Tianyi Cui
fbceb8dcd5
The linear replay resurrected the July spawn path: mode folded inline
and both confinement and the default cwd fenced to the deployment
workspaceRoot. Master (and the pre-rebase merge result) resolve the
policy once per spawn — resolve({ session }) — so session.header.cwd
is both the workspace-write boundary and the default shell cwd, as the
README already states. Restores the single resolve, threads the policy
through spawnArgv and the cwd fallback, re-expresses master's
session-root test on the terminal spec, and pins the recorded confine
policy in the explicit-cwd test.
Also from the same review round: the Python SDK exe build stages
pty.node from subprocess-local (node-pty's home since the relocation),
and fs-local's README counts the seam's eleven primitives.
43 lines
6.7 KiB
Markdown
43 lines
6.7 KiB
Markdown
# @deepseek-ai/dsh-fs-local
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English | [中文](README.zh.md)
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The **local-filesystem implementation** of the `ctx.fs` provider seam ([`@deepseek-ai/dsh-fs`](../fs)). Backs the eleven `FileSystem` primitives with the host filesystem; loading it as a plugin populates `ctx.fs`.
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```ts ignore-check
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import { LocalFileSystem } from '@deepseek-ai/dsh-fs-local'
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await ctx.plugin(LocalFileSystem, { cwd: process.cwd() })
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// ctx.fs uses the local backend; load @deepseek-ai/dsh-fs-policy for the
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// freshness policy gate and @deepseek-ai/dsh-tool-fs to expose read/write/edit.
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```
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## Behavior
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- **`resolve(path, opts?)`** — a relative `path` resolves against `opts.cwd` when the caller supplies one (the model-facing tools pass the calling agent's session cwd — see [the per-session cwd Agent Note](../../../.agents/notes/implemented/architecture/2026-07-02-fs-per-session-cwd.md)), else `config.cwd` (default `process.cwd()`); an absolute `path` ignores both. `opts.signal` is checked before and after local resolution, while a remote sibling backend may use it to abort its round-trip. The `targetKey` is the file's `realpath`, so two input paths reaching the same file through symlinks share one identity, and writes/edits land on the link target (preserving the link). A not-yet-existing path uses the realpathed parent directory plus basename when the parent exists; only an unresolvable parent falls back to the absolute path. `displayPath` is the absolute (un-resolved) path.
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- **Execution-world coordinates** — `processPath` exposes the target's canonical host path, `fileUrl` encodes that path through Node's platform-aware URL conversion, and `contains` uses platform path semantics to test identity or descendant containment without consumers parsing `targetKey`.
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- **`stat` / `lstat`** — return target metadata or `undefined` when absent. `stat` reports `FsInfo` for an already resolved target (`version` = an opaque token derived from bigint `dev:ino:size:mtimeNs:ctimeNs`, `type` of `file`/`directory`/`other`, byte `size`); path-shaped `lstat` reports `FsPathInfo` without following the final symlink and can therefore return `symlink`. Both check cancellation before and after their asynchronous metadata probe, so an abort that lands in flight reports `FS_ABORTED` rather than stale absence.
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- **`readText` / `streamText`** — UTF-8 only. `readText` reads the whole file; `streamText` decodes chunks so a huge file need not be held whole in memory and consumers can enforce their own retention bounds. Both reject invalid UTF-8 and NUL-byte binary samples (`FS_NOT_TEXT`) and non-regular targets. The `read` tool (`@deepseek-ai/dsh-tool-fs`) owns line windowing.
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- **`listDir`** — lists one directory level in stable `name.localeCompare()` order. Each entry carries the child basename, type, resolved child target (`displayPath` under the listed directory, `targetKey` as the realpath identity), and cheap stat metadata (`version`, plus `size` for regular files). It never opens or decodes file contents. Missing targets report `FS_NOT_FOUND`, file/special-file targets report `FS_NOT_DIRECTORY`, aborted calls report `FS_ABORTED`, permission failures report `FS_PERMISSION_DENIED`, and other listing or child metadata I/O failures report `FS_IO_ERROR`. Broken/disappeared children are returned as `other` without metadata, but permission/IO failures while resolving a child fail the whole listing with a structured `FsError`.
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- **`writeText`** — atomic: writes to a temp file opened exclusively (`wx`, `0o600`) inside a randomly-named private staging dir (`0o700`) next to the target, fsyncs, then renames over the target. An existing file's mode is preserved, while new files default to `0o600`; on Windows a new file inherits the destination directory's DACL, while replacement copies the target DACL onto the empty temp before writing and publishes through `ReplaceFileW` so the original access policy survives ([Windows DACL preservation Agent Note](../../../.agents/notes/implemented/bug-fix/2026-07-19-windows-atomic-write-dacl-preservation.md)). The `expected` guard is OPTIONAL: omitting it unconditionally creates-or-overwrites; `createIfAbsent` creates a missing target and rejects an existing one (`FS_NOT_OBSERVED`); `replaceIfVersion` replaces only at the observed version (a missing target or mismatch is `FS_STALE_VERSION`).
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- **`editText`** — atomic literal read-modify-write over the same primitive, serialized per target by a mutation lock. The `expected` guard is OPTIONAL: when supplied it verifies the version BEFORE literal matching (a stale edit reports `FS_STALE_VERSION`, never `FS_EDIT_NOT_FOUND`/`FS_AMBIGUOUS_EDIT` against newer content); omitting it edits the current content unconditionally. A missing target reports `FS_STALE_VERSION` either way. LF-normalizes for matching, restores the file's dominant CRLF/LF style, and rejects empty `oldString` / zero matches (`FS_EDIT_NOT_FOUND`) or ambiguous multi-matches without `replace_all` (`FS_AMBIGUOUS_EDIT`).
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The package-root SDK surface is the default/named `LocalFileSystem` class plus `Config`. Raw I/O lives in `src/fsio.ts` (Cordis-free, independently unit-tested); `src/index.ts` is the thin service wiring.
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## Model Experience
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Indirectly, through [`dsh-tool-fs`](../tool-fs/README.md), which renders this provider's line-windowed UTF-8 content, mutation acknowledgements, and exact provider messages in capped retained results while versions, atomic-write mechanics, and directory metadata remain internal.
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#### KV Cache effect
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No direct invalidation; the named consumer owns any request-prefix changes.
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## Known Limitations and Deferred Work
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- **`config.cwd` is not a sandbox** — it is a resolution default, not containment: absolute paths and `..` escape it. Enforce containment with a stricter `ctx.fs` backend or a permission plugin on the `tools/execute` waterfall ([capability-seam Agent Note](../../../.agents/notes/implemented/architecture/2026-06-17-filesystem-capability-seam.md#consequences)).
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- **An overwrite reads the whole prior file into memory** — solely as the UI diff basis; bounding that pre-read above a size threshold is deferred (`TODO(overwrite-diff-bound)`).
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- **Version tokens depend on filesystem metadata** — they combine device, inode, size, nanosecond mtime, and nanosecond ctime; a storage layer that cannot update any of those facts for a rewrite can still defeat the stale guard.
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- **`editText` holds the whole file (plus the edited copy) in memory** — streaming exists only on the read path.
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- **Binary detection is asymmetric** — reads NUL-sample only the first 8192 bytes while edits scan the whole buffer, so a file with a late NUL reads fine but rejects edits.
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- **The per-target mutation lock is in-process only** — a writer in another process is caught only by the optional version guard, never serialized.
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