fix(coding-agent): skip no-op git package reinstalls

closes #2503

packages/coding-agent/src/core/package-manager.ts

@@ -1278,6 +1278,23 @@ export class DefaultPackageManager implements PackageManager {
 		return match[1];
 	}
 
+	private async getLocalGitUpdateTarget(installedPath: string): Promise<{ ref: string; head: string }> {
+		try {
+			const head = await this.runCommandCapture("git", ["rev-parse", "@{upstream}"], {
+				cwd: installedPath,
+				timeoutMs: NETWORK_TIMEOUT_MS,
+			});
+			return { ref: "@{upstream}", head };
+		} catch {
+			await this.runCommand("git", ["remote", "set-head", "origin", "-a"], { cwd: installedPath }).catch(() => {});
+			const head = await this.runCommandCapture("git", ["rev-parse", "origin/HEAD"], {
+				cwd: installedPath,
+				timeoutMs: NETWORK_TIMEOUT_MS,
+			});
+			return { ref: "origin/HEAD", head };
+		}
+	}
+
 	private async getGitUpstreamRef(installedPath: string): Promise<string | undefined> {
 		try {
 			const upstream = await this.runCommandCapture("git", ["rev-parse", "--abbrev-ref", "@{upstream}"], {
@@ -1463,14 +1480,17 @@ export class DefaultPackageManager implements PackageManager {
 		// Fetch latest from remote (handles force-push by getting new history)
 		await this.runCommand("git", ["fetch", "--prune", "origin"], { cwd: targetDir });
 
-		// Reset to tracking branch. Fall back to origin/HEAD when no upstream is configured.
-		try {
-			await this.runCommand("git", ["reset", "--hard", "@{upstream}"], { cwd: targetDir });
-		} catch {
-			await this.runCommand("git", ["remote", "set-head", "origin", "-a"], { cwd: targetDir }).catch(() => {});
-			await this.runCommand("git", ["reset", "--hard", "origin/HEAD"], { cwd: targetDir });
+		const localHead = await this.runCommandCapture("git", ["rev-parse", "HEAD"], {
+			cwd: targetDir,
+			timeoutMs: NETWORK_TIMEOUT_MS,
+		});
+		const target = await this.getLocalGitUpdateTarget(targetDir);
+		if (localHead.trim() === target.head.trim()) {
+			return;
 		}
 
+		await this.runCommand("git", ["reset", "--hard", target.ref], { cwd: targetDir });
+
 		// Clean untracked files (extensions should be pristine)
 		await this.runCommand("git", ["clean", "-fdx"], { cwd: targetDir });