fix(config-migration): always apply migration in-memory and track backup success

Migration changes were only applied to rawConfig if file write succeeded,
leaving the running process on stale config. Also stops logging backup
path when the backup copy itself failed.

src/shared/migration/config-migration.ts

@@ -8,7 +8,6 @@ export function migrateConfigFile(
   configPath: string,
   rawConfig: Record<string, unknown>
 ): boolean {
-  // Work on a deep copy — only apply changes to rawConfig if file write succeeds
   const copy = structuredClone(rawConfig)
   let needsWrite = false
 
@@ -98,28 +97,36 @@ export function migrateConfigFile(
   }
 
   if (needsWrite) {
+    const timestamp = new Date().toISOString().replace(/[:.]/g, "-")
+    const backupPath = `${configPath}.bak.${timestamp}`
+    let backupSucceeded = false
     try {
-      const timestamp = new Date().toISOString().replace(/[:.]/g, "-")
-      const backupPath = `${configPath}.bak.${timestamp}`
-      try {
-        fs.copyFileSync(configPath, backupPath)
-      } catch {
-        // Original file may not exist yet — skip backup
-      }
-
-      fs.writeFileSync(configPath, JSON.stringify(copy, null, 2) + "\n", "utf-8")
-      log(`Migrated config file: ${configPath} (backup: ${backupPath})`)
-    } catch (err) {
-      log(`Failed to write migrated config to ${configPath}:`, err)
-      // File write failed — rawConfig is untouched, preserving user's original values
-      return false
+      fs.copyFileSync(configPath, backupPath)
+      backupSucceeded = true
+    } catch {
+      // Original file may not exist yet — skip backup
+    }
+
+    let writeSucceeded = false
+    try {
+      fs.writeFileSync(configPath, JSON.stringify(copy, null, 2) + "\n", "utf-8")
+      writeSucceeded = true
+    } catch (err) {
+      log(`Failed to write migrated config to ${configPath}:`, err)
     }
 
-    // File write succeeded — apply changes to the original rawConfig
     for (const key of Object.keys(rawConfig)) {
       delete rawConfig[key]
     }
     Object.assign(rawConfig, copy)
+
+    if (writeSucceeded) {
+      const backupMessage = backupSucceeded ? ` (backup: ${backupPath})` : ""
+      log(`Migrated config file: ${configPath}${backupMessage}`)
+    } else {
+      const backupMessage = backupSucceeded ? ` (backup: ${backupPath})` : ""
+      log(`Applied migrated config in-memory for: ${configPath}${backupMessage}`)
+    }
   }
 
   return needsWrite