diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index a7c2251db..e5cd1676a 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -17,6 +17,8 @@
 
 ### Added
 
+- Exposed `PI_SESSION_ID`, `PI_SESSION_FILE`, `PI_PROVIDER`, `PI_MODEL`, and `PI_REASONING_LEVEL` to commands run by built-in and factory-created bash tools.
+- Exposed the `outputPad` setting to custom message renderers.
 - Added inherited `Tool.constrainedSampling` with strict JSON Schema (`prefer`/`require`) and OpenAI Lark/regex grammar variants across OpenAI, Anthropic, Amazon Bedrock, Google Gemini, and Mistral. See [Constrained Sampling for Tools](../ai/README.md#constrained-sampling-for-tools).
 - Added inherited `supportsGrammarTools` and `supportsStrictTools` compatibility flags, expanded `supportsStrictMode` coverage, and generated model capability metadata to gate constrained sampling.
 - Added inherited Kimi Code subscription OAuth login for the Kimi For Coding provider, including device authorization and automatic token refresh ([#6935](https://github.com/earendil-works/pi/pull/6935) by [@zaycruz](https://github.com/zaycruz)).
diff --git a/packages/coding-agent/docs/extensions.md b/packages/coding-agent/docs/extensions.md
index 1622ca6fa..aeb5e866a 100644
--- a/packages/coding-agent/docs/extensions.md
+++ b/packages/coding-agent/docs/extensions.md
@@ -2791,7 +2791,7 @@ Register a custom renderer for messages with your `customType`. Use message rend
 import { Text } from "@earendil-works/pi-tui";
 
 pi.registerMessageRenderer("my-extension", (message, options, theme) => {
-  const { expanded } = options;
+  const { expanded, outputPad } = options;
   let text = theme.fg("accent", `[${message.customType}] `);
   text += message.content;
 
@@ -2799,7 +2799,7 @@ pi.registerMessageRenderer("my-extension", (message, options, theme) => {
     text += "\n" + theme.fg("dim", JSON.stringify(message.details, null, 2));
   }
 
-  return new Text(text, 0, 0);
+  return new Text(text, outputPad, 0);
 });
 ```
 
diff --git a/packages/coding-agent/examples/extensions/message-renderer.ts b/packages/coding-agent/examples/extensions/message-renderer.ts
index 9183d1ec6..953941ee2 100644
--- a/packages/coding-agent/examples/extensions/message-renderer.ts
+++ b/packages/coding-agent/examples/extensions/message-renderer.ts
@@ -12,7 +12,7 @@ import { Box, Text } from "@earendil-works/pi-tui";
 
 export default function (pi: ExtensionAPI) {
 	// Register custom renderer for "status-update" messages
-	pi.registerMessageRenderer("status-update", (message, { expanded }, theme) => {
+	pi.registerMessageRenderer("status-update", (message, { expanded, outputPad }, theme) => {
 		const details = message.details as { level: string; timestamp: number } | undefined;
 		const level = details?.level ?? "info";
 
@@ -29,7 +29,7 @@ export default function (pi: ExtensionAPI) {
 		}
 
 		// Use Box with customMessageBg for consistent styling
-		const box = new Box(1, 1, (t) => theme.bg("customMessageBg", t));
+		const box = new Box(outputPad, 1, (t) => theme.bg("customMessageBg", t));
 		box.addChild(new Text(text, 0, 0));
 		return box;
 	});
diff --git a/packages/coding-agent/src/core/extensions/types.ts b/packages/coding-agent/src/core/extensions/types.ts
index 22b386ba8..c8989a59c 100644
--- a/packages/coding-agent/src/core/extensions/types.ts
+++ b/packages/coding-agent/src/core/extensions/types.ts
@@ -1129,6 +1129,8 @@ export interface SessionBeforeTreeResult {
 
 export interface MessageRenderOptions {
 	expanded: boolean;
+	/** Horizontal padding configured by the outputPad setting. */
+	outputPad: number;
 }
 
 export interface EntryRenderOptions {
diff --git a/packages/coding-agent/src/modes/interactive/components/custom-message.ts b/packages/coding-agent/src/modes/interactive/components/custom-message.ts
index a8fffc6f3..b5ee92658 100644
--- a/packages/coding-agent/src/modes/interactive/components/custom-message.ts
+++ b/packages/coding-agent/src/modes/interactive/components/custom-message.ts
@@ -16,16 +16,19 @@ export class CustomMessageComponent extends Container {
 	private customComponent?: Component;
 	private markdownTheme: MarkdownTheme;
 	private _expanded = false;
+	private outputPad: number;
 
 	constructor(
 		message: CustomMessage<unknown>,
 		customRenderer?: MessageRenderer,
 		markdownTheme: MarkdownTheme = getMarkdownTheme(),
+		outputPad = 1,
 	) {
 		super();
 		this.message = message;
 		this.customRenderer = customRenderer;
 		this.markdownTheme = markdownTheme;
+		this.outputPad = outputPad;
 
 		this.addChild(new Spacer(1));
 
@@ -42,6 +45,13 @@ export class CustomMessageComponent extends Container {
 		}
 	}
 
+	setOutputPad(outputPad: number): void {
+		if (this.outputPad !== outputPad) {
+			this.outputPad = outputPad;
+			this.rebuild();
+		}
+	}
+
 	override invalidate(): void {
 		super.invalidate();
 		this.rebuild();
@@ -58,7 +68,11 @@ export class CustomMessageComponent extends Container {
 		// Try custom renderer first - it handles its own styling
 		if (this.customRenderer) {
 			try {
-				const component = this.customRenderer(this.message, { expanded: this._expanded }, theme);
+				const component = this.customRenderer(
+					this.message,
+					{ expanded: this._expanded, outputPad: this.outputPad },
+					theme,
+				);
 				if (component) {
 					// Custom renderer provides its own styled component
 					this.customComponent = component;
diff --git a/packages/coding-agent/src/modes/interactive/interactive-mode.ts b/packages/coding-agent/src/modes/interactive/interactive-mode.ts
index de2872dbd..30cd984f7 100644
--- a/packages/coding-agent/src/modes/interactive/interactive-mode.ts
+++ b/packages/coding-agent/src/modes/interactive/interactive-mode.ts
@@ -3242,7 +3242,12 @@ export class InteractiveMode {
 			case "custom": {
 				if (message.display) {
 					const renderer = this.session.extensionRunner.getMessageRenderer(message.customType);
-					const component = new CustomMessageComponent(message, renderer, this.getMarkdownThemeWithSettings());
+					const component = new CustomMessageComponent(
+						message,
+						renderer,
+						this.getMarkdownThemeWithSettings(),
+						this.outputPad,
+					);
 					component.setExpanded(this.toolOutputExpanded);
 					this.chatContainer.addChild(component);
 				}
@@ -4257,7 +4262,11 @@ export class InteractiveMode {
 						this.outputPad = padding;
 						if (this.streamingComponent || this.session.isStreaming) {
 							for (const child of this.chatContainer.children) {
-								if (child instanceof AssistantMessageComponent || child instanceof UserMessageComponent) {
+								if (
+									child instanceof AssistantMessageComponent ||
+									child instanceof CustomMessageComponent ||
+									child instanceof UserMessageComponent
+								) {
 									child.setOutputPad(padding);
 								}
 							}
diff --git a/packages/coding-agent/test/custom-message.test.ts b/packages/coding-agent/test/custom-message.test.ts
new file mode 100644
index 000000000..cdc598010
--- /dev/null
+++ b/packages/coding-agent/test/custom-message.test.ts
@@ -0,0 +1,44 @@
+import { Text } from "@earendil-works/pi-tui";
+import { describe, expect, test } from "vitest";
+import type { MessageRenderer, MessageRenderOptions } from "../src/core/extensions/types.ts";
+import type { CustomMessage } from "../src/core/messages.ts";
+import { CustomMessageComponent } from "../src/modes/interactive/components/custom-message.ts";
+import { initTheme } from "../src/modes/interactive/theme/theme.ts";
+import { stripAnsi } from "../src/utils/ansi.ts";
+
+describe("CustomMessageComponent", () => {
+	test("provides output padding to custom renderers and updates it", () => {
+		initTheme("dark");
+		const optionsSeen: MessageRenderOptions[] = [];
+		const renderer: MessageRenderer = (_message, options) => {
+			optionsSeen.push(options);
+			return new Text("custom", options.outputPad, 0);
+		};
+		const message: CustomMessage = {
+			role: "custom",
+			customType: "test",
+			content: "custom",
+			display: true,
+			timestamp: Date.now(),
+		};
+		const component = new CustomMessageComponent(message, renderer, undefined, 1);
+
+		expect(optionsSeen).toEqual([{ expanded: false, outputPad: 1 }]);
+		expect(
+			component
+				.render(40)
+				.map(stripAnsi)
+				.some((line) => line.startsWith(" custom")),
+		).toBe(true);
+
+		component.setOutputPad(0);
+
+		expect(optionsSeen.at(-1)).toEqual({ expanded: false, outputPad: 0 });
+		expect(
+			component
+				.render(40)
+				.map(stripAnsi)
+				.some((line) => line.startsWith("custom")),
+		).toBe(true);
+	});
+});