refactor: simplify error formatter in web-server modal

tests/backend/shell-escaping.test.ts

@@ -0,0 +1,43 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { escapeShellArg } from "../../src/server/services/ssh-services/internal/shell";
+import { formatServerActionError } from "../../src/server/routes/server-action-errors";
+
+test("escapeShellArg preserves single quotes inside bash -lc payloads", () => {
+  const command =
+    "docker ps --format '{{.Names}}|{{.Image}}|{{.Ports}}' 2>/dev/null | grep -E '0\\.0\\.0\\.0:(80|443)|:::(80|443)' || true";
+
+  assert.equal(
+    escapeShellArg(command),
+    "'docker ps --format '\\''{{.Names}}|{{.Image}}|{{.Ports}}'\\'' 2>/dev/null | grep -E '\\''0\\.0\\.0\\.0:(80|443)|:::(80|443)'\\'' || true'",
+  );
+});
+
+test("server action errors hide raw remote shell syntax failures", () => {
+  const message = formatServerActionError(
+    new Error(
+      "Command failed: bash: -c: line 1: syntax error near unexpected token `|'",
+    ),
+    "Failed to restart service apache2",
+  );
+
+  assert.equal(
+    message,
+    "The remote host rejected the generated shell command before it could finish. Refresh the server snapshot and retry the action.",
+  );
+});
+
+test("server action errors normalize host port conflicts", () => {
+  const message = formatServerActionError(
+    new Error(
+      "Command failed: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)",
+    ),
+    "Failed to restart web server",
+  );
+
+  assert.equal(
+    message,
+    "The service could not start because port 80 or 443 is already in use by another host process or Docker container.",
+  );
+});