Skip OpenAI messages-dispatch gpt-5.x defaults for OpenCode groups and
composite OpenCode targets. Filter unpriced claude-* billing candidates,
estimate count_tokens locally, sanitize body session IDs before setting
X-OpenCode-Session, and treat Zen 402 as recoverable payg cooldown.
Stop rewriting the inbound body before protocol routing so account
model_mapping applies once and usage_logs.model stays the client name.
Keep the internal platform ID opencode_go. Product surface is OpenCode
with account_mode zen|go, model-aware routing across Chat Completions,
Responses, and Anthropic Messages, and X-OpenCode-Session derived from
prompt_cache_key / metadata.user_id so prompt cache can hit.
Unmatched models fall back to /v1/chat/completions. Related to #6742.
Zhaofeng Li