Proxy API `forge.tensorblock.co` rejects valid OpenAI-compatible payload

[dcloud347]

Description

I'm using a proxy (https://api.forge.tensorblock.co/v1/chat/completions) that is supposed to be OpenAI-compatible. When I send the exact same payload to OpenAI's API, it works perfectly. However, when I send the same payload to the Forge proxy, I get a validation error:

curl https://api.openai.com/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer sk-..." \
  -d @openai_payload.json
# ✅ Response: success

curl https://api.forge.tensorblock.co/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer forge-..." \
  -d @forge_payload.json
# ❌ Response:
{
  "detail": [
    {
      "type": "list_type",
      "loc": ["body", "messages", 2, "content", "list[OpenAIContentModel]"],
      "msg": "Input should be a valid list",
      "input": null
    },
    {
      "type": "string_type",
      "loc": ["body", "messages", 2, "content", "str"],
      "msg": "Input should be a valid string",
      "input": null
    }
  ]
}

Payload

I'm attaching the exact payload as payload.json used in both cases.

Expected Behavior

Since the Forge proxy is advertised as OpenAI-compatible, it should accept and correctly handle payloads that OpenAI accepts — including tool_calls and content: null cases as returned when finish_reason = "tool_calls".

Actual Behavior

The proxy fails with a validation error, specifically rejecting content: null.

Suggested Fix

The proxy implementation should:

• Accept content: null when tool_calls are present, which is valid OpenAI behavior.
• Update Pydantic schema (if used) to allow Union[str, None] instead of just str.
• Make sure messages[].content can be null per OpenAI's official spec.

forge_payload.json

openai_payload.json

[wilsonccccc]

#26

[dcloud347]

Reproduce payload forge_payload.json

Error Response:
{"detail":[{"type":"list_type","loc":["body","messages",1,"content","list[OpenAIContentModel]"],"msg":"Input should be a valid list","input":null},{"type":"string_type","loc":["body","messages",1,"content","str"],"msg":"Input should be a valid string","input":null}]}

[wilsonccccc]

#27

curl http://0.0.0.0:8000/v1/chat/completions \             
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer forge-7fb45c0dd1c21ddebc8681c95bccb3c301b4" \
  -d "@/Users/wenjingyu/Desktop/forge_payload.json"
{"id":"chatcmpl-BwMHwQc2Iwe66cakJHG8pzVhuErrA","object":"chat.completion","created":1753248400,"model":"gpt-4o-2024-08-06","choices":[{"index":0,"message":{"role":"assistant","content":"I found the file `fireball.py` located at `pychemia/code/fireball/fireball.py` in the Neo4j knowledge graph. The node ID for this file is 11119. If you need more information about this file or its contents, please let me know!","refusal":null,"annotations":[]},"logprobs":null,"finish_reason":"stop"}],"usage":{"prompt_tokens":235,"completion_tokens":59,"total_tokens":294,"prompt_tokens_details":{"cached_tokens":0,"audio_tokens":0},"completion_tokens_details":{"reasoning_tokens":0,"audio_tokens":0,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"service_tier":"default","system_fingerprint":"fp_a288987b44"}%