docs: add design diagram

README.md

@@ -33,4 +33,58 @@ const tester = await setupToolboxTester(
 
 // Run the tests with each of the conductors and report combined results
 await tester.start()
+```
+
+## Design
+
+```mermaid
+graph
+    FS[(FS)]
+    FsWatcher
+    Manager[TestRunManager]
+    Conductor[TestConductor]
+    Run(TestRunStack)
+    RunInstance(TestRunInstance)
+    Suite(TestSuite)
+    subgraph TargetEnv[Target environment]
+        Runner[TestRunner]
+        SetupFiles[(Setup module)]
+        TestSuiteFile[(Test suite file)]
+        Test([Test])
+        ReporterClient(TestReporterClient)
+        Imports[(Imported module)]
+    end
+    ReporterServer(TestReporterServer)
+    RunnerServer
+    FileServer
+    FileProvider
+    FileLoader
+
+
+    FsWatcher -- watch --> FS
+    FsWatcher -- report list of files --> mapToTestFile[[map to test suite files]] --> Manager
+    Manager -- create --> Run
+    Manager -- filter/exec --> Suite
+    Run --- RunInstance
+    RunInstance --- Conductor
+    RunInstance --- Suite
+    Suite -- delegate execution --> Conductor
+    Conductor -- launch target environment --> TargetEnv
+    Conductor ---- ReporterServer
+    Conductor -- load --> Runner
+    Conductor -- load --> SetupFiles
+    Conductor -- load --> TestSuiteFile
+    TestSuiteFile -- create --> Test
+    RunnerServer -- serves --> Runner
+    FileServer -- serves --> TestSuiteFile
+    FileServer -. serves .-> Imports
+    FileServer ---- FileProvider
+    FsWatcher -- invalidates --> FileProvider
+    FileProvider ---- FileLoader
+    FileLoader -- load and transform --> FS
+    TestSuiteFile -- import --> Imports
+    Runner -- execute --> Test
+    Runner -- report --> ReporterClient
+    ReporterClient -- report --> ReporterServer
+    ReporterServer -- report --> Suite
 ```