yumemi

Have a sweet Gleam. 設計を書けば、コードが生まれる。

A framework for Gleam on Cloudflare Workers. You describe an application in five words — Entity, Property, Type, Service, Authorization — and yumemi derives the Gleam implementation and every entrance to it: HTTP, MCP, CLI.

Open source, coming soon. https://gleam.canon-ical.com/

Status

Extracted from the framework/ directory of a production application on 2026-09-16, history included. Module namespace is still framework/*; the package name is yumemi. Published on Hex as yumemi (0.2.0 = the 2026-09-16 extraction; the generator and gen-3/gen-4 changes ship from 0.3.0).

Layout

gleam build

framework/server ── what the app must provide (0.11.1)

The back-end runtime (framework/server/*.mjs) is JavaScript that the generated src/gen/*.mjs imports. It knows no application names: route names, cookie names, key bindings and the party a queue consumer reads its borrowed root as come from the app’s src/server.gleam (attached_roles, browser, hooks, roots’ QueueParty). The generated face gate (<face>/src/gen/gate.mjs, declared in <face>/src/gate.gleam with framework/gate) reads the session through the ReadSession attached route. Gleam packages cannot declare npm dependencies, so the app supplies the following itself.

Generated live modules (0.11.2) send Args by their declared type: Bool as a JSON boolean (the live field’s "true" / "false"), Int / Float as numbers. On a GET route the Args that are not path holes go on the query string (an empty Option is left out), and the runtime reads bool (true / false) and float spellings from the query of GET / HEAD requests. POST / PUT / DELETE bodies are read as JSON as before.

A live field for a List(X) Arg (X a scalar, value type, id or enum) holds a JSON array of strings (["a","b"], an empty field is []); each item is sent by X’s rule. A field for a record, tuple, Dict or a List of those holds the JSON body itself (for example {"background":"#112233"}), which is sent as is and read by the back-end decoder. A field that does not parse is sent as a string, and the back end answers invalid_argument. Sum types with several constructors are sent as strings.

A Service whose logic runs step.commit and continues after it (and is not a queue consumer that only uses the commit as a boundary) ends in Accepted over HTTP: the runtime answers 202 with a one-field body ({"<root>": id}, a respond hook may rename the field). The generated live for such a Service (0.11.3) holds Reply instead of the Service’s Out: Accepted(id) for the 202 body and Replied(out) for a 200 that ends before the commit. Both arrive as Done(Ok(_)) and go on to after_send (for example ReloadPage). Lives of other Services are unchanged.

0.11.4 adds, without changing the existing public types:

• Reads time out and retry once. driver.mjs cuts a read-only statement (one SELECT / WITH / VALUES / TABLE with no write keyword — INTO and row locks count as writes — and no call to a function outside the built-in allow list, read after one pass that strips strings, quoted identifiers and comments; see framework/server/read_retry.mjs) after DATABASE_READ_TIMEOUT_MS (default 10000) and retries it once when the failure is outside the database (timeout, fetch failure, HTTP 5xx; not an SQLSTATE). Writes and transactions are never retried and get no timeout. Every failure outside the database, read or write, is logged as one JSON line ({"yumemi":"driver.failed",kind,key,attempt,ms,code,status,name,body}, kind is read / write / transaction) with the response body.
• Attached routes with a framework role that reads a body send it: the live for a SwitchSubject route has Args(kind, id) and sends {kind, id}. Other attached lives are unchanged (no Args, null body).
• The BlobCopy live copies a URL. Besides the file upload (Send), copy_from(state, url) sends {from: url} to the same route and reads {key} into Done(Ok(key)).
• Split records decode. A record Property stored with Split is rebuilt from its columns in src/gen/codec.mjs.
• Islands render sketch classes. The generated client registers each island through framework/front/island_style.mjs’s styled(app): the island gets its own sketch stylesheet while its view runs, and the CSS goes into a <style> inside the island (only when the island uses classes and does not render its own stylesheet).
• Client navigation between Pages. The generated client calls framework/front/navigate.mjs’s start({routes, boot, pageview}). A plain left click on a same-origin link, from a Page to a Page that are both in the face’s route table (minus the gate’s frame_src Pages), fetches the next page with one request (the gate, the adult declaration and the session go through the server as before), swaps <head> and <body>, re-runs the island registrations and pushes history; back / forward do the same. A redirect, a non-200, a content-security-policy header, a page with scripts other than the client, an already-registered given island, a modified click, target or download fall back to a page load.
• Pageviews count once per navigation. The navigation fetch carries x-yumemi-navigate: 1; for it the gate puts <meta name="yumemi-pageview"> in <head> instead of the pageview script (same conditions: adult session, 200 HTML, a pageview Page) and adds vary: x-yumemi-navigate. The client posts the pageview (kind spa) only after it swapped that page in; a fallback to a page load gets the script as before.
• Reload after a write stays in the page. An island’s yumemi-done calls navigate.reload(): on a routed Page it refetches the current URL the same way (no history entry, scroll kept, pageview kind reload); otherwise it reloads the page.

Imports outside the package

SQL — the runtime runs these keys through the app’s SQL bundle (src/gen/sql.mjs, built from db/queries/**). The app writes them as db/queries/framework/<name>.sql against its own framework schema (DDL is the app’s). Holes are positional, in the order below.

Worker env — DATABASE_URL, COOKIE_DOMAIN, OUTBOX (queue binding), <ENTRY>_HOST per entrance, the key_binding of browser (a Secret Store binding), the KEK bindings of Sealed properties, and optionally ISOLATE_MARKER=1 (test header).