Fix empty self-rendered tool rows

closes #5299

packages/coding-agent/CHANGELOG.md

@@ -13,6 +13,7 @@
 - Fixed SDK embedding in bundled Node apps failing with `ENOENT` when `package.json` is not present next to the bundle entrypoint. The package metadata reader now gracefully handles missing `package.json` by using defaults, enabling `createAgentSession()` without requiring package-adjacent files at runtime ([#5226](https://github.com/earendil-works/pi/issues/5226)).
 - Fixed HTTP timeout setting not being respected for non-Codex providers (e.g., llama.cpp via OpenAI-compatible API). The `httpIdleTimeoutMs` setting (set via `/settings` HTTP timeout) now applies as the default SDK request timeout for all providers that support it, not just OpenAI Codex Responses. Disabling the timeout (HTTP timeout = false) now correctly disables SDK timeouts for all supported providers by sending a maximum int32 value (effectively infinite) instead of 0, since SDKs treat timeout=0 as an immediate timeout ([#5294](https://github.com/earendil-works/pi/issues/5294)).
 - Fixed opening and listing very large JSONL session files by reading session entries line-by-line instead of materializing the full file as one string ([#5231](https://github.com/earendil-works/pi/issues/5231)).
+- Fixed `renderShell: "self"` tool renderers that emit no component lines leaving a blank chat row ([#5299](https://github.com/earendil-works/pi/issues/5299)).
 
 ## [0.78.0] - 2026-05-29
 

packages/coding-agent/src/modes/interactive/components/tool-execution.ts

@@ -222,6 +222,31 @@ export class ToolExecutionComponent extends Container {
 		if (this.hideComponent) {
 			return [];
 		}
+
+		if (this.hasRendererDefinition() && this.getRenderShell() === "self") {
+			const contentLines = this.selfRenderContainer.render(width);
+			if (contentLines.length === 0 && this.imageComponents.length === 0) {
+				return [];
+			}
+
+			const lines: string[] = [];
+			if (contentLines.length > 0) {
+				lines.push("");
+				lines.push(...contentLines);
+			}
+			for (let i = 0; i < this.imageComponents.length; i++) {
+				const spacer = this.imageSpacers[i];
+				if (spacer) {
+					lines.push(...spacer.render(width));
+				}
+				const imageComponent = this.imageComponents[i];
+				if (imageComponent) {
+					lines.push(...imageComponent.render(width));
+				}
+			}
+			return lines;
+		}
+
 		return super.render(width);
 	}
 

packages/coding-agent/test/tool-execution-component.test.ts

@@ -67,6 +67,37 @@ describe("ToolExecutionComponent parity", () => {
 		expect(rendered).toContain("custom result");
 	});
 
+	test("self-rendered empty tool rows take no layout space", () => {
+		const toolDefinition: ToolDefinition = {
+			...createBaseToolDefinition(),
+			renderShell: "self",
+			renderCall: () => new Text("", 0, 0),
+			renderResult: () => new Text("", 0, 0),
+		};
+
+		const component = new ToolExecutionComponent(
+			"custom_tool",
+			"tool-empty-self-render",
+			{},
+			{},
+			toolDefinition,
+			createFakeTui(),
+			process.cwd(),
+		);
+		expect(component.render(120)).toEqual([]);
+
+		component.updateResult(
+			{
+				content: [],
+				details: {},
+				isError: false,
+			},
+			false,
+		);
+
+		expect(component.render(120)).toEqual([]);
+	});
+
 	test("uses built-in rendering for built-in overrides without custom renderers", () => {
 		const overrideDefinition: ToolDefinition = {
 			...createBaseToolDefinition("edit"),