messages: sanitize visible DCP metadata output

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

Author: ricatix

index.ts

@@ -14,6 +14,7 @@ import {
     createCommandExecuteHandler,
     createSystemPromptHandler,
     createTextCompleteHandler,
+    createToolExecuteAfterHandler,
 } from "./lib/hooks"
 import { configureClientAuth, isSecureMode } from "./lib/auth"
 
@@ -71,6 +72,7 @@ const plugin: Plugin = (async (ctx) => {
             logger.debug("Cached variant from chat.message hook", { variant: input.variant })
         },
         "experimental.text.complete": createTextCompleteHandler(),
+        "tool.execute.after": createToolExecuteAfterHandler(),
         "command.execute.before": createCommandExecuteHandler(
             ctx.client,
             state,

lib/hooks.ts

@@ -11,7 +11,12 @@ import {
     injectExtendedSubAgentResults,
     stripStaleMetadata,
 } from "./messages"
-import { buildToolIdList, isIgnoredUserMessage, stripHallucinations } from "./messages/utils"
+import {
+    buildToolIdList,
+    isIgnoredUserMessage,
+    sanitizeVisibleOutput,
+    stripHallucinations,
+} from "./messages/utils"
 import { checkSession } from "./state"
 import { renderSystemPrompt } from "./prompts"
 import { handleStatsCommand } from "./commands/stats"
@@ -33,9 +38,6 @@ const INTERNAL_AGENT_SIGNATURES = [
     "Summarize what was done in this conversation",
 ]
 
-const DCP_MESSAGE_ID_TAG_REGEX = /<dcp-message-id>(?:m\d+|b\d+)<\/dcp-message-id>/g
-const DCP_SYSTEM_REMINDER_REGEX = /<dcp-system-reminder\b[^>]*>[\s\S]*?<\/dcp-system-reminder>/g
-
 function applyManualPrompt(state: SessionState, messages: WithParts[], logger: Logger): void {
     const pending = state.pendingManualTrigger
     if (!pending) {
@@ -125,7 +127,7 @@ export function createChatMessageTransformHandler(
     prompts: PromptStore,
     hostPermissions: HostPermissionSnapshot,
 ) {
-    return async (input: {}, output: { messages: WithParts[] }) => {
+    return async (_input: {}, output: { messages: WithParts[] }) => {
         await checkSession(client, state, logger, output.messages, config.manualMode.enabled)
 
         syncCompressPermissionState(state, config, hostPermissions, output.messages)
@@ -280,8 +282,16 @@ export function createTextCompleteHandler() {
         _input: { sessionID: string; messageID: string; partID: string },
         output: { text: string },
     ) => {
-        output.text = output.text
-            .replace(DCP_SYSTEM_REMINDER_REGEX, "")
-            .replace(DCP_MESSAGE_ID_TAG_REGEX, "")
+        output.text = sanitizeVisibleOutput(output.text)
+    }
+}
+
+export function createToolExecuteAfterHandler() {
+    return async (
+        _input: { tool: string; sessionID: string; callID: string },
+        output: { title: string; output: string; metadata: unknown },
+    ) => {
+        output.title = sanitizeVisibleOutput(output.title)
+        output.output = sanitizeVisibleOutput(output.output)
     }
 }

lib/messages/inject/inject.ts

@@ -6,9 +6,7 @@ import { formatMessageIdTag } from "../../message-ids"
 import { compressPermission, getLastUserMessage } from "../../shared-utils"
 import { saveSessionState } from "../../state/persistence"
 import {
-    appendIdToTool,
     createSyntheticTextPart,
-    findLastToolPart,
     isIgnoredUserMessage,
 } from "../utils"
 import {
@@ -164,11 +162,6 @@ export const injectMessageIds = (
             continue
         }
 
-        const lastToolPart = findLastToolPart(message)
-        if (lastToolPart && appendIdToTool(lastToolPart, tag)) {
-            continue
-        }
-
         const syntheticPart = createSyntheticTextPart(message, tag)
         const firstToolIndex = message.parts.findIndex((p) => p.type === "tool")
         if (firstToolIndex === -1) {

lib/messages/utils.ts

@@ -61,38 +61,10 @@ export const createSyntheticTextPart = (
         messageID: userInfo.id,
         type: "text" as const,
         text: content,
+        synthetic: true,
     }
 }
 
-type MessagePart = WithParts["parts"][number]
-type ToolPart = Extract<MessagePart, { type: "tool" }>
-
-export const appendIdToTool = (part: ToolPart, tag: string): boolean => {
-    if (part.type !== "tool") {
-        return false
-    }
-    if (part.state?.status !== "completed" || typeof part.state.output !== "string") {
-        return false
-    }
-    if (part.state.output.includes(tag)) {
-        return true
-    }
-
-    part.state.output = `${part.state.output}${tag}`
-    return true
-}
-
-export const findLastToolPart = (message: WithParts): ToolPart | null => {
-    for (let i = message.parts.length - 1; i >= 0; i--) {
-        const part = message.parts[i]
-        if (part.type === "tool") {
-            return part
-        }
-    }
-
-    return null
-}
-
 export function buildToolIdList(state: SessionState, messages: WithParts[]): string[] {
     const toolIds: string[] = []
     for (const msg of messages) {
@@ -131,6 +103,10 @@ export const stripHallucinationsFromString = (text: string): string => {
     return text.replace(DCP_SYSTEM_REMINDER_REGEX, "").replace(DCP_MESSAGE_ID_TAG_REGEX, "")
 }
 
+export const sanitizeVisibleOutput = (text: string): string => {
+    return stripHallucinationsFromString(text).replace(/\n{3,}/g, "\n\n").trimEnd()
+}
+
 export const stripHallucinations = (messages: WithParts[]): void => {
     for (const message of messages) {
         for (const part of message.parts) {