Add JSON output for plugin subcommands (#26631)

## Summary
- Follow-up to #25330 and #26417
- Add `--json` output for `codex plugin add` and `codex plugin remove`
- Add `--json` output for `codex plugin marketplace
add/list/upgrade/remove`
- Keep existing human-readable output unchanged
- Keep existing error handling/stderr behavior unchanged; `--json`
changes successful stdout output only
- Align marketplace add/remove JSON field names with the existing
app-server protocol shape
- Add CLI coverage for plugin and marketplace JSON outputs

## Validation
- `just fmt`
- `just fix -p codex-cli`
- `just test -p codex-cli`

codex-rs/cli/src/marketplace_cmd.rs

@@ -7,11 +7,14 @@ use codex_core::config::find_codex_home;
 use codex_core_plugins::PluginMarketplaceUpgradeOutcome;
 use codex_core_plugins::PluginsManager;
 use codex_core_plugins::marketplace::marketplace_root_dir;
+use codex_core_plugins::marketplace_add::MarketplaceAddOutcome;
 use codex_core_plugins::marketplace_add::MarketplaceAddRequest;
 use codex_core_plugins::marketplace_add::add_marketplace;
+use codex_core_plugins::marketplace_remove::MarketplaceRemoveOutcome;
 use codex_core_plugins::marketplace_remove::MarketplaceRemoveRequest;
 use codex_core_plugins::marketplace_remove::remove_marketplace;
 use codex_utils_cli::CliConfigOverrides;
+use serde::Serialize;
 use std::collections::HashSet;
 
 use crate::plugin_cmd::configured_marketplace_snapshot_issues;
@@ -32,7 +35,7 @@ enum MarketplaceSubcommand {
     Add(AddMarketplaceArgs),
 
     /// List plugin marketplaces Codex is currently considering and their roots.
-    List,
+    List(ListMarketplaceArgs),
 
     /// Refresh configured Git marketplace snapshots.
     ///
@@ -64,6 +67,18 @@ struct AddMarketplaceArgs {
         action = clap::ArgAction::Append
     )]
     sparse_paths: Vec<String>,
+
+    /// Output add result as JSON.
+    #[arg(long = "json")]
+    json: bool,
+}
+
+#[derive(Debug, Parser)]
+#[command(bin_name = "codex plugin marketplace list")]
+struct ListMarketplaceArgs {
+    /// Output marketplace list as JSON.
+    #[arg(long = "json")]
+    json: bool,
 }
 
 #[derive(Debug, Parser)]
@@ -75,6 +90,10 @@ struct UpgradeMarketplaceArgs {
     /// Optional configured marketplace name to upgrade. Omit to upgrade all Git marketplaces.
     #[arg(value_name = "MARKETPLACE_NAME")]
     marketplace_name: Option<String>,
+
+    /// Output upgrade result as JSON.
+    #[arg(long = "json")]
+    json: bool,
 }
 
 #[derive(Debug, Parser)]
@@ -86,6 +105,10 @@ struct RemoveMarketplaceArgs {
     /// Configured marketplace name to remove.
     #[arg(value_name = "MARKETPLACE_NAME")]
     marketplace_name: String,
+
+    /// Output remove result as JSON.
+    #[arg(long = "json")]
+    json: bool,
 }
 
 impl MarketplaceCli {
@@ -101,7 +124,7 @@ impl MarketplaceCli {
 
         match subcommand {
             MarketplaceSubcommand::Add(args) => run_add(args).await?,
-            MarketplaceSubcommand::List => run_list(overrides).await?,
+            MarketplaceSubcommand::List(args) => run_list(overrides, args).await?,
             MarketplaceSubcommand::Upgrade(args) => run_upgrade(overrides, args).await?,
             MarketplaceSubcommand::Remove(args) => run_remove(args).await?,
         }
@@ -115,6 +138,7 @@ async fn run_add(args: AddMarketplaceArgs) -> Result<()> {
         source,
         ref_name,
         sparse_paths,
+        json,
     } = args;
 
     let codex_home = find_codex_home().context("failed to resolve CODEX_HOME")?;
@@ -128,6 +152,12 @@ async fn run_add(args: AddMarketplaceArgs) -> Result<()> {
     )
     .await?;
 
+    if json {
+        let output = JsonMarketplaceAddOutput::from_outcome(outcome);
+        println!("{}", serde_json::to_string_pretty(&output)?);
+        return Ok(());
+    }
+
     if outcome.already_added {
         println!(
             "Marketplace `{}` is already added from {}.",
@@ -147,7 +177,25 @@ async fn run_add(args: AddMarketplaceArgs) -> Result<()> {
     Ok(())
 }
 
-async fn run_list(overrides: Vec<(String, toml::Value)>) -> Result<()> {
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct JsonMarketplaceAddOutput {
+    marketplace_name: String,
+    installed_root: String,
+    already_added: bool,
+}
+
+impl JsonMarketplaceAddOutput {
+    fn from_outcome(outcome: MarketplaceAddOutcome) -> Self {
+        Self {
+            marketplace_name: outcome.marketplace_name,
+            installed_root: outcome.installed_root.as_path().display().to_string(),
+            already_added: outcome.already_added,
+        }
+    }
+}
+
+async fn run_list(overrides: Vec<(String, toml::Value)>, args: ListMarketplaceArgs) -> Result<()> {
     let config = Config::load_with_cli_overrides(overrides)
         .await
         .context("failed to load configuration")?;
@@ -191,6 +239,12 @@ async fn run_list(overrides: Vec<(String, toml::Value)>) -> Result<()> {
         bail!("failed to load marketplace(s):\n{issue_lines}");
     }
     let marketplaces = marketplace_listing.marketplaces;
+    if args.json {
+        let output = JsonMarketplaceListOutput::from_marketplaces(marketplaces);
+        println!("{}", serde_json::to_string_pretty(&output)?);
+        return Ok(());
+    }
+
     if marketplaces.is_empty() {
         println!("No plugin marketplaces in scope.");
         return Ok(());
@@ -227,11 +281,48 @@ async fn run_list(overrides: Vec<(String, toml::Value)>) -> Result<()> {
     Ok(())
 }
 
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct JsonMarketplaceListOutput {
+    marketplaces: Vec<JsonMarketplaceListEntry>,
+}
+
+impl JsonMarketplaceListOutput {
+    fn from_marketplaces(marketplaces: Vec<codex_core_plugins::marketplace::Marketplace>) -> Self {
+        let mut seen_roots = HashSet::new();
+        let marketplaces = marketplaces
+            .into_iter()
+            .filter_map(|marketplace| {
+                let root = marketplace_root_dir(&marketplace.path).ok()?;
+                if !seen_roots.insert(root.clone()) {
+                    return None;
+                }
+                Some(JsonMarketplaceListEntry {
+                    name: marketplace.name,
+                    root: root.display().to_string(),
+                })
+            })
+            .collect();
+
+        Self { marketplaces }
+    }
+}
+
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct JsonMarketplaceListEntry {
+    name: String,
+    root: String,
+}
+
 async fn run_upgrade(
     overrides: Vec<(String, toml::Value)>,
     args: UpgradeMarketplaceArgs,
 ) -> Result<()> {
-    let UpgradeMarketplaceArgs { marketplace_name } = args;
+    let UpgradeMarketplaceArgs {
+        marketplace_name,
+        json,
+    } = args;
     let config = Config::load_with_cli_overrides(overrides)
         .await
         .context("failed to load configuration")?;
@@ -241,11 +332,18 @@ async fn run_upgrade(
     let outcome = manager
         .upgrade_configured_marketplaces_for_config(&plugins_input, marketplace_name.as_deref())
         .map_err(anyhow::Error::msg)?;
-    print_upgrade_outcome(&outcome, marketplace_name.as_deref())
+    if json {
+        print_upgrade_outcome_json(&outcome)
+    } else {
+        print_upgrade_outcome(&outcome, marketplace_name.as_deref())
+    }
 }
 
 async fn run_remove(args: RemoveMarketplaceArgs) -> Result<()> {
-    let RemoveMarketplaceArgs { marketplace_name } = args;
+    let RemoveMarketplaceArgs {
+        marketplace_name,
+        json,
+    } = args;
     let codex_home = find_codex_home().context("failed to resolve CODEX_HOME")?;
     let outcome = remove_marketplace(
         codex_home.to_path_buf(),
@@ -253,6 +351,12 @@ async fn run_remove(args: RemoveMarketplaceArgs) -> Result<()> {
     )
     .await?;
 
+    if json {
+        let output = JsonMarketplaceRemoveOutput::from_outcome(outcome);
+        println!("{}", serde_json::to_string_pretty(&output)?);
+        return Ok(());
+    }
+
     println!("Removed marketplace `{}`.", outcome.marketplace_name);
     if let Some(installed_root) = outcome.removed_installed_root {
         println!(
@@ -264,6 +368,76 @@ async fn run_remove(args: RemoveMarketplaceArgs) -> Result<()> {
     Ok(())
 }
 
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct JsonMarketplaceRemoveOutput {
+    marketplace_name: String,
+    installed_root: Option<String>,
+}
+
+impl JsonMarketplaceRemoveOutput {
+    fn from_outcome(outcome: MarketplaceRemoveOutcome) -> Self {
+        Self {
+            marketplace_name: outcome.marketplace_name,
+            installed_root: outcome
+                .removed_installed_root
+                .map(|root| root.as_path().display().to_string()),
+        }
+    }
+}
+
+fn print_upgrade_outcome_json(outcome: &PluginMarketplaceUpgradeOutcome) -> Result<()> {
+    for error in &outcome.errors {
+        eprintln!(
+            "Failed to upgrade marketplace `{}`: {}",
+            error.marketplace_name, error.message
+        );
+    }
+    if !outcome.all_succeeded() {
+        bail!("{} upgrade failure(s) occurred.", outcome.errors.len());
+    }
+
+    let output = JsonMarketplaceUpgradeOutput::from_outcome(outcome);
+    println!("{}", serde_json::to_string_pretty(&output)?);
+    Ok(())
+}
+
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct JsonMarketplaceUpgradeOutput {
+    selected_marketplaces: Vec<String>,
+    upgraded_roots: Vec<String>,
+    errors: Vec<JsonMarketplaceUpgradeError>,
+}
+
+impl JsonMarketplaceUpgradeOutput {
+    fn from_outcome(outcome: &PluginMarketplaceUpgradeOutcome) -> Self {
+        Self {
+            selected_marketplaces: outcome.selected_marketplaces.clone(),
+            upgraded_roots: outcome
+                .upgraded_roots
+                .iter()
+                .map(|root| root.display().to_string())
+                .collect(),
+            errors: outcome
+                .errors
+                .iter()
+                .map(|error| JsonMarketplaceUpgradeError {
+                    marketplace_name: error.marketplace_name.clone(),
+                    message: error.message.clone(),
+                })
+                .collect(),
+        }
+    }
+}
+
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct JsonMarketplaceUpgradeError {
+    marketplace_name: String,
+    message: String,
+}
+
 fn print_upgrade_outcome(
     outcome: &PluginMarketplaceUpgradeOutcome,
     marketplace_name: Option<&str>,