diff --git a/CHANGELOG.md b/CHANGELOG.md
index 543e509e0..d43b4b5e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,7 +14,9 @@
 
 #### :bug: Bug fix
 
-- Fix Code Analyzer binary lookup for ReScript v12+ projects.
+- Fix Code Analyzer cwd/binary lookup in monorepos (run from workspace root).
+- Fix monorepo build detection by only watching the workspace root `.compiler.log`.
+- Fix Start Build for ReScript v12+ projects by preferring `rescript.exe`.
 - Take namespace into account for incremental cleanup. https://github.com/rescript-lang/rescript-vscode/pull/1164
 - Potential race condition in incremental compilation. https://github.com/rescript-lang/rescript-vscode/pull/1167
 - Fix extension crash triggered by incremental compilation. https://github.com/rescript-lang/rescript-vscode/pull/1169
diff --git a/client/src/commands/code_analysis.ts b/client/src/commands/code_analysis.ts
index 559f89c67..ed9feafd0 100644
--- a/client/src/commands/code_analysis.ts
+++ b/client/src/commands/code_analysis.ts
@@ -213,9 +213,14 @@ export const runCodeAnalysisWithReanalyze = (
   let currentDocument = window.activeTextEditor.document;
   let cwd = targetDir ?? path.dirname(currentDocument.uri.fsPath);
 
+  // Resolve the project root from `cwd` (which is the workspace root when code analysis is started),
+  // rather than from the currently-open file (which may be in a subpackage).
   let projectRootPath: NormalizedPath | null = findProjectRootOfFileInDir(
-    currentDocument.uri.fsPath,
+    path.join(cwd, "bsconfig.json"),
   );
+  if (projectRootPath == null) {
+    projectRootPath = findProjectRootOfFileInDir(currentDocument.uri.fsPath);
+  }
 
   // Try v12+ path first: @rescript/{platform}-{arch}/bin/rescript-tools.exe
   // Then fall back to legacy paths via getBinaryPath
diff --git a/client/src/extension.ts b/client/src/extension.ts
index c31a8d170..41e7ecc66 100644
--- a/client/src/extension.ts
+++ b/client/src/extension.ts
@@ -442,12 +442,11 @@ export function activate(context: ExtensionContext) {
 
     inCodeAnalysisState.active = true;
 
-    // Pointing reanalyze to the dir of the current file path is fine, because
-    // reanalyze will walk upwards looking for a bsconfig.json in order to find
-    // the correct project root.
-    inCodeAnalysisState.activatedFromDirectory = path.dirname(
-      currentDocument.uri.fsPath,
-    );
+    // Run reanalyze from the workspace root (so monorepos consistently analyze the root project),
+    // instead of from whatever file happened to be active when analysis was started.
+    const wsFolder = workspace.getWorkspaceFolder(currentDocument.uri);
+    inCodeAnalysisState.activatedFromDirectory =
+      wsFolder?.uri.fsPath ?? path.dirname(currentDocument.uri.fsPath);
 
     codeAnalysisRunningStatusBarItem.command =
       "rescript-vscode.stop_code_analysis";
diff --git a/server/src/server.ts b/server/src/server.ts
index b4445f68a..8dad29ea8 100644
--- a/server/src/server.ts
+++ b/server/src/server.ts
@@ -118,16 +118,28 @@ let findRescriptBinary = async (
 ): Promise<utils.NormalizedPath | null> => {
   if (
     config.extensionConfiguration.binaryPath != null &&
-    fs.existsSync(
-      path.join(config.extensionConfiguration.binaryPath, "rescript"),
-    )
+    (fs.existsSync(
+      path.join(config.extensionConfiguration.binaryPath, "rescript.exe"),
+    ) ||
+      fs.existsSync(
+        path.join(config.extensionConfiguration.binaryPath, "rescript"),
+      ))
   ) {
     return utils.normalizePath(
-      path.join(config.extensionConfiguration.binaryPath, "rescript"),
+      fs.existsSync(
+        path.join(config.extensionConfiguration.binaryPath, "rescript.exe"),
+      )
+        ? path.join(config.extensionConfiguration.binaryPath, "rescript.exe")
+        : path.join(config.extensionConfiguration.binaryPath, "rescript"),
     );
   }
 
-  return utils.findRescriptBinary(projectRootPath);
+  // Prefer the native rescript.exe (v12+) for spawning `build -w`.
+  // Fall back to the legacy/JS wrapper `rescript` path if needed.
+  return (
+    (await utils.findRescriptExeBinary(projectRootPath)) ??
+    (await utils.findRescriptBinary(projectRootPath))
+  );
 };
 
 let createInterfaceRequest = new v.RequestType<
@@ -1388,11 +1400,10 @@ async function onMessage(msg: p.Message) {
       const watchers = Array.from(workspaceFolders).flatMap(
         (projectRootPath) => [
           {
-            globPattern: path.join(
-              projectRootPath,
-              "**",
-              c.compilerLogPartialPath,
-            ),
+            // Only watch the root compiler log for each workspace folder.
+            // In monorepos, `**/lib/bs/.compiler.log` matches every package and dependency,
+            // causing a burst of events per save.
+            globPattern: path.join(projectRootPath, c.compilerLogPartialPath),
             kind: p.WatchKind.Change | p.WatchKind.Create | p.WatchKind.Delete,
           },
           {