milestone 20: declarative configuration for iac

web/src/features/blocklists/BlocklistForm.test.tsx

@@ -10,7 +10,9 @@ test("swallowMutationError drops an ApiError and rethrows anything else", () =>
 
 test("a rejected submit leaves the typed values in place; a resolved one clears them", async () => {
 	const rejecting = vi.fn(() => Promise.reject(new ApiError(400, "bad url")));
-	const { rerender } = render(<BlocklistForm busy={false} error={null} onSubmit={rejecting} onCancel={undefined} />);
+	const { rerender } = render(
+		<BlocklistForm busy={false} readOnly={false} error={null} onSubmit={rejecting} onCancel={undefined} />,
+	);
 	const url = screen.getByLabelText("URL") as HTMLInputElement;
 	const name = screen.getByLabelText("Name") as HTMLInputElement;
 	fireEvent.change(url, { target: { value: "https://example.com/list.txt" } });
@@ -22,7 +24,7 @@ test("a rejected submit leaves the typed values in place; a resolved one clears
 	expect(name.value).toBe("Example");
 
 	const resolving = vi.fn(() => Promise.resolve());
-	rerender(<BlocklistForm busy={false} error={null} onSubmit={resolving} onCancel={undefined} />);
+	rerender(<BlocklistForm busy={false} readOnly={false} error={null} onSubmit={resolving} onCancel={undefined} />);
 	fireEvent.click(screen.getByRole("button", { name: "Add source" }));
 	await waitFor(() => expect(url.value).toBe(""));
 	expect(name.value).toBe("");

web/src/features/blocklists/BlocklistForm.tsx

@@ -3,6 +3,7 @@ import { ApiError } from "@/lib/api";
 import InlineError from "@/lib/InlineError";
 import type { Blocklist, BlocklistInput } from "@/lib/types";
 import { buttonClass, focusRing, inputClass, primaryButtonClass } from "@/ui/classes";
+import { READ_ONLY_HINT } from "@/features/settings/authority";
 
 /**
  * Drops the rejection the page already renders inline below the form. Anything
@@ -17,12 +18,14 @@ export function swallowMutationError(error: unknown): void {
 interface BlocklistFormProps {
 	initial?: Blocklist;
 	busy: boolean;
+	/** File authority: the server answers 403, so the submit stays down. */
+	readOnly: boolean;
 	error: Error | null;
 	onSubmit: (input: BlocklistInput) => Promise<void>;
 	onCancel?: () => void;
 }
 
-export default function BlocklistForm({ initial, busy, error, onSubmit, onCancel }: BlocklistFormProps) {
+export default function BlocklistForm({ initial, busy, readOnly, error, onSubmit, onCancel }: BlocklistFormProps) {
 	const [url, setUrl] = useState(initial?.url ?? "");
 	const [name, setName] = useState(initial?.name ?? "");
 	const [enabled, setEnabled] = useState(initial?.enabled ?? true);
@@ -81,7 +84,12 @@ export default function BlocklistForm({ initial, busy, error, onSubmit, onCancel
 				Enabled
 			</label>
 			<div className="flex items-center gap-2">
-				<button type="submit" disabled={busy} className={primaryButtonClass}>
+				<button
+					type="submit"
+					disabled={busy || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={primaryButtonClass}
+				>
 					{initial === undefined ? "Add source" : "Save changes"}
 				</button>
 				{onCancel !== undefined && (

web/src/features/blocklists/BlocklistsPage.tsx

@@ -22,6 +22,7 @@ import {
 	tdClass,
 	thClass,
 } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 export default function BlocklistsPage() {
 	const queryClient = useQueryClient();
@@ -36,6 +37,9 @@ export default function BlocklistsPage() {
 
 	const sources = useRefreshStatus();
 	const namesById = new Map(blocklists.map((b) => [b.id, b.name]));
+	// The refresh below re-fetches the sources the config already declares, so
+	// it stays live in file mode; every other control here writes config.
+	const readOnly = useReadOnlyConfig();
 
 	async function submitForm(input: BlocklistInput) {
 		if (editing === null) {
@@ -122,7 +126,8 @@ export default function BlocklistsPage() {
 											type="checkbox"
 											aria-label={`${b.name} enabled`}
 											checked={b.enabled}
-											disabled={toggle.isPending}
+											disabled={toggle.isPending || readOnly}
+											title={readOnly ? READ_ONLY_HINT : undefined}
 											onChange={() => toggleEnabled(b)}
 											className={focusRing}
 										/>
@@ -138,14 +143,17 @@ export default function BlocklistsPage() {
 											<button
 												type="button"
 												onClick={() => setEditing(b)}
-												className={linkButtonClass}
+												disabled={readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
+												className={`${linkButtonClass} disabled:opacity-50`}
 											>
 												Edit
 											</button>
 											<button
 												type="button"
 												onClick={() => deleteBlocklist(b)}
-												disabled={remove.isPending}
+												disabled={remove.isPending || readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
 												className={dangerLinkButtonClass}
 											>
 												Delete
@@ -164,6 +172,7 @@ export default function BlocklistsPage() {
 				key={editing?.id ?? "add"}
 				initial={editing ?? undefined}
 				busy={editing === null ? create.isPending : save.isPending}
+				readOnly={readOnly}
 				error={formError}
 				onSubmit={submitForm}
 				onCancel={editing === null ? undefined : () => setEditing(null)}

web/src/features/clients/ClientEditDialog.tsx

@@ -4,6 +4,7 @@ import { clientUpdateMutation } from "@/lib/queries";
 import type { Client, Group } from "@/lib/types";
 import InlineError from "@/lib/InlineError";
 import { buttonClass, primaryButtonClass, smallInputClass } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 interface Props {
 	client: Client;
@@ -18,6 +19,7 @@ export default function ClientEditDialog({ client, groups, onClose }: Props) {
 	const mutation = useMutation(clientUpdateMutation(queryClient));
 	const [name, setName] = useState(client.name);
 	const [groupId, setGroupId] = useState(client.group_id);
+	const readOnly = useReadOnlyConfig();
 
 	return (
 		<div className="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4">
@@ -67,7 +69,12 @@ export default function ClientEditDialog({ client, groups, onClose }: Props) {
 						<button type="button" onClick={onClose} className={buttonClass}>
 							Cancel
 						</button>
-						<button type="submit" disabled={mutation.isPending} className={primaryButtonClass}>
+						<button
+							type="submit"
+							disabled={mutation.isPending || readOnly}
+							title={readOnly ? READ_ONLY_HINT : undefined}
+							className={primaryButtonClass}
+						>
 							Save
 						</button>
 					</div>

web/src/features/clients/ClientsPage.tsx

@@ -7,9 +7,17 @@ import ClientEditDialog from "./ClientEditDialog";
 import PrefixesEditor from "./PrefixesEditor";
 import InlineError from "@/lib/InlineError";
 import { smallButtonClass, tableWrapClass } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 const cellClass = "px-3 py-2";
 
+/**
+ * Deleting an observed row discards runtime state the file never declared, so
+ * it stays live under file authority; deleting a hand-edited row contradicts
+ * the file and is the one client DELETE the server answers 403 (ruling 7).
+ */
+const DECLARED_CLIENT_NOTE = "This client is declared in the configuration file; remove it there and restart.";
+
 export default function ClientsPage() {
 	const { data: clients } = useSuspenseQuery(clientsQuery());
 	const { data: prefixes } = useSuspenseQuery(clientPrefixesQuery());
@@ -18,6 +26,7 @@ export default function ClientsPage() {
 	const deleteMutation = useMutation(clientDeleteMutation(queryClient));
 	const [editing, setEditing] = useState<Client | null>(null);
 	const [confirmingId, setConfirmingId] = useState<number | null>(null);
+	const readOnly = useReadOnlyConfig();
 
 	return (
 		<section>
@@ -86,14 +95,22 @@ export default function ClientsPage() {
 												<button
 													type="button"
 													onClick={() => setEditing(client)}
-													className={smallButtonClass}
+													disabled={readOnly}
+													title={readOnly ? READ_ONLY_HINT : undefined}
+													className={`${smallButtonClass} disabled:opacity-50`}
 												>
 													Edit
 												</button>
 												<button
 													type="button"
 													onClick={() => setConfirmingId(client.id)}
-													className={`${smallButtonClass} text-red-700 dark:text-red-400`}
+													disabled={readOnly && client.hand_edited}
+													title={
+														readOnly && client.hand_edited
+															? DECLARED_CLIENT_NOTE
+															: undefined
+													}
+													className={`${smallButtonClass} text-red-700 disabled:opacity-50 dark:text-red-400`}
 												>
 													Delete
 												</button>

web/src/features/clients/PrefixesEditor.tsx

@@ -6,6 +6,7 @@ import { defaultGroupId } from "@/lib/defaultGroup";
 import { firstProblem, initPrefixEditor, isDirty, prefixEditorReducer, toInputs } from "./prefixEditor";
 import InlineError from "@/lib/InlineError";
 import { buttonClass, focusRing, primaryButtonClass, smallInputClass } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 interface Props {
 	prefixes: ClientPrefix[];
@@ -19,6 +20,7 @@ export default function PrefixesEditor({ prefixes, groups }: Props) {
 	const [validation, setValidation] = useState<string | null>(null);
 	const dirty = isDirty(state);
 	const fallbackGroupId = defaultGroupId(groups);
+	const readOnly = useReadOnlyConfig();
 
 	const save = () => {
 		const problem = firstProblem(state.rows);
@@ -105,7 +107,8 @@ export default function PrefixesEditor({ prefixes, groups }: Props) {
 				<button
 					type="button"
 					onClick={save}
-					disabled={!dirty || mutation.isPending}
+					disabled={!dirty || mutation.isPending || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
 					className={primaryButtonClass}
 				>
 					Save prefixes

web/src/features/groups/GroupSourcesEditor.tsx

@@ -5,6 +5,7 @@ import type { Blocklist } from "@/lib/types";
 import { sameSet, toggleSource } from "./sourceSet";
 import InlineError from "@/lib/InlineError";
 import { buttonClass, focusRing, primaryButtonClass } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 interface Props {
 	groupId: number;
@@ -16,6 +17,7 @@ export default function GroupSourcesEditor({ groupId, blocklists }: Props) {
 	const sources = useQuery(groupSourcesQuery(groupId));
 	const mutation = useMutation(groupSourcesPutMutation(queryClient));
 	const [selected, setSelected] = useState<number[] | null>(null);
+	const readOnly = useReadOnlyConfig();
 
 	if (sources.isPending) {
 		return (
@@ -58,7 +60,8 @@ export default function GroupSourcesEditor({ groupId, blocklists }: Props) {
 			<div className="mt-3 flex gap-2">
 				<button
 					type="button"
-					disabled={!dirty || mutation.isPending}
+					disabled={!dirty || mutation.isPending || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
 					onClick={() =>
 						mutation.mutate({ id: groupId, sourceIds: current }, { onSuccess: () => setSelected(null) })
 					}

web/src/features/groups/GroupsPage.tsx

@@ -12,6 +12,7 @@ import GroupSourcesEditor from "./GroupSourcesEditor";
 import InlineError from "@/lib/InlineError";
 import { focusRing, primaryButtonClass, smallButtonClass, smallInputClass } from "@/ui/classes";
 import { DEFAULT_GROUP_ID } from "@/lib/defaultGroup";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 const DEFAULT_GROUP_NOTE = "The default group cannot be renamed or deleted.";
 
@@ -23,6 +24,7 @@ export default function GroupsPage() {
 	const queryClient = useQueryClient();
 	const createMutation = useMutation(groupCreateMutation(queryClient));
 	const [newName, setNewName] = useState("");
+	const readOnly = useReadOnlyConfig();
 
 	return (
 		<section>
@@ -44,9 +46,15 @@ export default function GroupsPage() {
 					type="text"
 					value={newName}
 					onChange={(event) => setNewName(event.target.value)}
+					disabled={readOnly}
 					className={smallInputClass}
 				/>
-				<button type="submit" disabled={createMutation.isPending} className={primaryButtonClass}>
+				<button
+					type="submit"
+					disabled={createMutation.isPending || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={primaryButtonClass}
+				>
 					Create
 				</button>
 			</form>
@@ -69,6 +77,8 @@ function GroupRow({ group, blocklists }: { group: Group; blocklists: Blocklist[]
 	const [confirming, setConfirming] = useState(false);
 	const [expanded, setExpanded] = useState(false);
 	const isDefault = group.id === DEFAULT_GROUP_ID;
+	const readOnly = useReadOnlyConfig();
+	const lockNote = isDefault ? DEFAULT_GROUP_NOTE : readOnly ? READ_ONLY_HINT : undefined;
 
 	return (
 		<li className="rounded border border-zinc-200 p-4 dark:border-zinc-700">
@@ -94,7 +104,12 @@ function GroupRow({ group, blocklists }: { group: Group; blocklists: Blocklist[]
 							className={smallInputClass}
 							autoFocus
 						/>
-						<button type="submit" disabled={updateMutation.isPending} className={groupButtonClass}>
+						<button
+							type="submit"
+							disabled={updateMutation.isPending || readOnly}
+							title={readOnly ? READ_ONLY_HINT : undefined}
+							className={groupButtonClass}
+						>
 							Save
 						</button>
 						<button
@@ -115,7 +130,8 @@ function GroupRow({ group, blocklists }: { group: Group; blocklists: Blocklist[]
 					<input
 						type="checkbox"
 						checked={group.safe_search}
-						disabled={updateMutation.isPending}
+						disabled={updateMutation.isPending || readOnly}
+						title={readOnly ? READ_ONLY_HINT : undefined}
 						className={focusRing}
 						onChange={(event) =>
 							updateMutation.mutate({
@@ -138,8 +154,8 @@ function GroupRow({ group, blocklists }: { group: Group; blocklists: Blocklist[]
 					{!renaming && (
 						<button
 							type="button"
-							disabled={isDefault}
-							title={isDefault ? DEFAULT_GROUP_NOTE : undefined}
+							disabled={isDefault || readOnly}
+							title={lockNote}
 							onClick={() => {
 								setName(group.name);
 								setRenaming(true);
@@ -168,8 +184,8 @@ function GroupRow({ group, blocklists }: { group: Group; blocklists: Blocklist[]
 					) : (
 						<button
 							type="button"
-							disabled={isDefault}
-							title={isDefault ? DEFAULT_GROUP_NOTE : undefined}
+							disabled={isDefault || readOnly}
+							title={lockNote}
 							onClick={() => setConfirming(true)}
 							className={`${groupButtonClass} text-red-700 dark:text-red-400`}
 						>

web/src/features/local/RecordsTab.tsx

@@ -17,18 +17,21 @@ import {
 	rowButtonClass,
 	tableWrapClass,
 } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 const RTYPES: readonly LocalRecordType[] = ["A", "AAAA", "CNAME"];
 
 function RecordForm({
 	initial,
 	busy,
+	readOnly,
 	error,
 	onSubmit,
 	onCancel,
 }: {
 	initial?: LocalRecord;
 	busy: boolean;
+	readOnly: boolean;
 	error: unknown;
 	onSubmit: (input: LocalRecordInput) => void;
 	onCancel: () => void;
@@ -109,7 +112,12 @@ function RecordForm({
 				/>
 			</div>
 			<div className="flex gap-2">
-				<button type="submit" disabled={busy} className={largePrimaryButtonClass}>
+				<button
+					type="submit"
+					disabled={busy || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={largePrimaryButtonClass}
+				>
 					{busy ? "Saving…" : "Save"}
 				</button>
 				<button type="button" onClick={onCancel} className={largeButtonClass}>
@@ -132,18 +140,31 @@ export default function RecordsTab() {
 		remove: localRecordDeleteMutation,
 		confirmDelete: (record) => `Delete record "${record.name}"?`,
 	});
+	const readOnly = useReadOnlyConfig();
 
 	return (
 		<div>
 			<div className="mt-4 flex items-center justify-between">
 				<p className="text-sm text-zinc-500">Answers served directly for LAN names. Changes apply live.</p>
-				<button type="button" onClick={() => openForm({ mode: "create" })} className={largePrimaryButtonClass}>
+				<button
+					type="button"
+					onClick={() => openForm({ mode: "create" })}
+					disabled={readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={largePrimaryButtonClass}
+				>
 					Add record
 				</button>
 			</div>
 			<InlineError error={remove.error} />
 			{form?.mode === "create" && (
-				<RecordForm busy={create.isPending} error={create.error} onSubmit={onSubmit} onCancel={closeForm} />
+				<RecordForm
+					busy={create.isPending}
+					readOnly={readOnly}
+					error={create.error}
+					onSubmit={onSubmit}
+					onCancel={closeForm}
+				/>
 			)}
 			<div className={tableWrapClass}>
 				<table className="w-full text-left text-sm">
@@ -181,6 +202,7 @@ export default function RecordsTab() {
 										<RecordForm
 											initial={record}
 											busy={update.isPending}
+											readOnly={readOnly}
 											error={update.error}
 											onSubmit={onSubmit}
 											onCancel={closeForm}
@@ -196,15 +218,18 @@ export default function RecordsTab() {
 											<button
 												type="button"
 												onClick={() => openForm({ mode: "edit", entity: record })}
-												className={rowButtonClass}
+												disabled={readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
+												className={`${rowButtonClass} disabled:opacity-50`}
 											>
 												Edit
 											</button>
 											<button
 												type="button"
 												onClick={() => onDelete(record)}
-												disabled={remove.isPending}
-												className={`${rowButtonClass} text-red-600 dark:text-red-400`}
+												disabled={remove.isPending || readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
+												className={`${rowButtonClass} text-red-600 disabled:opacity-50 dark:text-red-400`}
 											>
 												Delete
 											</button>

web/src/features/local/ZonesTab.tsx

@@ -17,16 +17,19 @@ import {
 	rowButtonClass,
 	tableWrapClass,
 } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 function ZoneForm({
 	initial,
 	busy,
+	readOnly,
 	error,
 	onSubmit,
 	onCancel,
 }: {
 	initial?: ForwardZone;
 	busy: boolean;
+	readOnly: boolean;
 	error: unknown;
 	onSubmit: (input: ForwardZoneInput) => void;
 	onCancel: () => void;
@@ -70,7 +73,12 @@ function ZoneForm({
 				/>
 			</div>
 			<div className="flex gap-2">
-				<button type="submit" disabled={busy} className={largePrimaryButtonClass}>
+				<button
+					type="submit"
+					disabled={busy || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={largePrimaryButtonClass}
+				>
 					{busy ? "Saving…" : "Save"}
 				</button>
 				<button type="button" onClick={onCancel} className={largeButtonClass}>
@@ -93,6 +101,7 @@ export default function ZonesTab() {
 		remove: forwardZoneDeleteMutation,
 		confirmDelete: (zone) => `Delete forward zone "${zone.zone}"?`,
 	});
+	const readOnly = useReadOnlyConfig();
 
 	return (
 		<div>
@@ -100,13 +109,25 @@ export default function ZonesTab() {
 				<p className="text-sm text-zinc-500">
 					Names under these zones go to their own resolver. Changes apply live.
 				</p>
-				<button type="button" onClick={() => openForm({ mode: "create" })} className={largePrimaryButtonClass}>
+				<button
+					type="button"
+					onClick={() => openForm({ mode: "create" })}
+					disabled={readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={largePrimaryButtonClass}
+				>
 					Add zone
 				</button>
 			</div>
 			<InlineError error={remove.error} />
 			{form?.mode === "create" && (
-				<ZoneForm busy={create.isPending} error={create.error} onSubmit={onSubmit} onCancel={closeForm} />
+				<ZoneForm
+					busy={create.isPending}
+					readOnly={readOnly}
+					error={create.error}
+					onSubmit={onSubmit}
+					onCancel={closeForm}
+				/>
 			)}
 			<div className={tableWrapClass}>
 				<table className="w-full text-left text-sm">
@@ -138,6 +159,7 @@ export default function ZonesTab() {
 										<ZoneForm
 											initial={zone}
 											busy={update.isPending}
+											readOnly={readOnly}
 											error={update.error}
 											onSubmit={onSubmit}
 											onCancel={closeForm}
@@ -151,15 +173,18 @@ export default function ZonesTab() {
 											<button
 												type="button"
 												onClick={() => openForm({ mode: "edit", entity: zone })}
-												className={rowButtonClass}
+												disabled={readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
+												className={`${rowButtonClass} disabled:opacity-50`}
 											>
 												Edit
 											</button>
 											<button
 												type="button"
 												onClick={() => onDelete(zone)}
-												disabled={remove.isPending}
-												className={`${rowButtonClass} text-red-600 dark:text-red-400`}
+												disabled={remove.isPending || readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
+												className={`${rowButtonClass} text-red-600 disabled:opacity-50 dark:text-red-400`}
 											>
 												Delete
 											</button>

web/src/features/rules/RulesPage.tsx

@@ -6,6 +6,7 @@ import { groupsQuery, ruleCreateMutation, ruleDeleteMutation, rulesQuery } from
 import type { Rule, RuleAction, RuleKind } from "@/lib/types";
 import { defaultGroupId } from "@/lib/defaultGroup";
 import { dangerLinkButtonClass, inputClass, primaryButtonClass, tableWrapClass, tdClass, thClass } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 export default function RulesPage() {
 	const queryClient = useQueryClient();
@@ -19,6 +20,7 @@ export default function RulesPage() {
 	const [kind, setKind] = useState<RuleKind>("exact");
 	const [action, setAction] = useState<RuleAction>("block");
 	const [groupId, setGroupId] = useState(() => defaultGroupId(groups));
+	const readOnly = useReadOnlyConfig();
 
 	function onSubmit(event: FormEvent<HTMLFormElement>) {
 		event.preventDefault();
@@ -77,7 +79,8 @@ export default function RulesPage() {
 										<button
 											type="button"
 											onClick={() => deleteRule(rule)}
-											disabled={remove.isPending}
+											disabled={remove.isPending || readOnly}
+											title={readOnly ? READ_ONLY_HINT : undefined}
 											className={dangerLinkButtonClass}
 										>
 											Delete
@@ -154,7 +157,12 @@ export default function RulesPage() {
 						</select>
 					</div>
 				</div>
-				<button type="submit" disabled={create.isPending} className={primaryButtonClass}>
+				<button
+					type="submit"
+					disabled={create.isPending || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={primaryButtonClass}
+				>
 					{create.isPending ? "Creating…" : "Create rule"}
 				</button>
 				<InlineError error={create.error} />

web/src/features/settings/ReadOnlyConfigBanner.tsx

@@ -0,0 +1,19 @@
+import { useAuthority } from "./authority";
+
+/**
+ * File authority is a standing condition, not an event, so this banner has no
+ * dismiss button: it stays up for as long as the process runs from a file.
+ */
+export default function ReadOnlyConfigBanner() {
+	const authority = useAuthority();
+	if (authority?.mode !== "managed_file") return null;
+	return (
+		<div
+			role="status"
+			className="border-b border-amber-300 bg-amber-50 px-4 py-2 text-sm text-amber-900 dark:border-amber-800 dark:bg-amber-950 dark:text-amber-100"
+		>
+			Configuration is managed by <code className="font-mono">{authority.path}</code>. Edit the file and restart
+			nxdns to change it; the server rejects edits made here.
+		</div>
+	);
+}

web/src/features/settings/SettingsPage.tsx

@@ -5,6 +5,7 @@ import { settingsPutMutation, settingsQuery } from "@/lib/queries";
 import { buildSettingsPatch } from "@/lib/settingsDiff";
 import type { Settings, SettingsPatch } from "@/lib/types";
 import { raiseRestartBanner } from "./restartBanner";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "./authority";
 import { focusRing } from "@/ui/classes";
 
 /** True when the patch touches anything besides the write-only `web.password` (ruling 11). */
@@ -242,7 +243,8 @@ export default function SettingsPage() {
 		);
 	});
 	const patch = buildSettingsPatch(baseline, edited, password === "" ? undefined : password);
-	const saveDisabled = patch === null || passwordsMismatch || hasInvalidNumber || mutation.isPending;
+	const readOnly = useReadOnlyConfig();
+	const saveDisabled = patch === null || passwordsMismatch || hasInvalidNumber || mutation.isPending || readOnly;
 
 	function setField(section: keyof Settings, key: string, value: unknown): void {
 		setEdited((prev) => ({
@@ -273,7 +275,7 @@ export default function SettingsPage() {
 				Changes are validated as a whole; every setting requires a restart to take effect.
 			</p>
 			<form onSubmit={handleSubmit} className="mt-4 max-w-3xl">
-				<fieldset disabled={mutation.isPending} className="space-y-6">
+				<fieldset disabled={mutation.isPending || readOnly} className="space-y-6">
 					{SECTIONS.map(({ section, title, fields }) => (
 						<fieldset key={section} className="rounded border border-zinc-200 p-4 dark:border-zinc-800">
 							<legend className="px-1 text-sm font-semibold">{title}</legend>
@@ -339,6 +341,7 @@ export default function SettingsPage() {
 						<button
 							type="submit"
 							disabled={saveDisabled}
+							title={readOnly ? READ_ONLY_HINT : undefined}
 							className={`rounded bg-blue-600 px-4 py-1.5 text-sm font-medium text-white ${focusRing} disabled:bg-zinc-300 disabled:text-zinc-500 dark:disabled:bg-zinc-800`}
 						>
 							{mutation.isPending ? "Saving…" : "Save"}

web/src/features/settings/authority.test.tsx

@@ -0,0 +1,254 @@
+import { render, screen, within } from "@testing-library/react";
+import { QueryClientProvider } from "@tanstack/react-query";
+import { RouterProvider, createMemoryHistory } from "@tanstack/react-router";
+import { AuthProvider } from "@/auth/store";
+import { createQueryClient } from "@/lib/queryClient";
+import { createAppRouter } from "@/routes";
+import type { Authority, Settings, SettingsEnvelope } from "@/lib/types";
+
+// One file for the whole file-mode sweep: the settings envelope is the only
+// discovery mechanism, so every page test needs the same stubbed envelope.
+
+const CONFIG_PATH = "/etc/nxdns/config.zon";
+
+const DATABASE: Authority = { mode: "database", path: null, reconciled_at: null };
+const MANAGED_FILE: Authority = { mode: "managed_file", path: CONFIG_PATH, reconciled_at: 1754899200 };
+
+function baseSettings(): Settings {
+	return {
+		upstream: { attempt_timeout_ms: 2500, read_timeout_ms: 3000, total_timeout_ms: 5000 },
+		dns: { bind_ipv4: "0.0.0.0", bind_ipv6: "::", port: 53, rate_limit: 100, rate_window_seconds: 60 },
+		blocking: { response: "zero", ttl: 300 },
+		cache: { size: 10000, negative_ttl_max: 300 },
+		web: {
+			enabled: true,
+			bind: "127.0.0.1",
+			port: 8080,
+			session_ttl_hours: 24,
+			api_rate_limit_per_min: 60,
+			api_localhost_exempt: true,
+			sse_max_connections_per_ip: 2,
+			trusted_proxies: "",
+			auth_enabled: true,
+		},
+		doh_server: { enabled: false, bind: "0.0.0.0", port: 443, cert_path: "", key_path: "" },
+		dot_server: { enabled: false, bind: "0.0.0.0", port: 853, cert_path: "", key_path: "" },
+		edns: { ecs_mode: "strip" },
+		logging: {
+			level: "info",
+			retention_days: 30,
+			query_log_buffer_max: 10000,
+			hide_domains: false,
+			hide_client_ips: false,
+			output: "stderr",
+			file_path: "",
+			max_size_mb: 50,
+			max_files: 3,
+		},
+		disk: { min_free_mb: 100, warn_free_mb: 500 },
+		blocklist_update: { enabled: true, interval_hours: 24 },
+	};
+}
+
+function envelope(authority: Authority): SettingsEnvelope {
+	return { settings: baseSettings(), restart_required: [], authority };
+}
+
+const GROUPS = {
+	groups: [
+		{ id: 1, name: "default", safe_search: false },
+		{ id: 2, name: "kids", safe_search: true },
+	],
+};
+
+const BLOCKLISTS = {
+	blocklists: [
+		{
+			id: 1,
+			url: "https://example.com/ads.txt",
+			name: "Ads",
+			enabled: true,
+			is_suggested: false,
+			last_updated: null,
+			domain_count: 100,
+			wildcard_count: 0,
+			skipped_regex_count: 0,
+			checksum: null,
+		},
+	],
+};
+
+const RULES = {
+	rules: [
+		{
+			id: 1,
+			group_id: 1,
+			group: "default",
+			pattern: "ads.example.com",
+			kind: "exact",
+			action: "block",
+			created_at: 1700000000,
+		},
+	],
+};
+
+const CLIENTS = {
+	clients: [
+		{
+			id: 1,
+			ip: "192.168.1.10",
+			name: "laptop",
+			group_id: 1,
+			group: "default",
+			hand_edited: true,
+			first_seen: 1700000000,
+			last_seen: 1700003600,
+		},
+		{
+			id: 2,
+			ip: "192.168.1.11",
+			name: "",
+			group_id: 2,
+			group: "kids",
+			hand_edited: false,
+			first_seen: 1700000000,
+			last_seen: 1700007200,
+		},
+	],
+};
+
+const PREFIXES = {
+	client_prefixes: [{ id: 1, prefix: "192.168.1.0/24", group_id: 2, group: "kids", priority: 100 }],
+};
+
+const VERSION = { version: "0.0.0-test", git_commit: "0000000", zig_version: "0.16.0", uptime_seconds: 1 };
+
+const BASE: Record<string, unknown> = {
+	"GET /api/version": VERSION,
+	"GET /api/groups": GROUPS,
+	"GET /api/blocklists": BLOCKLISTS,
+	"GET /api/rules": RULES,
+	"GET /api/clients": CLIENTS,
+	"GET /api/client-prefixes": PREFIXES,
+};
+
+function stubFetch(map: Record<string, unknown>) {
+	vi.stubGlobal(
+		"fetch",
+		vi.fn(async (input: RequestInfo | URL, init?: RequestInit) => {
+			const key = `${init?.method ?? "GET"} ${String(input)}`;
+			const payload = map[key];
+			if (payload === undefined) {
+				return new Response(JSON.stringify({ error: `not stubbed: ${key}` }), { status: 404 });
+			}
+			return new Response(JSON.stringify(payload), {
+				status: 200,
+				headers: { "content-type": "application/json" },
+			});
+		}),
+	);
+}
+
+async function renderAt(route: string, heading: string, authority: Authority) {
+	stubFetch({ ...BASE, "GET /api/settings": envelope(authority) });
+	const queryClient = createQueryClient();
+	const router = createAppRouter(createMemoryHistory({ initialEntries: [route] }), queryClient);
+	render(
+		<AuthProvider>
+			<QueryClientProvider client={queryClient}>
+				<RouterProvider router={router} />
+			</QueryClientProvider>
+		</AuthProvider>,
+	);
+	await screen.findByRole("heading", { name: heading });
+}
+
+function button(name: string): HTMLButtonElement {
+	return screen.getByRole("button", { name }) as HTMLButtonElement;
+}
+
+function clientRow(ip: string): HTMLElement {
+	const row = screen.getByText(ip).closest("tr");
+	if (row === null) throw new Error(`no client row for ${ip}`);
+	return row;
+}
+
+afterEach(() => {
+	vi.unstubAllGlobals();
+});
+
+test("the banner names the managed file in file mode", async () => {
+	await renderAt("/rules", "Rules", MANAGED_FILE);
+
+	const banner = await screen.findByText(/configuration is managed by/i);
+	expect(banner.textContent).toContain(CONFIG_PATH);
+	expect(banner.textContent).toMatch(/restart/i);
+	expect(banner.closest('[role="status"]')).toBeTruthy();
+});
+
+test("the banner is absent in database mode", async () => {
+	await renderAt("/rules", "Rules", DATABASE);
+
+	await screen.findByRole("button", { name: "Create rule" });
+	expect(screen.queryByText(/configuration is managed by/i)).toBeNull();
+});
+
+function kidsRow(): HTMLElement {
+	const row = screen.getByText("kids").closest("li");
+	if (row === null) throw new Error("no row for group kids");
+	return row;
+}
+
+test("file mode disables the Groups create and delete controls", async () => {
+	await renderAt("/groups", "Groups", MANAGED_FILE);
+	await screen.findByText(/configuration is managed by/i);
+
+	expect(button("Create").disabled).toBe(true);
+	expect((within(kidsRow()).getByRole("button", { name: "Delete" }) as HTMLButtonElement).disabled).toBe(true);
+	expect((within(kidsRow()).getByRole("checkbox", { name: "Safe search" }) as HTMLInputElement).disabled).toBe(true);
+});
+
+test("database mode leaves the Groups create and delete controls enabled", async () => {
+	await renderAt("/groups", "Groups", DATABASE);
+	await screen.findByRole("button", { name: "Create" });
+
+	expect(button("Create").disabled).toBe(false);
+	expect((within(kidsRow()).getByRole("button", { name: "Delete" }) as HTMLButtonElement).disabled).toBe(false);
+	expect((within(kidsRow()).getByRole("checkbox", { name: "Safe search" }) as HTMLInputElement).disabled).toBe(false);
+});
+
+test("file mode disables the Rules create and delete controls", async () => {
+	await renderAt("/rules", "Rules", MANAGED_FILE);
+	await screen.findByText(/configuration is managed by/i);
+
+	expect(button("Create rule").disabled).toBe(true);
+	expect(button("Delete").disabled).toBe(true);
+});
+
+test("database mode leaves the Rules create and delete controls enabled", async () => {
+	await renderAt("/rules", "Rules", DATABASE);
+	await screen.findByRole("button", { name: "Create rule" });
+
+	expect(button("Create rule").disabled).toBe(false);
+	expect(button("Delete").disabled).toBe(false);
+});
+
+test("file mode keeps delete live for an observed client and blocks it for a declared one", async () => {
+	await renderAt("/clients", "Clients", MANAGED_FILE);
+	await screen.findByText(/configuration is managed by/i);
+
+	const declared = clientRow("192.168.1.10");
+	const observed = clientRow("192.168.1.11");
+	expect((within(declared).getByRole("button", { name: "Delete" }) as HTMLButtonElement).disabled).toBe(true);
+	expect((within(observed).getByRole("button", { name: "Delete" }) as HTMLButtonElement).disabled).toBe(false);
+	expect((within(observed).getByRole("button", { name: "Edit" }) as HTMLButtonElement).disabled).toBe(true);
+});
+
+test("file mode leaves the blocklist refresh button enabled", async () => {
+	await renderAt("/blocklists", "Blocklists", MANAGED_FILE);
+	await screen.findByText(/configuration is managed by/i);
+
+	expect(button("Update now").disabled).toBe(false);
+	expect(button("Add source").disabled).toBe(true);
+	expect((screen.getByRole("checkbox", { name: "Ads enabled" }) as HTMLInputElement).disabled).toBe(true);
+});

web/src/features/settings/authority.ts

@@ -0,0 +1,25 @@
+import { useQuery } from "@tanstack/react-query";
+import { settingsQuery } from "@/lib/queries";
+import type { Authority } from "@/lib/types";
+
+/** The one-line explanation on every control file authority takes away. */
+export const READ_ONLY_HINT = "Configuration is managed by a file; edit the file and restart nxdns.";
+
+/**
+ * The running server's configuration authority, read from the settings
+ * envelope — the only route that carries it. `undefined` until that query
+ * resolves. Every page may call this: it is the shared `["settings"]` key, so
+ * the shell's own subscription serves them all from cache.
+ */
+export function useAuthority(): Authority | undefined {
+	return useQuery(settingsQuery()).data?.authority;
+}
+
+/**
+ * True only once the server has said a file owns the configuration. While the
+ * mode is unknown nothing is disabled — the 403 is the enforcement, this is
+ * the courtesy.
+ */
+export function useReadOnlyConfig(): boolean {
+	return useAuthority()?.mode === "managed_file";
+}

web/src/features/upstreams/UpstreamForm.tsx

@@ -2,18 +2,21 @@ import { useState, type FormEvent } from "react";
 import InlineError from "@/lib/InlineError";
 import type { Upstream, UpstreamInput } from "@/lib/types";
 import { buttonClass, focusRing, inputClass, primaryButtonClass } from "@/ui/classes";
+import { READ_ONLY_HINT } from "@/features/settings/authority";
 
 const DEFAULT_PRIORITY = "100";
 
 interface UpstreamFormProps {
 	initial?: Upstream;
 	busy: boolean;
+	/** File authority: the server answers 403, so the submit stays down. */
+	readOnly: boolean;
 	error: Error | null;
 	onSubmit: (input: UpstreamInput) => Promise<void>;
 	onCancel?: () => void;
 }
 
-export default function UpstreamForm({ initial, busy, error, onSubmit, onCancel }: UpstreamFormProps) {
+export default function UpstreamForm({ initial, busy, readOnly, error, onSubmit, onCancel }: UpstreamFormProps) {
 	const [url, setUrl] = useState(initial?.url ?? "");
 	const [priority, setPriority] = useState(initial === undefined ? DEFAULT_PRIORITY : String(initial.priority));
 	const [enabled, setEnabled] = useState(initial?.enabled ?? true);
@@ -97,7 +100,12 @@ export default function UpstreamForm({ initial, busy, error, onSubmit, onCancel
 				Enabled
 			</label>
 			<div className="flex items-center gap-2">
-				<button type="submit" disabled={busy} className={primaryButtonClass}>
+				<button
+					type="submit"
+					disabled={busy || readOnly}
+					title={readOnly ? READ_ONLY_HINT : undefined}
+					className={primaryButtonClass}
+				>
 					{initial === undefined ? "Add upstream" : "Save changes"}
 				</button>
 				{onCancel !== undefined && (

web/src/features/upstreams/UpstreamsPage.tsx

@@ -6,6 +6,7 @@ import type { Upstream, UpstreamInput } from "@/lib/types";
 import { raiseRestartBanner } from "../settings/restartBanner";
 import UpstreamForm from "./UpstreamForm";
 import { dangerLinkButtonClass, focusRing, linkButtonClass, tableWrapClass, tdClass, thClass } from "@/ui/classes";
+import { READ_ONLY_HINT, useReadOnlyConfig } from "@/features/settings/authority";
 
 export default function UpstreamsPage() {
 	const queryClient = useQueryClient();
@@ -16,6 +17,7 @@ export default function UpstreamsPage() {
 	const save = useMutation(upstreamUpdateMutation(queryClient));
 	const toggle = useMutation(upstreamUpdateMutation(queryClient));
 	const remove = useMutation(upstreamDeleteMutation(queryClient));
+	const readOnly = useReadOnlyConfig();
 
 	async function submitForm(input: UpstreamInput) {
 		if (editing === null) {
@@ -84,7 +86,8 @@ export default function UpstreamsPage() {
 											type="checkbox"
 											aria-label={`${u.url} enabled`}
 											checked={u.enabled}
-											disabled={toggle.isPending}
+											disabled={toggle.isPending || readOnly}
+											title={readOnly ? READ_ONLY_HINT : undefined}
 											onChange={() => toggleEnabled(u)}
 											className={focusRing}
 										/>
@@ -95,14 +98,17 @@ export default function UpstreamsPage() {
 											<button
 												type="button"
 												onClick={() => setEditing(u)}
-												className={linkButtonClass}
+												disabled={readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
+												className={`${linkButtonClass} disabled:opacity-50`}
 											>
 												Edit
 											</button>
 											<button
 												type="button"
 												onClick={() => deleteUpstream(u)}
-												disabled={remove.isPending}
+												disabled={remove.isPending || readOnly}
+												title={readOnly ? READ_ONLY_HINT : undefined}
 												className={dangerLinkButtonClass}
 											>
 												Delete
@@ -121,6 +127,7 @@ export default function UpstreamsPage() {
 				key={editing?.id ?? "add"}
 				initial={editing ?? undefined}
 				busy={editing === null ? create.isPending : save.isPending}
+				readOnly={readOnly}
 				error={formError}
 				onSubmit={submitForm}
 				onCancel={editing === null ? undefined : () => setEditing(null)}