fix(showcase): the prompt-drift demo renamed a payload member and called it a domain rename

metaobjects.dev/articles/prompts-are-code.html says prompt drift "is almost
never a prompt-only event — the field got renamed IN THE DOMAIN MODEL, the
prompt was just the surface nobody checked", and then shows a payload that
was a standalone `object.value` with two bare `field.string`s and no
connection to `Subscriber` at all. The drift fixture renamed a member of THAT
value object. So the page's own demonstration proved something narrower than
the sentence above it: a prompt caught a change to the prompt.

The payload members now bind to Subscriber's fields with `extends`, which is
what "a projection of the same entities" was always supposed to mean, and the
fixture's rename moves onto the entity where the article says it happens.

The binding is not decoration — it is what makes the chain forced rather than
narrated:

  1. `Subscriber.name` is renamed. `extends: Subscriber.name` on the payload
     stops resolving and the load fails with ERR_UNRESOLVED_SUPER (measured
     against the fixture, not assumed), so the payload CANNOT be left behind.
  2. Propagating it there is therefore compulsory — and that leaves the
     mustache, still writing `{{name}}`, as the one surface nothing forced
     anyone to open.
  3. `verify --templates` is what opens it: ERR_VAR_NOT_ON_PAYLOAD: name.

It also makes the generated output argue the case by itself. `status` now
inherits the enum's values and its requiredness, so the payload VO is typed
`active | paused | cancelled` instead of `string?` in TypeScript, C#, Python
and Kotlin — a projection you can see in the emitted code rather than take on
faith. (Kotlin gains a `SubscriberBlurbPayloadStatus` enum file; the JVM run
emits Java DTOs only and has no payload VO either way.)

Two things fixed in passing:

- The drift fixture's header claimed "exactly one change" while carrying two:
  it had also dropped `column: created_at`. Restored, so the claim is true and
  a reader diffing the two directories sees only the rename.
- `python/subscriber_router.py` and `csharp/SubscriberRoutes.g.cs` were ALREADY
  stale on main — verified by stashing this work and running the check against
  a clean HEAD, which reports both. The current generators emit a sort-default
  map those files predate. `regen-showcase --check` runs in the release
  preflight rather than per-push, so it went unseen; this commit carries the
  refresh.

The website will keep publishing the old snippet until the next release: the
deploy pins to the newest npm-line tag (v1.0.0 today), not main. The article's
prose has been corrected separately in wording that is true of both.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NTcEKXTQMYt84fAjuw5A2M

Author: dmealing

examples/showcase/.metaobjects/.gen-state/.hashes.json

@@ -1,22 +1,22 @@
 {
   "AppDbContext.g.cs": "314c6078030ba151687430b37e6b6ea936238bb5df02df238e4acce2f95a430d",
   "Subscriber.g.cs": "3ca160941378fbb8b6ad6acf080ff85573f463931e21b8756873a4476e5dd163",
-  "Subscriber.py": "8afba41c6c2f73bd66caee5da827dd21ef3de81e8afc77a039fb24fd6d135ab1",
-  "SubscriberBlurbPayload.payload.cs": "5e09867b8b40f9cfb464d2082c813043cb8f1f5dada9e8a58cbbaacd8a6caf4e",
-  "SubscriberBlurbPayload.py": "73017383c2e8708209f3f6ec4f06a691a8a552f7285f1bcec208ae024a91d2a0",
+  "SubscriberBlurbPayload.payload.cs": "2a02b73a14b39d3bd39b924ef017498c6ea4320b8143e893099562868a825044",
   "SubscriberFilterAllowlist.g.cs": "7428d47f6ccb64bb315266ee0564fa3803736623a34ab491435c042848c5d472",
   "SubscriberNames.g.cs": "91f6eba78657b31fceef7021c6ca6bd799524dcb5120acbc8fcbe18786787174",
-  "SubscriberRoutes.g.cs": "d08fe489063431017ba8220df57f15a201453a182088d6f82ae73499b4d2fbac",
-  "__init__.py": "daa04cec586768866d0996c779f62073e6773fe63750ff668327991fac2fd0f5",
+  "SubscriberRoutes.g.cs": "93896ab53e74872435b2527525b82564fdafd15e8033d7823c1675d6196fee3e",
+  "generated/python/Subscriber.py": "8afba41c6c2f73bd66caee5da827dd21ef3de81e8afc77a039fb24fd6d135ab1",
+  "generated/python/SubscriberBlurbPayload.py": "92ac93b66dc2a94ae623f27d85559dfc9997b1d053fad0832bd77233c27f81f5",
+  "generated/python/__init__.py": "daa04cec586768866d0996c779f62073e6773fe63750ff668327991fac2fd0f5",
+  "generated/python/subscriber_blurb_payload.py": "158acb455397e82b05cdbf799788ff0080c3a5fef5237a67a31cfac090a78fea",
+  "generated/python/subscriber_filter_allowlist.py": "73f9fbd1f29d3a1899bdb3362254e103566ff5e534370faa9b92d18bd8861af5",
+  "generated/python/subscriber_names.py": "fedc996dcfd0344c73529e4d16d0b2cef9ccfd30cde0f4725b963123eac5ef4b",
+  "generated/python/subscriber_router.py": "14063dde33a04a0e6f07bbb00a63a2149f61616fbf0c6306c4f6c360c4bd8d11",
   "generated/ts/Subscriber.queries.ts": "843e21d8ed84ecead64870b980dfa3156dd2f360ade1f1d2693a5f04bde0fb3c",
   "generated/ts/Subscriber.routes.ts": "05d57884708ed78bdad9d69744b1685bc7a310a988aec2edd2830b53b68b3315",
   "generated/ts/Subscriber.ts": "c3c1729c5c83cb8773cae76178343932d04080aec87c3a5d27916d4b412c2d33",
-  "generated/ts/SubscriberBlurbPayload.ts": "613a80a6c0ce7e967f84f7af3c587a3c6f04434a67cea838344217ab6d132fb9",
+  "generated/ts/SubscriberBlurbPayload.ts": "3513f04b4fa8480e519d63973e3b2b0d2a88d71e64af2d8986f19f9a7ea8eb78",
   "generated/ts/index.ts": "b9f04c67786b5eec1aa493958d9843b86a58406228fcfc85634559fc4b2cbfa6",
-  "generated/ts/prompts.ts": "9cd69070c5b9c1f4b1200422858ef34488c2e8aa8ea5339714629a8de72c81cb",
-  "generated/ts/requirements/subscriberCanBePausedWithoutErasingHistory.field.enum.test.ts": "a5d2494ce5340673da43f2ee3ef13d7505ee349724e8d85f377a84eafeea50ae",
-  "subscriber_blurb_payload.py": "79fe8a6e989ee4e567d4bee122dd11fc29b38211c37c7390e65811634fd0b558",
-  "subscriber_filter_allowlist.py": "73f9fbd1f29d3a1899bdb3362254e103566ff5e534370faa9b92d18bd8861af5",
-  "subscriber_names.py": "fedc996dcfd0344c73529e4d16d0b2cef9ccfd30cde0f4725b963123eac5ef4b",
-  "subscriber_router.py": "acd0cbf39d14bd0b11e49f31375cf38446caebb3a3039d5f0b9f386638403aae"
+  "generated/ts/prompts.ts": "232380afd261d1533f5bbb0c21b31a4528f375337660b9c7ac53f80863c44a98",
+  "generated/ts/requirements/subscriberCanBePausedWithoutErasingHistory.field.enum.test.ts": "a5d2494ce5340673da43f2ee3ef13d7505ee349724e8d85f377a84eafeea50ae"
 }

examples/showcase/drift/metaobjects/meta.subscriber.yaml

@@ -1,9 +1,20 @@
 # THIS FIXTURE EXISTS TO FAIL.
 #
-# It is examples/showcase/ with exactly one change: the payload member
-# `subscriberName` is renamed to `displayName`, while the mustache still writes
-# {{subscriberName}}. `meta verify --templates` therefore reports
-# ERR_VAR_NOT_ON_PAYLOAD, and THAT OUTPUT IS PAGE CONTENT — the transcript block on
+# It is examples/showcase/ with one change, made where the article says it is made:
+# in the DOMAIN MODEL. `Subscriber.name` is renamed to `displayName`, and the blurb
+# payload — whose members bind to Subscriber's fields — follows it, because leaving
+# it behind would not compile: `extends: Subscriber.name` no longer resolves. The
+# mustache still writes {{name}}, and nothing forced anyone to look at it.
+#
+# That is the whole point, and the reason this fixture is shaped the way it is. It
+# used to rename a payload MEMBER, which made the page's claim — "the field got
+# renamed in the domain model, the prompt was just the surface nobody checked" —
+# a demo of something else. The rename now starts on the entity, propagates to the
+# payload because the binding makes it, and stops at the template because nothing
+# but `verify` was watching.
+#
+# `meta verify --templates` therefore reports ERR_VAR_NOT_ON_PAYLOAD, and THAT
+# OUTPUT IS PAGE CONTENT — the transcript block on
 # metaobjects.dev/articles/prompts-are-code.html is captured from this directory,
 # not typed by hand. If this fixture ever goes green, the page is showing a stale
 # error and the payload build fails (see scripts/site/payload.ts).
@@ -30,12 +41,12 @@ metadata:
           - source.rdb:      { table: subscribers }
           - field.long:      { name: id }
           - field.string:    { name: email, maxLength: 320, required: true }
-          - field.string:    { name: name }
+          - field.string:    { name: displayName }
           - field.enum:
               name: status
               values: [active, paused, cancelled]
               required: true
-          - field.timestamp: { name: createdAt, autoSet: onCreate }
+          - field.timestamp: { name: createdAt, column: created_at, autoSet: onCreate }
           - identity.primary: { name: primary, fields: [id], generation: increment }
     # <<<
 
@@ -59,8 +70,8 @@ metadata:
     - object.value:
         name: SubscriberBlurbPayload
         children:
-          - field.string: { name: displayName }
-          - field.string: { name: status }
+          - field.string: { name: displayName, extends: Subscriber.displayName }
+          - field.enum:   { name: status, extends: Subscriber.status }
 
     - template.prompt:
         name: subscriberBlurb

examples/showcase/drift/templates/subscriber/blurb.mustache

@@ -1 +1 @@
-Write one sentence about {{subscriberName}}, whose account is {{status}}.
+Write one sentence about {{name}}, whose account is {{status}}.

examples/showcase/generated/csharp/SubscriberBlurbPayload.payload.cs

@@ -8,6 +8,7 @@ namespace Generated;
 
 public sealed record SubscriberBlurbPayload
 {
-    public string? subscriberName { get; init; }
-    public string? status { get; init; }
+    public enum Status { active, paused, cancelled }
+    public string? name { get; init; }
+    public required Status status { get; init; }
 }

examples/showcase/generated/csharp/SubscriberRoutes.g.cs

@@ -20,6 +20,10 @@ public static class SubscriberRoutes
         "CreatedAt",
     };
 
+    private static readonly System.Collections.Generic.Dictionary<string, bool> SortDefaultDesc = new(System.StringComparer.OrdinalIgnoreCase)
+    {
+    };
+
     public static IEndpointRouteBuilder MapSubscriberRoutes(this IEndpointRouteBuilder app, string prefix = "/api")
     {
         app.MapGet(prefix + "/subscribers", async (HttpContext http, AppDbContext db) =>
@@ -38,9 +42,11 @@ public static IEndpointRouteBuilder MapSubscriberRoutes(this IEndpointRouteBuild
             {
                 var parts = sortRaw.ToString().Split(':', 2);
                 var field = parts[0];
-                var desc = parts.Length > 1 && string.Equals(parts[1], "desc", System.StringComparison.OrdinalIgnoreCase);
                 if (!SortAllowlist.TryGetValue(field, out var resolved))
                     return Results.BadRequest(new { error = "invalid_sort" });
+                var desc = parts.Length > 1
+                    ? string.Equals(parts[1], "desc", System.StringComparison.OrdinalIgnoreCase)
+                    : SortDefaultDesc.TryGetValue(resolved, out var dd) && dd;
                 q = ApplySortSubscriber(q, resolved, desc);
             }
 

examples/showcase/generated/kotlin/acme/SubscriberBlurbPayload.kt

@@ -1,11 +1,13 @@
 package acme
 
+import jakarta.validation.constraints.NotNull
 import kotlin.String
 
 /**
  * GENERATED — do not hand-edit. Regenerated from metadata.
  */
 public data class SubscriberBlurbPayload(
-  public val subscriberName: String? = null,
-  public val status: String? = null,
+  public val name: String? = null,
+  @field:NotNull
+  public val status: SubscriberBlurbPayloadStatus,
 )

examples/showcase/generated/kotlin/acme/SubscriberBlurbPayloadStatus.kt

@@ -0,0 +1,13 @@
+package acme
+
+import kotlinx.serialization.Serializable
+
+/**
+ * GENERATED — do not hand-edit. Regenerated from metadata.
+ */
+@Serializable
+public enum class SubscriberBlurbPayloadStatus {
+  active,
+  paused,
+  cancelled,
+}

examples/showcase/generated/python/SubscriberBlurbPayload.py

@@ -4,16 +4,18 @@
 
 from __future__ import annotations
 
+from typing import Literal
+
 from pydantic import BaseModel
 
 
 class SubscriberBlurbPayload(BaseModel):
-    subscriberName: str | None = None
-    status: str | None = None
+    name: str | None = None
+    status: Literal["active", "paused", "cancelled"]
 
 
 class SubscriberBlurbPayloadCreate(BaseModel):
     """GENERATED — CREATE input: auto-gen PK / @mutability readOnly omitted (writeOnce is settable here, once); @default/@autoSet optional; present values validated (FR-036)."""
 
-    subscriberName: str | None = None
-    status: str | None = None
+    name: str | None = None
+    status: Literal["active", "paused", "cancelled"]

examples/showcase/generated/python/subscriber_blurb_payload.py

@@ -4,17 +4,21 @@
 
 from __future__ import annotations
 
+from typing import Literal
+
 from pydantic import BaseModel, ConfigDict
 
+Status = Literal["active", "paused", "cancelled"]
+
 
 class subscriberBlurbPayload(BaseModel):
     """GENERATED payload for template ``subscriberBlurb``.
 
     Field shape derived from the ``SubscriberBlurbPayload`` object.value."""
 
     model_config = ConfigDict(extra="forbid")
-    subscriberName: str | None = None
-    status: str | None = None
+    name: str | None = None
+    status: Status
 
 
 __all__ = ["subscriberBlurbPayload"]

examples/showcase/generated/python/subscriber_router.py

@@ -41,6 +41,9 @@ class _SortClause(BaseModel):
 }
 
 
+_SORT_DEFAULT_ORDER: dict[str, str] = {}
+
+
 _REQUIRED_FIELDS: frozenset[str] = frozenset(
     {
         "email",
@@ -57,7 +60,11 @@ def _parse_sort(raw: str) -> _SortClause | None:
     parts = raw.split(":", 1)
     if not parts or parts[0] not in _SORT_ALLOWLIST:
         return None
-    direction = parts[1].lower() if len(parts) == 2 else "asc"
+    direction = (
+        parts[1].lower()
+        if len(parts) == 2
+        else _SORT_DEFAULT_ORDER.get(parts[0], "asc")
+    )
     if direction not in ("asc", "desc"):
         return None
     return _SortClause(field=parts[0], direction=direction)