deps path: caller errors print as a clean dev: line, not a backtrace

lib/dev/deps/accessor.rb

@@ -21,11 +21,16 @@ module Deps
     class Accessor
       extend T::Sig
 
-      class UsageError < StandardError; end
-      class NotLockedError < StandardError; end
-      class PlatformNotLockedError < StandardError; end
-      class NotCachedError < StandardError; end
-      class NotInstalledError < StandardError; end
+      # All five are the caller's problem, not dev's, so they descend from
+      # the two roots Runner#exit_for prints as a clean `dev: …` line (exit
+      # 1): a malformed invocation or an operand the lockfile does not know
+      # is an ArgumentError; a locked dep whose artifact is not provisioned
+      # yet ("run dev up") is a RuntimeError.
+      class UsageError < RuntimeError; end
+      class NotLockedError < ArgumentError; end
+      class PlatformNotLockedError < ArgumentError; end
+      class NotCachedError < RuntimeError; end
+      class NotInstalledError < RuntimeError; end
 
       USAGE = "usage: dev deps path ficsit <mod> <platform> | dev deps path xcode | dev deps path gh <name>"
 

test/dev/deps/accessor_test.rb

@@ -342,4 +342,17 @@ def setup_locked_gh(dir, installed: true, marker_version: GH_ENGINE_TAG)
     "no integration" | []
     "too many arguments" | ["ficsit", "SML", "Windows", "extra"]
   end
+
+  test "#{error} is a #{parent}: the CLI boundary prints it as a clean `dev:` line, never a backtrace" do
+    Expect "operand errors are ArgumentErrors, not-yet-provisioned states RuntimeErrors (both exit 1 in Runner#exit_for)"
+    error.superclass == parent
+
+    Where
+    error | parent
+    Dev::Deps::Accessor::UsageError | RuntimeError
+    Dev::Deps::Accessor::NotLockedError | ArgumentError
+    Dev::Deps::Accessor::PlatformNotLockedError | ArgumentError
+    Dev::Deps::Accessor::NotCachedError | RuntimeError
+    Dev::Deps::Accessor::NotInstalledError | RuntimeError
+  end
 end