feat(attachments): fondation pipeline durable d'attachments agent/chat + sandbox-safe (#154, QA verte)

Socle #154 : entité attachment, store, contrat DTO et routage session. Modules : domain/chat_attachment, application/chat_attachments, infrastructure/chat_attachments, app-tauri (commands/lib), backend dto.

crates/app-tauri/tests/dto_chat.rs

@@ -6,11 +6,14 @@
 //! - non-regression: every `TerminalSessionDto` construction path now serialises a
 //!   `cellKind` and PTY paths keep `"pty"`.
 
-use app_tauri_lib::dto::{CellKind, ReattachChatDto, ReplyChunk, TerminalSessionDto};
+use app_tauri_lib::dto::{
+    CellKind, ChatAttachmentDto, ChatAttachmentInputDto, ImportChatAttachmentsRequestDto,
+    ImportChatAttachmentsResponseDto, ReattachChatDto, ReplyChunk, TerminalSessionDto,
+};
 use application::{LaunchAgentOutput, StructuredSessionDescriptor};
 use domain::project::ProjectPath;
-use domain::SessionId;
 use domain::{AgentId, NodeId, PtySize, SessionKind, SessionStatus, TerminalSession};
+use domain::{ChatAttachmentSourceKind, SessionId};
 use serde_json::json;
 use uuid::Uuid;
 
@@ -103,6 +106,84 @@ fn reply_chunk_rejects_snake_case_tag() {
     assert!(r.is_err(), "snake_case kind must not deserialise");
 }
 
+// ---------------------------------------------------------------------------
+// Chat attachments — structured input + durable metadata, camelCase
+// ---------------------------------------------------------------------------
+
+#[test]
+fn chat_attachment_input_dto_deserialises_camel_case() {
+    let dto: ChatAttachmentInputDto = serde_json::from_value(json!({
+        "path": "/tmp/picked.png",
+        "mime": "image/png",
+        "sourceKind": "clipboard"
+    }))
+    .unwrap();
+
+    assert_eq!(dto.path, "/tmp/picked.png");
+    assert_eq!(dto.mime.as_deref(), Some("image/png"));
+    assert_eq!(dto.source_kind, Some(ChatAttachmentSourceKind::Clipboard));
+}
+
+#[test]
+fn chat_attachment_dto_serialises_camel_case() {
+    let dto = ChatAttachmentDto {
+        id: "attach-1".to_owned(),
+        filename: "picked.png".to_owned(),
+        mime: "image/png".to_owned(),
+        size_bytes: 9,
+        source_kind: ChatAttachmentSourceKind::LocalFile,
+        storage_path: "agent-chat/session/attach-1-picked.png".to_owned(),
+        readable_path: "/project/.ideai/attachments/agent-chat/session/attach-1-picked.png"
+            .to_owned(),
+        created_at: 42,
+    };
+
+    let v = serde_json::to_value(dto).unwrap();
+    assert_eq!(v["sizeBytes"], 9);
+    assert_eq!(v["sourceKind"], "localFile");
+    assert_eq!(v["storagePath"], "agent-chat/session/attach-1-picked.png");
+    assert!(v.get("readable_path").is_none(), "no snake_case leak");
+}
+
+#[test]
+fn import_chat_attachments_request_response_use_camel_case() {
+    let request: ImportChatAttachmentsRequestDto = serde_json::from_value(json!({
+        "sessionId": "sess-1",
+        "attachmentPaths": ["/tmp/legacy.txt"],
+        "attachments": [{
+            "path": "/tmp/picked.png",
+            "mime": "image/png",
+            "sourceKind": "dragDrop"
+        }]
+    }))
+    .unwrap();
+
+    assert_eq!(request.session_id, "sess-1");
+    assert_eq!(request.attachment_paths, vec!["/tmp/legacy.txt"]);
+    assert_eq!(
+        request.attachments[0].source_kind,
+        Some(ChatAttachmentSourceKind::DragDrop)
+    );
+
+    let response = ImportChatAttachmentsResponseDto {
+        attachments: vec![ChatAttachmentDto {
+            id: "attach-1".to_owned(),
+            filename: "picked.png".to_owned(),
+            mime: "image/png".to_owned(),
+            size_bytes: 9,
+            source_kind: ChatAttachmentSourceKind::LocalFile,
+            storage_path: "agent-chat/session/attach-1-picked.png".to_owned(),
+            readable_path: "/project/.ideai/attachments/agent-chat/session/attach-1-picked.png"
+                .to_owned(),
+            created_at: 42,
+        }],
+    };
+    let v = serde_json::to_value(response).unwrap();
+
+    assert_eq!(v["attachments"][0]["sizeBytes"], 9);
+    assert!(v.get("attachment_paths").is_none(), "no snake_case leak");
+}
+
 // ---------------------------------------------------------------------------
 // ReattachChatDto — typed scrollback, camelCase (zone 5)
 // ---------------------------------------------------------------------------