README.md

However, grunt build will not complete because it no concat targets are found (nor uglify targets, for that matter). If it were working properly, the concat:generated and uglify:generated tasks would have been added to the loaded grunt tasks, which would then be executed by usemin in the last step of my build.

Hopefully this is all clear!

Gruntfile.js

'use strict';

var path = require('path');

module.exports = function (grunt) {

    // Load externally-defined tasks
    grunt.loadTasks('tasks/grunt');

    // Load grunt tasks automatically
    require('load-grunt-config')(grunt, {
        configPath: path.join(process.cwd(), 'tasks/grunt/options'),
        init: true,
        config: {
            config: {
                app: 'app',
                dist: 'dist',
                tmp: '.tmp',
                test: 'test'
            }
        },
        loadGruntTasks: {
            pattern: 'grunt-*'
        }
    });

    // Time how long tasks take. Can help when optimizing build times
    require('time-grunt')(grunt);
};



// tasks/grunt/options/useminPrepare.js:
module.exports = {
    // Reads HTML for usemin blocks to enable smart builds that automatically
    // concat, minify and revision files. Creates configurations in memory so
    // additional tasks can operate on them
    options: {
        dest: '<%= config.dist %>'
    },
    html: '<%= config.app %>/index.html'
};

// tasks/grunt/options/usemin.js:
module.exports = {
    // Performs rewrites based on rev and the useminPrepare configuration
    options: {
        assetsDirs: ['<%= config.dist %>', '<%= config.dist %>/images']
    },
    html: ['<%= config.dist %>/{,*/}*.html']
};


// here is my build task.  useminPrepare is included in 'concurrent:dist'
module.exports = function(grunt) {
    grunt.registerTask('build', [
        'clean:dist',
        'includereplace',
        'jshint',
        'modernizr',
        'concurrent:dist',
        'copy',
        'concat',
        'uglify',
        'usemin'
    ]);
};

output.js

// The preceding configuration gives me the correct useminPrepare output:

// Running "useminPrepare:html" (useminPrepare) task
// Going through app/index.html to update the config
// Looking for build script HTML comment blocks

// Configuration is now:
{
    concat: {
        files: {
            '.tmp/concat/scripts/head-scripts.js': [
                'app/scripts/vendor/modernizr.js'
            ],
            '.tmp/concat/scripts/app-prod.js': [
                'app/scripts/main.js',
                'app/scripts/app.js'
            ]
        },
        generated: {
            files: [
                {
                    dest: '.tmp/concat/scripts/head-scripts.js',
                    src: [
                        'app/scripts/vendor/modernizr.js'
                    ]
                },
                {
                    dest: '.tmp/concat/scripts/app-prod.js',
                    src: [
                        'app/scripts/main.js',
                        'app/scripts/app.js'
                    ]
                }
            ]
        }
    }
    uglify: {
        files: {
            '<%= config.dist %>/concat/scripts/head-scripts.js': [
                '.tmp/concat/scripts/head-scripts.js'
            ],
            '<%= config.dist %>/concat/scripts/app-prod.js': [
                '.tmp/scripts/app-prod.js'
            ]
        },
        generated: {
            files: [
                {
                    dest: 'dist/scripts/head-scripts.js',
                    src: [
                        '.tmp/concat/scripts/head-scripts.js'
                    ]
                },
                {
                    dest: 'dist/scripts/app-prod.js',
                    src: [
                        '.tmp/concat/scripts/app-prod.js'
                    ]
                }
            ]
        }
    }
}