diff --git a/build/bundle.js b/build/bundle.js
index 86a5b05c..a1dd3f4b 100644
--- a/build/bundle.js
+++ b/build/bundle.js
@@ -28136,7 +28136,9 @@ var toGlobalize = {
 };
 
 _.each(toGlobalize, function(module) {
-  _.extend(window, module);
+  for (var key in module) {
+    window['debug_' + key] = module[key];
+  }
 });
 
 $(document).ready(function() {
@@ -28145,6 +28147,7 @@ $(document).ready(function() {
   window.sandbox = toGlobalize.Main.getSandbox();
   window.modules = toGlobalize;
   window.levelDropdown = toGlobalize.Main.getLevelDropdown();
+  window.under = _;
 });
 
 
diff --git a/spec/git.spec.js b/spec/git.spec.js
index a7bcdac9..9d783ca8 100644
--- a/spec/git.spec.js
+++ b/spec/git.spec.js
@@ -1,6 +1,5 @@
 var HeadlessGit = require('../src/js/git/headless').HeadlessGit;
 var TreeCompare = require('../src/js/git/treeCompare').TreeCompare;
-var treeCompare = new TreeCompare();
 
 var loadTree = function(json) {
   return JSON.parse(unescape(json));
@@ -10,7 +9,7 @@ var compareAnswer = function(headless, expectedJSON) {
   var expectedTree = loadTree(expectedJSON);
   var actualTree = headless.gitEngine.exportTree();
 
-  var equal = treeCompare.compareTrees(expectedTree, actualTree);
+  var equal = TreeCompare.compareTrees(expectedTree, actualTree);
   if (!equal) {
     console.log('tree1', expectedTree);
     console.log('tree2', actualTree);
diff --git a/spec/treeCompare.spec.js b/spec/treeCompare.spec.js
new file mode 100644
index 00000000..7f686dd3
--- /dev/null
+++ b/spec/treeCompare.spec.js
@@ -0,0 +1,39 @@
+var TreeCompare = require('../src/js/git/treeCompare').TreeCompare;
+var _ = require('underscore');
+
+var loadTree = function(json) {
+  return JSON.parse(unescape(json));
+};
+
+var copyArgs = function(args) {
+  return _.map(args, function(arg) {
+    return arg;
+  });
+};
+
+var loadTree = function(treeString) {
+  return TreeCompare.convertTreeSafe(treeString);
+};
+
+var testMethod = function(compareMethod, goalTreeString /* other trees */) {
+  if (arguments.length < 3) {
+    throw new Error('not allowed! need at least one tree to compare');
+  }
+
+  var toCompare = copyArgs(arguments).slice(2);
+  _.each(toCompare, function(actualTree) {
+    var isEqual = TreeCompare.dispatch(compareMethod, goalTreeString, actualTree);
+    if (!isEqual) {
+      console.log('this goal tree', loadTree(goalTreeString));
+      console.log('did not match this tree', loadTree(actualTree));
+    }
+    expect(isEqual).toBe(true);
+  });
+};
+
+describe('Tree Compare', function() {
+  it('can compare only master', function() {
+
+  });
+});
+
diff --git a/src/js/git/treeCompare.js b/src/js/git/treeCompare.js
index bc9731fa..05d2bfb6 100644
--- a/src/js/git/treeCompare.js
+++ b/src/js/git/treeCompare.js
@@ -3,6 +3,29 @@ var _ = require('underscore');
 // static class...
 var TreeCompare = {};
 
+TreeCompare.dispatchFromLevel = function(levelBlob, treeToCompare) {
+  var goalTreeString = levelBlob.goalTreeString;
+  return TreeCompare.dispatch(levelBlob, goalTreeString, treeToCompare);
+};
+
+TreeCompare.dispatch = function(levelBlob, goalTreeString, treeToCompare) {
+  switch(true) {
+    case !!levelBlob.compareOnlyMaster:
+      return TreeCompare.compareBranchWithinTrees(current, goalTreeString, 'master');
+    case !!levelBlob.compareOnlyBranches:
+      return TreeCompare.compareAllBranchesWithinTrees(current, goalTreeString);
+    case !!levelBlob.compareAllBranchesHashAgnostic:
+      return TreeCompare.compareAllBranchesWithinTreesHashAgnostic(current, goalTreeString);
+    case !!levelBlob.compareOnlyMasterHashAgnostic:
+      return TreeCompare.compareBranchesWithinTreesHashAgnostic(current, goalTreeString, ['master']);
+    case !!levelBlob.compareOnlyMasterHashAgnosticWithAsserts:
+      return TreeCompare.compareBranchesWithinTreesHashAgnostic(current, goalTreeString, ['master']) &&
+        TreeCompare.evalAsserts(current, levelBlob.goalAsserts);
+    default:
+      return TreeCompare.compareAllBranchesWithinTreesAndHEAD(current, goalTreeString);
+  }
+};
+
 // would love to have copy properties here.. :(
 TreeCompare.compareAllBranchesWithinTreesAndHEAD = function(treeA, treeB) {
   treeA = this.convertTreeSafe(treeA);
diff --git a/src/js/util/debug.js b/src/js/util/debug.js
index 2b562c03..ed3b2b22 100644
--- a/src/js/util/debug.js
+++ b/src/js/util/debug.js
@@ -28,7 +28,9 @@ var toGlobalize = {
 };
 
 _.each(toGlobalize, function(module) {
-  _.extend(window, module);
+  for (var key in module) {
+    window['debug_' + key] = module[key];
+  }
 });
 
 $(document).ready(function() {
@@ -37,5 +39,6 @@ $(document).ready(function() {
   window.sandbox = toGlobalize.Main.getSandbox();
   window.modules = toGlobalize;
   window.levelDropdown = toGlobalize.Main.getLevelDropdown();
+  window.under = _;
 });