[codex] Add plugin list JSON output (#25330)

## Summary
- add `--json` output to `codex plugin list` with `installed` and
`available` arrays
- add `--available` for JSON output only; using it without `--json` is
rejected
- keep the existing non-JSON table output unchanged
- add CLI coverage for JSON installed/available output and the
`--available`/`--json` requirement

## Validation
- `just test -p codex-cli plugin_list`
- `just fix -p codex-cli`
- `git diff --check`

Note: `just fmt` ran Rust formatting first, then failed in the Python
ruff step because `openai-codex-cli-bin==0.132.0` has no wheel for this
Linux platform.

codex-rs/cli/tests/plugin_cli.rs

@@ -4,6 +4,8 @@ use codex_config::MarketplaceConfigUpdate;
 use codex_config::record_user_marketplace;
 use predicates::prelude::PredicateBooleanExt;
 use predicates::str::contains;
+use pretty_assertions::assert_eq;
+use serde_json::json;
 use std::path::Path;
 use tempfile::TempDir;
 
@@ -489,6 +491,103 @@ async fn plugin_list_prints_plugins_in_a_table() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn plugin_list_json_prints_available_plugins_when_requested() -> Result<()> {
+    let (codex_home, source) = setup_local_marketplace()?;
+    let plugin_path = source.path().join("plugins").join("sample");
+
+    let assert = codex_command(codex_home.path())?
+        .args(["plugin", "list", "--available", "--json"])
+        .assert()
+        .success();
+    let stdout = assert.get_output().stdout.as_slice();
+    let actual: serde_json::Value = serde_json::from_slice(stdout)?;
+
+    assert_eq!(
+        actual,
+        json!({
+            "installed": [],
+            "available": [
+                {
+                    "pluginId": "sample@debug",
+                    "name": "sample",
+                    "marketplaceName": "debug",
+                    "version": "1.2.3",
+                    "installed": false,
+                    "enabled": false,
+                    "source": {
+                        "source": "local",
+                        "path": plugin_path.display().to_string(),
+                    },
+                    "installPolicy": "AVAILABLE",
+                    "authPolicy": "ON_INSTALL",
+                },
+            ],
+        })
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn plugin_list_json_prints_installed_plugins() -> Result<()> {
+    let (codex_home, source) = setup_local_marketplace()?;
+    let plugin_path = source.path().join("plugins").join("sample");
+
+    codex_command(codex_home.path())?
+        .args(["plugin", "add", "sample@debug"])
+        .assert()
+        .success();
+
+    let assert = codex_command(codex_home.path())?
+        .args(["plugin", "list", "--json"])
+        .assert()
+        .success();
+    let stdout = assert.get_output().stdout.as_slice();
+    let actual: serde_json::Value = serde_json::from_slice(stdout)?;
+
+    assert_eq!(
+        actual,
+        json!({
+            "installed": [
+                {
+                    "pluginId": "sample@debug",
+                    "name": "sample",
+                    "marketplaceName": "debug",
+                    "version": "1.2.3",
+                    "installed": true,
+                    "enabled": true,
+                    "source": {
+                        "source": "local",
+                        "path": plugin_path.display().to_string(),
+                    },
+                    "installPolicy": "AVAILABLE",
+                    "authPolicy": "ON_INSTALL",
+                },
+            ],
+            "available": [],
+        })
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn plugin_list_available_requires_json() -> Result<()> {
+    let (codex_home, _source) = setup_local_marketplace()?;
+
+    codex_command(codex_home.path())?
+        .args(["plugin", "list", "--available"])
+        .assert()
+        .failure()
+        .stderr(contains(
+            "the following required arguments were not provided",
+        ))
+        .stderr(contains("--json"));
+
+    Ok(())
+}
+
 #[tokio::test]
 async fn plugin_list_shows_installed_version_when_plugin_is_installed() -> Result<()> {
     let (codex_home, _source) = setup_local_marketplace()?;