fix: livrable tickets #70 #100 #102 — UX surface scoping

- #70: implémentation suppression modèles locaux téléchargés
- #100: correction scroll OpenCode
- #102: correction fit TUI après switch/layout
- memory note scoping UX

crates/domain/src/ports.rs

@@ -1311,6 +1311,22 @@ pub struct ModelArtifactResolution {
     pub cache_hit: bool,
 }
 
+/// Cache state for a model artifact managed by IdeA.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ModelArtifactState {
+    /// Artifact source is not managed by the downloader.
+    NotManaged,
+    /// Managed artifact is not present in cache.
+    Missing,
+    /// Managed artifact is present in cache.
+    Downloaded {
+        /// Local path used to launch the model.
+        path: ModelPath,
+        /// Total on-disk bytes when known.
+        size_bytes: Option<u64>,
+    },
+}
+
 /// Cooperative cancellation token for model artifact resolution.
 #[derive(Debug, Clone, Default)]
 pub struct ModelArtifactCancel {
@@ -1339,6 +1355,15 @@ impl ModelArtifactCancel {
 /// Resolves or downloads a model artifact before starting a model server.
 #[async_trait]
 pub trait ModelArtifactDownloader: Send + Sync {
+    /// Returns the current cache state for a Hugging Face model reference.
+    ///
+    /// # Errors
+    /// [`ModelServerError`] when the cache cannot be inspected.
+    async fn hf_model_state(
+        &self,
+        repo: &HfModelRef,
+    ) -> Result<ModelArtifactState, ModelServerError>;
+
     /// Resolves a Hugging Face model to a local artifact path.
     ///
     /// # Errors
@@ -1349,6 +1374,14 @@ pub trait ModelArtifactDownloader: Send + Sync {
         progress: Arc<dyn Fn(ModelArtifactProgress) + Send + Sync>,
         cancel: ModelArtifactCancel,
     ) -> Result<ModelArtifactResolution, ModelServerError>;
+
+    /// Deletes the cached artifact for a Hugging Face model reference.
+    ///
+    /// Deleting a missing artifact is a successful no-op.
+    ///
+    /// # Errors
+    /// [`ModelServerError`] when deletion fails.
+    async fn delete_hf_model(&self, repo: &HfModelRef) -> Result<(), ModelServerError>;
 }
 
 /// Manages local long-lived child processes.