   "jsonrpc": "2.0",
+     CHECK:   "data": {
+CHECK-NEXT:     "noogleUrl": "https://noogle.dev/f/lib/strings/optionalString"
+CHECK-NEXT:   },
+CHECK-NEXT:   "kind": "refactor",
+CHECK-NEXT:   "title": "Open Noogle documentation for optionalString"
+```
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```
diff --git a/nixd/tools/nixd/test/code-action/noogle-lib-simple.md b/nixd/tools/nixd/test/code-action/noogle-lib-simple.md
new file mode 100644
index 000000000..df3f2ff29
--- /dev/null
+++ b/nixd/tools/nixd/test/code-action/noogle-lib-simple.md
@@ -0,0 +1,73 @@
+# RUN: nixd --lit-test < %s | FileCheck %s
+
+<-- initialize(0)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":0,
+   "method":"initialize",
+   "params":{
+      "processId":123,
+      "rootPath":"",
+      "capabilities":{
+      },
+      "trace":"off"
+   }
+}
+```
+
+
+<-- textDocument/didOpen
+
+```nix file:///noogle-lib-simple.nix
+lib.optionalString
+```
+
+<-- textDocument/codeAction(2)
+
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":2,
+   "method":"textDocument/codeAction",
+   "params":{
+      "textDocument":{
+         "uri":"file:///noogle-lib-simple.nix"
+      },
+      "range":{
+         "start":{
+            "line": 0,
+            "character":0
+         },
+         "end":{
+            "line":0,
+            "character":18
+         }
+      },
+      "context":{
+         "diagnostics":[],
+         "triggerKind":2
+      }
+   }
+}
+```
+
+```
+     CHECK:   "id": 2,
+CHECK-NEXT:   "jsonrpc": "2.0",
+CHECK-NEXT:   "result": [
+CHECK-NEXT:     {
+CHECK-NEXT:       "data": {
+CHECK-NEXT:         "noogleUrl": "https://noogle.dev/f/lib/optionalString"
+CHECK-NEXT:       },
+CHECK-NEXT:       "kind": "refactor",
+CHECK-NEXT:       "title": "Open Noogle documentation for optionalString"
+CHECK-NEXT:     }
+CHECK-NEXT:   ]
+```
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```
diff --git a/nixd/tools/nixd/test/code-action/noogle-lib-var-only.md b/nixd/tools/nixd/test/code-action/noogle-lib-var-only.md
new file mode 100644
index 000000000..78343dd3d
--- /dev/null
+++ b/nixd/tools/nixd/test/code-action/noogle-lib-var-only.md
@@ -0,0 +1,67 @@
+# RUN: nixd --lit-test < %s | FileCheck %s
+
+# Test that Noogle action is NOT offered for just "lib" variable without selection
+
+<-- initialize(0)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":0,
+   "method":"initialize",
+   "params":{
+      "processId":123,
+      "rootPath":"",
+      "capabilities":{
+      },
+      "trace":"off"
+   }
+}
+```
+
+
+<-- textDocument/didOpen
+
+```nix file:///noogle-lib-var-only.nix
+lib
+```
+
+<-- textDocument/codeAction(2)
+
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":2,
+   "method":"textDocument/codeAction",
+   "params":{
+      "textDocument":{
+         "uri":"file:///noogle-lib-var-only.nix"
+      },
+      "range":{
+         "start":{
+            "line": 0,
+            "character":0
+         },
+         "end":{
+            "line":0,
+            "character":3
+         }
+      },
+      "context":{
+         "diagnostics":[],
+         "triggerKind":2
+      }
+   }
+}
+```
+
+```
+     CHECK:   "id": 2,
+CHECK-NEXT:   "jsonrpc": "2.0",
+CHECK-NEXT:   "result": []
+```
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```
diff --git a/nixd/tools/nixd/test/code-action/noogle-not-lib.md b/nixd/tools/nixd/test/code-action/noogle-not-lib.md
new file mode 100644
index 000000000..56fb0b8f9
--- /dev/null
+++ b/nixd/tools/nixd/test/code-action/noogle-not-lib.md
@@ -0,0 +1,67 @@
+# RUN: nixd --lit-test < %s | FileCheck %s
+
+# Test that Noogle action is NOT offered for non-lib selects
+
+<-- initialize(0)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":0,
+   "method":"initialize",
+   "params":{
+      "processId":123,
+      "rootPath":"",
+      "capabilities":{
+      },
+      "trace":"off"
+   }
+}
+```
+
+
+<-- textDocument/didOpen
+
+```nix file:///noogle-not-lib.nix
+pkgs.hello
+```
+
+<-- textDocument/codeAction(2)
+
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":2,
+   "method":"textDocument/codeAction",
+   "params":{
+      "textDocument":{
+         "uri":"file:///noogle-not-lib.nix"
+      },
+      "range":{
+         "start":{
+            "line": 0,
+            "character":5
+         },
+         "end":{
+            "line":0,
+            "character":10
+         }
+      },
+      "context":{
+         "diagnostics":[],
+         "triggerKind":2
+      }
+   }
+}
+```
+
+```
+     CHECK:   "id": 2,
+CHECK-NEXT:   "jsonrpc": "2.0",
+ CHECK-NOT:   "noogleUrl"
+```
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```
diff --git a/nixd/tools/nixd/test/initialize.md b/nixd/tools/nixd/test/initialize.md
index 71d1a56a4..4130957a1 100644
--- a/nixd/tools/nixd/test/initialize.md
+++ b/nixd/tools/nixd/test/initialize.md
@@ -29,9 +29,10 @@ CHECK-NEXT:     "capabilities": {
 CHECK-NEXT:       "codeActionProvider": {
 CHECK-NEXT:         "codeActionKinds": [
 CHECK-NEXT:           "quickfix",
+CHECK-NEXT:           "refactor",
 CHECK-NEXT:           "refactor.rewrite"
 CHECK-NEXT:         ],
-CHECK-NEXT:         "resolveProvider": false
+CHECK-NEXT:         "resolveProvider": true
 CHECK-NEXT:       },
 CHECK-NEXT:       "completionProvider": {
 CHECK-NEXT:         "resolveProvider": true,
diff --git a/nixd/tools/nixd/test/semantic-tokens/initialize.md b/nixd/tools/nixd/test/semantic-tokens/initialize.md
index e303bad79..939d2bf5d 100644
--- a/nixd/tools/nixd/test/semantic-tokens/initialize.md
+++ b/nixd/tools/nixd/test/semantic-tokens/initialize.md
@@ -29,9 +29,10 @@ CHECK-NEXT:     "capabilities": {
 CHECK-NEXT:       "codeActionProvider": {
 CHECK-NEXT:         "codeActionKinds": [
 CHECK-NEXT:           "quickfix",
+CHECK-NEXT:           "refactor",
 CHECK-NEXT:           "refactor.rewrite"
 CHECK-NEXT:         ],
-CHECK-NEXT:         "resolveProvider": false
+CHECK-NEXT:         "resolveProvider": true
 CHECK-NEXT:       },
 CHECK-NEXT:       "completionProvider": {
 CHECK-NEXT:         "resolveProvider": true,