test(cli): tighten and relocate --format=json validation test

Move the --format=json-requires-dry-run check out of the integration
suite (it doesn't need Docker — argparse fails before any backend
runs) and tighten the assertion: previously asserted only that exit
code was nonzero, so any unrelated breakage (manifest resolution
failure, bad agent name, etc.) silently passed. Now asserts stderr
contains the actual flag-conflict message.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/integration/test_dry_run_plan.py

@@ -78,34 +78,6 @@ class TestDryRunPlan(unittest.TestCase):
             import shutil
             shutil.rmtree(work_dir, ignore_errors=True)
 
-    def test_json_format_requires_dry_run(self):
-        """The CLI rejects --format=json without --dry-run; emitting JSON
-        in a real run would race the y/N prompt."""
-        work_dir = Path(tempfile.mkdtemp())
-        try:
-            manifest = work_dir / "claude-bottle.json"
-            manifest.write_text(json.dumps({
-                "bottles": {"dev": {}},
-                "agents": {"demo": {"skills": [], "prompt": "", "bottle": "dev"}},
-            }))
-            env = os.environ.copy()
-            env["HOME"] = str(work_dir)
-            env.pop("CLAUDE_BOTTLE_DRY_RUN", None)
-            result = subprocess.run(
-                [
-                    sys.executable, str(REPO_ROOT / "cli.py"),
-                    "start", "--format", "json", "demo",
-                ],
-                cwd=work_dir,
-                env=env,
-                capture_output=True,
-                text=True,
-            )
-            self.assertNotEqual(0, result.returncode)
-        finally:
-            import shutil
-            shutil.rmtree(work_dir, ignore_errors=True)
-
     def _count_claude_bottle_networks(self) -> int:
         result = subprocess.run(
             ["docker", "network", "ls", "--format", "{{.Name}}"],

tests/unit/test_cli_start_format.py

@@ -0,0 +1,53 @@
+"""Unit: argparse-level CLI checks for `start --format`.
+
+Lives in tests/unit/ because nothing here touches Docker — the CLI
+exits at argument-validation time before any backend code runs.
+"""
+
+import json
+import os
+import subprocess
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parent.parent.parent
+
+
+class TestStartFormatFlag(unittest.TestCase):
+    def test_json_format_requires_dry_run(self):
+        """Emitting JSON in a real run would race the y/N prompt; the
+        CLI must reject the combination with a message that names the
+        offending flag."""
+        work_dir = Path(tempfile.mkdtemp())
+        try:
+            (work_dir / "claude-bottle.json").write_text(json.dumps({
+                "bottles": {"dev": {}},
+                "agents": {"demo": {"skills": [], "prompt": "", "bottle": "dev"}},
+            }))
+            env = os.environ.copy()
+            env["HOME"] = str(work_dir)
+            env.pop("CLAUDE_BOTTLE_DRY_RUN", None)
+            result = subprocess.run(
+                [
+                    sys.executable, str(REPO_ROOT / "cli.py"),
+                    "start", "--format", "json", "demo",
+                ],
+                cwd=work_dir,
+                env=env,
+                capture_output=True,
+                text=True,
+            )
+            self.assertNotEqual(0, result.returncode)
+            self.assertIn(
+                "--format=json requires --dry-run", result.stderr,
+                f"expected the flag-conflict message; got stderr={result.stderr!r}",
+            )
+        finally:
+            import shutil
+            shutil.rmtree(work_dir, ignore_errors=True)
+
+
+if __name__ == "__main__":
+    unittest.main()