fix: 100% OpenAI API verification for together and fireworks (#1946)

# What does this PR do?

TLDR: Changes needed to get 100% passing tests for OpenAI API
verification tests when run against Llama Stack with the `together`,
`fireworks`, and `openai` providers. And `groq` is better than before,
at 88% passing.

This cleans up the OpenAI API support for image message types
(specifically `image_url` types) and handling of the `response_format`
chat completion parameter. Both of these required a few more Pydantic
model definitions in our Inference API, just to move from the
not-quite-right stubs I had in place to something fleshed out to match
the actual OpenAI API specs.

As part of testing this, I also found and fixed a bug in the litellm
implementation of openai_completion and openai_chat_completion, so the
providers based on those should actually be working now.

The method `prepare_openai_completion_params` in
`llama_stack/providers/utils/inference/openai_compat.py` was improved to
actually recursively clean up input parameters, including handling of
lists, dicts, and dumping of Pydantic models to dicts. These changes
were required to get to 100% passing tests on the OpenAI API
verification against the `openai` provider.

With the above, the together.ai provider was passing as well as it is
without Llama Stack. But, since we have Llama Stack in the middle, I
took the opportunity to clean up the together.ai provider so that it now
also passes the OpenAI API spec tests we have at 100%. That means
together.ai is now passing our verification test better when using an
OpenAI client talking to Llama Stack than it is when hitting together.ai
directly, without Llama Stack in the middle.

And, another round of work for Fireworks to improve translation of
incoming OpenAI chat completion requests to Llama Stack chat completion
requests gets the fireworks provider passing at 100%. The server-side
fireworks.ai tool calling support with OpenAI chat completions and Llama
4 models isn't great yet, but by pointing the OpenAI clients at Llama
Stack's API we can clean things up and get everything working as
expected for Llama 4 models.

## Test Plan

### OpenAI API Verification Tests

I ran the OpenAI API verification tests as below and 100% of the tests
passed.

First, start a Llama Stack server that runs the `openai` provider with
the `gpt-4o` and `gpt-4o-mini` models deployed. There's not a template
setup to do this out of the box, so I added a
`tests/verifications/openai-api-verification-run.yaml` to do this.

First, ensure you have the necessary API key environment variables set:

```
export TOGETHER_API_KEY="..."
export FIREWORKS_API_KEY="..."
export OPENAI_API_KEY="..."
```

Then, run a Llama Stack server that serves up all these providers:

```
llama stack run \
      --image-type venv \
      tests/verifications/openai-api-verification-run.yaml
```

Finally, generate a new verification report against all these providers,
both with and without the Llama Stack server in the middle.

```
python tests/verifications/generate_report.py \
      --run-tests \
      --provider \
        together \
        fireworks \
        groq \
        openai \
        together-llama-stack \
        fireworks-llama-stack \
        groq-llama-stack \
        openai-llama-stack
```

You'll see that most of the configurations with Llama Stack in the
middle now pass at 100%, even though some of them do not pass at 100%
when hitting the backend provider's API directly with an OpenAI client.

### OpenAI Completion Integration Tests with vLLM:

I also ran the smaller `test_openai_completion.py` test suite (that's
not yet merged with the verification tests) on multiple of the
providers, since I had to adjust the method signature of
openai_chat_completion a bit and thus had to touch lots of these
providers to match. Here's the tests I ran there, all passing:

```
VLLM_URL="http://localhost:8000/v1" INFERENCE_MODEL="meta-llama/Llama-3.2-3B-Instruct" llama stack build --template remote-vllm --image-type venv --run
```

in another terminal

```
LLAMA_STACK_CONFIG=http://localhost:8321 INFERENCE_MODEL="meta-llama/Llama-3.2-3B-Instruct" python -m pytest -v tests/integration/inference/test_openai_completion.py --text-model "meta-llama/Llama-3.2-3B-Instruct"
```

### OpenAI Completion Integration Tests with ollama

```
INFERENCE_MODEL="llama3.2:3b-instruct-q8_0" llama stack build --template ollama --image-type venv --run
```

in another terminal

```
LLAMA_STACK_CONFIG=http://localhost:8321 INFERENCE_MODEL="llama3.2:3b-instruct-q8_0" python -m pytest -v tests/integration/inference/test_openai_completion.py --text-model "llama3.2:3b-instruct-q8_0"
```

### OpenAI Completion Integration Tests with together.ai

```
INFERENCE_MODEL="meta-llama/Llama-3.2-3B-Instruct-Turbo" llama stack build --template together --image-type venv --run
```

in another terminal

```
LLAMA_STACK_CONFIG=http://localhost:8321 INFERENCE_MODEL="meta-llama/Llama-3.2-3B-Instruct-Turbo" python -m pytest -v tests/integration/inference/test_openai_completion.py --text-model "meta-llama/Llama-3.2-3B-Instruct-Turbo"
```

### OpenAI Completion Integration Tests with fireworks.ai

```
INFERENCE_MODEL="meta-llama/Llama-3.1-8B-Instruct" llama stack build --template fireworks --image-type venv --run
```

in another terminal

```
LLAMA_STACK_CONFIG=http://localhost:8321 INFERENCE_MODEL="meta-llama/Llama-3.1-8B-Instruct" python -m pytest -v tests/integration/inference/test_openai_completion.py --text-model "meta-llama/Llama-3.1-8B-Instruct"

---------

Signed-off-by: Ben Browning <bbrownin@redhat.com>

tests/integration/inference/test_openai_completion.py

@@ -115,7 +115,7 @@ def test_openai_completion_streaming(openai_client, client_with_models, text_mod
         stream=True,
         max_tokens=50,
     )
-    streamed_content = [chunk.choices[0].text for chunk in response]
+    streamed_content = [chunk.choices[0].text or "" for chunk in response]
     content_str = "".join(streamed_content).lower().strip()
     assert len(content_str) > 10
 

tests/verifications/conf/fireworks-llama-stack.yaml

@@ -0,0 +1,14 @@
+base_url: http://localhost:8321/v1/openai/v1
+api_key_var: FIREWORKS_API_KEY
+models:
+- fireworks/llama-v3p3-70b-instruct
+- fireworks/llama4-scout-instruct-basic
+- fireworks/llama4-maverick-instruct-basic
+model_display_names:
+  fireworks/llama-v3p3-70b-instruct: Llama-3.3-70B-Instruct
+  fireworks/llama4-scout-instruct-basic: Llama-4-Scout-Instruct
+  fireworks/llama4-maverick-instruct-basic: Llama-4-Maverick-Instruct
+test_exclusions:
+  fireworks/llama-v3p3-70b-instruct:
+  - test_chat_non_streaming_image
+  - test_chat_streaming_image

tests/verifications/conf/groq-llama-stack.yaml

@@ -0,0 +1,14 @@
+base_url: http://localhost:8321/v1/openai/v1
+api_key_var: GROQ_API_KEY
+models:
+- groq/llama-3.3-70b-versatile
+- groq/llama-4-scout-17b-16e-instruct
+- groq/llama-4-maverick-17b-128e-instruct
+model_display_names:
+  groq/llama-3.3-70b-versatile: Llama-3.3-70B-Instruct
+  groq/llama-4-scout-17b-16e-instruct: Llama-4-Scout-Instruct
+  groq/llama-4-maverick-17b-128e-instruct: Llama-4-Maverick-Instruct
+test_exclusions:
+  groq/llama-3.3-70b-versatile:
+  - test_chat_non_streaming_image
+  - test_chat_streaming_image

tests/verifications/conf/groq.yaml

@@ -2,12 +2,12 @@ base_url: https://api.groq.com/openai/v1
 api_key_var: GROQ_API_KEY
 models:
 - llama-3.3-70b-versatile
-- llama-4-scout-17b-16e-instruct
-- llama-4-maverick-17b-128e-instruct
+- meta-llama/llama-4-scout-17b-16e-instruct
+- meta-llama/llama-4-maverick-17b-128e-instruct
 model_display_names:
   llama-3.3-70b-versatile: Llama-3.3-70B-Instruct
-  llama-4-scout-17b-16e-instruct: Llama-4-Scout-Instruct
-  llama-4-maverick-17b-128e-instruct: Llama-4-Maverick-Instruct
+  meta-llama/llama-4-scout-17b-16e-instruct: Llama-4-Scout-Instruct
+  meta-llama/llama-4-maverick-17b-128e-instruct: Llama-4-Maverick-Instruct
 test_exclusions:
   llama-3.3-70b-versatile:
   - test_chat_non_streaming_image

tests/verifications/conf/openai-llama-stack.yaml

@@ -0,0 +1,9 @@
+base_url: http://localhost:8321/v1/openai/v1
+api_key_var: OPENAI_API_KEY
+models:
+- openai/gpt-4o
+- openai/gpt-4o-mini
+model_display_names:
+  openai/gpt-4o: gpt-4o
+  openai/gpt-4o-mini: gpt-4o-mini
+test_exclusions: {}

tests/verifications/conf/together-llama-stack.yaml

@@ -0,0 +1,14 @@
+base_url: http://localhost:8321/v1/openai/v1
+api_key_var: TOGETHER_API_KEY
+models:
+- together/meta-llama/Llama-3.3-70B-Instruct-Turbo
+- together/meta-llama/Llama-4-Scout-17B-16E-Instruct
+- together/meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8
+model_display_names:
+  together/meta-llama/Llama-3.3-70B-Instruct-Turbo: Llama-3.3-70B-Instruct
+  together/meta-llama/Llama-4-Scout-17B-16E-Instruct: Llama-4-Scout-Instruct
+  together/meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8: Llama-4-Maverick-Instruct
+test_exclusions:
+  together/meta-llama/Llama-3.3-70B-Instruct-Turbo:
+  - test_chat_non_streaming_image
+  - test_chat_streaming_image

tests/verifications/generate_report.py

@@ -67,7 +67,17 @@ RESULTS_DIR.mkdir(exist_ok=True)
 # Maximum number of test result files to keep per provider
 MAX_RESULTS_PER_PROVIDER = 1
 
-PROVIDER_ORDER = ["together", "fireworks", "groq", "cerebras", "openai"]
+PROVIDER_ORDER = [
+    "together",
+    "fireworks",
+    "groq",
+    "cerebras",
+    "openai",
+    "together-llama-stack",
+    "fireworks-llama-stack",
+    "groq-llama-stack",
+    "openai-llama-stack",
+]
 
 VERIFICATION_CONFIG = _load_all_verification_configs()
 

tests/verifications/openai-api-verification-run.yaml

@@ -0,0 +1,146 @@
+version: '2'
+image_name: openai-api-verification
+apis:
+- inference
+- telemetry
+- tool_runtime
+- vector_io
+providers:
+  inference:
+  - provider_id: together
+    provider_type: remote::together
+    config:
+      url: https://api.together.xyz/v1
+      api_key: ${env.TOGETHER_API_KEY:}
+  - provider_id: fireworks
+    provider_type: remote::fireworks
+    config:
+      url: https://api.fireworks.ai/inference/v1
+      api_key: ${env.FIREWORKS_API_KEY}
+  - provider_id: groq
+    provider_type: remote::groq
+    config:
+      url: https://api.groq.com
+      api_key: ${env.GROQ_API_KEY}
+  - provider_id: openai
+    provider_type: remote::openai
+    config:
+      url: https://api.openai.com/v1
+      api_key: ${env.OPENAI_API_KEY:}
+  - provider_id: sentence-transformers
+    provider_type: inline::sentence-transformers
+    config: {}
+  vector_io:
+  - provider_id: faiss
+    provider_type: inline::faiss
+    config:
+      kvstore:
+        type: sqlite
+        namespace: null
+        db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/openai}/faiss_store.db
+  telemetry:
+  - provider_id: meta-reference
+    provider_type: inline::meta-reference
+    config:
+      service_name: "${env.OTEL_SERVICE_NAME:\u200B}"
+      sinks: ${env.TELEMETRY_SINKS:console,sqlite}
+      sqlite_db_path: ${env.SQLITE_DB_PATH:~/.llama/distributions/openai/trace_store.db}
+  tool_runtime:
+  - provider_id: brave-search
+    provider_type: remote::brave-search
+    config:
+      api_key: ${env.BRAVE_SEARCH_API_KEY:}
+      max_results: 3
+  - provider_id: tavily-search
+    provider_type: remote::tavily-search
+    config:
+      api_key: ${env.TAVILY_SEARCH_API_KEY:}
+      max_results: 3
+  - provider_id: code-interpreter
+    provider_type: inline::code-interpreter
+    config: {}
+  - provider_id: rag-runtime
+    provider_type: inline::rag-runtime
+    config: {}
+  - provider_id: model-context-protocol
+    provider_type: remote::model-context-protocol
+    config: {}
+  - provider_id: wolfram-alpha
+    provider_type: remote::wolfram-alpha
+    config:
+      api_key: ${env.WOLFRAM_ALPHA_API_KEY:}
+metadata_store:
+  type: sqlite
+  db_path: ${env.SQLITE_STORE_DIR:~/.llama/distributions/openai}/registry.db
+models:
+- metadata: {}
+  model_id: together/meta-llama/Llama-3.3-70B-Instruct-Turbo
+  provider_id: together
+  provider_model_id: meta-llama/Llama-3.3-70B-Instruct-Turbo
+  model_type: llm
+- metadata: {}
+  model_id: together/meta-llama/Llama-4-Scout-17B-16E-Instruct
+  provider_id: together
+  provider_model_id: meta-llama/Llama-4-Scout-17B-16E-Instruct
+  model_type: llm
+- metadata: {}
+  model_id: together/meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8
+  provider_id: together
+  provider_model_id: meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8
+  model_type: llm
+- metadata: {}
+  model_id: fireworks/llama-v3p3-70b-instruct
+  provider_id: fireworks
+  provider_model_id: accounts/fireworks/models/llama-v3p3-70b-instruct
+  model_type: llm
+- metadata: {}
+  model_id: fireworks/llama4-scout-instruct-basic
+  provider_id: fireworks
+  provider_model_id: accounts/fireworks/models/llama4-scout-instruct-basic
+  model_type: llm
+- metadata: {}
+  model_id: fireworks/llama4-maverick-instruct-basic
+  provider_id: fireworks
+  provider_model_id: accounts/fireworks/models/llama4-maverick-instruct-basic
+  model_type: llm
+- metadata: {}
+  model_id: groq/llama-3.3-70b-versatile
+  provider_id: groq
+  provider_model_id: groq/llama-3.3-70b-versatile
+  model_type: llm
+- metadata: {}
+  model_id: groq/llama-4-scout-17b-16e-instruct
+  provider_id: groq
+  provider_model_id: groq/meta-llama/llama-4-scout-17b-16e-instruct
+  model_type: llm
+- metadata: {}
+  model_id: groq/llama-4-maverick-17b-128e-instruct
+  provider_id: groq
+  provider_model_id: groq/meta-llama/llama-4-maverick-17b-128e-instruct
+  model_type: llm
+- metadata: {}
+  model_id: openai/gpt-4o
+  provider_id: openai
+  provider_model_id: openai/gpt-4o
+  model_type: llm
+- metadata: {}
+  model_id: openai/gpt-4o-mini
+  provider_id: openai
+  provider_model_id: openai/gpt-4o-mini
+  model_type: llm
+shields: []
+vector_dbs: []
+datasets: []
+scoring_fns: []
+benchmarks: []
+tool_groups:
+- toolgroup_id: builtin::websearch
+  provider_id: tavily-search
+- toolgroup_id: builtin::rag
+  provider_id: rag-runtime
+- toolgroup_id: builtin::code_interpreter
+  provider_id: code-interpreter
+- toolgroup_id: builtin::wolfram_alpha
+  provider_id: wolfram-alpha
+server:
+  port: 8321

tests/verifications/openai_api/fixtures/fixtures.py

@@ -99,6 +99,9 @@ def model_mapping(provider, providers_model_mapping):
 
 @pytest.fixture
 def openai_client(base_url, api_key):
+    # Simplify running against a local Llama Stack
+    if "localhost" in base_url and not api_key:
+        api_key = "empty"
     return OpenAI(
         base_url=base_url,
         api_key=api_key,