diff --git a/app/api/custom-provider/route.ts b/app/api/custom-provider/route.ts
new file mode 100644
index 0000000..f77ad78
--- /dev/null
+++ b/app/api/custom-provider/route.ts
@@ -0,0 +1,132 @@
+/**
+ * The custom endpoint's connect surface (one provider in the Keys list).
+ *   GET    → non-secret config { baseUrl, models, overrides, manualModels } +
+ *            keyPresent (masked).
+ *   POST   → connect: validate + normalize the base URL, probe /models, store
+ *            the key, persist { baseUrl, models, overrides, manualModels },
+ *            re-sync the provider into piModels(). Discovery lives here because
+ *            connecting and discovering are one user action. A failed probe is
+ *            fatal UNLESS the user typed model IDs: an endpoint that serves chat
+ *            but no model list is configured from those ids alone. A failed
+ *            probe for the endpoint already stored keeps its last snapshot, so
+ *            a blip cannot prune the stored pins. A 401/403 always fails: a
+ *            rejected key is not a missing model list. Stored user pins survive
+ *            a reconnect, pruned to the ids the connect ends up offering.
+ *   PATCH  → store per-model pins only. No probe: pins must be editable with
+ *            the local server switched off (the case they exist for).
+ *   DELETE → disconnect: drop the stored config + the stored key and unregister
+ *            the provider (the mirror image of POST; idempotent).
+ */
+import {
+	deleteKey,
+	discoverModels,
+	effectiveSettings,
+	keyValue,
+	mergeManualModels,
+	parseCustomModelOverridesBody,
+	readSettingsRecord,
+	saveKey,
+	syncCustomProvider,
+	writeSettingsRecord,
+} from "@/src/server";
+import { CUSTOM_PROVIDER, normalizeBaseUrl, parseModelIds, sanitizeCustomModelOverrides } from "@/src/core";
+
+export const dynamic = "force-dynamic";
+
+export async function GET() {
+	const cp = effectiveSettings().customProvider;
+	return Response.json({
+		baseUrl: cp.baseUrl,
+		models: cp.models,
+		overrides: cp.overrides,
+		manualModels: cp.manualModels,
+		keyPresent: keyValue(CUSTOM_PROVIDER.envVar) !== undefined,
+	});
+}
+
+export async function POST(request: Request) {
+	const body = (await request.json().catch(() => null)) as { baseUrl?: unknown; key?: unknown; manualModels?: unknown } | null;
+	const base = normalizeBaseUrl(typeof body?.baseUrl === "string" ? body.baseUrl : "");
+	if (!base) return Response.json({ error: "Base URL must be a valid http(s) URL" }, { status: 400 });
+
+	// Empty key string clears it, absent leaves it stored; only a real key rides the probe.
+	const keyProvided = typeof body?.key === "string";
+	const key = keyProvided ? (body!.key as string).trim() : undefined;
+
+	const manualModels = parseModelIds(body?.manualModels);
+	const record = readSettingsRecord() ?? { version: 1 };
+	const found = await discoverModels(base, key ? key : undefined);
+	// A rejected key is not a missing model list: never let typed ids turn an
+	// auth failure into a stored "connected" endpoint.
+	if (!found.ok && (found.status === 401 || found.status === 403)) {
+		return Response.json({ error: found.error }, { status: 502 });
+	}
+	if (!found.ok && !manualModels.length) {
+		return Response.json({ error: `${found.error}. If this endpoint has no /models list, add model IDs manually.` }, { status: 502 });
+	}
+	// A failed probe says nothing about what the endpoint offers: keep the last
+	// snapshot of the SAME endpoint, so a transient failure cannot shrink the
+	// model list and prune its pins. A different base URL starts clean.
+	const discovered = found.ok
+		? found.models
+		: record.customProvider?.baseUrl === base
+			? (record.customProvider?.models ?? [])
+			: [];
+	const models = mergeManualModels(discovered, manualModels);
+
+	if (keyProvided) {
+		if (key) {
+			const saved = saveKey(CUSTOM_PROVIDER.envVar, key);
+			if (!saved.ok) return Response.json({ error: saved.error }, { status: 400 });
+		} else {
+			deleteKey(CUSTOM_PROVIDER.envVar);
+		}
+	}
+
+	// User pins are never rewritten by discovery — only pruned to the ids this
+	// connect offers (discovered ∪ typed).
+	const overrides = sanitizeCustomModelOverrides(
+		record.customProvider?.overrides,
+		models.map((m) => m.id),
+	);
+	const next = writeSettingsRecord({
+		...record,
+		customProvider: { baseUrl: base, models, overrides, ...(manualModels.length ? { manualModels } : {}) },
+	});
+	syncCustomProvider(next.customProvider);
+	return Response.json({ ok: true, models: next.customProvider?.models ?? [] });
+}
+
+/** Store the per-model pins (replace-whole). Pruned against the STORED model
+ *  list, never a probe — an offline endpoint keeps its pins editable. */
+export async function PATCH(request: Request) {
+	const parsed = parseCustomModelOverridesBody(await request.json().catch(() => null));
+	if (!parsed.ok) return Response.json({ error: parsed.error }, { status: 400 });
+
+	const cp = effectiveSettings().customProvider;
+	if (!cp.baseUrl) return Response.json({ error: "No custom endpoint configured" }, { status: 409 });
+
+	const overrides = sanitizeCustomModelOverrides(
+		parsed.settings,
+		cp.models.map((m) => m.id),
+	);
+	const record = readSettingsRecord() ?? { version: 1 };
+	const next = writeSettingsRecord({
+		...record,
+		customProvider: { baseUrl: cp.baseUrl, models: cp.models, overrides, ...(cp.manualModels.length ? { manualModels: cp.manualModels } : {}) },
+	});
+	syncCustomProvider(next.customProvider);
+	return Response.json({ ok: true, overrides: next.customProvider?.overrides ?? {} });
+}
+
+/** Disconnect: forget the endpoint AND its key, then unregister the provider.
+ *  Deleting the section (rather than blanking baseUrl) keeps settings.json the
+ *  same shape as a never-connected install. Idempotent by construction. */
+export async function DELETE() {
+	const record = readSettingsRecord() ?? { version: 1 };
+	const { customProvider: _dropped, ...rest } = record;
+	const next = writeSettingsRecord(rest);
+	deleteKey(CUSTOM_PROVIDER.envVar);
+	syncCustomProvider(next.customProvider);
+	return Response.json({ ok: true });
+}
diff --git a/components/settings/agent-section.tsx b/components/settings/agent-section.tsx
index 33f5512..6aaeedf 100644
--- a/components/settings/agent-section.tsx
+++ b/components/settings/agent-section.tsx
@@ -600,9 +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 slots pick from image-capable models only.
-					const slotCatalog =
-						slot === "vision" ? catalog?.filter((m) => m.input.includes("image")) : catalog;
 					return (
 						<SettingsRow
 							key={slot}
@@ -647,9 +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}
+											vision={slot === "vision"}
 											onPick={(entry) => {
 												// Auto-populate (chunk 2, owner: "populate everywhere"): the
 												// fresh pick writes a level — the stored one rides as-is
diff --git a/components/settings/keys-section.tsx b/components/settings/keys-section.tsx
index 5d5f18e..a3ddbee 100644
--- a/components/settings/keys-section.tsx
+++ b/components/settings/keys-section.tsx
@@ -24,7 +24,15 @@
  */
 
 import { useEffect, useRef, useState } from "react";
-import { AUTH_KEYS, type AuthKeyStatus } from "@/src/core";
+import {
+	AUTH_KEYS,
+	CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW,
+	CUSTOM_MODEL_DEFAULT_MAX_TOKENS,
+	CUSTOM_PROVIDER,
+	type AuthKeyStatus,
+	type CustomModel,
+	type CustomModelOverride,
+} from "@/src/core";
 import { SettingsGroup } from "./controls.tsx";
 import { SubscriptionConnections } from "./subscription-connections.tsx";
 import { ClaudeCodeInstallationStatus } from "./claude-code-status.tsx";
@@ -46,12 +54,29 @@ interface KeysResponse {
 	providers?: ProviderKeyInfo[];
 }
 
+/** The custom endpoint's non-secret status (GET /api/custom-provider). */
+interface CustomStatus {
+	baseUrl: string;
+	models: CustomModel[];
+	/** User pins by model id (context / max output / thinking). */
+	overrides: Record<string, CustomModelOverride>;
+	manualModels: string[];
+	keyPresent: boolean;
+}
+
 /** The curated tools group, pinned by id (the catalog owns the copy;
  *  these ids are the contract). Derived from the catalog (search wave,
  *  2026-09-20: the Google CSE pair retired, Tavily + Brave joined) — the
  *  section can never drift from core/auth-keys.ts again. */
 const TOOL_IDS = AUTH_KEYS.map((k) => k.id) as readonly string[];
 
+/** The custom endpoint's synthetic Add-provider entry (offered only while unconfigured). */
+export const CUSTOM_PROVIDER_INFO: ProviderKeyInfo = {
+	id: CUSTOM_PROVIDER.id,
+	envVar: CUSTOM_PROVIDER.envVar,
+	label: CUSTOM_PROVIDER.label,
+};
+
 /** The classification driving the table groups. Pure — exported for
  *  tests. OpenRouter is un-pinned (wave-5 owner ruling): no synthesis,
  *  no special row — it rides the same provider classification. */
@@ -84,6 +109,10 @@ export function classifyKeys(
 	const unknownRows: AuthKeyStatus[] = [];
 	for (const s of statuses) {
 		if (isTool(s.id)) continue;
+		// The custom endpoint's key has its OWN home (the Custom endpoint
+		// section), so it never shows here — not as a provider row, not as an
+		// "other stored variable".
+		if (s.id === CUSTOM_PROVIDER.envVar) continue;
 		if (providerEnv.has(s.id) || (!s.info && providers === undefined)) providerRows.push(s);
 		else if (!s.info) unknownRows.push(s);
 		// (pre-interlude catalogs: a curated-but-unclassified status still
@@ -300,7 +329,7 @@ function AddProviderRow({
 				onClick={() => setOpen((v) => !v)}
 				className="flex w-full items-center justify-between gap-3 rounded-sm px-1 py-1.5 text-left font-ui text-xs text-muted-foreground transition-colors hover:bg-accent/50 hover:text-foreground"
 			>
-				<span>+ Add provider key</span>
+				<span>+ Add a provider</span>
 				{addable.length > 0 && <span className="font-mono text-[11px]">{addable.length}</span>}
 			</button>
 			{open && (
@@ -343,13 +372,16 @@ export function KeysSection({
 	/** The paste editor for a freshly chosen Add-provider target. */
 	const [adding, setAdding] = useState<ProviderKeyInfo | null>(null);
 	const [addError, setAddError] = useState<string | null>(null);
+	/** The custom endpoint's status + whether its connect editor is open. */
+	const [custom, setCustom] = useState<CustomStatus | null>(null);
+	const [addingCustom, setAddingCustom] = useState(false);
 
 	// Escape folds any open editor (unfolded row or the Add-provider paste)
 	// WITHOUT closing the dialog. Claimed at document CAPTURE phase — the
 	// only stopPropagation that outruns both the input's React handler and
 	// the dialog's window-level listener.
 	useEffect(() => {
-		if (openRow === null && adding === null) return;
+		if (openRow === null && adding === null && !addingCustom) return;
 		const onKeyDown = (e: KeyboardEvent) => {
 			if (e.key !== "Escape") return;
 			// A language dropdown above this editor in the dismissal stack owns
@@ -359,20 +391,37 @@ export function KeysSection({
 			e.stopPropagation();
 			setOpenRow(null);
 			setAdding(null);
+			setAddingCustom(false);
 		};
 		document.addEventListener("keydown", onKeyDown, true);
 		return () => document.removeEventListener("keydown", onKeyDown, true);
-	}, [openRow, adding]);
+	}, [openRow, adding, addingCustom]);
 
-	const reload = () =>
-		fetch("/api/keys")
-			.then((r) => r.json())
-			.then((body: KeysResponse) => {
-				setStatuses(body.keys ?? []);
-				if (body.providers) setProviders(body.providers);
-			})
-			.catch(() => setStatuses([]))
-			.finally(() => setLoading(false));
+	const reload = async () => {
+		try {
+			const body = (await fetch("/api/keys").then((r) => r.json())) as KeysResponse;
+			setStatuses(body.keys ?? []);
+			if (body.providers) setProviders(body.providers);
+		} catch {
+			setStatuses([]);
+		} finally {
+			setLoading(false);
+		}
+		// Best-effort and independent: the custom endpoint's status must never
+		// blank the provider-key list above if its fetch fails.
+		try {
+			const cp = (await fetch("/api/custom-provider").then((r) => r.json())) as Partial<CustomStatus>;
+			setCustom({
+				baseUrl: cp.baseUrl ?? "",
+				models: cp.models ?? [],
+				overrides: cp.overrides ?? {},
+				manualModels: cp.manualModels ?? [],
+				keyPresent: Boolean(cp.keyPresent),
+			});
+		} catch {
+			/* custom status unavailable — leave it unset */
+		}
+	};
 
 	useEffect(() => {
 		void reload();
@@ -409,6 +458,15 @@ export function KeysSection({
 		notifySettingsSaved("keys");
 	}
 
+	/** Forget the custom endpoint (config + key server-side), same rhythm as
+	 *  deleteKey: fire, re-read, broadcast so the catalog narrows everywhere. */
+	async function disconnectCustom(): Promise<void> {
+		await fetch("/api/custom-provider", { method: "DELETE" }).catch(() => undefined);
+		setAddingCustom(false);
+		await reload();
+		notifySettingsSaved("keys");
+	}
+
 	if (loading || statuses === null) {
 		return <p className="px-6 py-5 text-xs text-muted-foreground/70">Loading keys…</p>;
 	}
@@ -445,12 +503,45 @@ export function KeysSection({
 						testid={`key-${status.id.toLowerCase()}`}
 					/>
 				))}
+				{custom?.baseUrl && (
+					<CustomEndpointRow
+						status={custom}
+						expanded={addingCustom}
+						onToggle={() => setAddingCustom((v) => !v)}
+					/>
+				)}
+				{addingCustom && (
+					<CustomEndpointEditor
+						baseUrl0={custom?.baseUrl ?? ""}
+						keyPresent={custom?.keyPresent ?? false}
+						models={custom?.models ?? []}
+						overrides={custom?.overrides ?? {}}
+						manualModels0={custom?.manualModels ?? []}
+						onSaved={async () => {
+							setAddingCustom(false);
+							await reload();
+							notifySettingsSaved("keys");
+						}}
+						onPinsSaved={async () => {
+							await reload();
+							notifySettingsSaved("keys");
+						}}
+						onDelete={disconnectCustom}
+						onCancel={() => setAddingCustom(false)}
+					/>
+				)}
 				{providers !== undefined && (
 					<AddProviderRow
-						addable={addable}
+						addable={custom?.baseUrl ? addable : [...addable, CUSTOM_PROVIDER_INFO]}
 						onPick={(p) => {
-							setAdding(p);
 							setAddError(null);
+							if (p.id === CUSTOM_PROVIDER.id) {
+								setAdding(null);
+								setAddingCustom(true);
+							} else {
+								setAddingCustom(false);
+								setAdding(p);
+							}
 						}}
 					/>
 				)}
@@ -566,3 +657,320 @@ function AddProviderEditor({
 		</>
 	);
 }
+
+/** The custom endpoint's status row (shown once configured); clicking re-opens the editor. */
+function CustomEndpointRow({
+	status,
+	expanded,
+	onToggle,
+}: {
+	status: CustomStatus;
+	expanded: boolean;
+	onToggle: () => void;
+}) {
+	const count = status.models.length;
+	const line = `${status.baseUrl} · ${count} model${count === 1 ? "" : "s"}${status.keyPresent ? "" : " · keyless"}`;
+	return (
+		<div data-testid="custom-endpoint-row">
+			<button
+				type="button"
+				data-testid="custom-endpoint-row-btn"
+				aria-expanded={expanded}
+				onClick={onToggle}
+				className="flex w-full items-center justify-between gap-3 rounded-sm px-1 py-1.5 text-left cursor-pointer transition-colors hover:bg-accent/50"
+			>
+				<span className="font-ui text-xs text-foreground">Custom endpoint</span>
+				<span data-testid="custom-endpoint-status" className="max-w-[60%] truncate font-mono text-[11px] text-muted-foreground">
+					{line}
+				</span>
+			</button>
+		</div>
+	);
+}
+
+/** A pin row's raw input state — "" means "no pin": the endpoint's own value,
+ *  then the compiled default, decides. `reasoning` is tri-state. */
+interface PinDraft {
+	context: string;
+	maxTokens: string;
+	reasoning: "" | "on" | "off";
+}
+
+const pinDraft = (pin: CustomModelOverride | undefined): PinDraft => ({
+	context: pin?.context === undefined ? "" : String(pin.context),
+	maxTokens: pin?.maxTokens === undefined ? "" : String(pin.maxTokens),
+	reasoning: pin?.reasoning === undefined ? "" : pin.reasoning ? "on" : "off",
+});
+
+/** One draft row per discovered model, seeded from the stored pins. */
+function draftsFor(
+	models: readonly CustomModel[],
+	overrides: Record<string, CustomModelOverride>,
+): Record<string, PinDraft> {
+	return Object.fromEntries(models.map((m) => [m.id, pinDraft(overrides[m.id])]));
+}
+
+/** Drafts → the PATCH payload (replace-whole): a blank field sends nothing and
+ *  a fully blank model is absent — which IS the un-pin. */
+function pinsPayload(drafts: Record<string, PinDraft>): Record<string, CustomModelOverride> {
+	const out: Record<string, CustomModelOverride> = {};
+	for (const [id, d] of Object.entries(drafts)) {
+		const pin: CustomModelOverride = {};
+		if (d.context.trim()) pin.context = Number(d.context);
+		if (d.maxTokens.trim()) pin.maxTokens = Number(d.maxTokens);
+		if (d.reasoning !== "") pin.reasoning = d.reasoning === "on";
+		if (Object.keys(pin).length) out[id] = pin;
+	}
+	return out;
+}
+
+/** testids must survive ids carrying slashes, colons, dots. */
+const pinTestid = (prefix: string, id: string) => `${prefix}-${id.replace(/[^a-z0-9-]/gi, "_")}`;
+
+/** The custom endpoint's connect editor: base URL + key → POST /api/custom-provider
+ *  (validate + discover + register), and the per-model limits form → PATCH (pins,
+ *  no probe, so it works with the local server switched off). Image capability is
+ *  detected automatically. */
+function CustomEndpointEditor({
+	baseUrl0,
+	keyPresent,
+	models,
+	overrides,
+	manualModels0,
+	onSaved,
+	onPinsSaved,
+	onCancel,
+	onDelete,
+}: {
+	baseUrl0: string;
+	keyPresent: boolean;
+	/** The discovered models — one limits row each. */
+	models: readonly CustomModel[];
+	/** Their stored user pins. */
+	overrides: Record<string, CustomModelOverride>;
+	manualModels0: readonly string[];
+	onSaved: () => void | Promise<void>;
+	/** Pins saved — the editor stays open (a form, not a connect). */
+	onPinsSaved: () => void | Promise<void>;
+	onCancel: () => void;
+	onDelete?: () => void | Promise<void>;
+}) {
+	const [baseUrl, setBaseUrl] = useState(baseUrl0);
+	const [key, setKey] = useState("");
+	const [keyTouched, setKeyTouched] = useState(false);
+	const [manualModels, setManualModels] = useState(manualModels0.join(", "));
+	const [busy, setBusy] = useState(false);
+	const [error, setError] = useState<string | null>(null);
+	// The limits form: edited drafts over the stored pins, plus the last saved
+	// payload as the dirty baseline (the server's echo is what gets stored).
+	const [drafts, setDrafts] = useState<Record<string, PinDraft>>(() => draftsFor(models, overrides));
+	const [baseline, setBaseline] = useState(() => JSON.stringify(pinsPayload(draftsFor(models, overrides))));
+	const [pinsBusy, setPinsBusy] = useState(false);
+	const [pinsError, setPinsError] = useState<string | null>(null);
+	// A key is required to enable chatting; local servers accept any value. A
+	// stored key is kept when the field is left blank.
+	const needsKey = !keyPresent;
+	const canConnect = Boolean(baseUrl.trim()) && (!needsKey || Boolean(key.trim()));
+
+	const draftOf = (m: CustomModel): PinDraft => drafts[m.id] ?? pinDraft(overrides[m.id]);
+	const setDraft = (m: CustomModel, patch: Partial<PinDraft>) =>
+		setDrafts((prev) => ({ ...prev, [m.id]: { ...draftOf(m), ...patch } }));
+	const current = Object.fromEntries(models.map((m) => [m.id, draftOf(m)])) as Record<string, PinDraft>;
+	const dirty = JSON.stringify(pinsPayload(current)) !== baseline;
+
+	async function savePins() {
+		if (pinsBusy || !dirty) return;
+		setPinsBusy(true);
+		setPinsError(null);
+		const res = await fetch("/api/custom-provider", {
+			method: "PATCH",
+			headers: { "content-type": "application/json" },
+			body: JSON.stringify({ overrides: pinsPayload(current) }),
+		}).catch(() => null);
+		setPinsBusy(false);
+		if (!res || !res.ok) {
+			const b = (await res?.json().catch(() => ({}))) as { error?: string } | undefined;
+			setPinsError(res ? (b?.error ?? `Save failed (${res.status})`) : "Save failed. Check your connection.");
+			return;
+		}
+		// The server's stored map is the truth (it floors + prunes) — echo it back.
+		const body = (await res.json().catch(() => null)) as { overrides?: Record<string, CustomModelOverride> } | null;
+		const next = draftsFor(models, body?.overrides ?? pinsPayload(current));
+		setDrafts(next);
+		setBaseline(JSON.stringify(pinsPayload(next)));
+		await onPinsSaved();
+	}
+
+	async function save() {
+		if (busy || !baseUrl.trim()) return;
+		setBusy(true);
+		setError(null);
+		const res = await fetch("/api/custom-provider", {
+			method: "POST",
+			headers: { "content-type": "application/json" },
+			body: JSON.stringify({ baseUrl, manualModels, ...(keyTouched ? { key } : {}) }),
+		}).catch(() => null);
+		setBusy(false);
+		if (!res || !res.ok) {
+			const b = (await res?.json().catch(() => ({}))) as { error?: string } | undefined;
+			setError(res ? (b?.error ?? `Connect failed (${res.status})`) : "Connect failed. Check your connection.");
+			return;
+		}
+		await onSaved();
+	}
+
+	return (
+		<div data-testid="custom-endpoint-editor" className="flex flex-col gap-2 rounded-sm px-1 py-1.5">
+			<div className="flex items-center gap-2">
+				<span className="shrink-0 font-ui text-xs text-foreground">Custom endpoint</span>
+				<input
+					type="text"
+					value={baseUrl}
+					onChange={(e) => setBaseUrl(e.target.value)}
+					placeholder="Base URL, e.g. http://localhost:11434/v1"
+					aria-label="Custom endpoint base URL"
+					data-testid="custom-baseurl-input"
+					disabled={busy}
+					autoFocus
+					className="h-7 min-w-0 flex-1 rounded-sm border border-border bg-background px-1.5 font-mono text-xs text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
+				/>
+			</div>
+			<input
+				type="text"
+				value={manualModels}
+				onChange={(e) => setManualModels(e.target.value)}
+				placeholder="Model IDs, comma-separated — optional, needed when the endpoint has no /models list"
+				aria-label="Custom endpoint model IDs"
+				data-testid="custom-models-input"
+				disabled={busy}
+				className="h-7 min-w-0 rounded-sm border border-border bg-background px-1.5 font-mono text-xs text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
+			/>
+			<div className="flex items-center gap-2">
+				<input
+					type="text"
+					value={key}
+					onChange={(e) => {
+						setKey(e.target.value);
+						setKeyTouched(true);
+					}}
+					placeholder={keyPresent ? "Key set — paste to replace, leave empty to keep" : "API key — required (any value works for local servers)"}
+					aria-label="Custom endpoint API key"
+					data-testid="custom-key-input"
+					disabled={busy}
+					className="h-7 min-w-0 flex-1 rounded-sm border border-border bg-background px-1.5 font-mono text-xs text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
+				/>
+				<button
+					type="button"
+					onClick={() => void save()}
+					disabled={busy || !canConnect}
+					data-testid="custom-save"
+					className="shrink-0 text-xs text-foreground underline-offset-2 hover:underline disabled:text-muted-foreground/40 disabled:no-underline"
+				>
+					{busy ? "Connecting…" : "Connect"}
+				</button>
+				<button
+					type="button"
+					onClick={onCancel}
+					disabled={busy}
+					data-testid="custom-cancel"
+					className="shrink-0 text-xs text-muted-foreground/70 underline-offset-2 hover:text-foreground hover:underline"
+				>
+					Cancel
+				</button>
+				{/* Disconnect rides beside Connect, exactly the stored-key rows' Delete:
+				    quiet text, one click, no confirm — and only once there IS an
+				    endpoint (a fresh add has nothing to delete). */}
+				{onDelete && baseUrl0.trim() && (
+					<button
+						type="button"
+						onClick={() => void onDelete()}
+						disabled={busy}
+						data-testid="custom-delete"
+						className="shrink-0 text-xs text-muted-foreground/70 underline-offset-2 hover:text-red-500 hover:underline"
+					>
+						Disconnect
+					</button>
+				)}
+			</div>
+			{models.length > 0 && (
+				<div className="flex flex-col gap-1" data-testid="custom-pins">
+					<span className="text-[11px] text-muted-foreground">
+						Model limits — blank uses the endpoint’s value, then the default
+					</span>
+					<div className="flex max-h-56 flex-col gap-1 overflow-y-auto pr-1">
+						{models.map((m) => {
+							const d = draftOf(m);
+							return (
+								<div key={m.id} className="flex items-center gap-2" data-testid={pinTestid("custom-pin-row", m.id)}>
+									<span className="min-w-0 flex-1 truncate font-mono text-[11px] text-foreground" title={m.id}>
+										{m.id}
+									</span>
+									<input
+										type="text"
+										inputMode="numeric"
+										value={d.context}
+										onChange={(e) => setDraft(m, { context: e.target.value })}
+										placeholder={String(m.context ?? CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW)}
+										aria-label={`${m.id} context window in tokens`}
+										data-testid={pinTestid("custom-pin-context", m.id)}
+										disabled={pinsBusy}
+										className="h-7 w-20 shrink-0 rounded-sm border border-border bg-background px-1.5 text-right font-mono text-[11px] text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
+									/>
+									<input
+										type="text"
+										inputMode="numeric"
+										value={d.maxTokens}
+										onChange={(e) => setDraft(m, { maxTokens: e.target.value })}
+										placeholder={String(m.maxTokens ?? CUSTOM_MODEL_DEFAULT_MAX_TOKENS)}
+										aria-label={`${m.id} max output tokens`}
+										data-testid={pinTestid("custom-pin-maxtokens", m.id)}
+										disabled={pinsBusy}
+										className="h-7 w-20 shrink-0 rounded-sm border border-border bg-background px-1.5 text-right font-mono text-[11px] text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
+									/>
+									<select
+										value={d.reasoning}
+										onChange={(e) => setDraft(m, { reasoning: e.target.value as PinDraft["reasoning"] })}
+										aria-label={`${m.id} thinking`}
+										data-testid={pinTestid("custom-pin-reasoning", m.id)}
+										disabled={pinsBusy}
+										className="h-7 shrink-0 rounded-sm border border-border bg-background px-1 font-ui text-[11px] text-foreground outline-none focus:border-muted-foreground/50"
+									>
+										<option value="">think: auto</option>
+										<option value="on">think: on</option>
+										<option value="off">think: off</option>
+									</select>
+								</div>
+							);
+						})}
+					</div>
+					<div className="flex items-center gap-2">
+						<button
+							type="button"
+							onClick={() => void savePins()}
+							disabled={pinsBusy || !dirty}
+							data-testid="custom-pins-save"
+							className="shrink-0 text-xs text-foreground underline-offset-2 hover:underline disabled:text-muted-foreground/40 disabled:no-underline"
+						>
+							{pinsBusy ? "Saving…" : "Save limits"}
+						</button>
+						{pinsError && (
+							<p role="alert" data-testid="custom-pins-error" className="text-[11px] text-red-500">
+								{pinsError}
+							</p>
+						)}
+					</div>
+				</div>
+			)}
+			{needsKey && (
+				<p className="text-[11px] text-muted-foreground">
+					A key is required to enable chatting — local servers (Ollama, LM Studio) accept any value.
+				</p>
+			)}
+			{error && (
+				<p role="alert" data-testid="custom-error" className="text-xs text-red-500">
+					{error}
+				</p>
+			)}
+		</div>
+	);
+}
diff --git a/components/settings/model-menu.tsx b/components/settings/model-menu.tsx
index 678ba09..35db3be 100644
--- a/components/settings/model-menu.tsx
+++ b/components/settings/model-menu.tsx
@@ -21,7 +21,7 @@
 
 import { useEffect, useRef, useState } from "react";
 import type { ModelCatalogEntry } from "@/src/core";
-import { CLAUDE_CODE_PROVIDER, fuzzyScore, subscriptionLabel } from "@/src/core";
+import { CLAUDE_CODE_PROVIDER, CUSTOM_PROVIDER, fuzzyScore, subscriptionLabel } from "@/src/core";
 import { formatTokens } from "@/components/usage-format";
 import { SearchMenuList } from "./search-menu-list";
 
@@ -40,6 +40,7 @@ export function ModelMenuList({
 	effectiveProvider,
 	onPick,
 	footer,
+	vision,
 }: {
 	/** The full catalog — undefined while it loads. */
 	models: ModelCatalogEntry[] | undefined;
@@ -54,14 +55,25 @@ export function ModelMenuList({
 	onPick: (entry: ModelCatalogEntry) => void;
 	/** Quiet footer note under the list (context-specific). */
 	footer?: string;
+	/** 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={vision ? (m) => m.input.includes("image") : undefined}
 				isSelected={(m) => m.id === effectiveId && m.provider === (effectiveProvider ?? m.provider)}
 				onPick={onPick}
 				searchTestid="model-search"
diff --git a/components/settings/search-menu-list.tsx b/components/settings/search-menu-list.tsx
index 08a4fa6..f864e3a 100644
--- a/components/settings/search-menu-list.tsx
+++ b/components/settings/search-menu-list.tsx
@@ -7,7 +7,7 @@ import { fuzzyScore } from "@/src/core";
  * Models and dictation languages supply only their catalog and row content.
  * The caller owns the shared MenuShell and dismissal behavior. */
 export function SearchMenuList<T>({
-	items, itemKey, searchTerms, compare, isSelected, onPick, renderItem,
+	items, itemKey, searchTerms, compare, prioritize, isSelected, onPick, renderItem,
 	searchTestid, listTestid, optionTestid, placeholder, ariaLabel, loading, empty,
 	disabled = false,
 }: {
@@ -15,6 +15,10 @@ export function SearchMenuList<T>({
 	itemKey: (item: T) => string;
 	searchTerms: (item: T) => string[];
 	compare?: (a: T, b: T) => number;
+	/** Optional grouping key: items it answers true for sort ahead of the
+	 *  rest, fuzzy rank still deciding within each group (a stable partition,
+	 *  never a filter — nothing is hidden). */
+	prioritize?: (item: T) => boolean;
 	isSelected: (item: T) => boolean;
 	onPick: (item: T) => void;
 	renderItem: (item: T) => ReactNode;
@@ -41,7 +45,12 @@ export function SearchMenuList<T>({
 	const results = (items ?? [])
 		.map((item) => ({ item, score: fuzzyScore(query, ...searchTerms(item)) }))
 		.filter((result) => result.score !== null)
-		.sort((a, b) => b.score! - a.score! || (compare?.(a.item, b.item) ?? 0))
+		.sort(
+			(a, b) =>
+				(prioritize ? Number(prioritize(b.item)) - Number(prioritize(a.item)) : 0) ||
+				b.score! - a.score! ||
+				(compare?.(a.item, b.item) ?? 0),
+		)
 		.map(({ item }) => item);
 
 	return <>
diff --git a/components/setup-cta.tsx b/components/setup-cta.tsx
index 299715d..347dd9f 100644
--- a/components/setup-cta.tsx
+++ b/components/setup-cta.tsx
@@ -16,10 +16,9 @@
  */
 
 import { useEffect, useState } from "react";
-import { MODEL_SLOTS, type AuthKeyStatus } from "@/src/core";
+import { CUSTOM_PROVIDER, MODEL_SLOTS, type AuthKeyStatus, type ModelCatalogResponse } from "@/src/core";
 import { classifyKeys, type ProviderKeyInfo } from "@/components/settings/keys-section";
 import { useModelCatalog } from "@/components/model-catalog";
-import type { ModelCatalogResponse } from "@/src/core";
 
 /** Pure: does a MODEL-PROVIDER key exist among the statuses? Reuses
  *  classifyKeys (the keys section's own classification — no drift):
@@ -30,7 +29,13 @@ export function hasProviderKey(
 	statuses: readonly AuthKeyStatus[],
 	providers: readonly ProviderKeyInfo[] | undefined,
 ): boolean {
-	return classifyKeys(statuses, providers).providerRows.some((s) => s.present);
+	// A stored custom-endpoint key counts too: classifyKeys drops it from
+	// providerRows (it has its own dedicated row), but a connected custom
+	// endpoint IS a way to run inference, so it clears the zero-keys gate.
+	return (
+		classifyKeys(statuses, providers).providerRows.some((s) => s.present) ||
+		statuses.some((s) => s.id === CUSTOM_PROVIDER.envVar && s.present)
+	);
 }
 
 /** Completeness is saved identity, not current provider availability. */
diff --git a/components/setup-dialog.tsx b/components/setup-dialog.tsx
index 053f3eb..98b6ad7 100644
--- a/components/setup-dialog.tsx
+++ b/components/setup-dialog.tsx
@@ -40,7 +40,7 @@ import { useEffect, useRef, useState } from "react";
 import { createPortal } from "react-dom";
 import { useBackdropDismiss } from "@/components/backdrop-dismiss";
 import type React from "react";
-import { type ModelCatalogEntry, type ModelSlotName, type ModelsSettings } from "@/src/core";
+import { type ModelCatalogEntry, type ModelSlotName, type ModelsSettings, CUSTOM_PROVIDER } from "@/src/core";
 import { prettyModel } from "@/components/usage-format";
 import { ModelMenuList } from "@/components/settings/model-menu";
 import { MenuShell } from "@/components/menu-shell";
@@ -48,7 +48,7 @@ import { notifySettingsSaved, useSettingsSaved } from "@/components/settings-sig
 import { useModelCatalog } from "@/components/model-catalog";
 import { savedSlotsConfigured } from "@/components/setup-cta";
 import { Hint } from "@/components/ui/hint";
-import { type ProviderKeyInfo } from "@/components/settings/keys-section";
+import { type ProviderKeyInfo, CUSTOM_PROVIDER_INFO } from "@/components/settings/keys-section";
 import { ProviderMenuList } from "@/components/settings/model-menu";
 import { ChatGPTBackgroundAccess } from "@/components/settings/chatgpt-connection";
 import { NativeSubscriptionBackgroundAccess, SubscriptionConnections } from "@/components/settings/subscription-connections";
@@ -134,6 +134,9 @@ export function SetupKeysBody({
 	onValue,
 	onSave,
 	menuAnchor,
+	isCustom,
+	baseUrl,
+	onBaseUrl,
 }: {
 	/** The full provider roster (GET /api/keys providers) — undefined
 	 *  while it loads; the picker renders an honest empty state then. */
@@ -151,6 +154,11 @@ export function SetupKeysBody({
 	onSave: () => void;
 	/** The MenuShell anchor — wired by the wrapper (its triggerRef). */
 	menuAnchor: React.RefObject<HTMLDivElement | null>;
+	/** Chosen provider is the custom endpoint: a base URL field joins the key
+	 *  field. All three optional so plain-key callers (and tests) stay unchanged. */
+	isCustom?: boolean;
+	baseUrl?: string;
+	onBaseUrl?: (v: string) => void;
 }) {
 	return (
 		<div className="flex flex-col gap-3 px-6 py-5" data-testid="setup-stage-keys">
@@ -185,30 +193,44 @@ export function SetupKeysBody({
 					)}
 				</div>
 				{provider && (
-					<div className="flex max-w-96 items-center gap-2">
-						<input
-							type="text"
-							value={value}
-							onChange={(e) => onValue(e.target.value)}
-							onKeyDown={(e) => {
-								if (e.key === "Enter" && value.trim()) onSave();
-							}}
-							placeholder="Paste key…"
-							aria-label={`${provider.label} key`}
-							data-testid="setup-key-input"
-							disabled={saving}
-							autoFocus
-							className="h-7 min-w-0 flex-1 rounded-sm border border-border bg-background px-1.5 font-mono text-xs text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
-						/>
-						<button
-							type="button"
-							onClick={onSave}
-							disabled={saving || !value.trim()}
-							data-testid="setup-key-save"
-							className="shrink-0 rounded-sm border border-border bg-background px-3 py-1.5 font-ui text-xs text-foreground transition-colors hover:border-muted-foreground/50 disabled:cursor-not-allowed disabled:opacity-40"
-						>
-							{saving ? "Saving…" : "Save key"}
-						</button>
+					<div className="flex max-w-96 flex-col gap-2">
+						{isCustom && (
+							<input
+								type="text"
+								value={baseUrl ?? ""}
+								onChange={(e) => onBaseUrl?.(e.target.value)}
+								placeholder="Base URL, e.g. http://localhost:11434/v1"
+								aria-label="Custom endpoint base URL"
+								data-testid="setup-custom-baseurl"
+								disabled={saving}
+								className="h-7 w-full rounded-sm border border-border bg-background px-1.5 font-mono text-xs text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
+							/>
+						)}
+						<div className="flex items-center gap-2">
+							<input
+								type="text"
+								value={value}
+								onChange={(e) => onValue(e.target.value)}
+								onKeyDown={(e) => {
+									if (e.key === "Enter" && value.trim()) onSave();
+								}}
+								placeholder={isCustom ? "API key — required (any value works for local servers)" : "Paste key…"}
+								aria-label={`${provider.label} key`}
+								data-testid="setup-key-input"
+								disabled={saving}
+								autoFocus
+								className="h-7 min-w-0 flex-1 rounded-sm border border-border bg-background px-1.5 font-mono text-xs text-foreground outline-none placeholder:text-muted-foreground/60 focus:border-muted-foreground/50"
+							/>
+							<button
+								type="button"
+								onClick={onSave}
+								disabled={saving || !value.trim()}
+								data-testid="setup-key-save"
+								className="shrink-0 rounded-sm border border-border bg-background px-3 py-1.5 font-ui text-xs text-foreground transition-colors hover:border-muted-foreground/50 disabled:cursor-not-allowed disabled:opacity-40"
+							>
+								{saving ? "Saving…" : isCustom ? "Connect" : "Save key"}
+							</button>
+						</div>
 					</div>
 				)}
 				{error && (
@@ -264,6 +286,7 @@ function OpenSetupDialog({ onClose, onDone }: SetupDialogProps) {
 	const [keyProviders, setKeyProviders] = useState<ProviderKeyInfo[] | undefined>(undefined);
 	const [keyProvider, setKeyProvider] = useState<ProviderKeyInfo | null>(null);
 	const [keyValue, setKeyValue] = useState("");
+	const [customBaseUrl, setCustomBaseUrl] = useState("");
 	const [keySaving, setKeySaving] = useState(false);
 	const [keyError, setKeyError] = useState<string | null>(null);
 	const [keyMenuOpen, setKeyMenuOpen] = useState(false);
@@ -374,14 +397,23 @@ function OpenSetupDialog({ onClose, onDone }: SetupDialogProps) {
 	 *  close recovery or advance to the missing model slots. Shape-gate
 	 *  400s keep their user-facing line inline. */
 	async function saveKey() {
-		if (!keyProvider || !keyValue.trim() || keySaving) return;
+		if (!keyProvider || keySaving) return;
+		const isCustom = keyProvider.id === CUSTOM_PROVIDER.id;
+		if (!keyValue.trim()) return;
 		setKeySaving(true);
 		setKeyError(null);
-		const res = await fetch(`/api/keys/${encodeURIComponent(keyProvider.envVar)}`, {
-			method: "PUT",
-			headers: { "content-type": "application/json" },
-			body: JSON.stringify({ value: keyValue }),
-		}).catch(() => null);
+		// Custom endpoint connects through its own route; every other provider is a plain key PUT.
+		const res = isCustom
+			? await fetch("/api/custom-provider", {
+					method: "POST",
+					headers: { "content-type": "application/json" },
+					body: JSON.stringify({ baseUrl: customBaseUrl, key: keyValue }),
+				}).catch(() => null)
+				: await fetch(`/api/keys/${encodeURIComponent(keyProvider.envVar)}`, {
+						method: "PUT",
+						headers: { "content-type": "application/json" },
+						body: JSON.stringify({ value: keyValue }),
+					}).catch(() => null);
 		setKeySaving(false);
 		if (!res || !res.ok) {
 			const body = (await res?.json().catch(() => ({}))) as { error?: string } | undefined;
@@ -390,6 +422,7 @@ function OpenSetupDialog({ onClose, onDone }: SetupDialogProps) {
 		}
 		setKeyProvider(null);
 		setKeyValue("");
+		setCustomBaseUrl("");
 		notifySettingsSaved("keys");
 	}
 
@@ -420,13 +453,16 @@ function OpenSetupDialog({ onClose, onDone }: SetupDialogProps) {
 	}
 
 	const keysBody = <SetupKeysBody
-		providers={keyProviders}
+		providers={keyProviders ? [...keyProviders, CUSTOM_PROVIDER_INFO] : undefined}
 		provider={keyProvider}
 		value={keyValue}
 		saving={keySaving}
 		error={keyError}
 		menuOpen={keyMenuOpen}
 		menuAnchor={keyTriggerRef}
+		isCustom={keyProvider?.id === CUSTOM_PROVIDER.id}
+		baseUrl={customBaseUrl}
+		onBaseUrl={setCustomBaseUrl}
 		onToggleMenu={() => setKeyMenuOpen((v) => !v)}
 		onPick={(p) => { setKeyProvider(p); setKeyMenuOpen(false); setKeyError(null); }}
 		onValue={setKeyValue}
@@ -483,7 +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">
@@ -537,6 +575,7 @@ function OpenSetupDialog({ onClose, onDone }: SetupDialogProps) {
 														models={slotCatalog}
 														effectiveId={entry?.id}
 														effectiveProvider={entry?.provider}
+														vision={slot === "vision"}
 														onPick={(m) => {
 															editedSlots.current.add(slot);
 															setPicked((prev) => ({ ...prev, [slot]: m }));
diff --git a/src/core/auth-keys.ts b/src/core/auth-keys.ts
index e8e5cc9..492ff15 100644
--- a/src/core/auth-keys.ts
+++ b/src/core/auth-keys.ts
@@ -122,6 +122,19 @@ export const AUTH_PROVIDER_KEYS: readonly AuthProviderInfo[] = [
 	{ id: "zai-coding-cn", envVar: "ZAI_CODING_CN_API_KEY", label: "Z.AI Coding CN" },
 ] as const;
 
+/**
+ * THE single custom endpoint's identity: a user-configured OpenAI-compatible
+ * server registered into pi-ai at runtime (server/custom-provider.ts). NOT part
+ * of AUTH_PROVIDER_KEYS (that table is test-pinned to pi-ai's built-ins and is
+ * env-var-keyed); this one is keyed by a user-supplied base URL, and its key
+ * rides this reserved env var (optional — keyless local servers allowed).
+ */
+export const CUSTOM_PROVIDER = {
+	id: "custom",
+	envVar: "CUSTOM_OPENAI_API_KEY",
+	label: "Custom endpoint",
+} as const;
+
 /** Every distinct env var a model-provider key rides in (the write side's
  *  writability check — see isProviderEnvVar below; also drives which
  *  PRESENT provider vars surface as status rows). */
diff --git a/src/core/settings-resolution.ts b/src/core/settings-resolution.ts
index 1a1cbf9..ca63d6a 100644
--- a/src/core/settings-resolution.ts
+++ b/src/core/settings-resolution.ts
@@ -37,6 +37,8 @@ import {
 	type GeneralSettings,
 	type DictationSettings,
 	type CompactionSettings,
+	type CustomModel,
+	type CustomModelOverride,
 	type GraphSettings,
 	type ModelSlot,
 	type ModelSlotName,
@@ -95,6 +97,9 @@ export interface EffectiveSettings {
 	/** Compaction (owner round 14): resolved concrete — absent record
 	 *  section resolves to the factory 150k. */
 	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>; manualModels: string[] };
 }
 
 /** The conversation pair's chain (BYOK, owner 2026-09-22): the chat's own
@@ -221,6 +226,12 @@ export function resolveSettings(record: UserSettings | null): EffectiveSettings
 		compaction: {
 			thresholdTokens: record?.compaction?.thresholdTokens ?? FACTORY_SETTINGS.compaction.thresholdTokens,
 		},
+		customProvider: {
+			baseUrl: record?.customProvider?.baseUrl ?? "",
+			models: record?.customProvider?.models ?? [],
+			overrides: record?.customProvider?.overrides ?? {},
+			manualModels: record?.customProvider?.manualModels ?? [],
+		},
 	};
 }
 
diff --git a/src/core/settings.ts b/src/core/settings.ts
index 2e8d3ae..8dc6a37 100644
--- a/src/core/settings.ts
+++ b/src/core/settings.ts
@@ -208,6 +208,96 @@ export interface ModelsSettings {
 	vision?: ModelSlot;
 }
 
+// ─── Custom OpenAI-compatible endpoint ───────────────────────────────────────
+// ONE user-configured OpenAI-compatible server (vLLM / Ollama / a proxy). It is
+// one more provider in the Keys list, keyed by a base URL instead of an env var.
+// NON-SECRET config only (base URL + discovered model ids); the API key is a
+// secret in the auth store, never here. Registered into pi-ai as a normal
+// provider (server/custom-provider.ts).
+
+/** Defaults for a custom model — self-hosted endpoints are free. */
+export const CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW = 8192;
+export const CUSTOM_MODEL_DEFAULT_MAX_TOKENS = 4096;
+
+/** Floor for a user-pinned token count (owner, 2026-10-27): the read side
+ *  clamps up, the write side rejects below — the compaction-floor discipline.
+ *  Pins exist because endpoints that publish no limits (LM Studio) otherwise
+ *  sit on the 8192 default with no way to say better. */
+export const CUSTOM_MODEL_PIN_FLOOR = 2_048;
+
+/** One discovered custom model. `image`/`reasoning`/`context`/`maxTokens` are
+ *  detected from the endpoint's /models metadata; anything it omits falls back
+ *  to a default. */
+export interface CustomModel {
+	id: string;
+	/** Accepts image input (Vision-capable). Default false (text-only). */
+	image?: boolean;
+	/** Accepts a reasoning effort (thinking). Default false → the only
+	 *  thinking level is "off", exactly like a non-reasoning built-in. */
+	reasoning?: boolean;
+	/** Context window in tokens, from the endpoint. Absent → the default. */
+	context?: number;
+	/** Max output tokens, from the endpoint. Absent → the default. */
+	maxTokens?: number;
+}
+
+/** A user pin for one custom model: it beats what the endpoint publishes
+ *  (owner ruling — explicit user intent wins; a local server's number is
+ *  often wrong or absent). Absent field = no pin. `reasoning` is tri-state:
+ *  true forces thinking on, false forces it off (a server that advertises
+ *  reasoning but rejects reasoning_effort), absent = what discovery found. */
+export interface CustomModelOverride {
+	context?: number;
+	maxTokens?: number;
+	reasoning?: boolean;
+}
+
+/** The single custom endpoint's stored config (delta section). */
+export interface CustomProviderSettings {
+	/** Normalized base URL (see normalizeBaseUrl). Empty/absent = not configured. */
+	baseUrl?: string;
+	/** Models this endpoint offers: advertised ids merged with the typed
+	 *  manual ones (rewritten on connect; a failed probe keeps the same
+	 *  endpoint's last snapshot). */
+	models?: CustomModel[];
+	/** User pins keyed by model id — pure user intent, never rewritten by
+	 *  discovery, pruned on connect to the ids that connect offers. */
+	overrides?: Record<string, CustomModelOverride>;
+	/** Model ids the user typed by hand, for an endpoint that publishes no
+	 *  usable /models list. Kept apart from the snapshot so a reconnect can
+	 *  re-merge them after discovery refreshes. */
+	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),
+ *  drops trailing slashes. Returns "" for anything invalid ("not configured"). */
+export function normalizeBaseUrl(raw: string): string {
+	const value = raw.trim();
+	if (!value) return "";
+	let url: URL;
+	try {
+		url = new URL(value);
+	} catch {
+		return "";
+	}
+	if (url.protocol !== "http:" && url.protocol !== "https:") return "";
+	return url.toString().replace(/\/+$/, "");
+}
+
+/** THE single source of "is the custom endpoint usable?": a non-empty base URL.
+ *  Key presence is deliberately excluded (keyless local servers are allowed). */
+export function customProviderUsable(
+	cp: CustomProviderSettings | undefined,
+): cp is CustomProviderSettings & { baseUrl: string } {
+	return Boolean(cp?.baseUrl);
+}
+
 /** First-run gate (model-slots wave, owner 2026-09-20): the app refuses
  *  to start chats until the user has actively picked all three slots —
  *  there ARE no defaults for 33 providers; a configured app is one whose
@@ -375,6 +465,8 @@ export interface UserSettings {
 	agent?: AgentSettings;
 	/** The strong/cheap/vision model slots (model slots wave, 2026-09-20). */
 	models?: ModelsSettings;
+	/** The custom OpenAI-compatible endpoint (non-secret config only). */
+	customProvider?: CustomProviderSettings;
 	appearance?: AppearanceSettings;
 	graph?: GraphSettings;
 	compaction?: CompactionSettings;
@@ -501,6 +593,78 @@ function sanitizeModels(raw: Record<string, unknown>): ModelsSettings {
 	return out;
 }
 
+/** A positive integer, or undefined — keeps only meaningful token counts. */
+function positiveInt(value: unknown): number | undefined {
+	return typeof value === "number" && Number.isInteger(value) && value > 0 ? value : undefined;
+}
+
+/** One pin, clamped up to the floor (clamp-never-reject on read). */
+function sanitizeCustomModelOverride(raw: unknown): CustomModelOverride | undefined {
+	if (raw === null || typeof raw !== "object" || Array.isArray(raw)) return undefined;
+	const rec = raw as Record<string, unknown>;
+	const out: CustomModelOverride = {};
+	const context = positiveInt(rec.context);
+	if (context) out.context = Math.max(CUSTOM_MODEL_PIN_FLOOR, context);
+	const maxTokens = positiveInt(rec.maxTokens);
+	if (maxTokens) out.maxTokens = Math.max(CUSTOM_MODEL_PIN_FLOOR, maxTokens);
+	if (typeof rec.reasoning === "boolean") out.reasoning = rec.reasoning;
+	return Object.keys(out).length ? out : undefined;
+}
+
+/** THE pins map + THE prune law: well-formed entries only, ids trimmed, and
+ *  when `liveIds` is given every entry for a model the endpoint no longer
+ *  advertises drops. POST passes the discovered ids, PATCH the stored list. */
+export function sanitizeCustomModelOverrides(
+	raw: unknown,
+	liveIds?: Iterable<string>,
+): Record<string, CustomModelOverride> {
+	const out: Record<string, CustomModelOverride> = {};
+	if (raw === null || typeof raw !== "object" || Array.isArray(raw)) return out;
+	const live = liveIds ? new Set(liveIds) : undefined;
+	for (const [key, value] of Object.entries(raw)) {
+		const id = key.trim();
+		if (!id || (live && !live.has(id))) continue;
+		const pin = sanitizeCustomModelOverride(value);
+		if (pin) out[id] = pin;
+	}
+	return out;
+}
+
+/** The customProvider section: normalized base URL (invalid → dropped) and
+ *  discovered models (ids trimmed, dupes/empties dropped; image kept only when
+ *  true; token counts only as positive ints). Clamp-never-reject. */
+function sanitizeCustomProvider(raw: Record<string, unknown>): CustomProviderSettings {
+	const out: CustomProviderSettings = {};
+	if (typeof raw.baseUrl === "string") {
+		const base = normalizeBaseUrl(raw.baseUrl);
+		if (base) out.baseUrl = base;
+	}
+	if (Array.isArray(raw.models)) {
+		const byId = new Map<string, CustomModel>();
+		for (const m of raw.models) {
+			if (typeof m !== "object" || m === null) continue;
+			const rec = m as Record<string, unknown>;
+			if (typeof rec.id !== "string") continue;
+			const id = rec.id.trim();
+			if (!id) continue;
+			const model: CustomModel = { id };
+			if (rec.image === true) model.image = true;
+			if (rec.reasoning === true) model.reasoning = true;
+			const context = positiveInt(rec.context);
+			if (context) model.context = context;
+			const maxTokens = positiveInt(rec.maxTokens);
+			if (maxTokens) model.maxTokens = maxTokens;
+			byId.set(id, model);
+		}
+		out.models = [...byId.values()];
+	}
+	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;
+}
+
 function sanitizeBooleanMap(raw: unknown): Record<string, boolean> | undefined {
 	if (raw === null || typeof raw !== "object" || Array.isArray(raw)) return undefined;
 	const out: Record<string, boolean> = {};
@@ -651,6 +815,9 @@ export function sanitizeUserSettings(raw: unknown): UserSettings | null {
 		const models = sanitizeModels(r.models as Record<string, unknown>);
 		if (Object.keys(models).length) out.models = models;
 	}
+	if (r.customProvider !== null && typeof r.customProvider === "object" && !Array.isArray(r.customProvider)) {
+		out.customProvider = sanitizeCustomProvider(r.customProvider as Record<string, unknown>);
+	}
 	if (r.graph !== null && typeof r.graph === "object" && !Array.isArray(r.graph)) {
 		out.graph = sanitizeGraph(r.graph as Record<string, unknown>);
 		if (r.compaction !== undefined && r.compaction !== null && typeof r.compaction === "object") {
diff --git a/src/server/custom-provider.ts b/src/server/custom-provider.ts
new file mode 100644
index 0000000..2d947e6
--- /dev/null
+++ b/src/server/custom-provider.ts
@@ -0,0 +1,231 @@
+/**
+ * The custom OpenAI-compatible endpoint: turns the user's non-secret config
+ * (base URL + discovered models) into a pi-ai provider registered in
+ * `piModels()`, so its models fill the same slots as any built-in. Keyless
+ * local servers work via a placeholder key resolved at request time.
+ */
+
+import { createProvider, type ApiKeyAuth, type Api, type Model, type Provider } from "@earendil-works/pi-ai";
+import { openAICompletionsApi } from "@earendil-works/pi-ai/api/openai-completions.lazy";
+import { piModels } from "../agent/models.ts";
+import { CUSTOM_PROVIDER } from "../core/auth-keys.ts";
+import {
+	CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW,
+	CUSTOM_MODEL_DEFAULT_MAX_TOKENS,
+	customProviderUsable,
+	normalizeBaseUrl,
+	type CustomModel,
+	type CustomModelOverride,
+	type CustomProviderSettings,
+} from "../core/settings.ts";
+import { keyValue } from "./keys.ts";
+
+/** Placeholder bearer for keyless endpoints (the OpenAI client needs *a* key). */
+const KEYLESS_PLACEHOLDER = "not-needed";
+
+/** Narrow an unknown to a plain object (not null, not an array). */
+const isRecord = (value: unknown): value is Record<string, unknown> =>
+	typeof value === "object" && value !== null && !Array.isArray(value);
+
+/** Auth: the reserved key via the keys seam, else the keyless placeholder. */
+const customEndpointAuth: ApiKeyAuth = {
+	name: `${CUSTOM_PROVIDER.label} API key`,
+	resolve: async () => {
+		const key = keyValue(CUSTOM_PROVIDER.envVar)?.trim();
+		return { auth: { apiKey: key || KEYLESS_PLACEHOLDER }, source: key ? CUSTOM_PROVIDER.envVar : "keyless" };
+	},
+};
+
+/** Map a discovered model to a pi-ai entry: image→input, reasoning→thinking
+ *  levels, context/maxTokens→limits. Resolution ladder (owner, 2026-10-27):
+ *  the user's pin wins, then the endpoint's own metadata, then the compiled
+ *  default — a local server that says nothing (or says 8k) can be corrected.
+ *  baseUrl is stamped per-model. */
+function toPiModel(
+	model: CustomModel,
+	baseUrl: string,
+	overrides: Record<string, CustomModelOverride>,
+): Model<Api> {
+	const pin = overrides[model.id];
+	return {
+		id: model.id,
+		name: model.id,
+		api: "openai-completions",
+		provider: CUSTOM_PROVIDER.id,
+		baseUrl,
+		// Pin wins; else detected from the endpoint's metadata (see
+		// detectReasoning). true makes pi-ai offer the standard levels and send
+		// reasoning_effort on the wire; no thinkingLevelMap → the default
+		// off/minimal/low/medium/high set.
+		reasoning: pin?.reasoning ?? Boolean(model.reasoning),
+		input: model.image ? ["text", "image"] : ["text"],
+		cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+		contextWindow: pin?.context ?? model.context ?? CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW,
+		maxTokens: pin?.maxTokens ?? model.maxTokens ?? CUSTOM_MODEL_DEFAULT_MAX_TOKENS,
+		type: "chat",
+	};
+}
+
+/** Build an OpenAI-compatible provider from parts. baseUrl must be normalized. */
+export function buildOpenAiCompatibleProvider(input: {
+	baseUrl: string;
+	models: readonly CustomModel[];
+	/** User pins by model id (see CustomModelOverride) — absent = none. */
+	overrides?: Record<string, CustomModelOverride>;
+}): Provider<Api> {
+	const overrides = input.overrides ?? {};
+	return createProvider<Api>({
+		id: CUSTOM_PROVIDER.id,
+		name: CUSTOM_PROVIDER.label,
+		baseUrl: input.baseUrl,
+		auth: { apiKey: customEndpointAuth },
+		models: input.models.map((m) => toPiModel(m, input.baseUrl, overrides)),
+		api: openAICompletionsApi(),
+	});
+}
+
+/** Re-sync the provider into piModels() (idempotent): usable → rebuild;
+ *  not usable → remove. Never throws. */
+export function syncCustomProvider(cp: CustomProviderSettings | undefined): void {
+	const models = piModels();
+	if (!customProviderUsable(cp)) {
+		models.deleteProvider(CUSTOM_PROVIDER.id);
+		return;
+	}
+	models.setProvider(
+		buildOpenAiCompatibleProvider({
+			baseUrl: normalizeBaseUrl(cp.baseUrl),
+			models: cp.models ?? [],
+			overrides: cp.overrides ?? {},
+		}),
+	);
+}
+
+/** Outcome of a model-discovery probe. `status` is the endpoint's HTTP status
+ *  when it answered at all, so callers can tell a rejected key from a missing
+ *  model list. */
+export type DiscoverResult =
+	| { ok: true; models: CustomModel[] }
+	| { ok: false; error: string; status?: number };
+
+/** Probe GET {baseUrl}/models for model ids. Scheme validated (http/https
+ *  only); keyless endpoints answer without a bearer. Non-2xx or unparseable
+ *  body → honest error, never a silent empty list. */
+export async function discoverModels(baseUrl: string, apiKey?: string): Promise<DiscoverResult> {
+	const base = normalizeBaseUrl(baseUrl);
+	if (!base) return { ok: false, error: "Base URL must be a valid http(s) URL" };
+	const key = apiKey?.trim() || keyValue(CUSTOM_PROVIDER.envVar)?.trim();
+	const controller = new AbortController();
+	const timer = setTimeout(() => controller.abort(), 15_000);
+	try {
+		const res = await fetch(`${base}/models`, {
+			headers: key ? { authorization: `Bearer ${key}` } : {},
+			signal: controller.signal,
+		});
+		if (!res.ok) return { ok: false, error: `Endpoint returned ${res.status} ${res.statusText}`, status: res.status };
+		const body = (await res.json().catch(() => null)) as unknown;
+		const list = extractModels(body);
+		if (list === null) return { ok: false, error: "Endpoint response was not a model list" };
+		return { ok: true, models: list };
+	} catch (err) {
+		const msg = err instanceof Error ? (err.name === "AbortError" ? "Endpoint timed out" : err.message) : "Request failed";
+		return { ok: false, error: msg };
+	} finally {
+		clearTimeout(timer);
+	}
+}
+
+/** The connect's model list: what the endpoint advertises, plus every typed id
+ *  it does not advertise (at default limits, so the pins can correct them).
+ *  Discovered metadata always wins over a typed id of the same name. */
+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 {
+	if (Array.isArray(body)) return body;
+	if (isRecord(body)) {
+		if (Array.isArray(body.data)) return body.data;
+		if (Array.isArray(body.models)) return body.models;
+	}
+	return null;
+}
+
+/** Does a /models row advertise image input? Scans the common modality/
+ *  capability fields; absent or unrecognized → false (text-only). */
+function detectImage(row: Record<string, unknown>): boolean {
+	const architecture = isRecord(row.architecture) ? row.architecture : undefined;
+	const candidates = [
+		architecture?.input_modalities,
+		row.input_modalities,
+		row.modalities,
+		row.supported_modalities,
+		row.capabilities,
+	];
+	for (const c of candidates) {
+		if (Array.isArray(c) && c.some((v) => typeof v === "string" && /image|vision/i.test(v))) return true;
+	}
+	return false;
+}
+
+/** Does a /models row advertise reasoning? Metadata only — no name guessing,
+ *  because a false positive sends reasoning_effort an endpoint will reject.
+ *  Trusted signals: an explicit boolean (reasoning / supports_reasoning /
+ *  thinking) or a reasoning token in the capability/parameter lists servers
+ *  publish (vLLM + OpenRouter's supported_parameters, capabilities, tags).
+ *  Absent or unrecognized → false (thinking stays "off"). */
+function detectReasoning(row: Record<string, unknown>): boolean {
+	for (const key of ["reasoning", "supports_reasoning", "thinking"] as const) {
+		if (row[key] === true) return true;
+	}
+	const architecture = isRecord(row.architecture) ? row.architecture : undefined;
+	const candidates = [row.supported_parameters, row.capabilities, row.tags, architecture?.output_modalities];
+	return candidates.some(
+		(list) =>
+			Array.isArray(list) &&
+			list.some((v) => typeof v === "string" && (/reasoning/i.test(v) || v.toLowerCase() === "thinking")),
+	);
+}
+
+/** First positive integer among `keys` on a row (endpoints name limits
+ *  inconsistently). */
+function firstPositive(row: Record<string, unknown>, keys: readonly string[]): number | undefined {
+	for (const key of keys) {
+		const value = row[key];
+		if (typeof value === "number" && Number.isInteger(value) && value > 0) return value;
+	}
+	return undefined;
+}
+
+// Field names seen in the wild for each limit (first present wins).
+const CONTEXT_KEYS = ["max_input_tokens", "context_length", "context_window", "max_context", "n_ctx", "max_seq_len", "max_position_embeddings"] as const;
+const MAX_TOKEN_KEYS = ["max_output_tokens"] as const;
+
+/** Pull models from a list response (objects with `id` or bare strings), each
+ *  with detected image + token limits. Null if the shape is unrecognized. */
+function extractModels(body: unknown): CustomModel[] | null {
+	const rows = modelRows(body);
+	if (rows === null) return null;
+	const byId = new Map<string, CustomModel>();
+	for (const row of rows) {
+		if (typeof row === "string") {
+			if (row.trim()) byId.set(row, { id: row });
+			continue;
+		}
+		if (isRecord(row) && typeof row.id === "string" && row.id.trim()) {
+			const model: CustomModel = { id: row.id };
+			if (detectImage(row)) model.image = true;
+			if (detectReasoning(row)) model.reasoning = true;
+			const context = firstPositive(row, CONTEXT_KEYS);
+			if (context) model.context = context;
+			const maxTokens = firstPositive(row, MAX_TOKEN_KEYS);
+			if (maxTokens) model.maxTokens = maxTokens;
+			byId.set(row.id, model);
+		}
+	}
+	return [...byId.values()].sort((a, b) => a.id.localeCompare(b.id));
+}
diff --git a/src/server/index.ts b/src/server/index.ts
index 0c3b002..9f24424 100644
--- a/src/server/index.ts
+++ b/src/server/index.ts
@@ -46,3 +46,6 @@ export * from "./model-catalog.ts";
 export { subscriptionControlsResponse, subscriptionBrowserResponse } from "./web-subscription-http.ts";
 export { sessionCost } from "./pricing.ts";
 export { claudeCodeInstallationResponse } from "./claude-code.ts";
+// The custom endpoint module (registers into piModels() + probes for models).
+// No import side effects; the boot sync lives in stores.ts.
+export * from "./custom-provider.ts";
diff --git a/src/server/keys.ts b/src/server/keys.ts
index 2151e49..46b2be3 100644
--- a/src/server/keys.ts
+++ b/src/server/keys.ts
@@ -43,6 +43,7 @@ import {
 	AUTH_KEYS,
 	AUTH_PROVIDER_KEYS,
 	AUTH_PROVIDER_ENV_VARS,
+	CUSTOM_PROVIDER,
 	type AuthKeyInfo,
 	type AuthKeyStatus,
 	genericProviderKeyGuard,
@@ -62,10 +63,10 @@ import { CLAUDE_CODE_PROVIDER } from "../agent/claude-code/constants.ts";
 // without importing this store-backed module into the agent layer.
 import { authEnvRecord as boot } from "../core/auth-env.ts";
 
-/** Is `id` a WRITABLE key name — curated catalog or model-provider env
- *  var (provider-keys interlude: PUT/DELETE accept both). */
+/** Is `id` a WRITABLE key name — curated catalog, model-provider env var, or
+ *  the custom endpoint's reserved key (writable through the same seam). */
 export function isWritableAuthKey(id: string): boolean {
-	return isKnownAuthKey(id) || isProviderEnvVar(id);
+	return isKnownAuthKey(id) || isProviderEnvVar(id) || id === CUSTOM_PROVIDER.envVar;
 }
 
 /** The settings page's provider dropdown: every pi-ai provider that takes
@@ -209,7 +210,10 @@ export function providerKeyPresent(provider: string): boolean {
  * reports shadowedByEnv so the page can explain it).
  */
 export function saveKey(id: string, value: string): { ok: true; status: AuthKeyStatus } | { ok: false; error: string } {
-	const shape = isProviderEnvVar(id) ? genericProviderKeyGuard(id, value) : validateKeyShape(id, value);
+	const shape =
+		isProviderEnvVar(id) || id === CUSTOM_PROVIDER.envVar
+			? genericProviderKeyGuard(id, value)
+			: validateKeyShape(id, value);
 	if (!shape.ok) return { ok: false, error: shape.error };
 	const trimmed = value.trim();
 	authStore.setAuthVar(id, trimmed);
diff --git a/src/server/model-catalog.ts b/src/server/model-catalog.ts
index e585150..fa24801 100644
--- a/src/server/model-catalog.ts
+++ b/src/server/model-catalog.ts
@@ -49,10 +49,17 @@ import type {
 	SlotPins,
 } from "../core/contracts/models.ts";
 import type { EffectiveModelSpec, EffectiveSlot } from "../core/settings-resolution.ts";
-import { AUTH_PROVIDER_KEYS } from "../core/auth-keys.ts";
+import { AUTH_PROVIDER_KEYS, CUSTOM_PROVIDER } from "../core/auth-keys.ts";
 import { claudeCodeAvailable } from "./claude-code-config.ts";
 import { CLAUDE_CODE_PROVIDER } from "../agent/claude-code/constants.ts";
-import { BACKGROUND_MODEL_ROLES, MODEL_SLOTS, type BackgroundModelRole, type ModelSlotName, type ModelsSettings } from "../core/settings.ts";
+import {
+	BACKGROUND_MODEL_ROLES,
+	MODEL_SLOTS,
+	customProviderUsable,
+	type BackgroundModelRole,
+	type ModelSlotName,
+	type ModelsSettings,
+} from "../core/settings.ts";
 
 /** The picker's client-safe model entry (contract: core/contracts/models.ts). */
 export type ModelDto = ModelCatalogEntry;
@@ -149,6 +156,11 @@ export function catalogProviders(): CatalogProvider[] {
 		{ id: CLAUDE_CODE_PROVIDER, envVar: "", keyPresent: claudeCodeAvailable() },
 		...NATIVE_SUBSCRIPTIONS.map((p) => ({ id: p.logicalId, envVar: "", keyPresent: nativeSubscriptionConnected(p.providerId) })),
 		...customProviderRows(),
+		// The custom endpoint: a row only when usable (base URL set). keyPresent
+		// reflects usability, not key presence (keyless local servers are allowed).
+		...(customProviderUsable(effectiveSettings().customProvider)
+			? [{ id: CUSTOM_PROVIDER.id, envVar: CUSTOM_PROVIDER.envVar, keyPresent: true }]
+			: []),
 	]).sort((a, b) => a.id.localeCompare(b.id));
 }
 
diff --git a/src/server/settings-body.ts b/src/server/settings-body.ts
index 81ae0f2..faad497 100644
--- a/src/server/settings-body.ts
+++ b/src/server/settings-body.ts
@@ -18,13 +18,14 @@ import type {
 	AppearanceSettings,
 	BackgroundModelRole,
 	CompactionSettings,
+	CustomModelOverride,
 	GeneralSettings,
 	DictationSettings,
 	GraphSettings,
 	ModelsSettings,
 	RoleModelOverride,
 } from "../core/settings.ts";
-import { BACKGROUND_MODEL_ROLES, COMPACTION_THRESHOLD_FLOOR, EXTRACTION_CHUNK_TOKENS_FLOOR, MODEL_SLOTS } from "../core/settings.ts";
+import { BACKGROUND_MODEL_ROLES, COMPACTION_THRESHOLD_FLOOR, CUSTOM_MODEL_PIN_FLOOR, EXTRACTION_CHUNK_TOKENS_FLOOR, MODEL_SLOTS } from "../core/settings.ts";
 import { WRITABLE_TOOL_KEYS } from "../core/pending.ts";
 import { isDictationLanguage } from "../core/dictation.ts";
 
@@ -395,8 +396,47 @@ export function parseDictationSettingsBody(body: unknown): SettingsBodyResult<Di
 	return { ok: true, settings: { language: raw.language } };
 }
 
-/** The section→parser map for PUT /api/settings/[section] (the route also
- *  carries the special prompts sub-resource). */
+/** The custom endpoint's per-model pins (PATCH /api/custom-provider): the
+ *  whole desired map, replace-whole like every section. Strict write side — a
+ *  token count must be a whole number at or above the floor (the read side
+ *  clamps, this rejects — the compaction discipline). `reasoning` is the
+ *  tri-state pin: true forces thinking on, false forces it off. */
+export function parseCustomModelOverridesBody(
+	body: unknown,
+): SettingsBodyResult<Record<string, CustomModelOverride>> {
+	const raw = asRecord(body);
+	if (!raw) return { ok: false, error: "Invalid JSON body" };
+	const map = asRecord(raw.overrides);
+	if (!map) return { ok: false, error: "overrides must be a { modelId: { context?, maxTokens?, reasoning? } } map" };
+	const out: Record<string, CustomModelOverride> = {};
+	for (const [key, value] of Object.entries(map)) {
+		const id = key.trim();
+		if (!id) return { ok: false, error: "override keys must be non-empty model ids" };
+		const entry = asRecord(value);
+		if (!entry) return { ok: false, error: `override for ${id} must be an object` };
+		const pin: CustomModelOverride = {};
+		for (const field of ["context", "maxTokens"] as const) {
+			const v = entry[field];
+			if (v === undefined) continue;
+			if (typeof v !== "number" || !Number.isInteger(v) || v < CUSTOM_MODEL_PIN_FLOOR) {
+				return {
+					ok: false,
+					error: `${field} for ${id} must be a whole number of tokens at least ${CUSTOM_MODEL_PIN_FLOOR}`,
+				};
+			}
+			pin[field] = v;
+		}
+		if (entry.reasoning !== undefined) {
+			if (typeof entry.reasoning !== "boolean") return { ok: false, error: `reasoning for ${id} must be true or false` };
+			pin.reasoning = entry.reasoning;
+		}
+		out[id] = pin;
+	}
+	return { ok: true, settings: out };
+}
+
+/** The section→parser map for PUT /api/settings/[section]. The custom endpoint
+ *  is NOT a section — it connects via POST /api/custom-provider. */
 export const SETTINGS_SECTIONS = {
 	general: parseGeneralSettingsBody,
 	chat: parseSettingsBody,
diff --git a/src/server/stores.ts b/src/server/stores.ts
index c63f546..27e6c3e 100644
--- a/src/server/stores.ts
+++ b/src/server/stores.ts
@@ -11,6 +11,7 @@ import { graphStore } from "../store/graph.ts";
 import { jobStore } from "../store/jobs.ts";
 import { settingsStore } from "../store/settings.ts";
 import { resolveSettings, type EffectiveSettings } from "../core/settings-resolution.ts";
+import { syncCustomProvider } from "./custom-provider.ts";
 /** The wired adapters. Satisfies core/graph.ts's GraphDeps structurally. */
 export const stores = {
 	chatStore,
@@ -32,3 +33,7 @@ export type Stores = typeof stores;
 export function effectiveSettings(): EffectiveSettings {
 	return resolveSettings(settingsStore.readSettings());
 }
+
+// Boot: register the custom endpoint (when configured) into piModels(); the
+// POST /api/custom-provider route re-syncs after every connect.
+syncCustomProvider(effectiveSettings().customProvider);
diff --git a/tests/custom-endpoint.test.ts b/tests/custom-endpoint.test.ts
new file mode 100644
index 0000000..d477b79
--- /dev/null
+++ b/tests/custom-endpoint.test.ts
@@ -0,0 +1,393 @@
+/**
+ * Tests for the custom OpenAI-compatible endpoint (custom-endpoint wave).
+ * Covers the pure core (normalizeBaseUrl, customProviderUsable, the sanitizer,
+ * resolution), the deep server module (provider build + live sync + model
+ * discovery incl. image-modality, reasoning detection and the per-model user
+ * pins), the pins' strict write-side parser, and the catalog federation row.
+ * No network: the discovery probe runs against a stubbed fetch.
+ */
+
+import assert from "node:assert/strict";
+import { after, describe, it } from "node:test";
+import {
+	CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW,
+	CUSTOM_MODEL_DEFAULT_MAX_TOKENS,
+	CUSTOM_MODEL_PIN_FLOOR,
+	customProviderUsable,
+	normalizeBaseUrl,
+	parseModelIds,
+	sanitizeCustomModelOverrides,
+	sanitizeUserSettings,
+} from "../src/core/settings.ts";
+import { resolveSettings } from "../src/core/settings-resolution.ts";
+import { parseCustomModelOverridesBody } from "../src/server/settings-body.ts";
+import { CUSTOM_PROVIDER } from "../src/core/auth-keys.ts";
+import {
+	buildOpenAiCompatibleProvider,
+	discoverModels,
+	mergeManualModels,
+	syncCustomProvider,
+} from "../src/server/custom-provider.ts";
+import { piModels } from "../src/agent/models.ts";
+import { getSupportedThinkingLevels } from "@earendil-works/pi-ai";
+
+// ─── normalizeBaseUrl ────────────────────────────────────────────────────────
+describe("normalizeBaseUrl", () => {
+	it("drops trailing slashes and keeps the path", () => {
+		assert.equal(normalizeBaseUrl("https://host:8000/v1/"), "https://host:8000/v1");
+		assert.equal(normalizeBaseUrl("  https://host/v1  "), "https://host/v1");
+		assert.equal(normalizeBaseUrl("http://localhost:11434"), "http://localhost:11434");
+	});
+	it("rejects non-http(s) schemes and junk with empty string", () => {
+		assert.equal(normalizeBaseUrl("file:///etc/passwd"), "");
+		assert.equal(normalizeBaseUrl("not a url"), "");
+		assert.equal(normalizeBaseUrl(""), "");
+	});
+});
+
+// ─── customProviderUsable ────────────────────────────────────────────────────
+describe("customProviderUsable", () => {
+	it("is true exactly when a base URL is set (the key is optional)", () => {
+		assert.equal(customProviderUsable({ baseUrl: "https://h/v1" }), true);
+		assert.equal(customProviderUsable({ baseUrl: "" }), false);
+		assert.equal(customProviderUsable({}), false);
+		assert.equal(customProviderUsable(undefined), false);
+	});
+});
+
+// ─── sanitizer ───────────────────────────────────────────────────────────────
+describe("sanitizeUserSettings — customProvider", () => {
+	it("normalizes the base URL and cleans the model list (trim, dedupe, image flag)", () => {
+		const out = sanitizeUserSettings({
+			customProvider: {
+				baseUrl: "https://host:8000/v1/",
+				models: [
+					{ id: " llama-3 " }, // trims id; image absent
+					{ id: "gpt", image: true },
+					{ id: "gpt", image: false }, // dup id wins (last) → image dropped
+					{ id: "" }, // dropped: no usable id
+					"not-an-object", // dropped
+				],
+			},
+		});
+		const cp = out?.customProvider;
+		assert.equal(cp?.baseUrl, "https://host:8000/v1");
+		assert.deepEqual(cp?.models, [{ id: "llama-3" }, { id: "gpt" }]);
+	});
+	it("keeps image:true and drops a non-array models list / invalid base URL", () => {
+		const out = sanitizeUserSettings({ customProvider: { baseUrl: "ftp://x", models: "nope" } });
+		assert.equal(out?.customProvider?.baseUrl, undefined);
+		assert.equal(out?.customProvider?.models, undefined);
+	});
+	it("keeps reasoning:true and drops a non-true reasoning flag", () => {
+		const out = sanitizeUserSettings({
+			customProvider: {
+				baseUrl: "https://h/v1",
+				models: [{ id: "thinker", reasoning: true }, { id: "plain", reasoning: "yes" }],
+			},
+		});
+		assert.deepEqual(out?.customProvider?.models, [{ id: "thinker", reasoning: true }, { id: "plain" }]);
+	});
+});
+
+// ─── per-model pins: the read side + THE prune law ───────────────────────────
+describe("sanitizeUserSettings / sanitizeCustomModelOverrides — pins", () => {
+	it("keeps well-formed pins, clamps token counts up to the floor, keeps reasoning:false", () => {
+		const out = sanitizeUserSettings({
+			customProvider: {
+				baseUrl: "https://h/v1",
+				overrides: {
+					llama: { context: 131072, maxTokens: 8192, reasoning: true },
+					qwen: { context: 10 }, // under the floor → clamped up (clamp-never-reject on read)
+					quiet: { reasoning: false }, // a real pin, not an absent one
+					junk: { context: "big", maxTokens: -1, reasoning: "yes" }, // every field junk
+					" ": { context: 4096 }, // no usable id
+					nope: "not-an-object",
+				},
+			},
+		});
+		assert.deepEqual(out?.customProvider?.overrides, {
+			llama: { context: 131072, maxTokens: 8192, reasoning: true },
+			qwen: { context: CUSTOM_MODEL_PIN_FLOOR },
+			quiet: { reasoning: false },
+		});
+	});
+	it("prunes pins for models the endpoint no longer advertises — the single prune law", () => {
+		const pins = { a: { context: 32768 }, b: { context: 32768 } };
+		assert.deepEqual(Object.keys(sanitizeCustomModelOverrides(pins, ["a"])), ["a"]);
+		assert.deepEqual(
+			Object.keys(sanitizeCustomModelOverrides(pins)),
+			["a", "b"],
+			"no liveIds → no prune (that is the routes' call, not the record sanitizer's)",
+		);
+		assert.deepEqual(sanitizeCustomModelOverrides("nope"), {}, "a non-object map resolves empty");
+	});
+	it("drops an invalid overrides section from the record entirely", () => {
+		const out = sanitizeUserSettings({ customProvider: { baseUrl: "https://h/v1", overrides: "nope" } });
+		assert.equal(out?.customProvider?.overrides, undefined);
+	});
+});
+
+// ─── pins: the strict write side (PATCH) ──────────────────────────────────
+describe("parseCustomModelOverridesBody — the strict write side", () => {
+	it("accepts whole counts at or above the floor and the tri-state reasoning pin", () => {
+		const r = parseCustomModelOverridesBody({
+			overrides: {
+				a: { context: CUSTOM_MODEL_PIN_FLOOR, reasoning: false },
+				b: { maxTokens: 8192 },
+				c: {}, // an empty pin is legal — the sanitizer drops it on write
+			},
+		});
+		assert.ok(r.ok);
+		assert.deepEqual(r.settings, {
+			a: { context: CUSTOM_MODEL_PIN_FLOOR, reasoning: false },
+			b: { maxTokens: 8192 },
+			c: {},
+		});
+	});
+	it("rejects a count under the floor, naming the floor", () => {
+		const r = parseCustomModelOverridesBody({ overrides: { a: { context: CUSTOM_MODEL_PIN_FLOOR - 1 } } });
+		assert.equal(r.ok, false);
+		if (!r.ok) assert.ok(r.error.includes(String(CUSTOM_MODEL_PIN_FLOOR)), r.error);
+	});
+	it("rejects a fractional count, a non-boolean reasoning, and a missing overrides map", () => {
+		assert.equal(parseCustomModelOverridesBody({ overrides: { a: { context: 4096.5 } } }).ok, false);
+		assert.equal(parseCustomModelOverridesBody({ overrides: { a: { reasoning: "on" } } }).ok, false);
+		assert.equal(parseCustomModelOverridesBody({ overrides: { a: "nope" } }).ok, false);
+		assert.equal(parseCustomModelOverridesBody({}).ok, false);
+		assert.equal(parseCustomModelOverridesBody(null).ok, false);
+	});
+});
+
+// ─── resolution ──────────────────────────────────────────────────────────
+describe("resolveSettings — customProvider", () => {
+	it("resolves an absent section to concrete defaults", () => {
+		assert.deepEqual(resolveSettings(null).customProvider, { baseUrl: "", models: [], overrides: {}, manualModels: [] });
+	});
+	it("carries stored pins through to the concrete view", () => {
+		const resolved = resolveSettings({
+			version: 1,
+			customProvider: { baseUrl: "http://h/v1", models: [{ id: "a" }], overrides: { a: { context: 32768 } } },
+		});
+		assert.deepEqual(resolved.customProvider.overrides, { a: { context: 32768 } });
+	});
+	it("carries stored manual model ids through to the concrete view", () => {
+		const resolved = resolveSettings({
+			version: 1,
+			customProvider: { baseUrl: "http://h/v1", models: [{ id: "a" }], manualModels: ["a"] },
+		});
+		assert.deepEqual(resolved.customProvider.manualModels, ["a"]);
+	});
+});
+
+describe("manual model ids", () => {
+	it("parseModelIds splits a typed list on commas and whitespace, trims and dedupes", () => {
+		assert.deepEqual(parseModelIds(" doubao-seed-2.1-pro, kimi-k3.1-pro\nqwen/qwen3-max ,, kimi-k3.1-pro "), [
+			"doubao-seed-2.1-pro",
+			"kimi-k3.1-pro",
+			"qwen/qwen3-max",
+		]);
+	});
+	it("parseModelIds accepts a string array and ignores non-strings and junk", () => {
+		assert.deepEqual(parseModelIds(["a", " b ", "", 3, null, "a"]), ["a", "b"]);
+		assert.deepEqual(parseModelIds(undefined), []);
+		assert.deepEqual(parseModelIds({ id: "a" }), []);
+	});
+	it("the sanitizer keeps a clean manual list and drops an empty one", () => {
+		const kept = sanitizeUserSettings({ version: 1, customProvider: { baseUrl: "http://h/v1", manualModels: [" a ", "a", "b"] } });
+		assert.deepEqual(kept?.customProvider?.manualModels, ["a", "b"]);
+		const dropped = sanitizeUserSettings({ version: 1, customProvider: { baseUrl: "http://h/v1", manualModels: [] } });
+		assert.equal(dropped?.customProvider?.manualModels, undefined);
+	});
+	it("mergeManualModels adds typed ids with defaults and never replaces discovered metadata", () => {
+		const merged = mergeManualModels([{ id: "b", image: true, context: 65536 }], ["c", "b", "a"]);
+		assert.deepEqual(merged, [{ id: "a" }, { id: "b", image: true, context: 65536 }, { id: "c" }]);
+	});
+	it("mergeManualModels alone builds the list when discovery found nothing", () => {
+		assert.deepEqual(mergeManualModels([], ["x"]), [{ id: "x" }]);
+	});
+});
+
+// ─── provider build + live sync ──────────────────────────────────────────────
+describe("buildOpenAiCompatibleProvider / syncCustomProvider", () => {
+	after(() => piModels().deleteProvider(CUSTOM_PROVIDER.id));
+
+	it("maps ids to defaults and marks image-capable models image-input", () => {
+		const provider = buildOpenAiCompatibleProvider({
+			baseUrl: "http://h/v1",
+			models: [{ id: "m1" }, { id: "m2", image: true }],
+		});
+		assert.equal(provider.id, CUSTOM_PROVIDER.id);
+		const [m1, m2] = provider.getModels();
+		assert.equal(m1!.name, "m1");
+		assert.equal(m1!.api, "openai-completions");
+		assert.equal(m1!.provider, CUSTOM_PROVIDER.id);
+		assert.equal(m1!.baseUrl, "http://h/v1");
+		assert.equal(m1!.contextWindow, CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW);
+		assert.equal(m1!.maxTokens, CUSTOM_MODEL_DEFAULT_MAX_TOKENS);
+		assert.deepEqual(m1!.input, ["text"]); // text-only by default
+		assert.deepEqual(m2!.input, ["text", "image"]); // image-capable → Vision-eligible
+		assert.equal(m1!.contextWindow, CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW); // no endpoint value → default
+		assert.equal(m1!.maxTokens, CUSTOM_MODEL_DEFAULT_MAX_TOKENS);
+	});
+
+	it("carries endpoint token limits when present", () => {
+		const provider = buildOpenAiCompatibleProvider({
+			baseUrl: "http://h/v1",
+			models: [{ id: "big", context: 196608, maxTokens: 393216 }],
+		});
+		const [big] = provider.getModels();
+		assert.equal(big!.contextWindow, 196608); // 192k from the endpoint
+		assert.equal(big!.maxTokens, 393216);
+	});
+
+	it("a user pin beats the endpoint, which beats the compiled default", () => {
+		const provider = buildOpenAiCompatibleProvider({
+			baseUrl: "http://h/v1",
+			models: [{ id: "pinned", context: 32768, maxTokens: 4096 }, { id: "detected", context: 65536 }, { id: "bare" }],
+			overrides: { pinned: { context: 131072, maxTokens: 16384 } },
+		});
+		const [pinned, detected, bare] = provider.getModels();
+		assert.equal(pinned!.contextWindow, 131072, "the pin wins over the endpoint's own number");
+		assert.equal(pinned!.maxTokens, 16384);
+		assert.equal(detected!.contextWindow, 65536, "no pin → the endpoint's value");
+		assert.equal(detected!.maxTokens, CUSTOM_MODEL_DEFAULT_MAX_TOKENS, "endpoint silent → the compiled default");
+		assert.equal(bare!.contextWindow, CUSTOM_MODEL_DEFAULT_CONTEXT_WINDOW);
+	});
+
+	it("the thinking pin is tri-state: false beats a detected-true endpoint, true beats silence", () => {
+		const provider = buildOpenAiCompatibleProvider({
+			baseUrl: "http://h/v1",
+			models: [{ id: "liar", reasoning: true }, { id: "silent" }],
+			overrides: { liar: { reasoning: false }, silent: { reasoning: true } },
+		});
+		const [liar, silent] = provider.getModels();
+		assert.equal(liar!.reasoning, false, "a server that advertises reasoning but rejects it can be pinned off");
+		assert.deepEqual(getSupportedThinkingLevels(liar!), ["off"]);
+		assert.equal(silent!.reasoning, true, "LM Studio publishes nothing; the user says otherwise");
+		assert.deepEqual(getSupportedThinkingLevels(silent!), ["off", "minimal", "low", "medium", "high"]);
+	});
+
+	it("gives a reasoning-capable model the standard thinking levels (others stay \"off\")", () => {
+		const provider = buildOpenAiCompatibleProvider({
+			baseUrl: "http://h/v1",
+			models: [{ id: "thinker", reasoning: true }, { id: "plain" }],
+		});
+		const [thinker, plain] = provider.getModels();
+		assert.equal(thinker!.reasoning, true);
+		// No thinkingLevelMap → pi-ai's default set, same as any reasoning model.
+		assert.deepEqual(getSupportedThinkingLevels(thinker!), ["off", "minimal", "low", "medium", "high"]);
+		assert.equal(plain!.reasoning, false);
+		assert.deepEqual(getSupportedThinkingLevels(plain!), ["off"]);
+	});
+
+	it("registers on a usable sync and removes when the base URL clears", () => {
+		syncCustomProvider({ baseUrl: "http://h/v1", models: [{ id: "live" }] });
+		assert.ok(piModels().getProvider(CUSTOM_PROVIDER.id), "provider registered");
+		assert.ok(piModels().getModel(CUSTOM_PROVIDER.id, "live"), "model resolvable");
+		syncCustomProvider({ baseUrl: "", models: [{ id: "live" }] });
+		assert.equal(piModels().getProvider(CUSTOM_PROVIDER.id), undefined, "provider removed");
+	});
+});
+
+// ─── discovery (stubbed fetch) ───────────────────────────────────────────────
+describe("discoverModels", () => {
+	const realFetch = globalThis.fetch;
+	after(() => {
+		globalThis.fetch = realFetch;
+	});
+
+	function stubFetch(handler: (url: string) => { status: number; body: unknown }) {
+		globalThis.fetch = (async (input: unknown) => {
+			const res = handler(String(input));
+			return new Response(JSON.stringify(res.body), { status: res.status });
+		}) as unknown as typeof fetch;
+	}
+
+	it("reads OpenAI {data:[{id}]} and Ollama {models:[{id}]} shapes", async () => {
+		stubFetch(() => ({ status: 200, body: { data: [{ id: "b" }, { id: "a" }] } }));
+		const openai = await discoverModels("http://h/v1");
+		assert.ok(openai.ok);
+		assert.deepEqual(openai.models, [{ id: "a" }, { id: "b" }]);
+		stubFetch(() => ({ status: 200, body: { models: [{ id: "x" }] } }));
+		const r = await discoverModels("http://h/v1");
+		assert.ok(r.ok && r.models.length === 1 && r.models[0]!.id === "x");
+	});
+	it("detects image capability from common modality fields", async () => {
+		stubFetch(() => ({
+			status: 200,
+			body: {
+				data: [
+					{ id: "vision-model", architecture: { input_modalities: ["text", "image"] } },
+					{ id: "cap-model", capabilities: ["completion", "vision"] },
+					{ id: "text-model", architecture: { input_modalities: ["text"] } },
+				],
+			},
+		}));
+		const r = await discoverModels("http://h/v1");
+		assert.ok(r.ok);
+		const byId = Object.fromEntries(r.models.map((m) => [m.id, Boolean(m.image)]));
+		assert.equal(byId["vision-model"], true);
+		assert.equal(byId["cap-model"], true);
+		assert.equal(byId["text-model"], false);
+	});
+	it("detects token limits from common metadata fields", async () => {
+		stubFetch(() => ({
+			status: 200,
+			body: {
+				data: [
+					{ id: "big", max_input_tokens: 196608, max_output_tokens: 393216 },
+					{ id: "ctx", context_length: 32768 },
+					{ id: "plain" },
+				],
+			},
+		}));
+		const r = await discoverModels("http://h/v1");
+		assert.ok(r.ok);
+		const byId = Object.fromEntries(r.models.map((m) => [m.id, m]));
+		assert.equal(byId["big"]!.context, 196608);
+		assert.equal(byId["big"]!.maxTokens, 393216);
+		assert.equal(byId["ctx"]!.context, 32768);
+		assert.equal(byId["ctx"]!.maxTokens, undefined);
+		assert.equal(byId["plain"]!.context, undefined);
+	});
+	it("detects reasoning from endpoint metadata only — never from the model name", async () => {
+		stubFetch(() => ({
+			status: 200,
+			body: {
+				data: [
+					{ id: "vllm-reasoner", supported_parameters: ["temperature", "reasoning", "reasoning_effort"] },
+					{ id: "bool-reasoner", reasoning: true },
+					{ id: "thinking-flag", thinking: true },
+					{ id: "cap-reasoner", capabilities: ["completion", "reasoning"] },
+					{ id: "deepseek-r1-distill" }, // a reasoning-sounding NAME, no metadata → stays off
+				],
+			},
+		}));
+		const r = await discoverModels("http://h/v1");
+		assert.ok(r.ok);
+		const byId = Object.fromEntries(r.models.map((m) => [m.id, Boolean(m.reasoning)]));
+		assert.equal(byId["vllm-reasoner"], true);
+		assert.equal(byId["bool-reasoner"], true);
+		assert.equal(byId["thinking-flag"], true);
+		assert.equal(byId["cap-reasoner"], true);
+		assert.equal(byId["deepseek-r1-distill"], false, "name guessing would risk sending reasoning_effort to a server that rejects it");
+	});
+
+	it("guards the scheme before any fetch", async () => {
+		let called = false;
+		globalThis.fetch = (async () => {
+			called = true;
+			return new Response("{}", { status: 200 });
+		}) as unknown as typeof fetch;
+		const r = await discoverModels("file:///etc/passwd");
+		assert.equal(r.ok, false);
+		assert.equal(called, false, "no fetch for a non-http scheme");
+	});
+	it("reports a non-2xx and an unparseable shape as honest errors", async () => {
+		stubFetch(() => ({ status: 500, body: {} }));
+		assert.equal((await discoverModels("http://h/v1")).ok, false);
+		stubFetch(() => ({ status: 200, body: { unexpected: true } }));
+		assert.equal((await discoverModels("http://h/v1")).ok, false);
+	});
+});
diff --git a/tests/custom-provider-route.test.ts b/tests/custom-provider-route.test.ts
new file mode 100644
index 0000000..6315ded
--- /dev/null
+++ b/tests/custom-provider-route.test.ts
@@ -0,0 +1,129 @@
+/**
+ * POST /api/custom-provider — the connect policy around manually typed model
+ * ids. Two rules earn a route test (the pure pieces live in
+ * custom-endpoint.test.ts):
+ *   1. Typed ids make a FAILED probe survivable, but never a rejected key.
+ *   2. A failed probe never shrinks the snapshot it already stored: that prune
+ *      would take the model metadata and the user's pins with it.
+ */
+import assert from "node:assert/strict";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import { after, before, describe, it } from "node:test";
+
+const dir = fs.mkdtempSync(path.join(os.tmpdir(), "lh-custom-route-"));
+process.env.LH_DATA_DIR = dir;
+process.env.LH_AUTH_FILE = path.join(dir, "auth.json");
+const SETTINGS_FILE = path.join(dir, "settings.json");
+
+const realFetch = globalThis.fetch;
+after(() => {
+	globalThis.fetch = realFetch;
+	fs.rmSync(dir, { recursive: true, force: true });
+	delete process.env.LH_DATA_DIR;
+	delete process.env.LH_AUTH_FILE;
+});
+
+type Route = typeof import("../app/api/custom-provider/route.ts");
+let route: Route;
+before(async () => {
+	route = await import("../app/api/custom-provider/route.ts");
+});
+
+const BASE = "http://h/v1";
+/** A connected endpoint with two discovered models, a pin on each, one typed id. */
+const CONNECTED = {
+	version: 1,
+	customProvider: {
+		baseUrl: BASE,
+		models: [{ id: "disc-1", context: 131072 }, { id: "disc-2" }],
+		overrides: { "disc-1": { context: 200000 }, "disc-2": { maxTokens: 8192 } },
+		manualModels: ["m1"],
+	},
+};
+
+function seed(record: unknown): void {
+	fs.writeFileSync(SETTINGS_FILE, JSON.stringify(record, null, "\t"), "utf-8");
+}
+
+function stored(): { customProvider?: { models?: { id: string }[]; overrides?: unknown; manualModels?: string[] } } {
+	return JSON.parse(fs.readFileSync(SETTINGS_FILE, "utf-8"));
+}
+
+function answerWith(status: number, statusText: string, body?: unknown): void {
+	globalThis.fetch = (async () => (body === undefined ? new Response("nope", { status, statusText }) : Response.json(body))) as typeof fetch;
+}
+
+function post(payload: unknown): Promise<Response> {
+	return route.POST(
+		new Request("http://localhost/api/custom-provider", {
+			method: "POST",
+			headers: { "content-type": "application/json" },
+			body: JSON.stringify(payload),
+		}),
+	);
+}
+
+describe("POST /api/custom-provider — typed ids and a failed probe", () => {
+	it("a transient failure keeps the stored models, their metadata, and their pins", async () => {
+		seed(CONNECTED);
+		answerWith(503, "Service Unavailable");
+
+		const res = await post({ baseUrl: BASE, manualModels: "m1" });
+		assert.equal(res.status, 200);
+
+		const cp = stored().customProvider;
+		assert.deepEqual(cp?.models?.map((m) => m.id), ["disc-1", "disc-2", "m1"]);
+		assert.deepEqual(cp?.models?.[0], { id: "disc-1", context: 131072 }, "detected metadata survives");
+		assert.deepEqual(cp?.overrides, CONNECTED.customProvider.overrides, "the prune must not fire on a failed probe");
+		assert.deepEqual(cp?.manualModels, ["m1"]);
+	});
+
+	it("a rejected key fails the connect even when ids are typed", async () => {
+		seed(CONNECTED);
+		answerWith(401, "Unauthorized");
+		const before = stored();
+
+		const res = await post({ baseUrl: BASE, key: "sk-abcdefghijk", manualModels: "m1" });
+		assert.equal(res.status, 502);
+		assert.deepEqual(stored(), before, "nothing is stored on an auth failure");
+	});
+
+	it("a new endpoint with no model list starts from the typed ids alone", async () => {
+		seed(CONNECTED);
+		answerWith(404, "Not Found");
+
+		const res = await post({ baseUrl: "http://other/v1", manualModels: "y, x" });
+		assert.equal(res.status, 200);
+
+		const cp = stored().customProvider;
+		assert.deepEqual(cp?.models?.map((m) => m.id), ["x", "y"], "the previous endpoint's models do not follow the URL");
+		assert.equal(cp?.overrides, undefined, "no pin survives a list the old pins do not belong to");
+		assert.deepEqual(cp?.manualModels, ["y", "x"], "the typed order is kept as typed");
+	});
+
+	it("no model list and no typed ids still refuses, with the hint", async () => {
+		answerWith(404, "Not Found");
+
+		const res = await post({ baseUrl: BASE });
+		assert.equal(res.status, 502);
+		const body = (await res.json()) as { error: string };
+		assert.match(body.error, /404/);
+		assert.match(body.error, /add model IDs manually/);
+	});
+
+	it("a working probe merges the typed ids and keeps discovered metadata", async () => {
+		seed(CONNECTED);
+		answerWith(200, "OK", { data: [{ id: "disc-1", context_length: 65536 }] });
+
+		const res = await post({ baseUrl: BASE, manualModels: "disc-1, m2" });
+		assert.equal(res.status, 200);
+
+		const cp = stored().customProvider;
+		assert.deepEqual(cp?.models?.map((m) => m.id), ["disc-1", "m2"]);
+		assert.deepEqual(cp?.models?.[0], { id: "disc-1", context: 65536 }, "discovery is not replaced by a bare typed id");
+		assert.deepEqual(cp?.overrides, { "disc-1": { context: 200000 } }, "pins follow the ids this connect offers");
+		assert.deepEqual(cp?.manualModels, ["disc-1", "m2"]);
+	});
+});
diff --git a/tests/settings-body.test.ts b/tests/settings-body.test.ts
index 7c7df16..1dcb0da 100644
--- a/tests/settings-body.test.ts
+++ b/tests/settings-body.test.ts
@@ -236,7 +236,9 @@ describe("parseCompactionSettingsBody (owner round 14)", () => {
 describe("SETTINGS_SECTIONS (the route's section map)", () => {
 	it("maps exactly the eight record sections", () => {
 		// compaction joined (owner round 14): its own section PUT — the
-		// threshold is engine behavior, not an agent-section key.
+		// threshold is engine behavior, not an agent-section key. The custom
+		// endpoint is NOT a section: it is one more provider in the Keys list,
+		// connected through POST /api/custom-provider.
 		assert.deepEqual(
 			Object.keys(SETTINGS_SECTIONS),
 			["general", "chat", "agent", "appearance", "graph", "compaction", "models", "dictation", "claudeCode"],
diff --git a/tests/setup-dialog-interaction.test.tsx b/tests/setup-dialog-interaction.test.tsx
index 186cec6..4e3b8fb 100644
--- a/tests/setup-dialog-interaction.test.tsx
+++ b/tests/setup-dialog-interaction.test.tsx
@@ -172,10 +172,15 @@ describe("setup polish interactions", () => {
 		assert.equal(closed, 0);
 	});
 
-	it("the empty vision list gives the approved next action without an em dash", 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"]'));
-		assert.ok(element('[data-testid="setup-menu-vision"]').textContent?.includes("No image-capable models. Add a provider key with access to a vision model."));
+		// 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 () => {