[!NOTE] 📦 This plugin lives in the dsh-plugins monorepo — file issues & pull requests there. npm: @hy-sde-org/dsh-tool-ast

dsh-tool-ast — structural search & rewrite for DeepSeek Harness

A standalone package, installable as one plugin (two tools) for the DeepSeek Harness CLI:

package	tools	installed by users?
@hy-sde-org/dsh-tool-ast	ast_grep (structural code search) + ast_edit (structural rewrite, preview-first)	yes

ast_grep and ast_edit are a full parity port of oh-my-pi's coding-agent ast tools onto the harness tool contract (ctx.tools, ctx.fs, ctx.subprocess, ctx.systemPrompt). The engine is the packaged @ast-grep/cli native binary — it ships inside the npm dependency, so the plugin works on stock DeepSeek Harness deployments with zero upstream changes and no system ast-grep install.

The two tools

• ast_grep — syntax-aware structural search. Find every function, call, class, or declaration matching a tree pattern instead of a text substring: console.log($MSG) finds every console.log call, fn($X) finds every function fn with one argument. Patterns bind metavariables ($NAME, $_, $$$NAME) so a search can be turned directly into a rewrite.
• ast_edit — structural rewrite. Replace every node matching a pattern with a template that references the captured metavariables (console.log($MSG) → log.debug($MSG)). It always PREVIEWS first (apply defaults to false); pass apply: true to write the files. Rewrites are 1:1 structural substitutions — never text search-and-replace.

Both share one engine, one error vocabulary (AST_*), one set of caps, and one filesystem seam — which is why they ship in one package rather than two.

Relationship to the edit tool

For coding agents, edit (targeted, literal, line-anchored text changes) and ast_edit (structural AST changes) are complementary, not alternatives:

	edit / ast_edit in omp	edit / ast_edit in this package
pairing	auto-added together when edit is requested	both tools ship in this one package
apply model	edit applies directly; ast_edit previews + staged resolve	ast_edit previews by default; apply: true writes
guidance	"For one-off text edits, prefer the Edit tool"	idiomatic: ast_edit for codemods → edit for follow-ups

Both mutation paths write through the same ctx.fs seam (observation watermark, version guard, sandbox policy), so they compose safely in one session. The harness companion-preset pattern (code-edit) mounts a rich edit beside ast_edit; this package's bundle (below) provides read/write beside ast_grep/ast_edit, and can be pointed at the rich @hy-sde-org/dsh-tool-edit if you want the full editor.

Why

Text grep answers "where does this string appear"; an AST pattern answers "where does this code shape appear". ast_grep matches tree structure — console.log($MSG) finds every console.log call, fn($X) every one-argument call to fn — so a codemod cannot be missed because of formatting or string coincidence. Because patterns bind metavariables ($NAME, $_, $$$NAME), the match that found the problem turns directly into the fix: ast_edit rewrites every matched node with a template referencing the captures, always previews first (apply defaults to false), and writes only on apply: true — a 1:1 structural substitution, never a text search-and-replace.

For coding agents this is complementary to the edit tool, not an alternative: the idiomatic flow is ast_edit for codemods, edit for follow-ups. Both mutation paths write through the same ctx.fs seam, so they compose safely in one session — the relationship is detailed under Relationship to the edit tool below.

Prerequisites

• Node.js 22.19 or newer (the package's engines floor) with npm and pnpm on PATH;
• a DeepSeek Harness installation including the standard dsh CLI — the package's peer baseline is @deepseek-ai/cordis ~4.0.4 and @deepseek-ai/dsh-* ^0.2.0-rc.2;
• nothing else: the @ast-grep/cli native binary ships inside the npm dependency, so no system ast-grep install is needed.

Install

pnpm install --global @deepseek-ai/dsh

Direct from npm (published)

# both tools arrive in one command
dsh plugin --profile web add @hy-sde-org/dsh-tool-ast

dsh plugin add reconciles the profile's bundle list from the installed dsh.bundle.patch export, so after installation the hy-sde-ast-tool-ast row below is immediately active in the named profile.

You can also just depend on the package from your own tooling:

npm install @hy-sde-org/dsh-tool-ast   # or pnpm add / yarn add

From the git checkout (pre-publish / development)

git clone git@github.com:hy-sde/dsh-plugins.git
cd dsh-plugins
pnpm install
pnpm --filter @hy-sde-org/dsh-tool-ast build

AST_TGZ="$(cd dsh-tool-ast/packages/tool-ast && pnpm pack --pack-destination /tmp | tail -n 1)"
dsh plugin --profile web add "$AST_TGZ"

Verify

dsh web --dump-config   # look for the hy-sde-ast-tool-ast row

Run

Start the harness (dsh web) and ask the agent to search or rewrite structurally. The model-facing calls:

• ast_grep with pat: "console.log($MSG)" and lang: "TypeScript" — every console.log call, matched by tree shape rather than text, first 100 matches with $MSG captured per node.
• ast_edit with pat: "console.log($MSG)", rewrite: "log.debug($MSG)", path: "src" — previews every proposed rewrite; re-run with apply: true to write the files through the fs edit-intent waterfall (version-guarded, observation ledger).

Uninstall

dsh plugin --profile web remove @hy-sde-org/dsh-tool-ast

Already shipped? If a future DeepSeek Harness release adopts structural search/rewrite itself, skip installation — adding this bundle on top would duplicate the loader row and fail at boot.

What the bundle does

The plugin's cordis.patch.yml mounts one plain host row, exactly like the official harness's own tool-ast row in the stock base bundle. It consumes the deployment's host services — tools, subprocess (stock base mounts @deepseek-ai/dsh-subprocess-local), systemPrompt, and fs (stock base provides ctx.fs host-wide via @deepseek-ai/dsh-fs-sandbox) — so it needs no filesystem realm of its own:

• hy-sde-ast-tool-ast — @hy-sde-org/dsh-tool-ast, registering ast_grep/ast_edit beside the deployment's read/write/edit tools, sharing their fs instance, observation ledger, and sandbox policy.

Configure per deployment by patching the row by id:

- id: hy-sde-ast-tool-ast
  config:
    astGrepMaxMatches: 200
    astEditMaxHunkBytes: 8000
    timeoutMs: 45000

Pairing with the rich edit plugin

Install @hy-sde-org/dsh-tool-edit and this bundle together — that is the verified composition. Neither owns a filesystem realm, they share the host ctx.fs, and their tool sets are disjoint (ast_grep/ast_edit vs edit), so they compose freely on stock and hy-sde harnesses alike.

Engine behavior

• Spawn. The engine is a subpath of the @ast-grep/cli package, resolved by createRequire from the plugin — the platform binary arrives with pnpm install, identical to how ripgrep tooling ships.
• No shell layer. Every model input (pattern, rewrite, lang, strictness, globs, paths) is its own argv element — a hostile pattern stays inert.
• Strict parse. --json=stream output is parsed line-by-line; a malformed line fails the run (AST_FAILED) rather than being dropped.
• Exit semantics. exit 0 = matches; exit 1 + clean stderr = zero matches; exit 1 + stderr = AST_FIND_ERROR (bad path); exit 2 = AST_USAGE_ERROR; else AST_FAILED. Cooperative timeout / cancellation → AST_ABORTED.
• Apply is preview-first and version-guarded. ast_edit defaults to preview; apply: true writes only through the fs edit-intent waterfall with the observation/version guard, never a raw engine write.
• Caps. All result caps are configurable (see Config). The defaults: astGrepMaxMatches 100, astGrepMaxNodeBytes 2000, astEditMaxHunkBytes 4000, astEditMaxFiles 200, searchMetaMaxBytes 65536, rawOutputMaxBytes 8 MiB, graceMs 3000, stderrMaxBytes 64 KiB, timeoutMs 30000.

Development

pnpm install
pnpm -r check      # strict typecheck (tsc --noEmit)
pnpm -r test       # engine unit tests + real-engine integration suite
pnpm -r build      # tsc -> dist
bash scripts/release-public.sh --check      # pre-publish validation
bash scripts/release-public.sh --publish    # publish to npm

The test suite runs the REAL packaged ast-grep against real temp files, exercising ast_grep, ast_edit preview and apply (observation/version guard), sandbox denial mapping, and abort classification — no mocks of the engine.

Layout

packages/tool-ast/   @hy-sde-org/dsh-tool-ast — the plugin (both tools)
  cordis.patch.yml   the installable harness bundle
  src/core.ts        the engine: binary resolution, spawn, argv, JSON parse,
                     error vocabulary
  src/search.ts      the ast_grep tool body
  src/edit.ts        the ast_edit tool body (preview / apply)

License and attribution

This package is licensed MIT — the same license as its upstream oh-my-pi (https://github.com/can1357/oh-my-pi). The ast_grep and ast_edit tools are a full parity port of oh-my-pi's coding-agent ast tools (MIT License, © Mario Zechner 2025, © Can Bölük 2025-2026); the upstream copyright holders are recorded in LICENSE next to this package's own notice, and the upstream notice text is reproduced in full in THIRD-PARTY-NOTICES.md.

This plugin is a separate installable package; the harness remains the property of its own project.