fix(render): honor every ActionBinding field, per-item visible, real element lifecycle and state paths

[blove]

Six defects in @threadplane/render that yesterday's audit had to write into the docs as caveats. Each one has a vitest spec that fails before the change and passes after.

What changed

(a) signalStateStore silently dropped the first path segment. parsePointer filtered out segment 0 unconditionally, so set('count', 1) parsed to the root pointer and replaced the entire state model with 1. A path is now ''/'/' (root) or must start with /; anything else throws an Error naming the path and the required leading slash, in production as well as development — silent data loss is worse than a throw. A rejected update() applies none of its entries.

(b) Element-scope lifecycle events fired for almost nothing. <render-element> gated its mounted/destroyed emits on a truthy lifecycle field that UIElement does not declare, so in practice only the two spec-scope events ever fired and mountCount/lastMountAt on RenderLifecycleService never moved past the spec mount. The gate is gone: every element the renderer mounts emits both events with its elementKey and elementType.

(c) stateChange could not name the path that changed. StateStore.subscribe carries no path, so the event hardcoded path: '/' with the full snapshot as value. signalStateStore() now records its last mutation, exposed as lastChange() on a new exported SignalStateStore extends StateStore interface, and RenderSpecComponent reads it when present. A store from another implementation has no lastChange and keeps the '/' plus snapshot fallback.

(d) Four ActionBinding fields were accepted and never read. confirm, onSuccess, onError and preventDefault are all implemented, mirroring executeAction in @json-render/core:

• preventDefault calls preventDefault() on the emitted payload when it is a DOM Event (or carries one under event).
• confirm asks window.confirm(message) through the injected DOCUMENT's default view; a falsy answer skips the handler and both follow-ups. Without a default view there is nobody to ask and the handler proceeds.
• onSuccess (set / action / navigate) and onError (set / action) dispatch after the handler's returned promise settles, or synchronously for a non-promise result or throw. '$error.message' in an onError set map is replaced by the thrown error's message. With no onError, an error propagates as before.

(e) Action params were spread unresolved. A $state expression inside params reached the handler as a literal { $state: '/selected' }. They now go through resolveElementProps with the element's repeat scope, exactly as element props do; the emit payload still wins on key collisions.

(f) visible was not evaluated on the repeat branch. A repeating element mounted every item regardless of its condition. It is now evaluated once per item in that item's scope, so { $item: 'done', eq: false } and $index conditions hide individual rows.

Specs added

• libs/render/src/lib/signal-state-store.spec.ts — path validation on get/set/update, the root forms, and lastChange() (set, update, read from a subscriber, no-op writes).
• libs/render/src/lib/render-events.spec.ts — three-element mount emits one spec-scope plus three element-scope mounted events, an element leaving the tree emits destroyed, mountCount reaches 4, and stateChange reports the real path for a signalStateStore while falling back to '/' for a foreign store.
• libs/render/src/lib/action-bindings.spec.ts — resolved params, confirm accepted/declined, preventDefault on and off, onSuccess set/action/navigate (sync and async), onError set/action (sync throw and async rejection), and four repeat-visibility cases.

24 of these failed before the implementation and all pass after.

Docs

The pages the audit made describe the defects now describe the shipped behavior, with the warning callouts removed: render/api/signal-state-store.mdx (throw instead of silent drop, lastChange(), SignalStateStore return type), render/guides/events.mdx (full action-binding table plus sections on resolved params, confirmation, follow-ups and preventDefault; stateChange path; element-scope lifecycle), render/guides/lifecycle.mdx (mountCount counts element mounts), render/guides/repeat-loops.mdx and render/getting-started/introduction.mdx (per-item visible). api-docs.json regenerated for render and chat — chat's liveStore type moved to SignalStateStore.

Verification

• npx nx run-many -t lint,test,build --projects=render — green, 136 tests.
• npx nx run-many -t lint,test,build --projects=chat — green.
• npx vitest run --root apps/website — 1326 tests, 131 files, all passing.
• GROWTH_FORM_POLICY=growth_v1 npx nx build website — succeeds.
• Built all seven render example apps; nx e2e green for cockpit-render-repeat-loops-angular, cockpit-render-state-management-angular, cockpit-render-element-rendering-angular, cockpit-render-registry-angular, cockpit-render-spec-rendering-angular, cockpit-render-computed-functions-angular, cockpit-ag-ui-json-render-angular, plus cockpit-chat-generative-ui-angular and cockpit-langgraph-durable-execution-angular as store consumers.

There is no CHANGELOG.md under libs/render, so no changelog entry was added. No cockpit-render-events-angular project exists.

🤖 Generated with Claude Code

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1 Skipped Deployment

Project	Deployment	Actions	Updated
threadplane	Ignored	Preview	Sep 8, 2026 3:18am UTC

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