diff --git a/api.py b/api.py
index d4f5193..345d894 100644
--- a/api.py
+++ b/api.py
@@ -187,11 +187,15 @@ async def _create_milestone(body: dict = Body(...)):
     # ── features ──────────────────────────────────────────────────────────────
     @router.get("/features")
     async def _features(state: str | None = None):
-        return {"features": store().list_features(state=state)}
+        # _guard, like every other store-touching route: an unusable board (no repo
+        # bound, no .beads, br missing) must reach the view as JSON 400 with the
+        # actionable BoardError message — an escaped BoardError is a text/plain 500
+        # the view can only render as a JSON-parse error.
+        return _guard(lambda: {"features": store().list_features(state=state)})
 
     @router.get("/features/{fid}")
     async def _feature(fid: str):
-        f = store().get_feature(fid)
+        f = _guard(lambda: store().get_feature(fid))
         if f is None:
             raise HTTPException(404, f"unknown feature {fid!r}")
         return f
diff --git a/board_view.py b/board_view.py
index 20bf75a..6788c97 100644
--- a/board_view.py
+++ b/board_view.py
@@ -102,7 +102,14 @@
   in_progress:"var(--pl-color-accent)", in_review:"var(--pl-color-status-info)",
   done:"var(--pl-color-fg-muted)", blocked:"var(--pl-color-status-error)"};
 // Slug-aware authed fetch via the kit (rules 2+3) — pass a bare /api/... path.
-const api = (p) => kit.apiFetch(p).then(r => r.json());
+// Errors become READABLE: a JSON error body surfaces its `detail` (the actionable
+// BoardError message), a non-JSON body its HTTP status — never a raw parse error.
+const api = async (p) => {
+  const r = await kit.apiFetch(p);
+  const d = await r.json().catch(() => { throw new Error("HTTP " + r.status + " (non-JSON response)"); });
+  if (!r.ok) throw new Error(d.detail || "HTTP " + r.status);
+  return d;
+};
 const $ = (id) => document.getElementById(id);
 const esc = (s) => (s||"").replace(/[&<>"]/g, c => ({"&":"&amp;","<":"&lt;",">":"&gt;",'"':"&quot;"}[c]));
 
diff --git a/tests/test_api.py b/tests/test_api.py
index 19a4774..0bcee67 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -136,6 +136,26 @@ def test_data_routes_live_on_the_gated_prefix(monkeypatch):
     assert c.get("/plugins/project_board/features").status_code == 404
 
 
+def test_unusable_board_reads_surface_as_json_400_not_500(monkeypatch):
+    """An unusable board (no repo bound, no .beads, br missing) raises BoardError
+    on ANY read — that must reach the view as JSON 400 carrying the actionable
+    message, not escape as a text/plain 500 the page can only show as a
+    JSON-parse error."""
+
+    class BrokenStore(FakeStore):
+        def list_features(self, state=None):
+            raise BoardError("repo '.' has no beads workspace — set project_board.repo")
+
+        def get_feature(self, fid):
+            raise BoardError("repo '.' has no beads workspace — set project_board.repo")
+
+    c = _client(monkeypatch, BrokenStore())
+    for path in ("/api/plugins/project_board/features", "/api/plugins/project_board/features/bd-1"):
+        r = c.get(path)
+        assert r.status_code == 400, path
+        assert "beads workspace" in r.json()["detail"], path
+
+
 # ── CRUD + the Ready gate surfacing as 400 ──────────────────────────────────────