Add the dispatch job: idempotent task generation, backfill-capable

src/functions/index.ts

@@ -1,8 +1,23 @@
 // Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
 //
-// Named callables a `script` flow node resolves by name at run time. A flow
-// function is PURE: it takes `input` and RETURNS a value; a later declarative
-// node persists it. Add yours to this map — the map itself is already wired
-// into objectstack.config.ts, so no feature branch needs to touch the config.
+// Named callables the platform resolves BY NAME at run time — a `script` flow
+// node's function, and a `defineJob`'s `handler`. Both are read from the same
+// place: `collectBundleFunctions(bundle)` over `defineStack({ functions })`.
+// Add yours to this map — the map itself is already wired into
+// objectstack.config.ts, so no feature branch needs to touch the config.
+//
+// A flow-node function is PURE: it takes `input` and RETURNS a value, and a
+// later declarative node persists it. A function that legitimately writes
+// DECLARES it (`{ handler, effect: 'writes' }`) so a run reports
+// `unmeasuredEffect` rather than claiming it wrote nothing.
+
+import { DISPATCH_HANDLER_NAME, dulyDispatch } from '../jobs/dispatch.job.js';
 
-export const dulyFunctions = {};
+export const dulyFunctions = {
+  // The dispatch job's handler. Declared `writes` because it does: it inserts
+  // `duly_task` rows directly rather than returning a value for a declarative
+  // node to persist. That is the honest declaration for a JOB handler, which
+  // has no flow graph around it to do the writing — see the note on data reach
+  // in `src/jobs/dispatch.job.ts`.
+  [DISPATCH_HANDLER_NAME]: { handler: dulyDispatch, effect: 'writes' as const },
+};