diff --git a/CHANGELOG.md b/CHANGELOG.md
index 46d748d08..564d2a81b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,8 @@ notes. Entries describe what users experience, not internal refactors.
 
 ### Fixed
 
+- Local references attached while saved chat history is loading remain attached
+  when the conversation finishes restoring.
 - Reloading after a completed save restores the saved document instead of an
   older recovery snapshot or the original file.
 - Opening a copied editor tab no longer removes the original tab's reload
diff --git a/docs/explorations/2026-10-20-nightly-interaction-stability.md b/docs/explorations/2026-10-20-nightly-interaction-stability.md
new file mode 100644
index 000000000..8e92ec497
--- /dev/null
+++ b/docs/explorations/2026-10-20-nightly-interaction-stability.md
@@ -0,0 +1,94 @@
+# Nightly interaction stability
+
+The cross-browser run for PR #287 (`39249862820`) passed after retrying three
+cases. This follow-up treats those retries as evidence to investigate, rather
+than increasing their timeouts or retry budgets. PR #287 was merged before
+starting this branch, against main at `6525b804`.
+
+## Findings
+
+### Sources added during history restoration disappeared
+
+Firefox's source-reference case found the attachment row, filled its search
+field, and then lost the row while trying to open its disclosure. The trace
+shows a permanent disappearance, not a temporarily moving click target.
+
+`ReferenceSources.forget()` cleared the conversation maps while leaving the
+active entries reference detached from those maps. An attachment added during
+the asynchronous startup restore went into that detached map. Selecting the
+same conversation after restoration created an empty map and lost the new
+attachment. The correction belongs to reference ownership, rather than a
+longer click timeout or a different locator.
+
+### Historical transcript setup raced native scroll delivery
+
+WebKit's composer case set `scrollTop` to zero and immediately changed layout.
+Reading back zero did not establish that the native scroll event had run and
+updated the transcript's following state. Subsequent composer resizing could
+therefore still follow the latest message. Another nightly run (`39338214745`)
+showed the same failure for PDF, rather than DOCX.
+
+The test needs to establish a historical reader through an actual interaction
+and its visible processed-scroll signal before testing layout preservation.
+Following new content and preserving a detached reader remain separate cases.
+
+### Firefox canvas clicks preceded keyboard-capture focus
+
+The save-overlap case failed before installing its held-conversion fault:
+the first document text read remained empty after inserting `Recovery version`.
+The SDK defers its input-area focus through a zero-delay task on Firefox.
+A completed canvas click therefore does not establish that trusted text input
+will reach the document. Save setup must focus the real SDK input area and
+verify it is focused and editable, while retaining the exact document-content,
+disk-content and recovery-ownership assertions.
+
+## Boundaries and acceptance
+
+- Keep source ownership scoped to the selected conversation. Clearing existing
+  references must still invalidate captured requests; switching conversations
+  must never share attachments.
+- Preserve the production chat following and layout behavior. Synchronize the
+  E2E reader setup with actual interaction completion.
+- Preserve trusted browser input and the real editor/save/conversion path.
+  Do not patch the vendor SDK for a test preparation race.
+- Do not increase timeouts, retries, error allowlists or skip affected engines.
+- Reverse each regression against the old behavior, run focused cross-browser
+  checks without retries, then run the PR gates and complete nightly browser
+  matrix with the slow-network budgets.
+
+## Reverse validation
+
+- With the old reference ownership implementation, both parameterized unit
+  cases (`forget()` and forgetting the selected conversation) lose `New notes`
+  when the same conversation is selected again. The browser regression holds
+  initial history loading until after attach/search; releasing it loses the
+  attachment row before the fix.
+- With only the visible processed-scroll gate removed, the retained delayed
+  native-scroll scenario fails twice in WebKit: the historical offset becomes
+  `1449` instead of `0` after resizing. The corrected setup uses native Home
+  navigation and waits for the visible jump-to-latest control before resizing.
+- With only explicit SDK input focus removed from the save setup helper,
+  holding Firefox's deferred focus task leaves the exact document text empty
+  instead of `Recovery version`. The regression verifies that the task was
+  intercepted and the canvas still owned focus before attempting trusted input.
+
+These controls delay the relevant event or storage boundary, not the assertion
+deadline. The ordinary retry policy and all existing timeouts remain unchanged.
+
+## Local verification
+
+- Lint and TypeScript checks passed. The full format check also verified all
+  1511 immutable evaluation artifacts.
+- Full coverage run: 252 test files, 6801 tests passed. Statements 87.79%,
+  branches 83.94%, functions 88.77%, lines 90.25%; module thresholds passed.
+- Source unit suites: 20 passed. The gated source scenario passed twice each in
+  Firefox and WebKit, without retries. The complete sources/artifacts spec
+  passed all 8 cases in Chromium.
+- Firefox's complete save spec passed all 12 cases. The final deferred-focus
+  regression and held-recovery overlap passed together; the original overlap
+  also passed in Chromium.
+- Composer layout/navigation passed all 24 cases across four formats, three
+  repetitions and WebKit/Firefox. The delayed-scroll fault passed twice per
+  engine and once in Chromium, with retries disabled.
+
+Remote checks are recorded on the follow-up PR for its exact submitted head.
diff --git a/lib/agent-plugin/references/reference-sources.ts b/lib/agent-plugin/references/reference-sources.ts
index 5ce91391b..6ea27850e 100644
--- a/lib/agent-plugin/references/reference-sources.ts
+++ b/lib/agent-plugin/references/reference-sources.ts
@@ -40,12 +40,14 @@ export class ReferenceSources {
     if (id !== undefined) {
       const entries = this.conversations.get(id);
       entries?.clear();
-      this.conversations.delete(id);
-      if (entries === this.entries) this.entries = new Map();
+      if (entries !== this.entries) this.conversations.delete(id);
     } else {
       this.entries.clear();
-      for (const entries of this.conversations.values()) entries.clear();
-      this.conversations.clear();
+      for (const [conversation, entries] of this.conversations) {
+        entries.clear();
+        // A source attached while history restores still belongs to the selected conversation.
+        if (entries !== this.entries) this.conversations.delete(conversation);
+      }
     }
   }
   capture() {
diff --git a/test/e2e/agent-composer-ux.spec.ts b/test/e2e/agent-composer-ux.spec.ts
index 6cc770832..a637ac080 100644
--- a/test/e2e/agent-composer-ux.spec.ts
+++ b/test/e2e/agent-composer-ux.spec.ts
@@ -144,9 +144,31 @@ for (const ext of ['docx', 'xlsx', 'pptx', 'pdf'] as const) {
       await expect.poll(() => input.evaluate((el) => el.clientHeight)).toBeLessThan(narrowHeight);
       await expect(input).toHaveValue(draft);
       await expect.poll(() => log.evaluate((el) => el.scrollHeight - el.scrollTop - el.clientHeight)).toBeLessThan(3);
-      await log.evaluate((el) => {
-        el.scrollTop = 0;
-      });
+      if (ext === 'docx') {
+        // Inject delayed native scroll delivery so the readiness gate is exercised
+        // deterministically. This schedules a browser fault, not a readiness wait.
+        await log.evaluate((el) => {
+          let scheduled = false;
+          const holdScroll = (event: Event) => {
+            event.stopImmediatePropagation();
+            if (el.scrollTop !== 0 || scheduled) return;
+            scheduled = true;
+            setTimeout(() => {
+              el.removeEventListener('scroll', holdScroll, true);
+              el.dispatchEvent(new Event('scroll'));
+            }, 500);
+          };
+          el.addEventListener('scroll', holdScroll, true);
+        });
+      }
+      const scrollLatest = page.getByRole('button', { name: 'Scroll to latest' });
+      await expect(scrollLatest).toBeHidden();
+      await log.focus();
+      await log.press('Home');
+      // The offset can change before the native scroll event detaches the reader.
+      // Wait for its visible result before a resize can change transcript geometry.
+      await expect(scrollLatest).toBeVisible();
+      await expect.poll(() => log.evaluate((el) => el.scrollTop)).toBe(0);
       await resize.press('Home');
       await expect.poll(() => log.evaluate((el) => el.scrollTop)).toBe(0);
       await input.fill(draft + draft);
diff --git a/test/e2e/agent-sources-artifacts.spec.ts b/test/e2e/agent-sources-artifacts.spec.ts
index 05d380470..1d7f04494 100644
--- a/test/e2e/agent-sources-artifacts.spec.ts
+++ b/test/e2e/agent-sources-artifacts.spec.ts
@@ -92,6 +92,36 @@ test('attached reference excerpts reach only the explicitly selected AI service'
   await page.addInitScript(() => {
     localStorage.setItem('document-assistant-enabled', 'true');
     localStorage.setItem('agent_conversation_saving_v2', 'true');
+    // Hold startup hydration until a source has been attached and searched.
+    // A normal reload below must restore the captured citation without a gate.
+    if (!sessionStorage.getItem('source-test-history-released')) {
+      const open = IDBFactory.prototype.open;
+      const success = Object.getOwnPropertyDescriptor(IDBRequest.prototype, 'onsuccess')!;
+      const host = window as unknown as { releaseSourceHistory?: () => void };
+      let delayed = false;
+      IDBFactory.prototype.open = function (...args: Parameters<IDBFactory['open']>) {
+        const request = open.apply(this, args);
+        if (args[0] === 'document-ai-conversations' && !delayed) {
+          delayed = true;
+          Object.defineProperty(request, 'onsuccess', {
+            set(callback: ((this: IDBRequest, event: Event) => void) | null) {
+              success.set!.call(
+                request,
+                callback &&
+                  function (event: Event) {
+                    host.releaseSourceHistory = () => {
+                      sessionStorage.setItem('source-test-history-released', 'true');
+                      callback.call(request, event);
+                    };
+                  },
+              );
+            },
+            get: () => success.get!.call(request),
+          });
+        }
+        return request;
+      };
+    }
     localStorage.setItem(
       'agent-writing-endpoint',
       JSON.stringify({
@@ -133,6 +163,12 @@ test('attached reference excerpts reach only the explicitly selected AI service'
   await expect(page.locator('.agent-source-row')).toContainText('notes.txt');
   const sourceSearch = page.getByRole('searchbox', { name: 'Search sources', exact: true });
   await sourceSearch.fill('only this');
+  await page.waitForFunction(
+    () => typeof (window as unknown as { releaseSourceHistory?: unknown }).releaseSourceHistory === 'function',
+  );
+  await page.evaluate(() => (window as unknown as { releaseSourceHistory: () => void }).releaseSourceHistory());
+  await expect(page.locator('.agent-history-status')).toHaveText('Chat history saving is enabled on this device.');
+  await expect(page.locator('.agent-source-row')).toContainText('notes.txt');
   await page.locator('.agent-source-row summary').click();
   await expect(page.locator('.agent-source-preview mark')).toHaveText('Only this');
   await page.locator('.agent-source-row summary').click();
diff --git a/test/e2e/save-to-file.spec.ts b/test/e2e/save-to-file.spec.ts
index 2d06e833b..b827d72f9 100644
--- a/test/e2e/save-to-file.spec.ts
+++ b/test/e2e/save-to-file.spec.ts
@@ -133,6 +133,32 @@ const waitForEditorReady = (page: Page) =>
     { timeout: 90_000 },
   );
 
+/** A canvas click can precede Firefox's deferred keyboard-capture focus task. */
+const focusDocumentInput = async (page: Page) => {
+  const input = page.frameLocator('iframe[name="frameEditor"]').locator('#area_id');
+  await input.focus();
+  await expect(input).toBeFocused();
+  await expect(input).toBeEditable();
+};
+
+/** Seed save scenarios through trusted input after the canvas has selected a caret. */
+const insertDocumentText = async (page: Page, text: string) => {
+  await focusDocumentInput(page);
+  await page.keyboard.insertText(text);
+};
+
+const documentText = (page: Page) =>
+  page.evaluate(() => {
+    const win = window.__ooFrames.readyEditor() as any;
+    const logic = (win.Asc?.editor ?? win.editor).WordControl.m_oLogicDocument;
+    const paragraphs: any[] = [];
+    for (const element of logic.Content) element.GetAllParagraphs({ All: true }, paragraphs);
+    return paragraphs
+      .map((paragraph) => paragraph.GetText({ Numbering: false }))
+      .join('')
+      .trim();
+  });
+
 test.describe('saving into the document own file (real editor)', () => {
   test.describe.configure({ timeout: 240_000 });
 
@@ -267,26 +293,56 @@ test.describe('saving into the document own file (real editor)', () => {
     expect(await savedText(page)).toMatch(/first version second version/i);
   });
 
+  test('save scenario input reaches the document before deferred Firefox focus runs', async ({ page, browserName }) => {
+    test.skip(browserName !== 'firefox', 'the SDK defers keyboard-capture focus only in Firefox');
+    await page.goto('/editor?new=docx');
+    await waitForEditorReady(page);
+    const sdk = page.frameLocator('iframe[name="frameEditor"]').locator('#editor_sdk');
+    await sdk.click({ position: { x: 300, y: 200 } });
+    await expect(page.frameLocator('iframe[name="frameEditor"]').locator('#area_id')).toBeFocused();
+    await page.evaluate(() => {
+      const win = window.__ooFrames.readyEditor() as any;
+      // Ensure the canvas focus below produces a real focus event every time.
+      win.document.getElementById('area_id').focus();
+      const nativeTimeout = win.setTimeout.bind(win);
+      const deferred: (() => void)[] = [];
+      // Firefox's SDK focus handler redirects canvas focus in a zero-delay task.
+      // Hold that task so input sent before keyboard-capture focus is lost reliably.
+      win.setTimeout = (callback: TimerHandler, delay?: number, ...args: unknown[]) => {
+        if (delay === 0 && typeof callback === 'function') {
+          deferred.push(() => callback(...args));
+          return 0;
+        }
+        return nativeTimeout(callback, delay, ...args);
+      };
+      (window as any).__releaseInputFocus = () => {
+        for (const callback of deferred) callback();
+      };
+      // Intercept only tasks scheduled synchronously by this real focus event.
+      try {
+        win.document.getElementById('editor_sdk').focus();
+      } finally {
+        win.setTimeout = nativeTimeout;
+      }
+      (window as any).__deferredInputFocus = deferred.length;
+    });
+    try {
+      expect(await page.evaluate(() => (window as any).__deferredInputFocus)).toBeGreaterThan(0);
+      await expect(sdk).toBeFocused();
+      await insertDocumentText(page, 'Recovery version');
+      await expect.poll(() => documentText(page)).toBe('Recovery version');
+    } finally {
+      await page.evaluate(() => (window as any).__releaseInputFocus());
+    }
+  });
+
   test('Ctrl+S reaches disk while a recovery conversion is awaiting delivery', async ({ page }) => {
     await page.goto('/editor?new=docx');
     await waitForEditorReady(page);
     const sdk = page.frameLocator('iframe[name="frameEditor"]').locator('#editor_sdk');
     await sdk.click({ position: { x: 300, y: 200 } });
-    // This case measures save ownership, so seed its baseline atomically through
-    // the real browser input path rather than racing the SDK's initial key hooks.
-    await page.keyboard.insertText('Recovery version');
-    const documentText = () =>
-      page.evaluate(() => {
-        const win = window.__ooFrames.readyEditor() as any;
-        const logic = (win.Asc?.editor ?? win.editor).WordControl.m_oLogicDocument;
-        const paragraphs: any[] = [];
-        for (const element of logic.Content) element.GetAllParagraphs({ All: true }, paragraphs);
-        return paragraphs
-          .map((paragraph) => paragraph.GetText({ Numbering: false }))
-          .join('')
-          .trim();
-      });
-    await expect.poll(documentText).toBe('Recovery version');
+    await insertDocumentText(page, 'Recovery version');
+    await expect.poll(() => documentText(page)).toBe('Recovery version');
     await page.evaluate(() => {
       const frame = document.querySelector<HTMLIFrameElement>('iframe[name="frameEditor"]')!;
       const converter = (frame.contentWindow as any).AscCommon.x2t;
@@ -311,9 +367,10 @@ test.describe('saving into the document own file (real editor)', () => {
     });
     await page.waitForFunction(() => typeof (window as any).__releaseRecovery === 'function');
     try {
+      await focusDocumentInput(page);
       await page.keyboard.press('End');
       await page.keyboard.type(' manual version', { delay: 30 });
-      await expect.poll(documentText).toBe('Recovery version manual version');
+      await expect.poll(() => documentText(page)).toBe('Recovery version manual version');
       await page.keyboard.press('Control+s');
       await waitForWrites(page, 1);
       expect(await savedText(page)).toContain('Recovery version manual version');
diff --git a/test/unit/agent-reference-sources.test.ts b/test/unit/agent-reference-sources.test.ts
index 2effc0dcf..a211dd7d4 100644
--- a/test/unit/agent-reference-sources.test.ts
+++ b/test/unit/agent-reference-sources.test.ts
@@ -42,6 +42,26 @@ it('forgets deleted conversation attachments and invalidates their snapshots', (
   expect(current.isCurrent()).toBe(false);
   expect(sources.list()).toEqual([]);
 });
+it.each(['all', 'selected'] as const)('keeps new attachments owned after forgetting %s references', (scope) => {
+  const sources = new ReferenceSources();
+  sources.select('current');
+  sources.add({ id: 'old', connector: 'local', title: 'Old notes', text: 'private' });
+  const obsolete = sources.capture();
+  sources.forget(scope === 'all' ? undefined : 'current');
+  expect(sources.list()).toEqual([]);
+  expect(obsolete.isCurrent()).toBe(false);
+  sources.add({ id: 'new', connector: 'local', title: 'New notes', text: 'attached during restoration' });
+  const fresh = sources.capture();
+  sources.select('current');
+  expect(sources.list().map((source) => source.title)).toEqual(['New notes']);
+  expect(fresh.isCurrent()).toBe(true);
+  sources.select('other');
+  expect(sources.list()).toEqual([]);
+  sources.forget('other');
+  sources.select('current');
+  expect(sources.list().map((source) => source.title)).toEqual(['New notes']);
+  expect(fresh.isCurrent()).toBe(true);
+});
 it('releases canceled file reads and ignores their late completion', async () => {
   let complete!: (value: string) => void;
   const file = {