deepseek-harness/packages/e2b/fs-e2b

@deepseek-ai/dsh-fs-e2b

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E2B implementation of the @deepseek-ai/dsh-fs provider seam. It has no config: load @deepseek-ai/dsh-e2b first, then this service in place of dsh-fs-local. The provider uses the owner's remote cwd and SDK handle, so file tools observe the same world as E2B-backed Bash processes.

Behavior

• Remote identity and metadata — relative paths resolve as POSIX paths against the caller cwd or ctx.e2b.cwd; realpath -m supplies canonical target identity without requiring the final file to exist. stat, no-follow lstat, and stable one-level directory listings project E2B metadata into the filesystem seam. Versions are opaque hashes of E2B metadata plus a per-write extended attribute.
• Execution-world paths — canonical targets expose absolute POSIX process paths, percent-encoded file: URIs, and provider-owned containment checks, so generic subprocess consumers never parse E2B target ids or apply host path rules.
• UTF-8 reads — whole reads and streamed reads preserve cross-chunk decoding, reject invalid UTF-8, and use the seam's 8192-byte NUL sample for binary detection. The model-facing tool still owns size selection and line windowing.
• Stable bounded reads — a dependency-free Node helper walks directory descriptors with no-follow opens and reads one held regular-file descriptor through the byte cap. Generic LSP queries therefore reject parent swaps, non-files, invalid UTF-8, and growth past the configured document limit before server startup.
• Atomic mutations — writes create a random sibling staging directory, change it to mode 0700 before uploading content, preserve an existing file's POSIX mode, and publish the staged file through E2B's same-filesystem atomic rename. The rename response supplies the committed version, so no fallible metadata request follows the commit point. E2B creates missing parent directories. Literal edits LF-normalize for matching, restore dominant CRLF storage, and serialize mutations per canonical target within the host process. Optional create/version guards keep the base seam's observed-state semantics.
• Failures and cancellation — E2B not-found, permission, abort, and other controller failures map to the existing FsError vocabulary. Cancellation is best-effort at earlier SDK request boundaries and checked immediately before rename. The signal is not forwarded into the rename RPC, so cancellation cannot interrupt the atomic commit; a successful rename is the commit point.

The provider does not copy, mount, or reconcile the host workspace. Giving it a host path as cwd creates a remote directory with the same spelling only.

Model Experience

Indirectly, through dsh-tool-fs, which renders remote UTF-8 content, directory results, mutation acknowledgements, and provider errors while E2B identity and transport remain internal.

KV Cache effect

No direct invalidation; the named consumer owns any request-prefix changes.

Known Limitations and Deferred Work

• No host synchronization — an empty E2B cwd stays empty until a tool, command, template, or external process populates it; local files are neither uploaded nor reflected back.
• Mutation coordination is host-process-local — another harness connection or remote command can race the adapter; version guards detect only metadata changes represented by E2B.
• Whole-file mutation costs remain — overwrite diffs and literal edits read complete files into host memory, and every operation incurs E2B controller latency.
• Custom templates must support the used Linux, Node, procfs, and envd features — realpath, chmod, mv, same-filesystem POSIX rename, streaming reads, file metadata extended attributes, /proc/self/fd, and no-follow descriptor opens are required; unsupported templates fail rather than degrade silently.