Label db sync failures by real cause

packages/db/src/repository.ts

@@ -1964,9 +1964,11 @@ function sanitiseSyncFailure(error: unknown): string {
 
 function classifySyncFailure(error: unknown): SyncFailureClassification {
   if (hasSyncFailureClassification(error)) return error.classification
+  // A body that is not JSON is an unexpected answer from the server, not a rejected login.
+  if (error instanceof SyntaxError) return 'upstream_response'
   const message = error instanceof Error ? error.message.toLowerCase() : ''
   if (message.includes('encryption') || message.includes('configuration') || message.includes('required before')) return 'configuration'
-  if (message.includes('unauthor') || message.includes('forbidden') || message.includes('credential') || message.includes('token')) return 'authentication'
+  if (message.includes('unauthor') || message.includes('forbidden') || message.includes('credential') || (message.includes('plex') && message.includes('token'))) return 'authentication'
   if (message.includes('timeout') || message.includes('network') || message.includes('connect') || message.includes('unavailable')) return 'upstream_unavailable'
   if (message.includes('plex') || message.includes('response') || message.includes('parse')) return 'upstream_response'
   return 'unknown'

packages/db/src/sync-failure-label.test.ts

@@ -0,0 +1,34 @@
+import { describe, expect, it } from 'vitest'
+import { failSyncRun } from './repository.js'
+import type { Database } from './repository.js'
+
+// failSyncRun writes one tagged-template UPDATE; the second interpolated value is the stored summary.
+async function storedSummary(error: unknown): Promise<string> {
+  let summary = ''
+  const database = (async (_strings: TemplateStringsArray, ...values: unknown[]) => {
+    summary = String(values[0])
+    return []
+  }) as unknown as Database
+  await failSyncRun(database, 'run-1', error)
+  return summary
+}
+
+describe('failSyncRun labels', () => {
+  it('records an unexpected non-JSON body as an unexpected response, not a rejected login', async () => {
+    expect(await storedSummary(new SyntaxError('Unexpected token < in JSON at position 0'))).toBe(
+      'upstream_response: Plex returned an unexpected response.',
+    )
+  })
+
+  it('does not call a non-Plex error that mentions a token an authentication failure', async () => {
+    expect(await storedSummary(new Error('invalid input syntax for type uuid: bad token'))).toBe(
+      'unknown: The sync did not complete.',
+    )
+  })
+
+  it('still labels a Plex token problem as authentication', async () => {
+    expect(await storedSummary(new Error('Plex token was unauthorized'))).toBe(
+      'authentication: Plex authentication was rejected.',
+    )
+  })
+})