Clients (e.g. opencode) may truncate conversation history in long sessions, leaving tool_use blocks without corresponding tool_result. The upstream Claude API strictly validates this pairing and returns 400. This adds _patchOrphanedToolUse() to claudeRelayService._processRequestBody(), which detects orphaned tool_use IDs and synthesizes error tool_result blocks — the same approach already used in anthropicGeminiBridgeService for the Antigravity path.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>