writeonce/docs/stories/language-runtime-database/refine/37-wo-html-components.md

iteration	status
37	refine

Iteration 37 — wo-html components: an MVC-shaped view layer (Angular's format, studied)

Format: product/story-iteration-template. Part of Story — one language, one runtime, one database, one binary.

Inserted 2026-08-23 (developer ask: "enhance wo-html like MVC; understand Angular format"). Grows the wo-html LIBRARY, never the framework — the 2026-08-20 micro-framework directive stands: routing/ middleware/Req/Resp stay MVC-free, and the view layer lives in its own dependency (the site sample's two-dep lesson). Unscheduled — independent of the concurrency chain; needs its spec brainstormed first.

REDIRECTED 2026-08-23 (developer review of the shop template against a Vue SFC): render()-as-string-concatenation failed the DX referendum — markup must be markup-FIRST. New direction: view.html template files COMPILED BY woc into render code — {{ self.name }} interpolation (auto-escaped; a raw opt-out spelling for prebuilt fragments), w:if/w:for structural attributes, typed against the view class's fields at compile time (a typo'd field is a compile error), NO template engine at runtime — the doctrine's real meaning becomes "no template interpreted at request time", not "no template files". A runtime mustache-lite was considered and REJECTED: reflection-free means values degrade to map<Text, Text> — typing lost. Client-side reactivity from the Vue sample (ref, @click, v-model) stays out under the no-JS posture; qty steppers are form fields, actions are POSTs. This makes 37 a COMPILER iteration too (template-to-code lowering), gated behind the standing "no compiler/VM/database changes yet" directive — schedule accordingly. The shop template (docs/examples/shop) is the consumer: its view.wo classes become view.html + view classes, and its README's recorded gaps ride along (gap #1: pub + @table cannot combine — blocks a shared model module; gap #2: @view projection classes).

Why this iteration exists

wo-html today is element builders + one utility sheet: pages are functions concatenating Text. That works (the site proves it) but has no unit of reuse bigger than a function — no way to say "this fragment owns its data, its markup, and its place in a layout" and hand it around. Angular's component FORMAT — a class declaring its inputs, a template rendering them, composition by nesting, structural directives for repetition and choice — is the studied precedent: the FORMAT translates to server-rendered .wo; the client-side half (change detection, event bindings, SPA router) deliberately does not.

What Angular's format maps to (the study, summarized)

Angular	wo-html translation	doctrine fit
@Component class with @Input()s	a class whose FIELDS are the inputs, satisfying a structural Component interface (fn render() -> Text)	behavior-as-class; no closures needed
template ({{ expr }})	the render method's interpolation — .wo already has ${...} in Text	no template dialect: templates ARE code
*ngFor / *ngIf	explicit for/if in render() building Text — the language's own control flow	no structural-directive mini-language
content projection (<ng-content>)	a layout component taking pre-rendered Text slots as fields	slots are ordinary values
services/DI	no translation — a component reads its fields; queries stay in handlers (M and V stay separate)	rejected: DI needs function values
event bindings (click) / two-way [(ngModel)]	no translation — server-rendered, no JS doctrine; forms stay form_post round trips	rejected surface

Goals

• A Component interface in wo-html: structural (fn render() -> Text), so any class with fields + render satisfies it — the view twin of the framework's Handler. Composition is nesting: a parent's render calls children's render.
• The MVC seam stated: Model = @table rows queried in the HANDLER, moved into component fields; View = components rendering Text; Controller = the framework handler wiring them. The library documents the seam; it never queries.
• Layout components with slots: the site's nav/shell/footer become the proof — a Layout { title, nav, content, footer } component replacing today's shell() functions, chapter pages and homepage composing it.
• The site sample migrates as acceptance: same rendered bytes (or deliberately better), gate stays green — the library grew a floor, not a rewrite.

Acceptance Criteria (draft — the spec refines)

• Given a class with fields and fn render() -> Text, when a handler moves data in and calls render, then the page it serves is byte-deterministic from the fields — no hidden state, no globals.
• Given nested components (layout → section → card), when the outer render runs, then children render through the same structural interface, and escaping stays the caller-explicit esc() rule at every level.
• Given the migrated site sample, when just site runs, then 11/0 — the gate is the proof the component layer reproduces the existing pages.
• Given a component reused across two pages (the chapters card on home and chapter pages), when either page changes its data, then the other's markup is untouched — reuse is real, not copied.

Out Of Scope

• Client-side anything: change detection, event/two-way bindings, SPA routing, hydration — the no-JS posture stands; interactivity is form round trips until a directive says otherwise.
• A RUNTIME template engine (files parsed per request, mustache-style) — rejected 2026-08-23: reflection-free means untyped map<Text, Text> values. Templates compile to code at build time or they don't exist.
• Dependency injection / services — components are data-in, Text-out.
• Moving wo-html into the framework — settled 2026-08-23: separate libraries, composed via [deps].
• CSS componentization (scoped styles) — the utility sheet stays one static string; measure pain first.

Info

Forks the spec must settle (REVISED 2026-08-23 for the compiled-template direction):

1. Template pairing — Vue-SFC style (one view.html whose frontmatter/<script> block declares the fields) vs paired files (view.html + a .wo view class it compiles against). Leaning: paired — the class stays ordinary .wo, the template is pure markup.
2. Directive surface — the minimal set: {{ expr }} (auto-escaped), a raw spelling for prebuilt fragments (slots), w:if, w:for, w:class-style conditional classes. Anything beyond is YAGNI until a sample demands it.
3. Escaping default — {{ }} escapes ALWAYS (safer than today's caller-explicit esc()); the raw spelling is the only door, and it is greppable.
4. The framework seam — does ok_html(body) move into the framework beside ok_text/ok_json (transport, not rendering — flagged 2026-08-23), and does wo-html gain respond(c: Component) sugar?
5. Migration depth — shop first (the template is its acceptance), site second; web-app stays HTML-less as the counter-example.

Study sources: Angular's component/@Input/ng-content docs (format only; no Angular code enters the repo — candidate .dev/reference addition if deeper study is wanted), Go's html/template as the server-side contrast, and the site sample as the living consumer.

Proposed Solution

Brainstorm → spec → plan (the superpowers path): settle the four forks, grow wo-html by the Component interface + a Layout proof, migrate the site sample as acceptance, keep the framework untouched. Ships independently of the concurrency chain; slots wherever the developer schedules it.