diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 3e05f500c..ddd175ba8 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -431,6 +431,7 @@
 
 - Integrated testing guidance directly into the main system prompt for improved workflow cohesion
 - Moved testing guidance into the main system prompt and removed the bundled Tester subagent.
+- Fixed a crash when a plugin/custom tool renderer returns a component that throws during its later `render()` pass (e.g. `TypeError: th.bold is not a function` from a plugin that styles its header off an object without a `bold` method). `ToolExecutionComponent` now wraps every renderer-returned call/result component so a throwing `render()` degrades to the safe fallback (tool label or raw result text) instead of taking down the transcript ([#4978](https://github.com/can1357/oh-my-pi/issues/4978)).
 
 ## [16.3.14] - 2026-07-09
 
diff --git a/packages/coding-agent/src/modes/components/tool-execution.test.ts b/packages/coding-agent/src/modes/components/tool-execution.test.ts
new file mode 100644
index 000000000..1408f80d7
--- /dev/null
+++ b/packages/coding-agent/src/modes/components/tool-execution.test.ts
@@ -0,0 +1,101 @@
+import { beforeAll, describe, expect, it } from "bun:test";
+import type { AgentTool } from "@oh-my-pi/pi-agent-core";
+import { type Component, Text } from "@oh-my-pi/pi-tui";
+import { Settings } from "../../config/settings";
+import { getThemeByName, setThemeInstance, theme } from "../theme/theme";
+import { ToolExecutionComponent, type ToolExecutionUi } from "./tool-execution";
+
+class BoldTypeErrorComponent implements Component {
+	render(_width: number): readonly string[] {
+		throw new TypeError("th.bold is not a function");
+	}
+}
+
+function visibleText(lines: readonly string[]): string {
+	let text = lines.join("\n");
+	text = text.replace(/\x1b\]8;[^\x1b\x07]*(?:\x07|\x1b\\)/g, "");
+	text = text.replace(/\x1b\[[0-9;]*m/g, "");
+	return text;
+}
+
+describe("ToolExecutionComponent custom renderer failures", () => {
+	beforeAll(async () => {
+		await Settings.init({ inMemory: true });
+		const loaded = await getThemeByName("dark");
+		if (!loaded) throw new Error("theme unavailable");
+		setThemeInstance(loaded);
+	});
+
+	it("falls back to the custom tool label when a renderCall child component throws during render", () => {
+		const tool: AgentTool = {
+			name: "graphify_graph",
+			label: "Graphify Graph",
+			description: "renders a graph",
+			parameters: { type: "object", additionalProperties: true },
+			renderCall() {
+				return new BoldTypeErrorComponent();
+			},
+			async execute() {
+				return { content: [{ type: "text", text: "ok" }] };
+			},
+		};
+		const ui: ToolExecutionUi = {
+			requestRender() {},
+			requestComponentRender(_component: Component) {},
+			resetDisplay() {},
+		};
+		const component = new ToolExecutionComponent(
+			"graphify_graph",
+			{},
+			{ showImages: false },
+			tool,
+			ui,
+			process.cwd(),
+		);
+		let text = "";
+
+		expect(() => {
+			text = visibleText(component.render(80));
+		}).not.toThrow();
+		expect(text).toContain("Graphify Graph");
+	});
+
+	it("preserves raw result text when a renderResult child component throws during render", () => {
+		const rawResultText = "raw result survives child renderer failure";
+		const tool: AgentTool = {
+			name: "crashy_result_renderer",
+			label: "Crashy Result Renderer",
+			description: "renders result output",
+			parameters: { type: "object", additionalProperties: true },
+			renderCall() {
+				return new Text(theme.fg("toolTitle", theme.bold("Crashy Result Renderer")), 0, 0);
+			},
+			renderResult() {
+				return new BoldTypeErrorComponent();
+			},
+			async execute() {
+				return { content: [{ type: "text", text: rawResultText }] };
+			},
+		};
+		const ui: ToolExecutionUi = {
+			requestRender() {},
+			requestComponentRender(_component: Component) {},
+			resetDisplay() {},
+		};
+		const component = new ToolExecutionComponent(
+			"crashy_result_renderer",
+			{},
+			{ showImages: false },
+			tool,
+			ui,
+			process.cwd(),
+		);
+		component.updateResult({ content: [{ type: "text", text: rawResultText }] }, false);
+		let text = "";
+
+		expect(() => {
+			text = visibleText(component.render(80));
+		}).not.toThrow();
+		expect(text).toContain(rawResultText);
+	});
+});
diff --git a/packages/coding-agent/src/modes/components/tool-execution.ts b/packages/coding-agent/src/modes/components/tool-execution.ts
index 1fa927256..51e419f44 100644
--- a/packages/coding-agent/src/modes/components/tool-execution.ts
+++ b/packages/coding-agent/src/modes/components/tool-execution.ts
@@ -40,7 +40,7 @@ import {
 } from "../../tools/render-utils";
 import { type FirstResultViewportRepaint, toolRenderers } from "../../tools/renderers";
 import { TODO_STRIKE_TOTAL_FRAMES, type TodoToolDetails } from "../../tools/todo";
-import { isFramedBlockComponent, renderStatusLine, WidthAwareText } from "../../tui";
+import { isFramedBlockComponent, markFramedBlockComponent, renderStatusLine, WidthAwareText } from "../../tui";
 import { sanitizeWithOptionalSixelPassthrough } from "../../utils/sixel";
 import { renderDiff } from "./diff";
 
@@ -148,6 +148,68 @@ function getArgsWithStreamedTextInput(args: unknown): unknown {
 	return input === undefined ? args : { ...record, input };
 }
 
+type ToolRendererStage = "call" | "result";
+
+class SafeToolRendererComponent implements Component {
+	#toolName: string;
+	#stage: ToolRendererStage;
+	#component: Component;
+	#fallback: () => Component | undefined;
+	#warned = false;
+	readonly wantsKeyRelease: boolean | undefined;
+
+	constructor(
+		toolName: string,
+		stage: ToolRendererStage,
+		component: Component,
+		fallback: () => Component | undefined,
+	) {
+		this.#toolName = toolName;
+		this.#stage = stage;
+		this.#component = component;
+		this.#fallback = fallback;
+		this.wantsKeyRelease = component.wantsKeyRelease;
+		if (isFramedBlockComponent(component)) {
+			markFramedBlockComponent(this);
+		}
+	}
+
+	render(width: number): readonly string[] {
+		try {
+			return this.#component.render(width);
+		} catch (err) {
+			if (!this.#warned) {
+				this.#warned = true;
+				logger.warn("Tool renderer failed", { tool: this.#toolName, stage: this.#stage, error: String(err) });
+			}
+			return this.#fallback()?.render(width) ?? [];
+		}
+	}
+
+	handleInput(data: string): void {
+		const handleInput = this.#component.handleInput;
+		if (handleInput === undefined) return;
+		handleInput.call(this.#component, data);
+	}
+
+	invalidate(): void {
+		const invalidate = this.#component.invalidate;
+		if (invalidate === undefined) return;
+		invalidate.call(this.#component);
+	}
+
+	setIgnoreTight(ignore: boolean): void {
+		const setIgnoreTight = this.#component.setIgnoreTight;
+		if (setIgnoreTight === undefined) return;
+		setIgnoreTight.call(this.#component, ignore);
+	}
+
+	dispose(): void {
+		const dispose = this.#component.dispose;
+		if (dispose === undefined) return;
+		dispose.call(this.#component);
+	}
+}
 /**
  * Transcript-side probe telling a block whether it is still inside the live
  * (repaintable) region. Implemented by `TranscriptContainer`; injected rather
@@ -157,6 +219,14 @@ export interface TranscriptLiveRegionProbe {
 	isBlockInLiveRegion(component: Component): boolean;
 }
 
+/** Minimal TUI surface ToolExecutionComponent uses to schedule repaints and share image budget. */
+export interface ToolExecutionUi {
+	requestRender(): void;
+	requestComponentRender(component: Component): void;
+	resetDisplay(): void;
+	imageBudget?: TUI["imageBudget"];
+}
+
 export interface ToolExecutionOptions {
 	snapshots?: SnapshotStore;
 	showImages?: boolean; // default: true (only used if terminal supports images)
@@ -240,7 +310,7 @@ export class ToolExecutionComponent extends Container implements NativeScrollbac
 	// forcing the common image-free result to re-shape on every resize tick.
 	#renderedImageCount = 0;
 	#tool?: AgentTool;
-	#ui: TUI;
+	#ui: ToolExecutionUi;
 	#cwd: string;
 	#result?: {
 		content: Array<{ type: string; text?: string; data?: string; mimeType?: string }>;
@@ -308,7 +378,7 @@ export class ToolExecutionComponent extends Container implements NativeScrollbac
 		args: any,
 		options: ToolExecutionOptions = {},
 		tool: AgentTool | undefined,
-		ui: TUI,
+		ui: ToolExecutionUi,
 		cwd: string = getProjectDir(),
 		_toolCallId?: string,
 	) {
@@ -902,8 +972,17 @@ export class ToolExecutionComponent extends Container implements NativeScrollbac
 				if (tool.renderCall) {
 					try {
 						const callArgs = this.#getCallArgsForRender();
-						const callComponent = tool.renderCall(callArgs, this.#renderState, theme);
-						if (callComponent) this.#contentBox.addChild(callComponent as Component);
+						const callComponent = tool.renderCall(callArgs, this.#renderState, theme) as Component | undefined;
+						if (callComponent) {
+							this.#contentBox.addChild(
+								new SafeToolRendererComponent(
+									this.#toolName,
+									"call",
+									callComponent,
+									() => new Text(theme.fg("toolTitle", theme.bold(this.#toolLabel)), 0, 0),
+								),
+							);
+						}
 					} catch (err) {
 						logger.warn("Tool renderer failed", { tool: this.#toolName, error: String(err) });
 						// Fall back to default on error
@@ -934,7 +1013,15 @@ export class ToolExecutionComponent extends Container implements NativeScrollbac
 						theme,
 						this.#args,
 					);
-					if (resultComponent) this.#contentBox.addChild(resultComponent);
+					if (resultComponent) {
+						this.#contentBox.addChild(
+							new SafeToolRendererComponent(this.#toolName, "result", resultComponent, () => {
+								const output = this.#getTextOutput();
+								if (!output) return undefined;
+								return new Text(theme.fg("toolOutput", replaceTabs(output)), 0, 0);
+							}),
+						);
+					}
 				} catch (err) {
 					logger.warn("Tool renderer failed", { tool: this.#toolName, error: String(err) });
 					// Fall back to showing raw output on error
@@ -991,7 +1078,11 @@ export class ToolExecutionComponent extends Container implements NativeScrollbac
 							this.#renderState,
 							theme,
 						);
-						if (resultComponent) fileBox.addChild(resultComponent);
+						if (resultComponent) {
+							fileBox.addChild(
+								new SafeToolRendererComponent(this.#toolName, "result", resultComponent, () => undefined),
+							);
+						}
 					} catch (err) {
 						logger.warn("Tool renderer failed", { tool: this.#toolName, error: String(err) });
 					}
@@ -1038,7 +1129,16 @@ export class ToolExecutionComponent extends Container implements NativeScrollbac
 					try {
 						const callArgs = this.#getCallArgsForRender();
 						const callComponent = renderer.renderCall(callArgs, this.#renderState, theme);
-						if (callComponent) this.#contentBox.addChild(callComponent);
+						if (callComponent) {
+							this.#contentBox.addChild(
+								new SafeToolRendererComponent(
+									this.#toolName,
+									"call",
+									callComponent,
+									() => new Text(theme.fg("toolTitle", theme.bold(this.#toolLabel)), 0, 0),
+								),
+							);
+						}
 					} catch (err) {
 						logger.warn("Tool renderer failed", { tool: this.#toolName, error: String(err) });
 						// Fall back to default on error
@@ -1059,7 +1159,15 @@ export class ToolExecutionComponent extends Container implements NativeScrollbac
 							theme,
 							this.#getCallArgsForRender(),
 						);
-						if (resultComponent) this.#contentBox.addChild(resultComponent);
+						if (resultComponent) {
+							this.#contentBox.addChild(
+								new SafeToolRendererComponent(this.#toolName, "result", resultComponent, () => {
+									const output = this.#getTextOutput();
+									if (!output) return undefined;
+									return new Text(theme.fg("toolOutput", replaceTabs(output)), 0, 0);
+								}),
+							);
+						}
 					} catch (err) {
 						logger.warn("Tool renderer failed", { tool: this.#toolName, error: String(err) });
 						// Fall back to showing raw output on error