Problem

/status shows 🧹 Compactions: 0 for agents using plugin context engines (e.g. mem-engine, lossless-claw), even after hundreds of successful compactions.

Root Cause

The compactionCount displayed by /status can only be incremented through two paths:

1. Mid-stream auto-compaction — when the built-in compaction fires during an agent run, autoCompactionCount increments and flows into agentMeta.compactionCount, which updateSessionStoreAfterAgentRun reads. Plugin context engines that own compaction (ownsCompaction: true) bypass this path entirely because their assemble() keeps context within budget, preventing overflow.

2. /compact slash command or overflow recovery — calls contextEngine.compact(), and if it returns { ok: true, compacted: true }, incrementCompactionCount() fires on the session store. This works, but /new resets compactionCount to 0, and overflow rarely triggers because assemble() handles it proactively.

Neither path captures leaf compactions — the primary compaction mechanism for plugin context engines. These run in afterTurn() (background, fire-and-forget), and the ContextEngine.afterTurn() interface:

• Returns Promise<void> — return value is ignored by OpenClaw
• Receives no callback to signal compaction activity
• Has no access to the session store

Evidence

• compaction_events table: 1,948 incremental leaf drains, 146 successful compactions
• Session store: compactionCount: 0 for all plugin-engine sessions
• main agent (legacy engine): compactionCount: 38 — works because it uses mid-stream auto-compaction

Suggested Fix

Add a compaction notification channel to the afterTurn contract. Options:

Option A (callback): Pass notifyCompaction(count?: number) in afterTurn params. Plugin calls it after each successful leaf/proactive compaction.

Option B (return value): Change afterTurn return type to Promise<void | { compactionCount?: number }>. OpenClaw reads and increments.

Option C (direct read): /status queries the context engine's own compaction tracking (e.g. via a new getStats() method on the ContextEngine interface).

Option A is probably cleanest — minimal contract change, plugin controls granularity.

Affected

• Any ContextEngine plugin with ownsCompaction: true
• Known: mem-engine, lossless-claw
• OpenClaw version: 2026.3.13 (61d171a)