session/set_config_option unimplemented in opencode@0.2.x; opencode@0.3.x is blocked by an agentos-core package-format mismatch

[nateslabach]

Summary

Using @agentos-software/opencode with a non-default model provider (e.g. OpenRouter) is currently impossible in any published version:

• On opencode@0.2.7 (latest stable), the ACP method that actually changes the selected model, session/set_config_option, has no working implementation - it returns "Method not found" even though the config option is declared as writable.
  • The next version line, opencode@0.3.1/0.3.2 (published on npm, not yet tagged latest), appears to fix this, but its package registration format is incompatible with every currently-published @rivet-dev/agentos-core (checked both latest @ 0.2.15 and rc @ 0.2.16-rc.2) - AgentOs.create() throws immediately:

agentOS package ref uses removed field "packageDir" (value: ".../node_modules/@agentos-software/opencode/dist/package/"); packages are referenced by a single packagePath — update the package (rebuild @agentos-software/* dependencies) or pass { packagePath }

Repro (0.2.7 - model selection broken)

import { AgentOs } from "@rivet-dev/agentos-core";
import opencode from "@agentos-software/opencode"; // 0.2.7

const vm = await AgentOs.create({ software: [opencode], database: { type: "sqlite_file", path: "/tmp/repro.sqlite" } });
await vm.openSession({ sessionId: "s1", agent: "opencode", env: { OPENROUTER_API_KEY: "..." } });
await vm.setSessionConfigOption({ sessionId: "s1", optionId: "model", value: "openrouter/anthropic/claude-haiku-4.5" });
// throws: Method not found

Root cause traced in the bundled source (@agentos-software/opencode/dist/opencode-acp/acp.js): the ACP routing for session/set_config_option exists, but the underlying setSessionConfigOption implementation it delegates to isn't wired up to actually change the model in this build.

Repro (0.3.2 - blocked before it even gets there)

npm install @agentos-software/opencode@0.3.2
Then any AgentOs.create({ software: [opencode], ... }) throws the packageDir/packagePath error above, before a session can even open. Same result against @rivet-dev/agentos-core@0.2.16-rc.2.

Impact

Any self-hosted setup using OpenCode as a harness with a custom model provider is stuck — can't select a model on 0.2.x, can't even boot on 0.3.x. This also blocks anything relying on OpenCode specifically for its MCP tool-calling support, since no prompt can complete at all regardless of MCP.

Ask

Either:

1. Fix session/set_config_option's underlying implementation in the 0.2.x line, or
2. Publish an @rivet-dev/agentos-core version that supports 0.3.x's packagePath format (as latest or rc), so the fix in 0.3.x is actually usable.

Happy to provide a minimal repro repo if useful.

[nateslabach]

Update: Tested a workaround (using Anthropic key directly instead of routing through OpenRouter), since the default model config value is already anthropic/claude-sonnet-... - so this avoids session/set_config/option entirely). Found two more issues:

1. Session bootstrap hangs indefinitely when both an env-var-based provider (ANTHROPIC_API_KEY) and an auth.json-configured provider (OpenRouter, via a written ~/.local/share/opencode/auth.json) are present at the same time. session/new never responds — no error, just hangs until the caller's own timeout fires:

timed out waiting for ACP response id=2; no session/cancel notification for bootstrap request; recent_activity=["sent request session/new id=2"]
Removing the OpenRouter credential (env var + auth.json) and leaving only ANTHROPIC_API_KEY lets the session open normally. Whatever's resolving providers during bootstrap doesn't handle multiple valid credentials existing simultaneously gracefully - it should either pick one deterministically or fail fast with a clear error, not hang.

2. With only ANTHROPIC_API_KEY set (session opens fine), the ACP adapter process itself crashes the moment a real prompt is sent: ACP adapter process acp-agent-3 exited with code 1 before response id=3; recent_activity=["sent request session/prompt id=3"]; adapter_stderr="...Error: null". No useful error message, and the process dies rather than returning a normal ACP error response.

So even sidestepping the original model-selection bug entirely OpenCode can't currently complete a real prompt via either provider path in this installed version