fix(plugin-detail): copy object-valued cells as JSON, not [object Object]

.changeset/8395-detail-copy-object-values.md

@@ -0,0 +1,34 @@
+---
+'@object-ui/plugin-detail': minor
+---
+
+`DetailSection`'s click-to-copy no longer writes `[object Object]` for object-valued
+cells (objectui#8395).
+
+The copy affordance built its payload with `String(value)`, and `String()` of an object
+is the literal text `[object Object]`. Because the affordance is offered for every
+non-empty value — objects included — a reader clicking the copy button, the row, or
+pressing Enter on an **address**, **geolocation**, **JSON**, **file/attachment**,
+**expanded lookup**, **repeater** or **image** cell silently got that placeholder on the
+clipboard, while the cell beside the button rendered the same value correctly. Nothing
+errored; it was noticed only on paste.
+
+Objects are now serialized with `JSON.stringify`, so those cells copy the stored value
+losslessly and parseably.
+
+**Non-objects are byte-identical.** A number still copies `16` (not the rendered
+`16.00`), a currency `1234.5` (not `1,234.50`), a percent `0.123` (not `12%`), a date
+`2026-03-04` (not `Mar 4`), and a select its stored `won` (not `Closed Won`). Copying
+the *rendered* text was measured and rejected: it is the worse contract for 9 of 17
+field types and loses data silently.
+
+**One payload moves without having been broken:** a multiselect stored as
+`['alpha','beta']` copied `alpha,beta` and now copies `["alpha","beta"]` — an array is
+an object. The new form is lossless where the old one was ambiguous for any value
+containing a comma.
+
+The JSON blob is a **defensible default, not a settled contract**. What an object cell
+*should* copy (a formatted postal address, `lat, lng`, a filename) is a per-kind product
+question tracked separately as objectui#8395's option B; the read site says so in place
+so the default is not mistaken for the answer. The `password` / `secret` branch of the
+same handler is untouched here — it is its own open card.

packages/plugin-detail/src/DetailSection.tsx

@@ -216,8 +216,62 @@ export const DetailSection: React.FC<DetailSectionProps> = ({
    */
   const serverFieldErrors = useInlineEdit()?.fieldErrors ?? null;
 
+  /**
+   * What the copy affordance WRITES (objectui#8395).
+   *
+   * `String(value)` on an object is the literal text `[object Object]`, so
+   * every object-valued cell — address, geolocation, JSON, file, expanded
+   * lookup, repeater — silently put a placeholder on the clipboard, while the
+   * cell BESIDE the button rendered that same value correctly. Objects are
+   * serialized as JSON here instead: lossless, parseable, never
+   * `[object Object]`.
+   *
+   * ## The JSON blob is a DEFENSIBLE DEFAULT, NOT A SETTLED CONTRACT
+   *
+   * What an object cell *should* put on the clipboard is a product question
+   * with several defensible answers per kind — the formatted postal address
+   * the reader can see, `lat, lng` for a geolocation, a filename for a file,
+   * the option labels or the stored values for a multiselect. That contract is
+   * objectui#8395's OPTION B (a shared value-to-text formatter that REUSES the
+   * cell renderers' own formatters — `formatAddress`, objectui#4037 — rather
+   * than re-spelling them), and it is a SEPARATE, still-unspecified card.
+   * ⛔ Do not read this line as the answer to it.
+   *
+   * ## Two shapes were measured and REJECTED — do not reach for them
+   *
+   * Copying the cell's RENDERED text is the worse contract for 9 of 17 field
+   * types and loses data silently: `date` renders `Mar 4` (the year is gone),
+   * `percent` renders `12%` against a stored `0.123` (a different quantity),
+   * `datetime` concatenates to an unparseable `3/4/20265:06 am`, and `image`
+   * and `boolean` render no text at all — so it would copy the empty string,
+   * which is strictly worse than the defect it set out to fix. And withdrawing
+   * the affordance from text-less cells would narrow `canCopy` away from
+   * `hasCellValue`, whose three readers MUST agree (see its docblock above).
+   *
+   * ## The non-regression half
+   *
+   * Non-objects keep `String(value)` BYTE-FOR-BYTE: a number still copies
+   * `16`, never the rendered `16.00`; a select still copies its stored `won`,
+   * never the rendered `Closed Won`. Pinned per kind — both halves — in
+   * `__tests__/DetailSection.copyObjectValues-8395.test.tsx`.
+   */
   const handleCopyField = React.useCallback((fieldName: string, value: any) => {
-    const textValue = value !== null && value !== undefined ? String(value) : '';
+    let textValue: string;
+    if (value === null || value === undefined) {
+      textValue = '';
+    } else if (typeof value === 'object') {
+      // The same guard `JsonCellRenderer` already applies to this exact
+      // operation on this exact value: a structure `JSON.stringify` cannot
+      // represent (a cycle) keeps today's string form rather than throwing out
+      // of a click handler, and the row stays consistent with its own cell.
+      try {
+        textValue = JSON.stringify(value);
+      } catch {
+        textValue = String(value);
+      }
+    } else {
+      textValue = String(value);
+    }
     navigator.clipboard.writeText(textValue).then(() => {
       setCopiedField(fieldName);
       setTimeout(() => setCopiedField(null), 2000);