P0 filesystem: PathSandbox over isolated Codex LOCAL_FS - #51
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Keep workspace authorization in PathSandbox, but use no-follow LOCAL_FS and a bounded walk so intermediate directory symlinks cannot escape the workspace. Co-authored-by: Cursor <cursoragent@cursor.com>
PathSandbox stays authorization only. codespace-fs now owns SymlinkRejected mapping and rollback mkdir/chmod so restore cannot follow a raced symlink. Co-authored-by: Cursor <cursoragent@cursor.com>
Keep PATH_ESCAPE as a wire-compat collapse for NotFound/NotDirectory/Io, and pin rollback against leaf and parent symlink swaps. Co-authored-by: Cursor <cursoragent@cursor.com>
Directory symlinks become SymlinkRejected instead of PATH_ESCAPE, while a regular file in the middle of a path stays NotDirectory. Co-authored-by: Cursor <cursoragent@cursor.com>
rustix's Linux backend returns OPNOTSUPP for chmodat(SYMLINK_NOFOLLOW) even on regular files, so rollback chmod has to open the leaf with O_NOFOLLOW and fchmod the fd instead of using pathname chmod. Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
crates/file-system(codespace-fs) wrapping CodexLOCAL_FSwithsandbox: None,follow_symlinks: false, and a bounded walk. Public types stay CodeSpace-owned (Path/ bytes / walk result /FsError).PathSandboxas the authorizer. That pre-check is not the I/O safety boundary. The shared primitive is CodexLOCAL_FSno-follow: Runner-owned read/find/rollback go throughcodespace-fs;apply_patchmutation usescrates/patch→apply_patch_with_optionson the same pin.FsError. After a failed no-follow I/O (ENOTDIR/ELOOP), the adapter inspects path components without following: an ancestor symlink isSymlinkRejected; a regular file in the middle isNotDirectory. The runner maps variants only.NotFound/NotDirectory/ genericIocurrently collapse intoPATH_ESCAPE. That is not the final filesystem taxonomy. Operator-registeredworkspace.rootis the trust anchor; descendants under it are never followed.read/findstay workspace-relative with frozenLIVE_TOOLS. NoWIRE_PROTOCOLbump.64/10_000/50_000). CI scans a narrowfs_key_allowedlist and runs the adapter via--manifest-path. Remaining P0 subgraph: linux-sandbox → network.Test plan
cargo test --manifest-path crates/file-system/Cargo.tomlcargo test -p codespace-runner --lib(including directory-symlink ancestor, find skip, rollback symlink-swap)cargo test -p codespace-server --test read_find --test protocol_compat./scripts/check-no-model-deps.shpython3 -B scripts/check_docs.pycrates/file-systemplus workspaceMade with Cursor