eleven / messenger Public

web: schema apps render a virgin thread as empty, not an error (#805)

A never-used app thread has no folded state (the host only seeds on the
first event), so appStateFor hands render `undefined`. The pre-schema
hand-written To-do/Reminders renders guarded that; the schema renderer
(#478) didn't — listModel evaluated state[schema.collection] and threw,
so a fresh To-do/Reminders Interface pane showed the contained "This
view hit an error" message instead of the empty list.

Guard at the schemaRender factory seam (undefined → initialState) and
make the engine's state-taking entry points (listModel, partitionState,
tickerRules) tolerate undefined the same way, with a regression test.
Native is unaffected: SchemaAppStore seeds initialState at construction.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Paul Campbell 3 months ago 4331d9ef99329f11ea2d47d9840eaa5aeb10afb4 parent 4c785c0

4 files changed, +25 −3

changelog/2026-07-12-todo-fresh-thread-fix.md +3 −0
test/schema-engine.test.mjs +12 −0
web/static/apps/schema-engine.js +5 −2
web/static/apps/schema-render.js +5 −1

diff --git a/changelog/2026-07-12-todo-fresh-thread-fix.md b/changelog/2026-07-12-todo-fresh-thread-fix.md

new file mode 100644

index 0000000..39484a6

--- /dev/null

+++ b/changelog/2026-07-12-todo-fresh-thread-fix.md

@@ -0,0 +1,3 @@

+🤖 Fixed: opening a brand-new To-do or Reminders list on the web before adding

+anything showed "This view hit an error" instead of the empty list. Fresh lists

+now open cleanly.

diff --git a/test/schema-engine.test.mjs b/test/schema-engine.test.mjs

index 1e3d60f..360ff01 100644

--- a/test/schema-engine.test.mjs

+++ b/test/schema-engine.test.mjs

@@ -208,6 +208,18 @@ await ok("todo summary cases", () => {

assert.strictEqual(listModel(todoSchema, s, NOW).summary, "all done 🎉");

});

+await ok("undefined state reads as the empty state (virgin thread)", () => {

+ // Regression: the host only seeds state on the first fold, so a never-used

+ // app thread hands the renderer `undefined` — the engine's entry points must

+ // treat that as empty, not throw ("undefined is not an object" on the

+ // Interface view of a fresh To-do/Reminders thread).

+ for (const schema of [todoSchema, remindSchema]) {

+ assert.deepStrictEqual(listModel(schema, undefined, NOW), listModel(schema, initialState(schema), NOW));

+ assert.deepStrictEqual(partitionState(schema, undefined, NOW), { active: [], grace: [], archived: [] });

+ assert.deepStrictEqual(tickerRules(schema, undefined, NOW, new Set()), []);

+ }

+});

await ok("search filters rows across sections", () => {

let s = initialState(todoSchema);

s = foldSchemaEvent(todoSchema, s, { type: "todo.add", id: "a", text: "buy milk" });

diff --git a/web/static/apps/schema-engine.js b/web/static/apps/schema-engine.js

index f3abaa5..58c5d52 100644

--- a/web/static/apps/schema-engine.js

+++ b/web/static/apps/schema-engine.js

@@ -282,7 +282,7 @@ function applyFoldOp(schema, state, op, event) {

export function partitionState(schema, state, now) {

const p = schema.partition;

- const items = state[schema.collection] || [];

+ const items = (state || {})[schema.collection] || [];

const active = [];

const grace = [];

const archived = [];

@@ -307,6 +307,9 @@ export function partitionState(schema, state, now) {

export function listModel(schema, state, now, ui = {}) {

const view = schema.views && schema.views.main;

if (!view) return null;

+ // A never-used app thread has no folded state at all (the host only seeds on

+ // the first event), so `state` can arrive undefined — treat it as empty.

+ state = state || initialState(schema);

const items = state[schema.collection] || [];

const buckets = partitionState(schema, state, now);

const scope = { state, items, buckets, now };

@@ -503,7 +506,7 @@ export async function runAction(schema, name, scope, io) {

export function tickerRules(schema, state, now, fired) {

const t = schema.ticker;

if (!t) return [];

- const items = state[schema.collection] || [];

+ const items = (state || {})[schema.collection] || [];

const keyField = collectionDecl(schema, schema.collection).key || "id";

const out = [];

for (const rule of t.perItem || []) {

diff --git a/web/static/apps/schema-render.js b/web/static/apps/schema-render.js

index 2e6eead..ec589eb 100644

--- a/web/static/apps/schema-render.js

+++ b/web/static/apps/schema-render.js

@@ -43,7 +43,11 @@ export function schemaInitialState(schema) {

}

export function schemaRender(schema, opts = {}) {

- return (state, el, ctx) => render(schema, state, el, ctx, opts);

+ // The host passes the raw folded state, which is undefined for a thread with

+ // no events yet (state is only seeded on the first fold). The pre-schema

+ // hand-written renders guarded that themselves; guard it here for every

+ // schema app, so a virgin thread renders as the empty state, not an error.

+ return (state, el, ctx) => render(schema, state || initialState(schema), el, ctx, opts);

}

// ---- transient UI state (search query, collapsed sections) -----------------