FS Observation Policy
Domain: Security & Permissions
Motivation
dsh-fs-observation-policy is a read-before-edit gate that makes filesystem tools require an agent to read a file before overwriting or editing it. It also rejects a mutation when the file has changed since that read (FS_STALE_VERSION), and returns a clear instruction to re-read and retry. Reading a missing path authorizes guarded creation, while concurrent creation remains protected. Observed state is not persisted, so resumed sessions must re-read targets.
Concrete Example
An edit on app.ts without a prior read fails with FS_NOT_OBSERVED and policy reason edit requires reading "app.ts" first; after the read, the edit succeeds as a compare-and-swap against the observed version.
Analogy
It is the librarian who says “show me the card you got when you first looked at this book” before letting you write in it — and re-checks that the pages have not been turned since.