@debugtalk/opencode-hashline

OpenCode plugin adapter for hashline — compact, line-anchored, tag-verified file edits. Powered by @oh-my-pi/hashline.

Instead of exact-string matching (which forces models to re-type old content and risks drift), hashline uses line-number anchors combined with content-hash tags so every edit is validated against the exact file snapshot the model saw. This plugin wraps the hashline engine as an OpenCode edit tool override and snapshot injection hook.

Package name: Published as @debugtalk/opencode-hashline on npm. The unscoped name opencode-hashline is used by a different package on the public registry.

Installation

npm install @debugtalk/opencode-hashline --save-dev

Add to opencode.json:

{
	"plugin": ["@debugtalk/opencode-hashline"]
}

Restart OpenCode. No build step — OpenCode loads the TypeScript plugin entry directly.

How It Works

The plugin overrides the built-in edit tool and injects snapshot tags into read output:

1. Read — output starts with [path/file.ts#A1B2] (4-hex content hash of the file)
2. Edit — [path/file.ts#A1B2] plus line-anchored ops; tag must match current file content
3. Drift — mismatch rejects the edit (with recovery when possible); re-read and retry

Edit syntax (format v2)

[src/foo.ts#A1B2]
SWAP 2.=2:
+    return newValue

INS.POST 10:
+    // new comment

DEL 5.=7

INS.HEAD:
+# SPDX-License-Identifier: MIT

| Operation | Syntax | Description | |-----------|--------|-------------| | Replace lines | SWAP N.=M: | Replace inclusive range N..M with + body rows | | Delete lines | DEL N.=M or DEL N | Delete range; no body | | Insert before | INS.PRE N: | Insert before line N | | Insert after | INS.POST N: | Insert after line N | | Insert head | INS.HEAD: | Insert at file start | | Insert tail | INS.TAIL: | Insert at file end | | Delete file | REM | Remove entire file (section header required) | | Move/rename | MV dest/path | Move file to dest/path |

Body rows are +TEXT only. The range deletes; the body is the final content for that range.

Rules

• Line numbers refer to the original file; they do not shift as hunks apply in one patch
• Every successful edit returns a new #TAG — use it for the next edit or re-read
• Ranges should cover only lines that change
• On stale tag or unexpected result: stop and re-read

Configuration

No configuration required.

Programmatic use (hashline core)

Use the upstream package directly:

import { Patch, Patcher, NodeFilesystem, InMemorySnapshotStore } from "@oh-my-pi/hashline";

Limitations

• SWAP.BLK N: not supported — tree-sitter block resolver is not bundled; use SWAP N.=M: line ranges
• write not overridden — create new files with the built-in write tool
• Files > 4MB — no snapshot tag on read (falls back to built-in edit behavior)
• OpenCode only — this npm package targets the OpenCode plugin runtime; see docs/cross-platform-plugins.md for other agents

Docs

• Test design
• Comparison vs built-in edit

License

MIT