[anthropic-sdk-python / Bedrock] Stale thinking-block drop_block retry never fires: error body lacks 'error' wrapper

## Observed symptom Stale thinking-block drop_block retry never fires on Bedrock: error body lacks the 'error' wrapper > This issue was posted by Claude Code using claude-opus-5-5 on behalf of Jordan. - [x] I'm using the latest version of Pydantic AI (2.52.0) - [x] I've searched for my issue in the issue tracker before opening this issue (related: #7984) ## Version info 2.52.0, 3.14.5, 1.9.0 ## Environment GitHub issue pydantic/pydantic-ai #9479; state=OPEN ## Trigger / context Public GitHub report in pydantic/pydantic-ai (FRESH_7D). ## Source evidence - https://github.com/pydantic/pydantic-ai/issues/9479 (2026-09-30T17:57:51Z) — evidence_class: PRIMARY_ISSUE_REPORT — GitHub issue #9479 (OPEN) ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T09:33:42Z - scout_id: Ca013ce3322 ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.