letta-ai/letta 0.16.6

v0.16.6

on GitHub

Highlights

• Expanded Conversations API support for default conversation / agent-direct mode.
• New conversations now initialize with a compiled system message at creation time.
• Fixed model_settings.max_output_tokens default behavior so it does not silently override existing max_tokens unless explicitly set.

Conversations API updates

• Added support for conversation_id="default" + agent_id across conversation endpoints (send/list/cancel/compact/stream retrieve).
• Kept backwards compatibility for conversation_id=agent-* (deprecated path).
• Added lock-key handling in agent-direct flows to avoid concurrent execution conflicts.

Conversation/system-message behavior

• Conversation creation now compiles and persists a system message immediately.
• This captures current memory state at conversation start and removes first-message timing edge cases.

Model/config updates

• Added model support for:
  • gpt-5.3-codex
  • gpt-5.3-chat-latest
• Updated defaults:
  • context window default: 32k → 128k
  • CORE_MEMORY_BLOCK_CHAR_LIMIT: 20k → 100k
• Anthropic model settings now allow effort="max" where supported.
• Gemini request timeout default increased to 600s.

Memory / memfs updates

• Git-backed memory frontmatter no longer emits limit (legacy limit keys are removed on merge).
• Skills sync now maps only skills/{name}/SKILL.md to skills/{name} block labels.
• Other markdown under skills/ is intentionally ignored for block sync.
• Memory filesystem rendering now includes descriptions for non-system/ files and condenses skill display.

Reliability and compatibility fixes

• Added explicit LLMEmptyResponseError handling for empty Anthropic streaming responses.
• Improved Fireworks compatibility by stripping unsupported reasoning fields.
• Improved Z.ai compatibility by mapping max_completion_tokens to max_tokens.

Full Changelog: 0.16.5...0.16.6