diff --git a/common/modules/base.jsm b/common/modules/base.jsm
index 904491f5..5b337207 100644
--- a/common/modules/base.jsm
+++ b/common/modules/base.jsm
@@ -128,6 +128,8 @@ let jsmodules = {
             memoize(target || this, name, function (name) require(module)[name]);
     }
 };
+jsmodules.jsmodules = jsmodules;
+
 let use = {};
 let loaded = {};
 let currentModule;
diff --git a/common/modules/contexts.jsm b/common/modules/contexts.jsm
index b109cc61..8a9ae42b 100644
--- a/common/modules/contexts.jsm
+++ b/common/modules/contexts.jsm
@@ -8,9 +8,12 @@ try {
 
 Components.utils.import("resource://dactyl/bootstrap.jsm");
 defineModule("contexts", {
-    exports: ["Contexts", "Group", "contexts"]
+    exports: ["Contexts", "Group", "contexts"],
+    require: ["services", "util"]
 }, this);
 
+this.lazyRequire("overlay", ["overlay"]);
+
 var Const = function Const(val) Class.Property({ enumerable: true, value: val });
 
 var Group = Class("Group", {
@@ -85,6 +88,17 @@ var Group = Class("Group", {
 });
 
 var Contexts = Module("contexts", {
+    init: function () {
+        this.pluginModules = {};
+    },
+
+    cleanup: function () {
+        for each (let module in this.pluginModules)
+            util.trapErrors("cleanup", module);
+
+        this.pluginModules = {};
+    },
+
     Local: function Local(dactyl, modules, window) ({
         init: function () {
             const contexts = this;
@@ -195,7 +209,7 @@ var Contexts = Module("contexts", {
 
         let name = isPlugin ? file.getRelativeDescriptor(isPlugin).replace(File.PATH_SEP, "-")
                             : file.leafName;
-        let id   = name.replace(/\.[^.]*$/, "").replace(/-([a-z])/g, function (m, n1) n1.toUpperCase());
+        let id   = util.camelCase(name.replace(/\.[^.]*$/, ""));
 
         let contextPath = file.path;
         let self = Set.has(plugins, contextPath) && plugins.contexts[contextPath];
@@ -205,7 +219,7 @@ var Contexts = Module("contexts", {
 
         if (self) {
             if (Set.has(self, "onUnload"))
-                self.onUnload();
+                util.trapErrors("onUnload", self);
         }
         else {
             self = args && !isArray(args) ? args : newContext.apply(null, args || [userContext]);
@@ -216,10 +230,16 @@ var Contexts = Module("contexts", {
 
                 CONTEXT: Const(self),
 
+                set isGlobalModule(val) {
+                    // Hack.
+                    if (val)
+                        throw Contexts;
+                },
+
                 unload: Const(function unload() {
                     if (plugins[this.NAME] === this || plugins[this.PATH] === this)
                         if (this.onUnload)
-                            this.onUnload();
+                            util.trapErrors("onUnload", this);
 
                     if (plugins[this.NAME] === this)
                         delete plugins[this.NAME];
@@ -270,6 +290,74 @@ var Contexts = Module("contexts", {
         return this.Context(file, group, [this.modules.userContext, true]);
     },
 
+    Module: function Module(uri, isPlugin) {
+        const { io, plugins } = this.modules;
+
+        let canonical = uri.spec;
+        if (uri.scheme == "resource")
+            canonical = services["resource:"].resolveURI(uri);
+
+        if (uri instanceof Ci.nsIFileURL)
+            var file = File(uri.file);
+
+        let isPlugin = array.nth(io.getRuntimeDirectories("plugins"),
+                                 function (dir) dir.contains(file, true),
+                                 0);
+
+        let name = isPlugin && file && file.getRelativeDescriptor(isPlugin)
+                                           .replace(File.PATH_SEP, "-");
+        let id   = util.camelCase(name.replace(/\.[^.]*$/, ""));
+
+        let self = Set.has(this.pluginModules, canonical) && this.pluginModules[canonical];
+
+        if (!self) {
+            self = Object.create(jsmodules);
+
+            update(self, {
+                NAME: Const(id),
+
+                PATH: Const(file && file.path),
+
+                CONTEXT: Const(self),
+
+                get isGlobalModule() true,
+                set isGlobalModule(val) {
+                    util.assert(val, "Loading non-global module as global",
+                                false);
+                },
+
+                unload: Const(function unload() {
+                    if (contexts.pluginModules[canonical] == this) {
+                        if (this.onUnload)
+                            util.trapErrors("onUnload", this);
+
+                        delete contexts.pluginModules[canonical];
+                    }
+
+                    for each (let { plugins } in overlay.modules)
+                        if (plugins[this.NAME] == this)
+                            delete plugins[this.name];
+                })
+            });
+
+            JSMLoader.loadSubScript(uri.spec, self, File.defaultEncoding);
+            this.pluginModules[canonical] = self;
+        }
+
+        // This belongs elsewhere
+        if (isPlugin)
+            Object.defineProperty(plugins, self.NAME, {
+                configurable: true,
+                enumerable: true,
+                get: function () self,
+                set: function (val) {
+                    util.dactyl(val).reportError(FailedAssertion(_("plugin.notReplacingContext", self.NAME), 3, false), true);
+                }
+            });
+
+        return self;
+    },
+
     context: null,
 
     /**
diff --git a/common/modules/io.jsm b/common/modules/io.jsm
index 0587ea40..85271b4d 100644
--- a/common/modules/io.jsm
+++ b/common/modules/io.jsm
@@ -16,6 +16,7 @@ defineModule("io", {
 }, this);
 
 this.lazyRequire("config", ["config"]);
+this.lazyRequire("contexts", ["Contexts", "contexts"]);
 
 // TODO: why are we passing around strings rather than file objects?
 /**
@@ -167,8 +168,14 @@ var IO = Module("io", {
 
                     let uri = services.io.newFileURI(file);
 
-                    // handle pure JavaScript files specially
-                    if (/\.js$/.test(filename)) {
+                    let sourceJSM = function sourceJSM() {
+                        context = contexts.Module(uri);
+                        dactyl.triggerObserver("io.source", context, file, file.lastModifiedTime);
+                    }
+
+                    if (/\.js,$/.test(filename))
+                        sourceJSM();
+                    else if (/\.js$/.test(filename)) {
                         try {
                             var context = contexts.Script(file, params.group);
                             if (Set.has(this._scriptNames, file.path))
@@ -178,15 +185,21 @@ var IO = Module("io", {
                             dactyl.triggerObserver("io.source", context, file, file.lastModifiedTime);
                         }
                         catch (e) {
-                            if (e.fileName && !(e instanceof FailedAssertion))
-                                try {
-                                    e.fileName = util.fixURI(e.fileName);
-                                    if (e.fileName == uri.spec)
-                                        e.fileName = filename;
-                                    e.echoerr = <>{e.fileName}:{e.lineNumber}: {e}</>;
-                                }
-                                catch (e) {}
-                            throw e;
+                            if (e == Contexts) { // Hack;
+                                context.unload();
+                                sourceJSM();
+                            }
+                            else {
+                                if (e.fileName && !(e instanceof FailedAssertion))
+                                    try {
+                                        e.fileName = util.fixURI(e.fileName);
+                                        if (e.fileName == uri.spec)
+                                            e.fileName = filename;
+                                        e.echoerr = <>{e.fileName}:{e.lineNumber}: {e}</>;
+                                    }
+                                    catch (e) {}
+                                throw e;
+                            }
                         }
                     }
                     else if (/\.css$/.test(filename))