[FEATURE]: Feature Request / Bug: Per-agent compaction control breaks local model workflows #34510

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Describe the enhancement you want to request

Feature Request / Bug: Per-agent compaction control breaks local model workflows

OpenCode version: 1.17.11
OS: Windows 11

Problem

Auto-compaction cannot be disabled per-agent. The compaction: { "enabled": false } field in agent config is currently ignored — compaction still triggers globally regardless of agent-level settings.

This creates an infinite loop when using local models (LM Studio / Ollama) as agents:

1. Local model responds and finishes naturally (finish === "stop")
2. Auto-compaction triggers
3. OpenCode injects a synthetic "Continue..." message
4. Local model responds again
5. Loop repeats indefinitely

This is especially problematic because local models have small context windows (8K–14K tokens). The global system prompt + instructions already consume most of the available context, leaving almost no room before compaction fires.

Current workaround

Setting compaction: { "auto": false } globally disables auto-compaction for all agents, including cloud agents that benefit from it. This is a regression for cloud workflows.

Expected behavior

compaction: { "enabled": false } in an agent config should prevent auto-compaction from triggering for that specific agent session, consistent with how other per-agent overrides already work (model, tools, steps, temperature, permission).

Proposed config

"agent": {
  "coder-local": {
    "model": "lmstudio/qwen/qwen3.5-9b",
    "compaction": { "enabled": false }
  },
  "lexis-one": {
    "model": "opencode-go/kimi-k2.6"
    // compaction uses global default
  }
}

Related issues

• [FEATURE]: Per-agent compaction config (disable compaction for specific agents) #16375 — Per-agent compaction config (feature request, open)
• Auto-compaction infinite loop when assistant ended its turn (finish !== tool-calls) #15533 — Auto-compaction infinite loop when finish === "stop" (bug, open)
• Stuck in compaction loop, no matter what i do it doesn't read AGENTS.md #19410 — Stuck in compaction loop

Why this matters

Local model support is one of OpenCode's key differentiators. Without per-agent compaction control, local models are effectively unusable in multi-turn sessions, which defeats the purpose of having local agent configurations.