cli: write groups.cache for shell-completion --group enumeration

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/relicario-cli/tests/smart_inputs.rs

@@ -1,3 +1,5 @@
+mod common;
+
 use assert_cmd::Command;
 use predicates::str::contains;
 
@@ -28,3 +30,76 @@ fn completions_fish_emits_script() {
         .success()
         .stdout(contains("complete -c relicario"));
 }
+
+#[test]
+fn list_command_refreshes_groups_cache() {
+    let v = common::TestVault::init();
+
+    let out = v.run(&[
+        "add", "login",
+        "--title", "T",
+        "--username", "u",
+        "--group", "work",
+        "--password", "hunter2",
+    ]);
+    assert!(out.status.success(), "add failed: {:?}", out);
+
+    let out = v.run(&["list"]);
+    assert!(out.status.success(), "list failed: {:?}", out);
+
+    let cache_path = v.path().join(".relicario/groups.cache");
+    let cache = std::fs::read_to_string(&cache_path)
+        .unwrap_or_else(|e| panic!("groups.cache not found at {}: {e}", cache_path.display()));
+    assert!(
+        cache.lines().any(|l| l == "work"),
+        "expected 'work' in groups.cache, got: {cache:?}"
+    );
+}
+
+#[test]
+fn no_groups_cache_env_var_suppresses_write() {
+    use std::process::{Command as StdCommand, Stdio};
+    use assert_cmd::cargo::CommandCargoExt as _;
+
+    let v = common::TestVault::init();
+
+    // Add with the env var set so no cache is created by add either.
+    let out = StdCommand::cargo_bin("relicario").unwrap()
+        .current_dir(v.path())
+        .env("RELICARIO_IMAGE", &v.reference_image)
+        .env("RELICARIO_TEST_PASSPHRASE", &v.passphrase)
+        .env("RELICARIO_NO_GROUPS_CACHE", "1")
+        .args([
+            "add", "login",
+            "--title", "T2",
+            "--username", "u",
+            "--group", "personal",
+            "--password", "hunter2",
+        ])
+        .stdin(Stdio::null())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .output()
+        .unwrap();
+    assert!(out.status.success(), "add failed: {:?}", out);
+
+    // Run list with RELICARIO_NO_GROUPS_CACHE=1 — cache must NOT be written.
+    let out = StdCommand::cargo_bin("relicario").unwrap()
+        .current_dir(v.path())
+        .env("RELICARIO_IMAGE", &v.reference_image)
+        .env("RELICARIO_TEST_PASSPHRASE", &v.passphrase)
+        .env("RELICARIO_NO_GROUPS_CACHE", "1")
+        .args(["list"])
+        .stdin(Stdio::null())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .output()
+        .unwrap();
+    assert!(out.status.success(), "list failed: {:?}", out);
+
+    let cache_path = v.path().join(".relicario/groups.cache");
+    assert!(
+        !cache_path.exists(),
+        "groups.cache should not exist when RELICARIO_NO_GROUPS_CACHE=1"
+    );
+}