Files
ModelRouter/internal/lua/adapters/opencodezen.lua
JianFeeeee 791d198f47 fix(opencode): make x-opencode-session stable so the upstream prefix cache can hit
The opencode adapters derived x-opencode-session from meta.timestamp, i.e. a
brand new session on every request. The upstream prefix cache is
session-scoped, so no request could ever hit it, and the cache fields the
endpoint does report (prompt_tokens_details.cached_tokens,
prompt_cache_hit_tokens/prompt_cache_miss_tokens) always came back 0/absent.

Measured against the live endpoint, same 6032-token prompt:

  fixed session id   -> 2nd call: hit 5888, miss 144
  rotating session id -> every call: hit 0, miss 6032

Fix: derive the session from the source name (stable), matching how
x-opencode-project is already derived. x-opencode-request stays unique per
request — it is only a request identifier, not part of the cache key.
Applied to both opencodego and opencodezen.

Through the gateway the same prompt now reports, on the 2nd call:
  details={'cached_tokens': 5888} hit=5888 miss=144      (non-streaming)
  prompt_tokens_details={'cached_tokens': 5888}          (streaming)

Test: TestOpenCodeSessionIsStableForCache asserts the session is stable
across requests for one source while the request id differs.
2026-09-11 15:42:22 +08:00

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local adapter = {}
adapter.name = "opencodezen"
adapter.version = "1.0.0"
adapter.endpoint = "/chat/completions"
-- OpenCode Zen按量付费端点https://opencode.ai/zen/v1
--
-- 与 OpenCode Goopencodego.luahttps://opencode.ai/zen/go/v1是两个不同的
-- 服务,行为要求并不相同,因此各有专用适配器:
--
-- * 本适配器Zen服务免费池 / 按量付费池。免费模型必须带 opencode 客户端
-- 指纹UA + x-opencode-*),否则上游拒绝:"free tier can only be used in
-- OpenCode"。Zen 的免费池以非 thinking 模型为主,历史上回传
-- reasoning_content 会引出上游报错故这里剥掉Go 侧相反,见 opencodego.lua
-- * Go 订阅读者请看 opencodego.lua那边**必须**回传 reasoning_content
-- 否则 thinking 模式直接 400。
--
-- 缺 x-opencode-client/session/request/project 身份头会被判为匿名客户端,
-- 部分模型在带 tools 时上游直接失败(流式返回单 chunk
-- "finish_reason":"network_error" 空 content非流式 503
-- "Endpoint is unavailable",表现为"空回复")。
adapter.headers = {
["User-Agent"] = "opencode/1.18.21 ai-sdk/provider-utils/4.0.23 runtime/bun/1.3.14",
}
-- 每请求生成身份头。沙箱无 os/math用 meta.timestamp + 请求体哈希派生:
-- 同秒内重复请求 id 相同可接受zen 只校验存在性,不校验格式)。
local function rand_id(prefix, seed)
return prefix .. string.sub(sha256_hex(seed), 1, 24)
end
function adapter.build_headers(meta)
local ts = tostring(meta.timestamp or "")
local src = (meta.source and meta.source.name) or ""
return {
["User-Agent"] = adapter.headers["User-Agent"],
["x-opencode-client"] = "cli",
-- project 固定:同网关实例共享一个工作区身份
["x-opencode-project"] = string.sub(sha256_hex("llmsproxy|" .. src), 1, 32),
-- session 必须**按源稳定**,不能每请求换:上游的前缀缓存在同一 session
-- 内才复用。实测(同一段 6032 token 提示词):
-- 固定 session -> 第 2 次命中 5888/6032cached_tokens=5888
-- 每请求换 session -> 永远 0 命中
-- 原先用 meta.timestamp 派生,等于每请求都是新会话,缓存永远无效,
-- 上游也无法做会话亲和路由。
["x-opencode-session"] = rand_id("ses_", "session|llmsproxy|" .. src),
-- request id 仍每请求唯一(它只是请求标识,不参与缓存键)
["x-opencode-request"] = rand_id("msg_", "request|" .. ts .. "|" .. tostring(meta.body or "")),
}
end
-- OpenAI /chat/completions format (pass-through, strip provider-specific fields)
-- zen 上游 schema 只接受 text content part无视觉/音频能力):多模态 part
-- image_url / input_audio / file 等)一律剥离。剥离后 content 变空的消息
-- 若不再携带 tool_calls / tool_call_id 才整条丢弃(避免上游
-- "unknown variant `image_url`, expected `text`");带工具调用的必须保留,
-- 否则会把紧随其后的 tool 结果变成孤儿,模型会反复重发同一个调用。
-- zen 上游角色白名单只有 system / user / assistant / tool / latest_reminder
-- OpenAI 的 developer及 function 等)不在其中,直接透传会触发上游
-- "unknown variant `developer`, expected one of ..." 错误;统一归一化为 system。
local ROLE_WHITELIST = {
system = true,
user = true,
assistant = true,
tool = true,
latest_reminder = true,
}
function adapter.transform_request(raw_body)
local ok, req = pcall(json.decode, raw_body)
if not ok then return raw_body end
req.disable_thinking = nil
req.extra_body = nil
-- stream_options is only valid alongside stream:true; sending it on a
-- non-streaming request is rejected by strict upstreams.
if req.stream then
if type(req.stream_options) ~= "table" then req.stream_options = {} end
req.stream_options.include_usage = true
end
if req.messages then
local kept = {}
for _, msg in ipairs(req.messages) do
if type(msg.role) == "string" and not ROLE_WHITELIST[msg.role] then
msg.role = "system"
end
-- Zen 免费池不接受回传 reasoning_contentGo 侧相反)
msg.reasoning_content = nil
local drop = false
if type(msg.content) == "table" then
local parts = {}
for _, part in ipairs(msg.content) do
if type(part) == "table" and part.type ~= nil and part.type ~= "text" then
-- multimodal part not supported by zen
else
table.insert(parts, part)
end
end
if #parts == 0 then
-- Content collapsed to nothing after stripping unsupported
-- parts. A message that still carries a tool call must
-- NEVER be dropped: the very next message is its tool
-- result, and dropping the call orphans that result. The
-- model then sees a result for a call it never made and
-- re-issues the same tool call on every turn (observed as
-- an infinite "repeated tool call" loop).
if (type(msg.tool_calls) == "table" and #msg.tool_calls > 0)
or msg.tool_call_id ~= nil then
msg.content = ""
else
drop = true
end
else
msg.content = parts
end
end
if not drop then
table.insert(kept, msg)
end
end
req.messages = kept
end
return json.encode(req)
end
function adapter.transform_response(raw_body)
local ok, resp = pcall(json.decode, raw_body)
if not ok or resp == nil then return raw_body end
local unified = {
content = "",
finish_reason = "",
token_usage = { prompt = 0, completion = 0, total = 0 }
}
if type(resp.usage) == "table" then
unified.token_usage.prompt = resp.usage.prompt_tokens or 0
unified.token_usage.completion = resp.usage.completion_tokens or 0
unified.token_usage.total = resp.usage.total_tokens or 0
local hit = 0
if type(resp.usage.prompt_tokens_details) == "table" and resp.usage.prompt_tokens_details.cached_tokens ~= nil then
hit = resp.usage.prompt_tokens_details.cached_tokens
unified.token_usage.prompt_tokens_details = { cached_tokens = hit }
end
if (resp.usage.prompt_cache_hit_tokens or 0) > 0 then
unified.token_usage.prompt_cache_hit_tokens = resp.usage.prompt_cache_hit_tokens
unified.token_usage.prompt_cache_miss_tokens = resp.usage.prompt_cache_miss_tokens or 0
if hit == 0 then
unified.token_usage.prompt_tokens_details = { cached_tokens = resp.usage.prompt_cache_hit_tokens }
end
end
end
if type(resp.choices) == "table" and #resp.choices > 0 then
local ch = resp.choices[1]
if type(ch.message) == "table" then
unified.content = ch.message.content or ""
local reasoning = ch.message.reasoning_content or ch.message.reasoning
if reasoning then
unified.reasoning_content = reasoning
end
if type(ch.message.tool_calls) == "table" then
local tcs = {}
for _, tc in ipairs(ch.message.tool_calls) do
local args_ok, args = pcall(json.decode, tc["function"].arguments)
if not args_ok then args = {} end
table.insert(tcs, {
id = tc.id,
type = tc.type or "function",
name = tc["function"].name,
arguments = args
})
end
unified.tool_calls = tcs
end
end
unified.finish_reason = ch.finish_reason or ""
end
return json.encode(unified)
end
function adapter.transform_stream_chunk(raw_chunk)
local ok, chunk = pcall(json.decode, raw_chunk)
if not ok then return "" end
-- OpenAI-style streams may attach usage to a chunk with empty choices
-- (the final usage chunk). Preserve it; the gateway emits it as the
-- terminal usage chunk. Note: keys must match Go's TokenUsage json tags
-- (prompt/completion/total); the gateway re-emits standard *_tokens.
local uses = nil
if type(chunk.usage) == "table" then
uses = {
prompt = chunk.usage.prompt_tokens or chunk.usage.prompt or 0,
completion = chunk.usage.completion_tokens or chunk.usage.completion or 0,
total = chunk.usage.total_tokens or chunk.usage.total or 0,
}
if type(chunk.usage.prompt_tokens_details) == "table" and chunk.usage.prompt_tokens_details.cached_tokens ~= nil then
uses.prompt_tokens_details = { cached_tokens = chunk.usage.prompt_tokens_details.cached_tokens }
elseif (chunk.usage.prompt_cache_hit_tokens or 0) > 0 then
uses.prompt_cache_hit_tokens = chunk.usage.prompt_cache_hit_tokens
uses.prompt_cache_miss_tokens = chunk.usage.prompt_cache_miss_tokens or 0
uses.prompt_tokens_details = { cached_tokens = chunk.usage.prompt_cache_hit_tokens }
end
end
if not chunk.choices or #chunk.choices == 0 then
if uses ~= nil then
-- usage-only chunk is not a content/finish signal; the gateway
-- emits its own terminal stop chunk and merges this usage.
return json.encode({ usage = uses, done = false })
end
return ""
end
local delta = chunk.choices[1].delta or {}
local fr = chunk.choices[1].finish_reason
local finish = (type(fr) == "string" and fr ~= "") and fr or nil
local unified = {
content = delta.content or "",
done = (finish ~= nil)
}
if finish then
unified.finish_reason = finish
end
if uses ~= nil then
unified.usage = uses
end
-- zen 用 reasoning 字段承载推理文本OpenAI 惯例是 reasoning_content
local reasoning = delta.reasoning_content or delta.reasoning
if reasoning then
unified.reasoning_content = reasoning
end
if delta.tool_calls then
-- pass raw streaming fragments through; OpenAI clients accumulate index+id+name+arguments
unified.tool_calls = delta.tool_calls
end
return json.encode(unified)
end
-- 错误收敛可选钩子zen 错误信封固定为 {error={type,message}}
-- 免费池限流 FreeUsageLimitError 单独标注。返回 nil 走通用兜底。
function adapter.transform_error(status, body)
local ok, resp = pcall(json.decode, body)
if not ok or type(resp) ~= "table" then return nil end
local e = resp.error
if type(e) ~= "table" then return nil end
if e.type == "FreeUsageLimitError" then
return "zen free pool quota exhausted"
end
return e.message
end
return adapter