Ensure live provider checks reach the provider

Accept Docker Compose's exact string representation of the fixed 1024-dimensional embedding contract while rejecting every widened or ambiguous value. Entry-level smoke tests now exercise the same environment shape used by the container.

Constraint: The current local Bailian credential still returns 401 for all three capabilities and is not stored in Git.
Rejected: Change the field to an unconstrained integer | would allow a runtime dimension that disagrees with vector(1024).
Confidence: high
Scope-risk: narrow
Directive: Keep the database vector dimension and provider dimension locked together through an ADR-backed migration.
Tested: make verify; 75 backend tests; 14 frontend tests; rebuilt provider-smoke image; normal Compose smoke reached all three provider endpoints.
Not-tested: Successful live provider response remains blocked by external authentication.

backend/app/core/config.py

@@ -71,6 +71,16 @@ class Settings(BaseSettings):
     def normalize_base_url(cls, value: str) -> str:
         return value.rstrip("/")
 
+    @field_validator("embedding_dimension", mode="before")
+    @classmethod
+    def parse_embedding_dimension(cls, value: object) -> int:
+        """Accept Compose's string representation without widening the contract."""
+        if value == "1024" or (
+            isinstance(value, int) and not isinstance(value, bool) and value == 1024
+        ):
+            return 1024
+        raise ValueError("EMBEDDING_DIMENSION must be exactly 1024")
+
     @model_validator(mode="after")
     def validate_rag_limits(self) -> Self:
         if self.chunk_overlap_tokens >= self.chunk_target_tokens:

backend/tests/unit/test_config_and_secrets.py

@@ -46,6 +46,32 @@ def test_base_urls_drop_trailing_slashes() -> None:
     assert settings.bailian_rerank_base_url.endswith("/v1")
 
 
+def test_embedding_dimension_accepts_compose_string(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("EMBEDDING_DIMENSION", "1024")
+
+    settings = Settings(_env_file=None)
+
+    assert settings.embedding_dimension == 1024
+    assert isinstance(settings.embedding_dimension, int)
+
+
+@pytest.mark.parametrize("configured", ["1536", "1024.0", "01024", " 1024 "])
+def test_embedding_dimension_rejects_any_other_environment_value(
+    monkeypatch: pytest.MonkeyPatch,
+    configured: str,
+) -> None:
+    monkeypatch.setenv("EMBEDDING_DIMENSION", configured)
+
+    with pytest.raises(ValueError, match="EMBEDDING_DIMENSION must be exactly 1024"):
+        Settings(_env_file=None)
+
+
+@pytest.mark.parametrize("configured", [1024.0, True, None])
+def test_embedding_dimension_rejects_non_integer_programmatic_values(configured: object) -> None:
+    with pytest.raises(ValueError, match="EMBEDDING_DIMENSION must be exactly 1024"):
+        Settings.model_validate({"embedding_dimension": configured})
+
+
 def test_live_endpoints_must_share_one_beijing_workspace(tmp_path: Path) -> None:
     key_path = tmp_path / "key"
     key_path.write_text("test-key-value", encoding="utf-8")

backend/tests/unit/test_provider_smoke.py

@@ -1,5 +1,54 @@
+import pytest
+
+from app.core.config import Settings
 from app.ports.model_providers import ModelProviderError, ProviderErrorKind
-from app.tools.provider_smoke import failed_probe
+from app.tools import provider_smoke
+from app.tools.provider_smoke import ProbeResult, failed_probe
+
+
+def test_provider_smoke_settings_accept_compose_embedding_dimension(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setenv("EMBEDDING_DIMENSION", "1024")
+
+    settings = Settings(_env_file=None)
+
+    assert settings.embedding_dimension == 1024
+
+
+async def test_provider_smoke_entrypoint_accepts_compose_embedding_dimension(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    workspace_host = "workspace-test.cn-beijing.maas.aliyuncs.com"
+    monkeypatch.setenv("EMBEDDING_DIMENSION", "1024")
+    monkeypatch.setenv(
+        "BAILIAN_OPENAI_BASE_URL",
+        f"https://{workspace_host}/compatible-mode/v1",
+    )
+    monkeypatch.setenv(
+        "BAILIAN_RERANK_BASE_URL",
+        f"https://{workspace_host}/compatible-api/v1",
+    )
+    observed_dimensions: list[int] = []
+
+    def fake_api_key(settings: Settings) -> str:
+        observed_dimensions.append(settings.embedding_dimension)
+        return "test-only-api-key"
+
+    async def successful_probe(settings: Settings, api_key: str) -> ProbeResult:
+        observed_dimensions.append(settings.embedding_dimension)
+        assert api_key == "test-only-api-key"
+        return ProbeResult(capability="test", status="ok")
+
+    monkeypatch.setattr(Settings, "bailian_api_key", fake_api_key)
+    monkeypatch.setattr(provider_smoke, "probe_embedding", successful_probe)
+    monkeypatch.setattr(provider_smoke, "probe_rerank", successful_probe)
+    monkeypatch.setattr(provider_smoke, "probe_chat", successful_probe)
+
+    exit_code = await provider_smoke.async_main()
+
+    assert exit_code == 0
+    assert observed_dimensions == [1024, 1024, 1024, 1024]
 
 
 def test_failed_probe_only_exposes_sanitized_provider_fields() -> None: