fix(chat): restaure le collage des images dans le composer custom CLI (#184)

Le collage d'une image (ex. capture d'écran) échouait en environnement desktop : le presse-papier image n'est souvent pas exposé comme un File synchrone dans clipboardData.files, mais uniquement via l'Async Clipboard API. On ajoute donc un repli sur navigator.clipboard.read() (MIME image/*) quand l'événement de collage ne fournit aucun fichier. Le preventDefault() n'est émis que lorsqu'on a effectivement lu des fichiers issus de l'événement, afin de ne pas bloquer le collage texte quand le repli async ne remonte rien.

- refactor clipboardFiles(event) -> dataTransferFiles(DataTransfer) réutilisable
- dedupeKey robuste pour les images sans nom (mime + taille + contenu base64)
- ReplyChunk::UserPrompt porte désormais les labels d'attachments (DTO + accounting reply_chunk_bytes, skip_serializing_if Vec::is_empty)
- tests ciblés frontend (+219) et backend (chat_bridge/dto/attachments) verts

QA : tests ciblés verts. Réserve : environnement headless, pas de validation manuelle desktop — validation AppImage à confirmer en suivi.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/app-tauri/src/chat.rs

@@ -145,7 +145,9 @@ impl ChatBridge {
 
 fn reply_chunk_bytes(chunk: &ReplyChunk) -> usize {
     match chunk {
-        ReplyChunk::UserPrompt { text } => text.len(),
+        ReplyChunk::UserPrompt { text, attachments } => {
+            text.len() + attachments.iter().map(String::len).sum::<usize>()
+        }
         ReplyChunk::TextDelta { text } => text.len(),
         ReplyChunk::ToolActivity { label } => label.len(),
         ReplyChunk::Progress { progress } => {

crates/app-tauri/src/commands.rs

@@ -2356,6 +2356,10 @@ pub async fn agent_send(
     )
     .await?;
     let prompt_for_model = prompt_with_imported_attachments(&prompt, &imported_attachments);
+    let attachment_labels = imported_attachments
+        .iter()
+        .map(|attachment| attachment.filename.clone())
+        .collect();
 
     // Retain the human submit in the same live scrollback as model chunks so
     // `reattach_agent_chat` can repaint the whole in-flight conversation.
@@ -2363,6 +2367,7 @@ pub async fn agent_send(
         &sid,
         ReplyChunk::UserPrompt {
             text: prompt.clone(),
+            attachments: attachment_labels,
         },
     );
 

crates/app-tauri/tests/chat_bridge.rs

@@ -61,7 +61,9 @@ fn error_chunk(s: &str) -> ReplyChunk {
 
 fn chunk_bytes(chunk: &ReplyChunk) -> usize {
     match chunk {
-        ReplyChunk::UserPrompt { text } => text.len(),
+        ReplyChunk::UserPrompt { text, attachments } => {
+            text.len() + attachments.iter().map(String::len).sum::<usize>()
+        }
         ReplyChunk::TextDelta { text } => text.len(),
         ReplyChunk::ToolActivity { label } => label.len(),
         ReplyChunk::Progress { progress } => {

crates/app-tauri/tests/dto_chat.rs

@@ -27,11 +27,29 @@ use uuid::Uuid;
 fn reply_chunk_user_prompt_serialises_exact_camel_case() {
     let v = serde_json::to_value(ReplyChunk::UserPrompt {
         text: "run tests".into(),
+        attachments: Vec::new(),
     })
     .unwrap();
     assert_eq!(v, json!({ "kind": "userPrompt", "text": "run tests" }));
 }
 
+#[test]
+fn reply_chunk_user_prompt_serialises_attachment_labels() {
+    let v = serde_json::to_value(ReplyChunk::UserPrompt {
+        text: "describe this".into(),
+        attachments: vec!["clipboard.png".into()],
+    })
+    .unwrap();
+    assert_eq!(
+        v,
+        json!({
+            "kind": "userPrompt",
+            "text": "describe this",
+            "attachments": ["clipboard.png"]
+        })
+    );
+}
+
 #[test]
 fn reply_chunk_text_delta_serialises_exact_camel_case() {
     let v = serde_json::to_value(ReplyChunk::TextDelta {
@@ -105,7 +123,10 @@ fn reply_chunk_error_serialises_exact_camel_case() {
 #[test]
 fn reply_chunk_round_trips_through_json_for_every_variant() {
     for chunk in [
-        ReplyChunk::UserPrompt { text: "u".into() },
+        ReplyChunk::UserPrompt {
+            text: "u".into(),
+            attachments: vec!["clipboard.png".into()],
+        },
         ReplyChunk::TextDelta { text: "x".into() },
         ReplyChunk::ToolActivity {
             label: "runs".into(),
@@ -140,7 +161,13 @@ fn reply_chunk_deserialises_from_camel_case_wire_payload() {
     // The shape the frontend (or a mock gateway) emits.
     let back: ReplyChunk =
         serde_json::from_value(json!({ "kind": "userPrompt", "text": "hi" })).unwrap();
-    assert_eq!(back, ReplyChunk::UserPrompt { text: "hi".into() });
+    assert_eq!(
+        back,
+        ReplyChunk::UserPrompt {
+            text: "hi".into(),
+            attachments: Vec::new()
+        }
+    );
 }
 
 #[test]
@@ -310,7 +337,10 @@ fn reattach_chat_dto_serialises_camel_case_with_typed_scrollback() {
     let dto = ReattachChatDto {
         session_id: "sess-1".into(),
         scrollback: vec![
-            ReplyChunk::UserPrompt { text: "Hi".into() },
+            ReplyChunk::UserPrompt {
+                text: "Hi".into(),
+                attachments: Vec::new(),
+            },
             ReplyChunk::TextDelta { text: "Hi".into() },
             ReplyChunk::Final {
                 content: "Hi".into(),

crates/application/tests/chat_attachments.rs

@@ -318,7 +318,9 @@ async fn import_chat_attachments_rejects_empty_clipboard_bytes_before_store_call
         .unwrap_err();
 
     assert_eq!(err.code(), "INVALID");
-    assert!(err.to_string().contains("chat attachment must not be empty"));
+    assert!(err
+        .to_string()
+        .contains("chat attachment must not be empty"));
     assert!(store.path_calls.lock().unwrap().is_empty());
     assert!(store.bytes_calls.lock().unwrap().is_empty());
 }

crates/backend/src/dto.rs

@@ -3347,6 +3347,9 @@ pub enum ReplyChunk {
     UserPrompt {
         /// Submitted prompt text.
         text: String,
+        /// Display labels for attachments submitted with the prompt.
+        #[serde(default, skip_serializing_if = "Vec::is_empty")]
+        attachments: Vec<String>,
     },
     /// An assistant text fragment (incremental chat rendering).
     #[serde(rename_all = "camelCase")]