[Bug] OpenCode Go requests rejected with 400 "Request is missing x-opencode-session"

[gilsion0929]

Affected area

AI providers and models

What happened?

Requests to the OpenCode Go provider are rejected by the gateway with HTTP 400:
Error: 400 Error from provider (Console Go): Request is missing x-opencode-session and cannot be routed efficiently.
prime-agent never sends the x-opencode-session header that OpenCode Go requires, so the opencode-go provider is unusable.
Root cause: The bundled openai-completions provider only emits session-affinity headers when compat.sendSessionAffinityHeaders is true, and even then it sends session_id, x-client-request-id, and x-session-affinity — never x-opencode-session. detectCompat() defaults sendSessionAffinityHeaders: false, and the built-in opencode-go model definitions do not set it, so no session header is sent at all for the Go provider.
if (sessionId && compat.sendSessionAffinityHeaders) {
headers.session_id = sessionId;
headers["x-client-request-id"] = sessionId;
headers["x-session-affinity"] = sessionId;
}
"opencode-go": {
"deepseek-v4-flash": {
api: "openai-completions",
provider: "opencode-go",
baseUrl: "https://opencode.ai/zen/go/v1",
compat: { "requiresReasoningContentOnAssistantMessages": true, "thinkingFormat": "deepseek" },
...
}
}

Steps to reproduce

1. Run prime-agent with the built-in model opencode-go/deepseek-v4-flash (default provider opencode-go).
2. Send any message to start a conversation.
3. Observe the request fails with: 400 Error from provider (Console Go): Request is missing x-opencode-session and cannot be routed efficiently.

Expected behavior

For the opencode-go provider, prime-agent should send the x-opencode-session header (with a stable per-conversation session ID) so OpenCode Go can route and cache efficiently.
Suggested fix: add "opencode-go" to the set of providers that send session-affinity headers, and emit x-opencode-session (in addition to session_id/x-client-request-id/x-session-affinity) for that provider.

Prime Agent version

0.9.3-beta.634.1.bf8894a (also present in 0.9.3-beta.632.1.b9cf467)

Installation method

Stable release installer

Operating system

Windows Subsystem for Linux (WSL)

Operating system version

Ubuntu 24.04.4 LTS

CPU architecture

x86_64 / amd64

Shell and terminal

bash (GNU bash) in a terminal emulator

Additional context

Local workaround (lost on every update): manually patch the bundled openai-completions-*.js to (1) set sendSessionAffinityHeaders: provider === "opencode-go" and (2) add headers["x-opencode-session"] = sessionId; in the session-header block. A proper upstream fix is requested so this survives updates.

[kevinjosethomas]

I’m taking a look at this.

[dzid26]

#2141

[kevinjosethomas]

Merged in #2131; this fix is not released yet.