diff --git a/frontend/src/stimulus/controllers/refresh-on-form-changes.controller.spec.ts b/frontend/src/stimulus/controllers/refresh-on-form-changes.controller.spec.ts
new file mode 100644
index 000000000000..bdb14bfd63b1
--- /dev/null
+++ b/frontend/src/stimulus/controllers/refresh-on-form-changes.controller.spec.ts
@@ -0,0 +1,246 @@
+//-- copyright
+// OpenProject is an open source project management software.
+// Copyright (C) the OpenProject GmbH
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License version 3.
+//
+// OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+// Copyright (C) 2006-2013 Jean-Philippe Lang
+// Copyright (C) 2010-2013 the ChiliProject Team
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+// See COPYRIGHT and LICENSE files for more details.
+//++
+
+import { waitFor } from '@testing-library/dom';
+import { vi, type Mock } from 'vitest';
+
+import { setupStimulusTest, type StimulusTestContext } from 'core-stimulus/test-helpers';
+import type RefreshOnFormChangesControllerType from './refresh-on-form-changes.controller';
+import { serializeFormQuery } from './refresh-on-form-changes.controller';
+
+describe('Refresh on form changes controller', () => {
+  let ctx:StimulusTestContext;
+  let RefreshOnFormChangesController:typeof RefreshOnFormChangesControllerType;
+  let fetchSpy:Mock;
+  let renderStreamMessage:Mock;
+  let originalTurbo:typeof window.Turbo;
+
+  beforeAll(async () => {
+    ({ default: RefreshOnFormChangesController } = await import('./refresh-on-form-changes.controller'));
+  });
+
+  beforeEach(async () => {
+    fetchSpy = vi.fn().mockImplementation(() => Promise.resolve(turboStreamResponse()));
+    renderStreamMessage = vi.fn().mockResolvedValue(undefined);
+
+    originalTurbo = window.Turbo;
+    window.Turbo = {
+      ...originalTurbo,
+      fetch: fetchSpy,
+      renderStreamMessage,
+    } as typeof window.Turbo;
+    vi.spyOn(window, 'fetch').mockImplementation(fetchSpy);
+
+    ctx = await setupStimulusTest({
+      controllers: { 'refresh-on-form-changes': RefreshOnFormChangesController },
+    });
+  });
+
+  afterEach(() => {
+    ctx.dispose();
+    window.Turbo = originalTurbo;
+    vi.restoreAllMocks();
+  });
+
+  function turboStreamResponse(html = '<turbo-stream action="update" target="sprint-dialog-form"></turbo-stream>') {
+    return new Response(html, {
+      status: 200,
+      headers: { 'Content-Type': 'text/vnd.turbo-stream.html' },
+    });
+  }
+
+  async function renderForm() {
+    await ctx.mount(`
+      <form data-controller="refresh-on-form-changes"
+            data-refresh-on-form-changes-target="form"
+            data-refresh-on-form-changes-turbo-stream-url-value="/refresh">
+        <input name="sprint[name]" value="Created sprint">
+        <textarea name="sprint[goal][text]">Deliver the first MVP scope.</textarea>
+      </form>
+    `);
+
+    return ctx.getController<RefreshOnFormChangesControllerType>('refresh-on-form-changes');
+  }
+
+  it('requests a turbo stream refresh with the current form data as query params', async () => {
+    const controller = await renderForm();
+
+    controller.triggerTurboStream();
+
+    await waitFor(() => {
+      expect(fetchSpy).toHaveBeenCalled();
+    });
+
+    const [url, init] = fetchSpy.mock.calls[0] as [string, RequestInit];
+    const parsedUrl = new URL(url, window.location.origin);
+
+    expect(parsedUrl.pathname).toBe('/refresh');
+    expect(parsedUrl.searchParams.get('sprint[name]')).toBe('Created sprint');
+    expect(parsedUrl.searchParams.get('sprint[goal][text]')).toBe('Deliver the first MVP scope.');
+    expect(init).toEqual(expect.objectContaining({
+      method: 'GET',
+      credentials: 'same-origin',
+      headers: expect.objectContaining({
+        Accept: 'text/vnd.turbo-stream.html, text/html, application/xhtml+xml',
+        'X-Requested-With': 'XMLHttpRequest',
+      }) as HeadersInit,
+    }));
+    await waitFor(() => {
+      expect(renderStreamMessage).toHaveBeenCalledWith(
+        '<turbo-stream action="update" target="sprint-dialog-form"></turbo-stream>',
+      );
+    });
+  });
+
+  it('aborts an in-flight refresh before starting the next one', async () => {
+    const controller = await renderForm();
+    let firstReject!:(error:DOMException) => void;
+    let firstSignal:AbortSignal|undefined;
+
+    fetchSpy
+      .mockImplementationOnce((_url:string, init:RequestInit) => {
+        firstSignal = init.signal ?? undefined;
+
+        return new Promise<Response>((_resolve, reject) => {
+          firstReject = reject;
+        });
+      })
+      .mockResolvedValueOnce(turboStreamResponse());
+
+    controller.triggerTurboStream();
+    await waitFor(() => {
+      expect(fetchSpy).toHaveBeenCalledTimes(1);
+    });
+
+    controller.triggerTurboStream();
+    await waitFor(() => {
+      expect(fetchSpy).toHaveBeenCalledTimes(2);
+    });
+
+    expect(firstSignal?.aborted).toBe(true);
+    firstReject(new DOMException('The operation was aborted.', 'AbortError'));
+
+    await waitFor(() => {
+      expect(renderStreamMessage).toHaveBeenCalledOnce();
+    });
+  });
+
+  it('aborts an in-flight refresh when disconnected', async () => {
+    const controller = await renderForm();
+    let signal:AbortSignal|undefined;
+
+    fetchSpy.mockImplementationOnce((_url:string, init:RequestInit) => {
+      signal = init.signal ?? undefined;
+
+      return new Promise<Response>((resolve) => {
+        void resolve;
+      });
+    });
+
+    controller.triggerTurboStream();
+    await waitFor(() => {
+      expect(fetchSpy).toHaveBeenCalledOnce();
+    });
+
+    ctx.container.querySelector('form')!.remove();
+    await ctx.nextFrame();
+
+    expect(signal?.aborted).toBe(true);
+  });
+
+  it('coalesces rapid refresh requests into a single request with the latest form data', async () => {
+    const controller = await renderForm();
+    const goalInput = ctx.container.querySelector<HTMLTextAreaElement>('[name="sprint[goal][text]"]')!;
+
+    controller.triggerTurboStream();
+    goalInput.value = 'Updated goal';
+    controller.triggerTurboStream();
+
+    await waitFor(() => {
+      expect(fetchSpy).toHaveBeenCalledOnce();
+    });
+    const [url] = fetchSpy.mock.calls[0] as [string, RequestInit];
+    const parsedUrl = new URL(url, window.location.origin);
+
+    expect(parsedUrl.searchParams.get('sprint[goal][text]')).toBe('Updated goal');
+  });
+
+  describe('serializeFormQuery', () => {
+    function buildForm(innerHtml:string):HTMLFormElement {
+      const form = document.createElement('form');
+      form.innerHTML = innerHtml;
+      return form;
+    }
+
+    it('serializes string form fields into a query string', () => {
+      const form = buildForm(`
+        <input name="sprint[name]" value="Created sprint">
+        <textarea name="sprint[goal][text]">Deliver the first MVP scope.</textarea>
+      `);
+
+      const params = new URLSearchParams(serializeFormQuery(form));
+
+      expect(params.get('sprint[name]')).toBe('Created sprint');
+      expect(params.get('sprint[goal][text]')).toBe('Deliver the first MVP scope.');
+    });
+
+    it('omits file inputs so File values never reach the query string', () => {
+      const form = buildForm(`
+        <input name="sprint[name]" value="Created sprint">
+        <input type="file" name="sprint[attachment]">
+      `);
+      const fileInput = form.querySelector<HTMLInputElement>('[name="sprint[attachment]"]')!;
+      const transfer = new DataTransfer();
+      transfer.items.add(new File(['data'], 'report.pdf', { type: 'application/pdf' }));
+      fileInput.files = transfer.files;
+
+      const params = new URLSearchParams(serializeFormQuery(form));
+
+      expect(params.has('sprint[attachment]')).toBe(false);
+      expect(params.get('sprint[name]')).toBe('Created sprint');
+    });
+  });
+
+  it('swallows abort errors but logs other request errors', async () => {
+    const controller = await renderForm();
+    const consoleError = vi.spyOn(console, 'error').mockImplementation(() => undefined);
+
+    fetchSpy.mockRejectedValueOnce(new DOMException('The operation was aborted.', 'AbortError'));
+    controller.triggerTurboStream();
+    await waitFor(() => {
+      expect(fetchSpy).toHaveBeenCalledOnce();
+    });
+    expect(consoleError).not.toHaveBeenCalled();
+
+    fetchSpy.mockRejectedValueOnce(new Error('network down'));
+    controller.triggerTurboStream();
+    await waitFor(() => {
+      expect(consoleError).toHaveBeenCalledWith(new Error('network down'));
+    });
+  });
+});
diff --git a/frontend/src/stimulus/controllers/refresh-on-form-changes.controller.ts b/frontend/src/stimulus/controllers/refresh-on-form-changes.controller.ts
index 8d4d068f55ce..6f5338236c2e 100644
--- a/frontend/src/stimulus/controllers/refresh-on-form-changes.controller.ts
+++ b/frontend/src/stimulus/controllers/refresh-on-form-changes.controller.ts
@@ -28,10 +28,29 @@
  * ++
  */
 
-import { ApplicationController } from 'stimulus-use';
-import { renderStreamMessage } from '@hotwired/turbo';
+import { ApplicationController, useDebounce } from 'stimulus-use';
+import { FetchRequest } from '@rails/request.js';
+
+const TURBO_STREAM_REFRESH_DELAY = 50;
+
+// Serialize a form's fields into a query string. URLSearchParams does not accept
+// a FormData object whose entries may hold File values, so copy the string
+// entries across explicitly, dropping any file inputs.
+export function serializeFormQuery(form:HTMLFormElement):string {
+  const params = new URLSearchParams();
+  new FormData(form).forEach((value, key) => {
+    if (typeof value === 'string') {
+      params.append(key, value);
+    }
+  });
+  return params.toString();
+}
 
 export default class RefreshOnFormChangesController extends ApplicationController {
+  static debounces = [
+    { name: 'performTurboStreamRefresh', wait: TURBO_STREAM_REFRESH_DELAY },
+  ];
+
   static targets = [
     'form',
   ];
@@ -46,23 +65,48 @@ export default class RefreshOnFormChangesController extends ApplicationControlle
   declare refreshUrlValue:string;
   declare turboStreamUrlValue:string;
 
+  private abortController:AbortController|null = null;
+
+  connect():void {
+    useDebounce(this);
+  }
+
+  disconnect():void {
+    this.abortController?.abort();
+    this.abortController = null;
+  }
+
   triggerReload():void {
-    window.location.href = `${this.refreshUrlValue}?${this.getSerializedFormData()}`;
+    window.location.replace(`${this.refreshUrlValue}?${serializeFormQuery(this.formTarget)}`);
   }
 
-  async triggerTurboStream():Promise<void> {
-    await fetch(`${this.turboStreamUrlValue}?${this.getSerializedFormData()}`, {
-      headers: {
-        Accept: 'text/vnd.turbo-stream.html',
-      },
-    }).then((r) => r.text())
-      .then((html) => renderStreamMessage(html));
+  triggerTurboStream():void {
+    void this.performTurboStreamRefresh();
   }
 
-  private getSerializedFormData():string {
-    // without the cast to undefined, the URLSearchParams constructor will
-    // not accept the FormData object.
-    const formData = new FormData(this.formTarget) as unknown as undefined;
-    return new URLSearchParams(formData).toString();
+  private async performTurboStreamRefresh():Promise<void> {
+    // Cancel any refresh still in flight so a slower, earlier response cannot
+    // arrive last and overwrite the form with stale state (e.g. a half-entered
+    // date range clobbering the completed one).
+    this.abortController?.abort();
+    const abortController = new AbortController();
+    this.abortController = abortController;
+
+    try {
+      const request = new FetchRequest('get', this.turboStreamUrlValue, {
+        query: new FormData(this.formTarget),
+        responseKind: 'turbo-stream',
+        signal: abortController.signal,
+      });
+      await request.perform();
+    } catch (error) {
+      if (!(error instanceof DOMException && error.name === 'AbortError')) {
+        console.error(error);
+      }
+    } finally {
+      if (this.abortController === abortController) {
+        this.abortController = null;
+      }
+    }
   }
 }
diff --git a/modules/backlogs/app/components/backlogs/sprint_form_component.rb b/modules/backlogs/app/components/backlogs/sprint_form_component.rb
index 2bed573eda4f..1345eec466d3 100644
--- a/modules/backlogs/app/components/backlogs/sprint_form_component.rb
+++ b/modules/backlogs/app/components/backlogs/sprint_form_component.rb
@@ -77,7 +77,7 @@ def banner_text
     end
 
     def goal
-      sprint.goals.find_or_initialize_by(project:)
+      sprint.goal_for(project) || sprint.goals.build(project:)
     end
 
     def goal_label
diff --git a/modules/backlogs/app/models/sprint.rb b/modules/backlogs/app/models/sprint.rb
index a06f17792446..c2926f939bac 100644
--- a/modules/backlogs/app/models/sprint.rb
+++ b/modules/backlogs/app/models/sprint.rb
@@ -113,11 +113,7 @@ def visible_to?(project)
   end
 
   def goal_for(project)
-    if goals.loaded?
-      goals.find { |goal| goal.project_id == project.id }
-    else
-      goals.find_by(project:)
-    end
+    goals.find { |goal| goal.project_id == project.id }
   end
 
   def goal_text_for(project)
diff --git a/modules/backlogs/spec/features/backlogs/create_spec.rb b/modules/backlogs/spec/features/backlogs/create_spec.rb
index 8fdadb30f878..b1b14b90465b 100644
--- a/modules/backlogs/spec/features/backlogs/create_spec.rb
+++ b/modules/backlogs/spec/features/backlogs/create_spec.rb
@@ -104,7 +104,11 @@
       within_dialog "New sprint" do
         fill_in "Sprint name", with: "Created sprint"
         fill_in "Start date", with: start_date_fmt
-        fill_in "Finish date", with: finish_date_fmt
+        fill_in("Finish date", with: finish_date_fmt).send_keys(:tab)
+        # Wait for the date-triggered form refresh to settle before filling the
+        # goal, otherwise the in-flight refresh re-renders the form and discards
+        # the goal that was just typed.
+        expect(page).to have_field "Duration", with: "16 days", readonly: true
         fill_in "Sprint goal", with: "Deliver the first MVP scope."
 
         click_on "Create"
@@ -114,6 +118,24 @@
       planning_page.expect_sprint_heading_with_goal("Created sprint", "Deliver the first MVP scope.")
     end
 
+    it "keeps the sprint goal when entering the dates (regression #AGILE-301)" do
+      planning_page.visit!
+
+      planning_page.open_create_sprint_dialog
+
+      within_dialog "New sprint" do
+        fill_in "Sprint name", with: "Created sprint"
+        fill_in "Sprint goal", with: "Deliver the first MVP scope."
+
+        fill_in "Start date", with: start_date_fmt
+        fill_in("Finish date", with: finish_date_fmt).send_keys(:tab)
+
+        # Entering the dates triggers a form refresh; it must not wipe the goal.
+        expect(page).to have_field "Duration", with: "16 days", readonly: true
+        expect(page).to have_field "Sprint goal", with: "Deliver the first MVP scope."
+      end
+    end
+
     it "previews the sprint duration when changing the dates" do
       planning_page.visit!
 
@@ -123,7 +145,7 @@
         expect(page).to have_field "Duration", with: "", readonly: true
 
         page.fill_in "Start date", with: start_date_fmt
-        page.fill_in "Finish date", with: finish_date_fmt
+        page.fill_in("Finish date", with: finish_date_fmt).send_keys(:tab)
 
         expect(page).to have_field "Duration", with: "16 days", readonly: true
       end
@@ -155,7 +177,8 @@
 
         within_dialog "New sprint" do
           page.fill_in "Start date", with: start_date_fmt
-          page.fill_in "Finish date", with: too_early_finish_date.strftime("%Y-%m-%d")
+          page.fill_in("Finish date", with: too_early_finish_date.strftime("%Y-%m-%d"))
+              .send_keys(:tab)
 
           # Shows duration as zero if finish date is before start date:
           expect(page).to have_field "Duration", with: "0 days", readonly: true
diff --git a/modules/backlogs/spec/models/sprint_spec.rb b/modules/backlogs/spec/models/sprint_spec.rb
index fe59d21ad020..8b5c3e2f86c4 100644
--- a/modules/backlogs/spec/models/sprint_spec.rb
+++ b/modules/backlogs/spec/models/sprint_spec.rb
@@ -443,6 +443,13 @@
       other_project = create(:project)
       expect(sprint.goal_for(other_project)).to be_nil
     end
+
+    it "returns an in-memory goal for an unsaved sprint" do
+      sprint = build(:sprint, project:)
+      sprint_goal = sprint.goals.build(project:, text: "Ship dashboard")
+
+      expect(sprint.goal_for(project)).to eq(sprint_goal)
+    end
   end
 
   describe "#goal_text_for" do