The trio
- Timeline record off: Windows stops writing task history locally;
- Upload(where applicable): sync to account-cloud projects is separately tunneled and separately toggleable;
- Clear: the per-user purge action lives under the same settings family.
Consequence map: disabling re-introduces the “which window had this file yesterday” problem for Timeline-heavy users. If you use Win+Tab for resumption, expect it to empty; Alt-Tab recency isn't affected — it's not Timeline-fed.
Why this is per-account by design
Activity history answers “what did I do” — writing it account-scoped would hand your work trail to anyone on the machine. If your household PC has per-user accounts, that's the whole story; second proofs of why shared-account setups erase any hope of per-person privacy boundaries.
ProofTune ProjectEngineering notes — every claim here names the bytes a real tool touches. Verify first, install second.