feat(core): add session snapshot and revert system (#33226)

AGENTS.md

@@ -28,6 +28,7 @@ Examples: `fix(tui): simplify thinking toggle styling`, `docs: update contributi
 - Rely on type inference when possible; avoid explicit type annotations or interfaces unless necessary for exports or clarity
 - Prefer functional array methods (flatMap, filter, map) over for loops; use type guards on filter to maintain type inference downstream
 - In `src/config`, follow the existing self-export pattern at the top of the file (for example `export * as ConfigAgent from "./agent"`) when adding a new config module.
+- In Effect generators, bind services to named variables before calling methods. Do not use nested service yields such as `yield* (yield* Foo.Service).bar()`.
 
 Reduce total variable count by inlining when a value is only used once.