v0.19.8: Droid exec enhancements, custom model support, streaming JSON, and stability improvements

New features and enhancements

- droid exec Slack integration: Added slack_post_message tool to droid exec for posting updates to Slack channels
- droid exec streaming JSON input mode: Added streaming JSON input mode for multi-turn exec sessions for better automation workflows
- droid exec tool configuration: Added ability to enable/disable specific tools in droid exec sessions
- droid exec pre-created session IDs: Added support for pre-created session IDs in droid exec for better session management
- Initial prompt support: Added support for launching TUI with an initial prompt via command line
- GLM-4.6 support: Added LLM proxy support for GLM-4.6 with Fireworks, Baseten, and DeepInfra providers
- Azure OpenAI for GPT-5: Added Azure OpenAI support for GPT-5 Codex in TUI
- Custom droid generation: Added auto-generation of custom droids using LLM for faster setup
- MCP streamable HTTP servers: Added support for streamable HTTP MCP servers
- Model selector refresh: Updated model selector UI with improved organization and image support warnings
- Tab key auto-complete: Tab key now auto-completes custom commands without submitting for better UX

Bug fixes and stability

- droid exec session continuation fix: Fixed droid exec to correctly continue an existing session instead of overwriting session data
- Dynamic reasoning label for Codex models in UI
- AGENTS.md source paths now shown in settings for better transparency
- Better error messages when custom model JSON configuration is broken
- Manual update instructions when auto-update isn't available
- Fixed task subagents to properly terminate on abort
- Fixed file rename retry logic on Windows systems
- Fixed backslash rendering issues on Windows
- Major improvements to custom subagents reliability
- Fixed task tool subagents prompt for better execution
- Don't stop agent on cancelled file edits in spec mode
- Validated working directory exists before executing ripgrep
- Fixed subagents to inherit model from TUI parent session
- Truncated large MCP tool results to prevent context overflow
- Fixed /cost command with Fireworks cached input
- Added user-agent header to LLM requests for better tracking
- Locked down file system permissions for better security
- Fixed rendering for failed edit calls in spec mode
- Fixed compaction logic and retry without tool results
- Applied output transforms before compaction/caching
- Persisted session usage for accurate cost tracking
- Fixed /new command to reset timer and sessionId properly
- Fixed compaction retry without tool results
- Fixed screenshot reading with unicode normalization fallback