diff --git a/.changeset/sdui-parser-inline-whitespace-5661.md b/.changeset/sdui-parser-inline-whitespace-5661.md
new file mode 100644
index 0000000000..7affbea3dc
--- /dev/null
+++ b/.changeset/sdui-parser-inline-whitespace-5661.md
@@ -0,0 +1,26 @@
+---
+'@object-ui/sdui-parser': patch
+---
+
+`kind:'html'` page sources keep the space between a text run and an adjacent
+inline element: `A <strong>x</strong> page` now compiles to `A `/`<strong>`/`
+page` and renders as `A x page` rather than `Axpage` (objectui#5661).
+
+The parser collapsed each text run's whitespace to a single space — correct, and
+what HTML itself does — and then `.trim()`ed it, which is not: HTML collapses a
+whitespace run to one space, it does not delete it. The deleted space was
+precisely the separator between a run and its inline sibling, so every authored
+sentence carrying emphasis or a link in the tier the guide recommends by default
+rendered with its words run together. It was silent: the page rendered, the
+structure was right, no diagnostic fired.
+
+The rule is deliberately mechanical rather than a block/inline taxonomy invented
+for a schema tree that has none: keep one leading space when a sibling precedes
+the run, and one trailing space when a sibling element follows it. The parent's
+own start and end still drop their edge space, so `<p>  hi  </p>` is unchanged.
+
+Its one bounded cost: a whitespace-only run BETWEEN two siblings survives as a
+single space, so a pretty-printed `<ul>` gains one `' '` string child per gap
+between its `<li>`s — one space per gap, never the source's newline and
+indentation, never at the container's own edges, and never inside an item's own
+text. That bound is pinned by a test rather than left as a claim.
diff --git a/packages/sdui-parser/src/__tests__/inline-whitespace.test.tsx b/packages/sdui-parser/src/__tests__/inline-whitespace.test.tsx
new file mode 100644
index 0000000000..4724ab1729
--- /dev/null
+++ b/packages/sdui-parser/src/__tests__/inline-whitespace.test.tsx
@@ -0,0 +1,189 @@
+/**
+ * objectui#5661 — the space between a text run and an adjacent inline element.
+ *
+ * ## The defect
+ *
+ * `parseChildren` collapsed each text run's whitespace to a single space (right
+ * — that is HTML's own whitespace model) and then `.trim()`ed it (wrong — HTML
+ * collapses a whitespace run to ONE space, it does not delete it). The deleted
+ * space is exactly the one separating a run from an adjacent inline sibling, so
+ * the tier the guide recommends by default rendered every emphasised sentence
+ * with its words run together, silently:
+ *
+ *     A <strong>kind:'html'</strong> page   ->   "A" "page"   ->   Akind:'html'page
+ *
+ * ## The rule pinned here (triage decision, option (b))
+ *
+ * Collapse the run, then keep ONE leading space only when a sibling precedes
+ * the run, and ONE trailing space only when a sibling ELEMENT follows it. At
+ * the parent's own start/end the edge space is still dropped. Deliberately
+ * mechanical: it invents no block/inline taxonomy for a schema tree that has
+ * none (that was the rejected option (a)).
+ *
+ * Its known cost is bounded and pinned below: a whitespace-only run BETWEEN two
+ * siblings survives as a single space, so a pretty-printed `<ul>` gains one
+ * `' '` string child per inter-item gap. The `<ul>` control asserts the bound —
+ * exactly one space per gap, never the source's newline+indent, never at the
+ * container's own edges, and never inside an `<li>`'s own text.
+ *
+ * The last case renders through the REAL `SchemaRenderer` and reads
+ * `textContent`, because that is the term the bug was reported in: a
+ * parse-tree assertion alone cannot say the words stopped running together on
+ * screen.
+ */
+
+import { beforeAll, describe, expect, it } from 'vitest';
+import React from 'react';
+import { renderToStaticMarkup } from 'react-dom/server';
+import { ComponentRegistry } from '@object-ui/core';
+import { SchemaRenderer } from '@object-ui/react';
+import { parseJsx } from '../parse.js';
+import type { SchemaElement, SchemaNode } from '../types.js';
+
+/** The parsed children of a single-root source. */
+function childrenOf(source: string): SchemaNode[] {
+  const { tree, diagnostics } = parseJsx(source);
+  expect(diagnostics.filter((d) => d.severity === 'error')).toEqual([]);
+  return (tree as SchemaElement).children ?? [];
+}
+
+/** Concatenated text of a subtree — the parse-tree stand-in for `textContent`. */
+function flatten(node: SchemaNode | undefined): string {
+  if (typeof node === 'string') return node;
+  return (node?.children ?? []).map(flatten).join('');
+}
+
+describe('#5661: a text run keeps the space that separates it from a sibling element', () => {
+  it("case 1 — 'A <strong>…</strong> page' keeps both spaces around the element", () => {
+    const kids = childrenOf(
+      `<p>A <strong>kind:'html'</strong> page — native HTML tags and the blocks' structured props.</p>`,
+    );
+    expect(kids).toEqual([
+      'A ',
+      expect.any(Object),
+      " page — native HTML tags and the blocks' structured props.",
+    ]);
+    expect(flatten({ type: 'p', children: kids })).toBe(
+      "A kind:'html' page — native HTML tags and the blocks' structured props.",
+    );
+  });
+
+  it("case 2 — 'in the <em>html</em> tier.' keeps both spaces around the element", () => {
+    const kids = childrenOf(`<li>Full HTML tag set in the <em>html</em> tier.</li>`);
+    expect(kids).toEqual(['Full HTML tag set in the ', expect.any(Object), ' tier.']);
+    expect(flatten({ type: 'li', children: kids })).toBe('Full HTML tag set in the html tier.');
+  });
+
+  it("case 3 — 'A trusted <a>…</a> behind a flag.' keeps both spaces around the element", () => {
+    const kids = childrenOf(
+      `<li>A trusted <a href="https://objectui.org">react tier</a> behind a flag.</li>`,
+    );
+    expect(kids).toEqual(['A trusted ', expect.any(Object), ' behind a flag.']);
+    expect(flatten({ type: 'li', children: kids })).toBe('A trusted react tier behind a flag.');
+  });
+
+  it('collapses the run to ONE space — it never widens the gap', () => {
+    // Multi-space and newline runs on BOTH sides of the element, and inside the
+    // run itself. Every one of them must arrive as a single space.
+    const kids = childrenOf('<p>A\n\n   long    run   <em>x</em>\n   tail</p>');
+    expect(kids).toEqual(['A long run ', expect.any(Object), ' tail']);
+  });
+
+  it('still drops the edge space at the parent’s own start and end', () => {
+    // The half of `.trim()` that was correct. Nothing here is adjacent to a
+    // sibling, so nothing is kept.
+    expect(childrenOf('<p>   Hello   </p>')).toEqual(['Hello']);
+    // A pretty-printed element child: the whitespace-only runs sit at the
+    // parent's edges, so they leave no string children behind at all.
+    expect(childrenOf('<p>\n  <strong>x</strong>\n</p>')).toEqual([expect.any(Object)]);
+  });
+
+  it('keeps the space when the element is the run’s only neighbour', () => {
+    expect(childrenOf('<p>Hello <strong>x</strong></p>')).toEqual(['Hello ', expect.any(Object)]);
+    expect(childrenOf('<p><strong>x</strong> tail</p>')).toEqual([expect.any(Object), ' tail']);
+  });
+
+  describe('the bound on the rule’s known over-generosity (a pretty-printed <ul>)', () => {
+    // The shape the console's own worked example uses.
+    const UL = `<ul>
+        <li>Full HTML tag set in the <em>html</em> tier.</li>
+        <li>A trusted <a href="https://objectui.org">react tier</a> behind a flag.</li>
+        <li>Author writes markup; the platform renders it.</li>
+      </ul>`;
+
+    it('adds exactly one single-space child per inter-item gap, and none at the edges', () => {
+      const kids = childrenOf(UL);
+      expect(kids).toEqual([
+        expect.any(Object),
+        ' ',
+        expect.any(Object),
+        ' ',
+        expect.any(Object),
+      ]);
+      // The bound, stated as the thing that could have gone wrong: no string
+      // child is ever the source's newline + indentation, and no string child
+      // sits before the first item or after the last.
+      const strings = kids.filter((k): k is string => typeof k === 'string');
+      expect(strings).toEqual([' ', ' ']);
+      expect(typeof kids[0]).toBe('object');
+      expect(typeof kids[kids.length - 1]).toBe('object');
+    });
+
+    it('leaves each <li>’s own text exactly as authored', () => {
+      const items = childrenOf(UL).filter((k): k is SchemaElement => typeof k !== 'string');
+      expect(items.map(flatten)).toEqual([
+        'Full HTML tag set in the html tier.',
+        'A trusted react tier behind a flag.',
+        'Author writes markup; the platform renders it.',
+      ]);
+    });
+  });
+});
+
+/* ------------------------------------------------------------------ *
+ * The symptom as reported: rendered text, read the way the card read it.
+ * ------------------------------------------------------------------ */
+
+const Kids = ({ nodes }: { nodes?: unknown[] }) => (
+  <>{(nodes ?? []).map((n, i) => <SchemaRenderer key={i} schema={n as never} />)}</>
+);
+
+beforeAll(() => {
+  for (const tag of ['p', 'strong', 'em', 'a', 'ul', 'li'] as const) {
+    ComponentRegistry.register(
+      tag,
+      (p: never) =>
+        React.createElement(tag, {}, <Kids nodes={(p as { schema?: SchemaElement }).schema?.children} />),
+      { namespace: 'ui', isContainer: true },
+    );
+  }
+});
+
+describe('#5661 rendered: the words are no longer run together', () => {
+  /** `textContent` of the rendered tree — the card's own measurement. */
+  function renderedText(source: string): string {
+    const { tree } = parseJsx(source);
+    const host = document.createElement('div');
+    host.innerHTML = renderToStaticMarkup(<SchemaRenderer schema={tree as never} />);
+    return host.textContent ?? '';
+  }
+
+  it('renders the reported sentence with its spaces intact', () => {
+    expect(renderedText(`<p>A <strong>kind:'html'</strong> page — native HTML tags.</p>`)).toBe(
+      "A kind:'html' page — native HTML tags.",
+    );
+    // The reported rendering, stated so it cannot come back unnoticed.
+    expect(renderedText(`<p>A <strong>kind:'html'</strong> page — native HTML tags.</p>`)).not.toBe(
+      "Akind:'html'page — native HTML tags.",
+    );
+  });
+
+  it('renders both list sentences with their spaces intact', () => {
+    expect(renderedText(`<li>Full HTML tag set in the <em>html</em> tier.</li>`)).toBe(
+      'Full HTML tag set in the html tier.',
+    );
+    expect(
+      renderedText(`<li>A trusted <a href="https://objectui.org">react tier</a> behind a flag.</li>`),
+    ).toBe('A trusted react tier behind a flag.');
+  });
+});
diff --git a/packages/sdui-parser/src/parse.ts b/packages/sdui-parser/src/parse.ts
index 6469997429..cf45bd2667 100644
--- a/packages/sdui-parser/src/parse.ts
+++ b/packages/sdui-parser/src/parse.ts
@@ -173,9 +173,30 @@ class Parser {
         continue;
       }
       // text
+      //
+      // HTML collapses a whitespace run to ONE space; it does not delete it. A
+      // bare `.trim()` here deleted the space that separates a text run from an
+      // adjacent sibling element, so `A <strong>x</strong> page` compiled to
+      // `A`/`page` and rendered as `Axpage` (objectui#5661). The rule: collapse
+      // the run, then keep a single leading space only when a sibling precedes
+      // the run, and a single trailing space only when a sibling element
+      // follows it. At the parent's own start/end the edge space is still
+      // dropped, so `<p>  hi  </p>` stays `hi`. A whitespace-only run survives
+      // as one space only when it sits BETWEEN siblings — that is the bounded
+      // over-generosity of this rule inside block containers like `<ul>`,
+      // pinned in the tests.
       const text = this.readTextRun();
-      const trimmed = text.replace(/\s+/g, ' ').trim();
-      if (trimmed) children.push(trimmed);
+      const collapsed = text.replace(/\s+/g, ' ');
+      const core = collapsed.trim();
+      const afterSibling = children.length > 0;
+      const beforeElement = this.peek() === '<' && !this.src.startsWith('</', this.pos);
+      if (core) {
+        const lead = afterSibling && collapsed.startsWith(' ') ? ' ' : '';
+        const trail = beforeElement && collapsed.endsWith(' ') ? ' ' : '';
+        children.push(`${lead}${core}${trail}`);
+      } else if (collapsed && afterSibling && beforeElement) {
+        children.push(' ');
+      }
     }
     return children;
   }