[BUG] opencode acp session/new fails with "No models available" due to Context.empty()

[SXongin]

Description

opencode acp 的 session/new 始终返回 -32603 Internal error: "No models available"，
即使 provider 已正确配置且 opencode run 可以正常使用。

这是阻断了 cc-connect 等 ACP bridge 工具通过 ACP 协议对接 OpenCode 的关键 bug。

Environment

• OpenCode: 1.15.10 (npm)
• OS: Linux (Arch, WSL)
• Config: ~/.config/opencode/opencode.json 已配置 DeepSeek provider，opencode run 正常工作

Reproduction

(echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":1}}'
 sleep 2
 echo '{"jsonrpc":"2.0","id":2,"method":"session/new","params":{"cwd":"/tmp","mcpServers":[]}}'
 sleep 8) | timeout 15 opencode acp --cwd /tmp 2>&1

Actual Output

{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":1,...}}   ← initialize OK
Error handling request {
  jsonrpc: "2.0", id: 2, method: "session/new", ...
} {
  code: -32603,
  message: "Internal error",
  data: { details: "No models available" }                     ← FAILS
}

Root Cause Analysis

问题出在 src/server/routes/instance/index.ts。
ACP 命令启动内部 HTTP 服务器时，InstanceRoutes 使用 Context.empty() 创建路由处理器，
而不是正确初始化的 Effect 服务上下文。导致所有 SDK API 调用
（GET /config, /config/providers, /session）返回 502 Bad Gateway，
session/new 因此报 "No models available"。

使用 ExperimentalHttpApiServer.context 替代 Context.empty() 可以修复此问题。

Note

这个问题不同于已关闭的 #25568（PR #25591 修复的是 internal HTTP client 的 auth token 传递问题）。
即使 auth 正确，Context.empty() 导致的路由 502 仍然存在。

Impact

此 bug 阻断了 OpenCode 通过 ACP 协议与 cc-connect 等 bridge 工具的完整集成。cc-connect 的 ACP 适配器已经实现了完整的交互式权限转发（session/request_permission → 飞书/Telegram Allow/Deny 弹窗），但由于此 bug 无法创建 session。参见 chenhg5/cc-connect#1100。

[SXongin]

PR opened: #31090 — replaces Context.empty() with ExperimentalHttpApiServer.context

[SXongin]

Update: upstream PR #25667 ("research: delete Hono backend") has completely removed the old Hono backend that contained the Context.empty() issue. The ACP has been rewritten from scratch with dedicated modules under packages/opencode/src/acp/, using @agentclientprotocol/sdk + @opencode-ai/sdk/v2. This issue is effectively resolved by the refactoring — closing the associated PR #31090 as the targeted code no longer exists.

Note: OpenCode v1.16.2+ (stable) should include the new ACP implementation.

[SXongin]

Closing: upstream PR #25667 ("research: delete Hono backend") has completely removed the old Hono backend including the file this issue targeted. The ACP has been rewritten from scratch with dedicated modules under packages/opencode/src/acp/, using @agentclientprotocol/sdk + @opencode-ai/sdk/v2. This bug no longer exists in the current codebase (v1.16.2+).

Note: the new ACP has a different bug (#31091) — session/new returns -32603 Internal error on Linux/WSL — but the original Context.empty() issue is resolved by deletion.