diff --git a/.claude/settings.local.json b/.claude/settings.local.json
deleted file mode 100644
index 6fccb8f..0000000
--- a/.claude/settings.local.json
+++ /dev/null
@@ -1,15 +0,0 @@
-{
-  "permissions": {
-    "allow": [
-      "Bash(cat:*)",
-      "Bash(for f in ~/.local/share/opencode/storage/part/*/*)",
-      "Bash(do grep -l \"\"type\"\":\"\"reasoning\"\" $f)",
-      "Bash(done)",
-      "WebSearch",
-      "WebFetch(domain:ai-sdk.dev)",
-      "Bash(npm run typecheck:*)"
-    ],
-    "deny": [],
-    "ask": []
-  }
-}
diff --git a/.gitignore b/.gitignore
index 6fcd193..c4c6365 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,7 +27,6 @@ Thumbs.db
 
 # OpenCode
 .opencode/
-AGENTS.md
 
 # Tests (local development only)
 tests/
diff --git a/index.ts b/index.ts
index 0b32e31..f30b041 100644
--- a/index.ts
+++ b/index.ts
@@ -42,6 +42,18 @@ const plugin: Plugin = (async (ctx) => {
                 workingDirectory: ctx.directory
             }),
         } : undefined,
+        config: async (opencodeConfig) => {
+            // Add prune to primary_tools by mutating the opencode config
+            // This works because config is cached and passed by reference
+            if (config.strategies.pruneTool.enabled) {
+                const existingPrimaryTools = opencodeConfig.experimental?.primary_tools ?? []
+                opencodeConfig.experimental = {
+                    ...opencodeConfig.experimental,
+                    primary_tools: [...existingPrimaryTools, "prune"],
+                }
+                logger.info("Added 'prune' to experimental.primary_tools via config mutation")
+            }
+        },
     }
 }) satisfies Plugin
 
diff --git a/lib/hooks.ts b/lib/hooks.ts
index b3dc9da..88acd88 100644
--- a/lib/hooks.ts
+++ b/lib/hooks.ts
@@ -17,11 +17,15 @@ export function createChatMessageTransformHandler(
         input: {},
         output: { messages: WithParts[] }
     ) => {
-        checkSession(state, logger, output.messages);
+        checkSession(client, state, logger, output.messages);
+        if (state.isSubAgent) {
+            return
+        }
+
         syncToolCache(state, config, logger, output.messages);
 
 
-        deduplicate(state, logger, config, output.messages)
+        deduplicate(client, state, logger, config, output.messages)
 
         prune(state, logger, config, output.messages)
 
diff --git a/lib/state/state.ts b/lib/state/state.ts
index 6682d6f..8edbf52 100644
--- a/lib/state/state.ts
+++ b/lib/state/state.ts
@@ -2,8 +2,10 @@ import type { SessionState, ToolParameterEntry, WithParts } from "./types"
 import type { Logger } from "../logger"
 import { loadSessionState } from "./persistence"
 import { getLastUserMessage } from "../messages/utils"
+import { isSubAgentSession } from "../utils"
 
 export const checkSession = (
+    client: any,
     state: SessionState,
     logger: Logger,
     messages: WithParts[]
@@ -19,6 +21,7 @@ export const checkSession = (
     if (state.sessionId === null || state.sessionId !== lastSessionId) {
         logger.info(`Session changed: ${state.sessionId} -> ${lastSessionId}`)
         ensureSessionInitialized(
+            client,
             state,
             lastSessionId,
             logger
@@ -31,6 +34,7 @@ export const checkSession = (
 export function createSessionState(): SessionState {
     return {
         sessionId: null,
+        isSubAgent: false,
         prune: {
             toolIds: []
         },
@@ -45,6 +49,7 @@ export function createSessionState(): SessionState {
 
 export function resetSessionState(state: SessionState): void {
     state.sessionId = null
+    state.isSubAgent = false
     state.prune = {
         toolIds: []
     }
@@ -57,6 +62,7 @@ export function resetSessionState(state: SessionState): void {
 }
 
 export async function ensureSessionInitialized(
+    client: any,
     state: SessionState,
     sessionId: string,
     logger: Logger
@@ -72,6 +78,10 @@ export async function ensureSessionInitialized(
     resetSessionState(state)
     state.sessionId = sessionId
 
+    const isSubAgent = await isSubAgentSession(client, sessionId)
+    state.isSubAgent = isSubAgent
+    logger.info("isSubAgent = " + isSubAgent)
+
     // Load session data from storage
     const persisted = await loadSessionState(sessionId, logger)
     if (persisted === null) {
diff --git a/lib/state/types.ts b/lib/state/types.ts
index 750ca38..f7353e0 100644
--- a/lib/state/types.ts
+++ b/lib/state/types.ts
@@ -25,6 +25,7 @@ export interface Prune {
 
 export interface SessionState {
     sessionId: string | null
+    isSubAgent: boolean
     prune: Prune
     stats: SessionStats
     toolParameters: Map<string, ToolParameterEntry>
diff --git a/lib/strategies/deduplication.ts b/lib/strategies/deduplication.ts
index f58a13a..f0887c2 100644
--- a/lib/strategies/deduplication.ts
+++ b/lib/strategies/deduplication.ts
@@ -9,6 +9,7 @@ import { calculateTokensSaved } from "../utils"
  * Modifies the session state in place to add pruned tool call IDs.
  */
 export const deduplicate = (
+    client: any,
     state: SessionState,
     logger: Logger,
     config: PluginConfig,
diff --git a/lib/strategies/on-idle.ts b/lib/strategies/on-idle.ts
new file mode 100644
index 0000000..e69de29
diff --git a/lib/strategies/prune-tool.ts b/lib/strategies/prune-tool.ts
index 08e680c..83d4ff5 100644
--- a/lib/strategies/prune-tool.ts
+++ b/lib/strategies/prune-tool.ts
@@ -60,7 +60,7 @@ export function createPruneTool(
                 return "No numeric IDs provided. Format: [reason, id1, id2, ...] where reason is 'completion', 'noise', or 'consolidation'."
             }
 
-            await ensureSessionInitialized(state, sessionId, logger)
+            await ensureSessionInitialized(ctx.client, state, sessionId, logger)
 
             // Fetch messages to calculate tokens and find current agent
             const messagesResponse = await client.session.messages({
diff --git a/lib/utils.ts b/lib/utils.ts
index 844edfb..471729c 100644
--- a/lib/utils.ts
+++ b/lib/utils.ts
@@ -60,7 +60,7 @@ export function formatTokenCount(tokens: number): string {
 /**
  * Checks if a session is a subagent session by looking for a parentID.
  */
-export async function isSubagentSession(client: any, sessionID: string): Promise<boolean> {
+export async function isSubAgentSession(client: any, sessionID: string): Promise<boolean> {
     try {
         const result = await client.session.get({ path: { id: sessionID } })
         return !!result.data?.parentID