Add Claude Code as default platform when none detected

When `deepwork install` is run and no platforms are detected,
automatically create the `.claude` directory and add it to the
platforms list instead of failing with an error.

Author: claude

src/deepwork/cli/install.py

@@ -283,21 +283,25 @@ def _install_deepwork(platform_name: str | None, project_path: Path) -> None:
         available_adapters = detector.detect_all_platforms()
 
         if not available_adapters:
-            supported = ", ".join(
-                f"{AgentAdapter.get(name).display_name} ({AgentAdapter.get(name).config_dir}/)"
-                for name in AgentAdapter.list_names()
-            )
-            raise InstallError(
-                f"No AI platform detected.\n"
-                f"DeepWork supports: {supported}.\n"
-                "Please set up one of these platforms first, or use --platform to specify."
-            )
-
-        # Add all detected platforms
-        for adapter in available_adapters:
-            console.print(f"  [green]✓[/green] {adapter.display_name} detected")
-            platforms_to_add.append(adapter.name)
-        detected_adapters = available_adapters
+            # No platforms detected - default to Claude Code
+            console.print("  [dim]•[/dim] No AI platform detected, defaulting to Claude Code")
+
+            # Create .claude directory
+            claude_dir = project_path / ".claude"
+            ensure_dir(claude_dir)
+            console.print(f"  [green]✓[/green] Created {claude_dir.relative_to(project_path)}/")
+
+            # Get Claude adapter
+            claude_adapter_class = AgentAdapter.get("claude")
+            claude_adapter = claude_adapter_class(project_root=project_path)
+            platforms_to_add = [claude_adapter.name]
+            detected_adapters = [claude_adapter]
+        else:
+            # Add all detected platforms
+            for adapter in available_adapters:
+                console.print(f"  [green]✓[/green] {adapter.display_name} detected")
+                platforms_to_add.append(adapter.name)
+            detected_adapters = available_adapters
 
     # Step 3: Create .deepwork/ directory structure
     console.print("[yellow]→[/yellow] Creating DeepWork directory structure...")

tests/integration/test_install_flow.py

@@ -79,14 +79,32 @@ def test_install_fails_without_git(self, temp_dir: Path) -> None:
         assert result.exit_code != 0
         assert "Not a Git repository" in result.output
 
-    def test_install_fails_without_platform(self, mock_git_repo: Path) -> None:
-        """Test that install fails when no platform is detected."""
+    def test_install_defaults_to_claude_when_no_platform(self, mock_git_repo: Path) -> None:
+        """Test that install defaults to Claude Code when no platform is detected."""
         runner = CliRunner()
 
-        result = runner.invoke(cli, ["install", "--path", str(mock_git_repo)])
+        result = runner.invoke(
+            cli, ["install", "--path", str(mock_git_repo)], catch_exceptions=False
+        )
 
-        assert result.exit_code != 0
-        assert "No AI platform detected" in result.output
+        assert result.exit_code == 0
+        assert "No AI platform detected, defaulting to Claude Code" in result.output
+        assert "Created .claude/" in result.output
+        assert "DeepWork installed successfully for Claude Code" in result.output
+
+        # Verify .claude directory was created
+        claude_dir = mock_git_repo / ".claude"
+        assert claude_dir.exists()
+
+        # Verify config.yml has Claude
+        config_file = mock_git_repo / ".deepwork" / "config.yml"
+        config = load_yaml(config_file)
+        assert config is not None
+        assert "claude" in config["platforms"]
+
+        # Verify skills were created for Claude
+        skills_dir = claude_dir / "skills"
+        assert (skills_dir / "deepwork_jobs" / "SKILL.md").exists()
 
     def test_install_with_multiple_platforms_auto_detect(
         self, mock_multi_platform_project: Path