feat(slash): typed-arg autocomplete + always-picker popup + model cleanup

README.md

@@ -20,7 +20,7 @@ Early development. What works today:
 - Agent loop with extended thinking and tool-use round-trip
 - File and search tools: `read`, `write`, `edit`, `glob`, `grep`, `bash`
 - Turn interruption (Esc / Ctrl+C) plus mid-turn queued follow-up prompts that splice into the same turn between tool calls, with double-press Ctrl+C exit confirmation
-- Slash commands with `/`-triggered autocomplete: `/clear`, `/config`, `/diff`, `/effort`, `/help`, `/init`, `/model`, `/status`
+- Slash commands with `/`-triggered autocomplete (name and curated-arg modes): `/clear`, `/config`, `/diff`, `/effort`, `/help`, `/init`, `/model`, `/status`, `/theme`
 - `CLAUDE.md` / `AGENTS.md` instruction-file discovery
 - Session persistence with JSONL conversation logs, listing, and resume
 - Per-session file-change tracking with a Read-before-Edit gate and on-disk drift detection

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

@@ -47,7 +47,7 @@ pub(super) fn compute_betas(
             out.push(CONTEXT_MANAGEMENT_BETA_HEADER);
         }
         out.push(PROMPT_CACHING_SCOPE_BETA_HEADER);
-        if caps.effort {
+        if caps.has_effort() {
             out.push(EFFORT_BETA_HEADER);
         }
     }

crates/oxide-code/src/config.rs

@@ -92,7 +92,7 @@ impl Effort {
     pub(crate) const ALL: [Self; 5] = [Self::Low, Self::Medium, Self::High, Self::Xhigh, Self::Max];
     pub(crate) const VALID_VALUES: &str = "low, medium, high, xhigh, max";
 
-    const fn as_str(self) -> &'static str {
+    pub(crate) const fn as_str(self) -> &'static str {
         match self {
             Self::Low => "low",
             Self::Medium => "medium",
@@ -101,6 +101,17 @@ impl Effort {
             Self::Max => "max",
         }
     }
+
+    /// One-line UX hint for the typed-arg popup.
+    pub(crate) const fn description(self) -> &'static str {
+        match self {
+            Self::Low => "Fastest, shallow reasoning",
+            Self::Medium => "Balanced",
+            Self::High => "Deep reasoning",
+            Self::Xhigh => "Extended thinking",
+            Self::Max => "Maximum thinking",
+        }
+    }
 }
 
 impl fmt::Display for Effort {