feat(model-picker): each row names its connected provider

The shell stamps meta.provider (platform display name via
parse_managed_model_key) on every managed {platform}/{model} catalog
entry in to_acp_model_info; user-defined [model.*] entries stay
provider-less. The /model dropdown surfaces it in the description column
(a model's own description still wins), so the picker reads as 'choose a
model from your connected providers'.

Verified: kigi-shell 5261 + kigi-tui 6873 tests green, clippy clean.

crates/codegen/kigi-shell/src/agent/config.rs

@@ -4229,6 +4229,21 @@ pub fn to_acp_model_info(
                     "agentType".to_string(),
                     serde_json::Value::String(info.agent_type.clone()),
                 );
+                // Provider display name for managed `{platform}/{model}`
+                // entries — lets the client's model picker say which
+                // connected provider each model belongs to. Absent for
+                // user-defined `[model.*]` entries (no known platform).
+                if let Some((platform, _)) = info
+                    .id
+                    .as_deref()
+                    .or(Some(key.as_str()))
+                    .and_then(kigi_models::parse_managed_model_key)
+                {
+                    map.insert(
+                        "provider".to_string(),
+                        serde_json::Value::String(platform.display_name().to_string()),
+                    );
+                }
                 if info.supports_reasoning_effort {
                     map.insert(
                         "supportsReasoningEffort".to_string(),
@@ -5925,6 +5940,49 @@ reasoning_effort = "low"
             "agentType should always be in meta, defaulting to DEFAULT_AGENT_TYPE"
         );
     }
+    /// Managed `{platform}/{model}` entries stamp `meta.provider` with the
+    /// platform's display name so the client's model picker can say which
+    /// connected provider each model belongs to. User-defined `[model.*]`
+    /// entries (no known platform prefix) stay provider-less.
+    #[test]
+    fn acp_model_meta_stamps_provider_for_managed_entries() {
+        let mut models = IndexMap::new();
+        let mut managed = test_model_entry(
+            "claude-opus-4-8",
+            "https://api.anthropic.com/v1",
+            None,
+            None,
+            None,
+        );
+        managed.info.id = Some("claude-pro-max/claude-opus-4-8".to_string());
+        models.insert("claude-pro-max/claude-opus-4-8".to_string(), managed);
+        models.insert(
+            "my-custom".to_string(),
+            test_model_entry("my-custom", "https://test.api/v1", None, None, None),
+        );
+
+        let acp_models = to_acp_model_info(&models);
+        let claude = acp_models
+            .get(&acp::ModelId::new(Arc::from(
+                "claude-pro-max/claude-opus-4-8",
+            )))
+            .unwrap();
+        assert_eq!(
+            claude.meta.as_ref().unwrap()["provider"],
+            kigi_models::PlatformId::ClaudeProMax.display_name(),
+        );
+        let custom = acp_models
+            .get(&acp::ModelId::new(Arc::from("my-custom")))
+            .unwrap();
+        assert!(
+            custom
+                .meta
+                .as_ref()
+                .is_none_or(|m| m.get("provider").is_none()),
+            "a user-defined entry carries no provider"
+        );
+    }
+
     #[test]
     fn acp_model_meta_emits_reasoning_effort_when_supported() {
         let mut models = IndexMap::new();

crates/codegen/kigi-tui/src/slash/commands/model.rs

@@ -150,6 +150,9 @@ fn detect_effort_phase(models: &ModelState, args_query: &str) -> Option<acp::Mod
 
 /// One row per logical model. Reasoning models get a trailing space in
 /// `insert_text` so the prompt widget chains into the effort sub-menu.
+/// The description column names the model's provider (shell-stamped
+/// `meta.provider` — the connected platform the model was fetched from)
+/// when the model carries no description of its own.
 fn build_model_items(models: &ModelState) -> Vec<ArgItem> {
     let current_id = models.current.as_ref();
     let mut items: Vec<ArgItem> = Vec::with_capacity(models.available.len());
@@ -172,11 +175,22 @@ fn build_model_items(models: &ModelState) -> Vec<ArgItem> {
             info.name.clone()
         };
 
+        let provider = info
+            .meta
+            .as_ref()
+            .and_then(|m| m.get("provider"))
+            .and_then(|v| v.as_str());
+        let description = match (info.description.as_deref(), provider) {
+            (Some(d), _) if !d.is_empty() => d.to_string(),
+            (_, Some(p)) => p.to_string(),
+            _ => String::new(),
+        };
+
         items.push(ArgItem {
             display,
             match_text: info.name.clone(),
             insert_text,
-            description: info.description.clone().unwrap_or_default(),
+            description,
         });
     }
     items
@@ -294,6 +308,37 @@ mod tests {
         assert_eq!(plain.insert_text, "Kigi 4.5");
     }
 
+    /// Rows for shell-managed platform models show their provider (stamped
+    /// `meta.provider`) in the description column, so the picker says which
+    /// connected provider each model belongs to. A model's own description
+    /// wins when present; entries without provider meta stay blank.
+    #[test]
+    fn model_rows_show_provider_in_description() {
+        let mut state = ModelState::default();
+
+        let claude_id = acp::ModelId::new(Arc::from("claude-pro-max/claude-opus-4-8"));
+        let mut meta = serde_json::Map::new();
+        meta.insert(
+            "provider".into(),
+            serde_json::Value::String("Claude Pro/Max".into()),
+        );
+        let claude =
+            acp::ModelInfo::new(claude_id.clone(), "Claude Opus 4.8".to_string()).meta(Some(meta));
+        state.available.insert(claude_id, claude);
+
+        let (plain_id, plain_info) = plain_model("my-custom", "My Custom");
+        state.available.insert(plain_id, plain_info);
+
+        let items = build_model_items(&state);
+        let claude_row = items
+            .iter()
+            .find(|i| i.match_text == "Claude Opus 4.8")
+            .unwrap();
+        assert_eq!(claude_row.description, "Claude Pro/Max");
+        let plain_row = items.iter().find(|i| i.match_text == "My Custom").unwrap();
+        assert_eq!(plain_row.description, "");
+    }
+
     #[test]
     fn trailing_space_after_reasoning_model_enters_effort_phase() {
         let mut state = ModelState::default();