feat(core): add session snapshot and revert system

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.
 

packages/core/src/control-plane/move-session.ts

@@ -84,15 +84,20 @@ export const layer = Layer.effect(
         return yield* new DestinationProjectMismatchError({ expected: current.projectID, actual: destination.id })
       }
 
-      const patch =
-        input.moveChanges && source.directory !== destination.directory
-          ? yield* git
-              .patch(current.location.directory)
-              .pipe(Effect.mapError((error) => new CaptureChangesError({ message: error.message })))
-          : ""
+      const moveChanges = input.moveChanges && source.directory !== destination.directory
+      const sourceRepository = moveChanges ? yield* git.repo.discover(current.location.directory) : undefined
+      if (moveChanges && !sourceRepository)
+        return yield* new CaptureChangesError({ message: "Source is not a Git repository" })
+      const patch = sourceRepository
+        ? yield* git.change
+            .capture({ repository: sourceRepository, path: current.location.directory })
+            .pipe(Effect.mapError((error) => new CaptureChangesError({ message: error.message })))
+        : Git.ChangeSet.make("")
       if (patch) {
+        const repository = yield* git.repo.discover(directory)
+        if (!repository) return yield* new ApplyChangesError({ message: "Destination is not a Git repository" })
         yield* git
-          .applyPatch({ directory, patch })
+          .change.apply({ repository, path: directory, changes: patch })
           .pipe(Effect.mapError((error) => new ApplyChangesError({ message: error.message })))
       }
 
@@ -104,7 +109,20 @@ export const layer = Layer.effect(
       })
 
       if (patch) {
-        yield* git.softResetChanges(current.location.directory).pipe(
+        const repository = yield* git.repo.discover(current.location.directory)
+        if (!repository)
+          return yield* new ResetSourceChangesError({
+            directory: current.location.directory,
+            message: "Source is not a Git repository",
+          })
+        yield* git.change
+          .discard({
+            repository,
+            path: current.location.directory,
+            index: "preserve",
+            untracked: "remove",
+          })
+          .pipe(
           Effect.mapError(
             (error) =>
               new ResetSourceChangesError({
@@ -113,7 +131,7 @@ export const layer = Layer.effect(
                 cause: error.cause,
               }),
           ),
-        )
+          )
       }
     })
 

packages/core/src/file.ts

@@ -0,0 +1,6 @@
+export * as File from "./file"
+
+import { Revert } from "@opencode-ai/schema/revert"
+
+export const Diff = Revert.FileDiff
+export type Diff = typeof Diff.Type

packages/core/src/filesystem/watcher.ts

@@ -112,7 +112,7 @@ export const layer = Layer.effect(
     }
 
     if (location.vcs?.type === "git") {
-      const resolved = yield* git.dir(location.directory)
+      const resolved = (yield* git.repo.discover(location.directory))?.gitDirectory
       const vcs = resolved ? yield* fs.realPath(resolved).pipe(Effect.catch(() => Effect.succeed(resolved))) : undefined
       if (vcs && !config.includes(".git") && !config.includes(vcs) && (!resolved || !config.includes(resolved))) {
         const ignore = (yield* fs.readDirectoryEntries(vcs).pipe(Effect.catch(() => Effect.succeed([])))).flatMap(