Clear tool caches on compaction and add stale entry warning

- Clear toolParameters and prune.toolIds when compaction is detected
- Add warning log when tool is in cache but not in toolIdList
- Stale tool data from pre-compaction no longer lingers in state

Author: Tarquinen

lib/messages/prune.ts

@@ -27,6 +27,10 @@ const buildPrunableToolsList = (
             return
         }
         const numericId = toolIdList.indexOf(toolCallId)
+        if (numericId === -1) {
+            logger.warn(`Tool in cache but not in toolIdList - possible stale entry`, { toolCallId, tool: toolParameterEntry.tool })
+            return
+        }
         const paramKey = extractParameterKey(toolParameterEntry.tool, toolParameterEntry.parameters)
         const description = paramKey ? `${toolParameterEntry.tool}, ${paramKey}` : toolParameterEntry.tool
         lines.push(`${numericId}: ${description}`)

lib/state/state.ts

@@ -31,7 +31,10 @@ export const checkSession = async (
     const lastCompactionTimestamp = findLastCompactionTimestamp(messages)
     if (lastCompactionTimestamp > state.lastCompaction) {
         state.lastCompaction = lastCompactionTimestamp
-        logger.info("Detected compaction from messages", { timestamp: lastCompactionTimestamp })
+        // Clear stale tool data - these tools no longer exist in context
+        state.toolParameters.clear()
+        state.prune.toolIds = []
+        logger.info("Detected compaction from messages - cleared tool cache", { timestamp: lastCompactionTimestamp })
     }
 }