fix: backfill base_url on migration so pre-base_url entries still load

async_setup_entry does entry.data[CONF_BASE_URL] as a hard index, but
base_url is this fork's own addition: an entry created by a build from
before the base_url commits (48195c9 era, version 2 minor 7) has no such
key. On restart, setup raises KeyError: 'base_url' and the integration
fails to load -- reproduced in test first, where async_setup returns
False with that KeyError in the log.

Fixed with a migration step rather than a defensive .get(), matching the
pattern the rest of async_migrate_entry already uses, so the invariant
"a loaded entry has base_url" holds for every caller instead of each
call site guarding itself:

- new step 2.7 -> 2.8 backfills DEFAULT_BASE_URL via dict.setdefault, so
  an entry that already has a base_url keeps its own endpoint and only a
  missing one is filled. An install from before this feature was
  implicitly using api.openai.com, which is exactly DEFAULT_BASE_URL, so
  the backfill preserves existing behavior rather than repointing anyone.
- config_flow MINOR_VERSION 7 -> 8, otherwise the step never runs.

test_client_built_with_base_url now also covers the preserve path, since
its entry starts at minor 7 with a base_url set and must still reach the
client unchanged after migrating.

Also updated test_form's `minor_version == 7` assertion to 8; it pins
the version new entries are created at, so the bump is expected. The
reauth test's MockConfigEntry stays at minor 7 on purpose -- it stands
in for an already-existing entry.

Local: 138 passed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NxJYWgGJtCw13qUHZtG8ki

tests/test_base_url.py

@@ -5,7 +5,11 @@ from unittest.mock import AsyncMock, patch
 from homeassistant.core import HomeAssistant
 from pytest_homeassistant_custom_component.common import MockConfigEntry
 
-from custom_components.openai_compatible.const import CONF_BASE_URL, DOMAIN
+from custom_components.openai_compatible.const import (
+    CONF_BASE_URL,
+    DEFAULT_BASE_URL,
+    DOMAIN,
+)
 
 
 async def test_client_built_with_base_url(hass: HomeAssistant) -> None:
@@ -48,3 +52,31 @@ async def test_api_key_optional(hass: HomeAssistant) -> None:
         await hass.async_block_till_done()
 
     assert mock_client.call_args.kwargs["api_key"] == "not-required"
+
+
+async def test_migration_backfills_missing_base_url(hass: HomeAssistant) -> None:
+    """An entry stored before base_url existed must still set up.
+
+    Entries written by an earlier build of this fork have no base_url key at
+    all, so anything that indexes entry.data[CONF_BASE_URL] raises KeyError
+    and the integration fails to load on restart.
+    """
+    entry = MockConfigEntry(
+        domain=DOMAIN,
+        data={"api_key": "sk-test"},
+        version=2,
+        minor_version=7,
+    )
+    entry.add_to_hass(hass)
+
+    with patch(
+        "custom_components.openai_compatible.openai.AsyncOpenAI"
+    ) as mock_client:
+        mock_client.return_value.platform_headers = lambda: {}
+        mock_client.return_value.with_options.return_value.models.list = AsyncMock()
+        assert await hass.config_entries.async_setup(entry.entry_id)
+        await hass.async_block_till_done()
+
+    assert entry.data[CONF_BASE_URL] == DEFAULT_BASE_URL
+    assert entry.minor_version == 8
+    assert mock_client.call_args.kwargs["base_url"] == DEFAULT_BASE_URL

tests/test_config_flow.py

@@ -122,7 +122,7 @@ async def test_form(hass: HomeAssistant) -> None:
         },
     ]
     assert result2["version"] == 2
-    assert result2["minor_version"] == 7
+    assert result2["minor_version"] == 8
     assert len(mock_setup_entry.mock_calls) == 1