feat: manual model IDs when /models is unavailable

Hosted OpenAI-compatible APIs often serve chat but not GET /models
(Volcengine Ark Agent Plan returns 404), so connect failed. Accept a
typed list of model IDs: merged into discovered models when /models
works, used alone when it does not. The typed list is stored as
customProvider.manualModels so reconnects and pin saves keep it.

src/core/settings-resolution.ts

@@ -99,7 +99,7 @@ export interface EffectiveSettings {
 	compaction: Required<CompactionSettings>;
 	/** Custom endpoint, resolved concrete: baseUrl defaults "", models and
 	 *  user pins default to empty. */
-	customProvider: { baseUrl: string; models: CustomModel[]; overrides: Record<string, CustomModelOverride> };
+	customProvider: { baseUrl: string; models: CustomModel[]; overrides: Record<string, CustomModelOverride>; manualModels: string[] };
 }
 
 /** The conversation pair's chain (BYOK, owner 2026-09-22): the chat's own
@@ -230,6 +230,7 @@ export function resolveSettings(record: UserSettings | null): EffectiveSettings
 			baseUrl: record?.customProvider?.baseUrl ?? "",
 			models: record?.customProvider?.models ?? [],
 			overrides: record?.customProvider?.overrides ?? {},
+			manualModels: record?.customProvider?.manualModels ?? [],
 		},
 	};
 }

src/core/settings.ts

@@ -259,6 +259,13 @@ export interface CustomProviderSettings {
 	/** User pins keyed by model id — pure user intent, never rewritten by
 	 *  discovery, pruned to the endpoint's live ids on connect. */
 	overrides?: Record<string, CustomModelOverride>;
+	manualModels?: string[];
+}
+
+export function parseModelIds(raw: unknown): string[] {
+	const items = typeof raw === "string" ? raw.split(/[\s,]+/) : Array.isArray(raw) ? raw : [];
+	const ids = items.filter((v): v is string => typeof v === "string").map((v) => v.trim()).filter(Boolean);
+	return [...new Set(ids)];
 }
 
 /** Canonical base-URL form (single source): trims, requires absolute http(s),
@@ -644,6 +651,8 @@ function sanitizeCustomProvider(raw: Record<string, unknown>): CustomProviderSet
 	}
 	const overrides = sanitizeCustomModelOverrides(raw.overrides);
 	if (Object.keys(overrides).length) out.overrides = overrides;
+	const manualModels = parseModelIds(raw.manualModels);
+	if (manualModels.length) out.manualModels = manualModels;
 	return out;
 }
 

src/server/custom-provider.ts

@@ -131,6 +131,12 @@ export async function discoverModels(baseUrl: string, apiKey?: string): Promise<
 	}
 }
 
+export function mergeManualModels(discovered: readonly CustomModel[], manualIds: readonly string[]): CustomModel[] {
+	const byId = new Map(discovered.map((m) => [m.id, m]));
+	for (const id of manualIds) if (!byId.has(id)) byId.set(id, { id });
+	return [...byId.values()].sort((a, b) => a.id.localeCompare(b.id));
+}
+
 /** Model rows from a list response ({data:[…]} | {models:[…]} | bare array),
  *  or null if unrecognized. */
 function modelRows(body: unknown): unknown[] | null {