fix(onboard): require explicit save in interactive wizard

Cherry-pick from d6acf1a with manual merge resolution.
Keep onboarding edits in draft state until users choose Done or Save and
Exit, so backing out or discarding the wizard no longer persists partial
changes.

Co-Authored-By: Jason Zhao <144443939+JasonZhaoWW@users.noreply.github.com>

tests/test_onboard_logic.py

@@ -7,18 +7,24 @@ without testing the interactive UI components.
 import json
 from pathlib import Path
 from types import SimpleNamespace
-from typing import Any
+from typing import Any, cast
 
 import pytest
 from pydantic import BaseModel, Field
 
+from nanobot.cli import onboard_wizard
+
 # Import functions to test
 from nanobot.cli.commands import _merge_missing_defaults
 from nanobot.cli.onboard_wizard import (
+    _BACK_PRESSED,
+    _configure_pydantic_model,
     _format_value,
     _get_field_display_name,
     _get_field_type_info,
+    run_onboard,
 )
+from nanobot.config.schema import Config
 from nanobot.utils.helpers import sync_workspace_templates
 
 
@@ -371,3 +377,116 @@ class TestProviderChannelInfo:
         for provider_name, value in info.items():
             assert isinstance(value, tuple)
             assert len(value) == 4  # (display_name, needs_api_key, needs_api_base, env_var)
+
+
+class _SimpleDraftModel(BaseModel):
+    api_key: str = ""
+
+
+class _NestedDraftModel(BaseModel):
+    api_key: str = ""
+
+
+class _OuterDraftModel(BaseModel):
+    nested: _NestedDraftModel = Field(default_factory=_NestedDraftModel)
+
+
+class TestConfigurePydanticModelDrafts:
+    @staticmethod
+    def _patch_prompt_helpers(monkeypatch, tokens, text_value="secret"):
+        sequence = iter(tokens)
+
+        def fake_select(_prompt, choices, default=None):
+            token = next(sequence)
+            if token == "first":
+                return choices[0]
+            if token == "done":
+                return "✓ Done"
+            if token == "back":
+                return _BACK_PRESSED
+            return token
+
+        monkeypatch.setattr(onboard_wizard, "_select_with_back", fake_select)
+        monkeypatch.setattr(onboard_wizard, "_show_config_panel", lambda *_args, **_kwargs: None)
+        monkeypatch.setattr(
+            onboard_wizard, "_input_with_existing", lambda *_args, **_kwargs: text_value
+        )
+
+    def test_discarding_section_keeps_original_model_unchanged(self, monkeypatch):
+        model = _SimpleDraftModel()
+        self._patch_prompt_helpers(monkeypatch, ["first", "back"])
+
+        result = _configure_pydantic_model(model, "Simple")
+
+        assert result is None
+        assert model.api_key == ""
+
+    def test_completing_section_returns_updated_draft(self, monkeypatch):
+        model = _SimpleDraftModel()
+        self._patch_prompt_helpers(monkeypatch, ["first", "done"])
+
+        result = _configure_pydantic_model(model, "Simple")
+
+        assert result is not None
+        updated = cast(_SimpleDraftModel, result)
+        assert updated.api_key == "secret"
+        assert model.api_key == ""
+
+    def test_nested_section_back_discards_nested_edits(self, monkeypatch):
+        model = _OuterDraftModel()
+        self._patch_prompt_helpers(monkeypatch, ["first", "first", "back", "done"])
+
+        result = _configure_pydantic_model(model, "Outer")
+
+        assert result is not None
+        updated = cast(_OuterDraftModel, result)
+        assert updated.nested.api_key == ""
+        assert model.nested.api_key == ""
+
+    def test_nested_section_done_commits_nested_edits(self, monkeypatch):
+        model = _OuterDraftModel()
+        self._patch_prompt_helpers(monkeypatch, ["first", "first", "done", "done"])
+
+        result = _configure_pydantic_model(model, "Outer")
+
+        assert result is not None
+        updated = cast(_OuterDraftModel, result)
+        assert updated.nested.api_key == "secret"
+        assert model.nested.api_key == ""
+
+
+class TestRunOnboardExitBehavior:
+    def test_main_menu_interrupt_can_discard_unsaved_session_changes(self, monkeypatch):
+        initial_config = Config()
+
+        responses = iter(
+            [
+                "🤖 Configure Agent Settings",
+                KeyboardInterrupt(),
+                "🗑️ Exit Without Saving",
+            ]
+        )
+
+        class FakePrompt:
+            def __init__(self, response):
+                self.response = response
+
+            def ask(self):
+                if isinstance(self.response, BaseException):
+                    raise self.response
+                return self.response
+
+        def fake_select(*_args, **_kwargs):
+            return FakePrompt(next(responses))
+
+        def fake_configure_agents(config):
+            config.agents.defaults.model = "test/provider-model"
+
+        monkeypatch.setattr(onboard_wizard, "_show_main_menu_header", lambda: None)
+        monkeypatch.setattr(onboard_wizard.questionary, "select", fake_select)
+        monkeypatch.setattr(onboard_wizard, "_configure_agents", fake_configure_agents)
+
+        result = run_onboard(initial_config=initial_config)
+
+        assert result.should_save is False
+        assert result.config.model_dump(by_alias=True) == initial_config.model_dump(by_alias=True)