feat: implémentation et QA ticket99 - agent model configuration v2

- backend A-C: VO Codex/Claude, renderers/projecteurs modèle, SecretRef/env, catalogues/use cases/Tauri commands
- frontend D: profils Codex/Claude provider->model->secret, validations, conservation SecretRef
- fix: app-tauri embedded_server isolant IDEA_WEB_ROOT

QA: backend 57/57 tests, frontend 74/74 tests OK

crates/infrastructure/src/permission/claude.rs

@@ -34,11 +34,12 @@ impl PermissionProjector for ClaudePermissionProjector {
         _network: Option<domain::NetworkPolicy>,
         ctx: &ProjectionContext,
     ) -> PermissionProjection {
-        // Product invariant: nothing posed ⇒ nothing projected (native prompting).
-        let Some(_) = eff else {
+        // Product invariant: no permissions and no model ⇒ nothing projected
+        // (native prompting). A model is orthogonal and still gets materialised.
+        if eff.is_none() && ctx.model.is_none() {
             return PermissionProjection::empty();
-        };
-        let contents = claude_settings_seed(ctx.project_root, eff);
+        }
+        let contents = claude_settings_seed(ctx.project_root, eff, ctx.model);
         PermissionProjection {
             files: vec![ProjectedFile::Replace {
                 rel_path: SETTINGS_REL_PATH.to_owned(),
@@ -57,7 +58,22 @@ impl PermissionProjector for ClaudePermissionProjector {
 /// Builds the Claude Code permission seed. `project_root` is embedded verbatim
 /// (JSON-escaped) and granted as an additional working directory, since the cwd is
 /// the run dir and the agent works on the root above it.
-fn claude_settings_seed(project_root: &str, permissions: Option<&EffectivePermissions>) -> String {
+fn claude_settings_seed(
+    project_root: &str,
+    permissions: Option<&EffectivePermissions>,
+    model: Option<&str>,
+) -> String {
+    let model_line = model
+        .map(|model| format!("  \"model\": {},\n", json_literal(model)))
+        .unwrap_or_default();
+    if permissions.is_none() {
+        return format!(
+            r#"{{
+{model_line}  "enabledMcpjsonServers": ["idea"]
+}}
+"#
+        );
+    }
     let root = json_escape(project_root);
     let default_mode = match permissions.map(EffectivePermissions::fallback) {
         Some(Posture::Deny) => "plan",
@@ -80,7 +96,7 @@ fn claude_settings_seed(project_root: &str, permissions: Option<&EffectivePermis
     let deny = json_string_array(&merge_default_deny(deny));
     format!(
         r#"{{
-  "permissions": {{
+{model_line}  "permissions": {{
     "defaultMode": "{default_mode}",
     "additionalDirectories": [
       "{root}"
@@ -197,6 +213,10 @@ fn json_string_array(items: &[String]) -> String {
     format!("[\n{body}\n    ]")
 }
 
+fn json_literal(value: &str) -> String {
+    format!("\"{}\"", json_escape(value))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -207,6 +227,10 @@ mod tests {
         ProjectionContext {
             project_root: root,
             run_dir,
+            model: None,
+            model_provider: None,
+            model_provider_base_url: None,
+            model_provider_env_key: None,
         }
     }
 
@@ -255,6 +279,31 @@ mod tests {
         assert!(proj.env.is_empty());
     }
 
+    #[test]
+    fn model_projects_even_without_permissions() {
+        let ctx = ProjectionContext {
+            project_root: "/proj",
+            run_dir: "/run",
+            model: Some("claude-sonnet-4-5"),
+            model_provider: None,
+            model_provider_base_url: None,
+            model_provider_env_key: None,
+        };
+        let proj = ClaudePermissionProjector.project(None, None, &ctx);
+        assert!(proj.args.is_empty());
+        assert!(proj.env.is_empty());
+        assert_eq!(proj.files.len(), 1);
+        match &proj.files[0] {
+            ProjectedFile::Replace { rel_path, contents } => {
+                assert_eq!(rel_path, SETTINGS_REL_PATH);
+                let json: Value = serde_json::from_str(contents).unwrap();
+                assert_eq!(json["model"], "claude-sonnet-4-5");
+                assert!(json.get("permissions").is_none());
+            }
+            ProjectedFile::MergeToml { .. } => panic!("Claude must emit a Replace file"),
+        }
+    }
+
     #[test]
     fn owned_replace_paths_is_the_settings_file() {
         assert_eq!(