Perfect! All tasks have been completed successfully. Here's a summary of the changes: (#970)

Successfully implemented a better delete task workflow that properly handles task family relationships:

1. **Database Migration** (`crates/db/migrations/20251007000000_set_null_parent_task_attempt_on_delete.sql`):
   - Updated the `parent_task_attempt` foreign key constraint from the default behavior to `ON DELETE SET NULL`
   - This ensures that when a task attempt is deleted, child tasks are decoupled rather than deleted

2. **Backend - Database Layer** (`crates/db/src/models/task.rs`):
   - Added `find_children_by_parent_task_id()` method to find all child tasks created by any attempts of a given parent task

3. **Backend - API Layer** (`crates/server/src/routes/tasks.rs`):
   - Updated `delete_task()` endpoint to check for child tasks before deletion and log them
   - Added `get_task_children()` endpoint to fetch child tasks for a given task
   - Updated analytics to track the number of child tasks affected

4. **Frontend - API Client** (`frontend/src/lib/api.ts`):
   - Added `getChildren()` method to fetch child tasks for a given task

5. **Frontend - UI** (`frontend/src/components/dialogs/tasks/DeleteTaskConfirmationDialog.tsx`):
   - Added loading and display of child tasks before deletion
   - Shows a warning with the list of child tasks that will be decoupled
   - Displays up to 3 child task names with a count of remaining ones

6. **MCP Server** (`crates/server/src/mcp/task_server.rs`):
   - Updated `delete_task` tool description to clarify that child tasks are decoupled, not deleted
   - Updated success message to inform about decoupled children

- When a task is deleted, all its attempts are deleted (CASCADE)
- Child tasks that were created by those attempts have their `parent_task_attempt` set to NULL (decoupled)
- The UI warns users about child tasks that will be affected
- Child tasks remain in the project and can continue to be worked on independently

All code compiles successfully and sqlx queries have been prepared.

crates/db/.sqlx/query-01a0f9724e5fce7d3312a742e72cded85605ee540150972e2a8364919f56d5c0.json

@@ -46,12 +46,12 @@
       {
         "name": "has_in_progress_attempt!: i64",
         "ordinal": 8,
-        "type_info": "Null"
+        "type_info": "Integer"
       },
       {
         "name": "last_attempt_failed!: i64",
         "ordinal": 9,
-        "type_info": "Null"
+        "type_info": "Integer"
       },
       {
         "name": "executor!: String",
@@ -71,8 +71,8 @@
       true,
       false,
       false,
-      null,
-      null,
+      false,
+      false,
       true
     ]
   },

crates/db/migrations/20251007000000_set_null_parent_task_attempt_on_delete.sql

@@ -0,0 +1,32 @@
+PRAGMA foreign_keys = OFF;
+
+-- Create new tasks table with updated foreign key constraint
+CREATE TABLE tasks_new (
+    id          BLOB PRIMARY KEY,
+    project_id  BLOB NOT NULL,
+    title       TEXT NOT NULL,
+    description TEXT,
+    status      TEXT NOT NULL DEFAULT 'todo'
+                   CHECK (status IN ('todo','inprogress','done','cancelled','inreview')),
+    parent_task_attempt BLOB,
+    created_at  TEXT NOT NULL DEFAULT (datetime('now', 'subsec')),
+    updated_at  TEXT NOT NULL DEFAULT (datetime('now', 'subsec')),
+    FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE,
+    FOREIGN KEY (parent_task_attempt) REFERENCES task_attempts(id) ON DELETE SET NULL
+);
+
+-- Copy data from old table to new table
+INSERT INTO tasks_new (id, project_id, title, description, status, parent_task_attempt, created_at, updated_at)
+SELECT id, project_id, title, description, status, parent_task_attempt, created_at, updated_at
+FROM tasks;
+
+-- Drop old table
+DROP TABLE tasks;
+
+-- Rename new table to original name
+ALTER TABLE tasks_new RENAME TO tasks;
+
+-- Recreate index for parent_task_attempt lookups
+CREATE INDEX idx_tasks_parent_task_attempt ON tasks(parent_task_attempt);
+
+PRAGMA foreign_keys = ON;