feat(chat): two-way composer draft sync across desktop and mobile

src-tauri/src/commands/conversations.rs

@@ -3,7 +3,10 @@ use std::collections::{HashMap, HashSet};
 use crate::app_error::AppCommandError;
 use crate::db::entities::conversation;
 use crate::db::entities::folder::FolderKind;
-use crate::db::service::{conversation_service, folder_service, import_service, tab_service};
+use crate::db::service::{
+    conversation_composer_draft_service, conversation_service, folder_service, import_service,
+    tab_service,
+};
 #[cfg(feature = "tauri-runtime")]
 use crate::db::AppDatabase;
 use crate::models::*;
@@ -26,9 +29,10 @@ use crate::parsers::{
     ParseError,
 };
 use crate::web::event_bridge::{
-    emit_event, ConversationChange, ConversationsBulkChanged, EventEmitter, ImportScanProgress,
-    TabsChanged, CONVERSATIONS_BULK_CHANGED_EVENT, CONVERSATION_CHANGED_EVENT,
-    IMPORT_SCAN_PROGRESS_EVENT, TABS_CHANGED_EVENT,
+    emit_event, ComposerDraftChanged, ConversationChange, ConversationsBulkChanged, EventEmitter,
+    ImportScanProgress, TabsChanged, COMPOSER_DRAFT_CHANGED_EVENT,
+    CONVERSATIONS_BULK_CHANGED_EVENT, CONVERSATION_CHANGED_EVENT, IMPORT_SCAN_PROGRESS_EVENT,
+    TABS_CHANGED_EVENT,
 };
 
 pub async fn list_all_conversations_core(
@@ -2000,6 +2004,70 @@ pub async fn update_conversation_pinned(
     Ok(())
 }
 
+/// Fetch the unsent composer text for a persisted conversation. `None` when
+/// no client has saved a draft yet. The body is only returned here — the
+/// WS notify never carries it.
+pub async fn get_composer_draft_core(
+    conn: &sea_orm::DatabaseConnection,
+    conversation_id: i32,
+) -> Result<Option<conversation_composer_draft_service::ComposerDraft>, AppCommandError> {
+    conversation_composer_draft_service::get(conn, conversation_id)
+        .await
+        .map_err(AppCommandError::from)
+}
+
+#[cfg(feature = "tauri-runtime")]
+#[cfg_attr(feature = "tauri-runtime", tauri::command)]
+pub async fn get_composer_draft(
+    db: tauri::State<'_, AppDatabase>,
+    conversation_id: i32,
+) -> Result<Option<conversation_composer_draft_service::ComposerDraft>, AppCommandError> {
+    get_composer_draft_core(&db.conn, conversation_id).await
+}
+
+/// Last-write-wins save of unsent composer text. Broadcasts
+/// [`COMPOSER_DRAFT_CHANGED_EVENT`] with ids only (no body).
+pub async fn put_composer_draft_core(
+    conn: &sea_orm::DatabaseConnection,
+    emitter: &EventEmitter,
+    conversation_id: i32,
+    text: String,
+    origin: String,
+) -> Result<conversation_composer_draft_service::ComposerDraftPutResult, AppCommandError> {
+    let result =
+        conversation_composer_draft_service::put(conn, conversation_id, text, origin).await?;
+    emit_event(
+        emitter,
+        COMPOSER_DRAFT_CHANGED_EVENT,
+        ComposerDraftChanged {
+            conversation_id: result.conversation_id,
+            revision: result.revision,
+            origin: result.origin.clone(),
+            cleared: result.cleared,
+        },
+    );
+    Ok(result)
+}
+
+#[cfg(feature = "tauri-runtime")]
+#[cfg_attr(feature = "tauri-runtime", tauri::command)]
+pub async fn put_composer_draft(
+    app: tauri::AppHandle,
+    db: tauri::State<'_, AppDatabase>,
+    conversation_id: i32,
+    text: String,
+    origin: String,
+) -> Result<conversation_composer_draft_service::ComposerDraftPutResult, AppCommandError> {
+    put_composer_draft_core(
+        &db.conn,
+        &EventEmitter::Tauri(app),
+        conversation_id,
+        text,
+        origin,
+    )
+    .await
+}
+
 pub async fn delete_conversation_core(
     conn: &sea_orm::DatabaseConnection,
     conversation_id: i32,

src-tauri/src/db/entities/conversation_composer_draft.rs

@@ -0,0 +1,19 @@
+use sea_orm::entity::prelude::*;
+
+/// Per-conversation unsent composer text, shared across desktop / web / mobile.
+/// See `crate::db::service::conversation_composer_draft_service`.
+#[derive(Clone, Debug, PartialEq, DeriveEntityModel)]
+#[sea_orm(table_name = "conversation_composer_draft")]
+pub struct Model {
+    #[sea_orm(primary_key, auto_increment = false)]
+    pub conversation_id: i32,
+    pub text: String,
+    pub revision: i64,
+    pub origin: String,
+    pub updated_at: DateTimeUtc,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {}
+
+impl ActiveModelBehavior for ActiveModel {}

src-tauri/src/db/entities/mod.rs

@@ -7,6 +7,7 @@ pub mod chat_channel_message_log;
 pub mod chat_channel_sender_context;
 pub mod chat_channel_thread_binding;
 pub mod conversation;
+pub mod conversation_composer_draft;
 pub mod custom_agent;
 pub mod folder;
 pub mod folder_command;

src-tauri/src/db/migration/m20260815_000002_conversation_composer_draft.rs

@@ -0,0 +1,64 @@
+use sea_orm_migration::prelude::*;
+
+#[derive(DeriveMigrationName)]
+pub struct Migration;
+
+#[async_trait::async_trait]
+impl MigrationTrait for Migration {
+    async fn up(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .create_table(
+                Table::create()
+                    .table(ConversationComposerDraft::Table)
+                    .if_not_exists()
+                    .col(
+                        ColumnDef::new(ConversationComposerDraft::ConversationId)
+                            .integer()
+                            .not_null()
+                            .primary_key(),
+                    )
+                    .col(
+                        ColumnDef::new(ConversationComposerDraft::Text)
+                            .text()
+                            .not_null(),
+                    )
+                    .col(
+                        ColumnDef::new(ConversationComposerDraft::Revision)
+                            .big_integer()
+                            .not_null(),
+                    )
+                    .col(
+                        ColumnDef::new(ConversationComposerDraft::Origin)
+                            .string()
+                            .not_null(),
+                    )
+                    .col(
+                        ColumnDef::new(ConversationComposerDraft::UpdatedAt)
+                            .timestamp_with_time_zone()
+                            .not_null(),
+                    )
+                    .to_owned(),
+            )
+            .await
+    }
+
+    async fn down(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .drop_table(
+                Table::drop()
+                    .table(ConversationComposerDraft::Table)
+                    .to_owned(),
+            )
+            .await
+    }
+}
+
+#[derive(DeriveIden)]
+enum ConversationComposerDraft {
+    Table,
+    ConversationId,
+    Text,
+    Revision,
+    Origin,
+    UpdatedAt,
+}

src-tauri/src/db/migration/mod.rs

@@ -37,6 +37,7 @@ mod m20260803_000001_folder_link;
 mod m20260803_000001_token_usage;
 mod m20260807_000001_work_task_scheduled_at;
 mod m20260808_000001_custom_agent_supports_mcp;
+mod m20260815_000002_conversation_composer_draft;
 pub struct Migrator;
 
 #[async_trait::async_trait]
@@ -80,6 +81,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260803_000001_token_usage::Migration),
             Box::new(m20260807_000001_work_task_scheduled_at::Migration),
             Box::new(m20260808_000001_custom_agent_supports_mcp::Migration),
+            Box::new(m20260815_000002_conversation_composer_draft::Migration),
         ]
     }
 }