diff --git a/.env.example b/.env.example
index 381284f..d50e257 100644
--- a/.env.example
+++ b/.env.example
@@ -41,7 +41,6 @@ JWT_REFRESH_TTL=720h
 
 # Server
 HTTP_ADDR=:8080
-APP_BASE_URL=http://localhost:8080
 
 # SSE
 SSE_HEARTBEAT_INTERVAL=25s
diff --git a/README.md b/README.md
index 603b8ff..6908c62 100644
--- a/README.md
+++ b/README.md
@@ -39,7 +39,6 @@ cp .env.example .env
 | Переменная | Значение по умолчанию | Описание |
 | --- | --- | --- |
 | `HTTP_ADDR` | `:8080` | Адрес прослушивания HTTP-сервера |
-| `APP_BASE_URL` | `http://localhost:8080` | Внешний базовый URL приложения (для ссылок и SSE) |
 | **База данных (метаданные)** | | |
 | `DB_BACKEND` | `sqlite` | Слой метаданных: `sqlite` или `postgres` |
 | `SQLITE_PATH` | `./galo.db` | Путь к файлу SQLite (при `DB_BACKEND=sqlite`) |
diff --git a/backend/internal/app/health_test.go b/backend/internal/app/health_test.go
index b6b733f..04ff7f5 100644
--- a/backend/internal/app/health_test.go
+++ b/backend/internal/app/health_test.go
@@ -18,7 +18,7 @@ import (
 
 func mustSigner(t *testing.T) *storage.Signer {
 	t.Helper()
-	signer, err := storage.NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	signer, err := storage.NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("signer: %v", err)
 	}
diff --git a/backend/internal/app/objects_test.go b/backend/internal/app/objects_test.go
index a0fee96..566125e 100644
--- a/backend/internal/app/objects_test.go
+++ b/backend/internal/app/objects_test.go
@@ -22,7 +22,7 @@ import (
 func newTestServerWithFS(t *testing.T) (*storage.FS, *gin.Engine) {
 	t.Helper()
 	gin.SetMode(gin.TestMode)
-	signer, err := storage.NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	signer, err := storage.NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("signer: %v", err)
 	}
diff --git a/backend/internal/app/share_flow_test.go b/backend/internal/app/share_flow_test.go
index ef7592b..f8cb0b8 100644
--- a/backend/internal/app/share_flow_test.go
+++ b/backend/internal/app/share_flow_test.go
@@ -149,7 +149,7 @@ func runShareFlow(t *testing.T, backend storage.Backend, verify func(t *testing.
 }
 
 func TestShareFlowWithFS(t *testing.T) {
-	signer, err := storage.NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	signer, err := storage.NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("signer: %v", err)
 	}
@@ -178,7 +178,7 @@ func TestShareFlowWithS3(t *testing.T) {
 	if endpoint == "" {
 		t.Skip("S3_ENDPOINT not set")
 	}
-	signer, err := storage.NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	signer, err := storage.NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Skipf("signer init: %v", err)
 	}
diff --git a/backend/internal/config/config.go b/backend/internal/config/config.go
index af8d90a..bd868fe 100644
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -39,8 +39,7 @@ type Auth struct {
 }
 
 type Server struct {
-	Addr    string
-	BaseURL string
+	Addr string
 }
 
 type SSE struct {
@@ -227,8 +226,7 @@ func Load() (*Config, error) {
 			RefreshTTL: refreshTTL,
 		},
 		Server: Server{
-			Addr:    getEnv("HTTP_ADDR", ":8080"),
-			BaseURL: getEnv("APP_BASE_URL", "http://localhost:8080"),
+			Addr: getEnv("HTTP_ADDR", ":8080"),
 		},
 		SSE: SSE{
 			HeartbeatInterval: heartbeat,
diff --git a/backend/internal/e2e/sqlite_test.go b/backend/internal/e2e/sqlite_test.go
index 95bf5ff..feed2f8 100644
--- a/backend/internal/e2e/sqlite_test.go
+++ b/backend/internal/e2e/sqlite_test.go
@@ -65,7 +65,7 @@ func openStack(t *testing.T, path, blobRoot string) (*stack, func()) {
 	}
 	repos := store.NewSQLite(database)
 	hub := sse.NewHub(1)
-	signer, err := storage.NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	signer, err := storage.NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("signer: %v", err)
 	}
diff --git a/backend/internal/photos/helpers_test.go b/backend/internal/photos/helpers_test.go
index 6209e53..bbfb646 100644
--- a/backend/internal/photos/helpers_test.go
+++ b/backend/internal/photos/helpers_test.go
@@ -106,7 +106,7 @@ func newTestService(t *testing.T, pool *pgxpool.Pool) (*Service, storage.Backend
 	if endpoint == "" {
 		t.Skip("S3_ENDPOINT not set")
 	}
-	signer, err := storage.NewSigner("http://app.test", "test-secret", time.Hour, 10*time.Minute)
+	signer, err := storage.NewSigner("test-secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Skipf("signer init: %v", err)
 	}
@@ -128,7 +128,7 @@ func newTestService(t *testing.T, pool *pgxpool.Pool) (*Service, storage.Backend
 // storage backend so the full flow can run without external infrastructure.
 func newTestServiceFS(t *testing.T, pool *pgxpool.Pool) (*Service, storage.Backend) {
 	t.Helper()
-	signer, err := storage.NewSigner("http://app.test", "test-secret", time.Hour, 10*time.Minute)
+	signer, err := storage.NewSigner("test-secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("storage init: %v", err)
 	}
diff --git a/backend/internal/storage/fs_test.go b/backend/internal/storage/fs_test.go
index b75777b..0cb9af4 100644
--- a/backend/internal/storage/fs_test.go
+++ b/backend/internal/storage/fs_test.go
@@ -16,7 +16,7 @@ import (
 
 func newTestFS(t *testing.T) *FS {
 	t.Helper()
-	signer, err := NewSigner("http://app.test", "test-secret", time.Hour, 10*time.Minute)
+	signer, err := NewSigner("test-secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("signer: %v", err)
 	}
diff --git a/backend/internal/storage/s3_test.go b/backend/internal/storage/s3_test.go
index 0b3ec65..36fa360 100644
--- a/backend/internal/storage/s3_test.go
+++ b/backend/internal/storage/s3_test.go
@@ -22,7 +22,7 @@ func newTestS3(t *testing.T) (*S3, *Signer) {
 	if endpoint == "" {
 		t.Skip("S3_ENDPOINT not set")
 	}
-	signer, err := NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	signer, err := NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("signer: %v", err)
 	}
diff --git a/backend/internal/storage/signer.go b/backend/internal/storage/signer.go
index 297c024..4ec4524 100644
--- a/backend/internal/storage/signer.go
+++ b/backend/internal/storage/signer.go
@@ -17,19 +17,18 @@ import (
 // route. It is shared by every storage backend so delivery is identical: the
 // client always talks to the backend, never to object storage directly.
 type Signer struct {
-	secret  []byte
-	baseURL string
-	ttl     time.Duration
-	window  time.Duration
-	now     func() time.Time
+	secret []byte
+	ttl    time.Duration
+	window time.Duration
+	now    func() time.Time
 }
 
-// NewSigner builds a signer. secret signs the URLs (required); baseURL is the
-// public base URL of the app; ttl limits URL lifetime (defaults to one hour);
-// window quantizes the expiry so the same object yields an identical URL within
-// one window (defaults to ten minutes, and is capped at ttl). A non-positive
-// window keeps the URL stable for its whole lifetime.
-func NewSigner(baseURL, secret string, ttl, window time.Duration) (*Signer, error) {
+// NewSigner builds a signer. secret signs the URLs (required); ttl limits URL
+// lifetime (defaults to one hour); window quantizes the expiry so the same
+// object yields an identical URL within one window (defaults to ten minutes, and
+// is capped at ttl). A non-positive window keeps the URL stable for its whole
+// lifetime.
+func NewSigner(secret string, ttl, window time.Duration) (*Signer, error) {
 	if strings.TrimSpace(secret) == "" {
 		return nil, errors.New("url secret is required")
 	}
@@ -43,23 +42,24 @@ func NewSigner(baseURL, secret string, ttl, window time.Duration) (*Signer, erro
 		window = ttl
 	}
 	return &Signer{
-		secret:  []byte(secret),
-		baseURL: strings.TrimRight(baseURL, "/"),
-		ttl:     ttl,
-		window:  window,
-		now:     time.Now,
+		secret: []byte(secret),
+		ttl:    ttl,
+		window: window,
+		now:    time.Now,
 	}, nil
 }
 
-// URL returns a signed app URL for the given opaque key. The expiry is
-// quantized to the signing window so repeated calls within that window return
-// the identical URL, letting clients reuse cached objects.
+// URL returns a signed object URL for the given opaque key. The URL is
+// origin-relative (it has no scheme or host) so the client fetches the blob from
+// the same origin that served the app, regardless of the deployment host. The
+// expiry is quantized to the signing window so repeated calls within that window
+// return the identical URL, letting clients reuse cached objects.
 func (s *Signer) URL(key string) string {
 	exp := s.expiry()
 	q := url.Values{}
 	q.Set("e", strconv.FormatInt(exp, 10))
 	q.Set("s", s.sign(key, exp))
-	return fmt.Sprintf("%s/api/objects/%s?%s", s.baseURL, escapeKey(key), q.Encode())
+	return fmt.Sprintf("/api/objects/%s?%s", escapeKey(key), q.Encode())
 }
 
 // expiry is the quantized Unix expiry shared by all URLs issued in the current
diff --git a/backend/internal/storage/signer_test.go b/backend/internal/storage/signer_test.go
index 5b432df..c89abe2 100644
--- a/backend/internal/storage/signer_test.go
+++ b/backend/internal/storage/signer_test.go
@@ -5,6 +5,7 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"strconv"
+	"strings"
 	"testing"
 	"time"
 )
@@ -23,7 +24,7 @@ func expiryOf(t *testing.T, raw string) int64 {
 }
 
 func TestSignerURLStableWithinWindow(t *testing.T) {
-	s, err := NewSigner("http://app.test", "secret", time.Hour, time.Hour)
+	s, err := NewSigner("secret", time.Hour, time.Hour)
 	if err != nil {
 		t.Fatalf("new signer: %v", err)
 	}
@@ -35,7 +36,7 @@ func TestSignerURLStableWithinWindow(t *testing.T) {
 }
 
 func TestSignerURLChangesAcrossWindow(t *testing.T) {
-	s, err := NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	s, err := NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("new signer: %v", err)
 	}
@@ -50,7 +51,7 @@ func TestSignerURLChangesAcrossWindow(t *testing.T) {
 }
 
 func TestSignerURLVerifies(t *testing.T) {
-	s, err := NewSigner("http://app.test", "secret", time.Hour, 10*time.Minute)
+	s, err := NewSigner("secret", time.Hour, 10*time.Minute)
 	if err != nil {
 		t.Fatalf("new signer: %v", err)
 	}
@@ -61,3 +62,21 @@ func TestSignerURLVerifies(t *testing.T) {
 		t.Fatalf("verify issued URL: %v", err)
 	}
 }
+
+func TestSignerURLIsOriginRelative(t *testing.T) {
+	s, err := NewSigner("secret", time.Hour, 10*time.Minute)
+	if err != nil {
+		t.Fatalf("new signer: %v", err)
+	}
+	raw := s.URL("objects/a/thumb.webp")
+	u, err := url.Parse(raw)
+	if err != nil {
+		t.Fatalf("parse url: %v", err)
+	}
+	if u.Scheme != "" || u.Host != "" || u.IsAbs() {
+		t.Fatalf("url is not origin-relative: %q", raw)
+	}
+	if !strings.HasPrefix(raw, "/api/objects/") {
+		t.Fatalf("url = %q, want /api/objects/ prefix", raw)
+	}
+}
diff --git a/backend/internal/storage/storage.go b/backend/internal/storage/storage.go
index f4277e3..ffa3fdf 100644
--- a/backend/internal/storage/storage.go
+++ b/backend/internal/storage/storage.go
@@ -111,7 +111,7 @@ func Open(ctx context.Context, cfg *config.Config, jwtSecret string) (Backend, e
 	if secret == "" {
 		return nil, errors.New("object URL secret is not available")
 	}
-	signer, err := NewSigner(cfg.Server.BaseURL, secret, cfg.Storage.URLTTL, cfg.Storage.URLSignWindow)
+	signer, err := NewSigner(secret, cfg.Storage.URLTTL, cfg.Storage.URLSignWindow)
 	if err != nil {
 		return nil, err
 	}
diff --git a/openspec/changes/host-agnostic-object-urls/.openspec.yaml b/openspec/changes/host-agnostic-object-urls/.openspec.yaml
new file mode 100644
index 0000000..a369219
--- /dev/null
+++ b/openspec/changes/host-agnostic-object-urls/.openspec.yaml
@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-10-11
diff --git a/openspec/changes/host-agnostic-object-urls/design.md b/openspec/changes/host-agnostic-object-urls/design.md
new file mode 100644
index 0000000..b37c4f0
--- /dev/null
+++ b/openspec/changes/host-agnostic-object-urls/design.md
@@ -0,0 +1,69 @@
+# Design
+
+## Context
+
+See `proposal.md` - Why. Relevant current state:
+
+- `storage.Signer.URL` builds `baseURL + "/api/objects/<key>?e&s"` (`signer.go`), with
+  `baseURL` from `cfg.Server.BaseURL` (`APP_BASE_URL`, default `http://localhost:8080`).
+- That absolute URL is the only use of `Server.BaseURL`; SSE and API traffic are already
+  root-relative (`/api/...`).
+- `photos.Service.attachURLs` runs outside an HTTP request, so it cannot see the request
+  host to derive a base.
+
+## Goals / Non-Goals
+
+**Goals:**
+- Photo/preview URLs work on any host or reverse proxy with no per-deployment base URL.
+- Preserve signing, expiry, quantization and caching behavior exactly.
+
+**Non-Goals:**
+- Serving the app under a URL subpath.
+- Absolute URL generation for non-browser consumers (no such consumer today).
+- Changing the object route, storage backends, or delivery semantics.
+
+## Decisions
+
+### Emit origin-relative (path-only) object URLs
+`Signer.URL(key)` returns `"/api/objects/<escaped-key>?e=<exp>&s=<sig>"`. A leading slash
+makes it origin-relative: the browser resolves it against the page's scheme/host/port,
+which is exactly the backend that served the page.
+
+- Alternative considered: keep absolute URLs and require operators to set
+  `APP_BASE_URL`. Rejected - this is the current footgun; a wrong or default value
+  silently breaks all images.
+- Alternative considered: derive the base from the request (`Host`,
+  `X-Forwarded-Proto`). Rejected - URLs are minted in `attachURLs`/SSE paths that have no
+  request; threading a base through every service is invasive for no benefit once URLs
+  are relative.
+- Alternative considered: document-relative URLs without a leading slash. Rejected - the
+  app and its API calls already use root-relative paths, so root-relative is consistent.
+
+### Remove the base URL from the signer and config
+Drop the `baseURL` field and parameter from `Signer`/`NewSigner`, stop reading
+`cfg.Server.BaseURL` in `storage.Open`, and remove `Server.BaseURL` from config,
+`.env.example` and the README. Leaving a now-unused variable would invite the same
+misconfiguration.
+
+### Verification unchanged
+`VerifyRequest` checks the key and query (`e`, `s`) only; it never used the host, so
+signing and validation are untouched.
+
+## Risks / Trade-offs
+
+- [Subpath deployment (`https://host/galo/`) would break with root-relative URLs] ->
+  The app already assumes root (`/api/...`); subpath support would be a separate change
+  adding a base-path prefix. Documented as out of scope.
+- [Non-browser clients need a base to resolve object URLs] -> None consume them today;
+  if one appears, it resolves against the instance base like any HTTP client.
+- [Tests that assumed an absolute URL] -> They parse the URL and use `Path`/`RawQuery`;
+  update `NewSigner` call sites to drop the base argument.
+
+## Migration Plan
+
+Remove `APP_BASE_URL` from the server environment and deploy the backend. No data or
+schema change. Rollback is reverting the deploy.
+
+## Open Questions
+
+None blocking.
diff --git a/openspec/changes/host-agnostic-object-urls/proposal.md b/openspec/changes/host-agnostic-object-urls/proposal.md
new file mode 100644
index 0000000..008193b
--- /dev/null
+++ b/openspec/changes/host-agnostic-object-urls/proposal.md
@@ -0,0 +1,41 @@
+# Proposal
+
+## Why
+
+Object URLs are absolute and built from `APP_BASE_URL`, whose default is
+`http://localhost:8080`. On a server reached by any other address the browser is told to
+fetch thumbnails and originals from `localhost`, so no photo or preview loads. This was
+observed on a deployment served from `http://192.168.77.82:8080/` with the default
+config: pages, login and album lists work (relative `/api/...`), but every image URL
+points at the client's own machine.
+
+## What Changes
+
+- Emit same-origin object URLs: the signer returns a path-only URL
+  (`/api/objects/<key>?e=...&s=...`) instead of an absolute one.
+- Remove the base URL from the signer (`Signer`/`NewSigner`) since it is no longer
+  needed; verification is unchanged (it uses the key and query only).
+- **BREAKING** (config): remove `APP_BASE_URL` / `Server.BaseURL`, which after this has
+  no remaining use (SSE and API calls are already relative). Update `.env.example` and
+  the README.
+
+## Capabilities
+
+### New Capabilities
+
+<!-- none -->
+
+### Modified Capabilities
+
+- `storage-backends`: add a requirement that issued object URLs are host-independent
+  (same-origin), so the app works behind any host or reverse proxy without calibrated
+  base-URL configuration.
+
+## Impact
+
+- Backend: `backend/internal/storage/signer.go`, `storage.go`
+  (`Open`/`NewSigner` call), `backend/internal/config/config.go` (`Server.BaseURL`).
+- Docs/config: `.env.example`, `README.md`.
+- Tests: signer/fs/objects/app/e2e call sites of `NewSigner` / `Server.BaseURL`.
+- Frontend: unchanged; relative URLs resolve against the page origin. The `sameOrigin`
+  helper in `PanoViewer` becomes a no-op but harmless.
diff --git a/openspec/changes/host-agnostic-object-urls/specs/storage-backends/spec.md b/openspec/changes/host-agnostic-object-urls/specs/storage-backends/spec.md
new file mode 100644
index 0000000..5dcd0a2
--- /dev/null
+++ b/openspec/changes/host-agnostic-object-urls/specs/storage-backends/spec.md
@@ -0,0 +1,20 @@
+# Spec Delta
+
+## ADDED Requirements
+
+### Requirement: Хост-независимые URL объектов
+Выдаваемый клиенту подписанный URL объекта SHALL быть относительным к текущему источнику
+(same-origin) и SHALL не содержать настроенный хост. Просмотр и скачивание медиа SHALL
+работать за любым хостом или обратным прокси без настройки внешнего базового URL.
+
+#### Scenario: Другой хост
+- **WHEN** приложение доступно по адресу, отличному от адреса по умолчанию, и клиент запрашивает фото
+- **THEN** URL объекта указывает на тот же источник, что и страница, и превью загружается без дополнительной настройки
+
+#### Scenario: Обратный прокси
+- **WHEN** приложение доступно за обратным прокси
+- **THEN** URL объектов сохраняют тот же источник, что и страница приложения
+
+#### Scenario: Подпись сохраняется
+- **WHEN** клиент получает относительный URL объекта
+- **THEN** подпись, срок действия и кэширование объекта работают как прежде
diff --git a/openspec/changes/host-agnostic-object-urls/tasks.md b/openspec/changes/host-agnostic-object-urls/tasks.md
new file mode 100644
index 0000000..d9c0b7d
--- /dev/null
+++ b/openspec/changes/host-agnostic-object-urls/tasks.md
@@ -0,0 +1,20 @@
+# Tasks
+
+## 1. Make object URLs origin-relative
+
+- [x] 1.1 In `backend/internal/storage/signer.go`, return a path-only URL (`/api/objects/<key>?e&s`) and drop the `baseURL` field/parameter from `Signer`/`NewSigner`; verify with `go test ./internal/storage/...`.
+- [x] 1.2 In `backend/internal/storage/storage.go`, stop passing `cfg.Server.BaseURL` to `NewSigner`; verify with `go build ./...`.
+
+## 2. Remove the base-URL configuration
+
+- [x] 2.1 Remove `Server.BaseURL` from `backend/internal/config/config.go` and delete the `APP_BASE_URL` line from `.env.example` and the README table; verify `go build ./...` and that no `APP_BASE_URL`/`Server.BaseURL` references remain.
+- [x] 2.2 Update every other `storage.NewSigner(...)` call site (tests/helpers in `internal/storage`, `internal/photos`, `internal/app`, `internal/e2e`) to drop the base argument; verify with `make test`.
+
+## 3. Integration verification
+
+- [x] 3.1 Run `make test` (backend) and `npm run build` (frontend); verify both pass and that an issued object URL has no scheme or host.
+
+## Workflow follow-up
+
+- Run `/opsx-apply` to implement this change.
+- Archive the change after review and verification (sync the delta spec into `storage-backends`).