/cordis-plugin-development

Persistent Harness plugins

For implementation, use ordinary workspace files to author a bundle, then plugin_manager with action: install_bundle and the absolute package directory as target to install it in the current profile. Changes affect every session in that profile and survive restart. Load editing-cordis-compositions for agent preset changes.

Do not write the profile's package.json or cordis.patch.yml, create packages under $DSH_HOME, or run pnpm in the profile directory: install_bundle performs those steps, and each hand-made write outside the workspace needs its own approval. Every plugin_manager action, including list_plugins and list_bundles, also needs approval without Full access, so call it only when its result decides the next step.

Design or review

Read the applicable references below and inspect the proposed or existing plugin against current APIs. Report design choices or findings instead of following the installation workflow. Do not write files, install bundles, or change profile state unless the user requests implementation.

Enable a shipped plugin

A shipped bundle can resolve a plugin row and leave it disabled. The row id and its reason are in the shipped patch, packages/bundle/*/cordis.patch.yml in a source checkout. Write a workspace bundle whose patch overrides that row with disabled: false and inserts the Host rows it depends on; a source checkout's apps/cli/config/examples/<feature>/cordis.yml lists them for opt-in features. Packages shipped with dsh resolve from the dsh installation, so the bundle declares no dependencies on them. Install it with install_bundle.

Deliver a working plugin first

1. Resolve the requested result and destination. An unspecified visual destination is the current Harness Web UI; a standalone image or HTML file does not complete such a request. Choose reasonable visual details and implement a small first version; install it before visual refinement.
2. Discover only the APIs needed for that version: cordis_inspect_list, then targeted cordis_inspect_query calls. For UI, query Client Slots.listSubTree and the selected slot's registration options and props. For anything beyond a static decoration, such as tool policy, agent context, session-derived state, or Chat rows, read references/practices.md before choosing the extension point; for a user action in plugin UI, also read references/user-actions.md. Once the chosen slot and registration API are known, write the plugin.
3. Read the matching template under templates/ with the file-read tool and write its copies into one workspace directory, or write the installable package, patch, and required Host/Client files there yourself. Check JavaScript syntax and the manifest, then install it. Before that first installation, do not create preview HTML, mock shells, design variants, screenshot scripts, or rasterizer tooling. Use the installed plugin itself as the first preview.
4. Read the installation result: its application and warnings fields decide whether the change is live, not server logs, terminal output, process lists, or the page's boot payload. Confirm new rows with cordis_inspect_query, which needs no approval, rather than paging list_plugins. After application: applied, exercise the capability or inspect the live Client registration. Use the connected page for visual verification when browser control is available. For a page or panel, also verify design consistency: styles use only theme tokens, the plugin imports no Harness Client package such as @deepseek-ai/dsh-client-ui-primitives, the console shows no slot entry crash, and the view reads correctly in light and dark themes beside a comparable host page. For a user action, run the checks in references/user-actions.md. Scale verification to the change's risk; follow references/verification.md when browser control is unavailable. Restore any user setting or state changed while testing. State any verification limitation explicitly; installation and slot registration alone do not establish what the user can see.
5. Fix observed defects in the same plugin. When the requested result works, finish with its location and verification status. Do not continue speculative visual variants, optional features, or a new mock preview. Close any task list you created.

Knowledge sources, in order

1. Inspection: cordis_inspect_query answers exact Service methods and Event modes (Service, Event), a mounted plugin's Config JSON Schema (Config.listConfigs: filter the paged directory by name, then query the entry id), the Tools this Agent can call (Tool), and live Client Slots and theme tokens (Slots, Theme).
2. Package documentation: Config.listConfigs with name set to the package finds its entries; querying one entry returns its packageDir, the resolved package directory. Read <packageDir>/README.md. Bundled packages resolve from the dsh installation and profile-installed bundles from the profile, so never guess the path from $DSH_PROFILE_DIR.
3. Source: installed packages ship built lib/index.js and lib/types/**/*.d.ts with JSDoc under that same packageDir, not src/; a source checkout of DSH has packages/<group>/<name>/src. Read them when inspection and the README leave a question open, and start source-level diagnosis from a concrete installation or runtime failure.

DSH_PROFILE (profile name) and DSH_PROFILE_DIR (its directory, whose node_modules holds only profile-installed bundles) are set in every shell call of a profile-launched Harness and absent when the Harness was booted without a profile. Bash reads them as $DSH_PROFILE; PowerShell, which the Windows preset uses, reads them as $env:DSH_PROFILE. With dsh on the PATH, dsh --profile "$DSH_PROFILE" --dump-config prints the composed profile.

Read next

The files below live in this skill's base directory, which the skill tool reported, and the table is the complete list: do not enumerate that directory. In every deployment, including a source checkout, read these files with the file-read tool, write copies into the workspace with the file-write tool, and verify a copy by reading it back. In Desktop the directory sits inside app.asar, which only the Host process's own file reads can open; shell commands (ls, cat, cp, cmp), the glob and search tools (they run a native ripgrep process), node, and pnpm all fail on it. Never install or syntax-check a template in place; copy its contents into the workspace first.