fix(cli): avoid os.cpus during startup prompt

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed Linux startup prompt construction to read the CPU model from `/proc/cpuinfo` instead of `os.cpus()`, avoiding per-core sysfs frequency probes on many-core hosts ([#4712](https://github.com/can1357/oh-my-pi/issues/4712)).
+
 ## [16.3.10] - 2026-07-06
 
 ### Changed

packages/coding-agent/src/system-prompt.test.ts

@@ -1,7 +1,8 @@
-import { describe, expect, it } from "bun:test";
+import { describe, expect, it, spyOn } from "bun:test";
 import * as fs from "node:fs/promises";
 import * as os from "node:os";
 import * as path from "node:path";
+import { buildSystemPrompt } from "./system-prompt";
 
 interface ProbeRunResult {
 	elapsedMs: number;
@@ -156,3 +157,35 @@ describe.skipIf(process.platform !== "linux")("system prompt GPU probe", () => {
 		expect(result.childElapsedMs).toBeLessThan(2000);
 	}, 15_000);
 });
+
+describe.skipIf(process.platform !== "linux")("system prompt CPU model", () => {
+	it("does not call os.cpus while building the workstation block", async () => {
+		const cpus = spyOn(os, "cpus").mockImplementation(() => [
+			{
+				model: "Synthetic Slow CPU",
+				speed: 0,
+				times: { user: 0, nice: 0, sys: 0, idle: 0, irq: 0 },
+			},
+		]);
+		try {
+			await buildSystemPrompt({
+				resolvedCustomPrompt: "Base prompt",
+				contextFiles: [],
+				skills: [],
+				rules: [],
+				workspaceTree: {
+					rootPath: import.meta.dir,
+					rendered: "",
+					truncated: false,
+					totalLines: 0,
+					agentsMdFiles: [],
+				},
+				activeRepoContext: null,
+			});
+
+			expect(cpus).not.toHaveBeenCalled();
+		} finally {
+			cpus.mockRestore();
+		}
+	});
+});

packages/coding-agent/src/system-prompt.ts

@@ -249,6 +249,21 @@ async function getCachedGpu(): Promise<string | undefined> {
 	await logger.time("getCachedGpu:saveGpuCache", saveGpuCache, { gpu });
 	return gpu ?? undefined;
 }
+
+async function getCpuModel(): Promise<string | undefined> {
+	if (process.platform !== "linux") return undefined;
+	try {
+		const cpuInfo = await Bun.file("/proc/cpuinfo").text();
+		const match = /^model name\s*:\s*(.+)$/m.exec(cpuInfo);
+		return match?.[1]?.trim() || undefined;
+	} catch (error) {
+		if (!isEnoent(error)) {
+			logger.debug("Could not read Linux CPU model", { error: String(error) });
+		}
+		return undefined;
+	}
+}
+
 /**
  * Kernel identity for the workstation block. Prefers the uname build string
  * from `os.version()`, but Bun on macOS 15+ (Darwin 24/25) returns the literal
@@ -263,13 +278,10 @@ function getKernelIdentity(): string {
 	return `${os.type()} ${os.release()}`.trim();
 }
 
-function getEnvironmentInfo(gpu: string | undefined): Array<{ label: string; value: string }> {
-	let cpuModel: string | undefined;
-	try {
-		cpuModel = os.cpus()[0]?.model;
-	} catch {
-		cpuModel = undefined;
-	}
+function getEnvironmentInfo(
+	cpuModel: string | undefined,
+	gpu: string | undefined,
+): Array<{ label: string; value: string }> {
 	const entries: Array<{ label: string; value: string | undefined }> = [
 		{ label: "OS", value: `${os.platform()} ${os.release()}` },
 		{ label: "Distro", value: os.type() },
@@ -549,6 +561,7 @@ export async function buildSystemPrompt(options: BuildSystemPromptOptions = {}):
 			agentsMdFiles: [],
 		} satisfies WorkspaceTree,
 		activeRepoContext: null as ActiveRepoContext | null,
+		cpuModel: undefined as string | undefined,
 		gpu: undefined as string | undefined,
 	};
 
@@ -619,6 +632,7 @@ export async function buildSystemPrompt(options: BuildSystemPromptOptions = {}):
 		providedActiveRepoContext !== undefined
 			? Promise.resolve(providedActiveRepoContext)
 			: logger.time("resolveActiveRepoContext", () => resolveActiveRepoContext(resolvedCwd));
+	const cpuModelPromise = logger.time("getCpuModel", getCpuModel);
 	const gpuPromise = logger.time("getCachedGpu", getCachedGpu);
 
 	const [
@@ -629,6 +643,7 @@ export async function buildSystemPrompt(options: BuildSystemPromptOptions = {}):
 		skills,
 		workspaceTree,
 		activeRepoContext,
+		cpuModel,
 		gpu,
 	] = await Promise.all([
 		withDeadline(
@@ -652,6 +667,7 @@ export async function buildSystemPrompt(options: BuildSystemPromptOptions = {}):
 		withDeadline("loadSkills", skillsPromise, prepDefaults.skills),
 		withDeadline("buildWorkspaceTree", workspaceTreePromise, prepDefaults.workspaceTree),
 		withDeadline("resolveActiveRepoContext", activeRepoContextPromise, prepDefaults.activeRepoContext),
+		withDeadline("getCpuModel", cpuModelPromise, prepDefaults.cpuModel),
 		withDeadline("getCachedGpu", gpuPromise, prepDefaults.gpu),
 	]);
 	clearTimeout(deadlineTimer);
@@ -732,7 +748,7 @@ export async function buildSystemPrompt(options: BuildSystemPromptOptions = {}):
 	];
 	const injectedAlwaysApplyRules = dedupeAlwaysApplyRules(alwaysApplyRules, promptSources);
 
-	const environment = getEnvironmentInfo(gpu);
+	const environment = getEnvironmentInfo(cpuModel, gpu);
 	const data = {
 		systemPromptCustomization: effectiveSystemPromptCustomization,
 		customPrompt: resolvedCustomPrompt,