Add workspace export and baseline diff

Complete the 2.6.0 workspace milestone by adding explicit host-out export and immutable-baseline diff across the CLI, Python SDK, and MCP server.

Capture a baseline archive at workspace creation, export live /workspace paths through the guest agent, and compute structured whole-workspace diffs on the host without affecting command logs or shell state. The docs, roadmap, bundled guest agent, and workspace example now reflect the new create -> sync -> diff -> export workflow.

Validation: uv lock, UV_CACHE_DIR=.uv-cache make check, UV_CACHE_DIR=.uv-cache make dist-check, and a real guest-backed Firecracker smoke covering workspace create, sync push, diff, export, and delete.

tests/test_cli.py

@@ -64,6 +64,8 @@ def test_cli_subcommand_help_includes_examples_and_guidance() -> None:
     assert "pyro workspace create debian:12 --seed-path ./repo" in workspace_help
     assert "pyro workspace sync push WORKSPACE_ID ./repo --dest src" in workspace_help
     assert "pyro workspace exec WORKSPACE_ID" in workspace_help
+    assert "pyro workspace diff WORKSPACE_ID" in workspace_help
+    assert "pyro workspace export WORKSPACE_ID src/note.txt --output ./note.txt" in workspace_help
     assert "pyro workspace shell open WORKSPACE_ID" in workspace_help
 
     workspace_create_help = _subparser_choice(
@@ -93,6 +95,18 @@ def test_cli_subcommand_help_includes_examples_and_guidance() -> None:
     assert "--dest" in workspace_sync_push_help
     assert "Import host content into `/workspace`" in workspace_sync_push_help
 
+    workspace_export_help = _subparser_choice(
+        _subparser_choice(parser, "workspace"), "export"
+    ).format_help()
+    assert "--output" in workspace_export_help
+    assert "Export one file or directory from `/workspace`" in workspace_export_help
+
+    workspace_diff_help = _subparser_choice(
+        _subparser_choice(parser, "workspace"), "diff"
+    ).format_help()
+    assert "immutable workspace baseline" in workspace_diff_help
+    assert "workspace export" in workspace_diff_help
+
     workspace_shell_help = _subparser_choice(
         _subparser_choice(parser, "workspace"),
         "shell",
@@ -522,6 +536,100 @@ def test_cli_workspace_exec_prints_human_output(
     )
 
 
+def test_cli_workspace_export_prints_human_output(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    class StubPyro:
+        def export_workspace(
+            self,
+            workspace_id: str,
+            path: str,
+            *,
+            output_path: str,
+        ) -> dict[str, Any]:
+            assert workspace_id == "workspace-123"
+            assert path == "note.txt"
+            assert output_path == "./note.txt"
+            return {
+                "workspace_id": workspace_id,
+                "workspace_path": "/workspace/note.txt",
+                "output_path": "/tmp/note.txt",
+                "artifact_type": "file",
+                "entry_count": 1,
+                "bytes_written": 6,
+                "execution_mode": "guest_vsock",
+            }
+
+    class StubParser:
+        def parse_args(self) -> argparse.Namespace:
+            return argparse.Namespace(
+                command="workspace",
+                workspace_command="export",
+                workspace_id="workspace-123",
+                path="note.txt",
+                output="./note.txt",
+                json=False,
+            )
+
+    monkeypatch.setattr(cli, "_build_parser", lambda: StubParser())
+    monkeypatch.setattr(cli, "Pyro", StubPyro)
+    cli.main()
+    output = capsys.readouterr().out
+    assert "[workspace-export] workspace_id=workspace-123" in output
+    assert "artifact_type=file" in output
+
+
+def test_cli_workspace_diff_prints_human_output(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    class StubPyro:
+        def diff_workspace(self, workspace_id: str) -> dict[str, Any]:
+            assert workspace_id == "workspace-123"
+            return {
+                "workspace_id": workspace_id,
+                "changed": True,
+                "summary": {
+                    "total": 1,
+                    "added": 0,
+                    "modified": 1,
+                    "deleted": 0,
+                    "type_changed": 0,
+                    "text_patched": 1,
+                    "non_text": 0,
+                },
+                "entries": [
+                    {
+                        "path": "note.txt",
+                        "status": "modified",
+                        "artifact_type": "file",
+                        "text_patch": "--- a/note.txt\n+++ b/note.txt\n",
+                    }
+                ],
+                "patch": "--- a/note.txt\n+++ b/note.txt\n",
+            }
+
+    class StubParser:
+        def parse_args(self) -> argparse.Namespace:
+            return argparse.Namespace(
+                command="workspace",
+                workspace_command="diff",
+                workspace_id="workspace-123",
+                json=False,
+            )
+
+    monkeypatch.setattr(cli, "_build_parser", lambda: StubParser())
+    monkeypatch.setattr(cli, "Pyro", StubPyro)
+    cli.main()
+    output = capsys.readouterr().out
+    assert (
+        "[workspace-diff] workspace_id=workspace-123 total=1 added=0 modified=1"
+        in output
+    )
+    assert "--- a/note.txt" in output
+
+
 def test_cli_workspace_sync_push_prints_json(
     monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]
 ) -> None: