From 12f7d2b484ccee64caf2855cb5f9ed79f2497c8d Mon Sep 17 00:00:00 2001
From: diegosouzapw <diegosouzapw@users.noreply.github.com>
Date: Sat, 28 Feb 2026 00:54:07 -0300
Subject: [PATCH] fix: preserve database data on upgrade when old
 schema_migrations exists (#146)

Previously, the upgrade detection logic renamed the entire DB file when it
found a schema_migrations table (from older versions), causing data loss.
Now checks if the DB actually contains data (provider_connections) before
deciding to rename. If data exists, drops only the old migration tracking
table and lets the new CREATE TABLE IF NOT EXISTS schema take over.
---
 src/lib/db/core.ts | 52 ++++++++++++++++++++++++++++++++++++----------
 1 file changed, 41 insertions(+), 11 deletions(-)

diff --git a/src/lib/db/core.ts b/src/lib/db/core.ts
index 10c133db42..a9d2a5de64 100644
--- a/src/lib/db/core.ts
+++ b/src/lib/db/core.ts
@@ -322,28 +322,58 @@ export function getDbInstance() {
     return _db;
   }
 
-  // Detect and replace old incompatible schema
+  // Detect and handle old schema format — preserve data when possible (#146)
   if (fs.existsSync(SQLITE_FILE)) {
     try {
       const probe = new Database(SQLITE_FILE, { readonly: true });
       const hasOldSchema = probe
         .prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='schema_migrations'")
         .get();
-      probe.close();
 
       if (hasOldSchema) {
-        const oldPath = SQLITE_FILE + ".old-schema";
-        console.log(
-          `[DB] Old incompatible schema detected — renaming to ${path.basename(oldPath)}`
-        );
-        fs.renameSync(SQLITE_FILE, oldPath);
-        for (const ext of ["-wal", "-shm"]) {
+        // Check if the DB has actual data we should preserve
+        let hasData = false;
+        try {
+          const count = probe.prepare("SELECT COUNT(*) as c FROM provider_connections").get();
+          hasData = count && count.c > 0;
+        } catch {
+          // Table might not exist at all — truly incompatible
+        }
+        probe.close();
+
+        if (hasData) {
+          // Data exists — preserve it! Just drop the old migration tracking table
+          // and let our new migration system (CREATE TABLE IF NOT EXISTS) take over
+          console.log(
+            `[DB] Old schema_migrations table found but data exists — preserving data (#146)`
+          );
+          const fixDb = new Database(SQLITE_FILE);
           try {
-            if (fs.existsSync(SQLITE_FILE + ext)) fs.unlinkSync(SQLITE_FILE + ext);
-          } catch {
-            /* ok */
+            fixDb.exec("DROP TABLE IF EXISTS schema_migrations");
+            // Clean up WAL/SHM files that might be stale
+            fixDb.pragma("wal_checkpoint(TRUNCATE)");
+          } catch (e) {
+            console.warn("[DB] Could not clean up old schema table:", e.message);
+          } finally {
+            fixDb.close();
+          }
+        } else {
+          // No data — safe to rename and start fresh
+          const oldPath = SQLITE_FILE + ".old-schema";
+          console.log(
+            `[DB] Old incompatible schema detected (empty) — renaming to ${path.basename(oldPath)}`
+          );
+          fs.renameSync(SQLITE_FILE, oldPath);
+          for (const ext of ["-wal", "-shm"]) {
+            try {
+              if (fs.existsSync(SQLITE_FILE + ext)) fs.unlinkSync(SQLITE_FILE + ext);
+            } catch {
+              /* ok */
+            }
           }
         }
+      } else {
+        probe.close();
       }
     } catch (e) {
       console.warn("[DB] Could not probe existing DB, will create fresh:", e.message);