diff --git a/tools/catalog.js b/tools/catalog.js
index 4fece9253f..e88ac64c28 100644
--- a/tools/catalog.js
+++ b/tools/catalog.js
@@ -191,7 +191,7 @@ _.extend(Catalog.prototype, {
         deps.push(packageName);
         if (constraint) {
           var utils = require('./utils.js');
-          var vers = utils.parseConstraint(constraint);
+          var vers = utils.parseVersionConstraint(constraint);
           vers['packageName'] = packageName;
           constr.push(vers);
         }
diff --git a/tools/commands.js b/tools/commands.js
index e6e43799bb..3e0fc168e8 100644
--- a/tools/commands.js
+++ b/tools/commands.js
@@ -496,6 +496,33 @@ main.registerCommand({
     return;
   }
 
+
+  // OK, let's figure out what release fits with our package constraints!
+  // XXX this will actually be a loop over possible releases in the non-force
+  //     case
+  // XXX better error checking on name
+  var releaseRecord = catalog.getReleaseVersion(
+    release.current.name.split('@')[0], release.current.name.split('@')[1]);
+  if (!releaseRecord)
+    throw Error("missing release record?");
+  var directDependencies = project.getDirectDependencies(options.appDir);
+  var previousVersions = project.getIndirectDependencies(options.appDir);
+  var constraints = project.combinedConstraints(
+    directDependencies, releaseRecord.packages);
+  var solutionVersions = catalog.resolveConstraints(
+    constraints, { previousSolution: previousVersions });
+  if (!solutionVersions) {
+    // XXX text
+    process.stderr.write(
+      "Couldn't solve the update to " + release.current.name + ". Ah well.\n");
+    return 1;
+  }
+  project.setDependencies(options.appDir, directDependencies.appDeps,
+                          solutionVersions);
+  // XXX did we have to change some package versions? we should probably
+  //     mention that fact.
+
+
   // Find upgraders (in order) necessary to upgrade the app for the new
   // release (new metadata file formats, etc, or maybe even updating renamed
   // APIs).
diff --git a/tools/package-loader.js b/tools/package-loader.js
index 65ed230840..250263c571 100644
--- a/tools/package-loader.js
+++ b/tools/package-loader.js
@@ -5,7 +5,7 @@ var packageCache = require('./package-cache.js');
 var catalog = require('./catalog.js');
 var utils = require('./utils.js');
 var buildmessage = require('./buildmessage.js');
-var Unipackage = require('./unipackage.js').Unipackage;
+var unipackage = require('./unipackage.js');
 
 // options:
 //  - versions: a map from package name to the version to use.  or null to only
@@ -46,7 +46,7 @@ _.extend(PackageLoader.prototype, {
         return null;
       buildmessage.error("package not available: " + name);
       // recover by returning a dummy (empty) package
-      var pkg = new Unipackage;
+      var pkg = new unipackage.Unipackage;
       pkg.initEmpty(name);
       return pkg;
     }
diff --git a/tools/project.js b/tools/project.js
index 29df644140..36b7147371 100644
--- a/tools/project.js
+++ b/tools/project.js
@@ -217,7 +217,7 @@ var meteorReleaseFilePath = function (appDir) {
 // field with the version constriant, and boolean values for exact and weak. (We
 // use this format because we treat release packages as exact weak
 // dependencies.) The result of this gets passed into the constraint solver.
-project.combinedConstraints = function (deps) {
+project.combinedConstraints = function (deps, releasePackages) {
   var allDeps = [];
 
   _.each(deps.appDeps, function (constraint, packageName) {
@@ -230,13 +230,13 @@ project.combinedConstraints = function (deps) {
                           utils.parseVersionConstraint(constraint)));
   });
   });
-  var releasePackages = release.current.manifest ? release.current.manifest.packages : {};
+
   _.each(releasePackages, function(version, name) {
     allDeps.push({packageName: name, version: version, weak: true, exact: true});
   });
+  // XXX grr
   allDeps.push({packageName: "ctl", version:  null });
 
-
   return allDeps;
 };
 
@@ -249,19 +249,20 @@ project.combinedConstraints = function (deps) {
 project.generatePackageLoader = function (appDir) {
   var versions = project.getIndirectDependencies(appDir);
   var packages = project.getDirectDependencies(appDir);
+  var releasePackages =
+        release.current.isProperRelease() ? release.current.getPackages() : {};
 
   // package name -> list of version constraints
-  var allPackages = project.combinedConstraints(packages);
+  var allPackages = project.combinedConstraints(packages, releasePackages);
   // Call the constraint solver.
-  var newVersions = catalog.catalog.resolveConstraints(allPackages,
-                                              { previousSolution: versions });
+  var newVersions = catalog.catalog.resolveConstraints(
+    allPackages, { previousSolution: versions });
   if ( ! newVersions) {
     console.log("Cannot compute versions for: ", allPackages);
     process.exit(1);
   }
 
   // Download any necessary package builds and write out the new versions file.
-  delete packages["ctl"];
   project.setDependencies(appDir, packages.appDeps, newVersions);
 
   var PackageLoader = require('./package-loader.js');
diff --git a/tools/release.js b/tools/release.js
index f97a931150..90d7684f17 100644
--- a/tools/release.js
+++ b/tools/release.js
@@ -11,7 +11,7 @@ var Release = function (options) {
   var self = this;
 
   // If an actual, proper, "released" release, the name of the
-  // release, eg, "1.0". If not a proper release, null.
+  // release, eg, "METEOR-CORE@1.0". If not a proper release, null.
   self.name = options.name;
 
   if (self.name === null) {
diff --git a/tools/utils.js b/tools/utils.js
index 15c4531212..bad753d691 100644
--- a/tools/utils.js
+++ b/tools/utils.js
@@ -138,6 +138,8 @@ exports.randomPort = function () {
   return 20000 + Math.floor(Math.random() * 10000);
 };
 
+// XXX minimize duplication between this, tools/package-version-parser,
+//     and packages/package-version-parser
 // Given a version constraint string of the form "1.0.0" or "=1.2.3-rc0",
 // return an object with keys:
 // - version: the version part of the constraint, such as "1.0.0" or "1.2.3"
@@ -149,7 +151,7 @@ exports.randomPort = function () {
 // gracefully and print a reasonable error if the user typos their
 // version constraint in package or whatever
 exports.parseVersionConstraint = function (versionString) {
-  var versionDesc = { version: null, exact: false };
+  var versionDesc = { version: null, type: 'compatible-with' };
 
   // XXX #noconstraint #geoff #changed
   // XXX remove none when it is no longer used
@@ -158,7 +160,7 @@ exports.parseVersionConstraint = function (versionString) {
   }
 
   if (versionString.charAt(0) === '=') {
-    versionDesc.exact = true;
+    versionDesc.type = 'exactly';
     versionString = versionString.substr(1);
   }