# Factory Droid 0.199.0: SDK custom system prompts, managed BYOK defaults, explorer tool expansion

> The TypeScript SDK now supports custom system prompts that persist across session resumes. Org admins can set managed BYOK model defaults and apply model policies to service accounts. The built-in explorer droid can use all read-only tools (commands, web search, MCP) while file edits stay blocked. Question prompts gain keyboard controls, Mermaid diagrams render natively, and long sessions render with less lag.

| | |
|---|---|
| **Tool** | Factory Droid |
| **Version** | v0.199.0 |
| **Kind** | release |
| **Published** | 2026-08-18 |
| **Observed** | 2026-08-21 |
| **Significance** | 3/5 |
| **Breaking** | no |
| **Categories** | feature, capability |

## What changed


- **SDK custom system prompts:** set a custom system prompt for a session; it is kept when the session resumes.
- **Managed BYOK model defaults:** org admins can pick BYOK custom models as managed defaults for sessions and subagents in Enterprise Controls.
- **Service account model policies:** service accounts now appear in Enterprise Controls model policies.
- **Explorer tool access:** the built-in explorer droid can use every read-only tool (command execution, web search, MCP tools) while file edits stay blocked.
- **Keyboard controls for questions:** pick answers with Space or number keys, move between questions with Tab, go back to edit previous answers.
- **Mermaid diagram rendering:** diagrams render with the official Mermaid engine in the app.
- **Faster session rendering:** long sessions and streaming command output render with less lag.
- **Mission model settings:** choose models and reasoning defaults per mission from its settings.
- **Fix:** agent question context stays visible while you answer it.


## Sources

- [page_diff](https://docs.factory.ai/changelog/release-notes#v0.199.0) — retrieved 2026-08-21


## Community

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---
Canonical: https://changelogs.info/factory-droid/v0-199-0
Entity: https://changelogs.info/factory-droid
Event ID: `evt_2026-08-18_factory-droid_v0-199-0`
Licence: event synthesis © changelogs.info, CC BY 4.0. Linked sources belong to their vendors.