diff --git a/src/shared/bundled-notify-ownership.test.ts b/src/shared/bundled-notify-ownership.test.ts
index 19a7fa679..deb08912c 100644
--- a/src/shared/bundled-notify-ownership.test.ts
+++ b/src/shared/bundled-notify-ownership.test.ts
@@ -111,6 +111,32 @@ describe("ensureBundledNotifyOwnership", () => {
     expect(readConfig(userConfigPath).plugin).toEqual(["team-notify-center", "oh-my-openagent", canonicalEntry])
   })
 
+  test("fails loudly for custom package-based notify plugin id", () => {
+    // given
+    const userConfigPath = join(userConfigDir, "opencode.json")
+    writeFileSync(userConfigPath, JSON.stringify({ plugin: ["@custom/opencode-notify", "oh-my-openagent"] }, null, 2) + "\n")
+
+    // when
+    const run = () => ensureBundledNotifyOwnership({ projectDirectory: projectDir, packageRoot })
+
+    // then
+    expect(run).toThrow("Unsafe external notify plugin ownership detected")
+    expect(readConfig(userConfigPath).plugin).toEqual(["@custom/opencode-notify", "oh-my-openagent"])
+  })
+
+  test("fails loudly for custom tuple-based notify package id", () => {
+    // given
+    const userConfigPath = join(userConfigDir, "opencode.json")
+    writeFileSync(userConfigPath, JSON.stringify({ plugin: [["npm:@custom/opencode-notify@1.2.3", {}], "oh-my-openagent"] }, null, 2) + "\n")
+
+    // when
+    const run = () => ensureBundledNotifyOwnership({ projectDirectory: projectDir, packageRoot })
+
+    // then
+    expect(run).toThrow("Unsafe external notify plugin ownership detected")
+    expect(readConfig(userConfigPath).plugin).toEqual([["npm:@custom/opencode-notify@1.2.3", {}], "oh-my-openagent"])
+  })
+
   test("migrates stale bundled dist/opencode-notify file URL to canonical bundled entry", () => {
     // given
     const userConfigPath = join(userConfigDir, "opencode.json")
diff --git a/src/shared/bundled-notify-ownership.ts b/src/shared/bundled-notify-ownership.ts
index 91b93ac5e..d9dd9202c 100644
--- a/src/shared/bundled-notify-ownership.ts
+++ b/src/shared/bundled-notify-ownership.ts
@@ -66,6 +66,35 @@ function isRecognizedExternalNotifyId(entry: string): boolean {
   return KNOWN_EXTERNAL_NOTIFY_IDS.some((base) => normalized === base || normalized.startsWith(`${base}@`))
 }
 
+function stripNpmPrefix(entry: string): string {
+  return entry.startsWith("npm:") ? entry.slice("npm:".length) : entry
+}
+
+function stripVersionSuffix(entry: string): string {
+  const trimmed = entry.trim()
+  const versionSeparatorIndex = trimmed.lastIndexOf("@")
+  if (versionSeparatorIndex <= 0) return trimmed
+
+  const slashIndex = trimmed.indexOf("/")
+  if (trimmed.startsWith("@") && versionSeparatorIndex <= slashIndex) {
+    return trimmed
+  }
+
+  return trimmed.slice(0, versionSeparatorIndex)
+}
+
+function isCustomPackageNotifyCandidate(entry: string): boolean {
+  const normalized = stripNpmPrefix(entry.trim().toLowerCase())
+  if (normalized.length === 0) return false
+  if (normalized.includes("://")) return false
+
+  const packageIdentifier = stripVersionSuffix(normalized)
+  if (packageIdentifier === "opencode-notify") return true
+  if (/^@[a-z0-9._-]+\/opencode-notify$/i.test(packageIdentifier)) return true
+  if (/^[a-z0-9._-]+\/opencode-notify$/i.test(packageIdentifier)) return true
+  return false
+}
+
 function normalizePathForComparison(pathValue: string): string {
   return resolve(pathValue).replace(/\\/g, "/").replace(/\/+$/, "")
 }
@@ -133,6 +162,15 @@ function classifyPluginEntry(entry: OpenCodePluginEntry, index: number, canonica
       }
     }
 
+    if (isCustomPackageNotifyCandidate(entry)) {
+      return {
+        kind: "unsafe-external",
+        entry,
+        index,
+        reason: "notify package entry is not an exact recognized kdco/notify identifier",
+      }
+    }
+
     return { kind: "other", entry, index }
   }
 
@@ -172,6 +210,15 @@ function classifyPluginEntry(entry: OpenCodePluginEntry, index: number, canonica
     }
   }
 
+  if (isCustomPackageNotifyCandidate(tupleKey)) {
+    return {
+      kind: "unsafe-external",
+      entry,
+      index,
+      reason: "notify package tuple entry is not an exact recognized kdco/notify identifier",
+    }
+  }
+
   return { kind: "other", entry, index }
 }