diff --git a/packages/effect-bun-test/README.md b/packages/effect-bun-test/README.md
index 1636bc9..b570e83 100644
--- a/packages/effect-bun-test/README.md
+++ b/packages/effect-bun-test/README.md
@@ -355,6 +355,7 @@ structural changes, as opposed to the mechanical renames:
 | `Schedule.recurs(n) ∘ elapsed ∘ whileOutput(≤ t)` | `Schedule.recurs(n)` + `Schedule.upTo({ duration: t })` | `Schedule` lost `compose`, `elapsed` and `whileOutput`; `upTo` expresses the same bound directly. |
 | `Arbitrary.make(schema)` | `Schema.toArbitrary(schema)(fc)` | The standalone `Arbitrary` module is gone; derivation now returns a factory over the FastCheck namespace. |
 | `Logger.replace(defaultLogger, l)` | swap over `References.CurrentLoggers` | `Logger.layer([l])` would install *only* `l`, silently dropping the ambient `tracerLogger`; `log-capture` does the one-for-one swap explicitly to preserve v3 behaviour. |
+| `logLevel.label` (`'WARN'`, `'OFF'`) | `logLevelLabel(logLevel)` | v4 models a level as a bare string union member (`'Warn'`, `'None'`) rather than an object carrying a `label`. Every level differs in case and the off sentinel differs in spelling, so a caller that kept `level === 'WARN'` would not fail — it would match nothing and quietly assert nothing. `CapturedLog.level` therefore stays on the v3 labels, and `logLevelLabel` is exported so a caller building its own `Logger.make` sink can label a raw v4 level the same way. |
 
 ### Additions (no upstream counterpart)
 
diff --git a/packages/effect-bun-test/__tests__/command.test.ts b/packages/effect-bun-test/__tests__/command.test.ts
new file mode 100644
index 0000000..72dffbc
--- /dev/null
+++ b/packages/effect-bun-test/__tests__/command.test.ts
@@ -0,0 +1,208 @@
+import { Effect, Exit, Layer } from 'effect';
+import { ChildProcess, ChildProcessSpawner } from 'effect/unstable/process';
+import {
+  argv,
+  commandArgv,
+  commandExecutorLayer,
+  commandLine,
+  ScriptedCommandExecutor,
+  ScriptedProcess,
+  TestCommandExecutor,
+} from '../src/command';
+import { describe, expect, it } from '../src/index';
+
+const spawner = ChildProcessSpawner.ChildProcessSpawner;
+
+// v4's array form takes the arguments as one array; v3's `Command.make` was
+// variadic. Every command below goes through this helper so the difference is
+// stated once.
+const cmd = (command: string, ...args: ReadonlyArray<string>) => ChildProcess.make(command, [...args]);
+
+describe('commandArgv / commandLine', () => {
+  it('flattens a StandardCommand into its argv', () => {
+    // A v4 `Command` is itself an `Effect`, so these read in pipe style: the
+    // Effect language service rejects `commandArgv(command)` as a missed
+    // pipeable opportunity.
+    expect(cmd('git', 'status', '--short').pipe(commandArgv)).toEqual(['git', 'status', '--short']);
+    expect(cmd('git', 'status').pipe(commandLine)).toBe('git status');
+  });
+
+  it('a command with no arguments is just the executable', () => {
+    expect(cmd('ls').pipe(commandArgv)).toEqual(['ls']);
+  });
+});
+
+describe('argv matchers', () => {
+  it('exact matches only the whole argv', () => {
+    const m = argv.exact('git', 'status');
+    expect(m.matches(['git', 'status'])).toBe(true);
+    expect(m.matches(['git', 'status', '--short'])).toBe(false);
+    expect(m.matches(['git'])).toBe(false);
+  });
+
+  it('prefix ignores trailing arguments', () => {
+    const m = argv.prefix('git', 'status');
+    expect(m.matches(['git', 'status', '--short'])).toBe(true);
+    expect(m.matches(['git', 'log'])).toBe(false);
+  });
+
+  it('matching wraps an arbitrary predicate', () => {
+    const m = argv.matching((a) => a.includes('--json'), 'json flag');
+    expect(m.matches(['x', '--json'])).toBe(true);
+    expect(m.matches(['x'])).toBe(false);
+    expect(m.describe).toContain('json flag');
+  });
+});
+
+describe('TestCommandExecutor', () => {
+  it.effect('serves the scripted exit code and stdout', () =>
+    Effect.gen(function* () {
+      const s = yield* spawner;
+      // `exitCode` is a branded number in v4; widening keeps `toBe` comparable.
+      const code: number = yield* s.exitCode(cmd('anything'));
+      expect(code).toBe(7);
+      expect(yield* s.string(cmd('anything'))).toBe('scripted-out');
+    }).pipe(Effect.provide(TestCommandExecutor(() => ({ exitCode: 7, stdout: 'scripted-out' })))),
+  );
+
+  it.effect('the script sees the argv it was called with', () =>
+    Effect.gen(function* () {
+      const s = yield* spawner;
+      expect(yield* s.string(cmd('echo', 'hello'))).toBe('echo hello');
+    }).pipe(Effect.provide(TestCommandExecutor((c) => ({ stdout: commandLine(c) })))),
+  );
+
+  // `string` reads stdout alone; `all` is the interleaved stream, and the v4
+  // handle gained it as a required member. Reading it proves the double does
+  // not simply return an empty stream there.
+  it.effect('`all` carries stdout followed by stderr', () =>
+    Effect.gen(function* () {
+      const s = yield* spawner;
+      const c = cmd('x');
+      expect(yield* s.string(c)).toBe('OUT');
+      expect(yield* s.string(c, { includeStderr: true })).toBe('OUTERR');
+    }).pipe(Effect.provide(TestCommandExecutor(() => ({ stdout: 'OUT', stderr: 'ERR' })))),
+  );
+
+  it.effect('an exit code the script omits defaults to 0', () =>
+    Effect.gen(function* () {
+      const s = yield* spawner;
+      const code: number = yield* s.exitCode(cmd('x'));
+      expect(code).toBe(0);
+    }).pipe(Effect.provide(TestCommandExecutor(() => ({})))),
+  );
+});
+
+describe('ScriptedCommandExecutor', () => {
+  it.effect('serves an expectation whose argv matcher accepts the spawn', () =>
+    Effect.gen(function* () {
+      const s = yield* spawner;
+      expect(yield* s.string(cmd('git', 'status'))).toBe('on branch main');
+      const code: number = yield* s.exitCode(cmd('git', 'push'));
+      expect(code).toBe(3);
+    }).pipe(
+      Effect.provide(
+        ScriptedCommandExecutor([
+          { argv: ['git', 'status'], stdout: 'on branch main' },
+          { argv: ['git', 'push'], exitCode: 3 },
+        ]),
+      ),
+    ),
+  );
+
+  // Two separate guarantees, and the second is easy to lose: the rejection
+  // reaches the caller as a TYPED PlatformError (so `catch` sees it, not just
+  // `catchDefect`), and the violation is ALSO replayed when the layer's scope
+  // closes — so a test that swallowed the error still fails rather than
+  // passing on a subprocess that was never scripted.
+  it.effect('an unmatched spawn is a typed failure AND fails the scope on close', () =>
+    Effect.gen(function* () {
+      let caught = 'never-ran';
+      const exit = yield* Effect.exit(
+        Effect.gen(function* () {
+          const s = yield* spawner;
+          yield* s.exitCode(cmd('rm', '-rf')).pipe(
+            Effect.catch((e) =>
+              Effect.sync(() => {
+                caught = String(e);
+              }),
+            ),
+          );
+        }).pipe(Effect.provide(ScriptedCommandExecutor([{ argv: ['git', 'status'] }]))),
+      );
+
+      // `Effect.catch` only sees the typed error channel.
+      expect(caught).toContain('unexpected spawn');
+      expect(caught).toContain('rm');
+
+      expect(Exit.isFailure(exit)).toBe(true);
+      expect(Exit.isFailure(exit) ? String(exit.cause) : '').toContain('rm');
+    }),
+  );
+
+  it.effect('a predicate matcher selects the expectation', () =>
+    Effect.gen(function* () {
+      const s = yield* spawner;
+      expect(yield* s.string(cmd('tool', '--json', 'x'))).toBe('{}');
+    }).pipe(Effect.provide(ScriptedCommandExecutor([{ argv: (a) => a.includes('--json'), stdout: '{}' }]))),
+  );
+});
+
+describe('ScriptedProcess exhaustion', () => {
+  it('assertExhausted throws while an expectation is unconsumed', () => {
+    const builder = ScriptedProcess([{ argv: ['a'] }, { argv: ['b'] }]);
+    builder.next(['a']);
+    expect(() => builder.assertExhausted()).toThrow(/b/);
+  });
+
+  it('assertExhausted is silent once every expectation is consumed', () => {
+    const builder = ScriptedProcess([{ argv: ['a'] }]);
+    builder.next(['a']);
+    expect(() => builder.assertExhausted()).not.toThrow();
+  });
+
+  it('allowUnconsumed tolerates a leftover expectation', () => {
+    const builder = ScriptedProcess([{ argv: ['a'] }, { argv: ['b'] }], { allowUnconsumed: true });
+    builder.next(['a']);
+    expect(() => builder.assertExhausted()).not.toThrow();
+  });
+
+  it('records each call and its outcome', () => {
+    const builder = ScriptedProcess([{ argv: ['a'] }]);
+    builder.next(['a']);
+    expect(builder.calls).toEqual([['a']]);
+    expect(builder.log[0]?.outcome).toBe('consumed');
+  });
+
+  // `commandExecutorLayer` registers a finalizer, so an unconsumed expectation
+  // has to surface when the layer's scope closes rather than passing silently.
+  it.effect('an unconsumed expectation becomes a defect when the layer scope closes', () =>
+    Effect.gen(function* () {
+      const builder = ScriptedProcess([{ argv: ['never-run'] }]);
+      const exit = yield* Effect.exit(Effect.void.pipe(Effect.provide(commandExecutorLayer(builder))));
+
+      expect(Exit.isFailure(exit)).toBe(true);
+      expect(Exit.isFailure(exit) ? String(exit.cause) : '').toContain('never-run');
+    }),
+  );
+
+  it.effect('a fully consumed script closes its scope cleanly', () =>
+    Effect.gen(function* () {
+      const builder = ScriptedProcess([{ argv: ['git'] }]);
+      const exit = yield* Effect.exit(
+        Effect.gen(function* () {
+          const s = yield* spawner;
+          yield* s.exitCode(cmd('git'));
+        }).pipe(Effect.provide(commandExecutorLayer(builder))),
+      );
+
+      expect(Exit.isSuccess(exit)).toBe(true);
+    }),
+  );
+});
+
+describe('layer wiring', () => {
+  it('TestCommandExecutor produces a Layer providing the spawner', () => {
+    expect(Layer.isLayer(TestCommandExecutor(() => ({})))).toBe(true);
+  });
+});
diff --git a/packages/effect-bun-test/__tests__/log-capture.test.ts b/packages/effect-bun-test/__tests__/log-capture.test.ts
index 59611b0..9455130 100644
--- a/packages/effect-bun-test/__tests__/log-capture.test.ts
+++ b/packages/effect-bun-test/__tests__/log-capture.test.ts
@@ -1,6 +1,6 @@
 import { DateTime, Effect, Logger, References } from 'effect';
 import { describe, expect, it } from '../src/index';
-import { makeLogCapture, renderLogMessage } from '../src/log-capture';
+import { logLevelLabel, makeLogCapture, renderLogMessage } from '../src/log-capture';
 
 const LF = String.fromCharCode(10);
 const CR = String.fromCharCode(13);
@@ -136,11 +136,26 @@ describe('makeLogCapture — end-to-end through the real Effect logger', () => {
     Effect.gen(function* () {
       const cap = makeLogCapture();
       yield* Effect.logWarning('warn-here').pipe(Effect.provide(cap.layer));
-      expect(cap.entries[0]?.level).toBe('Warn');
+      expect(cap.entries[0]?.level).toBe('WARN');
       expect(cap.entries[0]?.message).toContain('warn-here');
     }),
   );
 
+  // v4 renamed every level ('WARN' -> 'Warn') and respelled the off sentinel
+  // ('OFF' -> 'None'). A caller's `level === 'WARN'` filter would go silently
+  // empty rather than fail, so the captured level stays on the v3 labels.
+  it.live('reports levels under their v3 labels, not the raw v4 level names', () =>
+    Effect.gen(function* () {
+      const cap = makeLogCapture();
+      yield* Effect.logError('e').pipe(
+        Effect.andThen(Effect.logWarning('w')),
+        Effect.andThen(Effect.logInfo('i')),
+        Effect.andThen(Effect.logDebug('d')),
+        Effect.provide(cap.layer),
+      );
+      expect(cap.entries.map((e) => e.level)).toEqual(['ERROR', 'WARN', 'INFO', 'DEBUG']);
+    }),
+  );
   it.live('exposes the untouched payload on `raw` for structural assertions', () =>
     Effect.gen(function* () {
       const cap = makeLogCapture();
@@ -236,3 +251,22 @@ describe('makeLogCapture — end-to-end through the real Effect logger', () => {
     }),
   );
 });
+
+describe('logLevelLabel', () => {
+  it('maps a v4 level name onto the v3 label', () => {
+    expect(logLevelLabel('Fatal')).toBe('FATAL');
+    expect(logLevelLabel('Error')).toBe('ERROR');
+    expect(logLevelLabel('Warn')).toBe('WARN');
+    expect(logLevelLabel('Info')).toBe('INFO');
+    expect(logLevelLabel('Debug')).toBe('DEBUG');
+    expect(logLevelLabel('Trace')).toBe('TRACE');
+  });
+
+  // 'All' upper-cases to the right answer by luck; 'None' does not, and v3
+  // called that level 'OFF'. Both are pinned so the table cannot rot into a
+  // bare `toUpperCase()`.
+  it('respells the sentinels, which a plain upper-casing gets wrong', () => {
+    expect(logLevelLabel('All')).toBe('ALL');
+    expect(logLevelLabel('None')).toBe('OFF');
+  });
+});
diff --git a/packages/effect-bun-test/__tests__/prop.test.ts b/packages/effect-bun-test/__tests__/prop.test.ts
new file mode 100644
index 0000000..b3e8d32
--- /dev/null
+++ b/packages/effect-bun-test/__tests__/prop.test.ts
@@ -0,0 +1,71 @@
+import { Effect, Schema } from 'effect';
+import * as fc from 'effect/testing/FastCheck';
+import { describe, expect, it } from '../src/index';
+
+// v4 deleted the standalone `Arbitrary` module and reshaped `Schema`, so every
+// `prop` form goes through a rewritten schema-to-arbitrary bridge. None of it
+// is visible to `tsc`: a bridge that silently produced `undefined` for every
+// case would still typecheck, and a property body that never ran would still
+// report as a passing test.
+
+describe('prop — array form', () => {
+  it.prop('derives values from a Schema', [Schema.String, Schema.Number], ([s, n]) => {
+    expect(typeof s).toBe('string');
+    expect(typeof n).toBe('number');
+  });
+
+  it.prop('accepts a raw FastCheck arbitrary', [fc.constant('fixed')], ([s]) => {
+    expect(s).toBe('fixed');
+  });
+
+  it.prop('mixes a Schema and a raw arbitrary in one list', [Schema.String, fc.constant(42)], ([s, n]) => {
+    expect(typeof s).toBe('string');
+    expect(n).toBe(42);
+  });
+});
+
+describe('prop — record form', () => {
+  it.prop('derives values from a Schema', { name: Schema.String, age: Schema.Number }, ({ name, age }) => {
+    expect(typeof name).toBe('string');
+    expect(typeof age).toBe('number');
+  });
+
+  it.prop(
+    'derives a composite Schema, not just the scalars',
+    { point: Schema.Struct({ x: Schema.Number, y: Schema.Number }), flag: Schema.Boolean },
+    ({ point, flag }) => {
+      expect(typeof point.x).toBe('number');
+      expect(typeof point.y).toBe('number');
+      expect(typeof flag).toBe('boolean');
+    },
+  );
+});
+
+describe('prop — Effect-returning forms', () => {
+  it.effect.prop('it.effect.prop runs the body as an Effect', { s: Schema.String }, ({ s }) =>
+    Effect.sync(() => {
+      expect(typeof s).toBe('string');
+    }),
+  );
+
+  it.live.prop('it.live.prop runs the body as an Effect', { n: Schema.Number }, ({ n }) =>
+    Effect.sync(() => {
+      expect(typeof n).toBe('number');
+    }),
+  );
+});
+
+// A property whose body never executes is the failure mode `tsc` cannot see,
+// so one case counts its own invocations and asserts the count moved.
+describe('prop actually runs the body', () => {
+  let runs = 0;
+
+  it.prop('the body is invoked once per generated case', [Schema.String], ([s]) => {
+    expect(typeof s).toBe('string');
+    runs += 1;
+  });
+
+  it('the counter proves the property body ran', () => {
+    expect(runs).toBeGreaterThan(1);
+  });
+});
diff --git a/packages/effect-bun-test/src/log-capture.ts b/packages/effect-bun-test/src/log-capture.ts
index 5de3cbf..f01962c 100644
--- a/packages/effect-bun-test/src/log-capture.ts
+++ b/packages/effect-bun-test/src/log-capture.ts
@@ -82,6 +82,18 @@ export type LogCaptureOptions = {
   readonly minimumLogLevel?: MinimumLogLevel;
 };
 
+// v3 exposed a log level as an object whose `label` was upper case ('WARN',
+// 'INFO', and 'OFF' for the off sentinel); v4 models a level as a bare string
+// union member ('Warn', 'Info', 'None'). Every level differs in case and the
+// off sentinel differs in spelling, so a caller that kept v3's
+// `level === 'WARN'` comparison would not fail — it would match nothing and
+// quietly assert nothing. `CapturedLog.level` therefore stays on the v3 labels,
+// and this mapping is exported so a caller that builds its own capture logger
+// can label a raw v4 level the same way.
+const LOG_LEVEL_LABEL: Readonly<Record<string, string>> = { All: 'ALL', None: 'OFF' };
+
+export const logLevelLabel = (level: string): string => LOG_LEVEL_LABEL[level] ?? level.toUpperCase();
+
 const withMinimumLogLevel = (base: Layer.Layer<never>, level: MinimumLogLevel): Layer.Layer<never> =>
   level === LEAVE_AMBIENT_LOG_LEVEL
     ? base
@@ -102,7 +114,7 @@ const replaceDefaultLogger = (logger: Logger.Logger<unknown, void>): Layer.Layer
 export const makeLogCapture = (options: LogCaptureOptions = {}): LogCapture => {
   const entries: CapturedLog[] = [];
   const logger = Logger.make(({ logLevel, message }) => {
-    entries.push({ level: logLevel, message: renderLogMessage(message), raw: message });
+    entries.push({ level: logLevelLabel(logLevel), message: renderLogMessage(message), raw: message });
   });
   // v4 removed `Logger.add` / `Logger.replace`. `add` maps cleanly onto
   // `mergeWithExisting`, but `replace` does not: `Logger.layer([logger])` would