dsh-file-checksum

A small, read-only DeepSeek Harness plugin that computes SHA-256 or SHA-512 for a file through the active Harness filesystem provider.

Unlike text-hashing tools, file_checksum reads the file's raw bytes without placing its contents in the model conversation. It works with the filesystem mounted by the current DSH profile, including compatible remote providers.

Install

Install directly from GitHub into a profile:

dsh plugin --profile web add github:yan9651688/dsh-file-checksum

For reproducible installs, pin a commit:

dsh plugin --profile web add github:yan9651688/dsh-file-checksum#<commit-sha>

Then start that profile as usual:

dsh --profile web --dump-config
dsh --profile web

This repository ships plain ESM JavaScript, so a GitHub install does not need a prepare build or pnpm allowBuilds entry.

Tool

file_checksum accepts:

Parameter	Required	Description
file_path	yes	Absolute path, or a path relative to the current agent session workspace.
algorithm	no	sha256 (default) or sha512.
expected	no	Expected hexadecimal digest. The tool returns match or mismatch.

Example prompt:

Use file_checksum to verify dist/app.tgz against this SHA-256: <digest>

The canonical result is structured for Native and Code Mode callers:

{
  "path": "/workspace/dist/app.tgz",
  "algorithm": "sha256",
  "digest": "...",
  "bytes": 12345,
  "verification": "match"
}

A checksum mismatch is a successful tool result with verification: "mismatch"; missing, non-regular, oversized, or unreadable files are tool errors.

Configuration

The bundle defaults to a 64 MiB whole-file limit:

- insert:
    - id: file-checksum
      name: dsh-file-checksum
      config:
        maxBytes: 67108864

Override the row in a later profile patch to choose a different positive integer, up to 256 MiB. The limit exists because the current DSH raw-byte filesystem API returns a complete bounded file rather than a byte stream.

Data and safety

• Reads through ctx.fs; it does not invoke a shell or bypass the active filesystem provider.
• Reads one regular file and never writes or deletes files.
• Declares checksum calls exclusive so one Native or Code Mode batch cannot multiply the configured whole-file memory limit.
• Does not access environment variables, credentials, or the network.
• Returns the digest, byte count, display path, and verification status; it does not return file contents.
• Records the successful or missing read through DSH's fs/observed event, matching the built-in file-read behavior.
• A digest identifies content integrity. It is not encryption and does not make sensitive data safe to share.

Known limitations

• One file per call; directories and Git tree hashes are not supported.
• Files larger than maxBytes are rejected rather than streamed or truncated.
• Separate agents or sessions may still run calls concurrently; each call can buffer up to maxBytes.
• The plugin is intended for DSH 0.1.0-rc.6 and later compatible 0.1.x releases. DeepSeek Harness is still in developer preview, so breaking upstream changes may require a plugin update.

Development

npm install
npm test
npm pack --dry-run

The tests mount the real Cordis context, tool registry, and local DSH filesystem provider. They cover standard hash vectors, binary bytes, expected-digest comparison, session-relative paths, filesystem observations, error cases, and lifecycle cleanup.

License

MIT