fix: accept valid workspace directory link counts

backend/src/workspaces/workspace-lock-root-lease.ts

@@ -4,7 +4,7 @@ export interface WorkspaceLockRootIdentityV1 { readonly schemaVersion:1; readonl
 export class CanonicalWorkspaceLockRootInput { private constructor(readonly workspaceId:CanonicalWorkspaceId, readonly owner:symbol){} static make(id:CanonicalWorkspaceId,owner:symbol){return new CanonicalWorkspaceLockRootInput(id,owner);} }
 export class BorrowedVerifiedWorkspaceLockRootLease { private constructor(readonly identity:WorkspaceLockRootIdentityV1, private readonly check:()=>void){} static make(i:WorkspaceLockRootIdentityV1,c:()=>void){return new BorrowedVerifiedWorkspaceLockRootLease(i,c);} assertLive(){this.check();} }
 function conflict(message="preprocessing conflict"):Error { const e=new Error(message); e.name="PreprocessingConflictError"; return e; }
-function exactStat(stat:WorkspaceFsAtStatV1,uid:number):boolean { return (stat.mode&0o170000)===0o040000 && (stat.mode&0o777)===0o700 && stat.uid===uid && stat.nlink===1n; }
+function exactStat(stat:WorkspaceFsAtStatV1,uid:number):boolean { return (stat.mode&0o170000)===0o040000 && (stat.mode&0o777)===0o700 && stat.uid===uid && stat.nlink>=2n; }
 export class WorkspaceSessionReadersLockLease {
  private live=true; private constructor(private readonly lock:OwnedWorkspaceFsAtRegularFile, private readonly root:OwnedWorkspaceFsAtDirectory, readonly rootIdentity:WorkspaceLockRootIdentityV1){}
  static make(lock:OwnedWorkspaceFsAtRegularFile,root:OwnedWorkspaceFsAtDirectory,id:WorkspaceLockRootIdentityV1){return new WorkspaceSessionReadersLockLease(lock,root,id);}