Separate Restoring from Preparing

proposals/SeparateRestorePrepare.md

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+# Separation of restore and prepare
+
+Currently Cordova has a feature to save platform and plugins to config.xml, and
+restore them when running `cordova prepare`.  While this is incredible useful
+functionality, the combining of two seperable actions into a single command
+leads to unexpected behaviour.  The act of restoring should be split into its
+own Cordova command, unrelated to the act of preparing.
+
+This is help by reducing the complexity of the prepare logic, and significantly
+improving the performance.  Previously, we would restore a platform, prepare
+it, install plugins, and then prepare again
+[(CB-11589)](https://issues.apache.org/jira/browse/CB-11589).  Attempting to
+fix this caused unexpected issues with plugins not being installed when adding
+new platforms [(CB-11698)](https://issues.apache.org/jira/browse/CB-11698), and
+the current code now has issues with calling prepare before installing plugins
+rather than after installing them
+[(CB-11777)](https://issues.apache.org/jira/browse/CB-11777).
+
+The current code also results in unexpected restoring when prepare is called as
+part of another command, such as build.  Someone can run `cordova prepare ios`
+to restore the iOS platform and plugins, but running `cordova build ios` will
+(unintuitively) restore all platforms -- without building them.
+
+
+Cordova should have a `cordova restore` or `cordova install` (to match npm)
+command to restore platforms and plugins.
+
+Cordova should not restore by default when running `cordova prepare`, but could
+optionally have a `--restore` flag to maintain the current behaviour.
+
+
+This should happen in Cordova 7.0, coinciding with the [saving of
+platforms/plugins to
+package.json](https://github.com/cordova/cordova-discuss/pull/53) instead of
+config.xml.