From 4461c03f1452316404ff7b7716126338f16f44dc Mon Sep 17 00:00:00 2001
From: Richard Gibson <richard.gibson@gmail.com>
Date: Wed, 5 Mar 2025 10:53:40 -0500
Subject: [PATCH] chore: Make a helper type for restricting object keys to
 strings

---
 packages/SwingSet/src/kernel/slogger.js | 4 ++--
 packages/internal/src/types.ts          | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/packages/SwingSet/src/kernel/slogger.js b/packages/SwingSet/src/kernel/slogger.js
index f8037b7ac6a..2bc3aef373b 100644
--- a/packages/SwingSet/src/kernel/slogger.js
+++ b/packages/SwingSet/src/kernel/slogger.js
@@ -2,7 +2,7 @@ import { q } from '@endo/errors';
 import { objectMap } from '@agoric/internal';
 import { makeLimitedConsole } from '@agoric/internal/src/ses-utils.js';
 
-/** @import {Callable} from '@agoric/internal'; */
+/** @import {Callable, OnlyStringKeys} from '@agoric/internal'; */
 /** @import {LimitedConsole} from '@agoric/internal/src/js-utils.js'; */
 
 const IDLE = 'idle';
@@ -31,7 +31,7 @@ const noopFinisher = harden(() => {});
  */
 function addSlogCallbacks(slogCallbacks, unusedMsgPrefix, methods) {
   const unused = new Set(Object.keys(slogCallbacks));
-  const wrappedMethods = /** @type {Methods} */ (
+  const wrappedMethods = /** @type {OnlyStringKeys<Methods>} */ (
     objectMap(methods, (impl, methodKey) => {
       const methodName = /** @type {keyof typeof slogCallbacks} */ (methodKey);
       unused.delete(methodName);
diff --git a/packages/internal/src/types.ts b/packages/internal/src/types.ts
index ce036dd5992..a8db49d2df3 100644
--- a/packages/internal/src/types.ts
+++ b/packages/internal/src/types.ts
@@ -4,6 +4,10 @@ import type { Primitive } from '@endo/pass-style';
 import type { Pattern } from '@endo/patterns';
 import type { Callable } from './ses-utils.js';
 
+export type OnlyStringKeys<O> = {
+  [K in keyof O]: K extends string ? O[K] : never;
+};
+
 /**
  * A map corresponding with a total function such that `get(key)` is assumed to
  * always succeed.