DeepSeek V4 Flash (New) route hangs - no response from zen gateway

[sergiomaciel]

Description

The deepseek-v4-flash model (marketed as "DeepSeek V4 Flash (New)") on the opencode zen gateway fails to respond.

Endpoint

POST https://opencode.ai/zen/go/v1/chat/completions
Authorization: Bearer $OPENCODE_API_KEY

Symptoms

• Without streaming: 0 bytes received, times out after 90s
• With streaming: Only SSE : keep-alive pings, no actual content arrives
• With/without max_tokens: same result
• Billing: user is paying and has balance available

Reproduction

curl -sS -m 60 "https://opencode.ai/zen/go/v1/chat/completions" \
  -H "Authorization: Bearer $OPENCODE_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"model":"deepseek-v4-flash","messages":[{"role":"user","content":"hello"}]}'
# Result: timeout, 0 bytes

Comparison

Other models via the same endpoint/key work fine:

• qwen3.8-max → 2s
• glm-5.2 → 1.6s
• deepseek-v4-pro → 13s

Environment

• opencode v1.18.13
• Linux (Ubuntu 20.04)
• git v2.50.1

Expected

deepseek-v4-flash should respond like other models.

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• deepseek-v4-flash on opencode-go drops connection before response (pro works on same endpoint) #40465: Same symptom — deepseek-v4-flash on opencode.ai/zen/go/v1 drops connection before any HTTP response while deepseek-v4-pro on the same endpoint/key works fine; includes curl reproduction.
• DeepSeek V4 Flash stop working #40464: DeepSeek V4 Flash stopped working (both free and paid tiers), deepseek-v4-pro still works — same provider, same version (v1.18.13).
• Deepseek V4 Flash Free not working #40467: Deepseek V4 Flash Free not working — another report of the same hang/no-response pattern.

If your issue is the same underlying server-side routing problem with the flash lane on the zen/go backend, please add a reaction or comment to one of those existing issues rather than opening a new one.