fix: case-sensitive protected tools, cross-session dedup, unbounded cache

Fixes from PR #57 applied to refactored file structure:
- Normalize tool names to lowercase for protected tools check
- Scope deduplication to tool IDs from current request only
- Add trimToolParametersCache() with 500-entry FIFO eviction

Closes #57

Author: Tarquinen

lib/core/strategies/deduplication.ts

@@ -17,7 +17,8 @@ export const deduplicationStrategy: PruningStrategy = {
 
         const deduplicatableIds = unprunedIds.filter(id => {
             const metadata = toolMetadata.get(id)
-            return !metadata || !protectedTools.includes(metadata.tool)
+            const protectedToolsLower = protectedTools.map(t => t.toLowerCase())
+            return !metadata || !protectedToolsLower.includes(metadata.tool.toLowerCase())
         })
 
         for (const id of deduplicatableIds) {

lib/fetch-wrapper/index.ts

@@ -8,6 +8,7 @@ import { handleGemini } from "./gemini"
 import { handleOpenAIResponses } from "./openai-responses"
 import { runStrategies } from "../core/strategies"
 import { accumulateGCStats } from "./gc-tracker"
+import { trimToolParametersCache } from "../state/tool-cache"
 
 export type { FetchHandlerContext, FetchHandlerResult, SynthPrompts } from "./types"
 
@@ -55,6 +56,9 @@ export function installFetchWrapper(
                 const inputUrl = typeof input === 'string' ? input : 'URL object'
                 let modified = false
 
+                // Capture tool IDs before handlers run to track what gets cached this request
+                const toolIdsBefore = new Set(state.toolParameters.keys())
+
                 // Try each format handler in order
                 // OpenAI Chat Completions & Anthropic style (body.messages)
                 if (body.messages && Array.isArray(body.messages)) {
@@ -80,10 +84,12 @@ export function installFetchWrapper(
                     }
                 }
 
-                // Run strategies after handlers have populated toolParameters cache
+                // Run strategies only on tool IDs cached during THIS request (not cross-session)
                 const sessionId = state.lastSeenSessionId
-                if (sessionId && state.toolParameters.size > 0) {
-                    const toolIds = Array.from(state.toolParameters.keys())
+                const toolIdsAfter = Array.from(state.toolParameters.keys())
+                const cachedToolIds = toolIdsAfter.filter(id => !toolIdsBefore.has(id))
+                if (sessionId && cachedToolIds.length > 0) {
+                    const toolIds = cachedToolIds
                     const alreadyPruned = state.prunedIds.get(sessionId) ?? []
                     const alreadyPrunedLower = new Set(alreadyPruned.map(id => id.toLowerCase()))
                     const unpruned = toolIds.filter(id => !alreadyPrunedLower.has(id.toLowerCase()))
@@ -102,6 +108,9 @@ export function installFetchWrapper(
                             accumulateGCStats(state, sessionId, result.prunedIds, body, logger)
                         }
                     }
+
+                    // Trim cache to prevent unbounded memory growth
+                    trimToolParametersCache(state)
                 }
 
                 if (modified) {

lib/state/tool-cache.ts

@@ -59,3 +59,23 @@ export function cacheToolParametersFromInput(
         }
     }
 }
+
+/** Maximum number of entries to keep in the tool parameters cache */
+const MAX_TOOL_CACHE_SIZE = 500
+
+/**
+ * Trim the tool parameters cache to prevent unbounded memory growth.
+ * Uses FIFO eviction - removes oldest entries first.
+ */
+export function trimToolParametersCache(state: PluginState): void {
+    if (state.toolParameters.size <= MAX_TOOL_CACHE_SIZE) {
+        return
+    }
+
+    const keysToRemove = Array.from(state.toolParameters.keys())
+        .slice(0, state.toolParameters.size - MAX_TOOL_CACHE_SIZE)
+
+    for (const key of keysToRemove) {
+        state.toolParameters.delete(key)
+    }
+}