diff --git a/tests/e2e/test_swap_marketplace.py b/tests/e2e/test_swap_marketplace.py
new file mode 100644
index 00000000..bc09196b
--- /dev/null
+++ b/tests/e2e/test_swap_marketplace.py
@@ -0,0 +1,72 @@
+"""Overnight B2 e2e — one volunteer covers another's swap, end-to-end."""
+
+from __future__ import annotations
+
+import pytest
+
+from tests.e2e._helpers import accept_invitation, invite_token, no_js_errors, rid, signup_admin
+
+pytestmark = pytest.mark.e2e
+
+
+def _invite(page, base, name, email):
+    page.goto(f"{base}/a/people")
+    page.click("button:has-text('Invite person')")
+    page.fill("#inv_name", name)
+    page.fill("#inv_email", email)
+    page.select_option("#inv_role", "volunteer")
+    page.click("button:has-text('Send invite')")
+    page.wait_for_selector("#invite-result:has-text('Invitation sent')")
+
+
+def test_cover_a_swap_end_to_end(live_server, new_context, page, db_path):
+    base = live_server
+    a_email = f"a+{rid()}@hope.e2e"
+    b_email = f"b+{rid()}@hope.e2e"
+
+    signup_admin(page, base)
+
+    _invite(page, base, "Vol A", a_email)
+    a_page = accept_invitation(new_context(), base, invite_token(db_path, a_email))
+    _invite(page, base, "Vol B", b_email)
+    b_page = accept_invitation(new_context(), base, invite_token(db_path, b_email))
+
+    # Admin creates an event with one open role.
+    page.goto(f"{base}/a/events")
+    page.click("button:has-text('New event')")
+    page.wait_for_selector("#ev_type", state="visible")
+    page.fill("#ev_type", "Sunday 10am Service")
+    page.fill("#ev_date", "2026-06-07")
+    page.fill("#ev_start", "10:00")
+    page.fill("#ev_end", "11:30")
+    page.fill("input[name=role_name]", "volunteer")
+    page.fill("input[name=role_count]", "1")
+    page.click("button:has-text('Create event')")
+    page.wait_for_selector("#events-list:has-text('Sunday 10am Service')")
+
+    # Vol A claims it, then requests a swap.
+    a_page.goto(f"{base}/v/open")
+    a_page.wait_for_selector("#open-list:has-text('Sunday 10am Service')")
+    a_page.click("button:has-text('Claim')")
+    # Wait for the claim's HTMX swap to commit before navigating away —
+    # otherwise the assignment may not be persisted yet (CI race).
+    a_page.wait_for_selector("#open-list:has-text('No open shifts')")
+    a_page.goto(f"{base}/v/schedule")
+    a_page.click("a:has-text('Sunday 10am Service')")
+    a_page.wait_for_selector("#assignment-card")
+    a_page.click("button:has-text('Request swap')")
+    a_page.wait_for_selector("#assignment-card .status-text.swap_requested")
+
+    # Vol B covers it.
+    b_page.goto(f"{base}/v/swaps")
+    b_page.wait_for_selector("#swaps-open-list:has-text('Sunday 10am Service')")
+    b_page.click("button:has-text('Cover this shift')")
+    b_page.wait_for_selector("#swaps-open-list:has-text('No swap requests to cover')")
+
+    # B now has the shift; A no longer does.
+    b_page.goto(f"{base}/v/schedule")
+    b_page.wait_for_selector("text=Sunday 10am Service")
+    a_page.goto(f"{base}/v/schedule")
+    a_page.wait_for_selector("text=No assignments yet")
+
+    no_js_errors(b_page)
diff --git a/tests/web/test_swap_marketplace.py b/tests/web/test_swap_marketplace.py
new file mode 100644
index 00000000..fcee5372
--- /dev/null
+++ b/tests/web/test_swap_marketplace.py
@@ -0,0 +1,98 @@
+"""Overnight B2 — swap-claim marketplace."""
+
+from __future__ import annotations
+
+from datetime import datetime, timedelta
+
+from api.models import Assignment, Event
+from tests.web.conftest import seed_person
+from web.deps import SESSION_COOKIE
+
+
+def _login(client, db, *, pid, org, email):
+    seed_person(db, person_id=pid, org_id=org, email=email, roles=["volunteer"])
+    r = client.post("/auth/login", data={"email": email, "password": "WebPass123!"})
+    return r.cookies[SESSION_COOKIE]
+
+
+def _swap_setup(db, org, *, eid, requester, days=10):
+    start = datetime.utcnow() + timedelta(days=days)
+    db.add(
+        Event(
+            id=eid,
+            org_id=org,
+            type="Sunday Service",
+            start_time=start,
+            end_time=start + timedelta(hours=1),
+        )
+    )
+    db.commit()
+    a = Assignment(event_id=eid, person_id=requester, role="usher", status="swap_requested")
+    db.add(a)
+    db.commit()
+    db.refresh(a)
+    return a
+
+
+def test_swaps_requires_auth(client):
+    assert client.get("/v/swaps").status_code == 303
+
+
+def test_claim_transfers_assignment(client, db):
+    a_tok = _login(client, db, pid="sm_a", org="sm_o1", email="a@sm.test")
+    b_tok = _login(client, db, pid="sm_b", org="sm_o1", email="b@sm.test")
+    asg = _swap_setup(db, "sm_o1", eid="sm_ev", requester="sm_a")
+
+    # Requester does NOT see their own request.
+    own = client.get("/v/swaps", cookies={SESSION_COOKIE: a_tok})
+    assert "Sunday Service" not in own.text
+
+    # Other volunteer sees + covers it.
+    page = client.get("/v/swaps", cookies={SESSION_COOKIE: b_tok})
+    assert "Sunday Service" in page.text and "requested by" in page.text
+    r = client.post(f"/v/swaps/{asg.id}/claim", cookies={SESSION_COOKIE: b_tok})
+    assert r.status_code == 200
+    db.refresh(asg)
+    assert asg.person_id == "sm_b" and asg.status == "confirmed"
+    assert "No swap requests to cover" in r.text  # nothing left for B
+
+
+def test_cannot_claim_if_already_on_event(client, db):
+    seed_person(db, person_id="sm_a2", org_id="sm_o2", email="a2@sm.test", roles=["volunteer"])
+    b_tok = _login(client, db, pid="sm_b2", org="sm_o2", email="b2@sm.test")
+    asg = _swap_setup(db, "sm_o2", eid="sm_ev2", requester="sm_a2")
+    # B is already assigned to the same event.
+    db.add(Assignment(event_id="sm_ev2", person_id="sm_b2", role="greeter", status="confirmed"))
+    db.commit()
+    r = client.post(f"/v/swaps/{asg.id}/claim", cookies={SESSION_COOKIE: b_tok})
+    assert r.status_code == 400
+    assert "already on" in r.text.lower()
+    db.refresh(asg)
+    assert asg.person_id == "sm_a2"  # untouched
+
+
+def test_cannot_claim_non_swap(client, db):
+    b_tok = _login(client, db, pid="sm_b3", org="sm_o3", email="b3@sm.test")
+    seed_person(db, person_id="sm_a3", org_id="sm_o3", email="a3@sm.test", roles=["volunteer"])
+    start = datetime.utcnow() + timedelta(days=5)
+    db.add(
+        Event(
+            id="sm_ev3",
+            org_id="sm_o3",
+            type="Confirmed Ev",
+            start_time=start,
+            end_time=start + timedelta(hours=1),
+        )
+    )
+    db.commit()
+    a = Assignment(event_id="sm_ev3", person_id="sm_a3", role="usher", status="confirmed")
+    db.add(a)
+    db.commit()
+    db.refresh(a)
+    r = client.post(f"/v/swaps/{a.id}/claim", cookies={SESSION_COOKIE: b_tok})
+    assert r.status_code == 400
+
+
+def test_open_links_to_swaps(client, db):
+    tok = _login(client, db, pid="sm_v", org="sm_o4", email="v@sm.test")
+    assert 'href="/v/swaps"' in client.get("/v/open", cookies={SESSION_COOKIE: tok}).text
diff --git a/web/routers/pages.py b/web/routers/pages.py
index ef40f7bc..2302f82a 100644
--- a/web/routers/pages.py
+++ b/web/routers/pages.py
@@ -850,6 +850,65 @@ def admin_billing(
     )
 
 
+def _claimable_swaps(db: Session, person: Person) -> list[dict]:
+    """Swap-requested assignments another volunteer can cover: same org,
+    future, not the caller's own request, and not an event the caller is
+    already on. Org-scoped via the Event join."""
+    from datetime import datetime
+
+    now = datetime.utcnow()
+    rows = (
+        db.query(Assignment, Event, Person)
+        .join(Event, Assignment.event_id == Event.id)
+        .join(Person, Assignment.person_id == Person.id)
+        .filter(
+            Event.org_id == person.org_id,
+            Assignment.status == "swap_requested",
+            Assignment.person_id != person.id,
+            Event.start_time >= now,
+        )
+        .order_by(Event.start_time.asc())
+        .all()
+    )
+    mine = {
+        a.event_id
+        for a in db.query(Assignment)
+        .join(Event, Assignment.event_id == Event.id)
+        .filter(Event.org_id == person.org_id, Assignment.person_id == person.id)
+        .all()
+    }
+    return [
+        {
+            "assignment_id": a.id,
+            "event_type": e.type,
+            "when": e.start_time.strftime("%a %d %b %Y · %H:%M") if e.start_time else "",
+            "role": a.role,
+            "requested_by": p.name,
+        }
+        for a, e, p in rows
+        if e.id not in mine
+    ]
+
+
+@router.get("/v/swaps", response_class=HTMLResponse)
+def volunteer_swaps_open(
+    request: Request,
+    person: Person = Depends(get_session_user),
+    db: Session = Depends(get_db),
+):
+    from web.app import templates
+
+    return templates.TemplateResponse(
+        request,
+        "volunteer/swaps_open.html",
+        {
+            "person": person,
+            "active_tab": "schedule",
+            "swaps": _claimable_swaps(db, person),
+        },
+    )
+
+
 def _swap_requests(db: Session, org_id: str) -> list[dict]:
     """Assignments the volunteer flagged for swap, org-scoped via the
     Event join."""
diff --git a/web/routers/partials.py b/web/routers/partials.py
index c7053ab1..8636e7d1 100644
--- a/web/routers/partials.py
+++ b/web/routers/partials.py
@@ -77,6 +77,7 @@
 from web.routers.pages import (
     NOTIF_TYPES,
     RRULE_PRESETS,
+    _claimable_swaps,
     _constraints,
     _email_prefs,
     _event_assignments,
@@ -245,6 +246,75 @@ def open_claim(
     return _open_list(request, person, db)
 
 
+# ── Volunteer: swap-claim marketplace ────────────────────────────────
+
+
+def _swaps_open_list(request: Request, person: Person, db: Session, *, error=None):
+    from web.app import templates
+
+    return templates.TemplateResponse(
+        request,
+        "partials/swaps_open_list.html",
+        {"swaps": _claimable_swaps(db, person), "error": error},
+        status_code=400 if error else 200,
+    )
+
+
+@router.post("/v/swaps/{assignment_id}/claim", response_class=HTMLResponse)
+def swap_claim(
+    request: Request,
+    assignment_id: int,
+    person: Person = Depends(get_session_user),
+    db: Session = Depends(get_db),
+):
+    """Cover a teammate's swap: transfer the assignment to the claimer.
+    Re-validated server-side (org, still swap_requested, not own, future,
+    claimer not already on the event) — org-scoped direct write."""
+    from datetime import datetime
+
+    a = (
+        db.query(Assignment)
+        .join(Event, Assignment.event_id == Event.id)
+        .filter(
+            Event.org_id == person.org_id,
+            Assignment.id == assignment_id,
+            Assignment.status == "swap_requested",
+        )
+        .first()
+    )
+    if a is None:
+        return _swaps_open_list(
+            request, person, db, error="That swap is no longer available."
+        )
+    if a.person_id == person.id:
+        return _swaps_open_list(
+            request, person, db, error="That's your own swap request."
+        )
+    ev = db.query(Event).filter(Event.id == a.event_id).first()
+    if ev is None or (ev.start_time and ev.start_time < datetime.utcnow()):
+        return _swaps_open_list(request, person, db, error="That event has passed.")
+    already = (
+        db.query(Assignment)
+        .join(Event, Assignment.event_id == Event.id)
+        .filter(
+            Event.org_id == person.org_id,
+            Assignment.event_id == a.event_id,
+            Assignment.person_id == person.id,
+        )
+        .first()
+    )
+    if already is not None:
+        return _swaps_open_list(
+            request, person, db, error="You're already on that event."
+        )
+
+    a.person_id = person.id
+    a.status = "confirmed"
+    a.decline_reason = None
+    db.commit()
+    return _swaps_open_list(request, person, db)
+
+
 # ── Availability: time-off ───────────────────────────────────────────
 
 
diff --git a/web/templates/partials/swaps_open_list.html b/web/templates/partials/swaps_open_list.html
new file mode 100644
index 00000000..2f999966
--- /dev/null
+++ b/web/templates/partials/swaps_open_list.html
@@ -0,0 +1,27 @@
+{# Swap requests another volunteer can cover. #swaps-open-list. #}
+<div id="swaps-open-list">
+  {% if error %}
+  <div class="form-error" role="alert">{{ error }}</div>
+  <div class="spacer-12"></div>
+  {% endif %}
+
+  {% if not swaps %}
+  <div class="empty">No swap requests to cover right now.</div>
+  {% else %}
+  {% for s in swaps %}
+  <div class="card" style="margin-bottom:12px">
+    <div class="row-title">{{ s.event_type }}</div>
+    <div class="row-sub">{{ s.when }}</div>
+    <div style="margin-top:6px;display:flex;gap:6px;align-items:center;flex-wrap:wrap">
+      {% if s.role %}<span class="role-chip">{{ s.role }}</span>{% endif %}
+      <span class="row-sub">requested by {{ s.requested_by }}</span>
+    </div>
+    <div class="spacer-12"></div>
+    <form hx-post="/v/swaps/{{ s.assignment_id }}/claim"
+          hx-target="#swaps-open-list" hx-swap="outerHTML" style="margin:0">
+      <button class="btn btn-go" type="submit">Cover this shift</button>
+    </form>
+  </div>
+  {% endfor %}
+  {% endif %}
+</div>
diff --git a/web/templates/volunteer/open.html b/web/templates/volunteer/open.html
index 0fd8cda4..b0f07117 100644
--- a/web/templates/volunteer/open.html
+++ b/web/templates/volunteer/open.html
@@ -10,6 +10,8 @@
 <div class="page-title">Open shifts</div>
 <div class="scroll">
   {% include "partials/open_list.html" %}
+  <div class="spacer-18"></div>
+  <a class="btn btn-secondary" href="/v/swaps">Cover a teammate's swap →</a>
 </div>
 {% set tabs = [
   ('/v/schedule', '▦', 'Schedule', 'schedule'),
diff --git a/web/templates/volunteer/swaps_open.html b/web/templates/volunteer/swaps_open.html
new file mode 100644
index 00000000..73799086
--- /dev/null
+++ b/web/templates/volunteer/swaps_open.html
@@ -0,0 +1,20 @@
+{% extends "base.html" %}
+{% block title %}Cover a swap · SignUpFlow{% endblock %}
+{% block body %}
+<div class="nav">
+  <a class="nav-back" href="/v/open">‹ Open shifts</a>
+  <form method="post" action="/auth/logout" style="margin:0">
+    <button class="nav-action" type="submit">Sign out</button>
+  </form>
+</div>
+<div class="page-title">Cover a swap</div>
+<div class="scroll">
+  {% include "partials/swaps_open_list.html" %}
+</div>
+{% set tabs = [
+  ('/v/schedule', '▦', 'Schedule', 'schedule'),
+  ('/v/availability', '◷', 'Availability', 'availability'),
+  ('/v/profile', '◍', 'Profile', 'profile'),
+] %}
+{% include "_nav.html" %}
+{% endblock %}