fix: vision slot filters to image-capable + custom models (was relaxing for all providers)

The prior change made the vision slot show every model (image-capable first),
which relaxed the filter for built-in providers too — built-in text-only models
became selectable for Vision. Centralize the vision rule in ModelMenuList:
built-ins must report image input; custom-endpoint models stay selectable (their
capability may be unreported). Image-capable still float first.

components/settings/agent-section.tsx

@@ -600,10 +600,6 @@ export function AgentSection({
 					const chosen = coord ? catalog?.find((m) => m.id === coord.id && m.provider === coord.provider) : undefined;
 					const levels = chosen ? chosen.supportedLevels : THINKING_LEVELS;
 					const thisMenuOpen = openMenu?.target === slot ? openMenu.kind : null;
-					// Vision slot: image-capable models float first, but all stay
-					// selectable (a custom endpoint that doesn't report modality must
-					// remain pickable) — so this orders, never filters.
-					const slotCatalog = catalog;
 					return (
 						<SettingsRow
 							key={slot}
@@ -648,10 +644,10 @@ export function AgentSection({
 										menuClass="flex w-[22rem] flex-col rounded-xl border border-border bg-card p-2 text-xs shadow-xl"
 									>
 										<ModelMenuList
-											models={slotCatalog ?? undefined}
+											models={catalog ?? undefined}
 											effectiveId={modelId}
 											effectiveProvider={provider}
-											prioritizeImage={slot === "vision"}
+											vision={slot === "vision"}
 											onPick={(entry) => {
 												// Auto-populate (chunk 2, owner: "populate everywhere"): the
 												// fresh pick writes a level — the stored one rides as-is

components/settings/model-menu.tsx

@@ -21,7 +21,7 @@
 
 import { useEffect, useRef, useState } from "react";
 import type { ModelCatalogEntry } from "@/src/core";
-import { fuzzyScore, subscriptionLabel } from "@/src/core";
+import { CUSTOM_PROVIDER, fuzzyScore, subscriptionLabel } from "@/src/core";
 import { formatTokens } from "@/components/usage-format";
 import { SearchMenuList } from "./search-menu-list";
 
@@ -39,7 +39,7 @@ export function ModelMenuList({
 	effectiveProvider,
 	onPick,
 	footer,
-	prioritizeImage,
+	vision,
 }: {
 	/** The full catalog — undefined while it loads. */
 	models: ModelCatalogEntry[] | undefined;
@@ -54,19 +54,25 @@ export function ModelMenuList({
 	onPick: (entry: ModelCatalogEntry) => void;
 	/** Quiet footer note under the list (context-specific). */
 	footer?: string;
-	/** Vision slot: image-capable models float to the top (still all
-	 *  selectable — a custom endpoint that doesn't report modality must
-	 *  stay pickable, so this orders rather than filters). */
-	prioritizeImage?: boolean;
+	/** Vision slot: only image-capable models are selectable — plus every
+	 *  custom-endpoint model, whose capability the endpoint may not report.
+	 *  Image-capable ones float to the top. */
+	vision?: boolean;
 }) {
+	// Vision slot: built-ins must report image input; custom-endpoint models
+	// stay selectable (the endpoint may not report a modality). Image-capable
+	// ones float to the top of the list.
+	const visionItems = vision
+		? models?.filter((m) => m.input.includes("image") || m.provider === CUSTOM_PROVIDER.id)
+		: models;
 	return (
 		<>
 			<SearchMenuList
-				items={models}
+				items={visionItems}
 				itemKey={(m) => `${m.provider}/${m.id}`}
 				searchTerms={(m) => [m.provider, m.id, m.name]}
 				compare={(a, b) => a.id.localeCompare(b.id)}
-				prioritize={prioritizeImage ? (m) => m.input.includes("image") : undefined}
+				prioritize={vision ? (m) => m.input.includes("image") : undefined}
 				isSelected={(m) => m.id === effectiveId && m.provider === (effectiveProvider ?? m.provider)}
 				onPick={onPick}
 				searchTestid="model-search"

components/setup-dialog.tsx

@@ -519,7 +519,9 @@ function OpenSetupDialog({ onClose, onDone }: SetupDialogProps) {
 							// Unavailable metadata cannot erase or clamp a saved preference.
 							const levelsForEntry = metadata?.supportedLevels ?? (entry ? Object.keys(THINKING_LABEL) : []);
 							const available = catalog?.models ?? (failed ? [] : undefined);
-							const slotCatalog = slot === "vision" ? available?.filter((m) => m.input.includes("image")) : available;
+							const slotCatalog = slot === "vision"
+								? available?.filter((m) => m.input.includes("image") || m.provider === CUSTOM_PROVIDER.id)
+								: available;
 							return (
 								<div key={slot} data-testid={`setup-slot-${slot}`} className="flex flex-col gap-1.5">
 									<span className="flex items-center gap-1.5">
@@ -573,7 +575,7 @@ function OpenSetupDialog({ onClose, onDone }: SetupDialogProps) {
 														models={slotCatalog}
 														effectiveId={entry?.id}
 														effectiveProvider={entry?.provider}
-														prioritizeImage={slot === "vision"}
+														vision={slot === "vision"}
 														onPick={(m) => {
 															editedSlots.current.add(slot);
 															setPicked((prev) => ({ ...prev, [slot]: m }));

tests/setup-dialog-interaction.test.tsx

@@ -172,13 +172,15 @@ describe("setup polish interactions", () => {
 		assert.equal(closed, 0);
 	});
 
-	it("the vision slot lists unknown-capability models (image-capable first, nothing hidden)", async () => {
+	it("the vision slot filters out built-in text-only models (image-capable or custom only)", async () => {
 		await mount({ keyed: true });
 		await click(element('[data-testid="setup-trigger-vision"]'));
-		// The text-only fixture stays selectable in the vision slot: the slot
-		// orders image-capable first but no longer filters, so a custom endpoint
-		// that reports no modality can still be picked for Vision.
-		assert.ok(element('[data-testid="setup-menu-vision"]').textContent?.includes("fixture-text"));
+		// The text-only openrouter fixture is neither image-capable nor a custom-
+		// endpoint model, so the vision slot filters it out (built-ins must report
+		// image input; only custom models stay selectable when capability is unknown).
+		const menu = element('[data-testid="setup-menu-vision"]');
+		assert.ok(!menu.textContent?.includes("fixture-text"));
+		assert.ok(menu.textContent?.includes("No models match."));
 	});
 
 	it("catalog failure uses the approved two-sentence error", async () => {