diff --git a/internal/runner/runner.go b/internal/runner/runner.go
index 0c1c376..25f8cc8 100644
--- a/internal/runner/runner.go
+++ b/internal/runner/runner.go
@@ -1,3 +1,4 @@
+// Package runner drives the observe-decide-act loop that steps a spec against a device.
 package runner
 
 import (
diff --git a/internal/testrun/testrun.go b/internal/testrun/testrun.go
index f2c26f8..6d58441 100644
--- a/internal/testrun/testrun.go
+++ b/internal/testrun/testrun.go
@@ -1,3 +1,4 @@
+// Package testrun wires together the device, bundler, runner, and verifier into a single test pipeline.
 package testrun
 
 import (