diff --git a/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee b/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee
index f51d1ed41e..b2257099b4 100644
--- a/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee
+++ b/services/web/public/coffee/ide/editor/directives/aceEditor/track-changes/TrackChangesManager.coffee
@@ -73,16 +73,24 @@ define [
 						_scrollTimeout = null
 					, 200
 
+			@_resetCutState()
+			onCut = () => @onCut()
+			onPaste = () => @onPaste()
+
 			bindToAce = () =>
 				@editor.on "changeSelection", onChangeSelection
 				@editor.on "change", onChangeSelection # Selection also moves with updates elsewhere in the document
 				@editor.on "changeSession", onChangeSession
+				@editor.on "cut", onCut
+				@editor.on "paste", onPaste
 				@editor.renderer.on "resize", onResize
 
 			unbindFromAce = () =>
 				@editor.off "changeSelection", onChangeSelection
 				@editor.off "change", onChangeSelection
 				@editor.off "changeSession", onChangeSession
+				@editor.off "cut", onCut
+				@editor.off "paste", onPaste
 				@editor.renderer.off "resize", onResize
 
 			@$scope.$watch "trackChangesEnabled", (enabled) =>
@@ -244,6 +252,50 @@ define [
 					@_onCommentAdded(comment)
 			@broadcastChange()
 
+		_resetCutState: () ->
+			@_cutState = {
+				text: null
+				comments: []
+				docId: null
+			}
+
+		onCut: () ->
+			@_resetCutState()
+			selection = @editor.getSelectionRange()
+			selection_start = @_aceRangeToShareJs(selection.start)
+			selection_end = @_aceRangeToShareJs(selection.end)
+			@_cutState.text = @editor.getSelectedText()
+			@_cutState.docId = @$scope.docId
+			for comment in @rangesTracker.comments
+				comment_start = comment.op.p
+				comment_end = comment_start + comment.op.c.length
+				if selection_start <= comment_start and comment_end <= selection_end
+					@_cutState.comments.push {
+						offset: comment.op.p - selection_start
+						text: comment.op.c
+						comment: comment
+					}
+
+		onPaste: () =>
+			@editor.once "change", (change) =>
+				return if change.action != "insert"
+				pasted_text = change.lines.join("\n")
+				paste_offset = @_aceRangeToShareJs(change.start)
+				console.log "PASTE", pasted_text, paste_offset
+				# We have to wait until the change has been processed by the range tracker, 
+				# since if we move the ops into place beforehand, they will be moved again
+				# when the changes are processed by the range tracker. This ranges:dirty
+				# event is fired after the doc has applied the changes to the range tracker.
+				@$scope.sharejsDoc.on "ranges:dirty.paste", () =>
+					@$scope.sharejsDoc.off "ranges:dirty.paste" # Doc event emitter uses namespaced events
+					if pasted_text == @_cutState.text and @$scope.docId == @_cutState.docId
+						for {comment, offset, text} in @_cutState.comments
+							op = { c: text, p: paste_offset + offset, t: comment.id }
+							@$scope.sharejsDoc.submitOp op # Resubmitting an existing comment op (by thread id) will move it
+					@_resetCutState()
+					# Check that comments still match text. Will throw error if not.
+					@rangesTracker.validate(@editor.getValue())
+
 		checkMapping: () ->
 			# TODO: reintroduce this check
 			session = @editor.getSession()
diff --git a/services/web/public/coffee/ide/review-panel/RangesTracker.coffee b/services/web/public/coffee/ide/review-panel/RangesTracker.coffee
index a9c43e9816..14193f628d 100644
--- a/services/web/public/coffee/ide/review-panel/RangesTracker.coffee
+++ b/services/web/public/coffee/ide/review-panel/RangesTracker.coffee
@@ -1,3 +1,6 @@
+# This file is shared between document-updater and web, so that the server and client share
+# an identical track changes implementation. Do not edit it directly in web or document-updater,
+# instead edit it at https://github.com/sharelatex/ranges-tracker, where it has a suite of tests
 load = () ->
 	class RangesTracker
 		# The purpose of this class is to track a set of inserts and deletes to a document, like
@@ -78,6 +81,13 @@ load = () ->
 			@comments = @comments.filter (c) -> c.id != comment_id
 			@_markAsDirty comment, "comment", "removed"
 		
+		moveCommentId: (comment_id, position, text) ->
+			for comment in @comments
+				if comment.id == comment_id
+					comment.op.p = position
+					comment.op.c = text
+					@_markAsDirty comment, "comment", "moved"
+
 		getChange: (change_id) ->
 			change = null
 			for c in @changes
@@ -90,6 +100,18 @@ load = () ->
 			change = @getChange(change_id)
 			return if !change?
 			@_removeChange(change)
+		
+		validate: (text) ->
+			for change in @changes
+				if change.op.i?
+					content = text.slice(change.op.p, change.op.p + change.op.i.length)
+					if content != change.op.i
+						throw new Error("Change (#{JSON.stringify(change)}) doesn't match text (#{JSON.stringify(content)})")
+			for comment in @comments
+				content = text.slice(comment.op.p, comment.op.p + comment.op.c.length)
+				if content != comment.op.c
+					throw new Error("Comment (#{JSON.stringify(comment)}) doesn't match text (#{JSON.stringify(content)})")
+			return true
 
 		applyOp: (op, metadata = {}) ->
 			metadata.ts ?= new Date()
@@ -110,17 +132,21 @@ load = () ->
 				@applyOp(op, metadata)
 
 		addComment: (op, metadata) ->
-			# TODO: Don't allow overlapping comments?
-			@comments.push comment = {
-				id: op.t or @newId()
-				op: # Copy because we'll modify in place
-					c: op.c
-					p: op.p
-					t: op.t
-				metadata
-			}
-			@_markAsDirty comment, "comment", "added"
-			return comment
+			existing = @getComment(op.t)
+			if existing?
+				@moveCommentId(op.t, op.p, op.c)
+				return existing
+			else
+				@comments.push comment = {
+					id: op.t or @newId()
+					op: # Copy because we'll modify in place
+						c: op.c
+						p: op.p
+						t: op.t
+					metadata
+				}
+				@_markAsDirty comment, "comment", "added"
+				return comment
 		
 		applyInsertToComments: (op) ->
 			for comment in @comments