diff --git a/backend/app/api/sources.py b/backend/app/api/sources.py
index 5b3fcaf..44227cb 100644
--- a/backend/app/api/sources.py
+++ b/backend/app/api/sources.py
@@ -136,6 +136,25 @@ async def delete_source(source_id: int):
     return "", 204
 
 
+@sources_bp.route("/<int:source_id>/reassign", methods=["POST"])
+async def reassign_source(source_id: int):
+    """Move this source (and the content it brought in) to another artist
+    (#130). Files don't move — the slug is immutable — so this just re-attributes
+    the source, its posts, and its images. Body: {target_artist_id}."""
+    body = await request.get_json(silent=True) or {}
+    target = body.get("target_artist_id")
+    if not isinstance(target, int):
+        return _bad("invalid_body", detail="target_artist_id (int) required")
+    async with get_session() as session:
+        try:
+            record = await SourceService(session).reassign(source_id, target)
+        except LookupError:
+            return _bad("not_found", status=404)
+        except ArtistNotFoundError:
+            return _bad("artist_not_found", detail="target artist not found", status=404)
+    return jsonify(record.to_dict())
+
+
 @sources_bp.route("/<int:source_id>/backfill", methods=["POST"])
 async def set_backfill(source_id: int):
     """Plan #693/#697 + #830: start/stop a backfill, or start a recovery /
diff --git a/backend/app/services/source_service.py b/backend/app/services/source_service.py
index 525cb1e..dcc66d5 100644
--- a/backend/app/services/source_service.py
+++ b/backend/app/services/source_service.py
@@ -4,11 +4,18 @@ is_subscription auto-flip on first add / last delete.
 
 from dataclasses import dataclass
 
-from sqlalchemy import func, select
+from sqlalchemy import func, select, update
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from ..models import Artist, ImportSettings, Source
+from ..models import (
+    Artist,
+    ImageProvenance,
+    ImageRecord,
+    ImportSettings,
+    Post,
+    Source,
+)
 from .platforms import known_platform_keys
 from .scheduler_service import compute_next_check_at
 
@@ -420,6 +427,70 @@ class SourceService:
         await self.session.commit()
         return await self._row_to_record(source)
 
+    async def reassign(self, source_id: int, target_artist_id: int) -> SourceRecord:
+        """Move a Source — and the content it brought in — to another artist
+        (#130). The slug/storage path is IMMUTABLE, so NO files move: only the
+        artist attribution changes (reads use ImageRecord.path). Re-points the
+        source's Posts and the ImageRecords it contributed (those still
+        attributed to the old artist — images shared with another artist are
+        left alone). If the old artist is left fully empty (no sources, images,
+        or posts) it's deleted (ArtistVisit cascades); if it just lost its last
+        source, its is_subscription flag clears. No-op when already on target."""
+        source = (await self.session.execute(
+            select(Source).where(Source.id == source_id)
+        )).scalar_one_or_none()
+        if source is None:
+            raise LookupError(f"source id={source_id} not found")
+        target = await self._artist_or_raise(target_artist_id)
+        old_artist_id = source.artist_id
+        if old_artist_id == target_artist_id:
+            return await self._row_to_record(source)
+
+        source.artist_id = target_artist_id
+        target.is_subscription = True
+        # Re-attribute this source's posts (Post.artist_id is denormalized).
+        await self.session.execute(
+            update(Post).where(Post.source_id == source_id)
+            .values(artist_id=target_artist_id)
+        )
+        # Re-attribute the images this source contributed that are still on the
+        # OLD artist. Scoping to artist_id == old avoids stealing an image that
+        # a different artist's source also contributed.
+        contributed = select(ImageProvenance.image_record_id).where(
+            ImageProvenance.source_id == source_id
+        )
+        await self.session.execute(
+            update(ImageRecord)
+            .where(
+                ImageRecord.artist_id == old_artist_id,
+                ImageRecord.id.in_(contributed),
+            )
+            .values(artist_id=target_artist_id)
+        )
+        await self.session.flush()
+
+        old = (await self.session.execute(
+            select(Artist).where(Artist.id == old_artist_id)
+        )).scalar_one_or_none()
+        if old is not None:
+            n_src = (await self.session.execute(
+                select(func.count(Source.id)).where(Source.artist_id == old_artist_id)
+            )).scalar_one()
+            n_img = (await self.session.execute(
+                select(func.count(ImageRecord.id)).where(
+                    ImageRecord.artist_id == old_artist_id
+                )
+            )).scalar_one()
+            n_post = (await self.session.execute(
+                select(func.count(Post.id)).where(Post.artist_id == old_artist_id)
+            )).scalar_one()
+            if n_src == 0 and n_img == 0 and n_post == 0:
+                await self.session.delete(old)      # ArtistVisit cascades
+            elif n_src == 0:
+                old.is_subscription = False
+        await self.session.commit()
+        return await self._row_to_record(source)
+
     async def delete(self, source_id: int) -> None:
         source = (await self.session.execute(
             select(Source).where(Source.id == source_id)
diff --git a/frontend/src/components/artist/ArtistManagementTab.vue b/frontend/src/components/artist/ArtistManagementTab.vue
index b78c2a1..c6ab511 100644
--- a/frontend/src/components/artist/ArtistManagementTab.vue
+++ b/frontend/src/components/artist/ArtistManagementTab.vue
@@ -47,18 +47,60 @@
       </div>
       <v-table density="compact">
         <thead>
-          <tr><th>Platform</th><th>URL</th><th class="text-right">Images</th></tr>
+          <tr>
+            <th>Platform</th><th>URL</th>
+            <th class="text-right">Images</th><th></th>
+          </tr>
         </thead>
         <tbody>
           <tr v-for="s in overview.sources" :key="s.id">
             <td>{{ s.platform }}</td>
             <td class="fc-artist-mgmt__url">{{ s.url }}</td>
             <td class="text-right">{{ s.image_count }}</td>
+            <td class="text-right">
+              <v-btn
+                size="x-small" variant="text" prepend-icon="mdi-account-arrow-right"
+                @click="openMove(s)"
+              >Move…</v-btn>
+            </td>
           </tr>
         </tbody>
       </v-table>
     </section>
 
+    <!-- #130: move a source into a different (existing) artist. The slug is
+         immutable so no files move — just re-attribution. -->
+    <v-dialog v-model="moveOpen" max-width="480">
+      <v-card>
+        <v-card-title class="fc-h2">Move source to another artist</v-card-title>
+        <v-card-text>
+          <p class="mb-3 text-body-2">
+            Moving <strong>{{ moveSource?.platform }}</strong> and the posts/images
+            it brought in to another artist. Files aren't moved — only the
+            attribution changes. If <strong>{{ overview.name }}</strong> is left
+            empty it will be removed.
+          </p>
+          <v-autocomplete
+            v-model="moveTarget"
+            :items="artistItems"
+            :loading="searching"
+            item-title="name" item-value="id" return-object
+            label="Target artist" density="compact" variant="outlined"
+            no-filter hide-details autofocus clearable
+            @update:search="onSearch"
+          />
+        </v-card-text>
+        <v-card-actions>
+          <v-spacer />
+          <v-btn variant="text" @click="moveOpen = false">Cancel</v-btn>
+          <v-btn
+            color="accent" :disabled="!moveTarget || moving" :loading="moving"
+            @click="confirmMove"
+          >Move</v-btn>
+        </v-card-actions>
+      </v-card>
+    </v-dialog>
+
     <section class="fc-artist-mgmt__sec">
       <h2 class="fc-h2">Danger zone</h2>
       <ArtistDangerZone
@@ -71,9 +113,11 @@
 </template>
 
 <script setup>
-import { computed } from 'vue'
+import { computed, ref } from 'vue'
 import { useRouter, RouterLink } from 'vue-router'
 
+import { useSourcesStore } from '../../stores/sources.js'
+import { toast } from '../../utils/toast.js'
 import ArtistDangerZone from './ArtistDangerZone.vue'
 
 const props = defineProps({
@@ -81,6 +125,53 @@ const props = defineProps({
 })
 
 const router = useRouter()
+const sources = useSourcesStore()
+
+// #130: move a source into another artist.
+const moveOpen = ref(false)
+const moveSource = ref(null)
+const moveTarget = ref(null)
+const artistItems = ref([])
+const searching = ref(false)
+const moving = ref(false)
+
+function openMove (s) {
+  moveSource.value = s
+  moveTarget.value = null
+  artistItems.value = []
+  moveOpen.value = true
+}
+
+let searchSeq = 0
+async function onSearch (q) {
+  const mine = ++searchSeq
+  if (!q || !q.trim()) { artistItems.value = []; return }
+  searching.value = true
+  try {
+    const rows = await sources.autocompleteArtist(q)
+    // Drop the current artist — you can't move a source onto itself.
+    if (mine === searchSeq) artistItems.value = rows.filter(a => a.id !== props.overview.id)
+  } finally {
+    if (mine === searchSeq) searching.value = false
+  }
+}
+
+async function confirmMove () {
+  if (!moveTarget.value || !moveSource.value) return
+  moving.value = true
+  try {
+    await sources.reassign(moveSource.value.id, moveTarget.value.id)
+    moveOpen.value = false
+    toast({ text: `Moved to ${moveTarget.value.name}`, type: 'success' })
+    // The current artist may now be empty (deleted); route to the target,
+    // whose slug is stable (immutable).
+    router.push({ name: 'artist', params: { slug: moveTarget.value.slug } })
+  } catch (e) {
+    toast({ text: `Move failed: ${e.message}`, type: 'error' })
+  } finally {
+    moving.value = false
+  }
+}
 
 const sparkW = 600
 const sparkH = 80
diff --git a/frontend/src/stores/sources.js b/frontend/src/stores/sources.js
index 10c16b5..d169873 100644
--- a/frontend/src/stores/sources.js
+++ b/frontend/src/stores/sources.js
@@ -84,6 +84,15 @@ export const useSourcesStore = defineStore('sources', () => {
     return await api.get('/api/artists/autocomplete', { params: { q: query, limit } })
   }
 
+  // #130: move a source (+ its content) to another artist. Files don't move
+  // (slug is immutable); the backend re-attributes source/posts/images and
+  // deletes the old artist if it's left empty.
+  async function reassign(id, targetArtistId) {
+    return await api.post(`/api/sources/${id}/reassign`, {
+      body: { target_artist_id: targetArtistId },
+    })
+  }
+
   async function loadScheduleStatus() {
     scheduleStatus.value = await api.get('/api/sources/schedule-status')
     return scheduleStatus.value
@@ -177,7 +186,7 @@ export const useSourcesStore = defineStore('sources', () => {
     recoverSource,
     recaptureSource,
     previewSource,
-    findOrCreateArtist, autocompleteArtist,
+    findOrCreateArtist, autocompleteArtist, reassign,
     loadScheduleStatus,
     sourcesByArtistGrouped,
   }
diff --git a/tests/test_source_service.py b/tests/test_source_service.py
index e9fc942..a9bdc28 100644
--- a/tests/test_source_service.py
+++ b/tests/test_source_service.py
@@ -186,6 +186,94 @@ async def test_update_while_enabled_keeps_failure_state(db):
     assert refetched.consecutive_failures == 3
 
 
+async def _source_with_content(db, svc, artist):
+    """A source under `artist` with one post + one image it contributed."""
+    from backend.app.models import ImageProvenance, ImageRecord, Post
+    rec = await svc.create(
+        artist_id=artist.id, platform="pixiv",
+        url=f"https://www.pixiv.net/users/{artist.id}",
+    )
+    post = Post(source_id=rec.id, artist_id=artist.id, external_post_id="p1")
+    db.add(post)
+    img = ImageRecord(
+        path=f"/images/{artist.slug}/pixiv/pixiv/1_a_00.jpg",
+        sha256=str(artist.id).rjust(64, "0"), size_bytes=1, mime="image/jpeg",
+        width=1, height=1, origin="imported_filesystem",
+        integrity_status="unknown", artist_id=artist.id,
+    )
+    db.add(img)
+    await db.flush()
+    db.add(ImageProvenance(image_record_id=img.id, post_id=post.id, source_id=rec.id))
+    await db.commit()
+    return rec, post, img
+
+
+@pytest.mark.asyncio
+async def test_reassign_moves_source_posts_images(db):
+    from backend.app.models import ImageRecord, Post
+    old = await _artist(db, "OldOwner")
+    new = await _artist(db, "NewOwner")
+    svc = SourceService(db)
+    rec, post, img = await _source_with_content(db, svc, old)
+
+    await svc.reassign(rec.id, new.id)
+
+    assert (await db.execute(
+        select(Source.artist_id).where(Source.id == rec.id)
+    )).scalar_one() == new.id
+    assert (await db.execute(
+        select(Post.artist_id).where(Post.id == post.id)
+    )).scalar_one() == new.id
+    assert (await db.execute(
+        select(ImageRecord.artist_id).where(ImageRecord.id == img.id)
+    )).scalar_one() == new.id
+    # Old artist is now empty → deleted.
+    assert (await db.execute(
+        select(Artist).where(Artist.id == old.id)
+    )).scalar_one_or_none() is None
+
+
+@pytest.mark.asyncio
+async def test_reassign_keeps_nonempty_old_artist(db):
+    from backend.app.models import ImageRecord
+    old = await _artist(db, "OldMulti")
+    new = await _artist(db, "NewMulti")
+    svc = SourceService(db)
+    rec, _post, _img = await _source_with_content(db, svc, old)
+    # A second, unrelated image keeps `old` non-empty after the move.
+    db.add(ImageRecord(
+        path="/images/oldmulti/loose.jpg", sha256="e" * 64, size_bytes=1,
+        mime="image/jpeg", width=1, height=1, origin="imported_filesystem",
+        integrity_status="unknown", artist_id=old.id,
+    ))
+    await db.commit()
+
+    await svc.reassign(rec.id, new.id)
+    still = (await db.execute(
+        select(Artist).where(Artist.id == old.id)
+    )).scalar_one()
+    assert still.is_subscription is False        # lost its last source
+
+
+@pytest.mark.asyncio
+async def test_reassign_same_artist_is_noop(db):
+    a = await _artist(db, "Solo")
+    svc = SourceService(db)
+    rec, _post, _img = await _source_with_content(db, svc, a)
+    out = await svc.reassign(rec.id, a.id)
+    assert out.artist_id == a.id
+
+
+@pytest.mark.asyncio
+async def test_reassign_unknown_target_raises(db):
+    from backend.app.services.source_service import ArtistNotFoundError
+    a = await _artist(db, "Whom")
+    svc = SourceService(db)
+    rec, _post, _img = await _source_with_content(db, svc, a)
+    with pytest.raises(ArtistNotFoundError):
+        await svc.reassign(rec.id, 999999)
+
+
 @pytest.mark.asyncio
 async def test_list_hides_sidecar_synthetic_anchors(db):
     """Filesystem-import synthetic Sources (url='sidecar:<platform>:<slug>',