diff --git a/.changeset/app-only-slot-stamping.md b/.changeset/app-only-slot-stamping.md
new file mode 100644
index 00000000..c0758104
--- /dev/null
+++ b/.changeset/app-only-slot-stamping.md
@@ -0,0 +1,5 @@
+---
+"everything-dev": patch
+---
+
+Hotfix for the rc.26 slot-stamping incident: the deploy train now stamps only `app.*` slots (the base-runtime slots children never author — auth, host) from the release manifest's slots map. Plugin slots were being stamped into the child's leaf payload, which both expanded a declared-plugin child's composed plugin set to the whole parent set (violating the extends contract — a child's declared `plugins` object owns the entire plugin domain via a wholesale replace) and produced schema-invalid `plugins.<id>.ui` records (stamped ui entries carry no required `name`, and the wholesale replace never fills it) — blocking every child with authored plugins from deploying. Children pinned to rc.26 with authored `plugins` are CI-blocked until they run `bos upgrade`; live apps are unaffected (the boot-check refused the publish before any registry write).
diff --git a/packages/everything-dev/src/services/deploy/composition.ts b/packages/everything-dev/src/services/deploy/composition.ts
index 07ccfdee..cc428644 100644
--- a/packages/everything-dev/src/services/deploy/composition.ts
+++ b/packages/everything-dev/src/services/deploy/composition.ts
@@ -71,12 +71,12 @@ export interface StampOutcome {
 }
 
 /**
- * Stamp inherited slots: for every slot in the release manifest's `slots` map
- * that the authored config does not declare, write the release's recorded
- * production URL + pin into the payload. Child-wins deep merge then shadows
- * the parent's live config pointer at every consumer boot, so the child
- * composes exactly the bytes its pinned release published. Slots the child
- * authors stay untouched, and a manifest without `slots` (pre-amendment
+ * Stamp inherited slots: for every `app.*` slot in the release manifest's
+ * `slots` map that the authored config does not declare, write the release's
+ * recorded production URL + pin into the payload. Child-wins deep merge then
+ * shadows the parent's live config pointer at every consumer boot, so the
+ * child composes exactly the bytes its pinned release published. Slots the
+ * child authors stay untouched, and a manifest without `slots` (pre-amendment
  * releases) stamps nothing — the composition gate covers those children.
  */
 export function stampInheritedSlotsFromRelease(input: {
@@ -89,6 +89,14 @@ export function stampInheritedSlotsFromRelease(input: {
   const stamped: string[] = [];
 
   for (const [slotPath, record] of Object.entries(slots)) {
+    // KEEP: only app.* slots are stampable — a child's declared `plugins`
+    // object owns the whole plugin domain in one wholesale replace
+    // (mergeBosConfigWithExtends), so stamping parent plugin slots would
+    // both expand the child's composed plugin set and produce
+    // schema-invalid entries (the stamped ui record alone carries no
+    // required `name`; the wholesale replace never fills it — the
+    // feedback.nearbuilders.org rc.26 incident).
+    if (!/^app\.[^.]+(\.ui)?$/.test(slotPath)) continue;
     if (authored.has(slotPath)) continue;
     stampSlotRecord(input.payload, slotPath, record);
     stamped.push(slotPath);
diff --git a/packages/everything-dev/tests/integration/platform-upgrade-e2e.test.ts b/packages/everything-dev/tests/integration/platform-upgrade-e2e.test.ts
index 55a226e7..609acd42 100644
--- a/packages/everything-dev/tests/integration/platform-upgrade-e2e.test.ts
+++ b/packages/everything-dev/tests/integration/platform-upgrade-e2e.test.ts
@@ -39,7 +39,10 @@ import {
   PlatformReleaseManifestSchema,
   resolvePlatformManifest,
 } from "../../src/services/platform/manifest";
-import { resolveBootShape } from "../../src/services/resolution/boot-check";
+import {
+  resolveBootShape,
+  verifyResolvedBootShape,
+} from "../../src/services/resolution/boot-check";
 import { applyPlatformPin } from "../../src/services/scaffold/upgrade-migration";
 import {
   type ExtendedRootSourceOptions,
@@ -534,6 +537,7 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
     );
     const authPin = pinFor("/auth/", `versions/auth-${version}.json`, shared);
     const authUiPin = pinFor("/auth-ui/", `versions/auth-ui-${version}.json`, shared);
+    const parentUi = { production: `${base}/auth-ui/`, pin: authUiPin, name: "auth" };
     const entry = composePlatformManifestPublishEntry({
       configDir: rootDir,
       account: ACCOUNT,
@@ -544,7 +548,18 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
           auth: {
             production: `${base}/auth/`,
             pin: authPin,
-            ui: { production: `${base}/auth-ui/`, pin: authUiPin },
+            ui: parentUi,
+          },
+        },
+        plugins: {
+          votes: {
+            production: `${base}/votes/`,
+            pin: pinFor("/votes/", `versions/votes-${version}.json`, shared),
+            ui: {
+              production: `${base}/votes-ui/`,
+              pin: pinFor("/votes-ui/", `versions/votes-ui-${version}.json`, shared),
+              name: "votes-ui",
+            },
           },
         },
       },
@@ -556,10 +571,13 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
       account: ACCOUNT,
       domain: GATEWAY,
       app: {
+        host: { production: `${base}/host/` },
+        ui: { production: `${base}/ui/` },
+        api: { production: `${base}/api/` },
         auth: {
           production: `${base}/auth/`,
           pin: authPin,
-          ui: { production: `${base}/auth-ui/`, pin: authUiPin },
+          ui: parentUi,
         },
       },
     });
@@ -567,12 +585,19 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
   }
 
   /** The deploy train's payload assembly, compressed: authored config, the
-   * train-applied own-ui pin, optional stamps, one boot walk, then the gate. */
+   * train-applied own-ui pin, optional stamps, one boot walk, the boot-check
+   * schema parse of the merged shape, then the gate. */
   async function simulateDeploy(
     authoredConfig: Record<string, unknown>,
     ownUiPin: { manifest: string; integrity: string },
     stamps: boolean,
-  ): Promise<{ ok: boolean; violations: string[]; merged: Record<string, unknown> }> {
+  ): Promise<{
+    ok: boolean;
+    violations: string[];
+    merged: Record<string, unknown>;
+    stamped: string[];
+    bootOk: boolean;
+  }> {
     const resolvedRelease = await resolveReleaseManifestForDeploy({
       configDir: childDir,
       authoredConfig,
@@ -582,14 +607,16 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
     const app = payload.app as Record<string, Record<string, unknown>>;
     app.ui.production = `${base}/child-ui/`;
     app.ui.pin = ownUiPin;
+    let stamped: string[] = [];
     if (stamps && resolvedRelease?.slots) {
-      stampInheritedSlotsFromRelease({
+      stamped = stampInheritedSlotsFromRelease({
         payload,
         authoredConfig,
         manifest: resolvedRelease,
-      });
+      }).stamped;
     }
     const bootShape = await resolveBootShape(payload, CHILD_SLOT, { io: registryIo });
+    const bootCheck = verifyResolvedBootShape(payload, bootShape);
     const gate = await runCompositionGate({
       configDir: childDir,
       authoredConfig,
@@ -601,6 +628,8 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
       ok: gate.ok,
       violations: gate.violations,
       merged: bootShape.config as Record<string, unknown>,
+      stamped,
+      bootOk: bootCheck.ok,
     };
   }
 
@@ -655,8 +684,9 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
       domain: "child.example",
       platform: "2.0.0-rc.1",
       app: { ui: { development: "local:ui" } },
+      plugins: { feedback: { extends: `bos://${ACCOUNT}/${GATEWAY}/votes` } },
     };
-    const { ok, violations, merged } = await simulateDeploy(
+    const { ok, violations, merged, stamped, bootOk } = await simulateDeploy(
       authoredConfig,
       {
         manifest: "versions/fedcba0987654321.json",
@@ -664,11 +694,18 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
       },
       true,
     );
+    expect(bootOk).toBe(true);
     expect(violations).toEqual([]);
 
+    // the release records the parent's plugin slots too — the child's own
+    // declared plugin set owns that domain, so none of them stamp
+    expect(stamped).toEqual(["app.auth", "app.auth.ui"]);
     const app = merged.app as Record<string, Record<string, Record<string, string>>>;
     expect(app.auth.pin.manifest).toBe("versions/auth-2.0.0-rc.1.json");
     expect(app.auth.ui.pin.manifest).toBe("versions/auth-ui-2.0.0-rc.1.json");
+    expect(merged.plugins).toEqual({
+      feedback: { extends: `bos://${ACCOUNT}/${GATEWAY}/votes` },
+    });
     expect(ok).toBe(true);
   });
 
@@ -679,8 +716,9 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
       domain: "child.example",
       platform: "2.0.0-rc.1",
       app: { ui: { development: "local:ui" } },
+      plugins: { feedback: { extends: `bos://${ACCOUNT}/${GATEWAY}/votes` } },
     };
-    const { ok, violations } = await simulateDeploy(
+    const { ok, violations, bootOk } = await simulateDeploy(
       authoredConfig,
       {
         manifest: "versions/fedcba0987654321.json",
@@ -688,6 +726,7 @@ describe("release-scoped inheritance — a pinned child deploy survives the root
       },
       false,
     );
+    expect(bootOk).toBe(true);
     expect(ok).toBe(false);
     const combined = violations.join("\n");
     expect(combined).toContain("Shared singleton");
diff --git a/packages/everything-dev/tests/unit/composition.test.ts b/packages/everything-dev/tests/unit/composition.test.ts
index e9babb9c..f0c2f9ad 100644
--- a/packages/everything-dev/tests/unit/composition.test.ts
+++ b/packages/everything-dev/tests/unit/composition.test.ts
@@ -176,7 +176,7 @@ describe("stampInheritedSlotsFromRelease", () => {
     expect(outcome.stamped).toEqual([]);
   });
 
-  it("a plugin authored without a ui key stamps its computed ui slot", () => {
+  it("a plugin authored without a ui key still owns the plugin domain — no stamps", () => {
     const authored = {
       plugins: { votes: { extends: "bos://root.near/root" } },
     };
@@ -194,7 +194,49 @@ describe("stampInheritedSlotsFromRelease", () => {
         },
       }),
     });
-    expect(outcome.stamped).toEqual(["plugins.votes.ui"]);
+    expect(outcome.stamped).toEqual([]);
+  });
+
+  it("never stamps plugin slots — a child's declared plugin set owns the whole domain (the rc.26 incident)", () => {
+    const authored = {
+      account: "feedback.near",
+      app: { ui: { production: "https://feedback.test/ui/" } },
+      plugins: {
+        legion: { extends: "bos://root.near/root" },
+        storage: { extends: "bos://root.near/root" },
+      },
+    };
+    const payload = structuredClone(authored);
+    const outcome = stampInheritedSlotsFromRelease({
+      payload,
+      authoredConfig: authored,
+      manifest: manifestWithSlots({
+        "app.auth": {
+          base: authBase,
+          pin: { manifest: "versions/0123456789abcdef.json", integrity: "sha384-auth" },
+        },
+        "app.auth.ui": {
+          base: authUiBase,
+          pin: { manifest: "versions/0123456789abcdef.json", integrity: "sha384-auth-ui" },
+        },
+        "plugins.ai": {
+          base: "https://cdn.test/ai/",
+          pin: { manifest: "ai.json", integrity: "sha384-ai" },
+        },
+        "plugins.ai.ui": {
+          base: "https://cdn.test/ai-ui/",
+          pin: { manifest: "ai-ui.json", integrity: "sha384-ai-ui" },
+        },
+        "plugins.votes": {
+          base: "https://cdn.test/votes/",
+          pin: { manifest: "votes.json", integrity: "sha384-votes" },
+        },
+      }),
+    });
+    expect(outcome.stamped).toEqual(["app.auth", "app.auth.ui"]);
+    // the child's plugin set is exactly what it declared — the parent's
+    // plugins must not appear (and never schema-invalidated ui stamps)
+    expect(payload.plugins).toEqual(authored.plugins);
   });
 });