SDK reference

Hooks

Hooks let plugins observe completed work, stop operations before they happen, or transform values as they move through Justflows. The public names and payloads are versioned in @justflows/sdk.

Actions, gates, and filters

Observe

Actions

Run after something happened. Return values are ignored. Use them for indexing, notifications, logging, and synchronization.

Decide

Gates

Run before a mutation. Call event.cancel(reason) to stop it with a message suitable for the operator.

Transform

Filters

Receive a value and must return the next value. Handlers form a predictable pipeline ordered by priority.

typescript

const unsubscribe = ctx.hooks.action(
  "content.published",
  async (event, hookContext) => {
    await updateSearchIndex(event.contentId);
  },
  { priority: 100, id: "acme.search.index" }
);

// Optional manual cleanup. The host also cleans up on deactivate.
unsubscribe();

Ordering and cleanup

Lower priorities run first; the default is 100. Handlers at the same priority keep registration order. Set once: true for one dispatch. Registration returns an unsubscribe function, and the runtime automatically removes a plugin’s handlers when it deactivates.

Hook context

The second handler argument carries correlation and identity—not secrets or server internals.

typescript

interface HookContext {
  siteId?: string;
  requestId?: string;
  source?: "http" | "job" | "cli" | "system";
  actor?: { userId?: string; role?: string };
}

Actions

Hook	Purpose	Value / payload
app.starting / app.started	Application lifecycle	{ version }
app.stopping	Application shutting down	{}
content.created / content.updated	Content row created or updated	{ contentId, siteId, type?, translationGroupId? }
content.published / content.unpublished	Publishing state changed	{ contentId, siteId, type?, translationGroupId? }
content.deleted	Content moved to trash	{ contentId, siteId, type?, translationGroupId?, lastInTranslationGroup? }
content.revisionSaved / revisionDiscarded / revisionRestored	A working revision was saved, discarded, or restored	{ contentId, siteId, revisionId, source?, actorId? }
media.uploaded	Media file stored	{ siteId, mediaId, url }
media.deleted	Media file removed	{ siteId, mediaId }
user.created / updated / deleted	User account changed	{ userId }
user.accessChanged	A user's role assignment changed	{ userId, roleId }
access.roleCreated / roleUpdated / roleDeleted	A custom role changed	{ roleId }
auth.login / auth.logout	Authentication completed	{ userId, email }
auth.loginFailed	A sign-in attempt failed	{ email, reason }
plugin.installed / activated / deactivated / uninstalled	Plugin lifecycle	{ pluginId, version, siteId? }
plugin.deleteData	Fired once a deleted plugin's deleteData() has finished	{ pluginId, version, siteId? }
theme.installed / activated	Theme lifecycle	{ themeId, version, siteId? }
core.updated	Justflows core was upgraded	{ fromVersion, toVersion, source }
webhook.delivered	An outbound webhook attempt finished	{ deliveryId, endpointId, event, attempt, status, responseStatus, responseBody, error }
request.before / request.after	HTTP request lifecycle	{ method, path, statusCode?, durationMs? }
site.underConstruction.viewed	A visitor saw the under-construction splash	{ siteId }
cache.revalidated	Selective cache revalidation completed	{ trigger, objects, siteId? }
staticExport.completed	A static / edge export run finished	{ ok, mode, outDir, publicUrl, pages, assets, bytes, pruned, durationMs, errors }
staticExport.deploy	Push the exported directory to object storage or a CDN	{ outDir, publicUrl, manifest, summary }
email.queued / sent / failed	System email delivery lifecycle	{ messageType, recipient, transport, status, attempt, detail?, templateKey?, locale? }

Gates

Hook	Purpose	Value / payload
content.beforeCreate	Validate or cancel content creation	{ input: { siteId, type?, title, slug?, excerpt?, fields? } }
content.beforeUpdate	Validate the proposed revision	{ contentId, siteId, revision?, revisionId? }
content.beforePublish	Block publishing with a human-readable reason	{ contentId, siteId, revision?, revisionId? }
content.beforeDelete	Validate deletion	{ contentId, siteId }
media.beforeUpload	Validate uploads before storage	{ siteId, filename, mimeType, sizeBytes }
media.beforeDelete	Validate media deletion	{ siteId, mediaId }
email.beforeSend	Cancel a rendered system email before it queues or sends	{ messageType, recipient, transport, templateKey?, locale? }

typescript

ctx.hooks.gate("content.beforePublish", (event) => {
  if (!event.revision?.excerpt?.trim()) {
    event.cancel("Add an excerpt before publishing.");
  }
});

Filters

Hook	Purpose	Value / payload
webhook.eventTypes	Add event names administrators may subscribe to	string[]
webhook.payload	Shape JSON-safe event data before the host signs it	unknown
content.input / content.output	Transform API content	Record<string, unknown>
content.blocks	Transform the stored block tree before rendering	block tree
content.render	Transform rendered public HTML	string
comments.render	Replace the public comment thread markup	string
content.revision	Canonical live/working snapshot behind a revision gate or filter	{ title, slug, excerpt, blocks, fields }
media.metadata	Transform stored media metadata	Record<string, unknown>
navigation.items	Add or change navigation items (runs after the host resolves a menu, visibility rules applied)	NavigationItem[]
menu.design.presets	Contribute one-click menu layout presets to the visual designer (static data, ids "<pluginId>:<slug>")	MenuDesignPreset[]
menu.visibility.evaluate	Answer an item-level custom visibility condition your plugin owns (seeded false, fail-closed)	boolean
header.templates / header.resolve / header.config	Contribute, take over, or adjust site headers	HeaderTemplate[] / HeaderConfig \| null / HeaderConfig
admin.menu	Contribute admin navigation	AdminNavItem[]
plugin.settings	Overlay values on the plugin settings screen	Record<string, unknown>
plugin.settings.write	Intercept a settings save to persist domain rows and drop keys	Record<string, unknown>
openapi.document	Extend the public OpenAPI document	OpenApiDocument
http.responseHeaders	Add response headers (must run synchronously)	Record<string, string>
html.head / analytics.head	Contribute safe head markup (sync; html.head context includes the page locale)	string
theme.css	Append plugin CSS to the theme cascade	string
comments.spamBackend	Score a comment submission with an external spam service (host thresholds still apply)	SpamCheckBackend \| null
search.backend	Take over indexing and querying for site search with a plugin-owned engine	SearchBackend \| null
seo.sitemapPaths	Add public sitemap paths	string[]
staticExport.routes	Add or remove seed paths before the export crawl	string[]
staticExport.formAction	Override the <form action> written for a dynamic endpoint	string
staticExport.assets	Add same-origin asset URLs the scanner cannot discover	string[]
site.underConstruction.render	Replace the under-construction page markup (must run synchronously)	string
email.sender / email.subject / email.html / email.text	Adjust final outgoing system-email fields	EmailSender \| string

typescript

ctx.hooks.filter(
  "content.output",
  (content) => ({ ...content, enhancedBy: ctx.pluginId }),
  { priority: 120 }
);

Publish plugin-owned hooks

A plugin may emit actions, gates, and filters under its own manifest ID—for example acme.shop.order.created. Core namespaces cannot be spoofed. Export the payload types from your own package so integrators do not have to guess their shape.