pre_compact_sync · Session Buddy MCP: Risk & Policy

WHAT IT DOES

What pre_compact_sync does on Session Buddy

AI agents use pre_compact_sync to create or update resources in Session Buddy — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Session Buddy environment.

WHY IT NEEDS A POLICY

Why pre_compact_sync needs a policy

This tool writes/persists session state data to storage before a compaction event. It is a Write operation (saving/updating state), not destructive since it preserves data rather than deleting it. Severity is medium because misuse could corrupt session state or cause data inconsistencies, but it doesn't delete or execute arbitrary code.

From the tool's definition 'Sync session state before context compaction' — performs a state synchronization (write) operation prior to compaction

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

pre_compact_sync Rate-limited

pre_compact_sync stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "pre_compact_sync": {
      "limits": [
        {
          "counter": "pre_compact_sync_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Session Buddy, so you can run agents against it safely.

FAQ

Questions about pre_compact_sync

What does the pre_compact_sync tool do? +

Sync session state before context compaction (called via PreCompactHook). It is categorised as a Write tool in the Session Buddy MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on pre_compact_sync? +

Register the Session Buddy MCP server in PolicyLayer and add a rule for pre_compact_sync: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Session Buddy. Nothing to install.

What risk level is pre_compact_sync? +

pre_compact_sync is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit pre_compact_sync? +

Yes. Add a rate_limit block to the pre_compact_sync rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block pre_compact_sync completely? +

Set action: deny in the PolicyLayer policy for pre_compact_sync. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides pre_compact_sync? +

pre_compact_sync is provided by the Session Buddy MCP server (lesleslie/session-buddy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.