feat(slash): /theme picker with live preview

CLAUDE.md

@@ -84,7 +84,8 @@ ox                                          # Start an interactive session
 │   ├── picker.rs                           # ModelEffortPicker — combined model + effort modal; emits a single SwapConfig
 │   ├── registry.rs                         # SlashCommand trait + SlashOutcome + BUILT_INS slice + alias-aware lookup
 │   ├── status.rs                           # /status — opens StatusModal
-│   └── status_modal.rs                     # StatusModal — read-only kv-overview of the live session (Esc / Enter close)
+│   ├── status_modal.rs                     # StatusModal — read-only kv-overview of the live session (Esc / Enter close)
+│   └── theme.rs                            # /theme — bare opens the picker (live preview); `/theme <name>` validates against the curated roster and swaps
 ├── tool.rs                                 # Tool trait, registry, definitions
 ├── tool/
 │   ├── bash.rs                             # Shell command execution with timeout

crates/oxide-code/src/agent.rs

@@ -264,7 +264,9 @@ where
                 Some(
                     action @ (UserAction::ConfirmExit
                     | UserAction::Clear
-                    | UserAction::SwapConfig { .. }),
+                    | UserAction::SwapConfig { .. }
+                    | UserAction::PreviewTheme { .. }
+                    | UserAction::SwapTheme { .. }),
                 ) => warn!("dropped mid-turn action: {action:?}"),
             },
             output = &mut fut => return Ok(output),

crates/oxide-code/src/agent/event.rs

@@ -77,6 +77,15 @@ pub(crate) enum UserAction {
         model: Option<ResolvedModelId>,
         effort: Option<Effort>,
     },
+    /// TUI-only: live-preview the picker's highlighted theme without committing it. Cursor moves
+    /// in the `/theme` modal emit this; cancelling the modal restores the snapshot taken on open.
+    PreviewTheme {
+        name: String,
+    },
+    /// TUI-only: commit a theme swap for the rest of the session. Restart returns to user config.
+    SwapTheme {
+        name: String,
+    },
     Cancel,
     /// TUI-only; agent loop ignores this.
     ConfirmExit,

crates/oxide-code/src/client/anthropic/testing.rs

@@ -18,6 +18,7 @@ pub(crate) fn test_config(base_url: impl Into<String>, auth: Auth, model: &str)
         thinking: None,
         show_thinking: false,
         theme: Theme::default(),
+        theme_name: "mocha".to_owned(),
     }
 }
 

crates/oxide-code/src/config.rs

@@ -17,6 +17,8 @@ use crate::util::env;
 
 const DEFAULT_MODEL: &str = "claude-opus-4-7[1m]";
 const DEFAULT_BASE_URL: &str = "https://api.anthropic.com";
+/// Mirrors the fallback `loader::resolve_theme` applies when no `[tui.theme] base` is set.
+pub(crate) const DEFAULT_THEME: &str = "mocha";
 
 // ── Auth ──
 
@@ -49,6 +51,9 @@ pub(crate) struct ConfigSnapshot {
     pub(crate) max_tokens: u32,
     pub(crate) prompt_cache_ttl: PromptCacheTtl,
     pub(crate) show_thinking: bool,
+    /// Resolved theme base name — built-in catalogue key or filesystem path. `/theme` reads this
+    /// to mark the active row in the picker.
+    pub(crate) theme_name: String,
 }
 
 // ── ThinkingConfig ──
@@ -183,6 +188,9 @@ pub(crate) struct Config {
     pub(crate) thinking: Option<ThinkingConfig>,
     pub(crate) show_thinking: bool,
     pub(crate) theme: Theme,
+    /// Built-in catalogue key (e.g. `"mocha"`) or filesystem path; mirrors `[tui.theme] base`,
+    /// falling back to [`DEFAULT_THEME`] when unset.
+    pub(crate) theme_name: String,
 }
 
 impl Config {
@@ -245,6 +253,10 @@ impl Config {
             None => client.prompt_cache_ttl.unwrap_or(PromptCacheTtl::OneHour),
         };
 
+        let theme_name = theme_config
+            .base
+            .clone()
+            .unwrap_or_else(|| DEFAULT_THEME.to_owned());
         let theme = theme::resolve_theme(
             theme_config.base.as_deref(),
             &theme_config.overrides.unwrap_or_default(),
@@ -260,6 +272,7 @@ impl Config {
             thinking,
             show_thinking,
             theme,
+            theme_name,
         })
     }
 
@@ -273,6 +286,7 @@ impl Config {
             max_tokens: self.max_tokens,
             prompt_cache_ttl: self.prompt_cache_ttl,
             show_thinking: self.show_thinking,
+            theme_name: self.theme_name.clone(),
         }
     }
 }
@@ -461,6 +475,23 @@ mod tests {
         assert_eq!(config.prompt_cache_ttl, PromptCacheTtl::OneHour);
         assert!(!config.show_thinking);
         assert!(matches!(config.auth, Auth::ApiKey(k) if k == "sk-default"));
+        assert_eq!(config.theme_name, DEFAULT_THEME);
+    }
+
+    #[tokio::test]
+    async fn load_theme_name_reflects_user_picked_base() {
+        let dir = tempfile::tempdir().unwrap();
+        write_user_config(
+            dir.path(),
+            indoc::indoc! {r#"
+                [tui.theme]
+                base = "latte"
+            "#},
+        );
+        let config = temp_env::async_with_vars(env_vars(vec![xdg(&dir)]), Config::load())
+            .await
+            .unwrap();
+        assert_eq!(config.theme_name, "latte");
     }
 
     #[tokio::test]
@@ -679,7 +710,7 @@ mod tests {
 
     #[tokio::test]
     async fn load_effort_clamps_xhigh_down_to_high_on_sonnet_4_6() {
-        // Sonnet 4.6 has effort but not `xhigh` / `max`; must clamp, not 400 the gateway.
+        // Sonnet 4.6 has effort but caps below `xhigh`; clamping keeps the request from 400ing.
         let dir = tempfile::tempdir().unwrap();
         let vars = env_vars(vec![
             xdg(&dir),
@@ -825,6 +856,7 @@ mod tests {
             thinking: None,
             show_thinking: true,
             theme: Theme::default(),
+            theme_name: "macchiato".to_owned(),
         };
         let snap = cfg.snapshot();
         assert_eq!(snap.auth_label, "OAuth");
@@ -834,6 +866,7 @@ mod tests {
         assert_eq!(snap.max_tokens, 64_000);
         assert_eq!(snap.prompt_cache_ttl, PromptCacheTtl::FiveMin);
         assert!(snap.show_thinking);
+        assert_eq!(snap.theme_name, "macchiato");
     }
 
     // ── display_effort ──

crates/oxide-code/src/main.rs

@@ -373,7 +373,12 @@ async fn agent_loop_task(
                     }
                 }
             }
-            UserAction::Cancel | UserAction::ConfirmExit => {}
+            // Cancel / ConfirmExit are no-ops here; PreviewTheme / SwapTheme are TUI-only and
+            // applied client-side in `App::apply_action_locally`.
+            UserAction::Cancel
+            | UserAction::ConfirmExit
+            | UserAction::PreviewTheme { .. }
+            | UserAction::SwapTheme { .. } => {}
             UserAction::Clear => {
                 let outcome =
                     roll_session(&mut session, &store, &file_tracker, client.model()).await;

crates/oxide-code/src/slash.rs

@@ -23,6 +23,7 @@ mod picker;
 mod registry;
 mod status;
 mod status_modal;
+mod theme;
 
 pub(crate) use context::{LiveSessionInfo, SlashContext};
 pub(crate) use matcher::MatchedCommand;
@@ -111,6 +112,7 @@ pub(crate) fn test_session_info() -> LiveSessionInfo {
             max_tokens: 32_000,
             prompt_cache_ttl: PromptCacheTtl::OneHour,
             show_thinking: false,
+            theme_name: "mocha".to_owned(),
         },
     }
 }

crates/oxide-code/src/slash/registry.rs

@@ -9,6 +9,7 @@ use super::help::HelpCmd;
 use super::init::InitCmd;
 use super::model::ModelCmd;
 use super::status::StatusCmd;
+use super::theme::ThemeCmd;
 use crate::agent::event::UserAction;
 
 /// `Done` for client-side work via `ctx`; `Forward` for state-mutating commands.
@@ -58,6 +59,7 @@ pub(crate) trait SlashCommand: Sync {
 /// Alphabetical for stable `/help` and empty-query popup ordering.
 pub(super) const BUILT_INS: &[&dyn SlashCommand] = &[
     &ClearCmd, &ConfigCmd, &DiffCmd, &EffortCmd, &HelpCmd, &InitCmd, &ModelCmd, &StatusCmd,
+    &ThemeCmd,
 ];
 
 /// Resolves `name` against canonical names first, then aliases.