fix(slice-17): default rail item filter

packages/daemon/src/domain/slices/slice-indexer.ts

@@ -435,11 +435,13 @@ export class SliceIndexer {
 
       // 2. Substring matches. Terms are chosen so the missionId term
       // is INCLUDED only when no typed-tag rows exist (legacy
-      // compatibility); otherwise the slice-specific terms (sliceName +
-      // railItem) drive matching. railItem stays in both branches
-      // because it's slice-scoped, not mission-scoped.
+      // compatibility); otherwise the slice-specific terms drive
+      // matching. In mission-folder workspaces, railItem defaults to
+      // missionId when no explicit rail item is authored, so the typed-tag
+      // branch must not blindly keep that fallback or mission-only qitems
+      // leak back into every slice in the mission.
       const substringTerms = (typedTagMatchCount > 0
-        ? [sliceName, railItem]
+        ? [sliceName, railItem === missionId ? null : railItem]
         : [sliceName, railItem, missionId]
       ).filter((v): v is string => !!v);
       for (const term of Array.from(new Set(substringTerms))) {

packages/daemon/test/slice-indexer.test.ts

@@ -325,6 +325,29 @@ describe("PL-slice-story-view-v0 SliceIndexer", () => {
       expect(slice.qitemIds).not.toContain("q-mission-tag-only");
     });
 
+    it("does not re-include mission-only qitems when railItem defaults to missionId", () => {
+      const missionsRoot = path.join(cleanup, "missions");
+      writeSlice(path.join(missionsRoot, "release-fake-default-rail", "slices"), "fake-slice-default-rail", {
+        "README.md": "---\nstatus: active\n---\n# Fake default rail\n",
+      });
+      insertQitem(db, {
+        qitemId: "q-default-rail-typed-slice-tag",
+        body: "Body without slice name.",
+        tags: ["slice:fake-slice-default-rail"],
+      });
+      insertQitem(db, {
+        qitemId: "q-default-rail-mission-tag-only",
+        body: "Body without slice name.",
+        tags: ["mission:release-fake-default-rail"],
+      });
+
+      const indexer = new SliceIndexer({ slicesRoot: missionsRoot, dogfoodEvidenceRoot: null, db });
+      const slice = indexer.get("fake-slice-default-rail")!;
+      expect(slice.railItem).toBe("release-fake-default-rail");
+      expect(slice.qitemIds).toEqual(["q-default-rail-typed-slice-tag"]);
+      expect(slice.qitemIds).not.toContain("q-default-rail-mission-tag-only");
+    });
+
     it("preserves legacy substring fallback (including mission body) when NO typed slice: tag exists", () => {
       // When no qitem has the typed `slice:<name>` tag, the indexer
       // falls back to the pre-fix three-term substring union so older