fix(fs): observe absence before guarded recreation

packages/fs/tool-fs/src/write.ts

@@ -118,8 +118,8 @@ export function applyWriteTool(ctx: Context, sandbox: FsSandboxSurface): void {
         // model-facing remedy; anything else passes through.
         throw remediateFsError(sandbox.mapError(error, sandboxPolicy))
       }
-      // Record the observed version (a no-op when no policy plugin listens).
-      ctx.emit('fs/observed', target, outcome.version, exec)
+      // Record the present observation (a no-op when no policy plugin listens).
+      ctx.emit('fs/observed', target, { kind: 'present', version: outcome.version }, exec)
       return {
         path: target.displayPath,
         operation: outcome.operation,