feat(provenance): gallery store post_id filter (mutually exclusive with tag_id)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/test/gallery.spec.js

@@ -0,0 +1,52 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
+import { setActivePinia, createPinia } from 'pinia'
+import { useGalleryStore } from '../src/stores/gallery.js'
+
+function stubFetch(handler) {
+  globalThis.fetch = vi.fn(async (url, init) => {
+    const { status, body } = handler(url, init)
+    return {
+      ok: status >= 200 && status < 300,
+      status,
+      statusText: String(status),
+      text: async () => (body == null ? '' : JSON.stringify(body))
+    }
+  })
+}
+
+const EMPTY = { images: [], date_groups: [], next_cursor: null }
+
+describe('gallery store: tag/post filter exclusivity', () => {
+  beforeEach(() => setActivePinia(createPinia()))
+  afterEach(() => vi.restoreAllMocks())
+
+  it('setPostFilter sets post_id and clears tag_id', () => {
+    const s = useGalleryStore()
+    stubFetch(() => ({ status: 200, body: EMPTY }))
+    s.setTagFilter(3)
+    expect(s.filter.tag_id).toBe(3)
+    s.setPostFilter(7)
+    expect(s.filter.post_id).toBe(7)
+    expect(s.filter.tag_id).toBe(null)
+  })
+
+  it('setTagFilter clears post_id', () => {
+    const s = useGalleryStore()
+    stubFetch(() => ({ status: 200, body: EMPTY }))
+    s.setPostFilter(7)
+    s.setTagFilter(3)
+    expect(s.filter.tag_id).toBe(3)
+    expect(s.filter.post_id).toBe(null)
+  })
+
+  it('loadMore sends exactly the active filter param', async () => {
+    const s = useGalleryStore()
+    const urls = []
+    stubFetch((url) => { urls.push(url); return { status: 200, body: EMPTY } })
+    s.setPostFilter(7)
+    await s.loadMore()
+    const scrollCall = urls.filter(u => u.includes('/api/gallery/scroll')).pop()
+    expect(scrollCall).toContain('post_id=7')
+    expect(scrollCall).not.toContain('tag_id=')
+  })
+})