diff --git a/backend/app/api/allowlist.py b/backend/app/api/allowlist.py
index 53f38bb..31241de 100644
--- a/backend/app/api/allowlist.py
+++ b/backend/app/api/allowlist.py
@@ -20,12 +20,37 @@ async def list_allowlist():
                 "tag_name": r.tag_name,
                 "tag_kind": r.tag_kind,
                 "min_confidence": r.min_confidence,
+                "applied_count": r.applied_count,
+                "coverage_count": r.coverage_count,
             }
             for r in rows
         ]
     )
 
 
+@allowlist_bp.route("/tags/<int:tag_id>/allowlist/coverage", methods=["GET"])
+async def coverage(tag_id: int):
+    """Live "at threshold T, a sweep would cover ~N images" projection for the
+    allowlist tuning dashboard. Defaults to the tag's stored threshold."""
+    raw = request.args.get("threshold")
+    async with get_session() as session:
+        svc = AllowlistService(session)
+        if raw is not None:
+            try:
+                threshold = float(raw)
+            except ValueError:
+                return jsonify({"error": "threshold must be a float"}), 400
+            if not (0 < threshold <= 1):
+                return jsonify({"error": "threshold must be in (0, 1]"}), 400
+        else:
+            row = await session.get(TagAllowlist, tag_id)
+            if row is None:
+                return jsonify({"error": "not on allowlist"}), 404
+            threshold = row.min_confidence
+        count = await svc.coverage(tag_id, threshold)
+    return jsonify({"count": count, "threshold": threshold})
+
+
 @allowlist_bp.route("/tags/<int:tag_id>/allowlist", methods=["GET"])
 async def get_one(tag_id: int):
     async with get_session() as session:
diff --git a/backend/app/api/suggestions.py b/backend/app/api/suggestions.py
index a8a9cf4..46fa2e5 100644
--- a/backend/app/api/suggestions.py
+++ b/backend/app/api/suggestions.py
@@ -3,12 +3,31 @@
 from quart import Blueprint, jsonify, request
 
 from ..extensions import get_session
+from ..models import Tag, TagAllowlist
 from ..services.ml.allowlist import AllowlistService
 from ..services.ml.suggestions import SuggestionService
 
 suggestions_bp = Blueprint("suggestions", __name__, url_prefix="/api")
 
 
+async def _accept_payload(session, svc, newly_added: bool, tag_id: int) -> dict:
+    """Shape the accept/alias response. When accepting newly allowlists a tag,
+    include the coverage PROJECTION (at the tag's threshold) so the UI can show
+    a non-blocking "auto-applying to ~N images" toast — the actual apply runs
+    async via apply_allowlist_tags, so this is an estimate, not a post-hoc
+    count (#7)."""
+    payload = {"allowlisted": newly_added}
+    if newly_added:
+        tag = await session.get(Tag, tag_id)
+        row = await session.get(TagAllowlist, tag_id)
+        payload["tag_id"] = tag_id
+        payload["tag_name"] = tag.name if tag is not None else None
+        payload["projected_count"] = await svc.coverage(
+            tag_id, row.min_confidence if row is not None else 0.90,
+        )
+    return payload
+
+
 @suggestions_bp.route("/images/<int:image_id>/suggestions", methods=["GET"])
 async def get_suggestions(image_id: int):
     # ?min=<float> overrides the configured per-category thresholds so the typed
@@ -60,13 +79,15 @@ async def accept_suggestion(image_id: int):
         return jsonify({"error": "tag_id required"}), 400
     tag_id = body["tag_id"]
     async with get_session() as session:
-        newly_added = await AllowlistService(session).accept(image_id, tag_id)
+        svc = AllowlistService(session)
+        newly_added = await svc.accept(image_id, tag_id)
+        payload = await _accept_payload(session, svc, newly_added, tag_id)
         await session.commit()
     if newly_added:
         from ..tasks.ml import apply_allowlist_tags
 
         apply_allowlist_tags.delay(tag_id=tag_id)
-    return "", 204
+    return jsonify(payload)
 
 
 @suggestions_bp.route(
@@ -77,19 +98,24 @@ async def alias_suggestion(image_id: int):
     required = {"alias_string", "alias_category", "canonical_tag_id"}
     if not body or not required.issubset(body):
         return jsonify({"error": f"required: {sorted(required)}"}), 400
+    canonical_tag_id = body["canonical_tag_id"]
     async with get_session() as session:
-        newly_added = await AllowlistService(session).add_alias_and_accept(
+        svc = AllowlistService(session)
+        newly_added = await svc.add_alias_and_accept(
             image_id,
             body["alias_string"],
             body["alias_category"],
-            body["canonical_tag_id"],
+            canonical_tag_id,
+        )
+        payload = await _accept_payload(
+            session, svc, newly_added, canonical_tag_id,
         )
         await session.commit()
     if newly_added:
         from ..tasks.ml import apply_allowlist_tags
 
-        apply_allowlist_tags.delay(tag_id=body["canonical_tag_id"])
-    return "", 204
+        apply_allowlist_tags.delay(tag_id=canonical_tag_id)
+    return jsonify(payload)
 
 
 @suggestions_bp.route(
diff --git a/backend/app/services/ml/allowlist.py b/backend/app/services/ml/allowlist.py
index 08a6ac7..8f7d14e 100644
--- a/backend/app/services/ml/allowlist.py
+++ b/backend/app/services/ml/allowlist.py
@@ -5,11 +5,18 @@ image_tag AND to tag_allowlist; per-image removal/dismiss writes a rejection.
 from collections.abc import Sequence
 from dataclasses import dataclass
 
-from sqlalchemy import delete, select
+from sqlalchemy import and_, delete, distinct, func, or_, select
 from sqlalchemy.dialects.postgresql import insert
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from ...models import MLSettings, Tag, TagAllowlist, TagSuggestionRejection
+from ...models import (
+    ImagePrediction,
+    MLSettings,
+    Tag,
+    TagAlias,
+    TagAllowlist,
+    TagSuggestionRejection,
+)
 from ...models.tag import image_tag
 from .aliases import AliasService
 
@@ -20,6 +27,8 @@ class AllowlistRow:
     tag_name: str
     tag_kind: str
     min_confidence: float
+    applied_count: int      # image_tag rows currently carrying this tag
+    coverage_count: int     # images a sweep WOULD cover at min_confidence
 
 
 class AllowlistService:
@@ -116,6 +125,44 @@ class AllowlistService:
             delete(TagAllowlist).where(TagAllowlist.tag_id == tag_id)
         )
 
+    async def _coverage_match(self, tag: Tag):
+        """The predicate over image_prediction rows that resolve to `tag`,
+        mirroring tasks.ml._confidence_for_tag's resolution: a prediction whose
+        raw_name equals the tag name (any category), OR an alias maps
+        (raw_name, category) -> this tag. Returns a SQLAlchemy boolean clause.
+        """
+        alias_rows = (
+            await self.session.execute(
+                select(TagAlias.alias_string, TagAlias.alias_category).where(
+                    TagAlias.canonical_tag_id == tag.id
+                )
+            )
+        ).all()
+        name_clause = ImagePrediction.raw_name == tag.name
+        alias_clauses = [
+            and_(
+                ImagePrediction.raw_name == a,
+                ImagePrediction.category == c,
+            )
+            for a, c in alias_rows
+        ]
+        return or_(name_clause, *alias_clauses) if alias_clauses else name_clause
+
+    async def coverage(self, tag_id: int, threshold: float) -> int:
+        """How many distinct images a sweep WOULD cover for this tag at
+        `threshold`: images with a resolving prediction scoring >= threshold.
+        The gross candidate pool (NOT minus already-applied/rejected) — it's
+        the tuning signal for "lower the threshold and ~N more images qualify".
+        """
+        tag = await self.session.get(Tag, tag_id)
+        if tag is None:
+            return 0
+        match = await self._coverage_match(tag)
+        stmt = select(
+            func.count(distinct(ImagePrediction.image_record_id))
+        ).where(ImagePrediction.score >= threshold, match)
+        return (await self.session.execute(stmt)).scalar_one()
+
     async def list_all(self) -> Sequence[AllowlistRow]:
         stmt = (
             select(
@@ -128,12 +175,33 @@ class AllowlistService:
             .order_by(Tag.name.asc())
         )
         rows = (await self.session.execute(stmt)).all()
-        return [
-            AllowlistRow(
-                tag_id=r[0],
-                tag_name=r[1],
-                tag_kind=r[2].value if hasattr(r[2], "value") else str(r[2]),
-                min_confidence=r[3],
+        tag_ids = [r[0] for r in rows]
+
+        # Applied counts in ONE grouped query (vs N per-row counts).
+        applied: dict[int, int] = {}
+        if tag_ids:
+            applied = dict(
+                (
+                    await self.session.execute(
+                        select(image_tag.c.tag_id, func.count())
+                        .where(image_tag.c.tag_id.in_(tag_ids))
+                        .group_by(image_tag.c.tag_id)
+                    )
+                ).all()
             )
-            for r in rows
-        ]
+
+        result = []
+        for r in rows:
+            # Coverage is per-tag (alias set differs); allowlist is small.
+            cov = await self.coverage(r[0], r[3])
+            result.append(
+                AllowlistRow(
+                    tag_id=r[0],
+                    tag_name=r[1],
+                    tag_kind=r[2].value if hasattr(r[2], "value") else str(r[2]),
+                    min_confidence=r[3],
+                    applied_count=applied.get(r[0], 0),
+                    coverage_count=cov,
+                )
+            )
+        return result
diff --git a/tests/test_api_allowlist.py b/tests/test_api_allowlist.py
index 3b4f45b..01539ae 100644
--- a/tests/test_api_allowlist.py
+++ b/tests/test_api_allowlist.py
@@ -1,6 +1,6 @@
 import pytest
 
-from backend.app.models import TagAllowlist, TagKind
+from backend.app.models import ImagePrediction, ImageRecord, TagAllowlist, TagKind
 from backend.app.services.tag_service import TagService
 
 pytestmark = pytest.mark.integration
@@ -39,3 +39,50 @@ async def test_patch_rejects_out_of_range(client, db):
         f"/api/tags/{tag.id}/allowlist", json={"min_confidence": 1.5}
     )
     assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_coverage_endpoint(client, db):
+    tag = await TagService(db).find_or_create("Cover", TagKind.general)
+    db.add(TagAllowlist(tag_id=tag.id, min_confidence=0.90))
+    for i, score in enumerate((0.95, 0.60)):
+        img = ImageRecord(
+            path=f"/images/cov{i}.jpg", sha256=f"cv{i:062d}", size_bytes=1,
+            mime="image/jpeg", width=1, height=1,
+            origin="imported_filesystem", integrity_status="unknown",
+        )
+        db.add(img)
+        await db.flush()
+        db.add(ImagePrediction(
+            image_record_id=img.id, raw_name="Cover",
+            category="general", score=score,
+        ))
+    await db.commit()
+
+    # Explicit threshold.
+    resp = await client.get(
+        f"/api/tags/{tag.id}/allowlist/coverage?threshold=0.90"
+    )
+    assert resp.status_code == 200
+    assert (await resp.get_json())["count"] == 1
+    # Lower what-if threshold widens coverage.
+    resp = await client.get(
+        f"/api/tags/{tag.id}/allowlist/coverage?threshold=0.50"
+    )
+    assert (await resp.get_json())["count"] == 2
+    # No threshold → uses the stored min_confidence (0.90).
+    resp = await client.get(f"/api/tags/{tag.id}/allowlist/coverage")
+    body = await resp.get_json()
+    assert body["count"] == 1
+    assert body["threshold"] == pytest.approx(0.90)
+
+
+@pytest.mark.asyncio
+async def test_coverage_rejects_bad_threshold(client, db):
+    tag = await TagService(db).find_or_create("Cover2", TagKind.general)
+    db.add(TagAllowlist(tag_id=tag.id))
+    await db.commit()
+    resp = await client.get(
+        f"/api/tags/{tag.id}/allowlist/coverage?threshold=2.0"
+    )
+    assert resp.status_code == 400
diff --git a/tests/test_api_suggestions.py b/tests/test_api_suggestions.py
index 84b95b0..36c0f89 100644
--- a/tests/test_api_suggestions.py
+++ b/tests/test_api_suggestions.py
@@ -14,11 +14,11 @@ def eager():
     celery.conf.task_always_eager = False
 
 
-async def _img(db, preds):
+async def _img(db, preds, sha="s" * 64):
     from tests._prediction_helpers import seed_predictions
 
     img = ImageRecord(
-        path="/images/s.jpg", sha256="s" * 64, size_bytes=1,
+        path=f"/images/{sha[:8]}.jpg", sha256=sha, size_bytes=1,
         mime="image/jpeg", width=1, height=1,
         origin="imported_filesystem", integrity_status="unknown",
     )
@@ -57,7 +57,31 @@ async def test_accept_then_applied(client, db):
     resp = await client.post(
         f"/api/images/{img.id}/suggestions/accept", json={"tag_id": tag.id}
     )
-    assert resp.status_code == 204
+    assert resp.status_code == 200
+    body = await resp.get_json()
+    # #7b: a fresh accept newly-allowlists → projection payload for the toast.
+    assert body["allowlisted"] is True
+    assert body["tag_id"] == tag.id
+    assert body["tag_name"] == "AcceptMe"
+    assert "projected_count" in body
+
+
+@pytest.mark.asyncio
+async def test_accept_already_allowlisted_reports_not_new(client, db):
+    img1 = await _img(db, {}, sha="c" * 64)
+    img2 = await _img(db, {}, sha="d" * 64)
+    tag = await TagService(db).find_or_create("Twice", TagKind.character)
+    await db.commit()
+    first = await client.post(
+        f"/api/images/{img1.id}/suggestions/accept", json={"tag_id": tag.id}
+    )
+    assert (await first.get_json())["allowlisted"] is True
+    second = await client.post(
+        f"/api/images/{img2.id}/suggestions/accept", json={"tag_id": tag.id}
+    )
+    body = await second.get_json()
+    assert body["allowlisted"] is False   # already on the allowlist
+    assert "projected_count" not in body
 
 
 @pytest.mark.asyncio
@@ -127,7 +151,8 @@ async def test_alias_roundtrip_resolves_by_raw_key(client, db):
             "canonical_tag_id": canonical.id,
         },
     )
-    assert resp.status_code == 204
+    assert resp.status_code == 200
+    assert (await resp.get_json())["allowlisted"] is True
 
     # (b) A DIFFERENT image with the same prediction now resolves via the alias
     # (image A's tag is applied, so it's filtered there). Had the alias been
diff --git a/tests/test_ml_allowlist.py b/tests/test_ml_allowlist.py
index ad3298f..3d853b1 100644
--- a/tests/test_ml_allowlist.py
+++ b/tests/test_ml_allowlist.py
@@ -1,7 +1,13 @@
 import pytest
 from sqlalchemy import select
 
-from backend.app.models import TagAllowlist, TagKind, TagSuggestionRejection
+from backend.app.models import (
+    ImagePrediction,
+    TagAlias,
+    TagAllowlist,
+    TagKind,
+    TagSuggestionRejection,
+)
 from backend.app.models.tag import image_tag
 from backend.app.services.ml.allowlist import AllowlistService
 from backend.app.services.tag_service import TagService
@@ -9,10 +15,10 @@ from backend.app.services.tag_service import TagService
 pytestmark = pytest.mark.integration
 
 
-async def _make_image(db):
+async def _make_image(db, sha: str = "x" * 64):
     from backend.app.models import ImageRecord
     img = ImageRecord(
-        path="/images/x.jpg", sha256="x" * 64, size_bytes=1,
+        path=f"/images/{sha[:8]}.jpg", sha256=sha, size_bytes=1,
         mime="image/jpeg", width=1, height=1,
         origin="imported_filesystem", integrity_status="unknown",
     )
@@ -21,6 +27,14 @@ async def _make_image(db):
     return img
 
 
+async def _add_pred(db, image_id, raw_name, score, category="general"):
+    db.add(ImagePrediction(
+        image_record_id=image_id, raw_name=raw_name,
+        category=category, score=score,
+    ))
+    await db.flush()
+
+
 @pytest.mark.asyncio
 async def test_accept_applies_and_allowlists(db):
     img = await _make_image(db)
@@ -106,6 +120,52 @@ async def test_update_threshold_and_remove(db):
     assert await db.get(TagAllowlist, tag.id) is None
 
 
+@pytest.mark.asyncio
+async def test_coverage_by_threshold_direct_name(db):
+    tag = await TagService(db).find_or_create("Cov", TagKind.general)
+    svc = AllowlistService(db)
+    for i, score in enumerate((0.95, 0.80, 0.60)):
+        img = await _make_image(db, sha=f"c{i:063d}")
+        await _add_pred(db, img.id, "Cov", score)
+    assert await svc.coverage(tag.id, 0.90) == 1
+    assert await svc.coverage(tag.id, 0.70) == 2
+    assert await svc.coverage(tag.id, 0.50) == 3
+
+
+@pytest.mark.asyncio
+async def test_coverage_via_alias_respects_category(db):
+    tag = await TagService(db).find_or_create("Aliased", TagKind.character)
+    db.add(TagAlias(
+        alias_string="model_key", alias_category="character",
+        canonical_tag_id=tag.id,
+    ))
+    await db.flush()
+    svc = AllowlistService(db)
+    hit = await _make_image(db, sha=f"a{0:063d}")
+    await _add_pred(db, hit.id, "model_key", 0.92, category="character")
+    # Same alias string but wrong category must NOT resolve to the tag.
+    miss = await _make_image(db, sha=f"a{1:063d}")
+    await _add_pred(db, miss.id, "model_key", 0.99, category="general")
+    assert await svc.coverage(tag.id, 0.90) == 1
+
+
+@pytest.mark.asyncio
+async def test_list_all_reports_applied_and_coverage(db):
+    tag = await TagService(db).find_or_create("Both", TagKind.general)
+    svc = AllowlistService(db)
+    applied_img = await _make_image(db, sha=f"b{0:063d}")
+    await svc.accept(applied_img.id, tag.id)  # applies + allowlists
+    await _add_pred(db, applied_img.id, "Both", 0.95)
+    # A second image only has a qualifying prediction (covered, not applied).
+    cov_img = await _make_image(db, sha=f"b{1:063d}")
+    await _add_pred(db, cov_img.id, "Both", 0.95)
+
+    rows = await svc.list_all()
+    row = next(r for r in rows if r.tag_id == tag.id)
+    assert row.applied_count == 1                 # only the accepted image
+    assert row.coverage_count == 2                # both have a ≥threshold pred
+
+
 @pytest.mark.asyncio
 async def test_update_threshold_clamped_to_store_floor(db):
     # A min_confidence below the store floor (default 0.70) is clamped up —