deepseek-harness/packages/fs/tool-str-replace-editor

@deepseek-ai/dsh-tool-str-replace-editor

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Standalone model-facing str_replace_editor over ctx.fs. It can be composed with persistent Bash, one-shot Bash, sandboxed Bash, or another terminal surface.

Config

Key	Default	Meaning
maxOutputChars	16000	Prefix characters retained for file and directory views.
description	Editor command guide	Model-facing tool description.

Tool

The schema provides view, create, str_replace, and insert over absolute paths. File views use one-based line numbers and preserve content tabs, so displayed text remains valid literal replacement input; directory views omit hidden, dependency, and Python-cache entries and descend two levels. A metadata miss from view, str_replace, or insert records confirmed absence before returning FS_NOT_FOUND, so a later create can recover an externally deleted path through the mounted policy's guarded-create flow; absence never authorizes str_replace or insert. Replacement requires one unique literal match and reports errors only in the public old_str vocabulary. Insert follows the selected zero-based insertion boundary without adding an implicit trailing newline. Mutations preserve tabs outside the requested edit.

Model Experience

Tool schema

What the model sees

The generated str_replace_editor schema, including the configured description. The plugin contributes no standalone system-prompt section.

Token effect

Fixed schema cost while str_replace_editor is visible.

KV Cache effect

Prefix-stable while the configured description and schema remain unchanged.

Tool results

What the model sees

Views return numbered text or a shallow directory listing. Calls expose file locations, and create/replace calls expose diff cards to presentation surfaces. Mutations return concise confirmations. Long views keep their prefix and append a clipping notice.

Token effect

Data-dependent and bounded by maxOutputChars plus the fixed clipping notice.

KV Cache effect

Append-only tool results follow the reusable request prefix.

Known Limitations and Deferred Work

• Operations target UTF-8 text; binary files are unsupported.
• str_replace intentionally rejects zero or multiple matches and has no replace_all argument.
• Every mutation goes through fs/write-intent or fs/edit-intent, resolves the current session sandbox policy, and delegates enforcement to the mounted filesystem and policy plugins.