Problem:
- PR #186 fixed empty content for assistant messages and history user messages
- But current user message (isLastMessage == true) was not fixed
- When user message contains only tool_result (no text), content becomes empty
- This causes 'Improperly formed request' errors from Kiro API
- Compaction requests from OpenCode commonly have this pattern
Solution:
- Move empty content check BEFORE the isLastMessage branch
- Apply fallback content to ALL user messages, not just history
- Add DefaultUserContentWithToolResults and DefaultUserContent constants
Fixes compaction failures for OpenCode + Quotio + CLIProxyAPIPlus + Kiro stack
Apply code review feedback from gemini-code-assist:
- Move fallback strings to kirocommon package as exported constants
- Update kiro_claude_request.go to use shared constants
- Update kiro_openai_request.go to use shared constants
- Improves maintainability and avoids duplication
Fix three issues in Kiro OpenAI translator that caused "Improperly formed request"
errors when processing LiteLLM-translated requests with tool_use/tool_result:
1. Skip merging tool role messages in MergeAdjacentMessages() to preserve
individual tool_call_id fields
2. Track pendingToolResults and attach to the next user message instead of
only the last message. Create synthetic user message when conversation
ends with tool results.
3. Insert synthetic user message with tool results before assistant messages
to maintain proper alternating user/assistant structure. This fixes the case
where LiteLLM translates Anthropic user messages containing only tool_result
blocks into tool role messages followed by assistant.
Adds unit tests covering all tool result handling scenarios.
