diff --git a/packages/core/src/agent/runner.ts b/packages/core/src/agent/runner.ts
index 3e7c2f22..92ce68dd 100644
--- a/packages/core/src/agent/runner.ts
+++ b/packages/core/src/agent/runner.ts
@@ -1192,6 +1192,7 @@ export class Agent {
       tools: toolNames,
       skillsPrompt,
       runtime,
+      channels: this.toolsOptions.channels,
     });
   }
 }
diff --git a/packages/core/src/agent/system-prompt/builder.ts b/packages/core/src/agent/system-prompt/builder.ts
index 82d01860..f7120d72 100644
--- a/packages/core/src/agent/system-prompt/builder.ts
+++ b/packages/core/src/agent/system-prompt/builder.ts
@@ -10,6 +10,7 @@ import type {
   SystemPromptReport,
 } from "./types.js";
 import {
+  buildChannelsSection,
   buildHeartbeatSection,
   buildConditionalToolSections,
   buildExtraPromptSection,
@@ -51,6 +52,7 @@ export function buildSystemPromptWithReport(options: SystemPromptOptions): {
     skillsPrompt,
     runtime,
     subagent,
+    channels,
     extraSystemPrompt,
     includeSafety = true,
   } = options;
@@ -70,6 +72,7 @@ export function buildSystemPromptWithReport(options: SystemPromptOptions): {
     { name: "runtime", lines: buildRuntimeSection(runtime, mode) },
     { name: "time-awareness", lines: buildTimeAwarenessSection(tools, mode) },
     { name: "profile-dir", lines: buildProfileDirSection(profileDir, mode) },
+    { name: "channels", lines: buildChannelsSection(channels, mode) },
     { name: "subagent", lines: buildSubagentSection(subagent, mode) },
     { name: "extra", lines: buildExtraPromptSection(extraSystemPrompt, mode) },
   ];
diff --git a/packages/core/src/agent/system-prompt/index.ts b/packages/core/src/agent/system-prompt/index.ts
index 6c1a9ffe..5944eb39 100644
--- a/packages/core/src/agent/system-prompt/index.ts
+++ b/packages/core/src/agent/system-prompt/index.ts
@@ -8,6 +8,7 @@ export { formatPromptReport } from "./report.js";
 export { SAFETY_CONSTITUTION } from "./constitution.js";
 
 export type {
+  ChannelInfo,
   ProfileContent,
   PromptSection,
   RuntimeInfo,
diff --git a/packages/core/src/agent/system-prompt/sections.ts b/packages/core/src/agent/system-prompt/sections.ts
index 99573cbd..60caee95 100644
--- a/packages/core/src/agent/system-prompt/sections.ts
+++ b/packages/core/src/agent/system-prompt/sections.ts
@@ -8,6 +8,7 @@ import { SAFETY_CONSTITUTION } from "./constitution.js";
 import { formatRuntimeLine } from "./runtime-info.js";
 import { resolveHeartbeatPrompt } from "../../heartbeat/heartbeat-text.js";
 import type {
+  ChannelInfo,
   ProfileContent,
   RuntimeInfo,
   SubagentContext,
@@ -461,6 +462,40 @@ export function buildSubagentSection(
   return lines;
 }
 
+/**
+ * Connected channels section — tells the agent which messaging channels are active
+ * and what capabilities they have (e.g. send files). Full mode only.
+ */
+export function buildChannelsSection(
+  channels: ChannelInfo[] | undefined,
+  mode: SystemPromptMode,
+): string[] {
+  if (mode !== "full" || !channels || channels.length === 0) return [];
+
+  const lines: string[] = ["## Connected Channels", ""];
+
+  for (const ch of channels) {
+    lines.push(`- **${ch.name}**`);
+    if (ch.canSendMedia) {
+      lines.push(
+        "  Capabilities: receive text/voice/image/video/document, send text, send files (photo, document, video, audio)",
+      );
+      lines.push("  Use the `send_file` tool to send files to channel users.");
+    } else {
+      lines.push("  Capabilities: receive text, send text");
+    }
+  }
+
+  lines.push(
+    "",
+    "Messages from channels are prefixed with `[ChannelName · private]` or `[ChannelName · group]`.",
+    "When responding to channel messages, adapt your formatting for messaging platforms (shorter paragraphs, no complex markdown).",
+    "",
+  );
+
+  return lines;
+}
+
 /**
  * Extra system prompt — appended at the end if provided.
  */
diff --git a/packages/core/src/agent/system-prompt/types.ts b/packages/core/src/agent/system-prompt/types.ts
index cf1cc1ba..0741a80e 100644
--- a/packages/core/src/agent/system-prompt/types.ts
+++ b/packages/core/src/agent/system-prompt/types.ts
@@ -37,6 +37,14 @@ export interface RuntimeInfo {
   cwd?: string | undefined;
 }
 
+/** Describes a connected messaging channel and its capabilities */
+export interface ChannelInfo {
+  /** Human-readable channel name (e.g. "Telegram") */
+  name: string;
+  /** Whether the channel supports outbound media via send_file */
+  canSendMedia: boolean;
+}
+
 /** Subagent context for minimal/none modes */
 export interface SubagentContext {
   /** Parent session that spawned this subagent */
@@ -77,6 +85,8 @@ export interface SystemPromptOptions {
   subagent?: SubagentContext | undefined;
   /** Workspace directory path (for agent working directory info) */
   workspaceDir?: string | undefined;
+  /** Connected messaging channels (for channel awareness section) */
+  channels?: ChannelInfo[] | undefined;
   /** Extra system prompt to append */
   extraSystemPrompt?: string | undefined;
   /** Whether to include the safety constitution (default: true) */