plugins: config-defined agents are missing during agent transforms #51598

Summary

On OpenCode 2.0.18, agents declared in configuration are absent from both ctx.agent.list() and the AgentEditor during plugin setup transforms, but appear in /api/agent after setup. This prevents plugins from safely validating or applying policy to configured custom agents. Please clarify whether this lifecycle is intentional and, if so, provide a supported post-configuration transformation or validation path.

Environment

• opencode version: 2.0.18
• OS: Linux 6.17.0-1021-nvidia, aarch64
• Terminal: xterm-256color (TERM_PROGRAM and COLORTERM unavailable)
• Shell: /bin/bash
• Install/channel: latest
• Active plugins: local KSI harness (failed during agent.transform), Superpowers, @prevalentware/[email protected], OpenChamber agent tool

Reproduction

1. Configure a custom agent, for example developer, under agents with mode: "subagent".
2. Load a plugin whose setup(ctx) logs await ctx.agent.list() and registers ctx.agent.transform. In the callback, log editor.list() and editor.get("developer").
3. After setup, query GET /api/agent for the same location.

Expected Behavior

Configuration-defined agents should be available while plugin agent transforms run. If transforms intentionally run before configured agents are materialized, the plugin API should document a supported later phase or another reliable way to validate and update configured agents without implicitly creating undeclared IDs.

Actual Behavior

During plugin setup, both ctx.agent.list() and editor.list() expose built-in agents only, and editor.get("developer") is undefined. In the isolated reproduction, the editor listed build, compaction, explore, general, plan, summary, and title. After setup, /api/agent includes the configured developer agent.

A policy plugin that fails closed when a required configured agent ID is unavailable is disabled. The observed KSI error was:

KSI V2: define these agent IDs in OpenCode's agents config before loading the plugin: design, developer, test-runner, reviewer, research, design-critic

Additional Context

Reproduced consistently on OpenCode 2.0.18 using a loopback server with separate temporary HOME/XDG configuration and data directories and a minimal agent/plugin configuration. No provider/auth configuration was present and no provider calls were made. The same failure remained after a shared-service restart and a location reload. The custom IDs were present in the configuration and appeared in the later API catalog.