chore(changeset): patch — per-shape surface strings + select-option editability boundary (#8202, #8201)

Reachability measured rather than inherited: both halves are parse-reachable
error strings, #8201's paragraph also reaches `dist/**/*.d.ts` hover, and the
generated reference page is measured NOT to render schema-level JSDoc.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016YBUGvukaeVu9DjKdsHJa9

Author: os-support-ai

.changeset/per-shape-guidance-completion.md

@@ -0,0 +1,70 @@
+---
+"@objectstack/spec": patch
+---
+
+docs(spec): a rejection says which shape refused the key, and a select option gets the editability boundary (#8202, #8201)
+
+Two text-face halves finishing the story PR #8199 started. No key is added
+anywhere, every spelling rejected before is rejected after, and everything that
+parsed before parses identically — only the sentence an author reads moves.
+
+## #8202 — per-shape `surface` strings
+
+`FormFieldSchema`, `FormSectionSchema` and `PageComponentSchema` shared one
+surface string, so every rejection opened `Unrecognized key(s) on this view/page
+schema`. Harmless while the three answered a key identically; since #8199 they
+do not:
+
+- on a **field**, `disabled` gets a rename pointer — *Did you mean `disabled` →
+  `readonly`?*
+- on a **section** or **page component**, it gets the editability-boundary
+  prescription — *write `readonly` on the form field(s) inside instead.*
+
+Those two answers contradict each other by design, and the contradiction only
+reads correctly if the message says which shape the author is on. It now does:
+`this form field` / `this form section` / `this page component`. Per #8199's
+placement rule the strings are filed at the three call sites rather than in the
+shared options table — a table shared by three shapes can no more carry one
+shape's name than it can carry one shape's prescription. The shared table keeps
+the family name, and no live declaration may still report it
+(`alias-integrity.test.ts`).
+
+## #8201 — `SelectOptionSchema` inherits the #7887 ruling
+
+The maintainer ruling of 2026-08-12 (a form section / page component gates
+visibility only; editability lives on fields) was scoped to two shapes, and
+#8199 left the third — a select option — with a bare rejection. It has the
+boundary now, on the ruling's own premise re-measured for this shape rather than
+by analogy: on objectui `origin/main` @ `aca27fa` the object-field pipeline these
+options feed has **zero** per-option `disabled` consumers (`SelectField.tsx:161`
+calls the root-level `disabled` "the single authority"; `RadioField.tsx:124`
+reads only `props.disabled`). The shown-but-unselectable option that does exist
+lives in objectui's SDUI vocabulary, which is not this shape.
+
+Its prescription is **not** the siblings' text, because the siblings'
+destination does not exist here — a section redirects to the fields inside, and
+an option has no inside. Writing `disabled` on an option now points at the two
+things that are real: per-option `visibleWhen` to withdraw that one option (the
+only `*When` surface that binds `current_user`, ADR-0068 — and the rule
+validator refuses a write of a value whose predicate is false), and
+`readonly` / `readonlyWhen` on the **field** to freeze the whole picker. It
+states what the platform honours today; a non-selectable field option remains a
+spec decision someone may ask for, not a key an author writes.
+
+## Why `patch`, measured rather than inherited
+
+The criterion is whether the prose reaches a consumer:
+
+- **Parse-reachable error string — YES.** Both halves are `unrecognized_keys`
+  message text an author reads out of a failed parse, and every claim is pinned
+  against a real `safeParse` error rather than against the options table.
+- **`dist/**/*.d.ts` hover — YES for #8201.** The boundary paragraph is JSDoc on
+  the exported `SelectOptionSchema` const.
+- **Generated reference page — NO, measured.** `content/docs/references/data/`
+  `field.mdx` is built from the file-level doc block plus per-property
+  `.describe()` text; a schema's own JSDoc is not rendered (grepping the page
+  for `SelectOptionSchema`'s existing docblock text returns nothing, while its
+  per-key `.describe()` string hits). No `.describe()` was touched, so the page
+  and `authorable-surface.base.json` do not move.
+
+One reachable consumer is enough and no public export is added, so `patch`.