formatters

DeepSeek Harness (dsh) plugin: per-extension formatter commands with a model-facing format tool and optional auto-format-on-edit.

The harness web UI is read-only, so this plugin works through the seams the agent uses to write: a format tool over per-extension formatter commands (prettier, black, gofmt, ...) and, when enabled, automatic reformatting after every successful edit/write via the tools/post-execute waterfall. Formatters run through ctx.subprocess — never shell-interpreted.

Settings

Since 0.2.0 a settings form is not registered: the settings service projects the volatile Config fields of the active profile's entries, so this plugin's own Config is its form and its namespace is its entry id formatters. The plugin declares it ships its own page for that form.

Both fields are .volatile(), which is what makes the entry projectable at all — volatileForm returns nothing when a Config declares no volatile field, so the entry is silently dropped from describe() and every write to it is refused. Both are the user's choice rather than a deployment fact: the table is machine-local (which formatter exists and under what name differs per workstation) and the toggle is a workflow preference.

formatters:
  autoFormatOnEdit: true
  formatters:
    ".ts": { argv: [npx, prettier, --write] }
    ".py": { argv: [black, -q] }

Each field is a live reference: the Loader commits a settings write into the very object apply received instead of remounting, so both the format tool and the auto-format hook read them with .get() per call and pick up a settings edit without a restart.

CLI

dsh formatter list
dsh formatter add <ext> <command...>     e.g. dsh formatter add .ts npx prettier --write
dsh formatter remove <ext>
dsh formatter set-auto <on|off>

Layout

• src/settings.ts — the formatters namespace (this plugin's entry id), the Config schema that is also its settings form, and the formatterFor / autoFormatEnabled helpers.
• src/format.ts — the shared formatting runner (formatFile) and path helpers.
• src/index.ts — plugin: settings page declaration, format tool, auto-format hook.
• bin/formatter.mjs — the dsh formatter CLI.
• check-plugin.mjs — boot-verify harness (npm test).