refactor: replace blackforest package with custom async BFL client

Implement bulkgen/providers/bfl.py with a fully async httpx-based client
that supports all current and future BFL models (including flux-2-*).
Remove the blackforest dependency and simplify the image provider by
eliminating the asyncio.to_thread wrapper.

bulkgen/providers/bfl.py

@@ -0,0 +1,148 @@
+"""Async client for the BlackForestLabs image generation API."""
+
+from __future__ import annotations
+
+import asyncio
+from dataclasses import dataclass
+from typing import cast
+
+import httpx
+
+_BASE_URL = "https://api.bfl.ai"
+_DEFAULT_POLL_INTERVAL = 1.0
+_DEFAULT_TIMEOUT = 300.0
+
+
+@dataclass
+class BFLResult:
+    """Successful generation result from the BFL API."""
+
+    task_id: str
+    sample_url: str
+
+
+class BFLError(Exception):
+    """Error returned by the BFL API."""
+
+
+class BFLClient:
+    """Async client for the BlackForestLabs image generation API.
+
+    Submits generation requests and polls for results.
+    """
+
+    _api_key: str
+    _base_url: str
+    _poll_interval: float
+    _timeout: float
+
+    def __init__(
+        self,
+        api_key: str,
+        *,
+        base_url: str = _BASE_URL,
+        poll_interval: float = _DEFAULT_POLL_INTERVAL,
+        timeout: float = _DEFAULT_TIMEOUT,
+    ) -> None:
+        self._api_key = api_key
+        self._base_url = base_url
+        self._poll_interval = poll_interval
+        self._timeout = timeout
+
+    async def generate(self, model: str, inputs: dict[str, object]) -> BFLResult:
+        """Submit a generation request and poll until the result is ready.
+
+        Args:
+            model: BFL model name (e.g. ``flux-pro-1.1``, ``flux-2-pro``).
+            inputs: Model-specific parameters (prompt, dimensions, etc.).
+
+        Returns:
+            A :class:`BFLResult` containing the task ID and sample image URL.
+
+        Raises:
+            BFLError: If the API returns an error or the request times out.
+        """
+        headers = {
+            "x-key": self._api_key,
+            "Content-Type": "application/json",
+            "Accept": "application/json",
+        }
+
+        async with httpx.AsyncClient(
+            base_url=self._base_url, headers=headers
+        ) as client:
+            task_id, polling_url = await self._submit(client, model, inputs)
+            sample_url = await self._poll(client, task_id, polling_url)
+
+        return BFLResult(task_id=task_id, sample_url=sample_url)
+
+    async def _submit(
+        self,
+        client: httpx.AsyncClient,
+        model: str,
+        inputs: dict[str, object],
+    ) -> tuple[str, str]:
+        """POST the generation request and return (task_id, polling_url)."""
+        response = await client.post(f"/v1/{model}", json=inputs)
+
+        if response.status_code == 422:  # noqa: PLR2004
+            body = cast(dict[str, object], response.json())
+            detail = body.get("detail", body)
+            msg = f"BFL validation error for model '{model}': {detail}"
+            raise BFLError(msg)
+
+        if response.status_code != 200:  # noqa: PLR2004
+            msg = f"BFL API returned status {response.status_code}: {response.text}"
+            raise BFLError(msg)
+
+        body = cast(dict[str, object], response.json())
+        task_id = body.get("id")
+        polling_url = body.get("polling_url")
+
+        if not isinstance(task_id, str) or not isinstance(polling_url, str):
+            msg = f"BFL API response missing 'id' or 'polling_url': {body}"
+            raise BFLError(msg)
+
+        return task_id, polling_url
+
+    async def _poll(
+        self,
+        client: httpx.AsyncClient,
+        task_id: str,
+        polling_url: str,
+    ) -> str:
+        """Poll the task until ready and return the sample image URL."""
+        elapsed = 0.0
+
+        while elapsed < self._timeout:
+            response = await client.get(polling_url)
+
+            if response.status_code != 200:  # noqa: PLR2004
+                msg = f"BFL polling returned status {response.status_code}: {response.text}"
+                raise BFLError(msg)
+
+            body = cast(dict[str, object], response.json())
+            status = body.get("status")
+
+            if status == "Ready":
+                result = body.get("result")
+                if not isinstance(result, dict):
+                    msg = f"BFL task {task_id} ready but no result dict: {body}"
+                    raise BFLError(msg)
+                result_dict = cast(dict[str, object], result)
+                sample = result_dict.get("sample")
+                if not isinstance(sample, str):
+                    msg = f"BFL task {task_id} ready but no sample URL: {result}"
+                    raise BFLError(msg)
+                return sample
+
+            if status in ("Error", "Failed"):
+                error_msg = body.get("result", body)
+                msg = f"BFL task {task_id} failed: {error_msg}"
+                raise BFLError(msg)
+
+            await asyncio.sleep(self._poll_interval)
+            elapsed += self._poll_interval
+
+        msg = f"BFL task {task_id} timed out after {self._timeout}s"
+        raise BFLError(msg)

bulkgen/providers/image.py

@@ -2,24 +2,15 @@
 
 from __future__ import annotations
 
-import asyncio
 import base64
 from pathlib import Path
 from typing import override
 
 import httpx
-from blackforest import BFLClient  # pyright: ignore[reportMissingTypeStubs]
-from blackforest.types.general.client_config import (  # pyright: ignore[reportMissingTypeStubs]
-    ClientConfig,
-)
-from blackforest.types.responses.responses import (  # pyright: ignore[reportMissingTypeStubs]
-    SyncResponse,
-)
 
 from bulkgen.config import TargetConfig
 from bulkgen.providers import Provider
-
+from bulkgen.providers.bfl import BFLClient
-_BFL_SYNC_CONFIG = ClientConfig(sync=True, timeout=300)
 
 
 def _encode_image_b64(path: Path) -> str:
@@ -61,24 +52,10 @@ class ImageProvider(Provider):
             ctrl_path = project_dir / control_name
             inputs["control_image"] = _encode_image_b64(ctrl_path)
 
-        result = await asyncio.to_thread(
+        result = await self._client.generate(resolved_model, inputs)
-            self._client.generate, resolved_model, inputs, _BFL_SYNC_CONFIG
-        )
-
-        if not isinstance(result, SyncResponse):
-            msg = (
-                f"BFL API returned unexpected response type for target '{target_name}'"
-            )
-            raise RuntimeError(msg)
-
-        result_dict: dict[str, str] = result.result  # pyright: ignore[reportUnknownMemberType, reportUnknownVariableType]
-        image_url = result_dict.get("sample")
-        if not image_url:
-            msg = f"BFL API did not return an image URL for target '{target_name}'"
-            raise RuntimeError(msg)
 
         async with httpx.AsyncClient() as http:
-            response = await http.get(image_url)
+            response = await http.get(result.sample_url)
             _ = response.raise_for_status()
 
         _ = output_path.write_bytes(response.content)

pyproject.toml

@@ -5,7 +5,7 @@ description = "Bulk-Generate Images with Generative AI"
 readme = "README.md"
 requires-python = ">=3.13"
 dependencies = [
-    "blackforest>=0.1.3",
+    "httpx>=0.27.0",
     "mistralai>=1.0.0",
     "networkx>=3.6.1",
     "pydantic>=2.12.5",

tests/test_providers.py

@@ -13,6 +13,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 import pytest
 
 from bulkgen.config import TargetConfig
+from bulkgen.providers.bfl import BFLResult
 from bulkgen.providers.image import ImageProvider
 from bulkgen.providers.image import (
     _encode_image_b64 as encode_image_b64,  # pyright: ignore[reportPrivateUsage]
@@ -22,10 +23,11 @@ from bulkgen.providers.text import TextProvider
 
 def _make_bfl_mocks(
     image_bytes: bytes,
-) -> tuple[MagicMock, MagicMock]:
+) -> tuple[BFLResult, MagicMock]:
-    """Return (mock_result, mock_http) for BFL image generation tests."""
+    """Return (bfl_result, mock_http) for BFL image generation tests."""
-    mock_result = MagicMock()
+    bfl_result = BFLResult(
-    mock_result.result = {"sample": "https://example.com/img.png"}
+        task_id="test-task-id", sample_url="https://example.com/img.png"
+    )
 
     mock_response = MagicMock()
     mock_response.content = image_bytes
@@ -36,7 +38,7 @@ def _make_bfl_mocks(
     mock_http.__aenter__ = AsyncMock(return_value=mock_http)
     mock_http.__aexit__ = AsyncMock(return_value=False)
 
-    return mock_result, mock_http
+    return bfl_result, mock_http
 
 
 def _make_mistral_mock(response: MagicMock) -> AsyncMock:
@@ -68,14 +70,13 @@ class TestImageProvider:
         self, project_dir: Path, image_bytes: bytes
     ) -> None:
         target_config = TargetConfig(prompt="A red square")
-        mock_result, mock_http = _make_bfl_mocks(image_bytes)
+        bfl_result, mock_http = _make_bfl_mocks(image_bytes)
 
         with (
             patch("bulkgen.providers.image.BFLClient") as mock_cls,
-            patch("bulkgen.providers.image.isinstance", return_value=True),
             patch("bulkgen.providers.image.httpx.AsyncClient") as mock_http_cls,
         ):
-            mock_cls.return_value.generate.return_value = mock_result
+            mock_cls.return_value.generate = AsyncMock(return_value=bfl_result)
             mock_http_cls.return_value = mock_http
 
             provider = ImageProvider(api_key="test-key")
@@ -95,15 +96,14 @@ class TestImageProvider:
         self, project_dir: Path, image_bytes: bytes
     ) -> None:
         target_config = TargetConfig(prompt="A banner", width=1920, height=480)
-        mock_result, mock_http = _make_bfl_mocks(image_bytes)
+        bfl_result, mock_http = _make_bfl_mocks(image_bytes)
 
         with (
             patch("bulkgen.providers.image.BFLClient") as mock_cls,
-            patch("bulkgen.providers.image.isinstance", return_value=True),
             patch("bulkgen.providers.image.httpx.AsyncClient") as mock_http_cls,
         ):
-            client_instance = mock_cls.return_value
+            mock_generate = AsyncMock(return_value=bfl_result)
-            client_instance.generate.return_value = mock_result
+            mock_cls.return_value.generate = mock_generate
             mock_http_cls.return_value = mock_http
 
             provider = ImageProvider(api_key="test-key")
@@ -115,7 +115,7 @@ class TestImageProvider:
                 project_dir=project_dir,
             )
 
-            call_args = client_instance.generate.call_args
+            call_args = mock_generate.call_args
             inputs = call_args[0][1]
             assert inputs["width"] == 1920
             assert inputs["height"] == 480
@@ -127,15 +127,14 @@ class TestImageProvider:
         _ = ref_path.write_bytes(b"reference image data")
 
         target_config = TargetConfig(prompt="Like this", reference_image="ref.png")
-        mock_result, mock_http = _make_bfl_mocks(image_bytes)
+        bfl_result, mock_http = _make_bfl_mocks(image_bytes)
 
         with (
             patch("bulkgen.providers.image.BFLClient") as mock_cls,
-            patch("bulkgen.providers.image.isinstance", return_value=True),
             patch("bulkgen.providers.image.httpx.AsyncClient") as mock_http_cls,
         ):
-            client_instance = mock_cls.return_value
+            mock_generate = AsyncMock(return_value=bfl_result)
-            client_instance.generate.return_value = mock_result
+            mock_cls.return_value.generate = mock_generate
             mock_http_cls.return_value = mock_http
 
             provider = ImageProvider(api_key="test-key")
@@ -147,29 +146,28 @@ class TestImageProvider:
                 project_dir=project_dir,
             )
 
-            call_args = client_instance.generate.call_args
+            call_args = mock_generate.call_args
             inputs = call_args[0][1]
             assert "image_prompt" in inputs
             assert inputs["image_prompt"] == encode_image_b64(ref_path)
 
     async def test_image_no_sample_url_raises(self, project_dir: Path) -> None:
         target_config = TargetConfig(prompt="x")
-        mock_result = MagicMock()
-        mock_result.result = {}
 
-        with (
+        with patch("bulkgen.providers.image.BFLClient") as mock_cls:
-            patch("bulkgen.providers.image.BFLClient") as mock_cls,
+            from bulkgen.providers.bfl import BFLError
-            patch("bulkgen.providers.image.isinstance", return_value=True),
+
-        ):
+            mock_cls.return_value.generate = AsyncMock(
-            mock_cls.return_value.generate.return_value = mock_result
+                side_effect=BFLError("BFL task test ready but no sample URL: {}")
+            )
 
             provider = ImageProvider(api_key="test-key")
-            with pytest.raises(RuntimeError, match="did not return an image URL"):
+            with pytest.raises(BFLError, match="no sample URL"):
                 await provider.generate(
                     target_name="fail.png",
                     target_config=target_config,
                     resolved_prompt="x",
-                    resolved_model="flux-pro",
+                    resolved_model="flux-pro-1.1",
                     project_dir=project_dir,
                 )
 

uv.lock

@@ -44,26 +44,12 @@ wheels = [
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 ]
 
-[[package]]
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-version = "0.1.3"
-source = { registry = "https://pypi.org/simple" }
-dependencies = [
-    { name = "pillow" },
-    { name = "pydantic" },
-    { name = "requests" },
-]
-sdist = { url = "https://files.pythonhosted.org/packages/b4/e5/e580c9ae37bcf2d70365c452d3e6a34e5f9cf0ced4fcb63430d46530a908/blackforest-0.1.3.tar.gz", hash = "sha256:8e5b069690a036fda90c1f3b8b44189a873522d54852cbea5642f2bcf4df3158", size = 18834, upload-time = "2025-09-10T10:02:12.79Z" }
-wheels = [
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-]
-
 [[package]]
 name = "bulkgen"
 version = "0.1.0"
 source = { editable = "." }
 dependencies = [
-    { name = "blackforest" },
+    { name = "httpx" },
     { name = "mistralai" },
     { name = "networkx" },
     { name = "pydantic" },
@@ -81,7 +67,7 @@ dev = [
 
 [package.metadata]
 requires-dist = [
-    { name = "blackforest", specifier = ">=0.1.3" },
+    { name = "httpx", specifier = ">=0.27.0" },
     { name = "mistralai", specifier = ">=1.0.0" },
     { name = "networkx", specifier = ">=3.6.1" },
     { name = "pydantic", specifier = ">=2.12.5" },
@@ -423,25 +409,6 @@ wheels = [
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 ]
 
-[[package]]
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-version = "10.4.0"
-source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/cd/74/ad3d526f3bf7b6d3f408b73fde271ec69dfac8b81341a318ce825f2b3812/pillow-10.4.0.tar.gz", hash = "sha256:166c1cd4d24309b30d61f79f4a9114b7b2313d7450912277855ff5dfd7cd4a06", size = 46555059, upload-time = "2024-07-01T09:48:43.583Z" }
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 [[package]]
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 version = "1.6.0"