--- title: "Authoring a Plugin" description: "Discover the current Kandev plugin contract, choose a recipe, build a package, and smoke-test it safely." status: experimental --- # Authoring a Plugin This is the canonical developer entry point for Kandev runtime plugins. Use it to choose a supported surface, edit manifest.yaml, implement the backend, native UI, or isolated web app, package it, and test it against a disposable development instance. The [plugin manifest reference](plugins-manifest.md) owns field-by-field schema details; [Plugins](plugins.md) covers operator installation and lifecycle. The official scaffold is [kdlbs/kandev-plugin-template](https://github.com/kdlbs/kandev-plugin-template). Production plugins live in their own repositories. The in-tree fixture is test support, not a starter repository. ## Quick workflow 1. Choose the closest recipe in this page. 2. Copy the template and edit manifest.yaml: identity, runtime executable or `ui.web_apps`, UI paths, capabilities, events, webhooks, and config. 3. Implement through the Go pluginsdk, the native frontend registry/Host API, or the relative canvas protocol for an isolated web app. 4. Run the plugin repository tests, vet/lint, and build. 5. Stage the package, run plugin-pack, inspect the archive and generated checksums, then install it in a disposable Kandev instance. 6. Smoke-test every declared hook and capability, then bump the version for the next iteration. ## Lifecycle ![Plugin authoring lifecycle: package validation and safe extraction feed the supervised Go runtime path and the browser native-UI path, which ends in plugin initialization.](../screenshots/plugin-authoring-lifecycle.svg) [Open full-size SVG diagram][plugin-authoring-diagram] [plugin-authoring-diagram]: ../../docs/screenshots/plugin-authoring-lifecycle.svg The two lower paths are intentionally separate: the Go subprocess uses the host gRPC connection, while the browser receives static bundle assets and then calls `registerKandevPlugin`. Installation validates the manifest, archive paths, checksums, managed runtime, and the current host executable before extraction. Kandev then supervises the declared subprocess and injects a Host connection. Installing a new version does not remove the one it replaces: that version stays on disk as the rollback target, and only the versions before it are deleted, once the new one is confirmed running. Two extracted versions is therefore the steady state for a plugin that runs; a plugin that is disabled or failed to start keeps every version it has, and `data/` is never part of that cleanup. The UI bundle is static package content loaded by the browser; it does not run inside the backend subprocess. On disable or uninstall, the host calls destroy when present and bulk-revokes registrations, styles, routes, handlers, and navigation. Reloads and updates are generation-safe: a slow or failed initialization is not treated as a definitive revocation, while a successfully ready generation can remove panels it no longer registers. Each attempted generation owns its requests, subscriptions, modals, task-link dialogs, toasts, and review surfaces. Timeout, failure, reload, disable, or uninstall aborts and cleans those resources before calling `destroy` exactly once; late callbacks from an expired generation are fenced from host state. ## Package and data layout ```text -.tar.gz ├── manifest.yaml # required, validated first ├── server/ │ └── plugin--[.exe] # one or more declared binaries ├── ui/ │ ├── bundle.js # optional native ES module │ ├── plugin.css # optional styles │ └── assets/ # optional files referenced by UI ├── assets/ # optional manifest icon/assets ├── checksums.txt # generated by plugin-pack └── checksums.txt.sig # optional signature ``` runtime.executables maps a platform key such as linux-amd64 to a clean package-relative path such as server/plugin-linux-amd64. Windows values must end in .exe. The host platform's key must be present at install time. A UI-focused native plugin still ships a managed backend executable because the current installer requires `runtime.type: binary`. That executable can be a no-op pluginsdk.UnimplementedPlugin server. An isolated web-app package can omit `runtime`. It contains a static entry document and the files that document imports. Use the `ui.web_apps` fields in the [manifest reference](plugins-manifest.md#isolated-web-applications). Kandev injects KANDEV_PLUGIN_DATA_DIR into the subprocess. It is the durable, per-plugin directory for arbitrary files or a plugin-owned database: ```text ~/.kandev/plugins//data/ ``` The directory is shared across installed versions, survives restarts and upgrades, and is removed on uninstall. Keep small structured values in Host state instead, and never write arbitrary files elsewhere in the Kandev data directory. ## Choose a plugin shape | Shape | Package contents | Typical contract | Minimal capability set | | ----------------- | ---------------------------------------------------------- | ----------------------------------------------------------------------- | ------------------------------------------------------ | | Backend plugin | Go binary and manifest | events, webhooks, Host data, state, secrets, or utility-agent calls | only the capabilities used by the backend | | UI-focused plugin | no-op managed binary, ui/bundle.js, optional styles/assets | routes, nav, named slots, WebSocket handlers, keybindings, shared store | ui.bundle; add ui.keybindings when declaring shortcuts | | Combined plugin | Go binary plus UI bundle | UI calls a declared webhook or backend API; backend uses Host | union of the two surfaces, kept least-privilege | | Isolated web app | manifest plus static HTML, CSS, JS, and assets | task or workspace canvas inside a sandboxed iframe | only the Kandev data, event, state, and network access it needs | ## Build an isolated web application Use this shape for a canvas app that runs packaged browser code. The package does not need a Go backend or an injected Kandev JavaScript API. 1. Add one or more `ui.web_apps` entries with a package-relative HTML entry. 2. Set `placements` to `task-canvas`, `workspace-canvas`, or both. 3. Build the app with relative `./_kandev/v1` requests. 4. Declare only the Kandev capabilities and exact HTTPS `network_origins` that the app needs. 5. Package the manifest and static files as a gzip-compressed tar archive. For a new owner-authorized task canvas, the first valid release can receive only its declared supported permissions through the initial permission policy. Kandev data access is limited to the current workspace while the canvas stays placed in its creating task. Imported packages and later permission increases need human approval. Keep `network_origins` as exact HTTPS origins. Do not use wildcards, paths, credentials, query strings, or fragments. For example, a page can read task data with the browser Fetch API: ```js const response = await fetch("./_kandev/v1/data/tasks"); if (!response.ok) { throw new Error("The task data request failed"); } const tasks = await response.json(); ``` Use `./_kandev/v1/events` for the event stream. Read both `scope_kind` and `data_scope_kind` from `./_kandev/v1/context`: the first describes placement, and the second describes the Kandev data boundary. Keep all protocol paths relative so the same package works in task and workspace placement. For task lists, follow `page_info.next_cursor` to load every page. Do not set `workspace_id` to another workspace or copy a capability URL from the host. For recorded workflow movement, the browser can GET `./_kandev/v1/data/tasks/{task_id}/step-transitions` with `api_read:tasks`. A workspace canvas can GET `./_kandev/v1/data/workflows/{workflow_id}/transition-groups` with both `api_read:tasks` and `api_read:workflows`. The latter is denied to a task canvas until the user promotes it. Both return bounded `{items,page_info}` pages; use the opaque `next_cursor` to continue. The equivalent optional backend Host extension is `pluginsdk.TransitionHistory(host)`. It exposes `ListTask` and `ListWorkflowGroups` with the same fields and grants. Kandev injects a reserved startup bootstrap into the packaged entry document. It runs before authored scripts, reports an initial document error when one is observed, and checks `./_kandev/v1/context` after the document loads. The host reveals the frame only after it receives a versioned acknowledgement for the current startup attempt. A missing acknowledgement or context failure makes the canvas recoverable after 15 seconds. Keep the entry document and its relative assets valid HTML, and make the app render its own loading and error states after startup. The frame is same-origin with Kandev and canvas code is trusted with the viewing user's ordinary user-session authority. It can use `localStorage`, `sessionStorage`, IndexedDB, same-origin cookies, and the host DOM. Keep Kandev protocol requests relative and do not copy capability URLs or tokens. Use the state protocol for small app-specific shared values and JavaScript memory for temporary values. Capability URLs, release bindings, scope checks, and declared grants still govern every Kandev protocol operation. Network access uses exact HTTPS origins that a user approves. Wildcards, origin paths, query strings, credentials, and remote scripts are not allowed. Keep scripts, styles, fonts, and images in the package. Forms cannot submit to external origins. The runtime sets `form-action 'none'`. External requests to approved origins are sent directly by the browser. Kandev cannot inspect them after they leave the browser, so a release, grant, scope, archive, disable, or removal notification immediately tears down the matching iframe. A replacement iframe gets a fresh runtime binding. The validator rejects unsafe paths and unsupported files. It also limits a package to 10 MiB compressed, 25 MiB expanded, 512 files, and 5 MiB per file. The manifest limit is 64 KiB and the normalized path limit is 240 bytes. Build and test the archive outside Kandev. Kandev validates the archive before it stores or runs a release. Use [Agent-authored Canvases](canvases.md) for creation, permission review, promotion, Quick Chat editing, and recovery. ### Share a portable canvas For a canvas that another workspace can install, add the `distribution` block described in the [manifest reference](plugins-manifest.md#portable-canvas-distribution-metadata). Choose `static` when the packaged application is the only source you want to share. Choose `project` when you retain a bounded editable project under `distribution/source/`. Do not put screenshots in the package. After a valid release is active, use **Share canvas** in the host or workspace canvas list. Prepare and download the bundle and source archive, inspect them for private content, and share them as files or HTTPS links. This action does not create a repository, release, registry entry, or pull request. To list the canvas, publish the exact bundle as a versioned release asset and add a `kind: canvas` entry with one to eight ordered `previews` objects to a trusted registry. The first preview is the cover. Preview URLs and alt text are registry metadata and are not part of the package manifest. There is no separate HTTP server to launch. pluginsdk.Serve owns the go-plugin/gRPC handshake and Host injection. The backend implements pluginsdk.Plugin (OnEvent and/or HandleWebhook) and embeds pluginsdk.UnimplementedPlugin for no-op defaults. ### Contribute an agent tool A managed plugin can contribute task-aware MCP tools through the same supervised gRPC process. Add an `agent_tools` declaration to `manifest.yaml` and implement the optional `pluginsdk.AgentToolPlugin` interface: ```yaml agent_tools: - name: add_tag description: Add an existing tag to the current task. surfaces: [kanban-task] input_schema: type: object properties: tag_id: { type: string } required: [tag_id] additionalProperties: false annotations: read_only_hint: false destructive_hint: false idempotent_hint: true ``` The host exposes the readable canonical name `kandev__` (for example, `kandev_task_tags_v1_add_tag`). Punctuation in the stable plugin ID becomes an underscore. Very long names receive a short stable hash suffix after the slug is truncated. Tool names are host-owned; the plugin-local `name` is used for the gRPC dispatch. Tools may target `kanban-task`, `office-task`, or both. They are not exposed to configuration or external MCP clients. Kandev validates the input and optional output JSON Schemas, supplies task/session/workspace/surface context, enforces a 30-second deadline and 1 MiB result limit, and does not retry calls. The optional SDK method is: ```go InvokeAgentTool(context.Context, *pluginsdk.AgentToolRequest) (*pluginsdk.AgentToolResult, error) ``` The request includes immutable invocation, task, session, workspace, and surface context. Return required fallback text, optional structured content, and `IsError` when the operation failed. Declaring a tool does not grant Host API capabilities; use the existing `capabilities` fields for those permissions. ## Security and capabilities Plugins are privileged installed code. The capability list gates Host RPCs; it is not an operating-system sandbox. A backend subprocess inherits the Kandev process environment, and a UI bundle runs as same-origin JavaScript with the curated React, UI, and app-store surface. - Plugins do not receive direct database access. Use typed Host readers/writers, Host state, secrets, events, and the data directory. Do not import Kandev internal/... packages or call undocumented REST endpoints. - state gates Host state; secrets gates RevealSecret and plugin-owned secret methods; each api_read resource gates its reader; api_write gates task/message mutations and interaction responses; agent_invoke gates utility-agent calls; and capabilities.events controls event delivery. - GetConfig and EmitEvent are ungated. GetConfig returns this plugin's own config, including cleartext secret fields, so do not log or commit it. - Declared webhook keys default to public. Set `webhooks[].access: authenticated` for browser UI and billable operations. Kandev does not enforce `webhooks[].method`; public integrations must still validate the provider signature and replay/timestamp rules before side effects. - An authenticated webhook is reachable from your panel with any method, `GET` included: `host.api.fetch` is same-origin (or carries an accepted `Origin` in a split-origin install), which is what the host checks. You do not need to force a read onto `POST`. - capabilities.auth is the highest-risk capability. A webhook response may assert a verified external identity with X-Kandev-Auth-Login; only assert an email the IdP verified as owned by the subject. See [ADR 0050](../decisions/0050-plugin-external-auth-capability.md). - Plugin installations also carry a host-minted opaque installation identity and a generic capability-approval ledger. That ledger records approval history, exact approval revisions, and revocation tombstones for the host boundary, but there is no public mutation UI in this release. Future exact Host adapters consume the approval receipt/query surface; they do not derive authority from plugin IDs, package digests, or workspace state. An isolated web app has a separate iframe and sandbox boundary. Kandev loads it same-origin with the host, so its trusted source can use the viewing user's ordinary browser authority, including cookies, storage, and the host DOM. It still cannot open popups or navigate the top-level page, and it receives no global Kandev JavaScript API. Capability URLs and grants remain required for Kandev protocol operations. See [Security and trust](security.md#isolated-web-applications) for the runtime boundary. ## Storage decision table | Need | Use | Scope/lifecycle | Capability or rule | | ----------------------------------------- | -------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------- | | Small JSON object owned by this plugin | Host state: GetState, SetState, DeleteState, ListState | instance, workspace, task, or agent; survives restart/upgrade and is included in Kandev state backups | capabilities.state: true; values are JSON objects, not bare scalars | | Canvas app shared state | Relative `./_kandev/v1/state` protocol | Canvas instance; survives restart while the instance remains | `state` grant, store app-specific shared values, not duplicate task data | | Per-user browser/plugin storage | host.storage: get/set/delete/list/subscribe | instance, workspace, task, session, or repository, scoped per user | capabilities.user_state: true; set/delete accept ifUnmodifiedSince and writerId | | Temporary canvas app value | JavaScript memory inside the iframe | Current document only | Use browser storage for user-scoped client data; keep shared app values in canvas state | | Operator configuration | Host.GetConfig and manifest config_schema | Plugin-owned settings; config changes restart an active subprocess | Ungated GetConfig; secret fields arrive cleartext in the subprocess | | Plugin-owned credentials | Host.GetSecret/SetSecret/DeleteSecret, or secret: true config fields | Encrypted Kandev vault, namespaced to this plugin | capabilities.secrets: true; never log values | | Files, caches, or plugin-managed database | KANDEV_PLUGIN_DATA_DIR | Shared across versions, removed on uninstall | Write only below the injected directory; own schema, locking, and migrations | Host state is not host.storage: Host state is plugin-scoped backend state with no transaction primitive, so design updates to be idempotent; host.storage (below) is per-user, per-scope frontend storage with an optional ifUnmodifiedSince compare-and-swap. `host.storage` belongs to the native plugin frontend contract. An isolated web app does not receive that API. Use the canvas state protocol instead. ## Authoritative contracts The guide summarizes the contract for discovery. These files remain the source of truth and must be updated together when the contract changes: - Versioned frontend author contract: `@kandev/plugin-sdk`, sourced from `apps/packages/plugin-sdk`. Import it with `import type`; the package has no dependency on Kandev, React, Zustand, or private `@/` modules, so it also typechecks when consumed from an isolated or sparse checkout. - Frontend host implementation: docs/plans/plugins/PLUGIN-API.md and apps/web/lib/plugins/types.ts. These may contain compatibility-only host details that are deliberately absent from the public SDK. - Concrete frontend Host exports: apps/web/lib/plugins/host-api.ts. - Backend author API: apps/backend/pkg/pluginsdk. - Wire contract: apps/backend/proto/kandev/plugin/v1/plugin.proto. - Manifest model and semantic validation: apps/backend/internal/plugins/manifest. - Package integrity and installation: apps/backend/internal/plugins/pkgtar. - Durable decisions: [ADR 0043](../decisions/0043-plugin-host-data-api.md), [ADR 0047](../decisions/0047-plugin-host-conversation-reads.md), [ADR 0048](../decisions/0048-plugin-host-utility-agent-invoke.md), [ADR 0050](../decisions/0050-plugin-external-auth-capability.md), [explicit plugin utility selection](../decisions/2026-09-14-explicit-plugin-utility-selection.md), and [Browser conversation facade ADR](../decisions/2026-09-06-browser-plugin-conversation-facade.md). The [source reconciliation design](../specs/plugins/system-design/conversation-source-reconciliation.md) defines the current storage and transport behavior. Requirements define observable behavior, and `PLUGIN-API.md` defines the browser API and Host-only v2 wire contract. ## Frontend contract ### Loading and cleanup The package's ui.bundle is a hand-written ES module. When active, Kandev loads it and the bundle calls: ```js window.registerKandevPlugin("my-plugin", { initialize(registry, host) {}, destroy() {}, }); ``` initialize receives a registry scoped to this plugin and a PluginHostApi. The host may call initialize more than once across disable/enable cycles. Make it repeatable; return a cleanup function from subscriptions and timers, and use destroy to remove side effects that are not registrations. The host revokes all registry entries, closes plugin modals, and removes plugin styles on disable/uninstall. Reloads can temporarily leave a plugin in a loading or failed state; open and saved panels remain until the current generation is ready. A ready generation that no longer registers a panel closes it, while an explicit disable or uninstall closes every panel owned by the plugin. This lifecycle bookkeeping is host-internal; plugins do not call lifecycle methods. Type frontend bundles against the versioned, runtime-free SDK rather than copying host interfaces or importing Kandev application files: ```ts import type { PluginHostApi, PluginRegistry } from "@kandev/plugin-sdk"; ``` Official code-host plugins use `host.context` for provider-neutral workspace, task-creation, and exact repository-identity reads. `getWorkspaceIds()` and `subscribeWorkspaces()` let a plugin republish workspace-scoped integration state after load or when the workspace list changes. If a required read is missing, extend this typed context contract; do not reverse-engineer Zustand slice shapes in a released plugin. Users configure a plugin's declared shortcuts on that installed plugin's detail page at **Settings > Plugins > ``**. These overrides are personal to the signed-in user. The plugin's schema-driven configuration and lifecycle controls remain install-wide and administrator-only. If a bundle registers a component at its exact plugin detail route, Kandev keeps that component and renders the host-owned shortcut card alongside it. Nested plugin settings routes remain fully plugin-owned. ### Browser conversation facade Native UI plugins read prompt history through `host.conversation`, not through `host.store`, raw WebSocket frames, first-party `/api/v1` URLs, or the Go Host reader. The facade requires `capabilities.api_read: ["messages"]`, and every manifest declaring that capability requires `min_kandev_version: "0.91.1"` or later. The same floor applies to Go `host.Messages().List` plugins. It returns sanitized public SDK DTOs. Inside a task panel, prefer the injected `conversation.history` handle so the read stays bound to that panel's task, session, and plugin generation: ```tsx function PromptHistory({ sessionId, conversation }: PluginTaskPanelProps) { const { messages, loading, loadMore } = conversation.history.useSessionMessages({ sessionId }); return ; ``` Panel handles are independently scoped and become inert on unmount, identity change, disable, or reload. `host.conversation` is the equivalent nearest-scope accessor; outside a panel it returns stable empty state. Use the canonical [PLUGIN-API contract](../plans/plugins/PLUGIN-API.md) for DTOs, pagination, revision-bound updates, lifecycle, recovery, and retryable errors. A complete source mutation sends a transient revision receipt after commit. An incomplete or uninstrumented mutation sends a reset marker, and the Host reads current source rows to repair the panel. The transport does not retain a payload journal or provide a replay guarantee. Browser route errors use `unauthenticated`/non-retryable for `401`, `not_found`/non-retryable for `404`, `invalid_query`/non-retryable for `400`, and `upstream_failure`/retryable for every authorized `5xx`. Within a task panel, omitted `taskId` inherits the panel task, explicit `null` reads the whole selected session, and an explicit task ID must match the panel task. `loadMore()` resolves to the number of newly projected messages; joined, exhausted, closed, and removed calls are deterministic, while transport failures reject with the typed error and preserve committed state. The turns hook follows the same scope and lifecycle rules, favorites remain read-only and reactive, and `session.removed` retains visible rows while closing future reads. | Need | Browser facade | Go Host API | | --- | --- | --- | | Surface | `host.conversation` or `conversation.history` | `host.Messages().List` | | Runtime | Native UI bundle | Plugin server process | | Data | Sanitized browser DTOs and revision-bound updates | Typed paginated reader | | Forbidden shortcut | `host.store`, raw WS, `/api/v1` | Private application imports | ### Frontend hook/API matrix | Surface | Location and input | Manifest requirement | Cleanup/lifecycle | Small example | | ------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- | | registerRoute | registry.registerRoute(path, Component, options?); exact SPA path; options.topbar defaults to host chrome or false for full-bleed | Active ui.bundle | Route is removed on disable/uninstall; use destroy for subscriptions | registry.registerRoute("/acme", Page, { topbar: { title: "Acme" } }) | | registerNavItem | { id, label, path, icon?, section? }; section is main, integrations, sidebar-footer (sidebar footer icon row, subject to an inline budget past which the item moves to the footer's overflow menu; and phone menu Utilities group, uncapped), or accepted-but-not-rendered settings | Active ui.bundle | Nav item is revoked and removed from desktop/phone navigation | registry.registerNavItem({ id: "home", label: "Acme", path: "/acme", icon: "chart" }) | | registerSettingsRoute | registerSettingsRoute(fullPath, Component) with an exact path under /settings/plugins//...; settings shell supplies chrome | Active ui.bundle | Route is removed on disable/uninstall | registry.registerSettingsRoute("/settings/plugins/acme/health", HealthPage) | | registerComponent | registerComponent(slot, Component); component receives { slotProps?: unknown } | Active ui.bundle | Every registration is owner-tracked, error-isolated, and bulk-revoked | registry.registerComponent("task-sidebar", Panel) | | registerWsHandler | registerWsHandler(action, handler(payload)); receives actions bridged from lib/ws | Active ui.bundle | Handler is removed on disable/uninstall; tolerate duplicate/replayed actions | registry.registerWsHandler("acme.updated", renderUpdate) | | registerKeybinding | registerKeybinding(id, handler(event)); id must be declared in ui.keybindings; users can override the effective combo on the installed plugin detail page at **Settings > Plugins > ``** | ui.bundle and ui.keybindings[] | Handler is removed on disable/uninstall; core shortcuts win, and editable targets are skipped unless that entry set ui.keybindings[].allow_in_editor | registry.registerKeybinding("open-panel", () => host.openModal(...)) | | registerIntegrationSettings | One provider-owned settings component with an optional action mounted in the detail header and the integrations index card | Active ui.bundle | Registration is exclusive by id and revoked on unload; host owns workspace selection and settings navigation; component and action receive the routed `workspaceId`, and action receives its `surface` | registry.registerIntegrationSettings({ id: "acme", Component, action: Toggle }) | | registerTranslations | Flat English fallback plus optional Kandev locale catalogs, isolated to this plugin's namespace | Active ui.bundle | Catalogs are replaced atomically, removed on unload, and registry consumers invalidate when the host locale changes | registry.registerTranslations({ en: { settings: "Settings" }, "pt-pt": { settings: "Definições" } }) | | registerRepositoryProvider | Provider-owned paged/searchable repository list, URL match/inspect, branches, and optional native `createChangeRequest` transport | ui.bundle and matching `repository_providers[]` id | Registration and in-flight callbacks are result-fenced on unload; host owns native task and Create PR UI | registry.registerRepositoryProvider({ id: "acme", ...provider }) | | registerTaskAction | Child action inside the task menu's native Link section | Active ui.bundle | Action is revoked on unload; host supplies current task/workspace and desktop/mobile presentation | registry.registerTaskAction({ id: "link-pr", placement: "link", ... }) | | registerReviewProvider | Normalized task reviews, workspace associations, unlink, and shared Review panel | ui.bundle and matching `repository_providers[]` id | Snapshots/subscriptions are owner-scoped and revoked on unload; host owns status chrome, indicators, unlink UI, and responsive Review placement | registry.registerReviewProvider({ id: "acme", ...reviews }) | | registerTaskPanel | { id, title, titleKey?, icon?, Component, mobileEnabled?, visible?(context) }; adds a row to the task workspace's "+" (add panel) menu; Component receives { panelId, taskId, sessionId, sessionKind, presentation, conversation: { openMessage(messageId), history } }; `titleKey` is a plugin translation key with literal `title` fallback | Active ui.bundle | Panel renders behind its own error boundary with reactive localized titles; a throwing `visible` hides the item; handles are generation-bound and independently scoped, inert after unmount, identity change, disable, reload, or uninstall; `host.conversation` outside a panel returns stable empty state; desktop preserves layout identity on navigation and mobile uses the full-height Chat surface | registry.registerTaskPanel({ id: "notes", title: "Notes", titleKey: "panels.notes", Component: NotesPanel }) | | registerTaskMenuAction | { id, label, icon?, group: "edit" \| "primary", visible?(context), items?(context), run(context) }; "edit" is card-only inside Edit, while "primary" is a top-level item on cards and desktop/mobile task-row menus; a synchronous `items(context)` returning TaskMenuSubItemRegistration[] ({ id, label, icon?, disabled?, run(context) }) renders the action as a submenu of those children instead | Active ui.bundle | Action is revoked on disable/uninstall; a throwing/rejecting run is caught and logged; an items() that throws or yields nothing usable falls back to the flat item, and unusable children are dropped | registry.registerTaskMenuAction({ id: "enhance", label: "Enhance", group: "primary", run: doEnhance }) | | registerTaskFilter | { id, label, getOptions(), matches(context, selected) }; adds a client-side, multi-select filter section to the kanban board's display dropdown, alongside Workflow/Repository | Active ui.bundle | Filter is revoked on disable/uninstall; selections are ephemeral (not persisted); matches is only called for a non-empty selection, and a throw is caught, logged, and treated as non-matching | registry.registerTaskFilter({ id: "tags", label: "Tags", getOptions: listTagOptions, matches: taskHasSelectedTag }) | | registerTaskListFacet | { id, label, getValues({ taskId, workspaceId }), subscribe? }; adds page-local Sort and Group choices on `/tasks` | Active ui.bundle | Values apply only to the loaded page, callbacks are isolated, and registrations are revoked on disable/unload | registry.registerTaskListFacet({ id: "tags", label: "Tag", getValues: taskTags }) | | host.React / host.jsx | Shared React instance and React.createElement alias | Active ui.bundle | No cleanup; never bundle a second React/Radix runtime | const h = host.jsx | | host.context | Versioned provider-neutral reads/subscriptions for active workspace, all workspace ids, native task creation, and exact provider repository identity | Active ui.bundle | Subscriptions are generation-owned and revoked on unload; records are stable SDK shapes, not private app state | const ids = host.context.getWorkspaceIds() | | host.useSettingsSaveContributor | Registers one plugin-owned contributor for the native save bar; the host prefixes ids with `plugin::` before shared coordination | Active ui.bundle | Contributor lifecycle follows the rendering component; save and discard remain plugin-owned | host.useSettingsSaveContributor({ id: "credentials", revision, isDirty, save, discard }) | | host.setIntegrationEnabled | Publishes one registration's live enabled value for one workspace; the value is reactive but not durable | Active ui.bundle | The host validates that `integrationId` belongs to this plugin; republish after load using `host.context.getWorkspaceIds()` and `subscribeWorkspaces()` | host.setIntegrationEnabled("acme", workspaceId, enabled) | | host.i18n | Plugin-scoped `locale`, imperative `t(key, options?)`, and reactive `useTranslation()` | A registered English catalog | Locale changes re-render reactive consumers; missing active-locale messages fall back to the plugin's English catalog | const { t } = host.i18n.useTranslation(); t("pullRequests") | | host.store (legacy) | Compatibility-only access to Kandev's private Zustand store; intentionally absent from `@kandev/plugin-sdk` | Older ui.bundle | Do not use in new or official plugins; private slices may change without plugin-API compatibility | Migrate reads to host.context | | host.api.fetch / baseUrl | fetch(path, init?) is scoped to /api/plugins//...; baseUrl is the backend origin for split-origin deployments | Active ui.bundle; backend path must be a declared webhook when relayed | Declare `webhooks[].access: authenticated` for UI-only or billable operations; requests are generation-aborted on unload | host.api.fetch("webhooks/inbound", { method: "POST" }) | | host.api.invokeAction | Authenticated call to a declared action with host-verified workspace/task/session/repository selectors and bounded untrusted body | Matching manifest `actions[]` key/scope | Browser abort cancels the bounded plugin RPC; safe domain statuses and `Retry-After` may be returned | host.api.invokeAction("reviews.get", { taskId }, { signal }) | | host.storage | Authenticated, per-user key/value storage: get(scope, scopeId, key, options?)/set(scope, scopeId, key, value, options?)/delete(scope, scopeId, key, options?)/list(scope, scopeId, options?) plus subscribe(filter, handler); no plugin backend required | capabilities.user_state: true | Reads and writes accept an AbortSignal; set/delete also accept writerId (appended to the host's per-tab id, not a replacement) for echo suppression; list returns every entry under the scope pair, unpaginated | host.storage.set("task", taskId, "note", value, { writerId: panelId, signal }) | | host.ui | Curated host instances: Alert*, Badge, Button, Card*, Checkbox, Dialog*, DropdownMenu*, Input, Label, Pagination*, ScrollArea, Select*, Separator, Sheet*, Skeleton, Spinner, Switch, Table*, Tabs*, Textarea, Tooltip*, RichTextEditor, RichTextReadOnly, plus Combobox, PageTopbar, TaskCreateDialog | Active ui.bundle | Host owns contexts/portals; render with host React and let modal/slot cleanup run | const Button = host.ui.Button | | host.theme | Current "light" or "dark" theme | Active ui.bundle | Read during render; subscribe through host/app patterns if theme-sensitive | host.theme === "dark" | | host.navigate | Soft SPA navigation navigate(href, { replace? }) | Active ui.bundle | No registry cleanup; avoid navigating to undeclared external origins | host.navigate("/t/" + taskId) | | host.openModal | Host-owned modal: { title?, content, size?, dismissible? } -> { close() } | Active ui.bundle | Modal auto-closes on disable/uninstall; close handles are idempotent | const modal = host.openModal({ content: Panel }) | ### Code-host integration surface map A code-host plugin should be a normalized provider adapter, not a parallel copy of Kandev's GitHub UI. The plugin owns remote API calls, authentication, provider identifiers, and normalized snapshots. Kandev owns the interaction patterns, responsive layout, status colors, dialogs, menus, and review chrome. | User-facing result | Plugin hook | Plugin supplies | Kandev supplies | | -------------------------------------- | -------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------- | | Provider workbench | `registerRoute`, `registerNavItem`, and host dashboard primitives | Query state, normalized rows, opaque cursors, refresh and launch callbacks | Page chrome, searchable repository filter, cursor pagination, saved-query dialog, list rows, task preset menu, desktop/mobile primitives | | Workspace connection settings | `registerIntegrationSettings` | Provider-specific fields, health checks, connect/disconnect behavior | Settings navigation, active workspace, lifecycle and error boundary | | Native repository and branch selection | `registerRepositoryProvider` plus declared branch action | Credential-free repositories, branches, URL inspection, optional `createChangeRequest` transport | Existing task dialog, provider picker, branch picker, push-before-create flow | | Task-to-review linking | `registerTaskAction` and `host.openTaskLinkDialog` | Provider label/icon, accepted reference syntax, authenticated link callback | Existing **Link** submenu, dialog validation, submit state, toast and desktop/mobile presentation | | Task indicators, CI, unlink and review | `registerReviewProvider` | Association snapshots, semantic `taskStatus`, normalized review detail, refresh/unlink callbacks | Sidebar/Kanban indicators, status palette, 90-second refresh, topbar/composer status, unlink UI and shared Review panel | | Composer `#` search | Manifest `reference_sources`, `SearchEntityReferences`, and `AuthorizeEntityReference` | Display candidates and a fresh provider authorization at submission | Source menu, chips, canonical metadata and fail-closed submission | | Authenticated browser operations | Manifest `actions` and `host.api.invokeAction` | Bounded action handler using verified context | Actor/resource authorization, selector stripping, timeout, cancellation and response limits | The task indicator uses the same semantic precedence as first-party providers: failures and requested changes are red, pending checks yellow, an outstanding review with passing checks sky blue, passing checks green, merged reviews purple, and neutral or draft reviews muted. Publish semantic state only; never send CSS classes or provider-selected colors. Persist links, suppressions, task reservations, and watches by provider ID, provider connection scope, immutable repository ID, and change-request number. Repository names, paths, clone URLs, and human-readable review keys can change or be reused, so use them only for display and live lookup. Bind watch state and OAuth refresh work to an opaque connection epoch; replacement or disconnect must fence in-flight results, while an explicit resume may bind a watch to the new epoch. Keep `refresh(taskId)` lightweight: publish metadata, reviewers, checks, and an inexpensive comment count when available. Load files, diffs, commits, and comment bodies from `ReviewPanel` only when the user opens Review. Bound every provider page and action response, and expose truncation rather than overflowing Kandev's response limit. Repository listing callbacks receive optional `query`, opaque `cursor`, `limit`, and `signal` fields. Return `{ repositories, nextCursor }` for a page; returning an array remains compatible for small or older providers. Treat cursors as provider-owned opaque values, bind them to the original query, and stop emitting `nextCursor` when exhausted. Include immutable repository identity and provider connection scope in that binding; reject a mismatched cursor before making a remote request. Kandev follows pages and fails a repeated cursor instead of looping forever. ### Localize plugin UI Register an English fallback before registering labels or rendering routes. Catalogs are flat, plugin-scoped, and support `{{name}}` interpolation plus `_one`/`_other` plural keys. Use the reactive hook in components and the imperative translator in registry getters so a locale change updates native navigation and provider labels without reloading the plugin. ```ts registry.registerTranslations({ en: { pullRequests: "Pull requests", linkedCount_one: "{{count}} pull request linked", linkedCount_other: "{{count}} pull requests linked", }, "pt-pt": { pullRequests: "Pull requests", linkedCount_one: "{{count}} pull request associado", linkedCount_other: "{{count}} pull requests associados", }, }); const translate = host.i18n.t; registry.registerNavItem({ id: "reviews", get label() { return translate("pullRequests"); }, path: "/reviews", }); function ReviewsPage() { const { t } = host.i18n.useTranslation(); return host.jsx("h1", null, t("pullRequests")); } ``` ### Own provider brand icons Icon fields accept a curated host icon name or a plugin-owned component. Keep provider brands in the plugin repository so a new code host does not require a Kandev icon-map change. Build the component with `host.jsx`; do not bundle React. ```ts const AcmeIcon = ({ className }: { className?: string }) => host.jsx( "svg", { viewBox: "0 0 24 24", className, "aria-hidden": true }, host.jsx("path", { d: "M4 12h16" }), ); registry.registerRepositoryProvider({ id: "acme", label: "Acme", icon: AcmeIcon, // listRepositories, listBranches, and inspectURL omitted here }); ``` Kandev accepts only supported host locale IDs, at most 1,000 messages per locale, safe flat keys, and messages up to 4,096 characters. An invalid replacement is rejected before the active catalog changes. Do not translate provider identifiers, action keys, URL paths, or other machine-readable state. For a plugin-owned workbench, use `host.ui.IntegrationRepositoryFilter` and `host.ui.IntegrationCursorPagination`; they preserve the same searchable picker, pagination geometry, touch targets, and responsive behavior as first-party code-host pages without requiring a plugin to copy their markup. The examples below were captured from an isolated packaged-plugin run. The provider data is fictional; the surrounding controls are the production host-owned components. #### Provider dashboard and repository picker The plugin route composes the shared dashboard primitives, while the declared repository provider appears inside Kandev's existing task dialog. ![A plugin-provided pull-request dashboard using Kandev's shared scope tabs, repository filter, query field, saved-query control, refresh action, and change-request row.](../screenshots/plugin-code-host-dashboard.png) ![Kandev's native task dialog showing a repository supplied by a plugin repository provider in the Remote picker.](../screenshots/plugin-code-host-repository-picker.png) #### Link a pull request from a task `registerTaskAction` contributes only the provider entry. The host owns the parent **Link** menu and the link dialog. ![A task context menu with its Link submenu open, showing GitHub, GitLab, and Bitbucket targets in the shared host layout with provider-owned brand icons.](../screenshots/plugin-code-host-link-menu.png) ![The host-owned Link Bitbucket pull request dialog with provider copy, one reference field, and the standard Cancel and Save actions.](../screenshots/plugin-code-host-link-dialog.png) #### Task status, CI, and review Association and review snapshots drive every surface. In this example, passing CI plus one outstanding reviewer makes the task icon sky blue; hovering it shows the same normalized summary used by first-party providers. ![A sky-blue pull-request icon beside a task and its hover summary showing PR number, title, approved review, and passing CI.](../screenshots/plugin-code-host-sidebar-status.png) ![The host-owned composer CI popover showing two passing checks, review state, an unresolved comment, and refresh and unlink controls.](../screenshots/plugin-code-host-ci-popover.png) ![The shared Review panel rendering normalized pull-request metadata, review state, CI checks, threaded comments, and provider-advertised actions.](../screenshots/plugin-code-host-review-panel.png) #### Composer reference search Dynamic `reference_sources` appear beside built-in sources. A selected result is display-only until Kandev calls the plugin again to authorize it for submission. ![The composer reference picker showing a Bitbucket pull-request result for a hash search query.](../screenshots/plugin-code-host-reference-search.png) ### Supported named slots registerComponent currently has these mounted slots. The source type is open to strings, but an unmounted name renders nowhere. | Slot | Mounted location | slotProps | | ------------------------- | ------------------------------------------------------------------------------------------ | ---------------------------------------------------------------- | | task-sidebar | Bottom of task-detail sidebar | none | | settings-nav | Settings navigation tree | none | | chat-input-actions | Task or Quick Chat composer toolbar | PluginComposerSlotProps | | task-create-input-actions | Task creation composer toolbar | PluginComposerSlotProps | | new-session-input-actions | New-session composer toolbar | PluginComposerSlotProps | | chat-submit-decoration | Layer over the composer's send button | ChatSubmitDecorationSlotProps | | chat-top-bar | Session top bar or phone Plugins menu | ChatTopBarSlotProps | | main-top-bar | Home/Kanban/Tasks top bar or phone Plugins menu | MainTopBarSlotProps | | app-status-bar-left | Left side of desktop status bar or mobile status drawer | AppStatusBarSlotProps | | app-status-bar-right | Right side of desktop status bar or mobile status drawer | AppStatusBarSlotProps | | plugin-settings | Top of this plugin's Settings > Plugins page | { pluginId, status }; owner-scoped to the plugin being viewed | | task-card-indicators | Kanban card, beside the PR status icon | { taskId, workspaceId, workflowStepId } | | task-card-tags | Kanban card, its own row below the badges row | { taskId, workspaceId, workflowStepId } | | task-row-metadata | Sidebar task tree and `/tasks` rows | TaskRowMetadataSlotProps | | sidebar-workspace-actions | Desktop New Task row or phone navigation action group, after Quick Terminal and Quick Chat | SidebarWorkspaceActionsSlotProps | AppStatusBarSlotProps is { placement, presentation, density, pathname, activeWorkspaceId, activeTaskId, activeSessionId }. Desktop presentation is a compact 24px bar; mobile presentation is an in-flow drawer, so render a touch-usable row. Status items can be reordered by the host; plugins do not get an ordering API. `SidebarWorkspaceActionsSlotProps` is `{ workspaceId, workspaceLabel?, presentation }`. The host uses `presentation: "desktop"` for the compact sidebar cluster and `presentation: "mobile"` for the phone navigation sheet. Mobile actions must keep their own buttons or links at least 44px in the active dimension and provide an accessible name. `PluginComposerSlotProps` is `{ surface, presentation, taskId, taskTitle?, activeSessionId, sessionIds, disabled, submittable, disabledReason?, composer }`. The `composer` capability provides `insertText`, `focus`, and asynchronous `submit`; submit returns `submitted` only when the native composer accepts the operation, otherwise `blocked` or `unavailable`. ## Backend contract ### Plugin lifecycle surface | Surface | Input/output | Manifest capability or declaration | Lifecycle/cleanup | Example | | -------------------- | --------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------- | | Plugin.OnEvent | OnEvent(ctx, \*pluginsdk.Event) error; event has EventID, EventType, OccurredAt, WorkspaceID, Payload | Matching capabilities.events subject/pattern | Delivery is sequential per plugin with bounded queue and retries; make handlers idempotent by EventID and reconcile critical state | if event.EventType == "task.created" { ... } | | Plugin.HandleWebhook | HandleWebhook(ctx, *pluginsdk.WebhookRequest) (*WebhookResponse, error); request includes key, method, path, query, headers, body | webhooks[].key; auth additionally required for login assertion header | Undeclared keys are 404; GET/POST are relayed; validate method/signature and bound side effects | if req.WebhookKey == "inbound" { ... } | | Host.EmitEvent | EmitEvent(ctx, name, payload) publishes plugin.. | None; intentionally ungated | Subscribers must declare the emitted subject; use versioned names/payloads | host.EmitEvent(ctx, "sync.completed", payload-map) | Event delivery is best-effort: Kandev makes the initial attempt plus retries with 5s, 15s, and 45s delays, and a bounded in-memory queue/error buffer can drop events during sustained overload or restart. Use EventID for deduplication and a source-of-truth reconciliation path when loss matters. The full subscription vocabulary and wildcard rules are in the [manifest reference](plugins-manifest.md#event-subscription-vocabulary). ### Host API matrix | Host surface | Methods | Required manifest capability | Notes | | --------------------- | ------------------------------------------------------------------------------ | --------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | State | GetState, SetState, DeleteState, ListState | state: true | Plugin-scoped JSON objects keyed by scope/scopeID/key; no transactions | | Config | GetConfig | None | Reads this plugin's validated config_schema; secret fields are cleartext in the subprocess; config updates restart active plugins | | Secrets | RevealSecret, GetSecret, SetSecret, DeleteSecret | secrets: true | Encrypted vault; plugin-owned keys are namespaced; never log values | | Tasks | Tasks().List, Tasks().Get | api_read: tasks | Typed DTOs and opaque pagination cursor | | Tasks writes | Tasks().Create, Tasks().Update, Tasks().Move | api_write: tasks | Implemented; routed through Kandev services so events/WS updates fire. Create and Update support priority. Update rejects a workflow step change; Move is the only path that moves a task between steps | | Sessions | Sessions().List, Sessions().CodeStats | api_read: sessions | Typed session and computed code-stat records | | Workspaces | Workspaces().List | api_read: workspaces | Instance-visible workspaces | | Workflows | Workflows().List, Workflows().ListSteps | api_read: workflows | List steps by workflow id | | Agent profiles | AgentProfiles().List | api_read: agent_profiles | Global agent profiles exposed by the Host data API | | Repositories | Repositories().List | api_read: repositories | List by workspace id | | Messages | Messages().List | api_read: messages | Historical user/agent content; Kandev system blocks are stripped | | Message send | Messages().Send | api_write: messages | Sends a prompt to a task session and records plugin: author | | Interactions | Interactions().ListPending, Interactions().Get | api_read: interactions | Durable record of agent requests still owed a human answer; Get resolves resolved ones too | | Interaction responses | Interactions().RespondToPermission, .AnswerClarification, .CancelClarification | api_write: interactions | Routed through the services the native UI drives; first terminal response wins | | Agent invocation | InvokeUtilityAgent(ctx, prompt, options...) | agent_invoke: true | One-shot completion. No options, or an empty ProfileID, uses the current platform default. A non-empty ProfileID selects that exact eligible profile. An invalid explicit profile returns FailedPrecondition without fallback. The host does not read plugin configuration for selection. | | Agent conversations | AgentConversations(host): Ensure, Dispatch, Delete | agent_conversation: true | Hidden workflowless ephemeral task/session per plugin, workspace, and conversation key; dispatch occurrence keys are durable and idempotent; uninstall removes every conversation owned by the plugin | The Go signatures, filters, DTOs, and pagination types live in apps/backend/pkg/pluginsdk/host.go and data_types.go. api_write task/message methods are implemented in the current branch; do not repeat older docs that call them reserved. Host calls are request-scoped rather than registrations: pass the handler context, handle cancellation, and close any files or external clients created by the plugin. There is no Host cleanup callback. Typical calls are `host.SetState(ctx, "task", taskID, "note", value)`, `host.Tasks().List(ctx, filter, page)`, `host.Tasks().Create(ctx, pluginsdk.CreateTaskInput{...})`, `host.Messages().Send(ctx, taskID, sessionID, text)`, and `host.InvokeUtilityAgent(ctx, prompt)`; each fails with `PermissionDenied` when its manifest capability is absent. ## Task-oriented recipes The snippets below are deliberately small. Keep the full template Makefile and release workflow from the official scaffold. The maintained in-tree fixture shows the same surfaces end to end: its [Go backend](../../apps/backend/cmd/plugin-fixture/plugin.go), [manifest](../../apps/backend/cmd/plugin-fixture/fixture-package/manifest.yaml), and [native bundle](../../apps/backend/cmd/plugin-fixture/fixture-package/ui/bundle.js) are the source examples used by the package and browser tests. ### 1. UI-focused plugin Use a no-op backend because the managed installer requires a host executable. ```yaml # manifest.yaml id: "acme-dashboard" api_version: 1 version: "0.1.0" display_name: "Acme Dashboard" runtime: type: binary executables: linux-amd64: server/plugin-linux-amd64 ui: bundle: "/ui/bundle.js" ``` ```go // server/main.go package main import "github.com/kandev/kandev/pkg/pluginsdk" func main() { pluginsdk.Serve(&pluginsdk.UnimplementedPlugin{}) } ``` ```js // ui/bundle.js window.registerKandevPlugin("acme-dashboard", { initialize(registry, host) { function Page() { return host.jsx("main", null, "Acme dashboard"); } registry.registerRoute("/acme-dashboard", Page); registry.registerNavItem({ id: "home", label: "Acme", path: "/acme-dashboard", icon: "chart", }); }, }); ``` ### 2. Go backend with Host state ```go type Plugin interface { // OnEvent handles a single bus event delivery. A non-nil error causes // kandev to retry (3 retries, 5s/15s/45s backoff). OnEvent(ctx context.Context, e *Event) error // HandleWebhook handles an inbound request relayed from // POST /api/plugins/{id}/webhooks/{key}. HandleWebhook(ctx context.Context, req *WebhookRequest) (*WebhookResponse, error) } ``` Embed `pluginsdk.UnimplementedPlugin` and override only the methods you need It is a no-op base that also implements `HostSetter`, so `Serve` injects a live `Host` into your plugin once the broker connection back to kandev is established (retrieve it later via `p.Host()`). ## Webhooks Declare each webhook key in `manifest.yaml`. Kandev relays `GET` and `POST` requests for `/api/plugins//webhooks/` to `HandleWebhook`; undeclared keys return `404`. Request bodies are limited to **4 MiB** and requests that exceed the limit return `413` before reaching the plugin. Kandev does not authenticate webhook callers or enforce the manifest's informational `method`, so validate the HTTP method and the upstream provider's signature before any side effect. ## The Host API A plugin calls back into kandev through the injected `Host`: ```go type UtilityAgentOptions struct { ProfileID string } type Host interface { GetState(ctx context.Context, scope, scopeID, key string) (value map[string]any, found bool, err error) SetState(ctx context.Context, scope, scopeID, key string, value map[string]any) error DeleteState(ctx context.Context, scope, scopeID, key string) error ListState(ctx context.Context, scope, scopeID string) ([]StateEntry, error) // GetConfig returns the plugin's own operator-editable config (set via // Settings > Plugins > , generated from manifest config_schema). // Ungated: always readable, secret values included. Kandev restarts a // running plugin when its config changes, so re-read at startup. GetConfig(ctx context.Context) (map[string]any, error) // GetSecret/SetSecret/DeleteSecret manage a plugin-owned secret in // kandev's encrypted vault, namespaced to this plugin. Require the // `secrets` capability. GetSecret(ctx context.Context, key string) (value string, found bool, err error) SetSecret(ctx context.Context, key, value string) error DeleteSecret(ctx context.Context, key string) error // RevealSecret resolves an operator-provided secret reference (e.g. a // config value pointing at a shared kandev secret) to its cleartext // value. For secrets the plugin itself owns, use GetSecret/SetSecret. RevealSecret(ctx context.Context, ref string) (string, error) EmitEvent(ctx context.Context, name string, payload map[string]any) error // Tasks/Sessions/Workspaces/Workflows/AgentProfiles/Repositories return // Host data accessors. List/Get operations require their own api_read // resource; task Create/Update/Move require api_write:tasks. Tasks() TaskReader Sessions() SessionReader Workspaces() WorkspaceReader Workflows() WorkflowReader AgentProfiles() AgentProfileReader Repositories() RepositoryReader // Messages.List reads historical content (api_read:messages); Send // delivers a user prompt through the task session (api_write:messages). Messages() MessageReader // InvokeUtilityAgent runs a one-shot completion. No options uses the // platform default. UtilityAgentOptions.ProfileID selects one eligible // profile for this call (capability agent_invoke). InvokeUtilityAgent(ctx context.Context, prompt string, options ...UtilityAgentOptions) (string, error) } ``` Executor profiles are an additive, optional Host extension so older Host implementations remain source-compatible. Discover it through the SDK helper: ```go profiles, ok := pluginsdk.ExecutorProfiles(host) if ok { items, page, err := profiles.List(ctx, pluginsdk.Page{}) // handle items, page, and err } ``` Declare `api_read: ["executor_profiles"]` before using this reader. A host that does not implement the extension returns `ok == false`; an implemented reader without the capability returns `PermissionDenied` from `List`. Pending agent interactions are an additive, optional Host extension too; discover it the same way with `pluginsdk.Interactions(host)`. See "Pending agent interactions" below for the contract. Managed agent conversations are another optional Host extension. They let a backend plugin keep one hidden agent session for each workspace and stable conversation key: ```go conversations, ok := pluginsdk.AgentConversations(host) if !ok { return errors.New("this Kandev host does not support agent conversations") } descriptor, status, err := conversations.Ensure(ctx, pluginsdk.AgentConversationSpec{ WorkspaceID: workspaceID, ConversationKey: "coordinator", BasePrompt: "Review this workspace and report actionable changes.", AgentProfileID: configuredProfileID, }) ``` Declare `agent_conversation: true` before using the manager. `Ensure` returns `created`, `exists`, or `configuration_required`; the last result creates no task or session. `Dispatch` returns `started`, `sent`, `duplicate_occurrence`, or `skipped_busy`. Supply a stable occurrence key when a scheduled event may be retried; a busy dispatch does not consume it. `Delete` is idempotent and only removes conversations owned by the calling plugin. Disabling or uninstalling the plugin removes all of that plugin's managed conversations across workspaces. **Host state** is a small key/value store kandev keeps for your plugin in its own database. Each entry is addressed by a `(scope, scopeID, key)` triple and holds a JSON object (`map[string]any`): `SetState` upserts one, `GetState` reads it back (`found` is `false` when the key was never set), `DeleteState` removes it, and `ListState` returns every entry under a `(scope, scopeID)`. Values are JSON objects, not bare scalars; wrap a number as `map[string]any{"n": 3}`. State is namespaced per plugin (kandev injects your plugin id server-side, so no plugin can read or write another's), survives restarts, is captured by kandev's database backups, and is deleted when the plugin is uninstalled. Reach for it when you want kandev to durably remember something small and structured for you; use the writable data directory below for arbitrary files you'd rather manage yourself. `scope` partitions that store by what a value belongs to: `instance` (the whole kandev instance; `scopeID` empty), or `workspace` / `task` / `agent` with `scopeID` set to that entity's id. A per-task counter, for example, is `SetState(ctx, "task", taskID, "count", map[string]any{"n": 3})`; kept separate from every other task's. `EmitEvent` publishes `plugin..` on kandev's internal event bus for delivery to any subscriber (including other plugins). The data-reader accessors return typed, paginated readers, for example `host.Tasks().List(ctx, TaskFilter{...}, Page{Limit: 50})` returns `([]Task, *PageInfo, error)` with an opaque `PageInfo.NextCursor` for the next page. See `pkg/pluginsdk/data_types.go` for the full `Task`, `Workspace`, `Workflow`, `WorkflowStep`, `AgentProfile`, `Repository`, `Session`, `Message`, and filter/page types. #### Task dependencies Every `Task` returned by `host.Tasks().Get`/`.List` carries a read-only dependency projection: `Blocked`, `BlockedReason`, `DependsOn`, `Blocks`, `DependsOnTruncated`, `BlocksTruncated`, and `StartWhenUnblocked`. `DependsOn` and `Blocks` are `[]TaskDependencyRef` (`ID`, `Title`, `State`, `Status`; `Status` is only ever set on a `DependsOn` entry, since a task cannot be "pending" or "resolved" against a task it blocks). Each list is capped at 512 entries; the matching `*Truncated` flag reports whether more edges exist than were returned. A gRPC plugin sees no redaction: every edge end's `Title` and `State` are populated regardless of which workspace it belongs to, unlike the canvas surface described in [`canvases.md`](canvases.md), which blanks both fields for an edge end the caller's canvas scope does not directly admit: a workspace-scoped canvas admits an end sharing its workspace, a repository- or session-scoped canvas admits an end only when it is also returned as a directly readable task in the same response, and a task-scoped canvas admits none. If dependency derivation cannot produce a verdict for a task that a call does return, the host substitutes the withheld verdict rather than failing that call: `Blocked: true`, `BlockedReason: "unknown"`, empty `DependsOn`/`Blocks`, both truncation flags `false`, and `StartWhenUnblocked: false`. Treat this shape as "no answer," not as "task is actually blocked." Two distinct causes reach it: an internal read failure during derivation, or a task reached through `CreateTask`/`UpdateTask`/ `MoveTask` by a caller holding `api_write:tasks` but not `api_read:tasks` (an independent capability those RPCs gate on writing, not reading). `List` and `Get` themselves never produce this verdict for a missing read capability: each fails the call outright with `PermissionDenied` before any task is returned, so accessor denial and a withheld verdict on a returned task are never the same signal. This is also distinct from the fan-out limit below: that refuses the whole call with `ResourceExhausted` rather than substituting a withheld verdict onto any task. Canvas event payloads do not carry the dependency projection: `Blocked`, `BlockedReason`, `DependsOn`, `Blocks`, the truncation flags, and `StartWhenUnblocked` are refetch-on-signal fields for the canvas surface. Native plugin `OnEvent` deliveries can carry the four dependency fields (`blocked`, `blocked_reason`, `depends_on`, and `blocks`) on dependency-related `task.updated` events. The truncation flags and `start_when_unblocked` still come from `host.Tasks().Get`/`.List`, so an event is never a complete replacement for a task read. A plugin that caches a task's dependency fields refetches them when: a `task.updated` event names that task or either end of one of its edges; a `task.dependencies_resolved` or `task.dependency_failed` event names that task; or a `task.state_changed` event names any task ID present in that task's cached `DependsOn` or `Blocks` list, since a predecessor or dependent simply advancing state is not itself one of the first three signals. A single `Get`/`List` response is not a transactional snapshot: with no surrounding lock, an edge can change while the read is being derived, so one response can show an edge asymmetrically (for example, a predecessor still listed as pending after it has already resolved). Treat what a response returns as the union of independently-read facts, and resolve staleness by refetching on the next matching signal rather than trusting any single response as authoritative. Reading dependencies adds no extra query per task; the host derives them for the whole page in one batched pass. That batch is bounded by a fixed limit on the number of distinct task IDs it will read across all edges on the page: whether an edge is expressed once or shared by many tasks, each distinct ID only counts once toward the limit. `ListTasks` and the plugin-owned task-tree preview RPC (`PreviewPluginOwnedTaskTree`) are both bound by this limit and fail the call with a `ResourceExhausted` error when a page (or, for the preview RPC, the tree itself) would cross it; the preview RPC accepts no page `limit` at all, so the only remedy is asking for a smaller tree. Flows that always return exactly one task, `GetTask` and the task-write RPCs (`CreateTask`, `UpdateTask`, `MoveTask`), can never exceed the limit and are exempt. A `ResourceExhausted` response is about the cost of deriving the answer, not about the size of the reply; it is never folded into the withheld verdict. `ListTasks`'s `Page.Limit` clamps only its upper bound: a limit above the host's page ceiling is lowered to that ceiling, and a limit at or below zero (including an unset, proto3-default zero) falls back to the host's default page size. That default is the largest page the endpoint will return on its own, so retrying a rejected call with a smaller explicit `Limit` (not with a zero or negative one) is the way to shrink a page that tripped the fan-out limit above. Declare a `min_kandev_version` manifest floor for the first Kandev release your plugin expects to carry these seven fields; a host older than that floor omits them from the wire message entirely (the SDK reports them as their zero values, indistinguishable from "not blocked, no edges"). This floor is a single host-wide capability check performed once at install time: it does not name `task-dependencies` or any other capability, unlike the capability-keyed `min_kandev_version` requirement on `api_read:messages` described above, which the host re-validates per declared capability. A dev or otherwise non-release build of the host always satisfies the floor check regardless of its actual age, so a plugin installed on such a build can still receive the same ambiguous zero-value bytes; do not rely on the floor check alone as proof the fields are populated when running against a non-release host. `host.Messages().List(ctx, MessageFilter{...}, Page{...})` reads historical conversation content (capability `api_read:messages`). Filter by `SessionIDs`, `TaskIDs`, a `Since`/`Until` `created_at` window (RFC3339; `Since` inclusive, `Until` exclusive, the natural way to fetch "yesterday"), and message `Types`. Each `Message` carries `id`, `session_id`, `task_id`, `turn_id`, `author_type` (`user` or `agent`), `content`, `type`, and `created_at`. `content` has kandev's injected `` blocks stripped; a plugin never sees raw system prompts. ### Pending agent interactions An agent sometimes stops and waits for a person: a tool-permission request, or a structured question bundle. If your plugin surfaces attention (an inbox, a notifier, a dashboard badge), read that from the interaction API rather than from session state. `WAITING_FOR_INPUT` also describes an ordinarily completed turn, so a plugin that branches on state alone tells people they owe an answer they do not. ```go interactions, ok := pluginsdk.Interactions(host) if !ok { // Host predates the interaction API. return nil } pending, _, err := interactions.ListPending(ctx, pluginsdk.InteractionFilter{ TaskIDs: []string{taskID}, }, pluginsdk.Page{Limit: 50}) ``` Each `Interaction` carries `ID` (the pending id every response keys on), `Kind` (`permission` or `clarification`), the task, session and turn ids, a normalized `Status`, timestamps, and everything needed to render a valid response: `Options` for a permission, `Questions` (each with its own options) for a clarification bundle. `AgentDisconnected` marks a still-pending clarification whose original waiter went away; it remains answerable, and answering it resumes the session in a new turn, so do not treat it as resolved. `Interactions().Get(ctx, id)` resolves any interaction, including resolved ones. That is how an event-driven cache reconciles: an id from an event you replayed or a snapshot you took before a restart still resolves to its current state instead of vanishing. Responding requires `api_write: ["interactions"]` and goes through the same services the native UI drives, so the agent actually unblocks: ```go _, err := interactions.RespondToPermission(ctx, pluginsdk.PermissionResponse{ InteractionID: interaction.ID, OptionID: interaction.Options[0].OptionID, }) ``` `OptionID` must name one of the interaction's declared options; Kandev derives the approve/deny outcome from that option's `Kind`, so you cannot report an outcome the agent never offered. Set `Cancelled: true` (with an empty `OptionID`) to dismiss the request instead. `AnswerClarification` takes one answer per question in the bundle; `CancelClarification(ctx, id, reason)` declines the bundle on the user's behalf and works whether or not the original waiter is still parked. Writes are terminal-once. The first response wins; a later attempt against an already-resolved interaction returns gRPC `FailedPrecondition`, and an unknown id returns `NotFound`. Branch on those two to tell "someone else answered first" apart from "my cached id is stale". Do not retry a `FailedPrecondition`. `host.InvokeUtilityAgent(ctx, prompt)` runs a one-shot, non-interactive LLM completion using the platform default profile configured in **Settings > Utility Agents** (capability `agent_invoke`), and returns its text. A plugin can pass an explicit profile for one call: ```go text, err := host.InvokeUtilityAgent(ctx, prompt, pluginsdk.UtilityAgentOptions{ ProfileID: savedProfileID, }) ``` The plugin owns persistence of `savedProfileID`. An empty or unset preference should omit the override or pass an empty ProfileID. The host does not inspect the plugin's configuration to choose a profile. Declare an optional profile field when the plugin wants the standard Settings picker: ```yaml capabilities: agent_invoke: true config_schema: type: object properties: agent_profile: type: string format: agent-profile title: Utility agent profile description: Optional profile used for this plugin's LLM calls ``` The picker displays eligible global agent profiles and stores the selected profile's stable ID. The field is ordinary plugin configuration; read it with `host.GetConfig` and pass the value explicitly. A missing, deleted, disabled, CLI-passthrough, workspace-scoped, or non-inference explicit profile returns gRPC `FailedPrecondition`. The host does not switch to the default after an invalid explicit value. A revised SDK calls a separate wire method for the override, so an older host returns `Unimplemented` instead of silently ignoring the selection. Existing prompt-only wire callers continue to use the platform default on a revised host. The plugin needs no provider API key because it delegates to a kandev-configured profile. This is the LLM step behind, for example, a "summarize yesterday" plugin: read the conversation with `host.Messages()`, then summarize it with `host.InvokeUtilityAgent(ctx, prompt, options...)`. **Capability gating.** Every Host RPC except `GetConfig` and `EmitEvent` is checked against your manifest's `capabilities` before the handler runs: `GetState`/`SetState`/`DeleteState`/`ListState` require `capabilities.state: true`; `GetSecret`/`SetSecret`/`DeleteSecret`/ `RevealSecret` require `capabilities.secrets: true`; `InvokeUtilityAgent` requires `capabilities.agent_invoke: true`; managed conversation operations require `capabilities.agent_conversation: true`; each data-reader accessor requires its resource in `capabilities.api_read` (e.g. `tasks`, `sessions`, `messages`, `interactions`, `workspaces`, `workflows`, `agent_profiles`, `repositories`). Calling one without the declared capability returns gRPC `PermissionDenied` with a message naming the missing capability; declare what you use. ### Live Host writes `api_write` is live, not advisory. Declare only the exact resource you mutate: `api_write: ["tasks"]` enables `host.Tasks().Create(ctx, CreateTaskInput{...})`, `.Update(ctx, UpdateTaskInput{...})`, and `.Move(ctx, MoveTaskInput{...})`; `api_write: ["messages"]` enables `host.Messages().Send(ctx, taskID, sessionID, text)`; `api_write: ["interactions"]` enables the interaction response methods above. A blank `sessionID` targets the task's primary session. Send queues behind a running session or resumes/starts it when appropriate, returning `queued`, `sent`, or `started`. Task writes use Kandev's first-party service layer, so normal task events and browser updates occur. Kandev stamps the source as `plugin:` and reserves the `metadata.source` key; plugin metadata is stored under that source. `.Update` writes title, description, state, and priority: it rejects a workflow step change. Priority accepts only `critical`, `high`, `medium`, or `low`; omitted priority on `.Create` defaults to `medium`. The read-side `Task.Labels` field remains available only as deprecated API v1 compatibility for plugins built against Kandev v0.93.0. New plugins should keep provider-specific labels or tracker annotations in plugin-owned task state and render them through task UI slots. `.Create` and `.Update` do not write Kandev task labels. Moving a task between workflow steps goes through `.Move` instead, which routes through the same path the board's own drag-and-drop move uses (validation, WIP admission, `task.moved` publication, auto-start gates, queue reconciliation), so a plugin-driven move triggers `on_enter`/`on_exit` step actions the same way a manual move does. Creating a task can select an existing repository or provide a complete, credential-free remote descriptor only when the plugin owns that `repository_providers` id. Treat all write calls as user-visible mutations and honor `ctx.Done()`. ## Authenticated declared actions Use a manifest `actions` entry for a browser action that needs the current Kandev identity and a Kandev resource, not a public webhook. The bundle calls `host.api.invokeAction`; Kandev authenticates the request, authorizes the declared `scope`, strips selectors from the untrusted body, and calls the plugin's optional `ActionHandler` with a `VerifiedActionContext`. ```yaml min_kandev_version: "0.91.1" actions: - key: "pullrequests.link" scope: "task" access: "authenticated" max_body_bytes: 32768 ``` `access` defaults to `authenticated`. Set it to `admin` for instance-wide configuration or credentials that only a Kandev administrator may manage. The host checks this policy before reading the bounded envelope or invoking the plugin, so the plugin does not need to infer roles from actor IDs. An `admin` action requires `min_kandev_version: "0.91.1"` or later; validation rejects a missing or older minimum because earlier hosts do not enforce action access. ```ts const result = await host.api.invokeAction( "pullrequests.link", { taskId, body: { pullRequestId }, }, { signal: controller.signal }, ); ``` The JSON envelope uses camelCase resource selectors: `{ workspaceId?, taskId?, sessionId?, repositoryId?, body? }`. It is not a source of authority. A `workspace` action requires only `workspaceId`; a `task` action requires `taskId` (an optional matching `workspaceId` is checked) and may include `repositoryId` only when that persisted repository is attached to the task. It may include `sessionId` only when that session belongs to the task. When both are present, Kandev verifies the repository worktree and derives its non-empty head branch; a `repository` action requires `workspaceId` and `repositoryId`. The plugin gets only host-verified `actorID`, `workspaceID`, `taskID`, `sessionID`, `repositoryID`, and derived `headBranch` plus the bounded JSON `Body`. Unknown actions return 404; bad envelopes and scope-selector combinations return 400; unauthenticated calls return 401; and members calling an `admin` action receive 403. The host gives each action 15 seconds and cancels its RPC when the browser abandons the request. Pass the `AbortSignal` supplied to your UI calls, and in the backend check `ctx.Done()` before and during provider I/O. An action reply is capped at 1 MiB. A zero response status means 200; explicit statuses from 200 through 599 let the plugin report safe domain failures such as 400, 409, or 429. The response may set only `Content-Type`, `Cache-Control`, `ETag`, or `Retry-After`; the host rejects invalid statuses, redirects, cookies, arbitrary headers, and unexpected internal error text. Use `pluginsdk.CategorizeActionError` or `pluginsdk.CategorizeActionErrorWithRetry` inside the backend instead of classifying `err.Error()` text. The stable categories are `invalid_argument`, `unauthenticated`, `permission_denied`, `not_found`, `conflict`, `rate_limited`, `unavailable`, and `upstream`; `pluginsdk.ActionErrorHTTPStatus` projects their shared HTTP status. Preserve wrapped causes for `errors.Is`/`errors.As`, but return a sanitized response message. A retry hint belongs in the typed error and the allowed `Retry-After` header, never in string parsing. ## Provider, task, review, and reference registrations A native bundle can register a manifest-owned repository provider with `registry.registerRepositoryProvider(...)`, children of the task menu's **Link** submenu with `registerTaskAction(...)`, and review data/panels with `registerReviewProvider(...)`. These registrations are revoked automatically when the plugin disables or uninstalls. Repository and review providers are exclusive by provider id; declare the id in `repository_providers` before registering it. Provider IDs must already be canonical lowercase identifiers; the manifest and runtime registry reject case variants instead of treating them as separate owners. Provider callbacks receive an `AbortSignal` and must cancel fetches rather than publishing results after their host surface has gone away. Kandev overwrites `RepositoryInspection.providerId` with the owning registration ID for both listing and URL inspection, so result data cannot claim another provider's namespace. `matchesURL` is an optional, synchronous performance hint, never an ownership decision. Omit it when ownership depends on workspace configuration (especially self-hosted origins). Kandev asks every remaining candidate to run cancellable, workspace-scoped `inspectURL`; return `null` for a URL the configured provider does not own. Exactly one structured inspection may succeed. Multiple successes are rejected as ambiguous instead of selecting registration order, while a real inspection failure is surfaced when no provider establishes ownership. ### First-use repository task creation The browser `inspectURL` callback supports the repository picker. Its result is display data and is not trusted for a native task write. To support a native task that uses a repository not yet saved in the workspace, declare this action: ```yaml actions: - key: "repositories.inspect" scope: "workspace" max_body_bytes: 16384 ``` Kandev invokes the active manifest owner from the backend. It supplies a verified workspace context and a body with only the submitted URL: ```json { "url": "https://code.example.com/owner/repository" } ``` The preferred response nests the complete descriptor under `repository`: ```json { "repository": { "provider_id": "acme", "provider_host": "https://code.example.com", "provider_scope": "workspace-a", "provider_repository_id": "owner/repository", "owner_or_project": "owner", "name": "repository", "clone_url": "https://code.example.com/owner/repository.git", "default_branch": "main" } } ``` The host also accepts the descriptor fields at the top level for compatibility. Return `{"matched":false}` when the provider does not own the URL. The host requires a matching `provider_id`, a valid HTTPS provider origin, a scope of at most 512 bytes, and complete repository identity fields. The clone URL must be HTTPS, contain no credentials, and use the same origin as `provider_host`. Provider and repository identity fields must not contain NUL bytes. The host also checks any provider scope or repository ID hint that came from the picker. The action has a 15-second deadline and a 1 MiB response limit. Do not return credentials or provider error details. Invalid output maps to a validation error, `{"matched":false}` maps to not found, and provider or transport failures map to an unavailable error. After successful inspection, Kandev persists the validated descriptor with the normal native task flow. Existing repository IDs and built-in provider URLs continue to use their existing paths. A code-host review provider may publish normalized task chrome on each snapshot: ```ts interface ReviewItemSummary { providerId: string; reviewKey: string; title: string; url: string; connectionScope: string; repositoryId: string; changeRequestNumber: string | number; state: string; taskStatus?: { number: number | string; state: "open" | "merged" | "closed" | "draft"; pipelineState: "success" | "failure" | "pending" | "neutral"; checks: readonly { id: string; label: string; state: "success" | "failure" | "pending" | "neutral"; detail?: string; url?: string; }[]; review?: { state: "approved" | "changes_requested" | "pending"; approved: number; required?: number; requested?: number; }; unresolvedComments?: number; loading?: boolean; error?: string; updatedAt?: number; }; } ``` Kandev automatically renders `taskStatus` in the same task-topbar button, composer CI chip, desktop hover popover, and mobile drawer used by first-party code hosts. A rendered linked-task row acquires a deduplicated initial provider refresh, so its semantic icon color updates before hover; hover/focus can refresh again. Active topbar/composer status refreshes every 90 seconds. Do not register `chat-top-bar`/composer lookalikes or run another status poller in the plugin. If persisted repositories from your provider should populate Kandev's native task branch picker, also declare a workspace-scoped `repositories.branches` action. Kandev calls it from the backend with `body.repository` containing the stored, credential-free snake-case descriptor (`provider_id`, `provider_host`, `provider_repository_id`, `owner_or_project`, `name`, `clone_url`, and `default_branch`). Return `{"branches":[{"name":"main","commit":"optional","is_default":true}]}`. The active manifest owner is resolved by Kandev; never use browser input to choose the repository or provider for this operation. `reference_sources` declares dynamic `#` composer sources. Implement both `SearchEntityReferences` and `AuthorizeEntityReference`: search candidates are display data only. At submission Kandev reconstructs the canonical reference, checks its workspace/provider/kind, and calls the active plugin again with the `submission` purpose. Return allow only after a current provider-side access check; timeout, error, disabled plugin, or denial fails closed. For a manifest-owned repository provider, `ResolveGitCredential` and `GetGitCredentialBinding` are optional SDK extensions used by the generic Git credential broker. Credentials are transient and must never be logged or persisted. The binding is a non-secret, opaque revision for the exact verified provider/workspace/task/session/repository/host/path scope. Change it whenever credentials rotate or disconnect; Kandev compares it around redemption and revokes provider leases when the plugin becomes inactive, so stale helpers fail closed. Kandev supplies that complete scope for initial host-side cloning too; plugins should reject missing task, session, or repository identity rather than weakening authorization to workspace-only access. The same contract is used for pre-environment origin refresh. Once it succeeds, Kandev's local and worktree preparers use refreshed refs and do not contact the remote again outside the credential seam. **External login (`capabilities.auth`).** An auth-capable plugin can log a visitor in against an external IdP (OIDC/SAML). Handle the IdP callback / SAML ACS in a `webhook`, validate the token yourself, then set the reserved `X-Kandev-Auth-Login` response header to a JSON object `{"provider","subject","email","display_name"}`. Kandev maps it to a user (link-by-email or just-in-time member provisioning), mints the session, and sets the session cookie itself (the host derives the name from the request host: `kandev_session` on default ports, `kandev_session_` otherwise, unless `auth.cookieName` is explicitly configured, in which case that name is used verbatim and must be unique per cookie host); your plugin never handles the raw token, and any `Set-Cookie` you return is dropped. Requires authentication enabled; emitting the header without `capabilities.auth` returns 403. Declare both the initiate webhook and the callback webhook with `access: public`. Kandev checks the initiate key before it shows the login button. The manifest has no callback field, so your plugin must declare the callback key separately. Kandev logs a warning when a declared initiate webhook is not public. **You MUST only assert an `email` the IdP has verified as owned by `subject`.** Kandev auto-links that email to (or provisions) an account, so an unverified or user-settable email claim is an account-takeover vector. Kandev refuses to auto-link to an admin account as defense-in-depth, but it cannot tell a verified email from an unverified one; that is on your plugin. See ADR 0050. **Writable data directory.** Kandev injects `KANDEV_PLUGIN_DATA_DIR` into every spawned plugin subprocess: a per-plugin writable directory (`~/.kandev/plugins//data`) for anything you'd rather keep on disk than in `Host` state. #### Host-state idempotency example Declare state, embed the no-op base, and read the Host at handling time because the broker connection may not exist during construction. ```yaml capabilities: events: ["task.created", "task.state_changed"] state: true ``` ```go import ( "context" "errors" ) type plugin struct{ pluginsdk.UnimplementedPlugin } func (p *plugin) OnEvent(ctx context.Context, event *pluginsdk.Event) error { if event == nil || event.EventID == "" { return errors.New("event ID is required") } host := p.Host() if host == nil { return errors.New("plugin host unavailable") } value, found, err := host.GetState(ctx, "instance", "", "events") if err != nil { return err } if !found { value = map[string]any{} } processed, _ := value["processed_event_ids"].(map[string]any) if processed == nil { processed = map[string]any{} } if _, seen := processed[event.EventID]; seen { return nil } count := 0.0 if found { count, _ = value["count"].(float64) } processed[event.EventID] = true value["processed_event_ids"] = processed value["count"] = count + 1 return host.SetState(ctx, "instance", "", "events", value) } ``` The durable EventID claims make retries no-ops. Delivery is sequential per plugin, while Host state itself has no transaction primitive; keep the claim and counter in one state update and bound or prune old claims in a long-lived plugin. ## Optional: native UI A plugin may ship `ui.bundle` in its manifest: a static browser ES module served verbatim from the extracted package directory. It may be hand-written or generated by your checked-in UI build; package the resulting bundle and never bundle a second React or Radix runtime. ![A native plugin route rendered inside kandev: a sidebar nav item the plugin registered, the host's page title bar, and page content reading live task data from the shared app store.](../screenshots/plugin-native-page.png) The single entry point: the bundle, once evaluated, calls `window.registerKandevPlugin(id, { initialize(registry, host), destroy?() })`. Kandev's frontend host imports the bundle on boot (or on runtime enable), then calls `initialize(registry, host)`. On disable/uninstall it calls `destroy?.()` and bulk-revokes every registration the plugin made. **Registry surface** (`registry: PluginRegistry`, passed to `initialize`): ```ts interface PluginRegistry { // Top-level SPA route, exact-match against window.location path. The host // wraps the page in kandev's title bar by default; configure or opt out // via options.topbar. registerRoute( path: string, Component: React.ComponentType, options?: PluginRouteOptions, ): void; // Sidebar/main nav entry, rendered by . registerNavItem(item: NavItem): void; // Route under /settings/plugins/{id}/..., rendered inside the settings shell. registerSettingsRoute(path: string, Component: React.ComponentType): void; // Native Settings > Integrations entry and global/workspace settings page. registerIntegrationSettings( registration: IntegrationSettingsRegistration, ): void; // Named slot injection. Initial slots: "task-sidebar", "settings-nav", // "main-nav-footer", "chat-input-actions", "chat-submit-decoration", // "chat-top-bar", "main-top-bar", // "app-status-bar-left", "app-status-bar-right", and "plugin-settings" // (see "Named slots" below). registerComponent( slot: string, Component: React.ComponentType<{ slotProps?: unknown }>, ): void; // WS action handler, bridged into the existing lib/ws dispatch. registerWsHandler(action: string, handler: (payload: unknown) => void): void; // Bind a handler to a keybinding declared in this plugin's manifest // (ui.keybindings[].id). See "Keybindings" below. registerKeybinding(id: string, handler: (event: KeyboardEvent) => void): void; } type PluginIcon = string | React.ComponentType<{ className?: string }>; interface NavItem { id: string; label: string; path: string; // Curated icon name or plugin-owned component; unknown names render the puzzle glyph. icon?: PluginIcon; // "main" (default): top-level sidebar entry. "integrations": renders inside // the sidebar's Integrations section alongside first-party integration links. // Both also render in the phone menu sheet, so plugin pages stay reachable // when the desktop sidebar is hidden. // "settings" is accepted by the type but not rendered by any sidebar section. // Use registerSettingsRoute for plugin administration, or // registerIntegrationSettings for service configuration in native Integrations. section?: "main" | "settings" | "integrations"; } interface IntegrationSettingsRegistration { id: string; label: string; description: string; icon?: PluginIcon; Component: React.ComponentType<{ workspaceId?: string }>; // Optional action in the detail section header and integrations index card. // The surface identifies the host location. action?: React.ComponentType; } type IntegrationSettingsActionSurface = "detail" | "index"; interface IntegrationSettingsActionProps { workspaceId?: string; surface: IntegrationSettingsActionSurface; } interface PluginRouteOptions { // Kandev-style title bar above the page. Default: enabled with a derived // title (from the matching nav item, else the plugin's display name). // Pass a PluginPageChrome to configure it, or `false` for a full-bleed // page that owns its own chrome (e.g. with host.ui.PageTopbar). topbar?: boolean | PluginPageChrome; } interface PluginPageChrome { title?: string; subtitle?: string; icon?: PluginIcon; backHref?: string; // default "/" backLabel?: string; // default "Kandev" actions?: React.ComponentType; // rendered on the right side of the topbar } ``` **Host API** (`host: PluginHostApi`, passed to `initialize`): ```ts interface PluginHostApi { pluginId: string; React: typeof import("react"); // shared host React instance; MUST use this, never bundle your own React jsx: typeof React.createElement; // convenience alias context: { getActiveWorkspaceId(): string | undefined; subscribeActiveWorkspace(listener): () => void; getWorkspaceIds(): readonly string[]; subscribeWorkspaces( listener: (workspaceIds: readonly string[]) => void, ): () => void; getTaskCreationContext(workspaceId: string): TaskCreationContext | null; subscribeTaskCreationContext(workspaceId: string, listener): () => void; resolveRepositoryId(identity: { workspaceId: string; providerId: string; providerScope: string; providerRepositoryId: string; }): string | undefined; }; api: { // fetch scoped to /api/plugins/{id}/...; relayed to your webhook handler. fetch(path: string, init?: RequestInit): Promise; // Authenticated manifest action. Selectors are verified by Kandev and // delivered separately from the untrusted body. invokeAction( key: string, input?: { workspaceId?: string; taskId?: string; sessionId?: string; repositoryId?: string; body?: unknown; }, options?: { signal?: AbortSignal }, ): Promise; // Backend API origin ("" when the SPA and API share an origin); lets a // plugin reach first-party kandev REST endpoints directly. baseUrl: string; }; ui: PluginUIApi; // named curated host components; see @kandev/plugin-sdk i18n: { readonly locale: string; t( key: string, options?: { defaultValue?: string; count?: number; values?: Record; }, ): string; useTranslation(): { readonly locale: string; t: PluginHostApi["i18n"]["t"]; }; }; theme: "light" | "dark"; // Soft SPA navigation (history push/replace), same as the app's own router. navigate(href: string, options?: { replace?: boolean }): void; // Imperatively opens a modal window. See "Modal windows" below. openModal(options: PluginModalOptions): PluginModalHandle; // Native task change-request link workflow. See "Task link dialogs" below. openTaskLinkDialog(options: PluginTaskLinkDialogOptions): PluginModalHandle; // Registers one plugin-owned contributor with the native settings save bar. // The host prefixes the id with `plugin::` before coordination. useSettingsSaveContributor(contributor: SettingsSaveContributor): void; // Publishes one integration registration's live enabled state for one // workspace. Persist the source of truth with host.storage and republish it // after load. setIntegrationEnabled( integrationId: string, workspaceId: string, enabled: boolean, ): void; } interface SettingsSaveContributor { id: string; order?: number; revision: string | number; isDirty: boolean; canSave?: boolean; invalidReason?: string; save(revision: string | number): Promise | void; discard(revision?: string | number): Promise | void; } interface PluginModalOptions { title?: string; // rendered in DialogHeader/DialogTitle; omit for no title description?: string; // supporting copy below the title content: React.ComponentType; // reuses the slot-component contract size?: "sm" | "md" | "lg" | "xl"; // default "md" dismissible?: boolean; // overlay click / Escape; default true presentation?: "dialog" | "drawer"; // default dialog } interface PluginTaskLinkDialogOptions { title: string; description: string; inputLabel: string; placeholder?: string; emptyError: string; failureMessage: string; successMessage: string; inputTestId?: string; errorTestId?: string; submitTestId?: string; onSubmit(reference: string, signal: AbortSignal): Promise; } interface PluginModalHandle { close(): void; // no-op if already closed } ``` A compatibility-only `host.store` remains for older bundles, but it is absent from `@kandev/plugin-sdk`. New plugins must not depend on private `AppState` records or mutate the SPA store. A plugin bundle must render with `host.React` / `host.jsx`; bundling your own React copy breaks hook identity against the host tree. `host.ui` is a curated `@kandev/ui` subset: Alert, Badge, Button, Card, Checkbox, Dialog, DropdownMenu, Input, Label, Pagination, ScrollArea, Select, Separator, Sheet, Skeleton, Spinner, Switch, Table, Tabs, Textarea, Tooltip (each with their compound sub-parts, e.g. `DialogContent`, `TableRow`) plus first-party app UI: `Combobox` (the app's picker), `PageTopbar` (the title bar a route gets by default via `registerRoute`'s `options.topbar`, exposed here for routes that opt out and render their own chrome), and `TaskCreateDialog`, so a plugin can hand off task creation to kandev's real create-task flow (repo/branch/agent pickers, validation) instead of POSTing directly. Code-host plugins also receive `ChangeRequestList`, `ChangeRequestRow`, `ChangeRequestDetail`, `IntegrationListToolbar`, `IntegrationScopeBar`, `IntegrationSaveQueryDialog`, `IntegrationStartTaskMenu`, `IntegrationIcon`, `TaskRowIndicator`, `IntegrationRepositoryFilter`, and `IntegrationCursorPagination`. These are the same provider-neutral dashboard components used by Kandev's GitHub and GitLab pages. Supply normalized data and callbacks instead of cloning their markup: the shared **Task** preset menu opens `TaskCreateDialog` directly, while review stays in the plugin's registered task review surface. `IntegrationIcon` accepts semantic names (`pull-request`, `pull-request-closed`, `merged`, and `filter`) so code-host plugins use the host's exact glyphs instead of copying SVG paths. Runtime components remain host-owned; do not move or duplicate them in a plugin UI package. See `apps/web/lib/plugins/host-api.ts` for the exact current list. Native integration settings also expose `IntegrationAuthStatusBanner`, `IntegrationEnabledControl`, `SettingsSection`, `SettingsCard`, and `WorkspaceScopedSection`. The host supplies the shared settings layout and save coordination; the plugin supplies provider fields and persistence. `host.utils.integrationStatusRefreshMs` is the host polling interval used by native integration health controls. Use it when a plugin must match that refresh cadence. A repository provider may implement `createChangeRequest`. Kandev keeps the native Create PR dialog and Git eligibility rules, pushes the selected checkout through the executor, and only then invokes the provider with the host-verified task and persisted repository plus the session whose checkout was pushed. The provider should forward that `sessionId` as an authenticated task-action selector; Kandev derives the exact head branch from its session worktree and the plugin uses `VerifiedActionContext.HeadBranch`. Never send or trust a browser body `source` branch. Set `supportsDraft: false` when the provider cannot create drafts. Do not add a second plugin-owned create button or send provider creation through agentctl. Return `{ url, provider?, output?, linked?, associationError? }`. When the remote change request exists but task association failed, return `linked: false` plus a safe `associationError`; Kandev warns the user to retry only the **Link** action and never offers to repeat remote creation. Respect the supplied `AbortSignal`: cancellation stops host feedback, but it cannot make an already-created remote change request safe to create again. An open registered review participates in the same native action eligibility, so the primary action stops offering Create PR once that change request is linked. A review provider can implement the workspace association snapshot/subscription/refresh trio plus `unlink`. Kandev then owns sidebar/Kanban/list PR indicators and the shared desktop/mobile unlink control. `unlink` removes only the selected task association and must not delete the remote change request. After it resolves, Kandev refreshes both the task review snapshot and the workspace association snapshot. On desktop, hovering or keyboard-focusing an association indicator refreshes the matching task review and renders the same structured pull-request summary used by first-party providers. The host also leases one initial refresh for each rendered linked task, deduplicated with any topbar or panel consumer, so status color does not depend on first opening the popover. Publish `ReviewItemSummary.taskStatus` to supply state, review, and CI rows; do not add a plugin poller. Mobile exposes the same review data through the native Status and Review surfaces because it has no hover interaction. Each `ReviewTaskAssociation` and `ReviewItemSummary` must include `connectionScope`, immutable `repositoryId`, and `changeRequestNumber`. Kandev matches them only by that complete identity, so a renamed repository remains linked while a new repository reusing the old display path cannot inherit its task or mutation authority. `reviewKey` is display and lookup data, never an authorization key. The host drops incomplete provider records instead of falling back to a mutable display key. Registered review panels use `host.ui.ChangeRequestDetail`, the same detail component consumed by GitHub. Supply provider-neutral identity, state, branches, diff totals, description, reviews, requested reviewers, checks, comments, advertised actions, and refresh/context callbacks. Kandev owns the exact header and section layout, status icons, add-to-context behavior, one scroll container, loading/error states, and native desktop/mobile presentation. Provider-specific review markup is not a supported parity path. Code-host plugins that must preserve a verified provider descriptor can pass `TaskCreateDialog` a create-mode transport override: ```ts createTask?: (payload: TaskCreatePayload) => Promise; ``` The callback receives the exact payload built by the native dialog. Route it through your authenticated plugin action and `Host Tasks.Create`. If omitted, the dialog keeps using Kandev's normal REST task endpoint. The callback is also used for the fresh-branch re-consent retry; edit and session modes ignore it. Send only the native task choices and a per-dialog idempotency identifier. Resolve the provider repository and branch again inside the authenticated plugin action; never accept a browser-supplied repository descriptor as authority. Reuse the identifier for retries of one submission, but generate a new one when the user opens a new launch so one change request can have multiple tasks. Repository identity is not a display slug. `RepositoryInspection.repositoryId` must be the provider's immutable repository identifier. Self-managed providers also set `providerScope` to an opaque, credential-free connection identity that distinguishes instances sharing one authority (for example, two Data Center context roots). Kandev persists this as `provider_scope` and keys provider rows and managed clone paths by workspace + provider + scope + immutable repository ID. `providerHost`, owner, name, and clone URL remain routing/display data; reconnecting must not silently reinterpret an older unscoped row. ### Modal windows `host.openModal(options)` imperatively opens a host-owned Dialog, rendered by a `` mounted once inside the authenticated AppShell's theme/tooltip/toast provider tree, isolated behind its own error boundary, and auto-closed if the plugin is disabled or uninstalled while it's open. It's independent of keybindings: call it from a keybinding handler, a nav route, a slot component, or a WS handler. It complements the declarative `host.ui.Dialog`; reach for `host.ui.Dialog` when a dialog is embedded in a slot's own render tree, and `host.openModal` when you need to pop one open imperatively from anywhere in your plugin's code. ```js const handle = host.openModal({ title: "Acme settings", content: SettingsPanel, size: "lg", }); // later, e.g. after the panel calls back on save: handle.close(); ``` ### Task link dialogs Code-host plugins must use `host.openTaskLinkDialog(options)` for a task menu's change-request link action. The host renders the same one-field workflow used by GitHub: title and description, inline validation, Cancel/Save footer, submitting state, success toast, and close-on-success. The plugin supplies provider copy and an authenticated submit callback. A child inside the existing **Link** submenu names only its target, such as **Bitbucket Pull Request**; do not repeat the parent verb. ```js host.openTaskLinkDialog({ title: "Link Acme pull request", description: "Use an Acme pull request URL or key for this task.", inputLabel: "Pull request", placeholder: "workspace/repository#42", emptyError: "Enter an Acme pull request URL or key.", failureMessage: "Failed to link Acme pull request.", successMessage: "Acme pull request linked", onSubmit: async (reference, signal) => { await host.api.invokeAction( "pullrequests.link", { workspaceId, taskId, body: { reference }, }, { signal }, ); }, }); ``` ## Named slots `registerComponent(slot, Component)` injects a component into a host-defined slot. The host renders every plugin's component for that slot (each isolated behind an error boundary), so a slot may hold contributions from several plugins at once. Available slots: | Slot | Where it renders | `slotProps` | | --------------------------- | ------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------- | | `task-sidebar` | Bottom of the task-detail sidebar | none | | `settings-nav` | Settings navigation tree | none | | `main-nav-footer` | Footer of the main sidebar | none | | `chat-input-actions` | Task or Quick Chat composer toolbar | `PluginComposerSlotProps` | | `task-create-input-actions` | Task creation composer toolbar | `PluginComposerSlotProps` | | `new-session-input-actions` | New-session composer toolbar | `PluginComposerSlotProps` | | `chat-submit-decoration` | Layer over the chat composer's send button, for adornments that belong on the send affordance itself | `ChatSubmitDecorationSlotProps` | | `chat-top-bar` | Session top bar on desktop; shared Plugins menu section on phones | `ChatTopBarSlotProps` | | `main-top-bar` | Default app top bar on desktop; shared Plugins menu section on phones | `MainTopBarSlotProps` | | `app-status-bar-left` | Default-left item in the global status surface | `AppStatusBarSlotProps` | | `app-status-bar-right` | Default-right item in the global status surface | `AppStatusBarSlotProps` | | `plugin-settings` | A plugin's own settings page (**Settings > Plugins > ``**), at the top above the settings form | `{ pluginId, status }` | `plugin-settings` is the one exception to "every plugin's component renders": it is **owner-scoped**, so the host renders only the component registered by the plugin whose settings page is being viewed. See "Plugin settings page" below. For a third-party service, use `registerIntegrationSettings(...)` instead of a `settings-nav` slot. Kandev adds the native integration index card, workspace settings navigation, and global/workspace routes, then wraps the plugin component in the shared settings section. IDs must be URL-safe, cannot shadow built-in integrations, and stay owned until unload. ### Workspace integration state and native save bar The optional `action` component and the main integration component both receive the `workspaceId` from the URL. The action also receives `surface`, with the value `"detail"` for the settings header or `"index"` for the integrations card. Use the workspace value for the workspace that the user is editing. Do not replace it with `host.context.getActiveWorkspaceId()`. `host.setIntegrationEnabled(integrationId, workspaceId, enabled)` updates the live **Enabled** badge for one registration. The host checks the registration owner and keeps the value in memory only. Store the durable value with `host.storage`, then publish it for every workspace after plugin load: ```js function publishEnabled(host, integrationId, enabledByWorkspace) { for (const workspaceId of host.context.getWorkspaceIds()) { host.setIntegrationEnabled( integrationId, workspaceId, enabledByWorkspace.get(workspaceId) === true, ); } } const unsubscribe = host.context.subscribeWorkspaces((workspaceIds) => { // Refresh durable values for new or removed workspace ids. }); ``` Use `host.useSettingsSaveContributor` for plugin drafts that must use the native Save changes bar. Contributor ids are local to the plugin. The host adds a `plugin::` prefix before it stores the contributor, so a plugin cannot replace a host contributor with the same local id. ### Composer actions Register `chat-input-actions`, `task-create-input-actions`, or `new-session-input-actions` to add an action to the corresponding composer. Each receives the versioned `PluginComposerSlotProps` contract described above, including presentation and native insert, focus, and submit capabilities. A task can hold several sessions, so both the active session and the full `sessionIds` list are provided. These are **kandev** session ids; resolving one to an agent/ACP transcript id (for example, to key per-session cost data from a tool like tokscale) is your plugin's job. Do that **server-side in your plugin backend** via the Host data API (`host.Sessions()` exposes each session's `ACPSessionID`), not in the bundle: propagate the ids from the UI to your backend over `host.api.fetch(...)`, and let the backend do the matching. ```js function makeChatAction(host) { const { jsx: h, ui } = host; const { Button, Tooltip, TooltipTrigger, TooltipContent } = ui; return function ChatAction({ slotProps }) { const { taskId } = slotProps ?? {}; return h( Tooltip, null, h( TooltipTrigger, { asChild: true }, h( Button, { type: "button", variant: "ghost", size: "icon", className: "h-7 w-7 cursor-pointer hover:bg-muted/40", "aria-label": "Open plugin page", onClick: () => host.navigate("/hello-world"), }, /* an icon element built with host.jsx */ myIcon(h), ), ), h(TooltipContent, null, taskId ? `Task: ${taskId}` : "Plugin action"), ); }; } // inside initialize(registry, host): registry.registerComponent("chat-input-actions", makeChatAction(host)); ``` Match the first-party toolbar buttons: `Button` from `host.ui` with `variant="ghost"`, `size="icon"`, `h-7 w-7`, `cursor-pointer`, and a 16px (`h-4 w-4`) icon. Wrap it in `host.ui.Tooltip` so it reads like the native mic/attach controls. `kandev-plugin-hello/ui/bundle.js` ships a working example. ### Session top bar Register a `chat-top-bar` component to surface at-a-glance status in the session top bar. Import its context from the public SDK: ```ts import type { ChatTopBarSlotProps } from "@kandev/plugin-sdk"; // The exported type contains: type Context = { taskId: string | null; taskTitle?: string; workspaceId: string | null; activeSessionId: string | null; // session the top bar is bound to sessionIds: string[]; // every kandev session id on the task presentation: "desktop" | "mobile"; }; ``` Like `chat-input-actions`, both the active session and the full `sessionIds` list are provided (see the note above about resolving kandev session ids to ACP transcript ids server-side). With `presentation: "desktop"`, the contribution is inline beside first-party document/editor/debug controls, so keep it to a small badge or `h-7` button that matches the native metric chips. With `presentation: "mobile"`, the contribution is in the shared menu's **Plugins** section. The host wraps multiple contributions inside the menu width and gives `host.ui.Button` controls a minimum 44px touch target. Plugin controls retain their own interaction and disclosure state; arbitrary interaction does not dismiss the menu. ```js // inside initialize(registry, host): registry.registerComponent("chat-top-bar", makeTopBarStatus(host)); ``` ### Decorating the send button `chat-input-actions` contributes a _sibling_ icon button. When the adornment belongs on the send affordance itself -- a progress ring, a state dot -- register a `chat-submit-decoration` component instead. The host layers it over the send button's own box: ```ts import type { ChatSubmitDecorationSlotProps } from "@kandev/plugin-sdk"; ``` ```ts type ChatSubmitDecorationSlotProps = { taskId: string | null; // null for task-less quick chat taskTitle?: string; activeSessionId: string | null; sessionIds: string[]; // every kandev session id on the task presentation: "desktop" | "mobile"; isSending: boolean; // the composer is dispatching this message isAgentBusy: boolean; // agent mid-turn; the next send queues disabled: boolean; // the send button is disabled planModeEnabled: boolean; // the button sends a plan request }; ``` Two rules the host enforces for you: - **The layer is `pointer-events-none`**, so a decoration can never swallow a click meant for send. For hover or focus disclosure, keep the decoration inert and observe the host send button from an effect; remove those listeners when the component unmounts. Your component renders inside the decoration layer, not beside the button, so its immediate `parentElement` is not the positioned button wrapper. Use `pointer-events-auto` only as a last resort for a separate hit target that does not obstruct send. If the plugin needs its own action, prefer a sibling `chat-input-actions` contribution. - **The layer is positioned to the button's box**, so size against `inset-0` rather than measuring the DOM. Stay inside that box: the desktop toolbar takes `overflow-x-auto` when it collapses at narrow widths, which makes CSS compute the vertical axis to `auto` as well, so anything drawn on a negative inset is clipped there. Put a ring on the button's rim, not around it. The decoration renders only while the send button does. Mid-turn with an empty composer the button is replaced by Cancel, and the decoration goes with it. Use `isSending` to stand down while the host's own spinner owns the button. ```js // inside initialize(registry, host): registry.registerComponent("chat-submit-decoration", makeCacheRing(host)); ``` ### Default app top bar Register a `main-top-bar` component to add status or a small action to the **default app top bar**, the strip across the Home, Kanban, and Tasks views, beside the CPU/DB metrics and the view/display controls. This is the app-wide, task-agnostic counterpart to `chat-top-bar`: use it for something that isn't tied to one session (a workspace-level indicator, a global quick action). The host passes: ```ts type MainTopBarSlotProps = { workspaceId: string | null; // workspace the top bar is showing, null on global home workspaceLabel?: string; // human-readable workspace name, when known currentPage: "kanban" | "tasks"; presentation: "desktop" | "mobile"; }; ``` Because the bar is not scoped to a task, no task/session ids are provided. On desktop, keep contributions to small badges or icon buttons in the compact horizontal strip. On a phone, `presentation` is `"mobile"`; the contribution renders in the shared listing menu's **Plugins** section. The host wraps contributions within the menu width and gives `host.ui.Button` controls a minimum 44px active target. Use `host.ui.Button` for documented icon actions; the host normalizes their SVG icons to 16px. Desktop contributions keep their existing sizing. ```js // inside initialize(registry, host): registry.registerComponent("main-top-bar", makeAppBarStatus(host)); ``` ### Plugin settings page Register a `plugin-settings` component to render your own UI inline on your plugin's administration page (**Settings > Plugins > ``**), at the top above the schema-driven settings form. Use it for package/runtime health or custom controls alongside that form. Service credentials, provider health, defaults, and saved watches belong in `registerIntegrationSettings(...)`. The host passes: ```ts type PluginSettingsSlotProps = { pluginId: string; // the plugin whose settings page is being viewed (always yours) status: "registered" | "active" | "error" | "disabled" | "uninstalled"; }; ``` Unlike the other slots, `plugin-settings` is **owner-scoped**: the host renders only the component registered by the plugin currently being viewed, so your card appears on your own settings page and never on another plugin's; you do **not** need to gate on `slotProps.pluginId` yourself. The host provides no wrapper card, so your component owns its own card and can render `null` when it has nothing to show. ```js // inside initialize(registry, host): registry.registerComponent("plugin-settings", makeSettingsStatus(host)); ``` ### Global Status bar Register `app-status-bar-left` or `app-status-bar-right` for app-wide, compact status UI. Kandev mounts exactly one presentation: a 24 px bar on tablet and desktop, or an in-flow Status drawer section on phone. Keep bar content small; render a touch-usable row when `presentation` is `"mobile-drawer"`. ```js function StatusContribution({ slotProps }) { const { placement, presentation, activeTaskId } = slotProps ?? {}; return host.jsx( "span", { className: presentation === "bar" ? "truncate text-xs" : "block min-h-11 px-3 py-2", }, `${placement}: ${activeTaskId ?? "no active task"}`, ); } registry.registerComponent("app-status-bar-left", StatusContribution); registry.registerComponent("app-status-bar-right", StatusContribution); ``` Each contribution receives this exact context: ```ts type AppStatusBarSlotProps = { placement: "left" | "right"; presentation: "bar" | "mobile-drawer"; density: "full" | "compact"; pathname: string; activeWorkspaceId: string | null; activeTaskId: string | null; activeSessionId: string | null; }; ``` The IDs are opaque context hints. Use a typed `host.context` read or a host-verified plugin action when the public contract exposes the needed record; request a context API extension rather than reading private store slices. Each component registration is one opaque item: Kandev does not inspect or separately reorder its children. The slot chooses the default side. A user can Cmd-drag (macOS) or Ctrl-drag (other desktop platforms) with a mouse across the full bar, and Kandev preserves that backend-owned order across reloads, restarts, and plugin disable/enable. Phone lists the saved left sequence followed by the saved right sequence and does not offer drag ordering. There is no keyboard-arrow, touch, or plugin-priority ordering API. Enable, disable, and uninstall update the live surface without a reload, and each contribution has its own error boundary. A full-bleed route (`topbar: false`) owns its own chrome; mount the host Status trigger there if that route should expose Status. ### 3. Task panel with task-scoped Host state There is now a real `registerTaskPanel` and per-user `host.storage`; prefer them over the old task-sidebar-plus-webhook workaround. ```yaml capabilities: user_state: true ``` ```js function useNoteValue(taskId, panelId) { const [value, setValue] = host.React.useState(""); const [loadedTaskId, setLoadedTaskId] = host.React.useState(null); const [readError, setReadError] = host.React.useState(false); const updatedAtRef = host.React.useRef(undefined); const dirtyRef = host.React.useRef(false); // Holds cancellation/generation state outside the effect so `refresh` is a // stable function the conflict-refetch below can also call, instead of // duplicating the read-and-commit logic without its guards. const guardRef = host.React.useRef({ cancelled: false, generation: 0 }); const refresh = host.React.useCallback( (options = {}) => { const preserveValue = options.preserveValue ?? dirtyRef.current; const guard = guardRef.current; const generation = ++guard.generation; return host.storage.get("task", taskId, "note").then( (entry) => { // Ignore a response that resolves after taskId changed, the panel // unmounted, or a newer refresh started; otherwise a stale read // (the previous task's note, or one of two overlapping reads that // resolved out of order) can land in the current field. if (guard.cancelled || generation !== guard.generation) return; if (!preserveValue && !dirtyRef.current) setValue(entry ? entry.value : ""); updatedAtRef.current = entry ? entry.updatedAt : undefined; setLoadedTaskId(taskId); setReadError(false); return true; }, () => { // Do not mark the task loaded after a rejected read. Rendering an // empty editor here would allow its first save to omit // ifUnmodifiedSince and overwrite an existing note. Keep the panel // in a retry state until an authoritative read succeeds. if (guard.cancelled || generation !== guard.generation) return false; setReadError(true); return false; }, ); }, [taskId], ); host.React.useEffect(() => { const guard = guardRef.current; guard.cancelled = false; // Clear the previous task's value/timestamp synchronously; otherwise it // stays on screen (and could be sent as ifUnmodifiedSince under the new // taskId) until this effect's first refresh() resolves. setValue(""); updatedAtRef.current = undefined; dirtyRef.current = false; setLoadedTaskId(null); setReadError(false); refresh(); // Scope echo suppression to this panel instance rather than the shared // per-tab default writer id; otherwise a second surface editing the // same note (a kanban shortcut, another panel) looks like this panel's // own echo and its write never arrives here. const unsubscribe = host.storage.subscribe( { scope: "task", scopeId: taskId, key: "note", writerId: panelId }, refresh, ); return () => { guard.cancelled = true; unsubscribe(); }; }, [taskId, panelId, refresh]); return { value, setValue, updatedAtRef, dirtyRef, loaded: loadedTaskId === taskId, readError, refresh, }; } function NotesPanel({ taskId, panelId }) { const { value, setValue, updatedAtRef, dirtyRef, loaded, readError, refresh, } = useNoteValue(taskId, panelId); const [conflict, setConflict] = host.React.useState(false); const [writeError, setWriteError] = host.React.useState(false); const pendingValueRef = host.React.useRef(undefined); const writeTimerRef = host.React.useRef(undefined); const writeInFlightRef = host.React.useRef(false); const writeBlockedRef = host.React.useRef(false); const writeGenerationRef = host.React.useRef(0); const flushWrite = host.React.useCallback(() => { if ( writeBlockedRef.current || writeInFlightRef.current || pendingValueRef.current === undefined ) { return; } const generation = writeGenerationRef.current; const next = pendingValueRef.current; pendingValueRef.current = undefined; writeInFlightRef.current = true; host.storage .set("task", taskId, "note", next, { writerId: panelId, ifUnmodifiedSince: updatedAtRef.current, }) .then((result) => { if (writeGenerationRef.current !== generation) return; updatedAtRef.current = result.updatedAt; dirtyRef.current = pendingValueRef.current !== undefined; setConflict(false); setWriteError(false); }) .catch((error) => { if (writeGenerationRef.current !== generation) return; // Stop the queue on a conflict. Refresh only the authoritative // timestamp and preserve the local value so the user can choose // whether to retry their edit; never replace dirty text silently. pendingValueRef.current = pendingValueRef.current ?? next; writeBlockedRef.current = true; if (error.name === "PluginStorageConflictError") { setConflict(true); return refresh({ preserveValue: true }); } setWriteError(true); }) .finally(() => { if (writeGenerationRef.current !== generation) return; writeInFlightRef.current = false; if (!writeBlockedRef.current && pendingValueRef.current !== undefined) { writeTimerRef.current = setTimeout(() => { if (writeGenerationRef.current !== generation) return; writeTimerRef.current = undefined; flushWrite(); }, 150); } }); }, [dirtyRef, panelId, refresh, taskId, updatedAtRef]); const scheduleWrite = host.React.useCallback(() => { if (writeBlockedRef.current || writeTimerRef.current !== undefined) return; const generation = writeGenerationRef.current; writeTimerRef.current = setTimeout(() => { if (writeGenerationRef.current !== generation) return; writeTimerRef.current = undefined; flushWrite(); }, 150); }, [flushWrite]); const retryWrite = host.React.useCallback(async () => { if (!(await refresh({ preserveValue: true }))) return; writeBlockedRef.current = false; setConflict(false); setWriteError(false); scheduleWrite(); }, [refresh, scheduleWrite]); host.React.useEffect(() => { const generation = ++writeGenerationRef.current; pendingValueRef.current = undefined; writeInFlightRef.current = false; writeBlockedRef.current = false; setConflict(false); setWriteError(false); return () => { if (writeGenerationRef.current === generation) writeGenerationRef.current += 1; pendingValueRef.current = undefined; writeInFlightRef.current = false; writeBlockedRef.current = false; if (writeTimerRef.current !== undefined) clearTimeout(writeTimerRef.current); writeTimerRef.current = undefined; }; }, [taskId, panelId]); if (readError) { return host.jsx( "button", { type: "button", onClick: refresh }, "Could not load this note. Retry", ); } if (!loaded) return host.jsx("div", null, "Loading..."); const editor = host.jsx(host.ui.RichTextEditor, { taskId, value, onChange: (next) => { setValue(next); dirtyRef.current = true; pendingValueRef.current = next; scheduleWrite(); }, }); const status = conflict ? host.jsx( "div", null, "This note changed elsewhere. Your edit is preserved.", host.jsx( "button", { type: "button", onClick: retryWrite }, "Retry my edit", ), ) : writeError ? host.jsx( "div", null, "Could not save this note.", host.jsx("button", { type: "button", onClick: retryWrite }, "Retry"), ) : null; return host.jsx("div", null, editor, status); } registry.registerTaskPanel({ id: "notes", title: "Notes", icon: "book", Component: NotesPanel, mobileEnabled: true, }); ``` On a phone, all `mobileEnabled` panels appear under one **Panels** bottom-nav action. The picker uses a touch-sized, internally scrolling sheet with each panel's icon and title; selecting a row dismisses the picker and focuses that panel as the single full-height mobile surface. The component receives `presentation: "mobile"`; desktop dockview receives `presentation: "desktop"`. The same registration and panel identity drive both viewports, so a panel remains selected through a slow or failed reload and is closed only after a ready generation omits it or the plugin is explicitly disabled/uninstalled. `writerId` is appended to the host's own per-tab id, not a full replacement; a static value like `panelId` is the same across every tab that has that panel open, so two different tabs subscribing with the same raw `panelId` would otherwise suppress each other's real, cross-tab updates as if they were local echoes. Pass `ifUnmodifiedSince` (the `updatedAt` from the last `get`) to `set` and handle the resulting `409` by refetching, rather than silently discarding a concurrent edit. `host.storage.list` returns every entry under a `(scope, scopeId)` pair with no pagination; fine for a handful of keys per task, not for an unbounded per-item collection. ### 4. Webhook receiver Declare the route, validate the method and provider signature inside the backend, and return a bounded status/body. Public webhooks are capped at 4 MiB. For plugin-UI operations, declare `access: authenticated`; those routes may raise `max_body_bytes` to 16 MiB. Kandev verifies the current user but strips its session cookie and PAT before relaying the remaining headers. On an instance with authentication enabled, a caller identified by the session cookie must additionally look same-origin, because that cookie is ambient and a page on another site could otherwise make the browser send it. The host accepts the request in exactly two cases: - it carries an accepted `Origin`; or - it carries no `Origin` and `Sec-Fetch-Site` is `same-origin` or `none`. Everything else is rejected, including `Sec-Fetch-Site` of `cross-site` or `same-site` and a request carrying neither header. Browsers omit `Origin` on same-origin `GET` and `HEAD` requests, so the second rule is what lets a panel poll its own webhook with `GET`. In practice `host.api.fetch` from an active `ui.bundle` satisfies it with no work on your part, whatever method you use. Callers identified by a PAT are not subject to this check at all, because a PAT is not ambient. That is the supported way to call an authenticated webhook from outside a browser (a script, a CLI, your own backend); a replayed session cookie carries no origin signal and is refused. ```yaml webhooks: - key: "provider-events" description: "Provider event callback" method: "POST" # informational; enforce it in HandleWebhook ``` ```go func (p *plugin) HandleWebhook(ctx context.Context, req *pluginsdk.WebhookRequest) (*pluginsdk.WebhookResponse, error) { if req.WebhookKey != "provider-events" || req.Method != http.MethodPost { return &pluginsdk.WebhookResponse{Status: http.StatusNotFound}, nil } if !validProviderSignature(req.Headers, req.Body) { return &pluginsdk.WebhookResponse{Status: http.StatusUnauthorized}, nil } // Decode, deduplicate, and enqueue the event before returning. return &pluginsdk.WebhookResponse{Status: http.StatusAccepted}, nil } ``` ### 5. Event subscriber Subscribe to exact subjects or one-segment wildcards and make processing idempotent by EventID. ```yaml capabilities: events: ["task.created", "task.state_changed"] ``` ```go func (p *plugin) OnEvent(ctx context.Context, event *pluginsdk.Event) error { // Apply the durable EventID claim pattern from the Host-state recipe before // performing side effects. if event.EventType == "task.created" { return p.handleTask(ctx, event.Payload) } return nil } ``` For critical workflows, periodically reconcile from host.Tasks() or another Host reader because event queues are bounded and delivery is best-effort. ### 6. Task contributions `registerTaskMenuAction` adds an item to native task menus. Group `"edit"` is card-only and nests inside the kanban card's `Edit` submenu. Group `"primary"` renders as a top-level item on cards and desktop/mobile task-row menus. `task-card-indicators` (see the named slots table) is the matching read-only surface, rendered beside the PR status icon on every card. `task-card-tags` is a sibling read-only surface with the same `slotProps` shape, mounted in its own row instead of that cramped title-row spot; reach for it when a contribution (for example, a row of tag chips) needs its own width. `visible(context)` and `run(context)` receive the actual `presentation`. The value is `"desktop"` or `"mobile"` for the current native task menu. `task-row-metadata` is the plugin-agnostic compact counterpart for the sidebar task tree and `/tasks` list. It receives `{ taskId, workspaceId, workflowStepId, surface: "sidebar" | "task-list" }`. Use it for read-only metadata such as labels, ownership, provider state, or tags. An empty slot adds no wrapper or spacing. ```js registry.registerTaskMenuAction({ id: "enhance-notes", label: "Enhance notes", group: "edit", visible: (context) => Boolean(context.taskId), run: async (context) => { await host.storage.set("task", context.taskId, "note", "..."); }, }); ``` With no plugin action registered, the card's `Edit` item stays flat; once any plugin registers one for group `"edit"`, it becomes `Edit > Edit task` followed by each visible action. A `run` that throws or rejects is caught and logged, not left to crash the card; the menu closes either way. Group `"primary"` actions render and behave the same way as their own top-level row, including in desktop and phone task-row menus. Do not patch first-party task components directly. An action of either group that declares `items(context)` renders as a submenu instead: `label` becomes an unselectable trigger and the returned `TaskMenuSubItemRegistration` children are its entries, in order, each called with the same `context` as the action. Nesting stops at that one level. A `primary` action's children also reach the command palette and the sidebar's task commands, one command each; `edit` stays card-only, as it always was. `items()` is synchronous and is called while the host builds that card's or row's menu entries on every render, whether or not a menu is open; a card's dropdown and context variants are built from one evaluation, so read cached state and memoize anything expensive. `run` stays required: it is the flat item a host that predates `items` renders, and the fallback whenever `items` yields nothing usable (a non-array, an empty list, a promise, or a throw, which is caught and logged). A child needs a non-blank, unique `id`, a non-blank `label` and a callable `run`, with optional fields of the shapes the entry builder understands: a boolean `disabled` (or `null`, meaning enabled) and an `icon` that is a curated name, a component, a ready-made element or `null`. A child the host cannot read or render is dropped, and one whose `id` repeats is reported and skipped. ```js registry.registerTaskMenuAction({ id: "add-tag", label: "Add tag...", group: "primary", // Optional. Turns this action into a submenu of these children. items: (context) => recentTags(context).map((tag) => ({ id: tag.id, label: tag.name, run: (ctx) => applyTag(ctx.taskId, tag.id), })), // Flat behavior, and the fallback when `items` has nothing usable. run: (context) => openTagPicker(context.taskId), }); ``` `registerTaskFilter` adds a client-side, multi-select filter section to the kanban board's display dropdown, next to the built-in Workflow and Repository sections. The plugin supplies its own options (including any "untagged"-style sentinel; the host does not special-case option values) and a `matches` predicate; filtering runs entirely against tasks already loaded in the board's in-memory state, with no backend query or persistence; selections reset on reload. ```js registry.registerTaskFilter({ id: "tags", label: "Tags", getOptions: () => [ { value: "bug", label: "Bug", color: "#ef4444" }, { value: "untagged", label: "Untagged" }, ], matches: (context, selected) => taskHasAnyTag(context.taskId, selected), }); ``` An empty selection is implicit "All" for that section: `matches` is only called once at least one option is selected, and a `matches` that throws is caught, logged, and treated as non-matching for that task. Use `registerTaskListFacet` when a plugin owns values that users should sort or group on in the `/tasks` list. Values are synchronous and apply only to the currently loaded page. A facet is removed automatically when its plugin unloads; optional subscriptions let it refresh the page. Return each value at most once for a task. Keep the same label and color for a value across all tasks. Facet sorting uses the first value label after a case-insensitive alphabetical comparison. Tasks with multiple values appear in every matching group. A task without a value is shown in the host's `Ungrouped` section. A child whose parent does not match a group is rendered at that group's root. ```js registry.registerTaskListFacet({ id: "tags", label: "Tag", getValues: ({ taskId, workspaceId }) => taskTags(taskId, workspaceId), subscribe: (listener) => tagStore.subscribe(listener), }); ``` ## Build, package, install, and test ### Plugin repository From the plugin repository created from the official template: ```bash go test ./... go vet ./... make package-host # local platform, fastest loop make package # all platforms declared by the template ``` The template's package target stages manifest.yaml, server/, ui/, and assets, then runs the monorepo plugin-pack command. If using a custom Makefile, the equivalent is: ```bash rm -rf .build/stage mkdir -p .build/stage/server cp manifest.yaml .build/stage/manifest.yaml if [ -d ui ]; then cp -R ui .build/stage/ui; fi if [ -d assets ]; then cp -R assets .build/stage/assets; fi go build -o .build/stage/server/plugin-$(go env GOOS)-$(go env GOARCH) ./server go run github.com/kandev/kandev/cmd/plugin-pack \ -dir .build/stage \ -out acme-dashboard-0.1.0.tar.gz \ -platform-only ``` plugin-pack requires manifest.yaml, rejects pre-supplied checksum files, and generates checksums.txt. It is a packager, not an exhaustive semantic or JavaScript validator: it does not execute the plugin or prove every referenced UI asset is valid. ### In-tree fixture validation The monorepo provides a maintained package smoke path without a production instance: ```bash make -C apps/backend e2e-plugin-package cd apps/backend go test ./cmd/plugin-pack ./cmd/plugin-fixture ./internal/plugins/manifest \ ./internal/plugins/pkgtar ./pkg/pluginsdk ``` The fixture build proves the current SDK/package shape and produces a host-platform archive. pkgtar.Install is the install-time authority for manifest validity, safe archive paths, checksums, managed runtime, and the host executable. It also extracts the package; it does not run the plugin or perform a full browser/module build. ### Disposable-instance smoke test Install the archive through Settings > Plugins or the local API: ```bash curl -F "package=@acme-dashboard-0.1.0.tar.gz" \ http://localhost:38429/api/plugins/install ``` Then enable it, open each registered route, exercise every declared webhook or event, verify denied capabilities fail as expected, and disable/re-enable to confirm destroy and state preservation. Uninstall only in a disposable instance; it removes the plugin package and KANDEV_PLUGIN_DATA_DIR. Reinstalling the same id/version is rejected. Bump version or uninstall before repackaging. | Layer | Command/source | Checks | Does not check | | ------- | ------------------------------------ | -------------------------------------------------------------------------------- | ------------------------------------------------------ | | Source | go test, go vet, template lint/build | Backend compilation and tests | Package paths or browser runtime | | Package | plugin-pack | Manifest presence, safe staging, generated checksums | Full manifest semantics, JS execution, live Host calls | | Install | pkgtar.Install via upload/sideload | Manifest validation, archive safety, checksums, managed runtime, host executable | Plugin behavior or UI rendering | | Runtime | Disposable instance smoke test | Subprocess, Host permissions, events, webhooks, UI cleanup | Production-scale load/provenance | ## Common mistakes - **Missing the leading slash:** ui.bundle and ui.styles must be root-relative (/ui/bundle.js, /ui/plugin.css), not ui/bundle.js. - **Forgetting capabilities:** every Host state, secret, data-reader, write, or utility-agent call fails with PermissionDenied unless its manifest capability is present. - **Confusing plugin_state with host.storage:** Host state is backend, plugin-scoped JSON with no per-user identity; host.storage is per-user. - **Reusing a raw surface id as writerId:** a static id like panelId is the same across every tab that has that surface open. Passed as-is to host.storage's writerId, it makes two different tabs look like the same writer and suppresses real cross-tab updates as if they were local echoes; the host already appends it to a per-tab id, so pass the surface id, not a fabricated combined string. - **Writing outside KANDEV_PLUGIN_DATA_DIR:** arbitrary files belong below the injected per-plugin directory; do not write beside the Kandev database or into another plugin's directory. - **Leaving stale frontend registrations:** use destroy, unsubscribe store/WS listeners, clear timers, and rely on host bulk revocation after disable or uninstall. - **Importing direct DB/internal packages:** use apps/backend/pkg/pluginsdk and typed Host methods. Direct database access is outside the plugin contract. - **Trusting webhook metadata:** `webhooks[].method` is informational. Public routes are not authenticated by Kandev, so validate method, signature, timestamp, replay protection, and body before side effects. - **Authenticated webhook access:** a valid Kandev session or PAT, plus a same-origin request for the session case, is all the host checks. Any signed-in user reaches an authenticated webhook, so enforce your own per-user or per-role rules when the endpoint needs them. It is not an authorization boundary, and it is not a CSRF boundary for your own state either: the host proves the request came from its own origin, not that the user meant to trigger whatever your handler does. - **Bundling React:** use host.React, host.jsx, and host.ui; a second React or Radix copy breaks shared contexts and portals. - **Shipping the wrong binary name:** every declared executable must be under server/, match its - key, and include .exe on Windows. Related: [Plugins](plugins.md), [Plugin manifest reference](plugins-manifest.md), [Plugin marketplace](plugins-marketplace.md), and [Extending Kandev](extending-kandev.md).