Secure file operations

Apus uses @openclaw/fs-safe for security-sensitive local file operations: root-bounded reads/writes, atomic replacement, archive extraction, temp workspaces, JSON state, and secret-file handling.

It is a library guardrail for trusted Apus code that receives untrusted path names, not a sandbox. Host filesystem permissions, OS users, containers, and the agent/tool policy still define the real blast radius.

Platform defaults

Apus retains fs-safe's auto native mode on macOS, Linux, and Windows. Supported operations use the installed native helper; operations with documented JavaScript fallbacks can use those paths when native support is unavailable.

No-clobber Root.move() calls, including the default and { overwrite: false }, require an installed native helper. On Linux, fs-safe 0.24 uses guarded fallbacks in auto mode when the filesystem rejects no-replace rename: files use identity-checked hardlink publication and unlink, while directories use plain rename. File destinations are never overwritten; the directory fallback can replace a concurrently created empty directory, but rejects nonempty directories and non-directory competitors. These moves do not promise crash durability. Native mode require refuses the unsupported primitive. With native mode off or a missing helper, moving to an absent destination still fails with helper-unavailable and leaves the source in place. A failed identity check after dispatch can reject after publication.

Doctor retains verified same-directory hardlink publication for a missing or disabled helper, including native loading failures. This compatibility path syncs the source and directory, preserves source identity, and refuses an existing claim. Native mode require and mutation-specific Root policies prevent this fallback. fs-safe owns unsupported native rename handling; Doctor reports its no-replace capability refusal without retrying publication. Unrelated permission and I/O failures remain errors. Interrupted moves are recovered only from an exact source/claim hardlink pair.

On Windows, secure credential reads need the matching native helper to verify ownership and ACLs on the same open file descriptor that supplies the bytes.

fs-safe publishes prebuilt native helpers as optional platform packages for Linux x64/arm64 (glibc and musl), macOS x64/arm64, and Windows x64. A normal package install selects the matching package without a compiler. Apus loads it through fs-safe's own dependency scope, including nested pnpm installs. Windows secure reads fail with permission-unverified when the helper is missing, outdated, disabled, or unsupported; there is no pathname-based permission fallback. This includes installs that omit optional dependencies and native Windows ARM64 runtimes. File SecretRef providers and GitHub identity credentials require these secure reads.

Apus leaves fs-safe's explicit environment settings and programmatic configureFsSafeNative() precedence unchanged:

# Guarded JavaScript paths; no-clobber moves and Windows secure reads are unavailable.
APUS_FS_SAFE_NATIVE_MODE=off

# Prefer native primitives when the installed platform helper loads.
APUS_FS_SAFE_NATIVE_MODE=auto

# Fail closed when an operation lacks the required native capability.
APUS_FS_SAFE_NATIVE_MODE=require

The generic fs-safe environment name also works: FS_SAFE_NATIVE_MODE.

Managed worktree acceleration uses isolated native operations for APFS and Btrfs cloning and metadata reads. Those operations retain automatic native selection without changing the Gateway process's configuration. An explicit native mode applies to the isolated operations too; off selects normal Git checkout. Native writes remain owned by a supervised child until it exits, so cancellation cannot release the destination for cleanup while the child is still writing.

fs-safe 0.23 removes the Python bridge. Apus keeps FS_SAFE_PYTHON_MODE and APUS_FS_SAFE_PYTHON_MODE as deprecated mode aliases when loading its runtime environment, with a deprecation warning. Explicit native settings and programmatic configureFsSafeNative() still take precedence. Replace the old names with FS_SAFE_NATIVE_MODE or APUS_FS_SAFE_NATIVE_MODE.

Python interpreter paths are not used. Remove FS_SAFE_PYTHON, APUS_FS_SAFE_PYTHON, APUS_PINNED_PYTHON, and APUS_PINNED_WRITE_PYTHON from deployments. Code that directly uses fs-safe must replace configureFsSafePython / FsSafePythonConfig with configureFsSafeNative / FsSafeNativeConfig and omit pythonPath.

Use require when all native-capable operations must fail if the platform binding is unavailable. auto allows documented fallbacks; no-clobber Root moves and Windows secure credential reads still require an installed native helper.

In fs-safe 0.21.2, require also refuses removal, recursive removal, directory creation, writable-open creation, and overwrite moves when the platform lacks the required confining primitive. An installed helper alone is not enough: recursive Root removal reports helper-unavailable on Linux without openat2 and on Windows. These strict-mode mutations perform additional identity checks and can be slower. See the upstream operation/platform matrix.

Keep require if those native guarantees are part of your deployment's security policy, and use a platform that supports the operations you need. Otherwise, the default auto mode retains the documented best-effort fallbacks and their existing performance.

The Linux GNU addons in fs-safe 0.20.0 target glibc 2.28 and load on Ubuntu 20.04's glibc 2.31. Older addons can fail with a missing GLIBC_2.33 or GLIBC_2.34 requirement. When a loader error reaches update diagnostics, support reports retain the missing numeric GLIBC version while redacting paths.

Candidate update snapshots copy plugin files through fs-safe's portable create-only publication path. They do not require a no-clobber move: copying preserves the serving files, rejects an existing destination, and checks the source against the admitted inventory. SQLite snapshots keep their separate integrity, content, and publication checks. An unavailable addon alone does not justify skipping those checks or abandoning a snapshot that can be made safely.

Windows path boundaries

An explicitly configured UNC root, such as \\server\share\workspace, and ordinary extended drive paths such as \\?\C:\workspace remain supported. Existing filesystem and permission requirements for each operation still apply.

A path confined to a workspace, plugin root, or extraction destination must use that boundary's own share. A foreign UNC share or device namespace is rejected before lookup, even if a filesystem alias could point back inside the boundary. Use a relative path or the admitted root's host and share spelling. Host and share comparisons ignore ASCII case; Unicode lookalikes do not identify the same host. Apus preserves valid local plugin aliases, including short names and trusted roots whose canonical location is a network share.

Do not strip \\?\ or \\.\ indiscriminately to work around a rejection. Ambiguous namespace spellings can change which host or device Windows reaches.

What stays protected without native acceleration

With the helper off, Apus still gets fs-safe's Node-only guardrails:

rejects relative-path escapes (..), absolute paths, and path separators where only bare names are allowed.
resolves operations through a trusted root handle instead of ad-hoc path.resolve(...).startsWith(...) checks.
refuses symlink and hardlink patterns on APIs that require that policy.
opens files with identity checks where the API returns or consumes file contents.
writes state/config files via atomic sibling-temp + rename.
enforces byte limits for reads and archive extraction.
applies private file modes for secrets and state files where the API requires them.

This covers Apus's normal threat model: trusted gateway code handling untrusted model/plugin/channel path input inside a single trusted operator boundary.

Ordinary reads return bytes from an admitted file handle without freezing the file against in-place writes. Writers should use atomic replacement when readers need complete old-or-new contents. Migration and publication owners separately verify their recorded content and ownership before removing or replacing files.

What native acceleration adds

The native helper provides policy-free filesystem primitives. fs-safe uses them for create-only writes, guarded hard-link publication, asynchronous sidecar creation, and explicit no-replace rename publication. Linux uses openat2 and renameat2. macOS uses descriptor-relative component checks and renameatx_np. Windows uses handle-relative operations, replacement-disabled rename, and descriptor-bound ACL inspection for secure credential reads.

The TypeScript layer still owns policy, validation, retries, cleanup, and fallback decisions. Native support narrows filesystem race windows. It does not turn fs-safe into a sandbox.

If your package deployment requires those native primitives, set:

APUS_FS_SAFE_NATIVE_MODE=require

In require mode, an unavailable or unloadable helper normally causes helper-unavailable; Windows secure credential reads report permission-unverified. Standalone sealed worker bundles have no dependency tree. They explicitly disable native loading, even when the host sets a mode override.

Plugin and core guidance

Plugin-facing file access should use apus/plugin-sdk/* helpers when a path comes from a message, model output, config, or plugin input. Plugins can use reviewed fs-safe primitives directly when they declare their own fs-safe dependency and retain the applicable path policy.
Core code should import fs-safe primitives from their focused package entry points. Keep Apus adapters where they own behavior, including secret-directory mode repair, archive durability, producer isolation, and public SDK compatibility. Pure re-exports are unnecessary: fs-safe owns its process defaults.
Apus's Plugin SDK retains the deprecated nonBlockingRead input hint for existing callers; omit it in new code. Safe reads always use nonblocking admission where supported, including when the old hint is false. Direct fs-safe calls no longer accept this option.
The SDK's atomic replacement helper also retains the ignored adapter chmod member for source compatibility. Direct fs-safe adapters must omit it; permissions use the retained file handle.
Archive extraction should use the fs-safe archive helpers with explicit size, entry-count, link, and destination limits.
Secrets should use Apus secret helpers or fs-safe secret/private-state helpers. Do not hand-roll mode checks around fs.writeFile.
For hostile local-user isolation, do not rely on fs-safe alone. Run separate gateways under separate OS users/hosts, or use sandboxing.