[joaoguimaraespro]

Problem

IBKR answered 1025 "Too many failed attempts" and blocked the Flex token. The server logs show repeated SendRequest calls. Three causes added up:

1. The scheduler decides "due" from the last successful sync only. A failing IBKR connection was retried every 30 minutes, all day.
2. Backfill probing (IBKR: don't fail the sync on Flex 1003 (history before the account existed) #29/IBKR: later syncs no longer fail with 1003 #35) could spend up to ~11 failed requests in one sync.
3. 1025 is undocumented and was treated as a generic error.

Changes

• SyncSchedule (pure, unit tested) decides when a connection is due. After a failed attempt it waits 6 h for IBKR, 2 h for others, and 12 h after a lockout (1025 / "too many failed attempts" in the job's errors). The normal cadence is unchanged. BrokerSyncService loads the last finished job of the past 2 days per connection to apply it.
• 1025 gets its own temporary error explaining the pause and suggesting a new token if it persists. The UI shows a translated hint that also tells the user not to press Sync meanwhile, since that extends the block.
• Backfill spends at most 4 failed requests per sync. The rest of the history comes in later syncs.

Test plan

• New SyncScheduleTests: back-off after a failure, 12 h lockout pause, normal cadence, lockout detection
• New: 1025 is reported as temporary after a single request
• Updated: give-up after ≤ 4 failed probes
• Integrations.Tests, Integration (Portfolio), web unit tests 52/52