Respect provider rate limits and preserve bank connections on throttling

README.md

@@ -142,6 +142,8 @@ Finance Duck verifies the callback state, exchanges the returned code for a `ses
 
 Initial synchronization requests the selected number of **calendar months of booked transactions per account**, defaulting to **12 months**. The bank may provide less history. The choice is saved with the bank connection and reused on reconnection. Subsequent daily synchronization overlaps each account's last successful sync by **14 days**. **Sync now** starts a manual synchronization. Existing accounts keep their successful-sync cursors: changing the history choice or reconnecting does **not** backfill them. Older history can be imported with CSV.
 
+**HTTP 429 is a provider rate limit, not evidence that bank consent has expired.** Bank reads honor `Retry-After` and use bounded exponential retries. A longer or exhausted limit pauses further requests until the reported retry time; failed accounts keep their previous sync cursors and imported data. Session checks use the saved account metadata rather than fetching every account's details again. A failed session is reported once instead of also marking each of its accounts unavailable. After the cooldown, **Sync now** can retry; the warning clears after a successful sync. One-time authorization and code-exchange requests are never automatically replayed.
+
 ### Import older history for a connected account
 
 Open **Accounts**, find the account, and click **Import older history**. Choose **Months back** (default **12**, whole numbers from **1 to 120**) and confirm. This requests that account's booked transactions from the selected number of calendar months ago through today; the bank may provide less history.
@@ -359,6 +361,8 @@ Bank imports do **not** require this key. Without AI, explicit merchant-default
 
 Every AI classification requests `provider.data_collection = "deny"`, `provider.zdr = true`, and `provider.require_parameters = true`. Unsupported private routing fails rather than falling back to a less restrictive provider. Amount sharing is off by default. Keep OpenRouter account prompt logging disabled as well. Automatic redaction minimizes data; it is not a guarantee that arbitrary transaction prose is anonymous.
 
+Classification honors HTTP 429 `Retry-After` delays (seconds or HTTP dates), with exponential backoff when no usable delay is supplied. It makes at most **four attempts**, with at most **two minutes of automatic waiting**, preserving the same model, sanitized prompt, and privacy controls on every attempt. Imports and classification previews share a cooldown, so remaining records cannot immediately hammer a rate-limited provider. Long or exhausted limits leave records unclassified with a retry-time error; local merchant rules still work. After the cooldown, run **AI classification → Analyse** again for previously failed records—repeating a bank import does not reclassify existing transactions.
+
 ## Data, backups, and recovery
 
 Back up the **entire canonical finance directory**, including registry files, journals, `config.toml` when present, and operational/recovery state, plus any separately stored environment-managed secrets. `state/openrouter.json` and `state/enablebanking.json` contain UI-managed credentials: protect backups accordingly, including the matching banking session state. Stop the service for a consistent filesystem backup. DuckDB under `cache/` can be excluded and rebuilt.