Rename to pre_commit and put it in <your-project>/.git/hooks to require commits to follow policy

pre_commit.rb

#!/usr/bin/env ruby

# Compare commit message formatting to formatting policy.
#
# Message should include a Pivotal Story ID reference 
# and an optional state change keyword.
#
# Example: [Fixes #12345]

message_file = ARGV[0]
message = File.read(message_file)

$actions = %w(fix fixes complete completes finish finishes)
$regex = /\[(#{$actions.join("|")})?\s?#(\d+)\]/i

if !$regex.match(message)
  puts "[POLICY] Your message does not include a story ID"
  exit 1
end