0.5.0-alpha.9

* Rewrite CSV conversion to dodge Serde

* Update CHANGELOG

.gitignore

@@ -2,4 +2,4 @@
 /target
 /scratch-project
 **/*.rs.bk
-/generate-docs.run
+/server/failed-snapshots/

.gitmodules

@@ -1,12 +1,6 @@
 [submodule "plugin/modules/roact"]
 	path = plugin/modules/roact
 	url = https://github.com/Roblox/roact.git
-[submodule "plugin/modules/rodux"]
-	path = plugin/modules/rodux
-	url = https://github.com/Roblox/rodux.git
-[submodule "plugin/modules/roact-rodux"]
-	path = plugin/modules/roact-rodux
-	url = https://github.com/Roblox/roact-rodux.git
 [submodule "plugin/modules/testez"]
 	path = plugin/modules/testez
 	url = https://github.com/Roblox/testez.git
@@ -16,3 +10,6 @@
 [submodule "plugin/modules/promise"]
 	path = plugin/modules/promise
 	url = https://github.com/LPGhatguy/roblox-lua-promise.git
+[submodule "plugin/modules/t"]
+	path = plugin/modules/t
+	url = https://github.com/osyrisrblx/t.git

.travis.yml

@@ -1,36 +1,41 @@
 matrix:
   include:
-    - language: python
-      env:
-        - LUA="lua=5.1"
+    # Lua tests are currently disabled because of holes in Lemur that are pretty
+    # tedious to fix. It should be fixed by either adding missing features to
+    # Lemur or by migrating to a CI system based on real Roblox instead.
 
-      before_install:
-        - pip install hererocks
-        - hererocks lua_install -r^ --$LUA
-        - export PATH=$PATH:$PWD/lua_install/bin
+    # - language: python
+    #   env:
+    #     - LUA="lua=5.1"
 
-      install:
-        - luarocks install luafilesystem
-        - luarocks install busted
-        - luarocks install luacov
-        - luarocks install luacov-coveralls
-        - luarocks install luacheck
+    #   before_install:
+    #     - pip install hererocks
+    #     - hererocks lua_install -r^ --$LUA
+    #     - export PATH=$PATH:$PWD/lua_install/bin
 
-      script:
-        - cd plugin
-        - luacheck src
-        - lua -lluacov spec.lua
+    #   install:
+    #     - luarocks install luafilesystem
+    #     - luarocks install busted
+    #     - luarocks install luacov
+    #     - luarocks install luacov-coveralls
+    #     - luarocks install luacheck
 
-      after_success:
-        - cd plugin
-        - luacov-coveralls -e $TRAVIS_BUILD_DIR/lua_install
+    #   script:
+    #     - cd plugin
+    #     - luacheck src
+    #     - lua -lluacov spec.lua
+
+    #   after_success:
+    #     - cd plugin
+    #     - luacov-coveralls -e $TRAVIS_BUILD_DIR/lua_install
 
     - language: rust
-      rust: 1.31.1
+      rust: 1.32.0
       cache: cargo
 
       script:
         - cargo test --verbose
+        - cargo test --verbose --all-features
 
     - language: rust
       rust: stable
@@ -38,10 +43,12 @@ matrix:
 
       script:
         - cargo test --verbose
+        - cargo test --verbose --all-features
 
     - language: rust
       rust: beta
       cache: cargo
 
       script:
-        - cargo test --verbose
+        - cargo test --verbose
+        - cargo test --verbose --all-features

CHANGELOG.md

@@ -2,6 +2,50 @@
 
 ## [Unreleased]
 
+## [0.5.0 Alpha 9](https://github.com/LPGhatguy/rojo/releases/tag/v0.5.0-alpha.9) (April 4, 2019)
+* Changed `rojo build` to use buffered I/O, which can make it up to 2x faster in some cases.
+    * Building [*Road Not Taken*](https://github.com/LPGhatguy/roads) to an `rbxlx` file dropped from 150ms to 70ms on my machine
+* Fixed `LocalizationTable` instances being made from `csv` files incorrectly interpreting empty rows and columns. ([#149](https://github.com/LPGhatguy/rojo/pull/149))
+* Fixed CSV files with entries that parse as numbers causing Rojo to panic. ([#152](https://github.com/LPGhatguy/rojo/pull/152))
+* Improved error messages when malformed CSV files are found in a Rojo project.
+
+## [0.5.0 Alpha 8](https://github.com/LPGhatguy/rojo/releases/tag/v0.5.0-alpha.8) (March 29, 2019)
+* Added support for a bunch of new types when dealing with XML model/place files:
+    * `ColorSequence`
+    * `Float64`
+    * `Int64`
+    * `NumberRange`
+    * `NumberSequence`
+    * `PhysicalProperties`
+    * `Ray`
+    * `Rect`
+    * `Ref`
+* Improved server instance ordering behavior when files are added during a live session ([#135](https://github.com/LPGhatguy/rojo/pull/135))
+* Fixed error being thrown when trying to unload the Rojo plugin.
+* Added partial fix for [issue #141](https://github.com/LPGhatguy/rojo/issues/141) for `Lighting.Technology`, which should restore live sync functionality for the default project file.
+
+## [0.5.0 Alpha 6](https://github.com/LPGhatguy/rojo/releases/tag/v0.5.0-alpha.6) (March 19, 2019)
+* Fixed `rojo init` giving unexpected results by upgrading to `rbx_dom_weak` 1.1.0
+* Fixed live server not responding when the Rojo plugin is connected ([#133](https://github.com/LPGhatguy/rojo/issues/133))
+* Updated default place file:
+    * Improved default properties to be closer to Studio's built-in 'Baseplate' template
+    * Added a baseplate to the project file (Thanks, [@AmaranthineCodices](https://github.com/AmaranthineCodices/)!)
+* Added more type support to Rojo plugin
+* Fixed some cases where the Rojo plugin would leave around objects that it knows should be deleted
+* Updated plugin to correctly listen to `Plugin.Unloading` when installing or uninstalling new plugins
+
+## [0.5.0 Alpha 5](https://github.com/LPGhatguy/rojo/releases/tag/v0.5.0-alpha.5) (March 1, 2019)
+* Upgraded core dependencies, which improves compatibility for lots of instance types
+    * Upgraded from `rbx_tree` 0.2.0 to `rbx_dom_weak` 1.0.0
+    * Upgraded from `rbx_xml` 0.2.0 to `rbx_xml` 0.4.0
+    * Upgraded from `rbx_binary` 0.2.0 to `rbx_binary` 0.4.0
+* Added support for non-primitive types in the Rojo plugin.
+    * Types like `Color3` and `CFrame` can now be updated live!
+* Fixed plugin assets flashing in on first load ([#121](https://github.com/LPGhatguy/rojo/issues/121))
+* Changed Rojo's HTTP server from Rouille to Hyper, which reduced the release size by around a megabyte.
+* Added property type inference to projects, which makes specifying services a lot easier ([#130](https://github.com/LPGhatguy/rojo/pull/130))
+* Made error messages from invalid and missing files more user-friendly
+
 ## [0.5.0 Alpha 4](https://github.com/LPGhatguy/rojo/releases/tag/v0.5.0-alpha.4) (February 8, 2019)
 * Added support for nested partitions ([#102](https://github.com/LPGhatguy/rojo/issues/102))
 * Added support for 'transmuting' partitions ([#112](https://github.com/LPGhatguy/rojo/issues/112))

README.md

@@ -62,7 +62,7 @@ If you use a plugin that _isn't_ Rojo for syncing code, open an issue and let me
 ## Contributing
 Pull requests are welcome!
 
-Rojo supports Rust 1.31.1 and newer. Any changes to the minimum required compiler version require a _minor_ version bump.
+Rojo supports Rust 1.32 and newer. Any changes to the minimum required compiler version require a _minor_ version bump.
 
 ## License
 Rojo is available under the terms of the Mozilla Public License, Version 2.0. See [LICENSE.txt](LICENSE.txt) for details.

docs/installation.md

@@ -25,7 +25,7 @@ If you have Rust installed, the easiest way to get Rojo is with Cargo!
 To install the latest 0.5.0 alpha, use:
 
 ```sh
-cargo install rojo --version 0.5.0-alpha.3
+cargo install rojo --version 0.5.0-alpha.9
 ```
 
 ## Installing the Plugin

plugin/.luacheckrc

@@ -13,6 +13,7 @@ stds.roblox = {
 
 		-- Types
 		"Vector2", "Vector3",
+		"Vector2int16", "Vector3int16",
 		"Color3",
 		"UDim", "UDim2",
 		"Rect",

plugin/default.project.json

@@ -8,14 +8,11 @@
     "Roact": {
       "$path": "modules/roact/lib"
     },
-    "Rodux": {
-      "$path": "modules/rodux/lib"
-    },
-    "RoactRodux": {
-      "$path": "modules/roact-rodux/lib"
-    },
     "Promise": {
       "$path": "modules/promise/lib"
+    },
+    "t": {
+      "$path": "modules/t/lib/t.lua"
     }
   }
 }

plugin/place.project.json

@@ -15,14 +15,11 @@
         "Roact": {
           "$path": "modules/roact/lib"
         },
-        "Rodux": {
-          "$path": "modules/rodux/lib"
-        },
-        "RoactRodux": {
-          "$path": "modules/roact-rodux/lib"
-        },
         "Promise": {
           "$path": "modules/promise/lib"
+        },
+        "t": {
+          "$path": "modules/t/lib/t.lua"
         }
       },
       "TestEZ": {
@@ -40,8 +37,8 @@
       }
     },
 
-    "TestService": {
-      "$className": "TestService",
+    "ServerScriptService": {
+      "$className": "ServerScriptService",
 
       "TestBootstrap": {
         "$path": "testBootstrap.server.lua"

plugin/src/Assets.lua

@@ -1,9 +1,7 @@
-local sheetAsset = "rbxassetid://2738712459"
-
 local Assets = {
 	Sprites = {
 		WhiteCross = {
-			asset = sheetAsset,
+			asset = "rbxassetid://2738712459",
 			offset = Vector2.new(190, 318),
 			size = Vector2.new(18, 18),
 		},

plugin/src/Components/App.lua

@@ -8,6 +8,7 @@ local Config = require(Plugin.Config)
 local Version = require(Plugin.Version)
 local Logging = require(Plugin.Logging)
 local DevSettings = require(Plugin.DevSettings)
+local preloadAssets = require(Plugin.preloadAssets)
 
 local ConnectPanel = require(Plugin.Components.ConnectPanel)
 local ConnectionActivePanel = require(Plugin.Components.ConnectionActivePanel)
@@ -177,6 +178,15 @@ function App:didMount()
 			})
 		end
 	end)
+
+	preloadAssets()
+end
+
+function App:willUnmount()
+	if self.currentSession ~= nil then
+		self.currentSession:disconnect()
+		self.currentSession = nil
+	end
 end
 
 function App:didUpdate()

plugin/src/Config.lua

@@ -1,6 +1,6 @@
 return {
 	codename = "Epiphany",
-	version = {0, 5, 0, "-alpha.4"},
+	version = {0, 5, 0, "-alpha.9"},
 	expectedServerVersionString = "0.5.0 or newer",
 	protocolVersion = 2,
 	defaultHost = "localhost",

plugin/src/DevSettings.lua

@@ -1,10 +1,27 @@
 local Config = require(script.Parent.Config)
 
+local Environment = {
+	User = "User",
+	Dev = "Dev",
+	Test = "Test",
+}
+
 local VALUES = {
 	LogLevel = {
 		type = "IntValue",
-		defaultUserValue = 2,
-		defaultDevValue = 3,
+		values = {
+			[Environment.User] = 2,
+			[Environment.Dev] = 3,
+			[Environment.Test] = 3,
+		},
+	},
+	TypecheckingEnabled = {
+		type = "BoolValue",
+		values = {
+			[Environment.User] = false,
+			[Environment.Dev] = true,
+			[Environment.Test] = true,
+		},
 	},
 }
 
@@ -42,7 +59,9 @@ local function setStoredValue(name, kind, value)
 	object.Value = value
 end
 
-local function createAllValues()
+local function createAllValues(environment)
+	assert(Environment[environment] ~= nil, "Invalid environment")
+
 	valueContainer = getValueContainer()
 
 	if valueContainer == nil then
@@ -52,20 +71,57 @@ local function createAllValues()
 	end
 
 	for name, value in pairs(VALUES) do
-		setStoredValue(name, value.type, value.defaultDevValue)
+		setStoredValue(name, value.type, value.values[environment])
 	end
 end
 
-_G[("ROJO_%s_DEV_CREATE"):format(Config.codename:upper())] = createAllValues
+local function getValue(name)
+	assert(VALUES[name] ~= nil, "Invalid DevSettings name")
+
+	local stored = getStoredValue(name)
+
+	if stored ~= nil then
+		return stored
+	end
+
+	return VALUES[name].values[Environment.User]
+end
 
 local DevSettings = {}
 
+function DevSettings:createDevSettings()
+	createAllValues(Environment.Dev)
+end
+
+function DevSettings:createTestSettings()
+	createAllValues(Environment.Test)
+end
+
+function DevSettings:hasChangedValues()
+	return valueContainer ~= nil
+end
+
+function DevSettings:resetValues()
+	if valueContainer then
+		valueContainer:Destroy()
+		valueContainer = nil
+	end
+end
+
 function DevSettings:isEnabled()
 	return valueContainer ~= nil
 end
 
 function DevSettings:getLogLevel()
-	return getStoredValue("LogLevel") or VALUES.LogLevel.defaultUserValue
+	return getValue("LogLevel")
+end
+
+function DevSettings:shouldTypecheck()
+	return getValue("TypecheckingEnabled")
+end
+
+function _G.ROJO_DEV_CREATE()
+	DevSettings:createDevSettings()
 end
 
 return DevSettings

plugin/src/InstanceMap.lua

@@ -0,0 +1,81 @@
+local Logging = require(script.Parent.Logging)
+
+--[[
+	A bidirectional map between instance IDs and Roblox instances. It lets us
+	keep track of every instance we know about.
+
+	TODO: Track ancestry to catch when stuff moves?
+]]
+local InstanceMap = {}
+InstanceMap.__index = InstanceMap
+
+function InstanceMap.new()
+	local self = {
+		fromIds = {},
+		fromInstances = {},
+	}
+
+	return setmetatable(self, InstanceMap)
+end
+
+function InstanceMap:insert(id, instance)
+	self.fromIds[id] = instance
+	self.fromInstances[instance] = id
+end
+
+function InstanceMap:removeId(id)
+	local instance = self.fromIds[id]
+
+	if instance ~= nil then
+		self.fromIds[id] = nil
+		self.fromInstances[instance] = nil
+	else
+		Logging.warn("Attempted to remove nonexistant ID %s", tostring(id))
+	end
+end
+
+function InstanceMap:removeInstance(instance)
+	local id = self.fromInstances[instance]
+
+	if id ~= nil then
+		self.fromInstances[instance] = nil
+		self.fromIds[id] = nil
+	else
+		Logging.warn("Attempted to remove nonexistant instance %s", tostring(instance))
+	end
+end
+
+function InstanceMap:destroyInstance(instance)
+	local id = self.fromInstances[instance]
+
+	if id ~= nil then
+		self:destroyId(id)
+	else
+		Logging.warn("Attempted to destroy untracked instance %s", tostring(instance))
+	end
+end
+
+function InstanceMap:destroyId(id)
+	local instance = self.fromIds[id]
+	self:removeId(id)
+
+	if instance ~= nil then
+		local descendantsToDestroy = {}
+
+		for otherInstance in pairs(self.fromInstances) do
+			if otherInstance:IsDescendantOf(instance) then
+				table.insert(descendantsToDestroy, otherInstance)
+			end
+		end
+
+		for _, otherInstance in ipairs(descendantsToDestroy) do
+			self:removeInstance(otherInstance)
+		end
+
+		instance:Destroy()
+	else
+		Logging.warn("Attempted to destroy nonexistant ID %s", tostring(id))
+	end
+end
+
+return InstanceMap

plugin/src/Reconciler.lua

@@ -1,108 +1,17 @@
+local t = require(script.Parent.Parent.t)
+
+local InstanceMap = require(script.Parent.InstanceMap)
 local Logging = require(script.Parent.Logging)
-
-local function makeInstanceMap()
-	local self = {
-		fromIds = {},
-		fromInstances = {},
-	}
-
-	function self:insert(id, instance)
-		self.fromIds[id] = instance
-		self.fromInstances[instance] = id
-	end
-
-	function self:removeId(id)
-		local instance = self.fromIds[id]
-
-		if instance ~= nil then
-			self.fromIds[id] = nil
-			self.fromInstances[instance] = nil
-		else
-			Logging.warn("Attempted to remove nonexistant ID %s", tostring(id))
-		end
-	end
-
-	function self:removeInstance(instance)
-		local id = self.fromInstances[instance]
-
-		if id ~= nil then
-			self.fromInstances[instance] = nil
-			self.fromIds[id] = nil
-		else
-			Logging.warn("Attempted to remove nonexistant instance %s", tostring(instance))
-		end
-	end
-
-	function self:destroyId(id)
-		local instance = self.fromIds[id]
-		self:removeId(id)
-
-		if instance ~= nil then
-			local descendantsToDestroy = {}
-
-			for otherInstance in pairs(self.fromInstances) do
-				if otherInstance:IsDescendantOf(instance) then
-					table.insert(descendantsToDestroy, otherInstance)
-				end
-			end
-
-			for _, otherInstance in ipairs(descendantsToDestroy) do
-				self:removeInstance(otherInstance)
-			end
-
-			instance:Destroy()
-		else
-			Logging.warn("Attempted to destroy nonexistant ID %s", tostring(id))
-		end
-	end
-
-	return self
-end
-
-local function setProperty(instance, key, value)
-	-- The 'Contents' property of LocalizationTable isn't directly exposed, but
-	-- has corresponding (deprecated) getters and setters.
-	if key == "Contents" and instance.ClassName == "LocalizationTable" then
-		instance:SetContents(value)
-		return
-	end
-
-	-- If we don't have permissions to access this value at all, we can skip it.
-	local readSuccess, existingValue = pcall(function()
-		return instance[key]
-	end)
-
-	if not readSuccess then
-		-- An error will be thrown if there was a permission issue or if the
-		-- property doesn't exist. In the latter case, we should tell the user
-		-- because it's probably their fault.
-		if existingValue:find("lacking permission") then
-			Logging.trace("Permission error reading property %s on class %s", tostring(key), instance.ClassName)
-			return
-		else
-			error(("Invalid property %s on class %s: %s"):format(tostring(key), instance.ClassName, existingValue), 2)
-		end
-	end
-
-	local writeSuccess, err = pcall(function()
-		if existingValue ~= value then
-			instance[key] = value
-		end
-	end)
-
-	if not writeSuccess then
-		error(("Cannot set property %s on class %s: %s"):format(tostring(key), instance.ClassName, err), 2)
-	end
-
-	return true
-end
+local setCanonicalProperty = require(script.Parent.setCanonicalProperty)
+local rojoValueToRobloxValue = require(script.Parent.rojoValueToRobloxValue)
+local Types = require(script.Parent.Types)
 
 local Reconciler = {}
 Reconciler.__index = Reconciler
 
 function Reconciler.new()
 	local self = {
-		instanceMap = makeInstanceMap(),
+		instanceMap = InstanceMap.new(),
 	}
 
 	return setmetatable(self, Reconciler)
@@ -118,11 +27,18 @@ function Reconciler:applyUpdate(requestedIds, virtualInstancesById)
 	end
 end
 
+local reconcileSchema = Types.ifEnabled(t.tuple(
+	t.map(t.string, Types.VirtualInstance),
+	t.string,
+	t.Instance
+))
 --[[
 	Update an existing instance, including its properties and children, to match
 	the given information.
 ]]
 function Reconciler:reconcile(virtualInstancesById, id, instance)
+	assert(reconcileSchema(virtualInstancesById, id, instance))
+
 	local virtualInstance = virtualInstancesById[id]
 
 	-- If an instance changes ClassName, we assume it's very different. That's
@@ -137,10 +53,10 @@ function Reconciler:reconcile(virtualInstancesById, id, instance)
 	self.instanceMap:insert(id, instance)
 
 	-- Some instances don't like being named, even if their name already matches
-	setProperty(instance, "Name", virtualInstance.Name)
+	setCanonicalProperty(instance, "Name", virtualInstance.Name)
 
 	for key, value in pairs(virtualInstance.Properties) do
-		setProperty(instance, key, value.Value)
+		setCanonicalProperty(instance, key, rojoValueToRobloxValue(value))
 	end
 
 	local existingChildren = instance:GetChildren()
@@ -175,10 +91,17 @@ function Reconciler:reconcile(virtualInstancesById, id, instance)
 		end
 	end
 
-	if self:__shouldClearUnknownInstances(virtualInstance) then
-		for existingChildInstance in pairs(unvisitedExistingChildren) do
-			self.instanceMap:removeInstance(existingChildInstance)
-			existingChildInstance:Destroy()
+	local shouldClearUnknown = self:__shouldClearUnknownChildren(virtualInstance)
+
+	for existingChildInstance in pairs(unvisitedExistingChildren) do
+		local childId = self.instanceMap.fromInstances[existingChildInstance]
+
+		if childId == nil then
+			if shouldClearUnknown then
+				existingChildInstance:Destroy()
+			end
+		else
+			self.instanceMap:destroyInstance(existingChildInstance)
 		end
 	end
 
@@ -194,16 +117,13 @@ function Reconciler:reconcile(virtualInstancesById, id, instance)
 
 		-- Some instances, like services, don't like having their Parent
 		-- property poked, even if we're setting it to the same value.
-		setProperty(instance, "Parent", parent)
-		if instance.Parent ~= parent then
-			instance.Parent = parent
-		end
+		setCanonicalProperty(instance, "Parent", parent)
 	end
 
 	return instance
 end
 
-function Reconciler:__shouldClearUnknownInstances(virtualInstance)
+function Reconciler:__shouldClearUnknownChildren(virtualInstance)
 	if virtualInstance.Metadata ~= nil then
 		return not virtualInstance.Metadata.ignoreUnknownInstances
 	else
@@ -211,29 +131,44 @@ function Reconciler:__shouldClearUnknownInstances(virtualInstance)
 	end
 end
 
+local reifySchema = Types.ifEnabled(t.tuple(
+	t.map(t.string, Types.VirtualInstance),
+	t.string,
+	t.Instance
+))
+
 function Reconciler:__reify(virtualInstancesById, id, parent)
+	assert(reifySchema(virtualInstancesById, id, parent))
+
 	local virtualInstance = virtualInstancesById[id]
 
 	local instance = Instance.new(virtualInstance.ClassName)
 
 	for key, value in pairs(virtualInstance.Properties) do
-		-- TODO: Branch on value.Type
-		setProperty(instance, key, value.Value)
+		setCanonicalProperty(instance, key, rojoValueToRobloxValue(value))
 	end
 
-	instance.Name = virtualInstance.Name
+	setCanonicalProperty(instance, "Name", virtualInstance.Name)
 
 	for _, childId in ipairs(virtualInstance.Children) do
 		self:__reify(virtualInstancesById, childId, instance)
 	end
 
-	setProperty(instance, "Parent", parent)
+	setCanonicalProperty(instance, "Parent", parent)
 	self.instanceMap:insert(id, instance)
 
 	return instance
 end
 
+local applyUpdatePieceSchema = Types.ifEnabled(t.tuple(
+	t.string,
+	t.map(t.string, t.boolean),
+	t.map(t.string, Types.VirtualInstance)
+))
+
 function Reconciler:__applyUpdatePiece(id, visitedIds, virtualInstancesById)
+	assert(applyUpdatePieceSchema(id, visitedIds, virtualInstancesById))
+
 	if visitedIds[id] then
 		return
 	end

plugin/src/Reconciler.spec.lua

@@ -0,0 +1,218 @@
+local Reconciler = require(script.Parent.Reconciler)
+
+return function()
+	it("should leave instances alone if there's nothing specified", function()
+		local instance = Instance.new("Folder")
+		instance.Name = "TestFolder"
+
+		local instanceId = "test-id"
+		local virtualInstancesById = {
+			[instanceId] = {
+				Name = "TestFolder",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+			},
+		}
+
+		local reconciler = Reconciler.new()
+		reconciler:reconcile(virtualInstancesById, instanceId, instance)
+	end)
+
+	it("should assign names from virtual instances", function()
+		local instance = Instance.new("Folder")
+		instance.Name = "InitialName"
+
+		local instanceId = "test-id"
+		local virtualInstancesById = {
+			[instanceId] = {
+				Name = "NewName",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+			},
+		}
+
+		local reconciler = Reconciler.new()
+		reconciler:reconcile(virtualInstancesById, instanceId, instance)
+
+		expect(instance.Name).to.equal("NewName")
+	end)
+
+	it("should assign properties from virtual instances", function()
+		local instance = Instance.new("IntValue")
+		instance.Name = "TestValue"
+		instance.Value = 5
+
+		local instanceId = "test-id"
+		local virtualInstancesById = {
+			[instanceId] = {
+				Name = "TestValue",
+				ClassName = "IntValue",
+				Children = {},
+				Properties = {
+					Value = {
+						Type = "Int32",
+						Value = 9
+					}
+				},
+			},
+		}
+
+		local reconciler = Reconciler.new()
+		reconciler:reconcile(virtualInstancesById, instanceId, instance)
+
+		expect(instance.Value).to.equal(9)
+	end)
+
+	it("should wipe unknown children by default", function()
+		local parent = Instance.new("Folder")
+		parent.Name = "Parent"
+
+		local child = Instance.new("Folder")
+		child.Name = "Child"
+
+		local parentId = "test-id"
+		local virtualInstancesById = {
+			[parentId] = {
+				Name = "Parent",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+			},
+		}
+
+		local reconciler = Reconciler.new()
+		reconciler:reconcile(virtualInstancesById, parentId, parent)
+
+		expect(#parent:GetChildren()).to.equal(0)
+	end)
+
+	it("should preserve unknown children if ignoreUnknownInstances is set", function()
+		local parent = Instance.new("Folder")
+		parent.Name = "Parent"
+
+		local child = Instance.new("Folder")
+		child.Parent = parent
+		child.Name = "Child"
+
+		local parentId = "test-id"
+		local virtualInstancesById = {
+			[parentId] = {
+				Name = "Parent",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+				Metadata = {
+					ignoreUnknownInstances = true,
+				},
+			},
+		}
+
+		local reconciler = Reconciler.new()
+		reconciler:reconcile(virtualInstancesById, parentId, parent)
+
+		expect(child.Parent).to.equal(parent)
+		expect(#parent:GetChildren()).to.equal(1)
+	end)
+
+	it("should remove known removed children", function()
+		local parent = Instance.new("Folder")
+		parent.Name = "Parent"
+
+		local child = Instance.new("Folder")
+		child.Parent = parent
+		child.Name = "Child"
+
+		local parentId = "parent-id"
+		local childId = "child-id"
+
+		local reconciler = Reconciler.new()
+
+		local virtualInstancesById = {
+			[parentId] = {
+				Name = "Parent",
+				ClassName = "Folder",
+				Children = {childId},
+				Properties = {},
+			},
+			[childId] = {
+				Name = "Child",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+			},
+		}
+		reconciler:reconcile(virtualInstancesById, parentId, parent)
+
+		expect(child.Parent).to.equal(parent)
+		expect(#parent:GetChildren()).to.equal(1)
+
+		local newVirtualInstances = {
+			[parentId] = {
+				Name = "Parent",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+			},
+			[childId] = nil,
+		}
+		reconciler:reconcile(newVirtualInstances, parentId, parent)
+
+		expect(child.Parent).to.equal(nil)
+		expect(#parent:GetChildren()).to.equal(0)
+	end)
+
+	it("should remove known removed children if ignoreUnknownInstances is set", function()
+		local parent = Instance.new("Folder")
+		parent.Name = "Parent"
+
+		local child = Instance.new("Folder")
+		child.Parent = parent
+		child.Name = "Child"
+
+		local parentId = "parent-id"
+		local childId = "child-id"
+
+		local reconciler = Reconciler.new()
+
+		local virtualInstancesById = {
+			[parentId] = {
+				Name = "Parent",
+				ClassName = "Folder",
+				Children = {childId},
+				Properties = {},
+				Metadata = {
+					ignoreUnknownInstances = true,
+				},
+			},
+			[childId] = {
+				Name = "Child",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+			},
+		}
+		reconciler:reconcile(virtualInstancesById, parentId, parent)
+
+		expect(child.Parent).to.equal(parent)
+		expect(#parent:GetChildren()).to.equal(1)
+
+		local newVirtualInstances = {
+			[parentId] = {
+				Name = "Parent",
+				ClassName = "Folder",
+				Children = {},
+				Properties = {},
+				Metadata = {
+					ignoreUnknownInstances = true,
+				},
+			},
+			[childId] = nil,
+		}
+		reconciler:reconcile(newVirtualInstances, parentId, parent)
+
+		expect(child.Parent).to.equal(nil)
+		expect(#parent:GetChildren()).to.equal(0)
+	end)
+end

plugin/src/Types.lua

@@ -0,0 +1,36 @@
+local t = require(script.Parent.Parent.t)
+
+local DevSettings = require(script.Parent.DevSettings)
+
+local VirtualValue = t.interface({
+	Type = t.string,
+	Value = t.optional(t.any),
+})
+
+local VirtualMetadata = t.interface({
+	ignoreUnknownInstances = t.optional(t.boolean),
+})
+
+local VirtualInstance = t.interface({
+	Name = t.string,
+	ClassName = t.string,
+	Properties = t.map(t.string, VirtualValue),
+	Metadata = t.optional(VirtualMetadata)
+})
+
+local function ifEnabled(innerCheck)
+	return function(...)
+		if DevSettings:shouldTypecheck() then
+			return innerCheck(...)
+		else
+			return true
+		end
+	end
+end
+
+return {
+	ifEnabled = ifEnabled,
+	VirtualInstance = VirtualInstance,
+	VirtualMetadata = VirtualMetadata,
+	VirtualValue = VirtualValue,
+}

plugin/src/init.server.lua

@@ -4,16 +4,14 @@ end
 
 local Roact = require(script.Parent.Roact)
 
-Roact.setGlobalConfig({
-	elementTracing = true,
-})
-
 local App = require(script.Components.App)
 
 local app = Roact.createElement(App, {
 	plugin = plugin,
 })
 
-Roact.mount(app, game:GetService("CoreGui"), "Rojo UI")
+local tree = Roact.mount(app, game:GetService("CoreGui"), "Rojo UI")
 
--- TODO: Detect another instance of Rojo coming online and shut down this one.
+plugin.Unloading:Connect(function()
+	Roact.unmount(tree)
+end)

plugin/src/preloadAssets.lua

@@ -0,0 +1,28 @@
+local ContentProvider = game:GetService("ContentProvider")
+
+local Logging = require(script.Parent.Logging)
+local Assets = require(script.Parent.Assets)
+
+local function preloadAssets()
+	local contentUrls = {}
+
+	for _, sprite in pairs(Assets.Sprites) do
+		table.insert(contentUrls, sprite.asset)
+	end
+
+	for _, slice in pairs(Assets.Slices) do
+		table.insert(contentUrls, slice.asset)
+	end
+
+	for _, url in pairs(Assets.Images) do
+		table.insert(contentUrls, url)
+	end
+
+	Logging.trace("Preloading assets: %s", table.concat(contentUrls, ", "))
+
+	coroutine.wrap(function()
+		ContentProvider:PreloadAsync(contentUrls)
+	end)()
+end
+
+return preloadAssets

plugin/src/rojoValueToRobloxValue.lua

@@ -0,0 +1,38 @@
+local primitiveTypes = {
+	Bool = true,
+	Enum = true,
+	Float32 = true,
+	Float64 = true,
+	Int32 = true,
+	Int64 = true,
+	String = true,
+}
+
+local directConstructors = {
+	CFrame = CFrame.new,
+	Color3 = Color3.new,
+	Color3uint8 = Color3.fromRGB,
+	Rect = Rect.new,
+	UDim = UDim.new,
+	UDim2 = UDim2.new,
+	Vector2 = Vector2.new,
+	Vector2int16 = Vector2int16.new,
+	Vector3 = Vector3.new,
+	Vector3int16 = Vector3int16.new,
+}
+
+local function rojoValueToRobloxValue(value)
+	if primitiveTypes[value.Type] then
+		return value.Value
+	end
+
+	local constructor = directConstructors[value.Type]
+	if constructor ~= nil then
+		return constructor(unpack(value.Value))
+	end
+
+	local errorMessage = ("The Rojo plugin doesn't know how to handle values of type %q yet!"):format(tostring(value.Type))
+	error(errorMessage)
+end
+
+return rojoValueToRobloxValue

plugin/src/rojoValueToRobloxValue.spec.lua

@@ -0,0 +1,40 @@
+local rojoValueToRobloxValue = require(script.Parent.rojoValueToRobloxValue)
+
+return function()
+	it("should convert primitives", function()
+		local inputString = {
+			Type = "String",
+			Value = "Hello, world!",
+		}
+
+		local inputFloat32 = {
+			Type = "Float32",
+			Value = 12341.512,
+		}
+
+		expect(rojoValueToRobloxValue(inputString)).to.equal(inputString.Value)
+		expect(rojoValueToRobloxValue(inputFloat32)).to.equal(inputFloat32.Value)
+	end)
+
+	it("should convert properties with direct constructors", function()
+		local inputColor3 = {
+			Type = "Color3",
+			Value = {0, 1, 0.5},
+		}
+		local outputColor3 = Color3.new(0, 1, 0.5)
+
+		local inputCFrame = {
+			Type = "CFrame",
+			Value = {
+				1, 2, 3,
+				4, 5, 6,
+				7, 8, 9,
+				10, 11, 12,
+			},
+		}
+		local outputCFrame = CFrame.new(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
+
+		expect(rojoValueToRobloxValue(inputColor3)).to.equal(outputColor3)
+		expect(rojoValueToRobloxValue(inputCFrame)).to.equal(outputCFrame)
+	end)
+end

plugin/src/setCanonicalProperty.lua

@@ -0,0 +1,57 @@
+local Logging = require(script.Parent.Logging)
+
+--[[
+	Attempts to set a property on the given instance.
+
+	This method deals in terms of what Rojo calls 'canonical properties', which
+	don't necessarily exist either in serialization or in Lua-reflected APIs,
+	but may be present in the API dump.
+
+	Ideally, canonical properties map 1:1 with properties we can assign, but in
+	some cases like LocalizationTable contents and CollectionService tags, we
+	have to read/write properties a little differently.
+]]
+local function setCanonicalProperty(instance, key, value)
+	-- The 'Contents' property of LocalizationTable isn't directly exposed, but
+	-- has corresponding (deprecated) getters and setters.
+	if instance.ClassName == "LocalizationTable" and key == "Contents" then
+		instance:SetContents(value)
+		return
+	end
+
+	-- Temporary workaround for fixing issue #141 in this specific case.
+	if instance.ClassName == "Lighting" and key == "Technology" then
+		return
+	end
+
+	-- If we don't have permissions to access this value at all, we can skip it.
+	local readSuccess, existingValue = pcall(function()
+		return instance[key]
+	end)
+
+	if not readSuccess then
+		-- An error will be thrown if there was a permission issue or if the
+		-- property doesn't exist. In the latter case, we should tell the user
+		-- because it's probably their fault.
+		if existingValue:find("lacking permission") then
+			Logging.trace("Permission error reading property %s on class %s", tostring(key), instance.ClassName)
+			return
+		else
+			error(("Invalid property %s on class %s: %s"):format(tostring(key), instance.ClassName, existingValue), 2)
+		end
+	end
+
+	local writeSuccess, err = pcall(function()
+		if existingValue ~= value then
+			instance[key] = value
+		end
+	end)
+
+	if not writeSuccess then
+		error(("Cannot set property %s on class %s: %s"):format(tostring(key), instance.ClassName, err), 2)
+	end
+
+	return true
+end
+
+return setCanonicalProperty

plugin/testBootstrap.server.lua

@@ -1,2 +1,19 @@
-local TestEZ = require(game.ReplicatedStorage.TestEZ)
-TestEZ.TestBootstrap:run(game.ReplicatedStorage.Rojo.plugin)
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+local TestEZ = require(ReplicatedStorage.TestEZ)
+
+local Rojo = ReplicatedStorage.Rojo
+
+local DevSettings = require(Rojo.Plugin.DevSettings)
+
+local setDevSettings = not DevSettings:hasChangedValues()
+
+if setDevSettings then
+	DevSettings:createTestSettings()
+end
+
+TestEZ.TestBootstrap:run({Rojo.Plugin})
+
+if setDevSettings then
+	DevSettings:resetValues()
+end

server/Cargo.toml

@@ -1,12 +1,16 @@
 [package]
 name = "rojo"
-version = "0.5.0-alpha.4"
+version = "0.5.0-alpha.9"
 authors = ["Lucien Greathouse <me@lpghatguy.com>"]
 description = "A tool to create robust Roblox projects"
 license = "MIT"
 repository = "https://github.com/LPGhatguy/rojo"
 edition = "2018"
 
+[features]
+default = []
+server-plugins = []
+
 [lib]
 name = "librojo"
 path = "src/lib.rs"
@@ -15,25 +19,24 @@ path = "src/lib.rs"
 name = "rojo"
 path = "src/bin.rs"
 
-[features]
-default = []
-bundle-plugin = []
-
 [dependencies]
 clap = "2.27"
 csv = "1.0"
 env_logger = "0.6"
 failure = "0.1.3"
+futures = "0.1"
+hyper = "0.12"
 log = "0.4"
 maplit = "1.0.1"
 notify = "4.0"
-rand = "0.4"
-rbx_binary = "0.2.0"
-rbx_tree = "0.2.0"
-rbx_xml = "0.2.0"
+rbx_binary = "0.4.0"
+rbx_dom_weak = "1.3.0"
+rbx_xml = "0.6.0"
+rbx_reflection = "2.0.374"
 regex = "1.0"
 reqwest = "0.9.5"
-rouille = "2.1"
+rlua = "0.16"
+ritz = "0.1.0"
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
@@ -43,5 +46,5 @@ uuid = { version = "0.7", features = ["v4", "serde"] }
 tempfile = "3.0"
 walkdir = "2.1"
 lazy_static = "1.2"
-pretty_assertions = "0.5.1"
+pretty_assertions = "0.6.1"
 paste = "0.1"

server/assets/index.css

@@ -0,0 +1,43 @@
+* {
+  margin: 0;
+  padding: 0;
+  font: inherit;
+}
+
+html {
+  font-family: sans-serif;
+  height: 100%;
+}
+
+body {
+  height: 100%;
+  display: flex;
+  flex-direction: column;
+  justify-content: center;
+}
+
+.main {
+  padding: 1rem;
+  text-align: center;
+  margin: 0 auto;
+  width: 100%;
+  max-width: 60rem;
+  background-color: #efefef;
+  border: 1px solid #666;
+  border-radius: 4px;
+}
+
+.title {
+  font-size: 2rem;
+  font-weight: bold;
+}
+
+.subtitle {
+  font-size: 1.5rem;
+  font-weight: bold;
+}
+
+.docs {
+  font-size: 1.3rem;
+  font-weight: bold;
+}

server/assets/index.html

@@ -1,54 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-	<title>Rojo</title>
-	<style>
-		* {
-			margin: 0;
-			padding: 0;
-			font: inherit;
-		}
-
-		html {
-			font-family: sans-serif;
-			height: 100%;
-		}
-
-		body {
-			height: 100%;
-			display: flex;
-			flex-direction: column;
-			justify-content: center;
-		}
-
-		.main {
-			padding: 1rem;
-			text-align: center;
-			margin: 0 auto;
-			width: 100%;
-			max-width: 60rem;
-			background-color: #efefef;
-			border: 1px solid #666;
-			border-radius: 4px;
-		}
-
-		.title {
-			font-size: 2rem;
-			font-weight: bold;
-		}
-
-		.docs {
-			font-size: 1.5rem;
-			font-weight: bold;
-		}
-	</style>
-</head>
-<body>
-
-<div class="main">
-	<h1 class="title">Rojo Live Sync is up and running!</h1>
-	<a class="docs" href="https://lpghatguy.github.io/rojo">Rojo Documentation</a>
-</div>
-
-</body>
-</html>

server/assets/place.project.json

@@ -0,0 +1,66 @@
+{
+  "name": "[placeholder]",
+  "tree": {
+    "$className": "DataModel",
+    "HttpService": {
+      "$className": "HttpService",
+      "$properties": {
+        "HttpEnabled": true
+      }
+    },
+    "Lighting": {
+      "$className": "Lighting",
+      "$properties": {
+        "Ambient": [
+          0,
+          0,
+          0
+        ],
+        "Brightness": 2,
+        "GlobalShadows": true,
+        "Outlines": false,
+        "Technology": "Voxel"
+      }
+    },
+    "ReplicatedStorage": {
+      "$className": "ReplicatedStorage",
+      "Source": {
+        "$path": "src"
+      }
+    },
+    "SoundService": {
+      "$className": "SoundService",
+      "$properties": {
+        "RespectFilteringEnabled": true
+      }
+    },
+    "Workspace": {
+      "$className": "Workspace",
+      "$properties": {
+        "FilteringEnabled": true
+      },
+      "Baseplate": {
+        "$className": "Part",
+        "$properties": {
+          "Anchored": true,
+          "Color": [
+            0.38823,
+            0.37254,
+            0.38823
+          ],
+          "Locked": true,
+          "Position": [
+            0,
+            -10,
+            0
+          ],
+          "Size": [
+            512,
+            20,
+            512
+          ]
+        }
+      }
+    }
+  }
+}

server/src/commands/build.rs

@@ -1,16 +1,17 @@
 use std::{
     path::PathBuf,
     fs::File,
-    io,
+    io::{self, Write, BufWriter},
 };
 
 use log::info;
 use failure::Fail;
 
 use crate::{
-    rbx_session::construct_oneoff_tree,
-    project::{Project, ProjectLoadFuzzyError},
     imfs::{Imfs, FsError},
+    project::{Project, ProjectLoadFuzzyError},
+    rbx_session::construct_oneoff_tree,
+    rbx_snapshot::SnapshotError,
 };
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -59,6 +60,9 @@ pub enum BuildError {
 
     #[fail(display = "{}", _0)]
     FsError(#[fail(cause)] FsError),
+
+    #[fail(display = "{}", _0)]
+    SnapshotError(#[fail(cause)] SnapshotError),
 }
 
 impl_from!(BuildError {
@@ -67,6 +71,7 @@ impl_from!(BuildError {
     rbx_xml::EncodeError => XmlModelEncodeError,
     rbx_binary::EncodeError => BinaryModelEncodeError,
     FsError => FsError,
+    SnapshotError => SnapshotError,
 });
 
 pub fn build(options: &BuildOptions) -> Result<(), BuildError> {
@@ -86,8 +91,8 @@ pub fn build(options: &BuildOptions) -> Result<(), BuildError> {
 
     let mut imfs = Imfs::new();
     imfs.add_roots_from_project(&project)?;
-    let tree = construct_oneoff_tree(&project, &imfs);
-    let mut file = File::create(&options.output_file)?;
+    let tree = construct_oneoff_tree(&project, &imfs)?;
+    let mut file = BufWriter::new(File::create(&options.output_file)?);
 
     match output_kind {
         OutputKind::Rbxmx => {
@@ -116,5 +121,7 @@ pub fn build(options: &BuildOptions) -> Result<(), BuildError> {
         },
     }
 
+    file.flush()?;
+
     Ok(())
 }

server/src/commands/serve.rs

@@ -8,9 +8,9 @@ use failure::Fail;
 
 use crate::{
     project::{Project, ProjectLoadFuzzyError},
-    web::Server,
+    web::LiveServer,
     imfs::FsError,
-    live_session::LiveSession,
+    live_session::{LiveSession, LiveSessionError},
 };
 
 const DEFAULT_PORT: u16 = 34872;
@@ -28,11 +28,15 @@ pub enum ServeError {
 
    #[fail(display = "{}", _0)]
    FsError(#[fail(cause)] FsError),
+
+   #[fail(display = "{}", _0)]
+   LiveSessionError(#[fail(cause)] LiveSessionError),
 }
 
 impl_from!(ServeError {
     ProjectLoadFuzzyError => ProjectLoadError,
     FsError => FsError,
+    LiveSessionError => LiveSessionError,
 });
 
 pub fn serve(options: &ServeOptions) -> Result<(), ServeError> {
@@ -45,7 +49,7 @@ pub fn serve(options: &ServeOptions) -> Result<(), ServeError> {
     info!("Using project {:#?}", project);
 
     let live_session = Arc::new(LiveSession::new(Arc::clone(&project))?);
-    let server = Server::new(Arc::clone(&live_session));
+    let server = LiveServer::new(live_session);
 
     let port = options.port
         .or(project.serve_port)
@@ -53,7 +57,7 @@ pub fn serve(options: &ServeOptions) -> Result<(), ServeError> {
 
     println!("Rojo server listening on port {}", port);
 
-    server.listen(port);
+    server.start(port);
 
     Ok(())
 }

server/src/commands/upload.rs

@@ -9,9 +9,10 @@ use failure::Fail;
 use reqwest::header::{ACCEPT, USER_AGENT, CONTENT_TYPE, COOKIE};
 
 use crate::{
-    rbx_session::construct_oneoff_tree,
-    project::{Project, ProjectLoadFuzzyError},
     imfs::{Imfs, FsError},
+    project::{Project, ProjectLoadFuzzyError},
+    rbx_session::construct_oneoff_tree,
+    rbx_snapshot::SnapshotError,
 };
 
 #[derive(Debug, Fail)]
@@ -36,6 +37,9 @@ pub enum UploadError {
 
     #[fail(display = "{}", _0)]
     FsError(#[fail(cause)] FsError),
+
+    #[fail(display = "{}", _0)]
+    SnapshotError(#[fail(cause)] SnapshotError),
 }
 
 impl_from!(UploadError {
@@ -44,6 +48,7 @@ impl_from!(UploadError {
     reqwest::Error => HttpError,
     rbx_xml::EncodeError => XmlModelEncodeError,
     FsError => FsError,
+    SnapshotError => SnapshotError,
 });
 
 #[derive(Debug)]
@@ -67,7 +72,7 @@ pub fn upload(options: &UploadOptions) -> Result<(), UploadError> {
 
     let mut imfs = Imfs::new();
     imfs.add_roots_from_project(&project)?;
-    let tree = construct_oneoff_tree(&project, &imfs);
+    let tree = construct_oneoff_tree(&project, &imfs)?;
 
     let root_id = tree.get_root_id();
     let mut contents = Vec::new();

server/src/imfs.rs

@@ -1,9 +1,10 @@
 use std::{
-    collections::{HashMap, HashSet},
-    path::{self, Path, PathBuf},
+    cmp::Ordering,
+    collections::{HashMap, HashSet, BTreeSet},
     fmt,
     fs,
     io,
+    path::{self, Path, PathBuf},
 };
 
 use failure::Fail;
@@ -237,7 +238,7 @@ impl Imfs {
         } else if metadata.is_dir() {
             let item = ImfsItem::Directory(ImfsDirectory {
                 path: path.to_path_buf(),
-                children: HashSet::new(),
+                children: BTreeSet::new(),
             });
 
             self.items.insert(path.to_path_buf(), item);
@@ -285,19 +286,43 @@ impl Imfs {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct ImfsFile {
     pub path: PathBuf,
     pub contents: Vec<u8>,
 }
 
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct ImfsDirectory {
-    pub path: PathBuf,
-    pub children: HashSet<PathBuf>,
+impl PartialOrd for ImfsFile {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
 }
 
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+impl Ord for ImfsFile {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.path.cmp(&other.path)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct ImfsDirectory {
+    pub path: PathBuf,
+    pub children: BTreeSet<PathBuf>,
+}
+
+impl PartialOrd for ImfsDirectory {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for ImfsDirectory {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.path.cmp(&other.path)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Serialize, Deserialize)]
 pub enum ImfsItem {
     File(ImfsFile),
     Directory(ImfsDirectory),

server/src/lib.rs

@@ -1,3 +1,5 @@
+#![recursion_limit="128"]
+
 // Macros
 #[macro_use]
 pub mod impl_from;
@@ -16,5 +18,4 @@ pub mod rbx_snapshot;
 pub mod session_id;
 pub mod snapshot_reconciler;
 pub mod visualize;
-pub mod web;
-pub mod web_util;
+pub mod web;

server/src/live_session.rs

@@ -1,21 +1,40 @@
 use std::{
+    collections::HashSet,
+    mem,
     sync::{Arc, Mutex},
 };
 
+use failure::Fail;
+
 use crate::{
     fs_watcher::FsWatcher,
     imfs::{Imfs, FsError},
     message_queue::MessageQueue,
     project::Project,
     rbx_session::RbxSession,
+    rbx_snapshot::SnapshotError,
     session_id::SessionId,
     snapshot_reconciler::InstanceChanges,
 };
 
+#[derive(Debug, Fail)]
+pub enum LiveSessionError {
+    #[fail(display = "{}", _0)]
+    Fs(#[fail(cause)] FsError),
+
+    #[fail(display = "{}", _0)]
+    Snapshot(#[fail(cause)] SnapshotError),
+}
+
+impl_from!(LiveSessionError {
+    FsError => Fs,
+    SnapshotError => Snapshot,
+});
+
 /// Contains all of the state for a Rojo live-sync session.
 pub struct LiveSession {
-    pub project: Arc<Project>,
-    pub session_id: SessionId,
+    project: Arc<Project>,
+    session_id: SessionId,
     pub message_queue: Arc<MessageQueue<InstanceChanges>>,
     pub rbx_session: Arc<Mutex<RbxSession>>,
     pub imfs: Arc<Mutex<Imfs>>,
@@ -23,7 +42,7 @@ pub struct LiveSession {
 }
 
 impl LiveSession {
-    pub fn new(project: Arc<Project>) -> Result<LiveSession, FsError> {
+    pub fn new(project: Arc<Project>) -> Result<LiveSession, LiveSessionError> {
         let imfs = {
             let mut imfs = Imfs::new();
             imfs.add_roots_from_project(&project)?;
@@ -36,7 +55,7 @@ impl LiveSession {
             Arc::clone(&project),
             Arc::clone(&imfs),
             Arc::clone(&message_queue),
-        )));
+        )?));
 
         let fs_watcher = FsWatcher::start(
             Arc::clone(&imfs),
@@ -46,8 +65,8 @@ impl LiveSession {
         let session_id = SessionId::new();
 
         Ok(LiveSession {
-            project,
             session_id,
+            project,
             message_queue,
             rbx_session,
             imfs,
@@ -55,7 +74,26 @@ impl LiveSession {
         })
     }
 
-    pub fn get_project(&self) -> &Project {
+    /// Restarts the live session using the given project while preserving the
+    /// internal session ID.
+    pub fn restart_with_new_project(&mut self, project: Arc<Project>) -> Result<(), LiveSessionError> {
+        let mut new_session = LiveSession::new(project)?;
+        new_session.session_id = self.session_id;
+
+        mem::replace(self, new_session);
+
+        Ok(())
+    }
+
+    pub fn root_project(&self) -> &Project {
         &self.project
     }
+
+    pub fn session_id(&self) -> SessionId {
+        self.session_id
+    }
+
+    pub fn serve_place_ids(&self) -> &Option<HashSet<u64>> {
+        &self.project.serve_place_ids
+    }
 }

server/src/message_queue.rs

@@ -1,67 +1,83 @@
 use std::{
-    collections::HashMap,
+    mem,
     sync::{
-        mpsc,
-        atomic::{AtomicUsize, Ordering},
         RwLock,
         Mutex,
     },
 };
 
-/// A unique identifier, not guaranteed to be generated in any order.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct ListenerId(usize);
+use futures::sync::oneshot;
 
-/// Generate a new ID, which has no defined ordering.
-pub fn get_listener_id() -> ListenerId {
-    static LAST_ID: AtomicUsize = AtomicUsize::new(0);
+struct Listener<T> {
+    sender: oneshot::Sender<(u32, Vec<T>)>,
+    cursor: u32,
+}
 
-    ListenerId(LAST_ID.fetch_add(1, Ordering::SeqCst))
+fn fire_listener_if_ready<T: Clone>(messages: &[T], listener: Listener<T>) -> Result<(), Listener<T>> {
+    let current_cursor = messages.len() as u32;
+
+    if listener.cursor < current_cursor {
+        let new_messages = messages[(listener.cursor as usize)..].to_vec();
+        let _ = listener.sender.send((current_cursor, new_messages));
+        Ok(())
+    } else {
+        Err(listener)
+    }
 }
 
 /// A message queue with persistent history that can be subscribed to.
 ///
-/// Definitely non-optimal, but a simple design that works well for the
-/// synchronous web server Rojo uses, Rouille.
+/// Definitely non-optimal. This would ideally be a lockless mpmc queue.
 #[derive(Default)]
 pub struct MessageQueue<T> {
    messages: RwLock<Vec<T>>,
-   message_listeners: Mutex<HashMap<ListenerId, mpsc::Sender<()>>>,
+   message_listeners: Mutex<Vec<Listener<T>>>,
 }
 
 impl<T: Clone> MessageQueue<T> {
     pub fn new() -> MessageQueue<T> {
         MessageQueue {
             messages: RwLock::new(Vec::new()),
-            message_listeners: Mutex::new(HashMap::new()),
+            message_listeners: Mutex::new(Vec::new()),
         }
     }
 
     pub fn push_messages(&self, new_messages: &[T]) {
-        let message_listeners = self.message_listeners.lock().unwrap();
+        let mut message_listeners = self.message_listeners.lock().unwrap();
+        let mut messages = self.messages.write().unwrap();
+        messages.extend_from_slice(new_messages);
 
-        {
-            let mut messages = self.messages.write().unwrap();
-            messages.extend_from_slice(new_messages);
+        let mut remaining_listeners = Vec::new();
+
+        for listener in message_listeners.drain(..) {
+            match fire_listener_if_ready(&messages, listener) {
+                Ok(_) => {}
+                Err(listener) => remaining_listeners.push(listener)
+            }
         }
 
-        for listener in message_listeners.values() {
-            listener.send(()).unwrap();
-        }
+        // Without this annotation, Rust gets confused since the first argument
+        // is a MutexGuard, but the second is a Vec.
+        mem::replace::<Vec<_>>(&mut message_listeners, remaining_listeners);
     }
 
-    pub fn subscribe(&self, sender: mpsc::Sender<()>) -> ListenerId {
-        let id = get_listener_id();
+    pub fn subscribe(&self, cursor: u32, sender: oneshot::Sender<(u32, Vec<T>)>) {
+        let listener = {
+            let listener = Listener {
+                sender,
+                cursor,
+            };
+
+            let messages = self.messages.read().unwrap();
+
+            match fire_listener_if_ready(&messages, listener) {
+                Ok(_) => return,
+                Err(listener) => listener
+            }
+        };
 
         let mut message_listeners = self.message_listeners.lock().unwrap();
-        message_listeners.insert(id, sender);
-
-        id
-    }
-
-    pub fn unsubscribe(&self, id: ListenerId) {
-        let mut message_listeners = self.message_listeners.lock().unwrap();
-        message_listeners.remove(&id);
+        message_listeners.push(listener);
     }
 
     pub fn get_message_cursor(&self) -> u32 {

server/src/path_map.rs

@@ -20,6 +20,12 @@ pub struct PathMap<T> {
     nodes: HashMap<PathBuf, PathMapNode<T>>,
 }
 
+impl<T> Default for PathMap<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl<T> PathMap<T> {
     pub fn new() -> PathMap<T> {
         PathMap {

server/src/project.rs

@@ -1,5 +1,5 @@
 use std::{
-    collections::{HashMap, HashSet},
+    collections::{HashMap, HashSet, BTreeMap},
     fmt,
     fs::{self, File},
     io,
@@ -8,9 +8,11 @@ use std::{
 
 use log::warn;
 use failure::Fail;
-use maplit::hashmap;
-use rbx_tree::RbxValue;
+use rbx_dom_weak::{UnresolvedRbxValue, RbxValue};
 use serde_derive::{Serialize, Deserialize};
+use serde::{Serialize, Serializer};
+
+static DEFAULT_PLACE: &'static str = include_str!("../assets/place.project.json");
 
 pub static PROJECT_FILENAME: &'static str = "default.project.json";
 pub static COMPAT_PROJECT_FILENAME: &'static str = "roblox-project.json";
@@ -24,6 +26,10 @@ struct SourceProject {
     name: String,
     tree: SourceProjectNode,
 
+    #[cfg_attr(not(feature = "plugins-enabled"), serde(skip_deserializing))]
+    #[serde(default = "Vec::new", skip_serializing_if = "Vec::is_empty")]
+    plugins: Vec<SourcePlugin>,
+
     #[serde(skip_serializing_if = "Option::is_none")]
     serve_port: Option<u16>,
 
@@ -33,12 +39,17 @@ struct SourceProject {
 
 impl SourceProject {
     /// Consumes the SourceProject and yields a Project, ready for prime-time.
-    pub fn into_project(self, project_file_location: &Path) -> Project {
+    pub fn into_project(mut self, project_file_location: &Path) -> Project {
         let tree = self.tree.into_project_node(project_file_location);
+        let plugins = self.plugins
+            .drain(..)
+            .map(|source_plugin| source_plugin.into_plugin(project_file_location))
+            .collect();
 
         Project {
             name: self.name,
             tree,
+            plugins,
             serve_port: self.serve_port,
             serve_place_ids: self.serve_place_ids,
             file_location: PathBuf::from(project_file_location),
@@ -46,16 +57,89 @@ impl SourceProject {
     }
 }
 
+/// An alternative serializer for `UnresolvedRbxValue` that uses the minimum
+/// representation of the value.
+///
+/// For example, the default Serialize impl might give you:
+///
+/// ```json
+/// {
+///     "Type": "Bool",
+///     "Value": true
+/// }
+/// ```
+///
+/// But in reality, users are expected to write just:
+///
+/// ```json
+/// true
+/// ```
+///
+/// This holds true for other values that might be ambiguous or just have more
+/// complicated representations like enums.
+fn serialize_unresolved_minimal<S>(unresolved: &UnresolvedRbxValue, serializer: S) -> Result<S::Ok, S::Error>
+    where S: Serializer
+{
+    match unresolved {
+        UnresolvedRbxValue::Ambiguous(_) => unresolved.serialize(serializer),
+        UnresolvedRbxValue::Concrete(concrete) => {
+            match concrete {
+                RbxValue::Bool { value } => value.serialize(serializer),
+                RbxValue::CFrame { value } => value.serialize(serializer),
+                RbxValue::Color3 { value } => value.serialize(serializer),
+                RbxValue::Color3uint8 { value } => value.serialize(serializer),
+                RbxValue::Content { value } => value.serialize(serializer),
+                RbxValue::Enum { value } => value.serialize(serializer),
+                RbxValue::Float32 { value } => value.serialize(serializer),
+                RbxValue::Int32 { value } => value.serialize(serializer),
+                RbxValue::String { value } => value.serialize(serializer),
+                RbxValue::UDim { value } => value.serialize(serializer),
+                RbxValue::UDim2 { value } => value.serialize(serializer),
+                RbxValue::Vector2 { value } => value.serialize(serializer),
+                RbxValue::Vector2int16 { value } => value.serialize(serializer),
+                RbxValue::Vector3 { value } => value.serialize(serializer),
+                RbxValue::Vector3int16 { value } => value.serialize(serializer),
+                _ => concrete.serialize(serializer),
+            }
+        },
+    }
+}
+
+/// A wrapper around serialize_unresolved_minimal that handles the HashMap case.
+fn serialize_unresolved_map<S>(value: &HashMap<String, UnresolvedRbxValue>, serializer: S) -> Result<S::Ok, S::Error>
+    where S: Serializer
+{
+    use serde::ser::SerializeMap;
+
+    #[derive(Serialize)]
+    struct Minimal<'a>(
+        #[serde(serialize_with = "serialize_unresolved_minimal")]
+        &'a UnresolvedRbxValue
+    );
+
+    let mut map = serializer.serialize_map(Some(value.len()))?;
+    for (k, v) in value {
+        map.serialize_key(k)?;
+        map.serialize_value(&Minimal(v))?;
+    }
+    map.end()
+}
+
 /// Similar to SourceProject, the structure of nodes in the project tree is
 /// slightly different on-disk than how we want to handle them in the rest of
 /// Rojo.
-#[derive(Debug, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 struct SourceProjectNode {
     #[serde(rename = "$className", skip_serializing_if = "Option::is_none")]
     class_name: Option<String>,
 
-    #[serde(rename = "$properties", default = "HashMap::new", skip_serializing_if = "HashMap::is_empty")]
-    properties: HashMap<String, RbxValue>,
+    #[serde(
+        rename = "$properties",
+        default = "HashMap::new",
+        skip_serializing_if = "HashMap::is_empty",
+        serialize_with = "serialize_unresolved_map",
+    )]
+    properties: HashMap<String, UnresolvedRbxValue>,
 
     #[serde(rename = "$ignoreUnknownInstances", skip_serializing_if = "Option::is_none")]
     ignore_unknown_instances: Option<bool>,
@@ -64,14 +148,14 @@ struct SourceProjectNode {
     path: Option<String>,
 
     #[serde(flatten)]
-    children: HashMap<String, SourceProjectNode>,
+    children: BTreeMap<String, SourceProjectNode>,
 }
 
 impl SourceProjectNode {
     /// Consumes the SourceProjectNode and turns it into a ProjectNode.
-    pub fn into_project_node(mut self, project_file_location: &Path) -> ProjectNode {
-        let children = self.children.drain()
-            .map(|(key, value)| (key, value.into_project_node(project_file_location)))
+    pub fn into_project_node(self, project_file_location: &Path) -> ProjectNode {
+        let children = self.children.iter()
+            .map(|(key, value)| (key.clone(), value.clone().into_project_node(project_file_location)))
             .collect();
 
         // Make sure that paths are absolute, transforming them by adding the
@@ -95,6 +179,26 @@ impl SourceProjectNode {
     }
 }
 
+#[derive(Debug, Serialize, Deserialize)]
+struct SourcePlugin {
+    path: String,
+}
+
+impl SourcePlugin {
+    pub fn into_plugin(self, project_file_location: &Path) -> Plugin {
+        let path = if Path::new(&self.path).is_absolute() {
+            PathBuf::from(self.path)
+        } else {
+            let project_folder_location = project_file_location.parent().unwrap();
+            project_folder_location.join(self.path)
+        };
+
+        Plugin {
+            path,
+        }
+    }
+}
+
 /// Error returned by Project::load_exact
 #[derive(Debug, Fail)]
 pub enum ProjectLoadExactError {
@@ -133,6 +237,7 @@ pub enum ProjectInitError {
     AlreadyExists(PathBuf),
     IoError(#[fail(cause)] io::Error),
     SaveError(#[fail(cause)] ProjectSaveError),
+    JsonError(#[fail(cause)] serde_json::Error),
 }
 
 impl fmt::Display for ProjectInitError {
@@ -141,6 +246,7 @@ impl fmt::Display for ProjectInitError {
             ProjectInitError::AlreadyExists(path) => write!(output, "Path {} already exists", path.display()),
             ProjectInitError::IoError(inner) => write!(output, "IO error: {}", inner),
             ProjectInitError::SaveError(inner) => write!(output, "{}", inner),
+            ProjectInitError::JsonError(inner) => write!(output, "{}", inner),
         }
     }
 }
@@ -158,8 +264,8 @@ pub enum ProjectSaveError {
 #[derive(Debug, Clone, PartialEq, Default, Serialize, Deserialize)]
 pub struct ProjectNode {
     pub class_name: Option<String>,
-    pub children: HashMap<String, ProjectNode>,
-    pub properties: HashMap<String, RbxValue>,
+    pub children: BTreeMap<String, ProjectNode>,
+    pub properties: HashMap<String, UnresolvedRbxValue>,
     pub ignore_unknown_instances: Option<bool>,
 
     #[serde(serialize_with = "crate::path_serializer::serialize_option")]
@@ -198,10 +304,30 @@ impl ProjectNode {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct Plugin {
+    pub path: PathBuf,
+}
+
+impl Plugin {
+    fn to_source_plugin(&self, project_file_location: &Path) -> SourcePlugin {
+        let project_folder_location = project_file_location.parent().unwrap();
+        let path = match self.path.strip_prefix(project_folder_location) {
+            Ok(stripped) => stripped.to_str().unwrap().replace("\\", "/"),
+            Err(_) => format!("{}", self.path.display()),
+        };
+
+        SourcePlugin {
+            path,
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct Project {
     pub name: String,
     pub tree: ProjectNode,
+    pub plugins: Vec<Plugin>,
     pub serve_port: Option<u16>,
     pub serve_place_ids: Option<HashSet<u64>>,
     pub file_location: PathBuf,
@@ -210,46 +336,16 @@ pub struct Project {
 impl Project {
     pub fn init_place(project_fuzzy_path: &Path) -> Result<PathBuf, ProjectInitError> {
         let project_path = Project::init_pick_path(project_fuzzy_path)?;
-        let project_folder_path = project_path.parent().unwrap();
         let project_name = if project_fuzzy_path == project_path {
             project_fuzzy_path.parent().unwrap().file_name().unwrap().to_str().unwrap()
         } else {
             project_fuzzy_path.file_name().unwrap().to_str().unwrap()
         };
 
-        let tree = ProjectNode {
-            class_name: Some(String::from("DataModel")),
-            children: hashmap! {
-                String::from("ReplicatedStorage") => ProjectNode {
-                    class_name: Some(String::from("ReplicatedStorage")),
-                    children: hashmap! {
-                        String::from("Source") => ProjectNode {
-                            path: Some(project_folder_path.join("src")),
-                            ..Default::default()
-                        },
-                    },
-                    ..Default::default()
-                },
-                String::from("HttpService") => ProjectNode {
-                    class_name: Some(String::from("HttpService")),
-                    properties: hashmap! {
-                        String::from("HttpEnabled") => RbxValue::Bool {
-                            value: true,
-                        },
-                    },
-                    ..Default::default()
-                },
-            },
-            ..Default::default()
-        };
+        let mut project = Project::load_from_str(DEFAULT_PLACE, &project_path)
+            .map_err(ProjectInitError::JsonError)?;
 
-        let project = Project {
-            name: project_name.to_string(),
-            tree,
-            serve_port: None,
-            serve_place_ids: None,
-            file_location: project_path.clone(),
-        };
+        project.name = project_name.to_owned();
 
         project.save()
             .map_err(ProjectInitError::SaveError)?;
@@ -274,6 +370,7 @@ impl Project {
         let project = Project {
             name: project_name.to_string(),
             tree,
+            plugins: Vec::new(),
             serve_port: None,
             serve_place_ids: None,
             file_location: project_path.clone(),
@@ -336,6 +433,12 @@ impl Project {
         }
     }
 
+    fn load_from_str(contents: &str, project_file_location: &Path) -> Result<Project, serde_json::Error> {
+        let parsed: SourceProject = serde_json::from_str(&contents)?;
+
+        Ok(parsed.into_project(project_file_location))
+    }
+
     pub fn load_fuzzy(fuzzy_project_location: &Path) -> Result<Project, ProjectLoadFuzzyError> {
         let project_path = Self::locate(fuzzy_project_location)
             .ok_or(ProjectLoadFuzzyError::NotFound)?;
@@ -383,10 +486,20 @@ impl Project {
         }
     }
 
+    pub fn folder_location(&self) -> &Path {
+        self.file_location.parent().unwrap()
+    }
+
     fn to_source_project(&self) -> SourceProject {
+        let plugins = self.plugins
+            .iter()
+            .map(|plugin| plugin.to_source_plugin(&self.file_location))
+            .collect();
+
         SourceProject {
             name: self.name.clone(),
             tree: self.tree.to_source_node(&self.file_location),
+            plugins,
             serve_port: self.serve_port,
             serve_place_ids: self.serve_place_ids.clone(),
         }

server/src/rbx_session.rs

@@ -6,16 +6,25 @@ use std::{
     sync::{Arc, Mutex},
 };
 
+use rlua::Lua;
 use serde_derive::{Serialize, Deserialize};
-use log::{info, trace};
-use rbx_tree::{RbxTree, RbxId};
+use log::{info, trace, error};
+use rbx_dom_weak::{RbxTree, RbxId};
 
 use crate::{
     project::{Project, ProjectNode},
     message_queue::MessageQueue,
     imfs::{Imfs, ImfsItem},
     path_map::PathMap,
-    rbx_snapshot::{snapshot_project_tree, snapshot_project_node, snapshot_imfs_path},
+    rbx_snapshot::{
+        SnapshotError,
+        SnapshotContext,
+        SnapshotPluginContext,
+        SnapshotPluginEntry,
+        snapshot_project_tree,
+        snapshot_project_node,
+        snapshot_imfs_path,
+    },
     snapshot_reconciler::{InstanceChanges, reify_root, reconcile_subtree},
 };
 
@@ -58,22 +67,60 @@ impl RbxSession {
         project: Arc<Project>,
         imfs: Arc<Mutex<Imfs>>,
         message_queue: Arc<MessageQueue<InstanceChanges>>,
-    ) -> RbxSession {
+    ) -> Result<RbxSession, SnapshotError> {
         let mut instances_per_path = PathMap::new();
         let mut metadata_per_instance = HashMap::new();
 
-        let tree = {
-            let temp_imfs = imfs.lock().unwrap();
-            reify_initial_tree(&project, &temp_imfs, &mut instances_per_path, &mut metadata_per_instance)
+        let plugin_context = if cfg!(feature = "server-plugins") {
+            let lua = Lua::new();
+            let mut callback_key = None;
+
+            lua.context(|context| {
+                let callback = context.load(r#"
+                    return function(snapshot)
+                        print("got my snapshot:", snapshot)
+                        print("name:", snapshot.name, "class name:", snapshot.className)
+                    end"#)
+                    .set_name("a cool plugin").unwrap()
+                    .call::<(), rlua::Function>(()).unwrap();
+
+                callback_key = Some(context.create_registry_value(callback).unwrap());
+            });
+
+            let plugins = vec![
+                SnapshotPluginEntry {
+                    file_name_filter: String::new(),
+                    callback: callback_key.unwrap(),
+                }
+            ];
+
+            Some(SnapshotPluginContext { lua, plugins })
+        } else {
+            None
         };
 
-        RbxSession {
+        let context = SnapshotContext {
+            plugin_context,
+        };
+
+        let tree = {
+            let temp_imfs = imfs.lock().unwrap();
+            reify_initial_tree(
+                &project,
+                &context,
+                &temp_imfs,
+                &mut instances_per_path,
+                &mut metadata_per_instance,
+            )?
+        };
+
+        Ok(RbxSession {
             tree,
             instances_per_path,
             metadata_per_instance,
             message_queue,
             imfs,
-        }
+        })
     }
 
     fn path_created_or_updated(&mut self, path: &Path) {
@@ -104,27 +151,37 @@ impl RbxSession {
                 .expect("Metadata did not exist for path")
                 .clone();
 
+            let context = SnapshotContext {
+                plugin_context: None,
+            };
+
             for instance_id in &instances_at_path {
                 let instance_metadata = self.metadata_per_instance.get(&instance_id)
                     .expect("Metadata for instance ID did not exist");
 
                 let maybe_snapshot = match &instance_metadata.project_definition {
                     Some((instance_name, project_node)) => {
-                        snapshot_project_node(&imfs, &project_node, Cow::Owned(instance_name.clone()))
-                            .unwrap_or_else(|_| panic!("Could not generate instance snapshot for path {}", path_to_snapshot.display()))
+                        snapshot_project_node(&context, &imfs, &project_node, Cow::Owned(instance_name.clone()))
+                            // .unwrap_or_else(|_| panic!("Could not generate instance snapshot for path {}", path_to_snapshot.display()))
                     },
                     None => {
-                        snapshot_imfs_path(&imfs, &path_to_snapshot, None)
-                            .unwrap_or_else(|_| panic!("Could not generate instance snapshot for path {}", path_to_snapshot.display()))
+                        snapshot_imfs_path(&context, &imfs, &path_to_snapshot, None)
+                            // .unwrap_or_else(|_| panic!("Could not generate instance snapshot for path {}", path_to_snapshot.display()))
                     },
                 };
 
                 let snapshot = match maybe_snapshot {
-                    Some(snapshot) => snapshot,
-                    None => {
+                    Ok(Some(snapshot)) => snapshot,
+                    Ok(None) => {
                         trace!("Path resulted in no snapshot being generated.");
                         return;
                     },
+                    Err(err) => {
+                        error!("Rojo couldn't turn one of the project's files into Roblox instances.");
+                        error!("Any changes to the file have been ignored.");
+                        error!("{}", err);
+                        return;
+                    },
                 };
 
                 trace!("Snapshot: {:#?}", snapshot);
@@ -194,29 +251,39 @@ impl RbxSession {
         &self.tree
     }
 
+    pub fn get_all_instance_metadata(&self) -> &HashMap<RbxId, MetadataPerInstance> {
+        &self.metadata_per_instance
+    }
+
     pub fn get_instance_metadata(&self, id: RbxId) -> Option<&MetadataPerInstance> {
         self.metadata_per_instance.get(&id)
     }
 }
 
-pub fn construct_oneoff_tree(project: &Project, imfs: &Imfs) -> RbxTree {
+pub fn construct_oneoff_tree(project: &Project, imfs: &Imfs) -> Result<RbxTree, SnapshotError> {
     let mut instances_per_path = PathMap::new();
     let mut metadata_per_instance = HashMap::new();
-    reify_initial_tree(project, imfs, &mut instances_per_path, &mut metadata_per_instance)
+    let context = SnapshotContext {
+        plugin_context: None,
+    };
+
+    reify_initial_tree(project, &context, imfs, &mut instances_per_path, &mut metadata_per_instance)
 }
 
 fn reify_initial_tree(
     project: &Project,
+    context: &SnapshotContext,
     imfs: &Imfs,
     instances_per_path: &mut PathMap<HashSet<RbxId>>,
     metadata_per_instance: &mut HashMap<RbxId, MetadataPerInstance>,
-) -> RbxTree {
-    let snapshot = snapshot_project_tree(imfs, project)
-        .expect("Could not snapshot project tree")
-        .expect("Project did not produce any instances");
+) -> Result<RbxTree, SnapshotError> {
+    let snapshot = match snapshot_project_tree(&context, imfs, project)? {
+        Some(snapshot) => snapshot,
+        None => panic!("Project did not produce any instances"),
+    };
 
     let mut changes = InstanceChanges::default();
     let tree = reify_root(&snapshot, instances_per_path, metadata_per_instance, &mut changes);
 
-    tree
+    Ok(tree)
 }

server/src/rbx_snapshot.rs

@@ -9,11 +9,13 @@ use std::{
     str,
 };
 
+use rlua::Lua;
 use failure::Fail;
 use log::info;
 use maplit::hashmap;
-use rbx_tree::{RbxTree, RbxValue, RbxInstanceProperties};
+use rbx_dom_weak::{RbxTree, RbxValue, RbxInstanceProperties};
 use serde_derive::{Serialize, Deserialize};
+use rbx_reflection::{try_resolve_value, ValueResolveError};
 
 use crate::{
     imfs::{
@@ -38,6 +40,53 @@ const INIT_MODULE_NAME: &str = "init.lua";
 const INIT_SERVER_NAME: &str = "init.server.lua";
 const INIT_CLIENT_NAME: &str = "init.client.lua";
 
+pub struct SnapshotContext {
+    pub plugin_context: Option<SnapshotPluginContext>,
+}
+
+/// Context that's only relevant to generating snapshots if there are plugins
+/// associated with the project.
+///
+/// It's possible that this needs some sort of extra nesting/filtering to
+/// support nested projects, since their plugins should only apply to
+/// themselves.
+pub struct SnapshotPluginContext {
+    pub lua: Lua,
+    pub plugins: Vec<SnapshotPluginEntry>,
+}
+
+pub struct SnapshotPluginEntry {
+    /// Simple file name suffix filter to avoid running plugins on every file
+    /// change.
+    pub file_name_filter: String,
+
+    /// A key into the Lua registry created by [`create_registry_value`] that
+    /// refers to a function that can be called to transform a file/instance
+    /// pair according to how the plugin needs to operate.
+    ///
+    /// [`create_registry_value`]: https://docs.rs/rlua/0.16.2/rlua/struct.Context.html#method.create_registry_value
+    pub callback: rlua::RegistryKey,
+}
+
+#[derive(Debug, Clone)]
+struct LuaRbxSnapshot(RbxSnapshotInstance<'static>);
+
+impl rlua::UserData for LuaRbxSnapshot {
+    fn add_methods<'lua, M: rlua::UserDataMethods<'lua, Self>>(methods: &mut M) {
+        methods.add_meta_method(rlua::MetaMethod::Index, |_context, this, key: String| {
+            match key.as_str() {
+                "name" => Ok(this.0.name.clone().into_owned()),
+                "className" => Ok(this.0.class_name.clone().into_owned()),
+                _ => Err(rlua::Error::RuntimeError(format!("{} is not a valid member of RbxSnapshotInstance", &key))),
+            }
+        });
+
+        methods.add_meta_method(rlua::MetaMethod::ToString, |_context, _this, _args: ()| {
+            Ok("RbxSnapshotInstance")
+        });
+    }
+}
+
 pub type SnapshotResult<'a> = Result<Option<RbxSnapshotInstance<'a>>, SnapshotError>;
 
 #[derive(Debug, Fail)]
@@ -57,6 +106,7 @@ pub enum SnapshotError {
     },
 
     XmlModelDecodeError {
+        #[fail(cause)]
         inner: rbx_xml::DecodeError,
         path: PathBuf,
     },
@@ -66,11 +116,30 @@ pub enum SnapshotError {
         path: PathBuf,
     },
 
+    CsvDecodeError {
+        #[fail(cause)]
+        inner: csv::Error,
+        path: PathBuf,
+    },
+
     ProjectNodeUnusable,
 
     ProjectNodeInvalidTransmute {
         partition_path: PathBuf,
     },
+
+    PropertyResolveError {
+        #[fail(cause)]
+        inner: ValueResolveError,
+    },
+}
+
+impl From<ValueResolveError> for SnapshotError {
+    fn from(inner: ValueResolveError) -> SnapshotError {
+        SnapshotError::PropertyResolveError {
+            inner,
+        }
+    }
 }
 
 impl fmt::Display for SnapshotError {
@@ -89,6 +158,9 @@ impl fmt::Display for SnapshotError {
             SnapshotError::BinaryModelDecodeError { inner, path } => {
                 write!(output, "Malformed rbxm model: {:?} in path {}", inner, path.display())
             },
+            SnapshotError::CsvDecodeError { inner, path } => {
+                write!(output, "Malformed csv file: {} in path {}", inner, path.display())
+            },
             SnapshotError::ProjectNodeUnusable => {
                 write!(output, "Rojo project nodes must specify either $path or $className.")
             },
@@ -99,24 +171,27 @@ impl fmt::Display for SnapshotError {
                 writeln!(output, "")?;
                 writeln!(output, "Partition target ($path): {}", partition_path.display())
             },
+            SnapshotError::PropertyResolveError { inner } => write!(output, "{}", inner),
         }
     }
 }
 
 pub fn snapshot_project_tree<'source>(
+    context: &SnapshotContext,
     imfs: &'source Imfs,
     project: &'source Project,
 ) -> SnapshotResult<'source> {
-    snapshot_project_node(imfs, &project.tree, Cow::Borrowed(&project.name))
+    snapshot_project_node(context, imfs, &project.tree, Cow::Borrowed(&project.name))
 }
 
 pub fn snapshot_project_node<'source>(
+    context: &SnapshotContext,
     imfs: &'source Imfs,
     node: &ProjectNode,
     instance_name: Cow<'source, str>,
 ) -> SnapshotResult<'source> {
     let maybe_snapshot = match &node.path {
-        Some(path) => snapshot_imfs_path(imfs, &path, Some(instance_name.clone()))?,
+        Some(path) => snapshot_imfs_path(context, imfs, &path, Some(instance_name.clone()))?,
         None => match &node.class_name {
             Some(_class_name) => Some(RbxSnapshotInstance {
                 name: instance_name.clone(),
@@ -170,13 +245,14 @@ pub fn snapshot_project_node<'source>(
     }
 
     for (child_name, child_project_node) in &node.children {
-        if let Some(child) = snapshot_project_node(imfs, child_project_node, Cow::Owned(child_name.clone()))? {
+        if let Some(child) = snapshot_project_node(context, imfs, child_project_node, Cow::Owned(child_name.clone()))? {
             snapshot.children.push(child);
         }
     }
 
     for (key, value) in &node.properties {
-        snapshot.properties.insert(key.clone(), value.clone());
+        let resolved_value = try_resolve_value(&snapshot.class_name, key, value)?;
+        snapshot.properties.insert(key.clone(), resolved_value);
     }
 
     if let Some(ignore_unknown_instances) = node.ignore_unknown_instances {
@@ -189,6 +265,7 @@ pub fn snapshot_project_node<'source>(
 }
 
 pub fn snapshot_imfs_path<'source>(
+    context: &SnapshotContext,
     imfs: &'source Imfs,
     path: &Path,
     instance_name: Option<Cow<'source, str>>,
@@ -196,23 +273,25 @@ pub fn snapshot_imfs_path<'source>(
     // If the given path doesn't exist in the in-memory filesystem, we consider
     // that an error.
     match imfs.get(path) {
-        Some(imfs_item) => snapshot_imfs_item(imfs, imfs_item, instance_name),
+        Some(imfs_item) => snapshot_imfs_item(context, imfs, imfs_item, instance_name),
         None => return Err(SnapshotError::DidNotExist(path.to_owned())),
     }
 }
 
 fn snapshot_imfs_item<'source>(
+    context: &SnapshotContext,
     imfs: &'source Imfs,
     item: &'source ImfsItem,
     instance_name: Option<Cow<'source, str>>,
 ) -> SnapshotResult<'source> {
     match item {
-        ImfsItem::File(file) => snapshot_imfs_file(file, instance_name),
-        ImfsItem::Directory(directory) => snapshot_imfs_directory(imfs, directory, instance_name),
+        ImfsItem::File(file) => snapshot_imfs_file(context, file, instance_name),
+        ImfsItem::Directory(directory) => snapshot_imfs_directory(context, imfs, directory, instance_name),
     }
 }
 
 fn snapshot_imfs_directory<'source>(
+    context: &SnapshotContext,
     imfs: &'source Imfs,
     directory: &'source ImfsDirectory,
     instance_name: Option<Cow<'source, str>>,
@@ -229,11 +308,11 @@ fn snapshot_imfs_directory<'source>(
         });
 
     let mut snapshot = if directory.children.contains(&init_path) {
-        snapshot_imfs_path(imfs, &init_path, Some(snapshot_name))?.unwrap()
+        snapshot_imfs_path(context, imfs, &init_path, Some(snapshot_name))?.unwrap()
     } else if directory.children.contains(&init_server_path) {
-        snapshot_imfs_path(imfs, &init_server_path, Some(snapshot_name))?.unwrap()
+        snapshot_imfs_path(context, imfs, &init_server_path, Some(snapshot_name))?.unwrap()
     } else if directory.children.contains(&init_client_path) {
-        snapshot_imfs_path(imfs, &init_client_path, Some(snapshot_name))?.unwrap()
+        snapshot_imfs_path(context, imfs, &init_client_path, Some(snapshot_name))?.unwrap()
     } else {
         RbxSnapshotInstance {
             class_name: Cow::Borrowed("Folder"),
@@ -262,7 +341,7 @@ fn snapshot_imfs_directory<'source>(
                 // them here.
             },
             _ => {
-                if let Some(child) = snapshot_imfs_path(imfs, child_path, None)? {
+                if let Some(child) = snapshot_imfs_path(context, imfs, child_path, None)? {
                     snapshot.children.push(child);
                 }
             },
@@ -273,6 +352,7 @@ fn snapshot_imfs_directory<'source>(
 }
 
 fn snapshot_imfs_file<'source>(
+    context: &SnapshotContext,
     file: &'source ImfsFile,
     instance_name: Option<Cow<'source, str>>,
 ) -> SnapshotResult<'source> {
@@ -308,6 +388,20 @@ fn snapshot_imfs_file<'source>(
         info!("File generated no snapshot: {}", file.path.display());
     }
 
+    if let Some(snapshot) = maybe_snapshot.as_ref() {
+        if let Some(plugin_context) = &context.plugin_context {
+            for plugin in &plugin_context.plugins {
+                let owned_snapshot = snapshot.get_owned();
+                let registry_key = &plugin.callback;
+
+                plugin_context.lua.context(move |context| {
+                    let callback: rlua::Function = context.registry_value(registry_key).unwrap();
+                    callback.call::<_, ()>(LuaRbxSnapshot(owned_snapshot)).unwrap();
+                });
+            }
+        }
+    }
+
     Ok(maybe_snapshot)
 }
 
@@ -391,16 +485,87 @@ fn snapshot_txt_file<'source>(
 fn snapshot_csv_file<'source>(
     file: &'source ImfsFile,
 ) -> SnapshotResult<'source> {
+    /// Struct that holds any valid row from a Roblox CSV translation table.
+    ///
+    /// We manually deserialize into this table from CSV, but let JSON handle
+    /// serializing.
+    #[derive(Debug, Default, Serialize)]
+    #[serde(rename_all = "camelCase")]
+    struct LocalizationEntry<'a> {
+        #[serde(skip_serializing_if = "Option::is_none")]
+        key: Option<&'a str>,
+
+        #[serde(skip_serializing_if = "Option::is_none")]
+        context: Option<&'a str>,
+
+        #[serde(skip_serializing_if = "Option::is_none")]
+        example: Option<&'a str>,
+
+        #[serde(skip_serializing_if = "Option::is_none")]
+        source: Option<&'a str>,
+
+        values: HashMap<&'a str, &'a str>,
+    }
+
     let instance_name = file.path
         .file_stem().expect("Could not extract file stem")
         .to_str().expect("Could not convert path to UTF-8");
 
-    let entries: Vec<LocalizationEntryJson> = csv::Reader::from_reader(file.contents.as_slice())
-        .deserialize()
-        // TODO: Propagate error upward instead of panicking
-        .map(|result| result.expect("Malformed localization table found!"))
-        .map(LocalizationEntryCsv::to_json)
-        .collect();
+    // Normally, we'd be able to let the csv crate construct our struct for us.
+    //
+    // However, because of a limitation with Serde's 'flatten' feature, it's not
+    // possible presently to losslessly collect extra string values while using
+    // csv+Serde.
+    //
+    // https://github.com/BurntSushi/rust-csv/issues/151
+    let mut reader = csv::Reader::from_reader(file.contents.as_slice());
+
+    let headers = reader.headers()
+        .map_err(|inner| SnapshotError::CsvDecodeError {
+            inner,
+            path: file.path.to_path_buf(),
+        })?
+        .clone();
+
+    let mut records = Vec::new();
+
+    for record in reader.into_records() {
+        let record = record
+            .map_err(|inner| SnapshotError::CsvDecodeError {
+                inner,
+                path: file.path.to_path_buf(),
+            })?;
+
+        records.push(record);
+    }
+
+    let mut entries = Vec::new();
+
+    for record in &records {
+        let mut entry = LocalizationEntry::default();
+
+        for (header, value) in headers.iter().zip(record.into_iter()) {
+            if header.is_empty() || value.is_empty() {
+                continue;
+            }
+
+            match header {
+                "Key" => entry.key = Some(value),
+                "Source" => entry.source = Some(value),
+                "Context" => entry.context = Some(value),
+                "Example" => entry.example = Some(value),
+                _ => {
+                    entry.values.insert(header, value);
+                }
+            }
+        }
+
+        if entry.key.is_none() && entry.source.is_none() {
+            continue;
+        }
+
+        entries.push(entry);
+    }
 
     let table_contents = serde_json::to_string(&entries)
         .expect("Could not encode JSON for localization table");
@@ -422,39 +587,6 @@ fn snapshot_csv_file<'source>(
     }))
 }
 
-#[derive(Debug, Serialize, Deserialize)]
-#[serde(rename_all = "PascalCase")]
-struct LocalizationEntryCsv {
-    key: String,
-    context: String,
-    example: String,
-    source: String,
-    #[serde(flatten)]
-    values: HashMap<String, String>,
-}
-
-impl LocalizationEntryCsv {
-    fn to_json(self) -> LocalizationEntryJson {
-        LocalizationEntryJson {
-            key: self.key,
-            context: self.context,
-            example: self.example,
-            source: self.source,
-            values: self.values,
-        }
-    }
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-#[serde(rename_all = "camelCase")]
-struct LocalizationEntryJson {
-    key: String,
-    context: String,
-    example: String,
-    source: String,
-    values: HashMap<String, String>,
-}
-
 fn snapshot_json_model_file<'source>(
     file: &'source ImfsFile,
 ) -> SnapshotResult<'source> {

server/src/snapshot_reconciler.rs

@@ -10,7 +10,7 @@ use std::{
     str,
 };
 
-use rbx_tree::{RbxTree, RbxId, RbxInstanceProperties, RbxValue};
+use rbx_dom_weak::{RbxTree, RbxId, RbxInstanceProperties, RbxValue};
 use serde_derive::{Serialize, Deserialize};
 
 use crate::{
@@ -64,7 +64,7 @@ impl InstanceChanges {
 
 /// A lightweight, hierarchical representation of an instance that can be
 /// applied to the tree.
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
 pub struct RbxSnapshotInstance<'a> {
     pub name: Cow<'a, str>,
     pub class_name: Cow<'a, str>,
@@ -73,6 +73,22 @@ pub struct RbxSnapshotInstance<'a> {
     pub metadata: MetadataPerInstance,
 }
 
+impl<'a> RbxSnapshotInstance<'a> {
+    pub fn get_owned(&'a self) -> RbxSnapshotInstance<'static> {
+        let children: Vec<RbxSnapshotInstance<'static>> = self.children.iter()
+            .map(RbxSnapshotInstance::get_owned)
+            .collect();
+
+        RbxSnapshotInstance {
+            name: Cow::Owned(self.name.clone().into_owned()),
+            class_name: Cow::Owned(self.class_name.clone().into_owned()),
+            properties: self.properties.clone(),
+            children,
+            metadata: self.metadata.clone(),
+        }
+    }
+}
+
 impl<'a> PartialOrd for RbxSnapshotInstance<'a> {
     fn partial_cmp(&self, other: &RbxSnapshotInstance) -> Option<Ordering> {
         Some(self.name.cmp(&other.name)
@@ -137,7 +153,7 @@ pub fn reify_subtree(
     instance_per_path: &mut PathMap<HashSet<RbxId>>,
     metadata_per_instance: &mut HashMap<RbxId, MetadataPerInstance>,
     changes: &mut InstanceChanges,
-) {
+) -> RbxId {
     let instance = reify_core(snapshot);
     let id = tree.insert_instance(instance, parent_id);
 
@@ -148,6 +164,8 @@ pub fn reify_subtree(
     for child in &snapshot.children {
         reify_subtree(child, tree, id, instance_per_path, metadata_per_instance, changes);
     }
+
+    id
 }
 
 fn reify_metadata(
@@ -206,6 +224,9 @@ fn reify_core(snapshot: &RbxSnapshotInstance) -> RbxInstanceProperties {
     instance
 }
 
+/// Updates the given instance to match the properties defined on the snapshot.
+///
+/// Returns whether any changes were applied.
 fn reconcile_instance_properties(instance: &mut RbxInstanceProperties, snapshot: &RbxSnapshotInstance) -> bool {
     let mut has_diffs = false;
 
@@ -263,6 +284,8 @@ fn reconcile_instance_properties(instance: &mut RbxInstanceProperties, snapshot:
     has_diffs
 }
 
+/// Updates the children of the instance in the `RbxTree` to match the children
+/// of the `RbxSnapshotInstance`. Order will be updated to match.
 fn reconcile_instance_children(
     tree: &mut RbxTree,
     id: RbxId,
@@ -271,12 +294,21 @@ fn reconcile_instance_children(
     metadata_per_instance: &mut HashMap<RbxId, MetadataPerInstance>,
     changes: &mut InstanceChanges,
 ) {
-    let mut visited_snapshot_indices = HashSet::new();
-
-    let mut children_to_update: Vec<(RbxId, &RbxSnapshotInstance)> = Vec::new();
-    let mut children_to_add: Vec<&RbxSnapshotInstance> = Vec::new();
+    // These lists are kept so that we can apply all the changes we figure out
+    let mut children_to_maybe_update: Vec<(RbxId, &RbxSnapshotInstance)> = Vec::new();
+    let mut children_to_add: Vec<(usize, &RbxSnapshotInstance)> = Vec::new();
     let mut children_to_remove: Vec<RbxId> = Vec::new();
 
+    // This map is used once we're done mutating children to sort them according
+    // to the order specified in the snapshot. Without it, a snapshot with a new
+    // child prepended will cause the RbxTree instance to have out-of-order
+    // children and would make Rojo non-deterministic.
+    let mut ids_to_snapshot_indices = HashMap::new();
+
+    // Since we have to enumerate the children of both the RbxTree instance and
+    // our snapshot, we keep a set of the snapshot children we've seen.
+    let mut visited_snapshot_indices = vec![false; snapshot.children.len()];
+
     let children_ids = tree.get_instance(id).unwrap().get_children_ids();
 
     // Find all instances that were removed or updated, which we derive by
@@ -287,7 +319,7 @@ fn reconcile_instance_children(
         // Locate a matching snapshot for this instance
         let mut matching_snapshot = None;
         for (snapshot_index, child_snapshot) in snapshot.children.iter().enumerate() {
-            if visited_snapshot_indices.contains(&snapshot_index) {
+            if visited_snapshot_indices[snapshot_index] {
                 continue;
             }
 
@@ -295,7 +327,8 @@ fn reconcile_instance_children(
             // similar. This heuristic is similar to React's reconciliation
             // strategy.
             if child_snapshot.name == child_instance.name {
-                visited_snapshot_indices.insert(snapshot_index);
+                ids_to_snapshot_indices.insert(child_id, snapshot_index);
+                visited_snapshot_indices[snapshot_index] = true;
                 matching_snapshot = Some(child_snapshot);
                 break;
             }
@@ -303,26 +336,23 @@ fn reconcile_instance_children(
 
         match matching_snapshot {
             Some(child_snapshot) => {
-                children_to_update.push((child_instance.get_id(), child_snapshot));
-            },
+                children_to_maybe_update.push((child_instance.get_id(), child_snapshot));
+            }
             None => {
                 children_to_remove.push(child_instance.get_id());
-            },
+            }
         }
     }
 
     // Find all instancs that were added, which is just the snapshots we didn't
     // match up to existing instances above.
     for (snapshot_index, child_snapshot) in snapshot.children.iter().enumerate() {
-        if !visited_snapshot_indices.contains(&snapshot_index) {
-            children_to_add.push(child_snapshot);
+        if !visited_snapshot_indices[snapshot_index] {
+            children_to_add.push((snapshot_index, child_snapshot));
         }
     }
 
-    for child_snapshot in &children_to_add {
-        reify_subtree(child_snapshot, tree, id, instance_per_path, metadata_per_instance, changes);
-    }
-
+    // Apply all of our removals we gathered from our diff
     for child_id in &children_to_remove {
         if let Some(subtree) = tree.remove_instance(*child_id) {
             for id in subtree.iter_all_ids() {
@@ -332,7 +362,18 @@ fn reconcile_instance_children(
         }
     }
 
-    for (child_id, child_snapshot) in &children_to_update {
+    // Apply all of our children additions
+    for (snapshot_index, child_snapshot) in &children_to_add {
+        let id = reify_subtree(child_snapshot, tree, id, instance_per_path, metadata_per_instance, changes);
+        ids_to_snapshot_indices.insert(id, *snapshot_index);
+    }
+
+    // Apply any updates that might have updates
+    for (child_id, child_snapshot) in &children_to_maybe_update {
         reconcile_subtree(tree, *child_id, child_snapshot, instance_per_path, metadata_per_instance, changes);
     }
+
+    // Apply the sort mapping defined by ids_to_snapshot_indices above
+    let instance = tree.get_instance_mut(id).unwrap();
+    instance.sort_children_unstable_by_key(|id| ids_to_snapshot_indices.get(&id).unwrap());
 }

server/src/visualize.rs

@@ -1,4 +1,5 @@
 use std::{
+    collections::HashMap,
     fmt,
     io::Write,
     path::Path,
@@ -6,12 +7,13 @@ use std::{
 };
 
 use log::warn;
-use rbx_tree::RbxId;
+use rbx_dom_weak::{RbxTree, RbxId};
 
 use crate::{
     imfs::{Imfs, ImfsItem},
     rbx_session::RbxSession,
-    web::PublicInstanceMetadata,
+    web::api::PublicInstanceMetadata,
+    rbx_session::MetadataPerInstance,
 };
 
 static GRAPHVIZ_HEADER: &str = r#"
@@ -53,42 +55,59 @@ pub fn graphviz_to_svg(source: &str) -> Option<String> {
     Some(String::from_utf8(output.stdout).expect("Failed to parse stdout as UTF-8"))
 }
 
+pub struct VisualizeRbxTree<'a, 'b> {
+    pub tree: &'a RbxTree,
+    pub metadata: &'b HashMap<RbxId, MetadataPerInstance>,
+}
+
+impl<'a, 'b> fmt::Display for VisualizeRbxTree<'a, 'b> {
+    fn fmt(&self, output: &mut fmt::Formatter) -> fmt::Result {
+        writeln!(output, "{}", GRAPHVIZ_HEADER)?;
+
+        visualize_instance(&self.tree, self.tree.get_root_id(), &self.metadata, output)?;
+
+        writeln!(output, "}}")
+    }
+}
+
 /// A Display wrapper struct to visualize an RbxSession as SVG.
 pub struct VisualizeRbxSession<'a>(pub &'a RbxSession);
 
 impl<'a> fmt::Display for VisualizeRbxSession<'a> {
     fn fmt(&self, output: &mut fmt::Formatter) -> fmt::Result {
-        writeln!(output, "{}", GRAPHVIZ_HEADER)?;
-
-        visualize_rbx_node(self.0, self.0.get_tree().get_root_id(), output)?;
-
-        writeln!(output, "}}")?;
-
-        Ok(())
+        writeln!(output, "{}", VisualizeRbxTree {
+            tree: self.0.get_tree(),
+            metadata: self.0.get_all_instance_metadata(),
+        })
     }
 }
 
-fn visualize_rbx_node(session: &RbxSession, id: RbxId, output: &mut fmt::Formatter) -> fmt::Result {
-    let node = session.get_tree().get_instance(id).unwrap();
+fn visualize_instance(
+    tree: &RbxTree,
+    id: RbxId,
+    metadata: &HashMap<RbxId, MetadataPerInstance>,
+    output: &mut fmt::Formatter,
+) -> fmt::Result {
+    let instance = tree.get_instance(id).unwrap();
 
-    let mut node_label = format!("{}|{}|{}", node.name, node.class_name, id);
+    let mut instance_label = format!("{}|{}|{}", instance.name, instance.class_name, id);
 
-    if let Some(session_metadata) = session.get_instance_metadata(id) {
+    if let Some(session_metadata) = metadata.get(&id) {
         let metadata = PublicInstanceMetadata::from_session_metadata(session_metadata);
-        node_label.push('|');
-        node_label.push_str(&serde_json::to_string(&metadata).unwrap());
+        instance_label.push('|');
+        instance_label.push_str(&serde_json::to_string(&metadata).unwrap());
     }
 
-    node_label = node_label
+    instance_label = instance_label
         .replace("\"", "&quot;")
         .replace("{", "\\{")
         .replace("}", "\\}");
 
-    writeln!(output, "    \"{}\" [label=\"{}\"]", id, node_label)?;
+    writeln!(output, "    \"{}\" [label=\"{}\"]", id, instance_label)?;
 
-    for &child_id in node.get_children_ids() {
+    for &child_id in instance.get_children_ids() {
         writeln!(output, "    \"{}\" -> \"{}\"", id, child_id)?;
-        visualize_rbx_node(session, child_id, output)?;
+        visualize_instance(tree, child_id, metadata, output)?;
     }
 
     Ok(())

server/src/web/api.rs

@@ -1,32 +1,36 @@
-//! Defines Rojo's web interface that all clients use to communicate with a
-//! running live-sync session.
+//! Defines Rojo's HTTP API, all under /api. These endpoints generally return
+//! JSON.
 
 use std::{
     borrow::Cow,
     collections::{HashMap, HashSet},
-    sync::{mpsc, Arc},
+    sync::Arc,
 };
 
-use serde_derive::{Serialize, Deserialize};
-use log::trace;
-use rouille::{
-    self,
-    router,
+use futures::{
+    future::{self, IntoFuture},
+    Future,
+    sync::oneshot,
+};
+use hyper::{
+    service::Service,
+    header,
+    StatusCode,
+    Method,
+    Body,
     Request,
     Response,
 };
-use rbx_tree::{RbxId, RbxInstance};
+use serde_derive::{Serialize, Deserialize};
+use rbx_dom_weak::{RbxId, RbxInstance};
 
 use crate::{
     live_session::LiveSession,
     session_id::SessionId,
     snapshot_reconciler::InstanceChanges,
-    visualize::{VisualizeRbxSession, VisualizeImfs, graphviz_to_svg},
     rbx_session::{MetadataPerInstance},
 };
 
-static HOME_CONTENT: &str = include_str!("../assets/index.html");
-
 /// Contains the instance metadata relevant to Rojo clients.
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
@@ -43,7 +47,7 @@ impl PublicInstanceMetadata {
 }
 
 /// Used to attach metadata specific to Rojo to instances, which come from the
-/// rbx_tree crate.
+/// rbx_dom_weak crate.
 ///
 /// Both fields are wrapped in Cow in order to make owned-vs-borrowed simpler
 /// for tests.
@@ -82,121 +86,133 @@ pub struct SubscribeResponse<'a> {
     pub messages: Cow<'a, [InstanceChanges]>,
 }
 
-pub struct Server {
+fn response_json<T: serde::Serialize>(value: T) -> Response<Body> {
+    let serialized = match serde_json::to_string(&value) {
+        Ok(v) => v,
+        Err(err) => {
+            return Response::builder()
+                .status(StatusCode::BAD_REQUEST)
+                .header(header::CONTENT_TYPE, "text/plain")
+                .body(Body::from(err.to_string()))
+                .unwrap();
+        },
+    };
+
+    Response::builder()
+        .header(header::CONTENT_TYPE, "application/json")
+        .body(Body::from(serialized))
+        .unwrap()
+}
+
+pub struct ApiService {
     live_session: Arc<LiveSession>,
     server_version: &'static str,
 }
 
-impl Server {
-    pub fn new(live_session: Arc<LiveSession>) -> Server {
-        Server {
+impl Service for ApiService {
+    type ReqBody = Body;
+    type ResBody = Body;
+    type Error = hyper::Error;
+    type Future = Box<dyn Future<Item = hyper::Response<Self::ReqBody>, Error = Self::Error> + Send>;
+
+    fn call(&mut self, request: hyper::Request<Self::ReqBody>) -> Self::Future {
+        let response = match (request.method(), request.uri().path()) {
+            (&Method::GET, "/api/rojo") => self.handle_api_rojo(),
+            (&Method::GET, path) if path.starts_with("/api/read/") => self.handle_api_read(request),
+            (&Method::GET, path) if path.starts_with("/api/subscribe/") => {
+                return self.handle_api_subscribe(request);
+            }
+            _ => {
+                Response::builder()
+                    .status(StatusCode::NOT_FOUND)
+                    .body(Body::empty())
+                    .unwrap()
+            }
+        };
+
+        Box::new(future::ok(response))
+    }
+}
+
+impl ApiService {
+    pub fn new(live_session: Arc<LiveSession>) -> ApiService {
+        ApiService {
             live_session,
             server_version: env!("CARGO_PKG_VERSION"),
         }
     }
 
-    #[allow(unreachable_code)]
-    pub fn handle_request(&self, request: &Request) -> Response {
-        trace!("Request {} {}", request.method(), request.url());
-
-        router!(request,
-            (GET) (/) => {
-                self.handle_home()
-            },
-            (GET) (/api/rojo) => {
-                self.handle_api_rojo()
-            },
-            (GET) (/api/subscribe/{ cursor: u32 }) => {
-                self.handle_api_subscribe(cursor)
-            },
-            (GET) (/api/read/{ id_list: String }) => {
-                let requested_ids: Option<Vec<RbxId>> = id_list
-                    .split(',')
-                    .map(RbxId::parse_str)
-                    .collect();
-
-                self.handle_api_read(requested_ids)
-            },
-            (GET) (/visualize/rbx) => {
-                self.handle_visualize_rbx()
-            },
-            (GET) (/visualize/imfs) => {
-                self.handle_visualize_imfs()
-            },
-            _ => Response::empty_404()
-        )
-    }
-
-    pub fn listen(self, port: u16) {
-        let address = format!("0.0.0.0:{}", port);
-
-        rouille::start_server(address, move |request| self.handle_request(request));
-    }
-
-    fn handle_home(&self) -> Response {
-        Response::html(HOME_CONTENT)
-    }
-
     /// Get a summary of information about the server
-    fn handle_api_rojo(&self) -> Response {
+    fn handle_api_rojo(&self) -> Response<Body> {
         let rbx_session = self.live_session.rbx_session.lock().unwrap();
         let tree = rbx_session.get_tree();
 
-        Response::json(&ServerInfoResponse {
+        response_json(&ServerInfoResponse {
             server_version: self.server_version,
             protocol_version: 2,
-            session_id: self.live_session.session_id,
-            expected_place_ids: self.live_session.project.serve_place_ids.clone(),
+            session_id: self.live_session.session_id(),
+            expected_place_ids: self.live_session.serve_place_ids().clone(),
             root_instance_id: tree.get_root_id(),
         })
     }
 
     /// Retrieve any messages past the given cursor index, and if
     /// there weren't any, subscribe to receive any new messages.
-    fn handle_api_subscribe(&self, cursor: u32) -> Response {
+    fn handle_api_subscribe(&self, request: Request<Body>) -> <ApiService as Service>::Future {
+        let argument = &request.uri().path()["/api/subscribe/".len()..];
+        let cursor: u32 = match argument.parse() {
+            Ok(v) => v,
+            Err(err) => {
+                return Box::new(future::ok(Response::builder()
+                    .status(StatusCode::BAD_REQUEST)
+                    .header(header::CONTENT_TYPE, "text/plain")
+                    .body(Body::from(err.to_string()))
+                    .unwrap()));
+            },
+        };
+
         let message_queue = Arc::clone(&self.live_session.message_queue);
+        let session_id = self.live_session.session_id();
 
-        // Did the client miss any messages since the last subscribe?
-        {
-            let (new_cursor, new_messages) = message_queue.get_messages_since(cursor);
+        let (tx, rx) = oneshot::channel();
+        message_queue.subscribe(cursor, tx);
 
-            if !new_messages.is_empty() {
-                return Response::json(&SubscribeResponse {
-                    session_id: self.live_session.session_id,
-                    messages: Cow::Borrowed(&new_messages),
+        let result = rx.into_future()
+            .and_then(move |(new_cursor, new_messages)| {
+                Box::new(future::ok(response_json(SubscribeResponse {
+                    session_id: session_id,
+                    messages: Cow::Owned(new_messages),
                     message_cursor: new_cursor,
-                })
-            }
-        }
-
-        let (tx, rx) = mpsc::channel();
-
-        let sender_id = message_queue.subscribe(tx);
-
-        match rx.recv() {
-            Ok(_) => (),
-            Err(_) => return Response::text("error!").with_status_code(500),
-        }
-
-        message_queue.unsubscribe(sender_id);
-
-        {
-            let (new_cursor, new_messages) = message_queue.get_messages_since(cursor);
-
-            return Response::json(&SubscribeResponse {
-                session_id: self.live_session.session_id,
-                messages: Cow::Owned(new_messages),
-                message_cursor: new_cursor,
+                })))
             })
-        }
+            .or_else(|e| {
+                Box::new(future::ok(Response::builder()
+                    .status(500)
+                    .body(Body::from(format!("Internal Error: {:?}", e)))
+                    .unwrap()))
+            });
+
+        Box::new(result)
     }
 
-    fn handle_api_read(&self, requested_ids: Option<Vec<RbxId>>) -> Response {
+    fn handle_api_read(&self, request: Request<Body>) -> Response<Body> {
+        let argument = &request.uri().path()["/api/read/".len()..];
+        let requested_ids: Option<Vec<RbxId>> = argument
+            .split(',')
+            .map(RbxId::parse_str)
+            .collect();
+
         let message_queue = Arc::clone(&self.live_session.message_queue);
 
         let requested_ids = match requested_ids {
             Some(id) => id,
-            None => return rouille::Response::text("Malformed ID list").with_status_code(400),
+            None => {
+                return Response::builder()
+                    .status(StatusCode::BAD_REQUEST)
+                    .header(header::CONTENT_TYPE, "text/plain")
+                    .body(Body::from("Malformed ID list"))
+                    .unwrap();
+            },
         };
 
         let rbx_session = self.live_session.rbx_session.lock().unwrap();
@@ -228,30 +244,10 @@ impl Server {
             }
         }
 
-        Response::json(&ReadResponse {
-            session_id: self.live_session.session_id,
+        response_json(&ReadResponse {
+            session_id: self.live_session.session_id(),
             message_cursor,
             instances,
         })
     }
-
-    fn handle_visualize_rbx(&self) -> Response {
-        let rbx_session = self.live_session.rbx_session.lock().unwrap();
-        let dot_source = format!("{}", VisualizeRbxSession(&rbx_session));
-
-        match graphviz_to_svg(&dot_source) {
-            Some(svg) => Response::svg(svg),
-            None => Response::text(dot_source),
-        }
-    }
-
-    fn handle_visualize_imfs(&self) -> Response {
-        let imfs = self.live_session.imfs.lock().unwrap();
-        let dot_source = format!("{}", VisualizeImfs(&imfs));
-
-        match graphviz_to_svg(&dot_source) {
-            Some(svg) => Response::svg(svg),
-            None => Response::text(dot_source),
-        }
-    }
 }

server/src/web/interface.rs

@@ -0,0 +1,121 @@
+//! Defines the HTTP-based UI. These endpoints generally return HTML and SVG.
+
+use std::sync::Arc;
+
+use futures::{future, Future};
+use hyper::{
+    service::Service,
+    header,
+    Body,
+    Method,
+    StatusCode,
+    Request,
+    Response,
+};
+use ritz::html;
+
+use crate::{
+    live_session::LiveSession,
+    visualize::{VisualizeRbxSession, VisualizeImfs, graphviz_to_svg},
+};
+
+static HOME_CSS: &str = include_str!("../../assets/index.css");
+
+pub struct InterfaceService {
+    live_session: Arc<LiveSession>,
+    server_version: &'static str,
+}
+
+impl Service for InterfaceService {
+    type ReqBody = Body;
+    type ResBody = Body;
+    type Error = hyper::Error;
+    type Future = Box<dyn Future<Item = Response<Self::ReqBody>, Error = Self::Error> + Send>;
+
+    fn call(&mut self, request: Request<Self::ReqBody>) -> Self::Future {
+        let response = match (request.method(), request.uri().path()) {
+            (&Method::GET, "/") => self.handle_home(),
+            (&Method::GET, "/visualize/rbx") => self.handle_visualize_rbx(),
+            (&Method::GET, "/visualize/imfs") => self.handle_visualize_imfs(),
+            _ => Response::builder()
+                .status(StatusCode::NOT_FOUND)
+                .body(Body::empty())
+                .unwrap(),
+        };
+
+        Box::new(future::ok(response))
+    }
+}
+
+impl InterfaceService {
+    pub fn new(live_session: Arc<LiveSession>) -> InterfaceService {
+        InterfaceService {
+            live_session,
+            server_version: env!("CARGO_PKG_VERSION"),
+        }
+    }
+
+    fn handle_home(&self) -> Response<Body> {
+        let page = html! {
+            <html>
+                <head>
+                    <title>"Rojo"</title>
+                    <style>
+                        { ritz::UnescapedText::new(HOME_CSS) }
+                    </style>
+                </head>
+
+                <body>
+                    <div class="main">
+                        <h1 class="title">
+                            "Rojo Live Sync is up and running!"
+                        </h1>
+                        <h2 class="subtitle">
+                            "Version " { self.server_version }
+                        </h2>
+                        <a class="docs" href="https://lpghatguy.github.io/rojo">
+                            "Rojo Documentation"
+                        </a>
+                    </div>
+                </body>
+            </html>
+        };
+
+        Response::builder()
+            .header(header::CONTENT_TYPE, "text/html")
+            .body(Body::from(format!("<!DOCTYPE html>{}", page)))
+            .unwrap()
+    }
+
+    fn handle_visualize_rbx(&self) -> Response<Body> {
+        let rbx_session = self.live_session.rbx_session.lock().unwrap();
+        let dot_source = format!("{}", VisualizeRbxSession(&rbx_session));
+
+        match graphviz_to_svg(&dot_source) {
+            Some(svg) => Response::builder()
+                .header(header::CONTENT_TYPE, "image/svg+xml")
+                .body(Body::from(svg))
+                .unwrap(),
+            None => Response::builder()
+                .header(header::CONTENT_TYPE, "text/plain")
+                .body(Body::from(dot_source))
+                .unwrap(),
+        }
+    }
+
+    fn handle_visualize_imfs(&self) -> Response<Body> {
+        let imfs = self.live_session.imfs.lock().unwrap();
+        let dot_source = format!("{}", VisualizeImfs(&imfs));
+
+        match graphviz_to_svg(&dot_source) {
+            Some(svg) => Response::builder()
+                .header(header::CONTENT_TYPE, "image/svg+xml")
+                .body(Body::from(svg))
+                .unwrap(),
+            None => Response::builder()
+                .header(header::CONTENT_TYPE, "text/plain")
+                .body(Body::from(dot_source))
+                .unwrap(),
+        }
+    }
+}

server/src/web/mod.rs

@@ -0,0 +1,85 @@
+// TODO: This module needs to be public for visualize, we should move
+// PublicInstanceMetadata and switch this private!
+pub mod api;
+mod interface;
+
+use std::sync::Arc;
+
+use log::trace;
+use futures::{
+    future::{self, FutureResult},
+    Future,
+};
+use hyper::{
+    service::Service,
+    Body,
+    Request,
+    Response,
+    Server,
+};
+
+use crate::{
+    live_session::LiveSession,
+};
+
+use self::{
+    api::ApiService,
+    interface::InterfaceService,
+};
+
+pub struct RootService {
+    api: api::ApiService,
+    interface: interface::InterfaceService,
+}
+
+impl Service for RootService {
+    type ReqBody = Body;
+    type ResBody = Body;
+    type Error = hyper::Error;
+    type Future = Box<dyn Future<Item = Response<Self::ReqBody>, Error = Self::Error> + Send>;
+
+    fn call(&mut self, request: Request<Self::ReqBody>) -> Self::Future {
+        trace!("{} {}", request.method(), request.uri().path());
+
+        if request.uri().path().starts_with("/api") {
+            self.api.call(request)
+        } else {
+            self.interface.call(request)
+        }
+    }
+}
+
+impl RootService {
+    pub fn new(live_session: Arc<LiveSession>) -> RootService {
+        RootService {
+            api: ApiService::new(Arc::clone(&live_session)),
+            interface: InterfaceService::new(Arc::clone(&live_session)),
+        }
+    }
+}
+
+pub struct LiveServer {
+    live_session: Arc<LiveSession>,
+}
+
+impl LiveServer {
+    pub fn new(live_session: Arc<LiveSession>) -> LiveServer {
+        LiveServer {
+            live_session,
+        }
+    }
+
+    pub fn start(self, port: u16) {
+        let address = ([127, 0, 0, 1], port).into();
+
+        let server = Server::bind(&address)
+            .serve(move || {
+                let service: FutureResult<_, hyper::Error> =
+                    future::ok(RootService::new(Arc::clone(&self.live_session)));
+                service
+            })
+            .map_err(|e| eprintln!("Server error: {}", e));
+
+        hyper::rt::run(server);
+    }
+}

server/src/web_util.rs

@@ -1,43 +0,0 @@
-use std::io::Read;
-
-use rouille;
-use serde;
-use serde_json;
-
-static MAX_BODY_SIZE: usize = 100 * 1024 * 1024; // 100 MiB
-
-/// Pulls text that may be JSON out of a Rouille Request object.
-///
-/// Doesn't do any actual parsing -- all this method does is verify the content
-/// type of the request and read the request's body.
-fn read_json_text(request: &rouille::Request) -> Option<String> {
-    // Bail out if the request body isn't marked as JSON
-    let content_type = request.header("Content-Type")?;
-
-    if !content_type.starts_with("application/json") {
-        return None;
-    }
-
-    let body = request.data()?;
-
-    // Allocate a buffer and read up to MAX_BODY_SIZE+1 bytes into it.
-    let mut out = Vec::new();
-    body.take(MAX_BODY_SIZE.saturating_add(1) as u64).read_to_end(&mut out).ok()?;
-
-    // If the body was too big (MAX_BODY_SIZE+1), we abort instead of trying to
-    // process it.
-    if out.len() > MAX_BODY_SIZE {
-        return None;
-    }
-
-    String::from_utf8(out).ok()
-}
-
-/// Reads the body out of a Rouille Request and attempts to turn it into JSON.
-pub fn read_json<T>(request: &rouille::Request) -> Option<T>
-where
-    T: serde::de::DeserializeOwned,
-{
-    let body = read_json_text(&request)?;
-    serde_json::from_str(&body).ok()?
-}

server/tests/imfs.rs

@@ -1,5 +1,5 @@
 use std::{
-    collections::{HashMap, HashSet},
+    collections::{HashMap, HashSet, BTreeSet},
     fs,
     path::PathBuf,
 };
@@ -80,7 +80,7 @@ fn base_tree() -> Result<(TempDir, Imfs, ExpectedImfs, TestResources), Error> {
     expected_roots.insert(root.path().to_path_buf());
 
     let root_item = {
-        let mut children = HashSet::new();
+        let mut children = BTreeSet::new();
         children.insert(foo_path.clone());
         children.insert(bar_path.clone());
 
@@ -91,7 +91,7 @@ fn base_tree() -> Result<(TempDir, Imfs, ExpectedImfs, TestResources), Error> {
     };
 
     let foo_item = {
-        let mut children = HashSet::new();
+        let mut children = BTreeSet::new();
         children.insert(baz_path.clone());
 
         ImfsItem::Directory(ImfsDirectory {
@@ -199,7 +199,7 @@ fn adding_folder() -> Result<(), Error> {
     }
 
     let folder_item = {
-        let mut children = HashSet::new();
+        let mut children = BTreeSet::new();
         children.insert(file1_path.clone());
         children.insert(file2_path.clone());
 

server/tests/read_projects.rs

@@ -1,12 +1,12 @@
 #[macro_use] extern crate lazy_static;
 
 use std::{
-    collections::HashMap,
+    collections::{HashMap, BTreeMap},
     path::{Path, PathBuf},
 };
 
 use pretty_assertions::assert_eq;
-use rbx_tree::RbxValue;
+use rbx_dom_weak::RbxValue;
 
 use librojo::{
     project::{Project, ProjectNode},
@@ -53,7 +53,7 @@ fn single_partition_game() {
             ..Default::default()
         };
 
-        let mut replicated_storage_children = HashMap::new();
+        let mut replicated_storage_children = BTreeMap::new();
         replicated_storage_children.insert("Foo".to_string(), foo);
 
         let replicated_storage = ProjectNode {
@@ -65,7 +65,7 @@ fn single_partition_game() {
         let mut http_service_properties = HashMap::new();
         http_service_properties.insert("HttpEnabled".to_string(), RbxValue::Bool {
             value: true,
-        });
+        }.into());
 
         let http_service = ProjectNode {
             class_name: Some(String::from("HttpService")),
@@ -73,7 +73,7 @@ fn single_partition_game() {
             ..Default::default()
         };
 
-        let mut root_children = HashMap::new();
+        let mut root_children = BTreeMap::new();
         root_children.insert("ReplicatedStorage".to_string(), replicated_storage);
         root_children.insert("HttpService".to_string(), http_service);
 
@@ -86,6 +86,7 @@ fn single_partition_game() {
         Project {
             name: "single-sync-point".to_string(),
             tree: root_node,
+            plugins: Vec::new(),
             serve_port: None,
             serve_place_ids: None,
             file_location: project_location.join("default.project.json"),

server/tests/snapshot_reconciler.rs

@@ -0,0 +1,112 @@
+mod test_util;
+
+use std::collections::HashMap;
+
+use pretty_assertions::assert_eq;
+use rbx_dom_weak::{RbxTree, RbxInstanceProperties};
+
+use librojo::{
+    snapshot_reconciler::{RbxSnapshotInstance, reconcile_subtree},
+};
+
+use test_util::tree::trees_equal;
+
+#[test]
+fn patch_communicativity() {
+    let base_tree = RbxTree::new(RbxInstanceProperties {
+        name: "DataModel".into(),
+        class_name: "DataModel".into(),
+        properties: HashMap::new(),
+    });
+
+    let patch_a = RbxSnapshotInstance {
+        name: "DataModel".into(),
+        class_name: "DataModel".into(),
+        children: vec![
+            RbxSnapshotInstance {
+                name: "Child-A".into(),
+                class_name: "Folder".into(),
+                ..Default::default()
+            },
+        ],
+        ..Default::default()
+    };
+
+    let patch_b = RbxSnapshotInstance {
+        name: "DataModel".into(),
+        class_name: "DataModel".into(),
+        children: vec![
+            RbxSnapshotInstance {
+                name: "Child-B".into(),
+                class_name: "Folder".into(),
+                ..Default::default()
+            },
+        ],
+        ..Default::default()
+    };
+
+    let patch_combined = RbxSnapshotInstance {
+        name: "DataModel".into(),
+        class_name: "DataModel".into(),
+        children: vec![
+            RbxSnapshotInstance {
+                name: "Child-A".into(),
+                class_name: "Folder".into(),
+                ..Default::default()
+            },
+            RbxSnapshotInstance {
+                name: "Child-B".into(),
+                class_name: "Folder".into(),
+                ..Default::default()
+            },
+        ],
+        ..Default::default()
+    };
+
+    let root_id = base_tree.get_root_id();
+
+    let mut tree_a = base_tree.clone();
+
+    reconcile_subtree(
+        &mut tree_a,
+        root_id,
+        &patch_a,
+        &mut Default::default(),
+        &mut Default::default(),
+        &mut Default::default(),
+    );
+
+    reconcile_subtree(
+        &mut tree_a,
+        root_id,
+        &patch_combined,
+        &mut Default::default(),
+        &mut Default::default(),
+        &mut Default::default(),
+    );
+
+    let mut tree_b = base_tree.clone();
+
+    reconcile_subtree(
+        &mut tree_b,
+        root_id,
+        &patch_b,
+        &mut Default::default(),
+        &mut Default::default(),
+        &mut Default::default(),
+    );
+
+    reconcile_subtree(
+        &mut tree_b,
+        root_id,
+        &patch_combined,
+        &mut Default::default(),
+        &mut Default::default(),
+        &mut Default::default(),
+    );
+
+    match trees_equal(&tree_a, &tree_b) {
+        Ok(_) => {}
+        Err(e) => panic!("{}", e),
+    }
+}

server/tests/snapshot_snapshots.rs

@@ -0,0 +1,69 @@
+mod test_util;
+
+use std::path::Path;
+
+use pretty_assertions::assert_eq;
+
+use librojo::{
+    imfs::Imfs,
+    project::Project,
+    rbx_snapshot::{SnapshotContext, snapshot_project_tree},
+};
+
+use crate::test_util::{
+    snapshot::*,
+};
+
+macro_rules! generate_snapshot_tests {
+    ($($name: ident),*) => {
+        $(
+            paste::item! {
+                #[test]
+                fn [<snapshot_ $name>]() {
+                    let _ = env_logger::try_init();
+
+                    let tests_folder = Path::new(env!("CARGO_MANIFEST_DIR")).join("../test-projects");
+                    let project_folder = tests_folder.join(stringify!($name));
+                    run_snapshot_test(&project_folder);
+                }
+            }
+        )*
+    };
+}
+
+generate_snapshot_tests!(
+    empty,
+    localization,
+    multi_partition_game,
+    nested_partitions,
+    single_partition_game,
+    single_partition_model,
+    transmute_partition
+);
+
+fn run_snapshot_test(path: &Path) {
+    println!("Running snapshot from project: {}", path.display());
+
+    let project = Project::load_fuzzy(path)
+        .expect("Couldn't load project file for snapshot test");
+
+    let mut imfs = Imfs::new();
+    imfs.add_roots_from_project(&project)
+        .expect("Could not add IMFS roots to snapshot project");
+
+    let context = SnapshotContext {
+        plugin_context: None,
+    };
+
+    let mut snapshot = snapshot_project_tree(&context, &imfs, &project)
+        .expect("Could not generate snapshot for snapshot test");
+
+    if let Some(snapshot) = snapshot.as_mut() {
+        anonymize_snapshot(path, snapshot);
+    }
+
+    match read_expected_snapshot(path) {
+        Some(expected_snapshot) => assert_eq!(snapshot, expected_snapshot),
+        None => write_expected_snapshot(path, &snapshot),
+    }
+}

server/tests/snapshots.rs

@@ -1,124 +0,0 @@
-use std::{
-    fs::{self, File},
-    path::{Path, PathBuf},
-};
-
-use pretty_assertions::assert_eq;
-
-use librojo::{
-    imfs::Imfs,
-    project::{Project, ProjectNode},
-    rbx_snapshot::snapshot_project_tree,
-    snapshot_reconciler::{RbxSnapshotInstance},
-};
-
-macro_rules! generate_snapshot_tests {
-    ($($name: ident),*) => {
-        $(
-            paste::item! {
-                #[test]
-                fn [<snapshot_ $name>]() {
-                    let tests_folder = Path::new(env!("CARGO_MANIFEST_DIR")).join("../test-projects");
-                    let project_folder = tests_folder.join(stringify!($name));
-                    run_snapshot_test(&project_folder);
-                }
-            }
-        )*
-    };
-}
-
-generate_snapshot_tests!(
-    empty,
-    nested_partitions,
-    single_partition_game,
-    single_partition_model,
-    transmute_partition
-);
-
-const SNAPSHOT_EXPECTED_NAME: &str = "expected-snapshot.json";
-
-fn run_snapshot_test(path: &Path) {
-    println!("Running snapshot from project: {}", path.display());
-
-    let project = Project::load_fuzzy(path)
-        .expect("Couldn't load project file for snapshot test");
-
-    let mut imfs = Imfs::new();
-    imfs.add_roots_from_project(&project)
-        .expect("Could not add IMFS roots to snapshot project");
-
-    let mut snapshot = snapshot_project_tree(&imfs, &project)
-        .expect("Could not generate snapshot for snapshot test");
-
-    if let Some(snapshot) = snapshot.as_mut() {
-        anonymize_snapshot(path, snapshot);
-    }
-
-    match read_expected_snapshot(path) {
-        Some(expected_snapshot) => assert_eq!(snapshot, expected_snapshot),
-        None => write_expected_snapshot(path, &snapshot),
-    }
-}
-
-/// Snapshots contain absolute paths, which simplifies much of Rojo.
-///
-/// For saving snapshots to the disk, we should strip off the project folder
-/// path to make them machine-independent. This doesn't work for paths that fall
-/// outside of the project folder, but that's okay here.
-///
-/// We also need to sort children, since Rojo tends to enumerate the filesystem
-/// in an unpredictable order.
-fn anonymize_snapshot(project_folder_path: &Path, snapshot: &mut RbxSnapshotInstance) {
-    match snapshot.metadata.source_path.as_mut() {
-        Some(path) => *path = anonymize_path(project_folder_path, path),
-        None => {},
-    }
-
-    match snapshot.metadata.project_definition.as_mut() {
-        Some((_, project_node)) => anonymize_project_node(project_folder_path, project_node),
-        None => {},
-    }
-
-    snapshot.children.sort_by(|a, b| a.partial_cmp(b).unwrap());
-
-    for child in snapshot.children.iter_mut() {
-        anonymize_snapshot(project_folder_path, child);
-    }
-}
-
-fn anonymize_project_node(project_folder_path: &Path, project_node: &mut ProjectNode) {
-    match project_node.path.as_mut() {
-        Some(path) => *path = anonymize_path(project_folder_path, path),
-        None => {},
-    }
-
-    for child_node in project_node.children.values_mut() {
-        anonymize_project_node(project_folder_path, child_node);
-    }
-}
-
-fn anonymize_path(project_folder_path: &Path, path: &Path) -> PathBuf {
-    if path.is_absolute() {
-        path.strip_prefix(project_folder_path)
-            .expect("Could not anonymize absolute path")
-            .to_path_buf()
-    } else {
-        path.to_path_buf()
-    }
-}
-
-fn read_expected_snapshot(path: &Path) -> Option<Option<RbxSnapshotInstance<'static>>> {
-    let contents = fs::read(path.join(SNAPSHOT_EXPECTED_NAME)).ok()?;
-    let snapshot: Option<RbxSnapshotInstance<'static>> = serde_json::from_slice(&contents)
-        .expect("Could not deserialize snapshot");
-
-    Some(snapshot)
-}
-
-fn write_expected_snapshot(path: &Path, snapshot: &Option<RbxSnapshotInstance>) {
-    let mut file = File::create(path.join(SNAPSHOT_EXPECTED_NAME))
-        .expect("Could not open file to write snapshot");
-
-    serde_json::to_writer_pretty(&mut file, snapshot)
-        .expect("Could not serialize snapshot to file");
-}

server/tests/test_util/mod.rs

@@ -1,31 +1,13 @@
+#![allow(dead_code)]
+
 use std::fs::{create_dir, copy};
 use std::path::Path;
 use std::io;
 
-use rouille::Request;
-
 use walkdir::WalkDir;
 
-use librojo::web::Server;
-
-pub trait HttpTestUtil {
-    fn get_string(&self, url: &str) -> String;
-}
-
-impl HttpTestUtil for Server {
-    fn get_string(&self, url: &str) -> String {
-        let info_request = Request::fake_http("GET", url, vec![], vec![]);
-        let response = self.handle_request(&info_request);
-
-        assert_eq!(response.status_code, 200);
-
-        let (mut reader, _) = response.data.into_reader_and_size();
-        let mut body = String::new();
-        reader.read_to_string(&mut body).unwrap();
-
-        body
-    }
-}
+pub mod snapshot;
+pub mod tree;
 
 pub fn copy_recursive(from: &Path, to: &Path) -> io::Result<()> {
     for entry in WalkDir::new(from) {
@@ -51,4 +33,4 @@ pub fn copy_recursive(from: &Path, to: &Path) -> io::Result<()> {
     }
 
     Ok(())
-}
+}

server/tests/test_util/snapshot.rs

@@ -0,0 +1,79 @@
+use std::{
+    fs::{self, File},
+    path::{Path, PathBuf},
+};
+
+use librojo::{
+    project::ProjectNode,
+    snapshot_reconciler::RbxSnapshotInstance,
+    rbx_session::MetadataPerInstance,
+};
+
+const SNAPSHOT_EXPECTED_NAME: &str = "expected-snapshot.json";
+
+/// Snapshots contain absolute paths, which simplifies much of Rojo.
+///
+/// For saving snapshots to the disk, we should strip off the project folder
+/// path to make them machine-independent. This doesn't work for paths that fall
+/// outside of the project folder, but that's okay here.
+///
+/// We also need to sort children, since Rojo tends to enumerate the filesystem
+/// in an unpredictable order.
+pub fn anonymize_snapshot(project_folder_path: &Path, snapshot: &mut RbxSnapshotInstance) {
+    anonymize_metadata(project_folder_path, &mut snapshot.metadata);
+
+    snapshot.children.sort_by(|a, b| a.partial_cmp(b).unwrap());
+
+    for child in snapshot.children.iter_mut() {
+        anonymize_snapshot(project_folder_path, child);
+    }
+}
+
+pub fn anonymize_metadata(project_folder_path: &Path, metadata: &mut MetadataPerInstance) {
+    match metadata.source_path.as_mut() {
+        Some(path) => *path = anonymize_path(project_folder_path, path),
+        None => {},
+    }
+
+    match metadata.project_definition.as_mut() {
+        Some((_, project_node)) => anonymize_project_node(project_folder_path, project_node),
+        None => {},
+    }
+}
+
+pub fn anonymize_project_node(project_folder_path: &Path, project_node: &mut ProjectNode) {
+    match project_node.path.as_mut() {
+        Some(path) => *path = anonymize_path(project_folder_path, path),
+        None => {},
+    }
+
+    for child_node in project_node.children.values_mut() {
+        anonymize_project_node(project_folder_path, child_node);
+    }
+}
+
+pub fn anonymize_path(project_folder_path: &Path, path: &Path) -> PathBuf {
+    if path.is_absolute() {
+        path.strip_prefix(project_folder_path)
+            .expect("Could not anonymize absolute path")
+            .to_path_buf()
+    } else {
+        path.to_path_buf()
+    }
+}
+
+pub fn read_expected_snapshot(path: &Path) -> Option<Option<RbxSnapshotInstance<'static>>> {
+    let contents = fs::read(path.join(SNAPSHOT_EXPECTED_NAME)).ok()?;
+    let snapshot: Option<RbxSnapshotInstance<'static>> = serde_json::from_slice(&contents)
+        .expect("Could not deserialize snapshot");
+
+    Some(snapshot)
+}
+
+pub fn write_expected_snapshot(path: &Path, snapshot: &Option<RbxSnapshotInstance>) {
+    let mut file = File::create(path.join(SNAPSHOT_EXPECTED_NAME))
+        .expect("Could not open file to write snapshot");
+
+    serde_json::to_writer_pretty(&mut file, snapshot)
+        .expect("Could not serialize snapshot to file");
+}

server/tests/test_util/tree.rs

@@ -0,0 +1,351 @@
+//! Defines a mechanism to compare two RbxTree objects and generate a useful
+//! diff if they aren't the same. These methods ignore IDs, which are randomly
+//! generated whenever a tree is constructed anyways. This makes matching up
+//! pairs of instances that should be the same potentially difficult.
+//!
+//! It relies on a couple different ideas:
+//! - Instances with the same name and class name are matched as the same
+//!   instance. See basic_equal for this logic
+//! - A path of period-delimited names (like Roblox's GetFullName) should be
+//!   enough to debug most issues. If it isn't, we can do something fun like
+//!   generate GraphViz graphs.
+
+use std::{
+    borrow::Cow,
+    collections::{HashMap, HashSet},
+    fmt,
+    fs::{self, File},
+    hash::Hash,
+    path::{Path, PathBuf},
+};
+
+use log::error;
+use serde_derive::{Serialize, Deserialize};
+use rbx_dom_weak::{RbxId, RbxTree};
+
+use librojo::{
+    rbx_session::MetadataPerInstance,
+    live_session::LiveSession,
+    visualize::{VisualizeRbxTree, graphviz_to_svg},
+};
+
+use super::snapshot::anonymize_metadata;
+
+/// Marks a 'step' in the test, which will snapshot the session's current
+/// RbxTree object and compare it against the saved snapshot if it exists.
+pub fn tree_step(step: &str, live_session: &LiveSession, source_path: &Path) {
+    let rbx_session = live_session.rbx_session.lock().unwrap();
+    let tree = rbx_session.get_tree();
+
+    let project_folder = live_session.root_project().folder_location();
+    let metadata = rbx_session.get_all_instance_metadata()
+        .iter()
+        .map(|(key, meta)| {
+            let mut meta = meta.clone();
+            anonymize_metadata(project_folder, &mut meta);
+            (*key, meta)
+        })
+        .collect();
+
+    let tree_with_metadata = TreeWithMetadata {
+        tree: Cow::Borrowed(&tree),
+        metadata: Cow::Owned(metadata),
+    };
+
+    match read_tree_by_name(source_path, step) {
+        Some(expected) => match trees_and_metadata_equal(&expected, &tree_with_metadata) {
+            Ok(_) => {}
+            Err(e) => {
+                error!("Trees at step '{}' were not equal.\n{}", step, e);
+
+                let expected_gv = format!("{}", VisualizeRbxTree {
+                    tree: &expected.tree,
+                    metadata: &expected.metadata,
+                });
+
+                let actual_gv = format!("{}", VisualizeRbxTree {
+                    tree: &tree_with_metadata.tree,
+                    metadata: &tree_with_metadata.metadata,
+                });
+
+                let output_dir = PathBuf::from("failed-snapshots");
+                fs::create_dir_all(&output_dir)
+                    .expect("Could not create failed-snapshots directory");
+
+                let expected_basename = format!("{}-{}-expected", live_session.root_project().name, step);
+                let actual_basename = format!("{}-{}-actual", live_session.root_project().name, step);
+
+                let mut expected_out = output_dir.join(expected_basename);
+                let mut actual_out = output_dir.join(actual_basename);
+
+                match (graphviz_to_svg(&expected_gv), graphviz_to_svg(&actual_gv)) {
+                    (Some(expected_svg), Some(actual_svg)) => {
+                        expected_out.set_extension("svg");
+                        actual_out.set_extension("svg");
+
+                        fs::write(&expected_out, expected_svg)
+                            .expect("Couldn't write expected SVG");
+
+                        fs::write(&actual_out, actual_svg)
+                            .expect("Couldn't write actual SVG");
+                    }
+                    _ => {
+                        expected_out.set_extension("gv");
+                        actual_out.set_extension("gv");
+
+                        fs::write(&expected_out, expected_gv)
+                            .expect("Couldn't write expected GV");
+
+                        fs::write(&actual_out, actual_gv)
+                            .expect("Couldn't write actual GV");
+                    }
+                }
+
+                error!("Output at {} and {}", expected_out.display(), actual_out.display());
+
+                panic!("Tree mismatch at step '{}'", step);
+            }
+        }
+        None => {
+            write_tree_by_name(source_path, step, &tree_with_metadata);
+        }
+    }
+}
+
+fn new_cow_map<K: Clone + Eq + Hash, V: Clone>() -> Cow<'static, HashMap<K, V>> {
+    Cow::Owned(HashMap::new())
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+struct TreeWithMetadata<'a> {
+    #[serde(flatten)]
+    pub tree: Cow<'a, RbxTree>,
+
+    #[serde(default = "new_cow_map")]
+    pub metadata: Cow<'a, HashMap<RbxId, MetadataPerInstance>>,
+}
+
+fn read_tree_by_name(path: &Path, identifier: &str) -> Option<TreeWithMetadata<'static>> {
+    let mut file_path = path.join(identifier);
+    file_path.set_extension("tree.json");
+
+    let contents = fs::read(&file_path).ok()?;
+    let tree: TreeWithMetadata = serde_json::from_slice(&contents)
+        .expect("Could not deserialize tree");
+
+    Some(tree)
+}
+
+fn write_tree_by_name(path: &Path, identifier: &str, tree: &TreeWithMetadata) {
+    let mut file_path = path.join(identifier);
+    file_path.set_extension("tree.json");
+
+    let mut file = File::create(file_path)
+        .expect("Could not open file to write tree");
+
+    serde_json::to_writer_pretty(&mut file, tree)
+        .expect("Could not serialize tree to file");
+}
+
+#[derive(Debug)]
+pub struct TreeMismatch {
+    pub path: Cow<'static, str>,
+    pub detail: Cow<'static, str>,
+}
+
+impl TreeMismatch {
+    pub fn new<'a, A: Into<Cow<'a, str>>, B: Into<Cow<'a, str>>>(path: A, detail: B) -> TreeMismatch {
+        TreeMismatch {
+            path: Cow::Owned(path.into().into_owned()),
+            detail: Cow::Owned(detail.into().into_owned()),
+        }
+    }
+
+    fn add_parent(mut self, name: &str) -> TreeMismatch {
+        self.path.to_mut().insert(0, '.');
+        self.path.to_mut().insert_str(0, name);
+
+        TreeMismatch {
+            path: self.path,
+            detail: self.detail,
+        }
+    }
+}
+
+impl fmt::Display for TreeMismatch {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        writeln!(formatter, "Tree mismatch at path {}", self.path)?;
+        writeln!(formatter, "{}", self.detail)
+    }
+}
+
+pub fn trees_equal(
+    left_tree: &RbxTree,
+    right_tree: &RbxTree,
+) -> Result<(), TreeMismatch> {
+    let left = TreeWithMetadata {
+        tree: Cow::Borrowed(left_tree),
+        metadata: Cow::Owned(HashMap::new()),
+    };
+
+    let right = TreeWithMetadata {
+        tree: Cow::Borrowed(right_tree),
+        metadata: Cow::Owned(HashMap::new()),
+    };
+
+    trees_and_metadata_equal(&left, &right)
+}
+
+fn trees_and_metadata_equal(
+    left_tree: &TreeWithMetadata,
+    right_tree: &TreeWithMetadata,
+) -> Result<(), TreeMismatch> {
+    let left_id = left_tree.tree.get_root_id();
+    let right_id = right_tree.tree.get_root_id();
+
+    instances_equal(left_tree, left_id, right_tree, right_id)
+}
+
+fn instances_equal(
+    left_tree: &TreeWithMetadata,
+    left_id: RbxId,
+    right_tree: &TreeWithMetadata,
+    right_id: RbxId,
+) -> Result<(), TreeMismatch> {
+    basic_equal(left_tree, left_id, right_tree, right_id)?;
+    properties_equal(left_tree, left_id, right_tree, right_id)?;
+    children_equal(left_tree, left_id, right_tree, right_id)?;
+    metadata_equal(left_tree, left_id, right_tree, right_id)
+}
+
+fn basic_equal(
+    left_tree: &TreeWithMetadata,
+    left_id: RbxId,
+    right_tree: &TreeWithMetadata,
+    right_id: RbxId,
+) -> Result<(), TreeMismatch> {
+    let left_instance = left_tree.tree.get_instance(left_id)
+        .expect("ID did not exist in left tree");
+
+    let right_instance = right_tree.tree.get_instance(right_id)
+        .expect("ID did not exist in right tree");
+
+    if left_instance.name != right_instance.name {
+        let message = format!("Name did not match ('{}' vs '{}')", left_instance.name, right_instance.name);
+
+        return Err(TreeMismatch::new(&left_instance.name, message));
+    }
+
+    if left_instance.class_name != right_instance.class_name {
+        let message = format!("Class name did not match ('{}' vs '{}')", left_instance.class_name, right_instance.class_name);
+
+        return Err(TreeMismatch::new(&left_instance.name, message));
+    }
+
+    Ok(())
+}
+
+fn properties_equal(
+    left_tree: &TreeWithMetadata,
+    left_id: RbxId,
+    right_tree: &TreeWithMetadata,
+    right_id: RbxId,
+) -> Result<(), TreeMismatch> {
+    let left_instance = left_tree.tree.get_instance(left_id)
+        .expect("ID did not exist in left tree");
+
+    let right_instance = right_tree.tree.get_instance(right_id)
+        .expect("ID did not exist in right tree");
+
+    let mut visited = HashSet::new();
+
+    for (key, left_value) in &left_instance.properties {
+        visited.insert(key);
+
+        let right_value = right_instance.properties.get(key);
+
+        if Some(left_value) != right_value {
+            let message = format!(
+                "Property {}:\n\tLeft: {:?}\n\tRight: {:?}",
+                key,
+                Some(left_value),
+                right_value,
+            );
+
+            return Err(TreeMismatch::new(&left_instance.name, message));
+        }
+    }
+
+    for (key, right_value) in &right_instance.properties {
+        if visited.contains(key) {
+            continue;
+        }
+
+        let left_value = left_instance.properties.get(key);
+
+        if left_value != Some(right_value) {
+            let message = format!(
+                "Property {}:\n\tLeft: {:?}\n\tRight: {:?}",
+                key,
+                left_value,
+                Some(right_value),
+            );
+
+            return Err(TreeMismatch::new(&left_instance.name, message));
+        }
+    }
+
+    Ok(())
+}
+
+fn children_equal(
+    left_tree: &TreeWithMetadata,
+    left_id: RbxId,
+    right_tree: &TreeWithMetadata,
+    right_id: RbxId,
+) -> Result<(), TreeMismatch> {
+    let left_instance = left_tree.tree.get_instance(left_id)
+        .expect("ID did not exist in left tree");
+
+    let right_instance = right_tree.tree.get_instance(right_id)
+        .expect("ID did not exist in right tree");
+
+    let left_children = left_instance.get_children_ids();
+    let right_children = right_instance.get_children_ids();
+
+    if left_children.len() != right_children.len() {
+        return Err(TreeMismatch::new(&left_instance.name, "Instances had different numbers of children"));
+    }
+
+    for (left_child_id, right_child_id) in left_children.iter().zip(right_children) {
+        instances_equal(left_tree, *left_child_id, right_tree, *right_child_id)
+            .map_err(|e| e.add_parent(&left_instance.name))?;
+    }
+
+    Ok(())
+}
+
+fn metadata_equal(
+    left_tree: &TreeWithMetadata,
+    left_id: RbxId,
+    right_tree: &TreeWithMetadata,
+    right_id: RbxId,
+) -> Result<(), TreeMismatch> {
+    let left_meta = left_tree.metadata.get(&left_id);
+    let right_meta = right_tree.metadata.get(&right_id);
+
+    if left_meta != right_meta {
+        let left_instance = left_tree.tree.get_instance(left_id)
+            .expect("Left instance didn't exist in tree");
+
+        let message = format!(
+            "Metadata mismatch:\n\tLeft: {:?}\n\tRight: {:?}",
+            left_meta,
+            right_meta,
+        );
+
+        return Err(TreeMismatch::new(&left_instance.name, message));
+    }
+
+    Ok(())
+}

server/tests/tree_snapshots.rs

@@ -0,0 +1,68 @@
+mod test_util;
+
+use std::{
+    fs,
+    path::{Path, PathBuf},
+    sync::Arc,
+    thread,
+    time::Duration,
+};
+
+use tempfile::{tempdir, TempDir};
+
+use librojo::{
+    live_session::LiveSession,
+    project::Project,
+};
+
+use crate::test_util::{
+    copy_recursive,
+    tree::tree_step,
+};
+
+#[test]
+fn multi_partition_game() {
+    let _ = env_logger::try_init();
+    let source_path = project_path("multi_partition_game");
+
+    let (dir, live_session) = start_session(&source_path);
+    tree_step("initial", &live_session, &source_path);
+
+    let added_path = dir.path().join("a/added");
+    fs::create_dir_all(&added_path)
+        .expect("Couldn't create directory");
+    thread::sleep(Duration::from_millis(250));
+
+    tree_step("with_dir", &live_session, &source_path);
+
+    let moved_path = dir.path().join("b/added");
+    fs::rename(&added_path, &moved_path)
+        .expect("Couldn't rename directory");
+    thread::sleep(Duration::from_millis(250));
+
+    tree_step("with_moved_dir", &live_session, &source_path);
+}
+
+/// Find the path to the given test project relative to the manifest.
+fn project_path(name: &str) -> PathBuf {
+    let mut path = Path::new(env!("CARGO_MANIFEST_DIR")).join("../test-projects");
+    path.push(name);
+    path
+}
+
+/// Starts a new LiveSession for the project located at the given file path.
+fn start_session(source_path: &Path) -> (TempDir, LiveSession) {
+    let dir = tempdir()
+        .expect("Couldn't create temporary directory");
+
+    copy_recursive(&source_path, dir.path())
+        .expect("Couldn't copy project to temporary directory");
+
+    let project = Arc::new(Project::load_fuzzy(dir.path())
+        .expect("Couldn't load project from temp directory"));
+
+    let live_session = LiveSession::new(Arc::clone(&project))
+        .expect("Couldn't start live session");
+
+    (dir, live_session)
+}

test-projects/localization/default.project.json

@@ -0,0 +1,6 @@
+{
+  "name": "localization",
+  "tree": {
+    "$path": "src"
+  }
+}

test-projects/localization/expected-snapshot.json

@@ -0,0 +1,69 @@
+{
+  "name": "localization",
+  "class_name": "Folder",
+  "properties": {},
+  "children": [
+    {
+      "name": "empty-column-bug-147",
+      "class_name": "LocalizationTable",
+      "properties": {
+        "Contents": {
+          "Type": "String",
+          "Value": "[{\"key\":\"Language.Name\",\"source\":\"English\",\"values\":{}},{\"key\":\"Language.Region\",\"source\":\"United States\",\"values\":{}},{\"key\":\"Label.Thickness\",\"source\":\"Thickness\",\"values\":{}},{\"key\":\"Label.Opacity\",\"source\":\"Opacity\",\"values\":{}},{\"key\":\"Toolbar.Undo\",\"source\":\"Undo\",\"values\":{}},{\"key\":\"Toolbar.Redo\",\"source\":\"Redo\",\"values\":{}},{\"key\":\"Toolbar.Camera\",\"source\":\"Top-down camera\",\"values\":{}},{\"key\":\"Toolbar.Saves\",\"source\":\"Saved drawings\",\"values\":{}},{\"key\":\"Toolbar.Preferences\",\"source\":\"Settings\",\"values\":{}},{\"key\":\"Toolbar.Mode.Vector\",\"source\":\"Vector mode\",\"values\":{}},{\"key\":\"Toolbar.Mode.Pixel\",\"source\":\"Pixel mode\",\"values\":{}}]"
+        }
+      },
+      "children": [],
+      "metadata": {
+        "ignore_unknown_instances": false,
+        "source_path": "src/empty-column-bug-147.csv",
+        "project_definition": null
+      }
+    },
+    {
+      "name": "integers-bug-145",
+      "class_name": "LocalizationTable",
+      "properties": {
+        "Contents": {
+          "Type": "String",
+          "Value": "[{\"key\":\"Count\",\"example\":\"A number demonstrating issue 145\",\"source\":\"3\",\"values\":{\"es\":\"7\"}}]"
+        }
+      },
+      "children": [],
+      "metadata": {
+        "ignore_unknown_instances": false,
+        "source_path": "src/integers-bug-145.csv",
+        "project_definition": null
+      }
+    },
+    {
+      "name": "normal",
+      "class_name": "LocalizationTable",
+      "properties": {
+        "Contents": {
+          "Type": "String",
+          "Value": "[{\"key\":\"Ack\",\"example\":\"An exclamation of despair\",\"source\":\"Ack!\",\"values\":{\"es\":\"¡Ay!\"}}]"
+        }
+      },
+      "children": [],
+      "metadata": {
+        "ignore_unknown_instances": false,
+        "source_path": "src/normal.csv",
+        "project_definition": null
+      }
+    }
+  ],
+  "metadata": {
+    "ignore_unknown_instances": false,
+    "source_path": "src",
+    "project_definition": [
+      "localization",
+      {
+        "class_name": null,
+        "children": {},
+        "properties": {},
+        "ignore_unknown_instances": null,
+        "path": "src"
+      }
+    ]
+  }
+}

test-projects/localization/src/empty-column-bug-147.csv

@@ -0,0 +1,17 @@
+,Key,Source,Context,Example
+,,,,
+Metadata,Language.Name,English,,
+,Language.Region,United States,,
+,,,,
+Options,Label.Thickness,Thickness,,
+,Label.Opacity,Opacity,,
+,,,,
+Toolbar,Toolbar.Undo,Undo,,
+,Toolbar.Redo,Redo,,
+,,,,
+,Toolbar.Camera,Top-down camera,,
+,Toolbar.Saves,Saved drawings,,
+,Toolbar.Preferences,Settings,,
+,,,,
+,Toolbar.Mode.Vector,Vector mode,,
+,Toolbar.Mode.Pixel,Pixel mode,,

test-projects/localization/src/integers-bug-145.csv

@@ -0,0 +1,2 @@
+Key,Source,Context,Example,es
+Count,3,,A number demonstrating issue 145,7

test-projects/localization/src/normal.csv

@@ -0,0 +1,2 @@
+Key,Source,Context,Example,es
+Ack,Ack!,,An exclamation of despair,¡Ay!

test-projects/malformed-stuff/default.project.json

@@ -0,0 +1,6 @@
+{
+  "name": "malformed-stuff",
+  "tree": {
+    "$path": "src"
+  }
+}

test-projects/malformed-stuff/src/bad-model.model.json

@@ -0,0 +1,2 @@
+ahhh this isn't a JSON model
+bamboozled again

test-projects/multi_partition_game/a/foo.txt

@@ -0,0 +1 @@
+Hello world, from a/foo.txt

test-projects/multi_partition_game/a/main.lua

@@ -0,0 +1 @@
+-- hello, from a/main.lua

test-projects/multi_partition_game/b/something.lua

@@ -0,0 +1 @@
+-- b/something.lua

test-projects/multi_partition_game/default.project.json

@@ -0,0 +1,21 @@
+{
+  "name": "multi_partition_game",
+  "tree": {
+    "$className": "DataModel",
+    "ReplicatedStorage": {
+      "$className": "ReplicatedStorage",
+      "Ack": {
+        "$path": "a"
+      },
+      "Bar": {
+        "$path": "b"
+      }
+    },
+    "HttpService": {
+      "$className": "HttpService",
+      "$properties": {
+        "HttpEnabled": true
+      }
+    }
+  }
+}

test-projects/multi_partition_game/expected-snapshot.json

@@ -0,0 +1,212 @@
+{
+  "name": "multi_partition_game",
+  "class_name": "DataModel",
+  "properties": {},
+  "children": [
+    {
+      "name": "HttpService",
+      "class_name": "HttpService",
+      "properties": {
+        "HttpEnabled": {
+          "Type": "Bool",
+          "Value": true
+        }
+      },
+      "children": [],
+      "metadata": {
+        "ignore_unknown_instances": true,
+        "source_path": null,
+        "project_definition": [
+          "HttpService",
+          {
+            "class_name": "HttpService",
+            "children": {},
+            "properties": {
+              "HttpEnabled": {
+                "Type": "Bool",
+                "Value": true
+              }
+            },
+            "ignore_unknown_instances": null,
+            "path": null
+          }
+        ]
+      }
+    },
+    {
+      "name": "ReplicatedStorage",
+      "class_name": "ReplicatedStorage",
+      "properties": {},
+      "children": [
+        {
+          "name": "Ack",
+          "class_name": "Folder",
+          "properties": {},
+          "children": [
+            {
+              "name": "foo",
+              "class_name": "StringValue",
+              "properties": {
+                "Value": {
+                  "Type": "String",
+                  "Value": "Hello world, from a/foo.txt"
+                }
+              },
+              "children": [],
+              "metadata": {
+                "ignore_unknown_instances": false,
+                "source_path": "a/foo.txt",
+                "project_definition": null
+              }
+            },
+            {
+              "name": "main",
+              "class_name": "ModuleScript",
+              "properties": {
+                "Source": {
+                  "Type": "String",
+                  "Value": "-- hello, from a/main.lua"
+                }
+              },
+              "children": [],
+              "metadata": {
+                "ignore_unknown_instances": false,
+                "source_path": "a/main.lua",
+                "project_definition": null
+              }
+            }
+          ],
+          "metadata": {
+            "ignore_unknown_instances": false,
+            "source_path": "a",
+            "project_definition": [
+              "Ack",
+              {
+                "class_name": null,
+                "children": {},
+                "properties": {},
+                "ignore_unknown_instances": null,
+                "path": "a"
+              }
+            ]
+          }
+        },
+        {
+          "name": "Bar",
+          "class_name": "Folder",
+          "properties": {},
+          "children": [
+            {
+              "name": "something",
+              "class_name": "ModuleScript",
+              "properties": {
+                "Source": {
+                  "Type": "String",
+                  "Value": "-- b/something.lua"
+                }
+              },
+              "children": [],
+              "metadata": {
+                "ignore_unknown_instances": false,
+                "source_path": "b/something.lua",
+                "project_definition": null
+              }
+            }
+          ],
+          "metadata": {
+            "ignore_unknown_instances": false,
+            "source_path": "b",
+            "project_definition": [
+              "Bar",
+              {
+                "class_name": null,
+                "children": {},
+                "properties": {},
+                "ignore_unknown_instances": null,
+                "path": "b"
+              }
+            ]
+          }
+        }
+      ],
+      "metadata": {
+        "ignore_unknown_instances": true,
+        "source_path": null,
+        "project_definition": [
+          "ReplicatedStorage",
+          {
+            "class_name": "ReplicatedStorage",
+            "children": {
+              "Bar": {
+                "class_name": null,
+                "children": {},
+                "properties": {},
+                "ignore_unknown_instances": null,
+                "path": "b"
+              },
+              "Ack": {
+                "class_name": null,
+                "children": {},
+                "properties": {},
+                "ignore_unknown_instances": null,
+                "path": "a"
+              }
+            },
+            "properties": {},
+            "ignore_unknown_instances": null,
+            "path": null
+          }
+        ]
+      }
+    }
+  ],
+  "metadata": {
+    "ignore_unknown_instances": true,
+    "source_path": null,
+    "project_definition": [
+      "multi_partition_game",
+      {
+        "class_name": "DataModel",
+        "children": {
+          "ReplicatedStorage": {
+            "class_name": "ReplicatedStorage",
+            "children": {
+              "Bar": {
+                "class_name": null,
+                "children": {},
+                "properties": {},
+                "ignore_unknown_instances": null,
+                "path": "b"
+              },
+              "Ack": {
+                "class_name": null,
+                "children": {},
+                "properties": {},
+                "ignore_unknown_instances": null,
+                "path": "a"
+              }
+            },
+            "properties": {},
+            "ignore_unknown_instances": null,
+            "path": null
+          },
+          "HttpService": {
+            "class_name": "HttpService",
+            "children": {},
+            "properties": {
+              "HttpEnabled": {
+                "Type": "Bool",
+                "Value": true
+              }
+            },
+            "ignore_unknown_instances": null,
+            "path": null
+          }
+        },
+        "properties": {},
+        "ignore_unknown_instances": null,
+        "path": null
+      }
+    ]
+  }
+}

test-projects/multi_partition_game/initial.tree.json

@@ -0,0 +1,242 @@
+{
+  "instances": {
+    "00f207b1-fc18-4088-a45e-caf8cd98f5dd": {
+      "Name": "main",
+      "ClassName": "ModuleScript",
+      "Properties": {
+        "Source": {
+          "Type": "String",
+          "Value": "-- hello, from a/main.lua"
+        }
+      },
+      "Id": "00f207b1-fc18-4088-a45e-caf8cd98f5dd",
+      "Children": [],
+      "Parent": "14fed1a3-ba97-46a6-ae93-ac26bd9471df"
+    },
+    "14fed1a3-ba97-46a6-ae93-ac26bd9471df": {
+      "Name": "Ack",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "14fed1a3-ba97-46a6-ae93-ac26bd9471df",
+      "Children": [
+        "c55fd55c-258e-4a93-a63a-ea243038c9b9",
+        "00f207b1-fc18-4088-a45e-caf8cd98f5dd"
+      ],
+      "Parent": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+    },
+    "c910510c-37a8-4fd8-ae41-01169ccb739c": {
+      "Name": "Bar",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "c910510c-37a8-4fd8-ae41-01169ccb739c",
+      "Children": [
+        "71a95983-c856-4cf2-aee6-bd8a523e80e4"
+      ],
+      "Parent": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+    },
+    "c55fd55c-258e-4a93-a63a-ea243038c9b9": {
+      "Name": "foo",
+      "ClassName": "StringValue",
+      "Properties": {
+        "Value": {
+          "Type": "String",
+          "Value": "Hello world, from a/foo.txt"
+        }
+      },
+      "Id": "c55fd55c-258e-4a93-a63a-ea243038c9b9",
+      "Children": [],
+      "Parent": "14fed1a3-ba97-46a6-ae93-ac26bd9471df"
+    },
+    "71a95983-c856-4cf2-aee6-bd8a523e80e4": {
+      "Name": "something",
+      "ClassName": "ModuleScript",
+      "Properties": {
+        "Source": {
+          "Type": "String",
+          "Value": "-- b/something.lua"
+        }
+      },
+      "Id": "71a95983-c856-4cf2-aee6-bd8a523e80e4",
+      "Children": [],
+      "Parent": "c910510c-37a8-4fd8-ae41-01169ccb739c"
+    },
+    "3b5af13f-c997-4009-915c-0810b0e83032": {
+      "Name": "multi_partition_game",
+      "ClassName": "DataModel",
+      "Properties": {},
+      "Id": "3b5af13f-c997-4009-915c-0810b0e83032",
+      "Children": [
+        "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c",
+        "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+      ],
+      "Parent": null
+    },
+    "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c": {
+      "Name": "HttpService",
+      "ClassName": "HttpService",
+      "Properties": {
+        "HttpEnabled": {
+          "Type": "Bool",
+          "Value": true
+        }
+      },
+      "Id": "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c",
+      "Children": [],
+      "Parent": "3b5af13f-c997-4009-915c-0810b0e83032"
+    },
+    "99eefe5f-ef74-49e6-8a8b-c833e00ca56b": {
+      "Name": "ReplicatedStorage",
+      "ClassName": "ReplicatedStorage",
+      "Properties": {},
+      "Id": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b",
+      "Children": [
+        "14fed1a3-ba97-46a6-ae93-ac26bd9471df",
+        "c910510c-37a8-4fd8-ae41-01169ccb739c"
+      ],
+      "Parent": "3b5af13f-c997-4009-915c-0810b0e83032"
+    }
+  },
+  "root_id": "3b5af13f-c997-4009-915c-0810b0e83032",
+  "metadata": {
+    "00f207b1-fc18-4088-a45e-caf8cd98f5dd": {
+      "ignore_unknown_instances": false,
+      "source_path": "a/main.lua",
+      "project_definition": null
+    },
+    "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "HttpService",
+        {
+          "class_name": "HttpService",
+          "children": {},
+          "properties": {
+            "HttpEnabled": {
+              "Type": "Bool",
+              "Value": true
+            }
+          },
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    },
+    "14fed1a3-ba97-46a6-ae93-ac26bd9471df": {
+      "ignore_unknown_instances": false,
+      "source_path": "a",
+      "project_definition": [
+        "Ack",
+        {
+          "class_name": null,
+          "children": {},
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": "a"
+        }
+      ]
+    },
+    "c55fd55c-258e-4a93-a63a-ea243038c9b9": {
+      "ignore_unknown_instances": false,
+      "source_path": "a/foo.txt",
+      "project_definition": null
+    },
+    "71a95983-c856-4cf2-aee6-bd8a523e80e4": {
+      "ignore_unknown_instances": false,
+      "source_path": "b/something.lua",
+      "project_definition": null
+    },
+    "c910510c-37a8-4fd8-ae41-01169ccb739c": {
+      "ignore_unknown_instances": false,
+      "source_path": "b",
+      "project_definition": [
+        "Bar",
+        {
+          "class_name": null,
+          "children": {},
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": "b"
+        }
+      ]
+    },
+    "99eefe5f-ef74-49e6-8a8b-c833e00ca56b": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "ReplicatedStorage",
+        {
+          "class_name": "ReplicatedStorage",
+          "children": {
+            "Ack": {
+              "class_name": null,
+              "children": {},
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": "a"
+            },
+            "Bar": {
+              "class_name": null,
+              "children": {},
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": "b"
+            }
+          },
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    },
+    "3b5af13f-c997-4009-915c-0810b0e83032": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "multi_partition_game",
+        {
+          "class_name": "DataModel",
+          "children": {
+            "HttpService": {
+              "class_name": "HttpService",
+              "children": {},
+              "properties": {
+                "HttpEnabled": {
+                  "Type": "Bool",
+                  "Value": true
+                }
+              },
+              "ignore_unknown_instances": null,
+              "path": null
+            },
+            "ReplicatedStorage": {
+              "class_name": "ReplicatedStorage",
+              "children": {
+                "Ack": {
+                  "class_name": null,
+                  "children": {},
+                  "properties": {},
+                  "ignore_unknown_instances": null,
+                  "path": "a"
+                },
+                "Bar": {
+                  "class_name": null,
+                  "children": {},
+                  "properties": {},
+                  "ignore_unknown_instances": null,
+                  "path": "b"
+                }
+              },
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": null
+            }
+          },
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    }
+  }
+}

test-projects/multi_partition_game/with_dir.tree.json

@@ -0,0 +1,256 @@
+{
+  "instances": {
+    "b48b369f-5706-4029-9fa6-90651a4910ea": {
+      "Name": "added",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "b48b369f-5706-4029-9fa6-90651a4910ea",
+      "Children": [],
+      "Parent": "14fed1a3-ba97-46a6-ae93-ac26bd9471df"
+    },
+    "00f207b1-fc18-4088-a45e-caf8cd98f5dd": {
+      "Name": "main",
+      "ClassName": "ModuleScript",
+      "Properties": {
+        "Source": {
+          "Type": "String",
+          "Value": "-- hello, from a/main.lua"
+        }
+      },
+      "Id": "00f207b1-fc18-4088-a45e-caf8cd98f5dd",
+      "Children": [],
+      "Parent": "14fed1a3-ba97-46a6-ae93-ac26bd9471df"
+    },
+    "14fed1a3-ba97-46a6-ae93-ac26bd9471df": {
+      "Name": "Ack",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "14fed1a3-ba97-46a6-ae93-ac26bd9471df",
+      "Children": [
+        "b48b369f-5706-4029-9fa6-90651a4910ea",
+        "c55fd55c-258e-4a93-a63a-ea243038c9b9",
+        "00f207b1-fc18-4088-a45e-caf8cd98f5dd"
+      ],
+      "Parent": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+    },
+    "c910510c-37a8-4fd8-ae41-01169ccb739c": {
+      "Name": "Bar",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "c910510c-37a8-4fd8-ae41-01169ccb739c",
+      "Children": [
+        "71a95983-c856-4cf2-aee6-bd8a523e80e4"
+      ],
+      "Parent": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+    },
+    "c55fd55c-258e-4a93-a63a-ea243038c9b9": {
+      "Name": "foo",
+      "ClassName": "StringValue",
+      "Properties": {
+        "Value": {
+          "Type": "String",
+          "Value": "Hello world, from a/foo.txt"
+        }
+      },
+      "Id": "c55fd55c-258e-4a93-a63a-ea243038c9b9",
+      "Children": [],
+      "Parent": "14fed1a3-ba97-46a6-ae93-ac26bd9471df"
+    },
+    "71a95983-c856-4cf2-aee6-bd8a523e80e4": {
+      "Name": "something",
+      "ClassName": "ModuleScript",
+      "Properties": {
+        "Source": {
+          "Type": "String",
+          "Value": "-- b/something.lua"
+        }
+      },
+      "Id": "71a95983-c856-4cf2-aee6-bd8a523e80e4",
+      "Children": [],
+      "Parent": "c910510c-37a8-4fd8-ae41-01169ccb739c"
+    },
+    "3b5af13f-c997-4009-915c-0810b0e83032": {
+      "Name": "multi_partition_game",
+      "ClassName": "DataModel",
+      "Properties": {},
+      "Id": "3b5af13f-c997-4009-915c-0810b0e83032",
+      "Children": [
+        "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c",
+        "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+      ],
+      "Parent": null
+    },
+    "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c": {
+      "Name": "HttpService",
+      "ClassName": "HttpService",
+      "Properties": {
+        "HttpEnabled": {
+          "Type": "Bool",
+          "Value": true
+        }
+      },
+      "Id": "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c",
+      "Children": [],
+      "Parent": "3b5af13f-c997-4009-915c-0810b0e83032"
+    },
+    "99eefe5f-ef74-49e6-8a8b-c833e00ca56b": {
+      "Name": "ReplicatedStorage",
+      "ClassName": "ReplicatedStorage",
+      "Properties": {},
+      "Id": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b",
+      "Children": [
+        "14fed1a3-ba97-46a6-ae93-ac26bd9471df",
+        "c910510c-37a8-4fd8-ae41-01169ccb739c"
+      ],
+      "Parent": "3b5af13f-c997-4009-915c-0810b0e83032"
+    }
+  },
+  "root_id": "3b5af13f-c997-4009-915c-0810b0e83032",
+  "metadata": {
+    "c55fd55c-258e-4a93-a63a-ea243038c9b9": {
+      "ignore_unknown_instances": false,
+      "source_path": "a/foo.txt",
+      "project_definition": null
+    },
+    "99eefe5f-ef74-49e6-8a8b-c833e00ca56b": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "ReplicatedStorage",
+        {
+          "class_name": "ReplicatedStorage",
+          "children": {
+            "Ack": {
+              "class_name": null,
+              "children": {},
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": "a"
+            },
+            "Bar": {
+              "class_name": null,
+              "children": {},
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": "b"
+            }
+          },
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    },
+    "71a95983-c856-4cf2-aee6-bd8a523e80e4": {
+      "ignore_unknown_instances": false,
+      "source_path": "b/something.lua",
+      "project_definition": null
+    },
+    "00f207b1-fc18-4088-a45e-caf8cd98f5dd": {
+      "ignore_unknown_instances": false,
+      "source_path": "a/main.lua",
+      "project_definition": null
+    },
+    "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "HttpService",
+        {
+          "class_name": "HttpService",
+          "children": {},
+          "properties": {
+            "HttpEnabled": {
+              "Type": "Bool",
+              "Value": true
+            }
+          },
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    },
+    "b48b369f-5706-4029-9fa6-90651a4910ea": {
+      "ignore_unknown_instances": false,
+      "source_path": "a/added",
+      "project_definition": null
+    },
+    "3b5af13f-c997-4009-915c-0810b0e83032": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "multi_partition_game",
+        {
+          "class_name": "DataModel",
+          "children": {
+            "HttpService": {
+              "class_name": "HttpService",
+              "children": {},
+              "properties": {
+                "HttpEnabled": {
+                  "Type": "Bool",
+                  "Value": true
+                }
+              },
+              "ignore_unknown_instances": null,
+              "path": null
+            },
+            "ReplicatedStorage": {
+              "class_name": "ReplicatedStorage",
+              "children": {
+                "Ack": {
+                  "class_name": null,
+                  "children": {},
+                  "properties": {},
+                  "ignore_unknown_instances": null,
+                  "path": "a"
+                },
+                "Bar": {
+                  "class_name": null,
+                  "children": {},
+                  "properties": {},
+                  "ignore_unknown_instances": null,
+                  "path": "b"
+                }
+              },
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": null
+            }
+          },
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    },
+    "c910510c-37a8-4fd8-ae41-01169ccb739c": {
+      "ignore_unknown_instances": false,
+      "source_path": "b",
+      "project_definition": [
+        "Bar",
+        {
+          "class_name": null,
+          "children": {},
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": "b"
+        }
+      ]
+    },
+    "14fed1a3-ba97-46a6-ae93-ac26bd9471df": {
+      "ignore_unknown_instances": false,
+      "source_path": "a",
+      "project_definition": [
+        "Ack",
+        {
+          "class_name": null,
+          "children": {},
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": "a"
+        }
+      ]
+    }
+  }
+}

test-projects/multi_partition_game/with_moved_dir.tree.json

@@ -0,0 +1,256 @@
+{
+  "instances": {
+    "866071d6-465a-4b88-8c63-07489d950916": {
+      "Name": "added",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "866071d6-465a-4b88-8c63-07489d950916",
+      "Children": [],
+      "Parent": "c910510c-37a8-4fd8-ae41-01169ccb739c"
+    },
+    "00f207b1-fc18-4088-a45e-caf8cd98f5dd": {
+      "Name": "main",
+      "ClassName": "ModuleScript",
+      "Properties": {
+        "Source": {
+          "Type": "String",
+          "Value": "-- hello, from a/main.lua"
+        }
+      },
+      "Id": "00f207b1-fc18-4088-a45e-caf8cd98f5dd",
+      "Children": [],
+      "Parent": "14fed1a3-ba97-46a6-ae93-ac26bd9471df"
+    },
+    "14fed1a3-ba97-46a6-ae93-ac26bd9471df": {
+      "Name": "Ack",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "14fed1a3-ba97-46a6-ae93-ac26bd9471df",
+      "Children": [
+        "c55fd55c-258e-4a93-a63a-ea243038c9b9",
+        "00f207b1-fc18-4088-a45e-caf8cd98f5dd"
+      ],
+      "Parent": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+    },
+    "c910510c-37a8-4fd8-ae41-01169ccb739c": {
+      "Name": "Bar",
+      "ClassName": "Folder",
+      "Properties": {},
+      "Id": "c910510c-37a8-4fd8-ae41-01169ccb739c",
+      "Children": [
+        "866071d6-465a-4b88-8c63-07489d950916",
+        "71a95983-c856-4cf2-aee6-bd8a523e80e4"
+      ],
+      "Parent": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+    },
+    "c55fd55c-258e-4a93-a63a-ea243038c9b9": {
+      "Name": "foo",
+      "ClassName": "StringValue",
+      "Properties": {
+        "Value": {
+          "Type": "String",
+          "Value": "Hello world, from a/foo.txt"
+        }
+      },
+      "Id": "c55fd55c-258e-4a93-a63a-ea243038c9b9",
+      "Children": [],
+      "Parent": "14fed1a3-ba97-46a6-ae93-ac26bd9471df"
+    },
+    "71a95983-c856-4cf2-aee6-bd8a523e80e4": {
+      "Name": "something",
+      "ClassName": "ModuleScript",
+      "Properties": {
+        "Source": {
+          "Type": "String",
+          "Value": "-- b/something.lua"
+        }
+      },
+      "Id": "71a95983-c856-4cf2-aee6-bd8a523e80e4",
+      "Children": [],
+      "Parent": "c910510c-37a8-4fd8-ae41-01169ccb739c"
+    },
+    "3b5af13f-c997-4009-915c-0810b0e83032": {
+      "Name": "multi_partition_game",
+      "ClassName": "DataModel",
+      "Properties": {},
+      "Id": "3b5af13f-c997-4009-915c-0810b0e83032",
+      "Children": [
+        "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c",
+        "99eefe5f-ef74-49e6-8a8b-c833e00ca56b"
+      ],
+      "Parent": null
+    },
+    "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c": {
+      "Name": "HttpService",
+      "ClassName": "HttpService",
+      "Properties": {
+        "HttpEnabled": {
+          "Type": "Bool",
+          "Value": true
+        }
+      },
+      "Id": "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c",
+      "Children": [],
+      "Parent": "3b5af13f-c997-4009-915c-0810b0e83032"
+    },
+    "99eefe5f-ef74-49e6-8a8b-c833e00ca56b": {
+      "Name": "ReplicatedStorage",
+      "ClassName": "ReplicatedStorage",
+      "Properties": {},
+      "Id": "99eefe5f-ef74-49e6-8a8b-c833e00ca56b",
+      "Children": [
+        "14fed1a3-ba97-46a6-ae93-ac26bd9471df",
+        "c910510c-37a8-4fd8-ae41-01169ccb739c"
+      ],
+      "Parent": "3b5af13f-c997-4009-915c-0810b0e83032"
+    }
+  },
+  "root_id": "3b5af13f-c997-4009-915c-0810b0e83032",
+  "metadata": {
+    "bf8e2d4f-33a0-42a0-8168-1b62d6ac050c": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "HttpService",
+        {
+          "class_name": "HttpService",
+          "children": {},
+          "properties": {
+            "HttpEnabled": {
+              "Type": "Bool",
+              "Value": true
+            }
+          },
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    },
+    "c910510c-37a8-4fd8-ae41-01169ccb739c": {
+      "ignore_unknown_instances": false,
+      "source_path": "b",
+      "project_definition": [
+        "Bar",
+        {
+          "class_name": null,
+          "children": {},
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": "b"
+        }
+      ]
+    },
+    "866071d6-465a-4b88-8c63-07489d950916": {
+      "ignore_unknown_instances": false,
+      "source_path": "b/added",
+      "project_definition": null
+    },
+    "14fed1a3-ba97-46a6-ae93-ac26bd9471df": {
+      "ignore_unknown_instances": false,
+      "source_path": "a",
+      "project_definition": [
+        "Ack",
+        {
+          "class_name": null,
+          "children": {},
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": "a"
+        }
+      ]
+    },
+    "00f207b1-fc18-4088-a45e-caf8cd98f5dd": {
+      "ignore_unknown_instances": false,
+      "source_path": "a/main.lua",
+      "project_definition": null
+    },
+    "99eefe5f-ef74-49e6-8a8b-c833e00ca56b": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "ReplicatedStorage",
+        {
+          "class_name": "ReplicatedStorage",
+          "children": {
+            "Ack": {
+              "class_name": null,
+              "children": {},
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": "a"
+            },
+            "Bar": {
+              "class_name": null,
+              "children": {},
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": "b"
+            }
+          },
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    },
+    "71a95983-c856-4cf2-aee6-bd8a523e80e4": {
+      "ignore_unknown_instances": false,
+      "source_path": "b/something.lua",
+      "project_definition": null
+    },
+    "c55fd55c-258e-4a93-a63a-ea243038c9b9": {
+      "ignore_unknown_instances": false,
+      "source_path": "a/foo.txt",
+      "project_definition": null
+    },
+    "3b5af13f-c997-4009-915c-0810b0e83032": {
+      "ignore_unknown_instances": true,
+      "source_path": null,
+      "project_definition": [
+        "multi_partition_game",
+        {
+          "class_name": "DataModel",
+          "children": {
+            "HttpService": {
+              "class_name": "HttpService",
+              "children": {},
+              "properties": {
+                "HttpEnabled": {
+                  "Type": "Bool",
+                  "Value": true
+                }
+              },
+              "ignore_unknown_instances": null,
+              "path": null
+            },
+            "ReplicatedStorage": {
+              "class_name": "ReplicatedStorage",
+              "children": {
+                "Ack": {
+                  "class_name": null,
+                  "children": {},
+                  "properties": {},
+                  "ignore_unknown_instances": null,
+                  "path": "a"
+                },
+                "Bar": {
+                  "class_name": null,
+                  "children": {},
+                  "properties": {},
+                  "ignore_unknown_instances": null,
+                  "path": "b"
+                }
+              },
+              "properties": {},
+              "ignore_unknown_instances": null,
+              "path": null
+            }
+          },
+          "properties": {},
+          "ignore_unknown_instances": null,
+          "path": null
+        }
+      ]
+    }
+  }
+}

test-projects/single_partition_game/default.project.json

@@ -11,10 +11,7 @@
     "HttpService": {
       "$className": "HttpService",
       "$properties": {
-        "HttpEnabled": {
-          "Type": "Bool",
-          "Value": true
-        }
+        "HttpEnabled": true
       }
     }
   }