Doc: Clarify TestContext lifecycle and hook execution order

doc/api/test.md

@@ -4078,6 +4078,46 @@ An instance of `TestContext` is passed to each test function in order to
 interact with the test runner. However, the `TestContext` constructor is not
 exposed as part of the API.
 
+### TestContext lifecycle
+
+A new `TestContext` instance is created for every test execution.
+
+The context remains available throughout the execution of the test, including
+its associated hooks.
+
+Each subtest receives its own independent `TestContext` instance,
+rather than sharing the parent's context.
+
+### Example
+
+```mjs
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+test('parent', async (parentContext) => {
+  await parentContext.test('child', (childContext) => {
+    assert.notStrictEqual(parentContext, childContext);
+  });
+});
+```
+
+In this example, the parent test and the subtest each receive their own
+`TestContext` instance.
+
+### Execution order
+
+When hooks are registered on a test that contains subtests, they execute in
+the following order for each subtest:
+
+1. `before`
+2. `beforeEach`
+3. subtest execution
+4. `afterEach`
+5. `after`
+
+When multiple hooks of the same type are registered, they execute in
+registration order.
+
 ### `context.before([fn][, options])`
 
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