diff --git a/README.md b/README.md
index 1d4e95f..4f667e0 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ Load conductor from the GitHub repository rather than from npm. The GitHub sourc
 ```json
   "dependencies": {
     ...
-    "conductor": "https://github.com/source-academy/conductor.git#0.3.0",
+    "conductor": "https://github.com/source-academy/conductor.git#0.4.0",
      ...
   }, ...
 ```
@@ -72,9 +72,37 @@ Consult [`language-directory` repository](https://github.com/source-academy/lang
 ### Sending messages
 To send messages between the runner and host, use these methods:
 
-- `sendResult(result: string)` — sends evaluation results as a string over the `__result` channel.
+- `sendResult(result: ChannelValue)` — sends evaluation results over the `__result` channel.
 - `sendError(error: ConductorError)` — sends errors over the `__error` channel.
-- `sendOutput(message: string)` — sends standard output/log messages over the `__stdio` channel.
+- `sendOutput(message: ChannelValue)` — sends standard output/log messages over the `__stdio` channel.
+
+A `ChannelValue` carries a mandatory `replString` for display and an optional `payload` for rich rendering:
+
+```ts
+interface ChannelValue {
+    replString: string;        // always displayable as text
+    payload?: ResultPayload;   // optional typed data for rich rendering
+}
+
+interface ResultPayload {
+    type: string;              // discriminant for frontend renderers
+}
+```
+
+For example, an evaluator that produces a numeric result:
+```ts
+sendResult({ replString: "42" });
+```
+
+Or a result with a rich payload that the frontend can render specially:
+```ts
+sendResult({
+    replString: "[Rune]",
+    payload: { type: "rune", rune: runeObject }
+});
+```
+
+If the frontend does not have a renderer for the payload type, it falls back to displaying `replString`.
 
 These methods are available on the relevant runner plugin classes. Call the messaging methods on the plugin instance you receive in your evaluator or plugin code.
 
@@ -156,6 +184,8 @@ The host (i.e., the frontend REPL) formats messages differently depending on the
 - Output (from `__stdio`) appear in orange. Used to send IO messages (e.g. display calls).
 - Results (from `__result`) appear in the default color. Used to display program return results.
 
+The `__result` and `__stdio` channels carry `ChannelValue` objects, which always include a `replString` for text display and may include a typed `payload` for rich rendering (e.g. interactive visualizations, media controls). The `__error` channel carries `ConductorError` objects.
+
 If you are implementing your own `RunnerPlugin` (or similar plugin), you should use the `__result`, `__error`, and `__stdio` channels for results, errors, and output respectively to ensure compatibility with the host and consistent REPL formatting.
 
 
diff --git a/src/conductor/host/BasicHostPlugin.ts b/src/conductor/host/BasicHostPlugin.ts
index 4dd90c8..003a1ec 100644
--- a/src/conductor/host/BasicHostPlugin.ts
+++ b/src/conductor/host/BasicHostPlugin.ts
@@ -3,7 +3,7 @@ import type { ConductorError } from "../../common/errors";
 import { importExternalPlugin } from "../../common/util";
 import { checkIsPluginClass, type PluginClass, makeRpc, type IChannel, type IConduit, type IPlugin } from "../../conduit";
 import { InternalPluginId, InternalChannelName } from "../strings";
-import { type IChunkMessage, type IServiceMessage, RunnerStatus, ServiceMessageType, HelloServiceMessage, AbortServiceMessage, EntryServiceMessage, type Chunk, type IErrorMessage, type IStatusMessage, type IIOMessage } from "../types";
+import { type ChannelValue, type IChunkMessage, type IServiceMessage, RunnerStatus, ServiceMessageType, HelloServiceMessage, AbortServiceMessage, EntryServiceMessage, type Chunk, type IErrorMessage, type IStatusMessage, type IIOMessage } from "../types";
 import type { IHostFileRpc, IHostPlugin, IHostPluginRpc } from "./types";
 
 @checkIsPluginClass
@@ -49,11 +49,11 @@ export abstract class BasicHostPlugin implements IHostPlugin {
         this.__chunkChannel.send({ id: this.__chunkCount++, chunk });
     }
 
-    sendInput(message: string): void {
+    sendInput(message: ChannelValue): void {
         this.__ioChannel.send({ message });
     }
 
-    receiveOutput?(message: string): void;
+    receiveOutput?(message: ChannelValue): void;
 
     receiveError?(message: ConductorError): void;
 
diff --git a/src/conductor/host/types/IHostPlugin.ts b/src/conductor/host/types/IHostPlugin.ts
index 2b2758a..be11335 100644
--- a/src/conductor/host/types/IHostPlugin.ts
+++ b/src/conductor/host/types/IHostPlugin.ts
@@ -1,6 +1,6 @@
 import type { ConductorError } from "../../../common/errors";
 import type { IPlugin, PluginClass } from "../../../conduit";
-import type { Chunk, RunnerStatus } from "../../types";
+import type { ChannelValue, Chunk, RunnerStatus } from "../../types";
 
 export interface IHostPlugin extends IPlugin {
     /**
@@ -39,25 +39,25 @@ export interface IHostPlugin extends IPlugin {
      * Send an input on standard-input.
      * @param input The input to be sent on standard-input.
      */
-    sendInput(input: string): void;
+    sendInput(input: ChannelValue): void;
 
     // /**
     //  * Request for some output on standard-output.
     //  * @returns A promise resolving to the output received.
     //  */
-    // requestOutput(): Promise<string>;
+    // requestOutput(): Promise<ChannelValue>;
 
     // /**
     //  * Try to request for some output on standard-output.
     //  * @returns The output received, or undefined if there is currently no output.
     //  */
-    // tryRequestOutput(): string | undefined;
+    // tryRequestOutput(): ChannelValue | undefined;
 
     /**
      * An event handler called when an output is received.
      * @param message The output received.
      */
-    receiveOutput?(message: string): void;
+    receiveOutput?(message: ChannelValue): void;
 
     // /**
     //  * Request for some output on standard-error.
diff --git a/src/conductor/runner/RunnerPlugin.ts b/src/conductor/runner/RunnerPlugin.ts
index 83f74ab..0011fda 100644
--- a/src/conductor/runner/RunnerPlugin.ts
+++ b/src/conductor/runner/RunnerPlugin.ts
@@ -6,7 +6,7 @@ import { type IConduit, type IChannelQueue, ChannelQueue, makeRpc, checkIsPlugin
 import type { IHostFileRpc, IHostPluginRpc } from "../host";
 import type { IModulePlugin, ModuleClass } from "../module";
 import { InternalChannelName, InternalPluginId } from "../strings";
-import { RunnerStatus, ServiceMessageType, HelloServiceMessage, AbortServiceMessage, type EntryServiceMessage, type Chunk, type IChunkMessage, type IErrorMessage, type IIOMessage, type IResultMessage, type IServiceMessage, type IStatusMessage, } from "../types";
+import { RunnerStatus, ServiceMessageType, HelloServiceMessage, AbortServiceMessage, type EntryServiceMessage, type ChannelValue, type Chunk, type IChunkMessage, type IErrorMessage, type IIOMessage, type IResultMessage, type IServiceMessage, type IStatusMessage, } from "../types";
 import { type EvaluatorClass, type IEvaluator, type IInterfacableEvaluator, type IRunnerPlugin } from "./types";
 
 @checkIsPluginClass
@@ -52,21 +52,21 @@ export class RunnerPlugin implements IRunnerPlugin {
         return (await this.__chunkQueue.receive()).chunk;
     }
 
-    async requestInput(): Promise<string> {
+    async requestInput(): Promise<ChannelValue> {
         const { message } = await this.__ioQueue.receive();
         return message;
     }
 
-    tryRequestInput(): string | undefined {
+    tryRequestInput(): ChannelValue | undefined {
         const out = this.__ioQueue.tryReceive();
         return out?.message;
     }
 
-    sendOutput(message: string): void {
+    sendOutput(message: ChannelValue): void {
         this.__ioQueue.send({ message });
     }
 
-    sendResult(result: any): void {
+    sendResult(result: ChannelValue): void {
         this.__resultChannel.send({ result });
     }
 
diff --git a/src/conductor/runner/types/IRunnerPlugin.ts b/src/conductor/runner/types/IRunnerPlugin.ts
index dd3a570..b1545d4 100644
--- a/src/conductor/runner/types/IRunnerPlugin.ts
+++ b/src/conductor/runner/types/IRunnerPlugin.ts
@@ -1,7 +1,7 @@
 import type { ConductorError } from "../../../common/errors";
 import type { IPlugin, PluginClass } from "../../../conduit";
 import type { IModulePlugin, ModuleClass } from "../../module";
-import type { Chunk, RunnerStatus } from "../../types";
+import type { ChannelValue, Chunk, RunnerStatus } from "../../types";
 
 export interface IRunnerPlugin extends IPlugin {
     /**
@@ -21,25 +21,25 @@ export interface IRunnerPlugin extends IPlugin {
      * Request for some input on standard-input.
      * @returns A promise resolving to the input received.
      */
-    requestInput(): Promise<string>;
+    requestInput(): Promise<ChannelValue>;
 
     /**
      * Try to request for some input on standard-input.
      * @returns The input received, or undefined if there is currently no input.
      */
-    tryRequestInput(): string | undefined;
+    tryRequestInput(): ChannelValue | undefined;
 
     /**
      * Sends a message on standard-output.
      * @param message The output message to send.
      */
-    sendOutput(message: string): void;
+    sendOutput(message: ChannelValue): void;
 
     /**
      * Sends an evaluation result.
      * @param result The result to send.
      */
-    sendResult(result: any): void;
+    sendResult(result: ChannelValue): void;
 
     /**
      * Sends an error.
diff --git a/src/conductor/types/ChannelValue.ts b/src/conductor/types/ChannelValue.ts
new file mode 100644
index 0000000..f95c4f4
--- /dev/null
+++ b/src/conductor/types/ChannelValue.ts
@@ -0,0 +1,11 @@
+import type { ResultPayload } from "./ResultPayload";
+
+/**
+ * A serializable value carried on user-facing channels
+ * (__result, __stdio). Always includes a string representation;
+ * optionally includes a typed payload for rich rendering.
+ */
+export interface ChannelValue {
+    replString: string;
+    payload?: ResultPayload;
+}
diff --git a/src/conductor/types/IIOMessage.ts b/src/conductor/types/IIOMessage.ts
index d09b739..fbe6c39 100644
--- a/src/conductor/types/IIOMessage.ts
+++ b/src/conductor/types/IIOMessage.ts
@@ -1,4 +1,5 @@
+import type { ChannelValue } from "./ChannelValue";
+
 export interface IIOMessage {
-    // stream: number;
-    message: string;
+    message: ChannelValue;
 }
diff --git a/src/conductor/types/IResultMessage.ts b/src/conductor/types/IResultMessage.ts
index 78af101..18c1dcd 100644
--- a/src/conductor/types/IResultMessage.ts
+++ b/src/conductor/types/IResultMessage.ts
@@ -1,3 +1,5 @@
+import type { ChannelValue } from "./ChannelValue";
+
 export interface IResultMessage {
-    result: any;
+    result: ChannelValue;
 }
diff --git a/src/conductor/types/ResultPayload.ts b/src/conductor/types/ResultPayload.ts
new file mode 100644
index 0000000..b1dfba3
--- /dev/null
+++ b/src/conductor/types/ResultPayload.ts
@@ -0,0 +1,8 @@
+/**
+ * Base interface for rich result payloads.
+ * The conductor treats this opaquely — concrete payload
+ * types are defined downstream (e.g. in modules).
+ */
+export interface ResultPayload {
+    type: string;
+}
diff --git a/src/conductor/types/index.ts b/src/conductor/types/index.ts
index 516902d..4e05ed1 100644
--- a/src/conductor/types/index.ts
+++ b/src/conductor/types/index.ts
@@ -1,11 +1,13 @@
 export * from "./moduleInterface";
 export * from "./serviceMessages";
 
+export type { ChannelValue } from "./ChannelValue";
 export type { Chunk } from "./Chunk";
 export type { IChunkMessage } from "./IChunkMessage";
 export type { IErrorMessage } from "./IErrorMessage";
 export type { IIOMessage } from "./IIOMessage";
 export type { IResultMessage } from "./IResultMessage";
+export type { ResultPayload } from "./ResultPayload";
 export type { IServiceMessage } from "./IServiceMessage";
 export type { IStatusMessage } from "./IStatusMessage";
 export { RunnerStatus } from "./RunnerStatus";