Laravel "Class not found..." when running artisan commands (but not composer) - php

Question

I have an app I've been working on for a few weeks; I'm using Vagrant+Homestead for local development, and Forge+Linode for a staging environment; until a few days ago, my workflow was working fine, however now when the deployment script runs in Forge (in particular composer install), it gets an error:
[RuntimeException]
Error Output: PHP Fatal error: Class 'Reputationhub\ReputationhubServiceProvider' not found in /home/vagrant/Sites/reputationhu
b/vendor/laravel/framework/src/Illuminate/Foundation/ProviderRepository.php on line 157
PHP Stack trace:
PHP 1. {main}() /home/vagrant/Sites/reputationhub/artisan:0
PHP 2. require_once() /home/vagrant/Sites/reputationhub/artisan:30
PHP 3. require() /home/vagrant/Sites/reputationhub/bootstrap/start.php:60
PHP 4. Illuminate\Foundation\ProviderRepository->load() /home/vagrant/Sites/reputationhub/vendor/laravel/framework/src/Illumin
ate/Foundation/start.php:210
PHP 5. Illuminate\Foundation\ProviderRepository->compileManifest() /home/vagrant/Sites/reputationhub/vendor/laravel/framework/
src/Illuminate/Foundation/ProviderRepository.php:57
PHP 6. Illuminate\Foundation\ProviderRepository->createProvider() /home/vagrant/Sites/reputationhub/vendor/laravel/framework/s
rc/Illuminate/Foundation/ProviderRepository.php:121
It is actually the subcommand php artisan clear-compiled that composer runs afterward that is failing. If I run that on it's own, same problem. Running composer install --no-script runs ok.
When I look at vendor/composer/autoload_classmap.php, it's missing all sorts of things, and is only a few lines long (it's normally much larger), so whatever Laravel is doing is not properly finding the correct classes.
The odd thing is that running composer dump-autoload -o seems to fix it; the autoload_classmap.php file finds everything, and the app runs fine, until php artisan ... tries to do anything, then it breaks the app.
The end result is that the Forge deployment is broken; I can manually jump onto the server and run composer dump-autoload -o to fix it, but that seems wrong.
I think I've been rather thorough about researching solutions, but so far I can't find anything, so any help would be appreciated.
UPDATE: further clarification
This is Laravel 4.2.
My composer.json autoload section looks like this:
...
"autoload": {
"classmap": [
"app/commands",
"app/controllers",
"app/database/migrations",
"app/database/seeds",
"app/tests/TestCase.php"
],
"psr-4": {
"Reputationhub\\": "app/"
},
"files": []
},
...
The provider has been added to the "providers" array in app.php like this:
...
'Reputationhub\ReputationhubServiceProvider',
...
And my provider file (at app/Reputationhub/ReputationhubServiceProvider.php) looks like this:
<?php namespace Reputationhub;
use Reputationhub\EventSubscribers\MetricsEventSubscriber;
use Illuminate\Support\ServiceProvider;
class ReputationhubServiceProvider extends ServiceProvider {
...
}
Update 2: more testing
Not sure what it does, but composer install seems to do something bad that breaks the app. To fix it, rather than using composer install in the deployment script (which will subsequently call php artisan clear-compiled and php artisan optimize, both of which will throw errors), if I use this it will repair itself:
...
composer install --no-scripts
composer dump-autoload -o
php artisan dump-autoload
...