OpenCode Agent Context Pruning (ACP)

Automatically reduces token usage in OpenCode by removing redundant or obsolete content from conversation history.

⚡ Performance Fork: Optimized with aggressive defaults and four additional pruning strategies: Prune Thinking, Head-Tail Truncation, Read Consolidation, and Placeholder Compression.

Pruning Architecture

graph TD
    A[New Turn] --> B{Strategy Type}

    subgraph "Automatic (Zero Cost)"
    B --> C[Deduplication]
    B --> D[Supersede Writes]
    B --> E[Purge Errors]
    B --> F[Read Consolidation]
    B --> G[Prune Thinking]
    B --> H[Head-Tail Truncation]

    C --> |Removes identical calls| I[Context Saved]
    D --> |Prunes writes after reads| I
    E --> |Strips failed call inputs| I
    F --> |Stale reads point to new| I
    G --> |Strips reasoning/thinking| I
    H --> |Middle-out truncation| I
    end

    subgraph "LLM-Driven (High Precision)"
    A --> J[AI Nudge]
    J --> |Suggests Cleanup| K{Agent Action}
    K --> L[Discard Tool]
    K --> M[Extract Tool]
    L --> |Direct removal| I
    M --> |Summarize then remove| I
    end

Installation

Add to your OpenCode config:

// opencode.jsonc
{
    "plugin": ["@tuanhung303/opencode-acp@latest"],
}

Core Strategies

🚀 Automatic Strategies (Instant & Free)

• Head-Tail Truncation (⚡ Default): Preserves the first 20% and last 30% of tool outputs, removing the middle section. Optimized for the "Lost in the Middle" phenomenon.
• Read Consolidation: When the same file is read multiple times, older outputs are replaced with pointers to the newest version.
• Prune Thinking: Strips ephemeral reasoning blocks (Claude <thinking> or OpenAI reasoning) from older messages.
• Supersede Writes: Automatically prunes write tool inputs once a subsequent read of the same file confirms the state.
• Deduplication: Eliminates identical tool calls while preserving the most recent result.
• Purge Errors: Automatically clears inputs from failed tool calls after 2 turns.

🧠 LLM-Driven Tools

• discard: The agent manually removes tool content that is no longer relevant to the current task.
• extract: The agent distills valuable findings into a concise summary before purging the raw data.

Configuration Defaults

This fork utilizes more aggressive defaults than the upstream version to maximize context efficiency:

Configuration File

The plugin automatically creates a config at ~/.config/opencode/acp.jsonc. You can also use project-level overrides in .opencode/acp.jsonc.

{
    "strategies": {
        "pruneThinking": { "enabled": true, "delayTurns": 1 },
        "headTailTruncation": {
            "enabled": true,
            "headRatio": 0.2,
            "tailRatio": 0.3,
        },
        "readConsolidation": { "enabled": true },
    },
}

Commands

• /acp context: Visualize token usage and savings.
• /acp stats: Cumulative efficiency report.
• /acp sweep: Force a manual cleanup of the current session.

License

MIT