diff --git a/apps/backend/api/v1/projects.py b/apps/backend/api/v1/projects.py
index 6bb5ad9..ec885ba 100644
--- a/apps/backend/api/v1/projects.py
+++ b/apps/backend/api/v1/projects.py
@@ -669,6 +669,18 @@ async def list_project_releases_endpoint(
     project_id: uuid.UUID,
     page: int = Query(default=1, ge=1),
     size: int = Query(default=20, ge=1, le=100),
+    release: str | None = Query(
+        default=None,
+        max_length=100,
+        description=(
+            "Optional version label filter (e.g. '4.0'), matched exactly against "
+            "the scan's ``metadata.release`` with surrounding whitespace trimmed. "
+            "This is the lookup for \"which snapshot is version 4.0?\": a label "
+            "identifies at most one live snapshot, so the filtered list carries "
+            "one row whose ``scan_id`` you then pin on the detail endpoints via "
+            "``?scan_id=``. An unknown label returns an empty list, not a 404."
+        ),
+    ),
     session: AsyncSession = Depends(get_db),
     actor: CurrentUser = Depends(require_role("developer")),
 ) -> Response:
@@ -682,6 +694,7 @@ async def list_project_releases_endpoint(
             actor=actor,
             page=page,
             size=size,
+            release=release,
         )
     except ProjectError as exc:
         return _problem_for_project_error(request, exc)
diff --git a/apps/backend/services/release_snapshot_service.py b/apps/backend/services/release_snapshot_service.py
index f2c593d..22d1c9a 100644
--- a/apps/backend/services/release_snapshot_service.py
+++ b/apps/backend/services/release_snapshot_service.py
@@ -53,7 +53,7 @@
 from typing import Any
 
 import structlog
-from sqlalchemy import String, case, cast, func, literal, select
+from sqlalchemy import String, and_, case, cast, func, literal, select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from core.authz import assert_team_access
@@ -150,6 +150,7 @@ async def _paged_succeeded_scans(
     project_id: uuid.UUID,
     page: int,
     size: int,
+    release: str | None = None,
 ) -> tuple[list[Scan], int]:
     """Return ``(page_of_succeeded_scans, total)`` newest-first.
 
@@ -157,8 +158,18 @@ async def _paged_succeeded_scans(
     pages and covered by ``ix_scans_project_created_at``) and one count. We load
     the ORM ``Scan`` rows so we can read ``scan_metadata['release']`` without a
     second round-trip.
+
+    ``release`` narrows the listing to snapshots carrying that exact version
+    label. This is how a caller answers "which snapshot is 4.0?" without paging
+    the project's whole history: since a labelled scan supersedes any earlier
+    scan claiming the same label, and superseded rows are excluded below, a
+    label match yields at most one row. The comparison trims both sides — the
+    stored label is trimmed at write time and the supersede rule compares
+    trimmed — and it is served by ``ix_scans_project_release_label``, whose key
+    is the trimmed expression.
     """
     offset = (page - 1) * size
+    label = release.strip() if release is not None else None
 
     # scan-retention: hide superseded snapshots. A superseded scan lost its ref
     # slot to a newer winner (and carries no release label — retire never
@@ -180,6 +191,15 @@ async def _paged_succeeded_scans(
         .where(cast(Scan.status, String) == "succeeded")
         .where(Scan.superseded_at.is_(None))
     )
+    if label:
+        # Applied to both statements so `total` describes the filtered set — a
+        # caller paging a label filter must not be told there are 40 matches.
+        label_match = and_(
+            func.jsonb_typeof(Scan.scan_metadata["release"]) == "string",
+            func.btrim(Scan.scan_metadata["release"].astext) == label,
+        )
+        items_stmt = items_stmt.where(label_match)
+        count_stmt = count_stmt.where(label_match)
 
     items_result = await session.execute(items_stmt)
     count_result = await session.execute(count_stmt)
@@ -322,6 +342,7 @@ async def list_release_snapshots(
     actor: CurrentUser,
     page: int = 1,
     size: int = 20,
+    release: str | None = None,
 ) -> tuple[list[dict[str, Any]], int]:
     """List a project's release snapshots (succeeded scans), newest-first.
 
@@ -329,6 +350,12 @@ async def list_release_snapshots(
     :class:`schemas.release_snapshot.ReleaseSnapshot`. ``total`` is the count of
     succeeded scans before pagination.
 
+    ``release`` narrows the listing to the snapshot carrying that version label,
+    which is how "give me version 4.0" is answered — the caller reads the row's
+    ``scan_id`` and pins it on the detail endpoints via ``?scan_id=``. An
+    unknown label is an empty 200, not a 404: absence of a version is a normal
+    answer, and 404 here would be indistinguishable from "no such project".
+
     Authorization mirrors :func:`get_project_overview`: ``ProjectNotFound`` (404)
     for a missing project, ``ProjectForbidden`` (403) for a non-member (super_admin
     bypasses). A project with no succeeded scan returns ``([], 0)`` — an empty
@@ -356,7 +383,7 @@ async def list_release_snapshots(
     )
 
     scans, total = await _paged_succeeded_scans(
-        session, project_id=project_id, page=page, size=size
+        session, project_id=project_id, page=page, size=size, release=release
     )
     if not scans:
         return [], total
diff --git a/apps/backend/tests/integration/test_release_snapshots_api.py b/apps/backend/tests/integration/test_release_snapshots_api.py
index 12bd3a3..ba7a0b4 100644
--- a/apps/backend/tests/integration/test_release_snapshots_api.py
+++ b/apps/backend/tests/integration/test_release_snapshots_api.py
@@ -342,6 +342,97 @@ async def test_releases_lists_succeeded_scans_newest_first_with_summaries(client
     assert older_row["risk_score"] == 83.3
 
 
+async def test_releases_release_filter_returns_only_that_version(client) -> None:
+    # "Which snapshot is 4.0?" — the whole point of attaching a version label.
+    team, user = await _seed_team_with_user(client)
+    project_id = await _seed_empty_project(client, team_id=team.id)
+    headers = _bearer_for(user)
+    base = datetime(2026, 5, 20, tzinfo=UTC)
+
+    tagged = await _seed_succeeded_scan(
+        client, project_id=project_id, created_at=base, release="4.0"
+    )
+    await _seed_succeeded_scan(
+        client, project_id=project_id, created_at=base + timedelta(days=1), release="4.1"
+    )
+    await _seed_succeeded_scan(
+        client, project_id=project_id, created_at=base + timedelta(days=2)
+    )
+
+    unfiltered = await client.get(f"/v1/projects/{project_id}/releases", headers=headers)
+    assert unfiltered.json()["total"] == 3
+
+    filtered = await client.get(
+        f"/v1/projects/{project_id}/releases", headers=headers, params={"release": "4.0"}
+    )
+    assert filtered.status_code == 200, filtered.text
+    body = filtered.json()
+    # `total` must describe the FILTERED set — a caller paging the filter must
+    # not be told there are three matches.
+    assert body["total"] == 1
+    assert [row["scan_id"] for row in body["items"]] == [str(tagged)]
+    assert body["items"][0]["release"] == "4.0"
+
+
+async def test_releases_release_filter_trims_both_sides(client) -> None:
+    team, user = await _seed_team_with_user(client)
+    project_id = await _seed_empty_project(client, team_id=team.id)
+    headers = _bearer_for(user)
+    tagged = await _seed_succeeded_scan(
+        client,
+        project_id=project_id,
+        created_at=datetime(2026, 5, 20, tzinfo=UTC),
+        release=" 4.0 ",
+    )
+
+    for query in ("4.0", "  4.0  "):
+        response = await client.get(
+            f"/v1/projects/{project_id}/releases",
+            headers=headers,
+            params={"release": query},
+        )
+        assert response.status_code == 200, response.text
+        assert [row["scan_id"] for row in response.json()["items"]] == [str(tagged)]
+
+
+async def test_releases_unknown_release_is_empty_200_not_404(client) -> None:
+    # Absence of a version is a normal answer. A 404 here would be
+    # indistinguishable from "no such project".
+    team, user = await _seed_team_with_user(client)
+    project_id = await _seed_empty_project(client, team_id=team.id)
+    headers = _bearer_for(user)
+    await _seed_succeeded_scan(
+        client,
+        project_id=project_id,
+        created_at=datetime(2026, 5, 20, tzinfo=UTC),
+        release="4.0",
+    )
+
+    response = await client.get(
+        f"/v1/projects/{project_id}/releases",
+        headers=headers,
+        params={"release": "9.9"},
+    )
+    assert response.status_code == 200, response.text
+    assert response.json()["items"] == []
+    assert response.json()["total"] == 0
+
+
+async def test_releases_release_filter_does_not_cross_projects(client) -> None:
+    team, user = await _seed_team_with_user(client)
+    mine = await _seed_empty_project(client, team_id=team.id)
+    theirs = await _seed_empty_project(client, team_id=team.id)
+    headers = _bearer_for(user)
+    base = datetime(2026, 5, 20, tzinfo=UTC)
+    await _seed_succeeded_scan(client, project_id=theirs, created_at=base, release="4.0")
+
+    response = await client.get(
+        f"/v1/projects/{mine}/releases", headers=headers, params={"release": "4.0"}
+    )
+    assert response.status_code == 200, response.text
+    assert response.json()["items"] == []
+
+
 async def test_releases_empty_when_no_succeeded_scan(client) -> None:
     team, user = await _seed_team_with_user(client)
     project_id = await _seed_empty_project(client, team_id=team.id)
diff --git a/apps/backend/tests/unit/openapi_endpoints.json b/apps/backend/tests/unit/openapi_endpoints.json
index 70a785e..6cde2fa 100644
--- a/apps/backend/tests/unit/openapi_endpoints.json
+++ b/apps/backend/tests/unit/openapi_endpoints.json
@@ -303,6 +303,7 @@
   "GET /v1/projects/{project_id}/releases": [
     "page",
     "project_id",
+    "release",
     "size"
   ],
   "GET /v1/projects/{project_id}/remediation/pull-requests": [
diff --git a/apps/frontend/src/features/projects/api/releasesApi.ts b/apps/frontend/src/features/projects/api/releasesApi.ts
index 870294f..8043184 100644
--- a/apps/frontend/src/features/projects/api/releasesApi.ts
+++ b/apps/frontend/src/features/projects/api/releasesApi.ts
@@ -8,7 +8,7 @@
  * needs to pick a snapshot to inspect (risk score, severity summary, gate
  * verdict, component count).
  *
- *   - GET /v1/projects/{id}/releases?page=&size= → ReleaseListResponse
+ *   - GET /v1/projects/{id}/releases?page=&size=&release= → ReleaseListResponse
  *
  * The wire types mirror the backend's `ReleaseSnapshot` 1:1 (snake_case).
  * `release` is frequently `null` (the scan was triggered without a version
@@ -77,6 +77,13 @@ export interface ListReleasesParams {
   page?: number;
   /** Page size (server default applies when omitted). */
   size?: number;
+  /**
+   * Exact version-label filter (e.g. "4.0"). A label identifies at most one
+   * live release, so this is the "which snapshot is 4.0?" lookup rather than a
+   * search. Whitespace is trimmed on both sides; an unknown label yields an
+   * empty list, not an error.
+   */
+  release?: string;
 }
 
 export async function listProjectReleases(
@@ -86,6 +93,9 @@ export async function listProjectReleases(
   const query: Record<string, unknown> = {};
   if (params.page != null) query.page = params.page;
   if (params.size != null) query.size = params.size;
+  if (params.release != null && params.release.trim().length > 0) {
+    query.release = params.release.trim();
+  }
   const { data } = await api.get<ReleaseListResponse>(
     `/v1/projects/${projectId}/releases`,
     { params: query },
diff --git a/apps/frontend/tests/unit/features/projects/releasesApi.test.ts b/apps/frontend/tests/unit/features/projects/releasesApi.test.ts
index f296b04..5eab08b 100644
--- a/apps/frontend/tests/unit/features/projects/releasesApi.test.ts
+++ b/apps/frontend/tests/unit/features/projects/releasesApi.test.ts
@@ -68,6 +68,19 @@ describe("releasesApi", () => {
       expect.objectContaining({ params: { page: 3, size: 25 } }),
     );
   });
+
+  it("forwards the version-label filter, trimmed", async () => {
+    await listProjectReleases("proj-1", { release: "  4.0  " });
+    const call = mockedGet.mock.calls.at(-1)!;
+    expect(call[1].params).toEqual({ release: "4.0" });
+  });
+
+  it("omits an absent or blank label so the list stays unfiltered", async () => {
+    await listProjectReleases("proj-1", { release: "   " });
+    expect(mockedGet.mock.calls.at(-1)![1].params).not.toHaveProperty("release");
+    await listProjectReleases("proj-1", {});
+    expect(mockedGet.mock.calls.at(-1)![1].params).not.toHaveProperty("release");
+  });
 });
 
 describe("releaseLabel", () => {
diff --git a/docs-site/docs/user-guide/projects.md b/docs-site/docs/user-guide/projects.md
index ad1aec3..d4086d1 100644
--- a/docs-site/docs/user-guide/projects.md
+++ b/docs-site/docs/user-guide/projects.md
@@ -236,6 +236,12 @@ Click a release row directly to navigate to the **Components** tab with the snap
 
 Downloads follow the pin too. With a release pinned, the **NOTICE** you download is composed from that release's licenses, not from the newest scan — so the attribution document you shipped with an earlier release stays retrievable after later scans succeed. Over the API this is `GET /v1/projects/{id}/notice?scan_id=<id>`; as with every other snapshot-anchored read, an id that is not one of this project's succeeded scans returns `404`.
 
+### Looking a version up by name
+
+Over the API, `GET /v1/projects/{id}/releases?release=4.0` returns the snapshot carrying that version label. Because a labelled scan supersedes any earlier scan claiming the same label, the answer is at most one row — read its `scan_id` and pin it on the detail endpoints (`?scan_id=`) to read that release's components, licences, findings, SBOM, or NOTICE. An unknown label returns an empty list rather than a `404`: not having shipped 9.9 yet is a normal answer, and a `404` would be indistinguishable from "no such project".
+
+The match is exact, not a search — `4.0` does not find `4.0.1`. Surrounding whitespace is trimmed on both sides.
+
 The companion **Compare** screen (the **Compare** button on the Releases-tab toolbar, enabled once the project has at least two releases) takes two snapshot ids — a **base** and a **target** — and shows what changed between them: added / removed / version-changed components, introduced / resolved vulnerabilities, and the risk-score, per-severity, license-tier, and build-gate deltas. A **swap** control flips base and target. The button defaults to comparing the newest release (target) against the one before it (base), and the two ids live in the URL (`?base=&target=`) so a specific comparison can be shared. It is the canonical diff view for "what changed between release X and release Y".
 
 ## The Reports tab {#the-reports-tab}
diff --git a/docs-site/i18n/ko/docusaurus-plugin-content-docs/current/user-guide/projects.md b/docs-site/i18n/ko/docusaurus-plugin-content-docs/current/user-guide/projects.md
index 54ed76c..480f53f 100644
--- a/docs-site/i18n/ko/docusaurus-plugin-content-docs/current/user-guide/projects.md
+++ b/docs-site/i18n/ko/docusaurus-plugin-content-docs/current/user-guide/projects.md
@@ -235,6 +235,12 @@ Overview 탭의 리스크 게이지 옆에는 **Project info** 카드가 있습
 
 다운로드도 핀을 따릅니다. 릴리스를 핀한 상태에서 **NOTICE**를 내려받으면 최신 스캔이 아니라 그 릴리스의 라이선스로 문서를 구성합니다. 이전 릴리스와 함께 출하한 고지 파일을 이후 스캔이 성공한 뒤에도 그대로 받을 수 있다는 뜻입니다. API로는 `GET /v1/projects/{id}/notice?scan_id=<id>`이며, 스냅샷을 앵커로 삼는 다른 조회와 마찬가지로 이 프로젝트의 성공한 스캔이 아닌 id를 주면 `404`를 반환합니다.
 
+### 버전 이름으로 찾기
+
+API에서는 `GET /v1/projects/{id}/releases?release=4.0`이 그 버전 라벨을 단 스냅샷을 돌려줍니다. 라벨이 붙은 스캔은 같은 라벨을 쓰던 이전 스캔을 밀어내므로 답은 많아야 한 행입니다. 그 행의 `scan_id`를 읽어 상세 엔드포인트에 `?scan_id=`로 고정하면 해당 릴리스의 컴포넌트·라이선스·취약점·SBOM·NOTICE를 읽을 수 있습니다. 없는 라벨은 `404`가 아니라 빈 목록을 돌려줍니다. 아직 9.9를 출시하지 않은 것은 정상적인 답이고, `404`로 답하면 "그런 프로젝트가 없다"와 구분되지 않기 때문입니다.
+
+검색이 아니라 정확히 일치하는 값을 찾습니다. `4.0`으로는 `4.0.1`을 찾지 못합니다. 앞뒤 공백은 양쪽 모두 제거하고 비교합니다.
+
 Releases 탭 툴바의 **Compare** 버튼(릴리스가 둘 이상일 때 활성화)으로 진입하는 **Compare** 화면은 두 스냅샷 id — **base**와 **target** — 를 받아 그 사이에 무엇이 변했는지 보여줍니다: 추가·제거·버전 변경된 컴포넌트, 새로 발생·해소된 취약점, 그리고 리스크 점수·severity별·라이선스 티어·빌드 게이트 델타. **swap** 컨트롤로 base와 target을 뒤바꿉니다. 버튼은 최신 릴리스(target)를 그 직전 릴리스(base)와 비교하도록 기본 설정되며, 두 id는 URL(`?base=&target=`)에 담겨 특정 비교를 공유할 수 있습니다. "릴리스 X와 Y 사이에 무엇이 변했는가"의 정식 diff 뷰입니다.
 
 ## Reports 탭 {#reports-탭}