diff --git a/src/auto-reply/reply/history.test.ts b/src/auto-reply/reply/history.test.ts
index 9727d2d3c..c249d6b29 100644
--- a/src/auto-reply/reply/history.test.ts
+++ b/src/auto-reply/reply/history.test.ts
@@ -3,6 +3,7 @@ import {
   appendHistoryEntry,
   buildHistoryContext,
   buildHistoryContextFromEntries,
+  buildHistoryContextFromMap,
   HISTORY_CONTEXT_MARKER,
 } from "./history.js";
 import { CURRENT_MESSAGE_MARKER } from "./mentions.js";
@@ -60,4 +61,31 @@ describe("history helpers", () => {
       "three",
     ]);
   });
+
+  it("builds context from map and appends entry", () => {
+    const historyMap = new Map<string, { sender: string; body: string }[]>();
+    historyMap.set("room", [
+      { sender: "A", body: "one" },
+      { sender: "B", body: "two" },
+    ]);
+
+    const result = buildHistoryContextFromMap({
+      historyMap,
+      historyKey: "room",
+      limit: 3,
+      entry: { sender: "C", body: "three" },
+      currentMessage: "current",
+      formatEntry: (entry) => `${entry.sender}: ${entry.body}`,
+    });
+
+    expect(historyMap.get("room")?.map((entry) => entry.body)).toEqual([
+      "one",
+      "two",
+      "three",
+    ]);
+    expect(result).toContain(HISTORY_CONTEXT_MARKER);
+    expect(result).toContain("A: one");
+    expect(result).toContain("B: two");
+    expect(result).not.toContain("C: three");
+  });
 });
diff --git a/src/auto-reply/reply/history.ts b/src/auto-reply/reply/history.ts
index 92b740946..2e30c1d47 100644
--- a/src/auto-reply/reply/history.ts
+++ b/src/auto-reply/reply/history.ts
@@ -43,6 +43,41 @@ export function appendHistoryEntry(params: {
   return history;
 }
 
+export function buildHistoryContextFromMap(params: {
+  historyMap: Map<string, HistoryEntry[]>;
+  historyKey: string;
+  limit: number;
+  entry?: HistoryEntry;
+  currentMessage: string;
+  formatEntry: (entry: HistoryEntry) => string;
+  lineBreak?: string;
+  excludeLast?: boolean;
+}): string {
+  if (params.limit <= 0) return params.currentMessage;
+  const entries = params.entry
+    ? appendHistoryEntry({
+        historyMap: params.historyMap,
+        historyKey: params.historyKey,
+        entry: params.entry,
+        limit: params.limit,
+      })
+    : (params.historyMap.get(params.historyKey) ?? []);
+  return buildHistoryContextFromEntries({
+    entries,
+    currentMessage: params.currentMessage,
+    formatEntry: params.formatEntry,
+    lineBreak: params.lineBreak,
+    excludeLast: params.excludeLast,
+  });
+}
+
+export function clearHistoryEntries(params: {
+  historyMap: Map<string, HistoryEntry[]>;
+  historyKey: string;
+}): void {
+  params.historyMap.set(params.historyKey, []);
+}
+
 export function buildHistoryContextFromEntries(params: {
   entries: HistoryEntry[];
   currentMessage: string;
diff --git a/src/discord/monitor.ts b/src/discord/monitor.ts
index d9ce5c971..11bfef571 100644
--- a/src/discord/monitor.ts
+++ b/src/discord/monitor.ts
@@ -35,8 +35,8 @@ import {
 } from "../auto-reply/envelope.js";
 import { dispatchReplyFromConfig } from "../auto-reply/reply/dispatch-from-config.js";
 import {
-  appendHistoryEntry,
-  buildHistoryContextFromEntries,
+  buildHistoryContextFromMap,
+  clearHistoryEntries,
   type HistoryEntry,
 } from "../auto-reply/reply/history.js";
 import {
@@ -887,23 +887,19 @@ export function createDiscordMessageHandler(params: {
       const textForHistory = resolveDiscordMessageText(message, {
         includeForwarded: true,
       });
-      if (isGuildMessage && historyLimit > 0 && textForHistory) {
-        appendHistoryEntry({
-          historyMap: guildHistories,
-          historyKey: message.channelId,
-          limit: historyLimit,
-          entry: {
-            sender:
-              data.member?.nickname ??
-              author.globalName ??
-              author.username ??
-              author.id,
-            body: textForHistory,
-            timestamp: resolveTimestampMs(message.timestamp),
-            messageId: message.id,
-          },
-        });
-      }
+      const historyEntry =
+        isGuildMessage && historyLimit > 0 && textForHistory
+          ? {
+              sender:
+                data.member?.nickname ??
+                author.globalName ??
+                author.username ??
+                author.id,
+              body: textForHistory,
+              timestamp: resolveTimestampMs(message.timestamp),
+              messageId: message.id,
+            }
+          : undefined;
 
       const shouldRequireMention =
         channelConfig?.requireMention ?? guildInfo?.requireMention ?? true;
@@ -1049,10 +1045,11 @@ export function createDiscordMessageHandler(params: {
       });
       let shouldClearHistory = false;
       if (!isDirectMessage) {
-        const history =
-          historyLimit > 0 ? (guildHistories.get(message.channelId) ?? []) : [];
-        combinedBody = buildHistoryContextFromEntries({
-          entries: history,
+        combinedBody = buildHistoryContextFromMap({
+          historyMap: guildHistories,
+          historyKey: message.channelId,
+          limit: historyLimit,
+          entry: historyEntry,
           currentMessage: combinedBody,
           formatEntry: (entry) =>
             formatAgentEnvelope({
@@ -1227,7 +1224,10 @@ export function createDiscordMessageHandler(params: {
           historyLimit > 0 &&
           didSendReply
         ) {
-          guildHistories.set(message.channelId, []);
+          clearHistoryEntries({
+            historyMap: guildHistories,
+            historyKey: message.channelId,
+          });
         }
         return;
       }
@@ -1262,7 +1262,10 @@ export function createDiscordMessageHandler(params: {
         historyLimit > 0 &&
         didSendReply
       ) {
-        guildHistories.set(message.channelId, []);
+        clearHistoryEntries({
+          historyMap: guildHistories,
+          historyKey: message.channelId,
+        });
       }
     } catch (err) {
       runtime.error?.(danger(`handler failed: ${String(err)}`));
diff --git a/src/imessage/monitor.ts b/src/imessage/monitor.ts
index 2a544a098..be8dcb5e9 100644
--- a/src/imessage/monitor.ts
+++ b/src/imessage/monitor.ts
@@ -7,8 +7,8 @@ import { hasControlCommand } from "../auto-reply/command-detection.js";
 import { formatAgentEnvelope } from "../auto-reply/envelope.js";
 import { dispatchReplyFromConfig } from "../auto-reply/reply/dispatch-from-config.js";
 import {
-  appendHistoryEntry,
-  buildHistoryContextFromEntries,
+  buildHistoryContextFromMap,
+  clearHistoryEntries,
   DEFAULT_GROUP_HISTORY_LIMIT,
   type HistoryEntry,
 } from "../auto-reply/reply/history.js";
@@ -409,7 +409,7 @@ export async function monitorIMessageProvider(
       ? String(chatId ?? chatGuid ?? chatIdentifier ?? "unknown")
       : undefined;
     if (isGroup && historyKey && historyLimit > 0) {
-      appendHistoryEntry({
+      combinedBody = buildHistoryContextFromMap({
         historyMap: groupHistories,
         historyKey,
         limit: historyLimit,
@@ -419,10 +419,6 @@ export async function monitorIMessageProvider(
           timestamp: createdAt,
           messageId: message.id ? String(message.id) : undefined,
         },
-      });
-      const history = groupHistories.get(historyKey) ?? [];
-      combinedBody = buildHistoryContextFromEntries({
-        entries: history,
         currentMessage: combinedBody,
         formatEntry: (entry) =>
           formatAgentEnvelope({
@@ -527,12 +523,12 @@ export async function monitorIMessageProvider(
     });
     if (!queuedFinal) {
       if (isGroup && historyKey && historyLimit > 0 && didSendReply) {
-        groupHistories.set(historyKey, []);
+        clearHistoryEntries({ historyMap: groupHistories, historyKey });
       }
       return;
     }
     if (isGroup && historyKey && historyLimit > 0 && didSendReply) {
-      groupHistories.set(historyKey, []);
+      clearHistoryEntries({ historyMap: groupHistories, historyKey });
     }
   };
 
diff --git a/src/msteams/monitor-handler.ts b/src/msteams/monitor-handler.ts
index 15349579d..ced3ae986 100644
--- a/src/msteams/monitor-handler.ts
+++ b/src/msteams/monitor-handler.ts
@@ -1,8 +1,8 @@
 import { formatAgentEnvelope } from "../auto-reply/envelope.js";
 import { dispatchReplyFromConfig } from "../auto-reply/reply/dispatch-from-config.js";
 import {
-  appendHistoryEntry,
-  buildHistoryContextFromEntries,
+  buildHistoryContextFromMap,
+  clearHistoryEntries,
   DEFAULT_GROUP_HISTORY_LIMIT,
   type HistoryEntry,
 } from "../auto-reply/reply/history.js";
@@ -432,7 +432,7 @@ function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
     const isRoomish = !isDirectMessage;
     const historyKey = isRoomish ? conversationId : undefined;
     if (isRoomish && historyKey && historyLimit > 0) {
-      appendHistoryEntry({
+      combinedBody = buildHistoryContextFromMap({
         historyMap: conversationHistories,
         historyKey,
         limit: historyLimit,
@@ -442,10 +442,6 @@ function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
           timestamp: timestamp?.getTime(),
           messageId: activity.id ?? undefined,
         },
-      });
-      const history = conversationHistories.get(historyKey) ?? [];
-      combinedBody = buildHistoryContextFromEntries({
-        entries: history,
         currentMessage: combinedBody,
         formatEntry: (entry) =>
           formatAgentEnvelope({
@@ -520,7 +516,10 @@ function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
       const didSendReply = counts.final + counts.tool + counts.block > 0;
       if (!queuedFinal) {
         if (isRoomish && historyKey && historyLimit > 0 && didSendReply) {
-          conversationHistories.set(historyKey, []);
+          clearHistoryEntries({
+            historyMap: conversationHistories,
+            historyKey,
+          });
         }
         return;
       }
@@ -531,7 +530,10 @@ function createMSTeamsMessageHandler(deps: MSTeamsMessageHandlerDeps) {
         );
       }
       if (isRoomish && historyKey && historyLimit > 0 && didSendReply) {
-        conversationHistories.set(historyKey, []);
+        clearHistoryEntries({
+          historyMap: conversationHistories,
+          historyKey,
+        });
       }
     } catch (err) {
       log.error("dispatch failed", { error: String(err) });
diff --git a/src/signal/monitor.ts b/src/signal/monitor.ts
index 112834ec0..bed4a0cde 100644
--- a/src/signal/monitor.ts
+++ b/src/signal/monitor.ts
@@ -6,8 +6,8 @@ import { chunkText, resolveTextChunkLimit } from "../auto-reply/chunk.js";
 import { formatAgentEnvelope } from "../auto-reply/envelope.js";
 import { dispatchReplyFromConfig } from "../auto-reply/reply/dispatch-from-config.js";
 import {
-  appendHistoryEntry,
-  buildHistoryContextFromEntries,
+  buildHistoryContextFromMap,
+  clearHistoryEntries,
   DEFAULT_GROUP_HISTORY_LIMIT,
   type HistoryEntry,
 } from "../auto-reply/reply/history.js";
@@ -635,7 +635,7 @@ export async function monitorSignalProvider(
       let combinedBody = body;
       const historyKey = isGroup ? String(groupId ?? "unknown") : undefined;
       if (isGroup && historyKey && historyLimit > 0) {
-        appendHistoryEntry({
+        combinedBody = buildHistoryContextFromMap({
           historyMap: groupHistories,
           historyKey,
           limit: historyLimit,
@@ -648,10 +648,6 @@ export async function monitorSignalProvider(
                 ? String(envelope.timestamp)
                 : undefined,
           },
-        });
-        const history = groupHistories.get(historyKey) ?? [];
-        combinedBody = buildHistoryContextFromEntries({
-          entries: history,
           currentMessage: combinedBody,
           formatEntry: (entry) =>
             formatAgentEnvelope({
@@ -763,12 +759,12 @@ export async function monitorSignalProvider(
       });
       if (!queuedFinal) {
         if (isGroup && historyKey && historyLimit > 0 && didSendReply) {
-          groupHistories.set(historyKey, []);
+          clearHistoryEntries({ historyMap: groupHistories, historyKey });
         }
         return;
       }
       if (isGroup && historyKey && historyLimit > 0 && didSendReply) {
-        groupHistories.set(historyKey, []);
+        clearHistoryEntries({ historyMap: groupHistories, historyKey });
       }
     };
 
diff --git a/src/slack/monitor.ts b/src/slack/monitor.ts
index da4c09acb..44ddd66ad 100644
--- a/src/slack/monitor.ts
+++ b/src/slack/monitor.ts
@@ -25,8 +25,8 @@ import {
 } from "../auto-reply/envelope.js";
 import { dispatchReplyFromConfig } from "../auto-reply/reply/dispatch-from-config.js";
 import {
-  appendHistoryEntry,
-  buildHistoryContextFromEntries,
+  buildHistoryContextFromMap,
+  clearHistoryEntries,
   DEFAULT_GROUP_HISTORY_LIMIT,
   type HistoryEntry,
 } from "../auto-reply/reply/history.js";
@@ -969,21 +969,17 @@ export async function monitorSlackProvider(opts: MonitorSlackOpts = {}) {
     const roomLabel = channelName ? `#${channelName}` : `#${message.channel}`;
     const isRoomish = isRoom || isGroupDm;
     const historyKey = message.channel;
-    if (isRoomish && historyLimit > 0) {
-      appendHistoryEntry({
-        historyMap: channelHistories,
-        historyKey,
-        limit: historyLimit,
-        entry: {
-          sender: senderName,
-          body: rawBody,
-          timestamp: message.ts
-            ? Math.round(Number(message.ts) * 1000)
-            : undefined,
-          messageId: message.ts,
-        },
-      });
-    }
+    const historyEntry =
+      isRoomish && historyLimit > 0
+        ? {
+            sender: senderName,
+            body: rawBody,
+            timestamp: message.ts
+              ? Math.round(Number(message.ts) * 1000)
+              : undefined,
+            messageId: message.ts,
+          }
+        : undefined;
 
     const preview = rawBody.replace(/\s+/g, " ").slice(0, 160);
     const inboundLabel = isDirectMessage
@@ -1021,9 +1017,11 @@ export async function monitorSlackProvider(opts: MonitorSlackOpts = {}) {
 
     let combinedBody = body;
     if (isRoomish && historyLimit > 0) {
-      const history = channelHistories.get(historyKey) ?? [];
-      combinedBody = buildHistoryContextFromEntries({
-        entries: history,
+      combinedBody = buildHistoryContextFromMap({
+        historyMap: channelHistories,
+        historyKey,
+        limit: historyLimit,
+        entry: historyEntry,
         currentMessage: combinedBody,
         formatEntry: (entry) =>
           formatAgentEnvelope({
@@ -1220,7 +1218,7 @@ export async function monitorSlackProvider(opts: MonitorSlackOpts = {}) {
     }
     if (!queuedFinal) {
       if (isRoomish && historyLimit > 0 && didSendReply) {
-        channelHistories.set(historyKey, []);
+        clearHistoryEntries({ historyMap: channelHistories, historyKey });
       }
       return;
     }
@@ -1245,7 +1243,7 @@ export async function monitorSlackProvider(opts: MonitorSlackOpts = {}) {
       });
     }
     if (isRoomish && historyLimit > 0 && didSendReply) {
-      channelHistories.set(historyKey, []);
+      clearHistoryEntries({ historyMap: channelHistories, historyKey });
     }
   };
 
diff --git a/src/telegram/bot.ts b/src/telegram/bot.ts
index d36fd3b2e..9eadd1469 100644
--- a/src/telegram/bot.ts
+++ b/src/telegram/bot.ts
@@ -21,8 +21,8 @@ import {
 import { formatAgentEnvelope } from "../auto-reply/envelope.js";
 import { resolveTelegramDraftStreamingChunking } from "../auto-reply/reply/block-streaming.js";
 import {
-  appendHistoryEntry,
-  buildHistoryContextFromEntries,
+  buildHistoryContextFromMap,
+  clearHistoryEntries,
   DEFAULT_GROUP_HISTORY_LIMIT,
   type HistoryEntry,
 } from "../auto-reply/reply/history.js";
@@ -671,7 +671,7 @@ export function createTelegramBot(opts: TelegramBotOptions) {
       ? buildTelegramGroupPeerId(chatId, messageThreadId)
       : undefined;
     if (isGroup && historyKey && historyLimit > 0) {
-      appendHistoryEntry({
+      combinedBody = buildHistoryContextFromMap({
         historyMap: groupHistories,
         historyKey,
         limit: historyLimit,
@@ -684,10 +684,6 @@ export function createTelegramBot(opts: TelegramBotOptions) {
               ? String(msg.message_id)
               : undefined,
         },
-      });
-      const history = groupHistories.get(historyKey) ?? [];
-      combinedBody = buildHistoryContextFromEntries({
-        entries: history,
         currentMessage: combinedBody,
         formatEntry: (entry) =>
           formatAgentEnvelope({
@@ -907,7 +903,7 @@ export function createTelegramBot(opts: TelegramBotOptions) {
     draftStream?.stop();
     if (!queuedFinal) {
       if (isGroup && historyKey && historyLimit > 0 && didSendReply) {
-        groupHistories.set(historyKey, []);
+        clearHistoryEntries({ historyMap: groupHistories, historyKey });
       }
       return;
     }
@@ -927,7 +923,7 @@ export function createTelegramBot(opts: TelegramBotOptions) {
       });
     }
     if (isGroup && historyKey && historyLimit > 0 && didSendReply) {
-      groupHistories.set(historyKey, []);
+      clearHistoryEntries({ historyMap: groupHistories, historyKey });
     }
   };