fix: restore missing keybinding validation guards

persistence.ts imported isActionWithOptionalArgs and isShortcutKey,
neither of which existed at runtime — loading persisted custom
keybindings would crash. Adds actions/guards.ts (excluding required-args
actions per TActionArgsMap) and isShortcutKey in keybinding.ts; the nine
previously dead persistence tests now pass.

3 files changed, 50 insertions, 0 deletions

diff --git a/apps/web/src/actions/guards.ts b/apps/web/src/actions/guards.ts
new file mode 100644
index 00000000..c4fbe8a7
--- /dev/null
+++ b/apps/web/src/actions/guards.ts
@@ -0,0 +1,29 @@
+import { ACTIONS } from "./definitions";
+import type { TActionArgsMap, TActionWithOptionalArgs } from "./types";
+
+type TActionWithRequiredArgs = {
+	[K in keyof TActionArgsMap]: undefined extends TActionArgsMap[K]
+		? never
+		: K;
+}[keyof TActionArgsMap];
+
+/**
+ * Actions that require arguments cannot be bound to a shortcut key — a key
+ * press has no way to supply them. Keep in sync with the required (non-
+ * optional) members of `TActionArgsMap`; the type annotation rejects keys
+ * that are not actually required-args actions.
+ */
+const ACTIONS_WITH_REQUIRED_ARGS: readonly TActionWithRequiredArgs[] = [
+	"remove-media-asset",
+	"remove-media-assets",
+];
+
+export function isActionWithOptionalArgs(
+	action: unknown,
+): action is TActionWithOptionalArgs {
+	return (
+		typeof action === "string" &&
+		action in ACTIONS &&
+		!(ACTIONS_WITH_REQUIRED_ARGS as readonly string[]).includes(action)
+	);
+}
diff --git a/apps/web/src/actions/index.ts b/apps/web/src/actions/index.ts
index 801a846a..d74a31a5 100644
--- a/apps/web/src/actions/index.ts
+++ b/apps/web/src/actions/index.ts
@@ -1,3 +1,4 @@
 export * from "./definitions";
 export * from "./types";
 export * from "./registry";
+export * from "./guards";
diff --git a/apps/web/src/actions/keybinding.ts b/apps/web/src/actions/keybinding.ts
index aeec2fd6..a71b7e98 100644
--- a/apps/web/src/actions/keybinding.ts
+++ b/apps/web/src/actions/keybinding.ts
@@ -32,6 +32,26 @@ export function isKey(value: string): value is Key {
 	return KEY_SET.has(value);
 }
 
+const MODIFIER_KEYS: readonly ModifierKeys[] = [
+	"ctrl",
+	"alt",
+	"shift",
+	"ctrl+shift",
+	"alt+shift",
+	"ctrl+alt",
+	"ctrl+alt+shift",
+];
+
+export function isShortcutKey(value: string): value is ShortcutKey {
+	if (isKey(value)) {
+		return true;
+	}
+	const parts = value.split("+");
+	const key = parts.at(-1) ?? "";
+	const modifiers = parts.slice(0, -1).join("+");
+	return (MODIFIER_KEYS as readonly string[]).includes(modifiers) && isKey(key);
+}
+
 export type ModifierBasedShortcutKey = `${ModifierKeys}+${Key}`;
 // Singular keybindings (these will be disabled when an input-ish area has been focused)
 export type SingleCharacterShortcutKey = `${Key}`;