Kill switches — `get_killswitch`

A kill switch is an admin resource that ships in the flags blob alongside gates and configs. get_killswitch reads it and returns a boolean. It is not user-scoped. After Shipeasy.configure, read it through the bound Shipeasy::Client.new(user).

# construct once per callsite (cheap; binds the user)
flags = Shipeasy::Client.new(current_user)

if flags.get_killswitch("payments_circuit_breaker")
  # the kill switch is engaged — short-circuit the risky path
  return fallback
end

Named switches

Besides its single top-level on/off value, a kill switch can carry named per-key switches — independently-flippable booleans, each under a key you choose (one per payment provider, region, vendor, …). These are configured on the kill switch itself (in the dashboard "switches" feature, or in an offline snapshot — see below); the SDK only reads them. They do not exist until you add them.

Pass that key as the second argument, switch_key, to check one named switch instead of the top-level value. The natural pattern is to pass the thing you're about to do as the key, and let the kill switch decide:

provider = "stripe"   # the variable you check against the configured switches

flags = Shipeasy::Client.new(current_user)

if flags.get_killswitch("payments_circuit_breaker", provider)
  # the "stripe" switch is engaged → skip Stripe, take the fallback
  return use_backup_processor
end

Resolution order for get_killswitch(name, switch_key):

1. If the kill switch has a named switch matching switch_key, that switch's boolean is returned.
2. Otherwise — the key isn't configured on the kill switch — it falls back to the top-level value. So an unknown/unconfigured key behaves exactly like get_killswitch(name) with no key.

That fallback lets you wire the key everywhere first and turn individual switches on later: until you actually add the "stripe" switch, every get_killswitch("payments_circuit_breaker", "stripe") just reflects the kill switch's overall state. Unknown kill switches return false.

Configuring switches for a test

In production these are set in the dashboard. To exercise them in a test, put a switches map on the kill switch in an offline snapshot. The blob shape is top-level killed + a switches hash:

Shipeasy.configure_for_offline(snapshot: {
  "flags" => {
    "gates" => {}, "configs" => {},
    "killswitches" => {
      "payments_circuit_breaker" => {
        "killed"   => false,                       # top-level (fallback)
        "switches" => { "stripe" => true, "paypal" => false },
      },
    },
  },
  "experiments" => {},
})

c = Shipeasy::Client.new({ "user_id" => "u_1" })
c.get_killswitch("payments_circuit_breaker")           # => false (top-level)
c.get_killswitch("payments_circuit_breaker", "stripe") # => true  (named switch)
c.get_killswitch("payments_circuit_breaker", "paypal") # => false
c.get_killswitch("payments_circuit_breaker", "other")  # => false (falls back)

Kill switches are also folded into normal gate evaluation (a killed gate reports reason OFF from get_flag_detail); get_killswitch is the explicit read of that same state.