Build / Plan Mode (DSH plugin)

August 26, 2026 · View on GitHub

A persistent Cordis Host-and-Client plugin for DeepSeek Harness that adds a Build / Plan mode control to every session:

  • Build — ordinary DSH behavior. Tools, sandbox, and approvals are exactly stock.
  • Plan — Host-enforced read-only for the current turn. Useful observation stays available; file writes, shell/terminal/code execution, escalation, and unknown tools are denied before they run, and the agent finishes the turn with an ordinary written plan handoff that you review and execute in Build.
  • Mode is persisted per session (survives refresh, resume, fork, and restart) and frozen for the duration of a running turn. Click, Tab, and /bplan build|plan drive the same Host state.
  • Plan turns may spawn read-only background Research Children; everything else stays first-level and untouched.

Status: alpha — single-maintainer project, actively developed. The plugin mounts once from your Web profile composition and applies to all sessions independently of Agent presets. It does not modify DSH core, the npm installation, the Web shell, or shipped presets — it is pure user-layer composition.

Requirements

  • DSH 0.1.1-rc.2 (Web). This pin is exact: the plugin relies on seams verified against exactly this release (ACCEPTANCE.md); any DSH upgrade invalidates that record until the seam gate is re-verified.
  • An existing Web profile (for example the default web profile at ~/.dsh/profiles/web).

Install

From a local checkout

In the directory that contains this package:

dsh plugin --profile web add ./packages/build-plan-mode
dsh --profile web --dump-config

Restart DSH afterwards. The package ships its own bundle patch (cordis.patch.yml) which:

  1. inserts the plugin row (id: build-plan-mode);
  2. disables the native ui-plan client row so the built-in Plan control does not render twice.

If you manage the profile manually instead of using dsh plugin, install the dependency into the profile, add the package name to dsh.profile.bundles in the profile's package.json, and restart — the bundled patch is applied automatically as a bundle layer.

Verify

  • dsh --profile web --dump-config contains exactly one build-plan-mode row and ui-plan: disabled.
  • The Web UI shows the Build/Plan segmented control in the composer; /bplan plan switches the next-message mode.

Uninstall / rollback

Remove the package from the profile's dependencies and dsh.profile.bundles (or set disabled: true on both patch entries), then restart DSH. Every listener, projection, policy wrapper, Slot, style, keyboard handler, and child restriction is lifecycle-owned and disappears with the plugin; the native Plan UI returns unchanged. Session data written by the plugin reuses native event records only, so cold-loading without the plugin is always safe.

Development

npm install
npm run build        # emits everything into lib/ (outputs defined by scripts/lib-roster.mjs)
npm test             # focused plugin tests
npm run deploy:user-profile   # dev helper: copy the build into ~/.dsh/profiles/web

Design authorities: docs/build-plan-mode-spec.md (product behavior) and docs/build-plan-mode-design.md (implementation) inside this package. Acceptance evidence: ACCEPTANCE.md.

Note for forks intending to publish under a different name: rename the package in package.json and update the name: reference inside cordis.patch.yml to match.

Support

Use the repository issue tracker for questions and bug reports; see SECURITY.md for private vulnerability reporting, CONTRIBUTING.md for how to propose changes, CODE_OF_CONDUCT.md for community standards, and CHANGELOG.md for release history.

FAQ

Is this an official DeepSeek product?

No. This is an independent community plugin. It is not affiliated with, endorsed by, or supported by DeepSeek.

Does it modify my DeepSeek Harness installation?

No. It mounts from your Web profile composition only — zero changes to DSH core, the npm installation, the Web shell, or shipped presets. Removing it restores stock behavior.

Which DSH versions are supported?

Exactly 0.1.1-rc.2 (Web) today. The seam gate is pinned to that release; newer releases require re-running the gate first.

How does Plan enforce read-only?

A host-side monotonic tool guard denies mutation-class tools before they run, using public rc.2 seams only. No private APIs are wrapped, and no host patches are shipped or required.

Is there a plan mode in stock DSH already?

Native Plan exists but is step-oriented and takes over the review flow. This plugin provides a persistent per-session Build/Plan workflow instead, coexisting via profile composition.

License

MIT — see LICENSE.