fix: skip DCP injection for internal agents (title, summary, compaction)

Detect internal agent sessions by their system prompt signatures and skip
injecting context management prompts. This prevents wasting tokens and
confusing small models used for title generation and conversation summaries.

Fixes #218

Author: Tarquinen

index.ts

@@ -30,6 +30,21 @@ const plugin: Plugin = (async (ctx) => {
             _input: unknown,
             output: { system: string[] },
         ) => {
+            const systemText = output.system.join("\n")
+            const internalAgentSignatures = [
+                "You are a title generator",
+                "You are a helpful AI assistant tasked with summarizing conversations",
+                "Summarize what was done in this conversation",
+            ]
+            if (internalAgentSignatures.some((sig) => systemText.includes(sig))) {
+                logger.info("Skipping DCP injection for internal agent")
+                state.isInternalAgent = true
+                return
+            }
+
+            // Reset flag for normal sessions
+            state.isInternalAgent = false
+
             const discardEnabled = config.tools.discard.enabled
             const extractEnabled = config.tools.extract.enabled
 

lib/hooks.ts

@@ -15,7 +15,7 @@ export function createChatMessageTransformHandler(
     return async (input: {}, output: { messages: WithParts[] }) => {
         await checkSession(client, state, logger, output.messages)
 
-        if (state.isSubAgent) {
+        if (state.isSubAgent || state.isInternalAgent) {
             return
         }
 

lib/state/state.ts

@@ -43,6 +43,7 @@ export function createSessionState(): SessionState {
     return {
         sessionId: null,
         isSubAgent: false,
+        isInternalAgent: false,
         prune: {
             toolIds: [],
         },
@@ -61,6 +62,7 @@ export function createSessionState(): SessionState {
 export function resetSessionState(state: SessionState): void {
     state.sessionId = null
     state.isSubAgent = false
+    state.isInternalAgent = false
     state.prune = {
         toolIds: [],
     }

lib/state/types.ts

@@ -12,7 +12,7 @@ export interface ToolParameterEntry {
     parameters: any
     status?: ToolStatus
     error?: string
-    turn: number // Which turn (step-start count) this tool was called on
+    turn: number
 }
 
 export interface SessionStats {
@@ -27,11 +27,12 @@ export interface Prune {
 export interface SessionState {
     sessionId: string | null
     isSubAgent: boolean
+    isInternalAgent: boolean
     prune: Prune
     stats: SessionStats
     toolParameters: Map<string, ToolParameterEntry>
     nudgeCounter: number
     lastToolPrune: boolean
     lastCompaction: number
-    currentTurn: number // Current turn count derived from step-start parts
+    currentTurn: number
 }