Fix migration repair: update checksums instead of deleting records

The previous approach deleted migration records to force re-application,
but this is dangerous for migration 2 which DELETEs all categories and
keywords before re-inserting them, wiping user customizations.

Now computes the expected SHA-384 checksum (matching sqlx) and updates
the stored checksum in _sqlx_migrations, so the migration is recognized
as already applied without being re-run.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/src/commands/profile_commands.rs

@@ -1,6 +1,6 @@
 use rand::RngCore;
 use serde::{Deserialize, Serialize};
-use sha2::{Digest, Sha256};
+use sha2::{Digest, Sha256, Sha384};
 use std::fs;
 use tauri::Manager;
 
@@ -157,8 +157,8 @@ fn hex_encode(bytes: &[u8]) -> String {
 }
 
 /// Repair migration checksums for a profile database.
-/// Deletes migration records that have mismatched checksums so they can be re-applied.
-/// This fixes the "migration X was previously applied but has been modified" error.
+/// Updates stored checksums to match current migration SQL, avoiding re-application
+/// of destructive migrations (e.g., migration 2 which DELETEs categories/keywords).
 #[tauri::command]
 pub fn repair_migrations(app: tauri::AppHandle, db_filename: String) -> Result<bool, String> {
     let app_dir = app
@@ -174,7 +174,6 @@ pub fn repair_migrations(app: tauri::AppHandle, db_filename: String) -> Result<b
     let conn = rusqlite::Connection::open(&db_path)
         .map_err(|e| format!("Cannot open database: {}", e))?;
 
-    // Check if _sqlx_migrations table exists
     let table_exists: bool = conn
         .query_row(
             "SELECT COUNT(*) > 0 FROM sqlite_master WHERE type='table' AND name='_sqlx_migrations'",
@@ -187,14 +186,34 @@ pub fn repair_migrations(app: tauri::AppHandle, db_filename: String) -> Result<b
         return Ok(false);
     }
 
-    // Delete migration 1 record so it can be cleanly re-applied
-    // Migration 1 is idempotent (CREATE IF NOT EXISTS + INSERT OR IGNORE)
-    let deleted = conn
-        .execute(
-            "DELETE FROM _sqlx_migrations WHERE version = 1",
-            [],
-        )
-        .map_err(|e| format!("Cannot repair migrations: {}", e))?;
+    // Current migration SQL — must match the vec in lib.rs
+    let migrations: &[(i64, &str)] = &[
+        (1, database::SCHEMA),
+        (2, database::SEED_CATEGORIES),
+    ];
 
-    Ok(deleted > 0)
+    let mut repaired = false;
+    for (version, sql) in migrations {
+        let expected_checksum = Sha384::digest(sql.as_bytes()).to_vec();
+
+        // Check if this migration exists with a different checksum
+        let needs_repair: bool = conn
+            .query_row(
+                "SELECT COUNT(*) > 0 FROM _sqlx_migrations WHERE version = ?1 AND checksum != ?2",
+                rusqlite::params![version, expected_checksum],
+                |row| row.get(0),
+            )
+            .unwrap_or(false);
+
+        if needs_repair {
+            conn.execute(
+                "UPDATE _sqlx_migrations SET checksum = ?1 WHERE version = ?2",
+                rusqlite::params![expected_checksum, version],
+            )
+            .map_err(|e| format!("Cannot repair migration {}: {}", version, e))?;
+            repaired = true;
+        }
+    }
+
+    Ok(repaired)
 }