Complete the public facade adapter boundary

docs/internal/runner.md

@@ -25,8 +25,9 @@ contracts.
 - an optional `OutputRepairer`.
 
 `NewRunner` constructs a runner without a repairer. `NewRunnerWithRepairer`
-accepts one explicitly. Adapters and the public engine choose concrete
-repositories and readers; the runner does not load application configuration.
+accepts one explicitly. The public engine chooses concrete repositories and
+readers; executable adapters reach the runner only through that engine. The
+runner does not load application configuration.
 
 ## Prepare Flow
 
@@ -68,8 +69,9 @@ validation mode is JSON or JSON Schema. Each repair receives the previous
 output, validation errors, effective target, structured-output specification,
 and attempt metadata; every repaired result is validated again.
 
-`NewDefaultOutputRepairer` delegates to the injected LLM client. CLI, HTTP, and
-the public engine use `NewRunner` and therefore do not inject this repairer.
+`NewDefaultOutputRepairer` delegates to the injected LLM client. The public
+engine, and therefore CLI and HTTP, uses `NewRunner` and does not inject this
+repairer.
 
 ## Error Translation
 
@@ -104,7 +106,6 @@ values in prepared or run results.
 Inspect:
 
 - `internal/usecase/runner_test.go`
-- `internal/usecase/integration_test.go`
 - `engine_test.go`
 
 When changing orchestration: