diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 479b5560..582015c0 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -14,6 +14,7 @@
 - Fixed AgentSession retry, compaction, and event settlement to use the awaited agent lifecycle instead of a separate event queue, and added `willRetry` to `agent_end` session events.
 - Fixed the subagent extension's parallel mode to return useful per-task output and failed-task diagnostics to the parent model instead of 100-character previews ([#4710](https://github.com/earendil-works/pi/issues/4710)).
 - Fixed Windows local bash execution to hide helper console windows when launched from background SDK processes ([#4699](https://github.com/earendil-works/pi/issues/4699)).
+- Fixed managed npm extension folders to set cloud-sync ignore metadata where supported ([#4763](https://github.com/earendil-works/pi/issues/4763)).
 
 ## [0.75.3] - 2026-05-18
 
diff --git a/packages/coding-agent/src/core/package-manager.ts b/packages/coding-agent/src/core/package-manager.ts
index 59d53427..90c41942 100644
--- a/packages/coding-agent/src/core/package-manager.ts
+++ b/packages/coding-agent/src/core/package-manager.ts
@@ -30,7 +30,7 @@ import { minimatch } from "minimatch";
 import { CONFIG_DIR_NAME } from "../config.ts";
 import { spawnProcess, spawnProcessSync } from "../utils/child-process.ts";
 import { type GitSource, parseGitUrl } from "../utils/git.ts";
-import { canonicalizePath, isLocalPath } from "../utils/paths.ts";
+import { canonicalizePath, isLocalPath, markPathIgnoredByCloudSync } from "../utils/paths.ts";
 import { isStdoutTakenOver } from "./output-guard.ts";
 import type { PackageSource, SettingsManager } from "./settings-manager.ts";
 
@@ -1822,6 +1822,7 @@ export class DefaultPackageManager implements PackageManager {
 		if (!existsSync(installRoot)) {
 			mkdirSync(installRoot, { recursive: true });
 		}
+		markPathIgnoredByCloudSync(installRoot);
 		this.ensureGitIgnore(installRoot);
 		const packageJsonPath = join(installRoot, "package.json");
 		if (!existsSync(packageJsonPath)) {
diff --git a/packages/coding-agent/src/utils/paths.ts b/packages/coding-agent/src/utils/paths.ts
index ef36de7a..fd8d176e 100644
--- a/packages/coding-agent/src/utils/paths.ts
+++ b/packages/coding-agent/src/utils/paths.ts
@@ -1,5 +1,6 @@
 import { realpathSync } from "node:fs";
 import { isAbsolute, relative, resolve as resolvePath, sep } from "node:path";
+import { spawnProcessSync } from "./child-process.ts";
 
 /**
  * Resolve a path to its canonical (real) form, following symlinks.
@@ -55,3 +56,20 @@ export function formatPathRelativeToCwdOrAbsolute(filePath: string, cwd: string)
 	const absolutePath = resolveAgainstCwd(filePath, cwd);
 	return (getCwdRelativePath(absolutePath, cwd) ?? absolutePath).split(sep).join("/");
 }
+
+export function markPathIgnoredByCloudSync(path: string): void {
+	const attrs =
+		process.platform === "darwin"
+			? ["com.dropbox.ignored", "com.apple.fileprovider.ignore#P"]
+			: process.platform === "linux"
+				? ["user.com.dropbox.ignored"]
+				: [];
+
+	for (const attr of attrs) {
+		if (process.platform === "darwin") {
+			spawnProcessSync("xattr", ["-w", attr, "1", path], { encoding: "utf-8", stdio: "ignore" });
+		} else {
+			spawnProcessSync("setfattr", ["-n", attr, "-v", "1", path], { encoding: "utf-8", stdio: "ignore" });
+		}
+	}
+}