diff --git a/.gitignore b/.gitignore
index f6f9398..b1ef941 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,6 @@ SCOPE.md
 # raw real-data import sources (user directive 2026-09-13: never commit)
 real-data-extraction/
 dist/
+
+# dev auth/keys store (auth-keys wave): repo-root auth.json — secrets never committed
+auth.json
diff --git a/app/api/keys/[id]/route.ts b/app/api/keys/[id]/route.ts
new file mode 100644
index 0000000..7eb5cc1
--- /dev/null
+++ b/app/api/keys/[id]/route.ts
@@ -0,0 +1,49 @@
+/**
+ * PUT /api/keys/:id — save one key; DELETE — remove it (auth-keys wave,
+ * 2026-09-19). `id` is the env-var/file key name (OPENROUTER_API_KEY, …).
+ *
+ * PUT body {value}: shape-gated (owner decision — bad pastes are 400s
+ * naming the expected format, never stored; validation is SHAPE-ONLY, no
+ * live pings). Saves take effect immediately (file + env reflected; no
+ * restart). A var owned by the REAL env is persisted for later but NOT
+ * reflected — the response's status row carries shadowedByEnv so the page
+ * can explain why the saved key is not the live one.
+ *
+ * DELETE: gone from the file always; the env copy goes only when it was
+ * the store's own reflection (a real env var stays — env wins). Idempotent
+ * (absent key = success). Unknown ids are 404 — the curated catalog is
+ * the writable surface; unknown file vars are preserved, not editable.
+ */
+import { isKnownAuthKey } from "@/src/core";
+import { deleteKey, saveKey } from "@/src/server";
+
+export const dynamic = "force-dynamic";
+
+type Params = { params: Promise<{ id: string }> };
+
+export async function PUT(req: Request, { params }: Params) {
+	const { id } = await params;
+	if (!isKnownAuthKey(id)) {
+		return Response.json({ error: `unknown key "${id}"` }, { status: 404 });
+	}
+	let body: unknown;
+	try {
+		body = await req.json();
+	} catch {
+		return Response.json({ error: "body must be JSON" }, { status: 400 });
+	}
+	if (!body || typeof body !== "object" || Array.isArray(body) || typeof (body as { value?: unknown }).value !== "string") {
+		return Response.json({ error: "body must be {value: string}" }, { status: 400 });
+	}
+	const result = saveKey(id, (body as { value: string }).value);
+	if (!result.ok) return Response.json({ error: result.error }, { status: 400 });
+	return Response.json({ status: result.status });
+}
+
+export async function DELETE(_req: Request, { params }: Params) {
+	const { id } = await params;
+	if (!isKnownAuthKey(id)) {
+		return Response.json({ error: `unknown key "${id}"` }, { status: 404 });
+	}
+	return Response.json({ status: deleteKey(id) });
+}
diff --git a/app/api/keys/route.ts b/app/api/keys/route.ts
new file mode 100644
index 0000000..454526b
--- /dev/null
+++ b/app/api/keys/route.ts
@@ -0,0 +1,17 @@
+/**
+ * GET /api/keys — the auth page's key list (auth-keys wave, 2026-09-19).
+ *
+ * Every curated key (present or not) plus unknown file vars surfaced as
+ * generic rows. Masked only — last 4 + length; PLAINTEXT NEVER LEAVES THE
+ * STORE THROUGH THIS API (owner decision). `source` tells the page whether
+ * the live value comes from the environment (dev .env.local / launch env)
+ * or the file, and `shadowedByEnv` explains why a saved key is not the
+ * live one (env always wins).
+ */
+import { keyStatuses } from "@/src/server";
+
+export const dynamic = "force-dynamic";
+
+export async function GET() {
+	return Response.json({ keys: keyStatuses() });
+}
diff --git a/app/api/stt/token/route.ts b/app/api/stt/token/route.ts
index 8e021a7..f797c79 100644
--- a/app/api/stt/token/route.ts
+++ b/app/api/stt/token/route.ts
@@ -13,8 +13,10 @@
  * /auth/grant (their docs, token-based auth FAQ) — plain read/transcribe
  * keys return FORBIDDEN here.
  */
+import { keyValue } from "@/src/server";
+
 export async function GET() {
-	const key = process.env.DEEPGRAM_API_KEY;
+	const key = keyValue("DEEPGRAM_API_KEY");
 	if (!key) {
 		return Response.json(
 			{ message: "No DEEPGRAM_API_KEY — add it to auth.json (desktop) or .env.local (dev)." },
diff --git a/config.ts b/config.ts
index c027120..ffc3afa 100644
--- a/config.ts
+++ b/config.ts
@@ -182,3 +182,21 @@ export const SETTINGS_FILE = path.join(DATA_ROOT, "settings.json");
  * a vanished segment stops composing but stays on disk.
  */
 export const PROMPTS_OVERRIDE_DIR = path.join(DATA_ROOT, "prompts");
+
+/**
+ * THE AUTH/KEY STORE (auth-keys wave, 2026-09-19): BYOK provider keys in a
+ * flat {VAR: value} JSON map — the SAME file the Electron app has always
+ * hand-edited (owner decision: option A, zero migration). Desktop main.cjs
+ * passes LH_AUTH_FILE pointing at userData/auth.json (mode 0600); in dev
+ * (no Electron) the default is the repo-root auth.json (gitignored, same
+ * pattern as .env.local — a worktree may symlink it to the master copy).
+ * The SERVER reads/writes this file directly at call time (no restart to
+ * change a key); it reflects the values into process.env at boot with
+ * FILL-GAP precedence — real environment variables (incl. .env.local in
+ * dev) always win (src/server/keys.ts). Hand-edits still work: the file is
+ * re-read from disk on every API access. Secrets NEVER go in settings.json
+ * — this file keeps that role, alongside .env.local.
+ */
+export const AUTH_FILE = process.env.LH_AUTH_FILE
+	? path.resolve(process.env.LH_AUTH_FILE)
+	: path.join(ROOT, "auth.json");
diff --git a/electron/main.cjs b/electron/main.cjs
index a18cbc8..08f261f 100644
--- a/electron/main.cjs
+++ b/electron/main.cjs
@@ -4,7 +4,7 @@
  * What this process is and is not:
  *   IS:  a thin launcher + security guard around the app's real server —
  *        `next build`'s standalone server.js (Next 16), spawned as a child
- *        on 127.0.0.1 with the BYOK keys and the LH_DATA_DIR seam.
+ *        on 127.0.0.1 with the BYOK auth file and the LH_DATA_DIR seam.
  *   NOT: a host for any app logic. Everything — teacher turns, extraction,
  *        the graph — runs in the Next server, unchanged.
  *
@@ -17,8 +17,11 @@
  *   - all mutable state under userData (never inside the .app bundle —
  *     translocated apps are read-only);
  *   - keys ride the child's ENV, never argv; auth.json (BYOK) is a flat
- *     {VAR: value} JSON map, plaintext, mode 0600, hand-edited until the
- *     settings milestone builds the UI.
+ *     {VAR: value} JSON map, plaintext, mode 0600 — server-managed since
+ *     the auth-keys wave (2026-09-19): the child reads/writes it DIRECTLY
+ *     (LH_AUTH_FILE below) and reflects values into its own env. The old
+ *     spawn-time env injection retired with that wave — a copy made here
+ *     would shadow every settings-page key change until restart.
  */
 
 const { app, BrowserWindow, Menu, ipcMain, session, shell } = require("electron");
@@ -83,22 +86,12 @@ function freePort() {
 	});
 }
 
-/** BYOK keys: auth.json in userData, flat {VAR: value} map, 0600.
- *  Absent file = no keys injected — the app runs, model calls fail with the
- *  engine's own clear error until the settings milestone adds the UI.
- *  Real environment variables win over the file (process.env precedence is
- *  also Next's own env loading order, so this stays consistent). */
-function authEnv() {
-	try {
-		const raw = JSON.parse(fs.readFileSync(AUTH_FILE(), "utf-8"));
-		if (!raw || typeof raw !== "object" || Array.isArray(raw)) return {};
-		return Object.fromEntries(
-			Object.entries(raw).filter(([, v]) => typeof v === "string").map(([k, v]) => [k, v]),
-		);
-	} catch {
-		return {}; // absent or corrupt — the documented state is "no keys yet"
-	}
-}
+/** BYOK keys: auth.json in userData, flat {VAR: value} map, 0600 —
+ *  SERVER-MANAGED since the auth-keys wave (2026-09-19). This shell no
+ *  longer reads or injects it: the child gets LH_AUTH_FILE below and does
+ *  its own read/reflect/write, so a key saved in the settings page takes
+ *  effect on the next model call — no restart. Real environment variables
+ *  still win over the file inside the child (its documented rule). */
 
 function log(line) {
 	const stamp = new Date().toISOString();
@@ -123,12 +116,15 @@ function startServer(port) {
 				cwd: path.dirname(serverEntry()),
 				env: {
 					...process.env,
-					...authEnv(),
 					ELECTRON_RUN_AS_NODE: "1",
 					NODE_ENV: "production",
 					PORT: String(port),
 					HOSTNAME: "127.0.0.1", // the server defaults to 0.0.0.0 — never
 					LH_DATA_DIR: DATA_DIR(),
+					// The auth/keys store — the child reads AND writes this file itself
+					// (no env injection anymore: a spawn-time copy would shadow every
+					// settings-page key change until restart; env wins over file).
+					LH_AUTH_FILE: AUTH_FILE(),
 				},
 				stdio: ["ignore", "pipe", "pipe"],
 			},
diff --git a/src/core/auth-keys.ts b/src/core/auth-keys.ts
new file mode 100644
index 0000000..afe3fd9
--- /dev/null
+++ b/src/core/auth-keys.ts
@@ -0,0 +1,131 @@
+/**
+ * The curated auth-key catalog + shape rules (auth-keys wave, 2026-09-19).
+ * PURE, browser-safe — no fs, no env. The catalog drives the auth page's
+ * key list (label, description, where-to-get docs link) and the write-side
+ * shape validation (owner decision: SHAPE-ONLY validation, no live pings —
+ * a revoked key looks fine until a real call fails; that trade was chosen
+ * over phoning providers).
+ *
+ * The store itself is the long-standing flat {VAR: value} auth.json map
+ * (see config.AUTH_FILE): keys are identified BY their environment-variable
+ * name — the same name consumers read today (OPENROUTER_API_KEY, …), so the
+ * catalog id IS the file key and the env var, one name everywhere.
+ *
+ * Unknown vars found in the file (outside the catalog) are PRESERVED
+ * verbatim and surfaced as generic entries — forward-compat for future
+ * entries (e.g. a plans-login token) without a schema change — but they
+ * are not hand-writable through the curated API (only the catalog's keys
+ * have shapes worth checking and docs worth showing).
+ */
+
+/** One curated key entry. `id` is the env-var/file key name. */
+export interface AuthKeyInfo {
+	id: string;
+	/** Human label for the settings page. */
+	label: string;
+	/** One-sentence what-is-this-for. */
+	description: string;
+	/** Where the user gets a key (opens in the real browser via the shell). */
+	docsUrl: string;
+}
+
+export const AUTH_KEYS: readonly AuthKeyInfo[] = [
+	{
+		id: "OPENROUTER_API_KEY",
+		label: "OpenRouter",
+		description: "The main model key — every teacher, prober and sub-agent call goes through it.",
+		docsUrl: "https://openrouter.ai/settings/keys",
+	},
+	{
+		id: "DEEPGRAM_API_KEY",
+		label: "Deepgram",
+		description: "Speech-to-text key for dictation — needs ≥ Member permission in the Deepgram console to mint tokens.",
+		docsUrl: "https://console.deepgram.com/",
+	},
+	{
+		id: "GOOGLE_SEARCH_API_KEY",
+		label: "Google Search API key",
+		description: "Web-search half of the Google pair (with the CSE ID) — powers the researcher sub-agent.",
+		docsUrl: "https://developers.google.com/custom-search/v1/introduction",
+	},
+	{
+		id: "GOOGLE_CSE_ID",
+		label: "Google CSE ID",
+		description: "Programmable Search Engine ID — which engine the search API queries.",
+		docsUrl: "https://programmablesearchengine.google.com/controlpanel",
+	},
+] as const;
+
+const AUTH_KEY_IDS: ReadonlySet<string> = new Set(AUTH_KEYS.map((k) => k.id));
+
+export function isKnownAuthKey(id: string): boolean {
+	return AUTH_KEY_IDS.has(id);
+}
+
+/** Shape-check result: ok, or a 400-ready message naming the expectation. */
+export type KeyShapeResult = { ok: true } | { ok: false; error: string };
+
+/**
+ * The write-side shape gate (owner decision: reject bad pastes with 400 —
+ * a truncated or wrong-family key can never land in the store). Values are
+ * TRIMMED first (paste hygiene); empty-after-trim always fails.
+ *
+ * Families: OpenRouter keys are `sk-or-…`; Google API keys are `AIza…`;
+ * Programmable Search Engine IDs are either the legacy `digits:digits`
+ * form or a plain alphanumeric token; Deepgram publishes no key format, so
+ * the check is a truncation guard (non-empty, ≥ 20 chars, no whitespace).
+ */
+export function validateKeyShape(id: string, rawValue: string): KeyShapeResult {
+	const value = rawValue.trim();
+	const nonEmpty = (min: number) =>
+		value.length >= min && !/\s/.test(value)
+			? { ok: true as const }
+			: { ok: false as const, error: `${id} must be at least ${min} characters with no whitespace` };
+	switch (id) {
+		case "OPENROUTER_API_KEY":
+			return value.startsWith("sk-or-")
+				? nonEmpty(12)
+				: { ok: false, error: `${id} must start with "sk-or-" (OpenRouter's key format)` };
+		case "GOOGLE_SEARCH_API_KEY":
+			return value.startsWith("AIza")
+				? nonEmpty(10)
+				: { ok: false, error: `${id} must start with "AIza" (Google's API-key format)` };
+		case "GOOGLE_CSE_ID":
+			return (
+				/^[0-9]{6,}:[0-9A-Za-z_-]+$/.test(value) || /^[0-9A-Za-z]{12,}$/.test(value)
+			)
+				? { ok: true }
+				: { ok: false, error: `${id} must be the Programmable Search Engine ID (digits:digits, or the plain alphanumeric form)` };
+		case "DEEPGRAM_API_KEY":
+			// No public format — the length floor only catches truncated pastes.
+			return nonEmpty(20);
+		default:
+			return { ok: false, error: `unknown key "${id}" (supported: ${[...AUTH_KEY_IDS].join(", ")})` };
+	}
+}
+
+/** A masked key never leaves the server as plaintext (owner decision:
+ *  last 4 chars + length — enough to identify which key is stored after
+ *  rotating between several, and to spot a mis-pasted family). */
+export function maskKey(value: string): string {
+	const v = value.trim();
+	if (v.length <= 4) return `…${v}`; // degenerate paste — still never the whole value
+	return `…${v.slice(-4)}`;
+}
+
+/** One key's status row for the GET view (never carries plaintext). */
+export interface AuthKeyStatus {
+	id: string;
+	/** Catalog metadata when the key is curated; null for unknown-file-var
+	 *  entries (preserved + surfaced, but no curated form to edit through). */
+	info: AuthKeyInfo | null;
+	/** A key is present when EITHER the environment or the file has it. */
+	present: boolean;
+	/** The masked tail + character count, e.g. "…ab12 (64 chars)". */
+	masked: string | null;
+	/** Where the live value comes from, given env-wins precedence. */
+	source: "env" | "file" | "none";
+	/** True when the file holds a value that the environment shadows — the
+	 *  settings page explains why a saved key is not the live one. */
+	shadowedByEnv: boolean;
+}
diff --git a/src/core/index.ts b/src/core/index.ts
index 6796a9e..23f32d2 100644
--- a/src/core/index.ts
+++ b/src/core/index.ts
@@ -40,6 +40,10 @@ export * from "./fuzzy.ts";
 // view. Browser-safe — the Wave-4 panel imports these directly.
 export * from "./settings.ts";
 export * from "./settings-resolution.ts";
+// auth-keys.ts (auth-keys wave, 2026-09-19): the curated key catalog +
+// shape rules + masking — pure, browser-safe (the auth page binds to the
+// /api/keys routes built on it).
+export * from "./auth-keys.ts";
 // keyboard.ts: the shortcut registry + binding normalization (pure, browser-safe).
 export * from "./keyboard.ts";
 export * from "./coverage.ts";
diff --git a/src/core/ports.ts b/src/core/ports.ts
index 079d643..4efb322 100644
--- a/src/core/ports.ts
+++ b/src/core/ports.ts
@@ -190,3 +190,23 @@ export interface PromptOverrideStore {
 	 *  on-switch with no file composes the source default, inert). */
 	deleteOverride(segmentPath: string): void;
 }
+
+// ─── AuthStore — BYOK provider keys (auth-keys wave, 2026-09-19) ────────────
+
+/**
+ * The long-standing flat {VAR: value} auth.json map (config.AUTH_FILE) —
+ * the same file the Electron app has always hand-edited, now first-class
+ * server-managed. Values are opaque strings: shape validation is a
+ * server-band concern (core/auth-keys.ts validateKeyShape — the store
+ * persists what it is given); env precedence is a server-band concern
+ * too (src/server/keys.ts). Unknown vars ride along verbatim.
+ */
+export interface AuthStore {
+	/** The whole map — absent or corrupt file = {} ("no keys yet", the
+	 *  documented first-boot state). Never throws. */
+	authVars(): Record<string, string>;
+	/** Set one VAR (atomic write, mode 0600 always, other vars preserved). */
+	setAuthVar(name: string, value: string): void;
+	/** Remove one VAR if present (absent = no-op, still a silent success). */
+	deleteAuthVar(name: string): void;
+}
diff --git a/src/server/index.ts b/src/server/index.ts
index 0ffac57..58a36ef 100644
--- a/src/server/index.ts
+++ b/src/server/index.ts
@@ -26,6 +26,13 @@ export { isValidSegmentPath } from "../core/prompt-segments.ts";
 // (composition is an agent concern); the barrel re-exports it for the
 // routes — server→agent is the lawful direction (chat-handler precedent).
 export { effectivePromptSegments, allSegmentPaths, readPromptOverride } from "../agent/prompt-segments.ts";
+
+// The auth/keys composition (auth-keys wave, 2026-09-19): the curated
+// key catalog + the env-reflecting store behind GET/PUT/DELETE /api/keys.
+// Importing this module runs the idempotent boot fill-gap — every consumer
+// keeps its plain process.env reads (that seam is the point).
+export * from "./keys.ts";
+export { authStore } from "../store/auth.ts";
 export * from "./settings-body.ts";
 export * from "./turn-liveness.ts";
 export * from "./observability.ts";
diff --git a/src/server/keys.ts b/src/server/keys.ts
new file mode 100644
index 0000000..87b9126
--- /dev/null
+++ b/src/server/keys.ts
@@ -0,0 +1,170 @@
+/**
+ * The auth/keys composition (auth-keys wave, 2026-09-19): the server-side
+ * key manager behind GET/PUT/DELETE /api/keys.
+ *
+ * THE ENV SEAM (the architecture keystone): every consumer — models.ts's
+ * openRouterApiKey(), the sub-agents, web.ts, the STT route — reads
+ * process.env directly, and the agent layer may not import the store
+ * layer. Instead of rewiring five consumers across lanes, the store
+ * REFLECTS itself into the child's env: at boot (idempotent, anchored on
+ * globalThis like the extraction registry) every file var UNSET in the
+ * real env is fill-gapped into process.env, and each save/delete updates
+ * file + env together. Keys therefore take effect immediately — no restart
+ * — which is also why main.cjs's old spawn-time injection HAD to retire:
+ * an env copy made at spawn would shadow every settings-page change until
+ * restart (env wins over file).
+ *
+ * PRECEDENCE (owner decision): real environment variables (incl.
+ * .env.local in dev) always win over the file. Boot-time real-env vars
+ * are snapshotted once per process and never mutated; a PUT to one of
+ * them persists to the file (for when the env goes away) and the status
+ * honestly reports shadowedByEnv — the page explains why the saved key
+ * is not the live one.
+ *
+ * Unknown vars in the file are preserved verbatim and surfaced as
+ * generic status rows (no catalog form to edit through — only curated
+ * keys have shapes and docs; core/auth-keys.ts).
+ */
+
+import {
+	AUTH_KEYS,
+	type AuthKeyInfo,
+	type AuthKeyStatus,
+	isKnownAuthKey,
+	maskKey,
+	validateKeyShape,
+} from "../core/auth-keys.ts";
+import { authStore } from "../store/auth.ts";
+
+// The once-per-process boot record — globalThis anchor (HMR re-imports the
+// module; the snapshot must not re-run and misread fill-gapped vars as real
+// env). Same pattern as globalThis.__lhExtractionRuns.
+interface AuthBoot {
+	/** Vars that were in the REAL env at first init — env precedence's
+	 *  untouchable set. Fill-gapped vars are everything else we set. */
+	realEnv: Set<string>;
+	/** Vars WE put into process.env (the file's reflection) — deletable. */
+	fillGap: Set<string>;
+}
+const BOOT_KEY = Symbol.for("lh.authBoot");
+
+function boot(): AuthBoot {
+	const g = globalThis as Record<symbol, AuthBoot | undefined>;
+	if (!g[BOOT_KEY]) g[BOOT_KEY] = { realEnv: new Set(), fillGap: new Set() };
+	return g[BOOT_KEY];
+}
+
+/**
+ * The boot fill-gap — idempotent. First call snapshots which managed names
+ * are real env; later calls (HMR re-import, or after a hand-edit) only fill
+ * vars still unset in the env, so a var deleted through the API never
+ * resurrects (its file entry is gone too).
+ */
+export function initAuthEnv(): void {
+	const record = boot();
+	const fileVars = authStore.authVars();
+	const managed = new Set<string>([...Object.keys(fileVars), ...AUTH_KEYS.map((k) => k.id)]);
+	if (record.realEnv.size === 0 && record.fillGap.size === 0) {
+		// First init in this process: what's already in the env is REAL env.
+		for (const name of managed) {
+			if (process.env[name] !== undefined) record.realEnv.add(name);
+		}
+	}
+	for (const [name, value] of Object.entries(fileVars)) {
+		if (!isManagedName(name)) continue;
+		if (process.env[name] === undefined) {
+			process.env[name] = value;
+			record.fillGap.add(name);
+		}
+	}
+}
+
+/** The managed name-space: catalog keys + whatever the file holds (unknown
+ *  vars are managed too — preserved, surfaced, env-reflected — just not
+ *  editable through the curated API). */
+function isManagedName(name: string): boolean {
+	return isKnownAuthKey(name) || name in authStore.authVars();
+}
+
+/**
+ * The pure status projection — exported for tests. `env` is the live
+ * process env view; `realEnv` the boot snapshot (env precedence).
+ */
+export function resolveKeyStatuses(
+	fileVars: Record<string, string>,
+	env: Record<string, string | undefined>,
+	realEnv: ReadonlySet<string>,
+): AuthKeyStatus[] {
+	const ids = new Set<string>([...AUTH_KEYS.map((k) => k.id), ...Object.keys(fileVars)]);
+	const rows: AuthKeyStatus[] = [];
+	for (const id of ids) {
+		const envValue = env[id];
+		const fileValue = fileVars[id];
+		const isRealEnv = realEnv.has(id);
+		// Env wins: the live value is the env's when set (real or reflected —
+		// post fill-gap the file's values LIVE in env, so realEnv is what
+		// distinguishes a REAL env var from the store's own reflection).
+		const live = envValue !== undefined ? envValue : fileValue;
+		rows.push({
+			id,
+			info: AUTH_KEYS.find((k) => k.id === id) ?? null,
+			present: live !== undefined,
+			masked: live !== undefined ? `${maskKey(live)} (${live.trim().length} chars)` : null,
+			source: isRealEnv ? "env" : live !== undefined ? "file" : "none",
+			shadowedByEnv: isRealEnv && fileValue !== undefined && envValue !== fileValue,
+		});
+	}
+	return rows;
+}
+
+/** The GET view: every curated key (present or not) + unknown file vars. */
+export function keyStatuses(): AuthKeyStatus[] {
+	return resolveKeyStatuses(authStore.authVars(), process.env, boot().realEnv);
+}
+
+/** The live value for one var, env-first (the env-wins rule) — the canonical
+ *  read for consumers that don't live behind the @/src/server barrel (the
+ *  STT route was the one cold-boot hole: a first-ever request to it would
+ *  otherwise read env before any fill-gap ran). */
+export function keyValue(id: string): string | undefined {
+	return process.env[id] ?? authStore.authVars()[id];
+}
+
+/**
+ * Save one key (PUT). Shape gate first (owner decision: bad pastes are
+ * 400s, never stored), then the file write, then the env reflection. A
+ * var that the REAL env owns is not reflected (env wins — the status row
+ * 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 = validateKeyShape(id, value);
+	if (!shape.ok) return { ok: false, error: shape.error };
+	const trimmed = value.trim();
+	authStore.setAuthVar(id, trimmed);
+	const record = boot();
+	if (!record.realEnv.has(id)) {
+		process.env[id] = trimmed;
+		record.fillGap.add(id);
+	}
+	// validateKeyShape guarantees catalog membership, so the row exists.
+	return { ok: true, status: keyStatuses().find((s) => s.id === id)! };
+}
+
+/**
+ * Remove one key (DELETE): gone from the file always; gone from the env
+ * only when the env copy was OURS (fill-gap) — a real env var stays (env
+ * wins) and the status shows the key still present from env.
+ */
+export function deleteKey(id: string): AuthKeyStatus {
+	authStore.deleteAuthVar(id);
+	const record = boot();
+	if (record.fillGap.has(id) && !record.realEnv.has(id)) {
+		delete process.env[id];
+		record.fillGap.delete(id);
+	}
+	return keyStatuses().find((s) => s.id === id)!;
+}
+
+// Reflect the file into the env at first import (idempotent; the module is
+// imported by every route/handler path that touches keys).
+initAuthEnv();
diff --git a/src/store/auth.ts b/src/store/auth.ts
new file mode 100644
index 0000000..2fe6edd
--- /dev/null
+++ b/src/store/auth.ts
@@ -0,0 +1,63 @@
+/**
+ * The AuthStore adapter (auth-keys wave, 2026-09-19): the flat {VAR: value}
+ * auth.json map at config.AUTH_FILE — the SAME file the Electron app has
+ * always hand-edited (owner decision: option A — same file, env-located,
+ * zero migration). 0600, atomic writes, hand-edits keep working (the file
+ * is re-read from disk on every access).
+ *
+ * The server (src/server/keys.ts) is the only intended writer: it applies
+ * shape validation before setAuthVar and env precedence on top of
+ * authVars(). This adapter persists what it is given, never throws
+ * (absent/corrupt file = {} = "no keys yet", the documented first-boot
+ * state, matching settings doctrine), and preserves unknown vars verbatim
+ * (forward-compat: future entries — e.g. a plans-login token — ride along
+ * untouched until a catalog entry adopts them).
+ */
+
+import fs from "node:fs";
+import path from "node:path";
+import { AUTH_FILE } from "../../config.ts";
+import type { AuthStore } from "../core/ports.ts";
+
+/** The flat string→string map, or {} for absent/corrupt/non-object. */
+function readMap(): Record<string, string> {
+	try {
+		const raw = JSON.parse(fs.readFileSync(AUTH_FILE, "utf-8"));
+		if (!raw || typeof raw !== "object" || Array.isArray(raw)) return {};
+		return Object.fromEntries(
+			Object.entries(raw).filter(([, v]) => typeof v === "string") as [string, string][],
+		);
+	} catch {
+		return {}; // absent or corrupt — the documented state is "no keys yet"
+	}
+}
+
+/** Write the map atomically at mode 0600: a partial write must never
+ *  leave a 0644 file (secrets) or a truncated JSON (looks like "no keys").
+ *  tmp-in-same-dir + rename keeps the swap atomic; chmod BEFORE the
+ *  rename so the mode never exists relaxed on the final path. */
+function writeMap(map: Record<string, string>): void {
+	const dir = path.dirname(AUTH_FILE);
+	fs.mkdirSync(dir, { recursive: true });
+	const tmp = path.join(dir, `.auth.json.tmp-${process.pid}`);
+	fs.writeFileSync(tmp, `${JSON.stringify(map, null, "\t")}\n`, { mode: 0o600 });
+	fs.chmodSync(tmp, 0o600); // umask may have relaxed the create mode
+	fs.renameSync(tmp, AUTH_FILE);
+}
+
+export const authStore: AuthStore = {
+	authVars() {
+		return readMap();
+	},
+	setAuthVar(name, value) {
+		const map = readMap();
+		map[name] = value;
+		writeMap(map);
+	},
+	deleteAuthVar(name) {
+		const map = readMap();
+		if (!(name in map)) return; // absent = silent success, idempotent
+		delete map[name];
+		writeMap(map);
+	},
+};
diff --git a/tests/auth-keys.test.ts b/tests/auth-keys.test.ts
new file mode 100644
index 0000000..0f4cf84
--- /dev/null
+++ b/tests/auth-keys.test.ts
@@ -0,0 +1,88 @@
+/**
+ * The curated auth-key catalog + shape rules (auth-keys wave, 2026-09-19)
+ * — PURE module, so this file owns no fs. Owner decisions being pinned:
+ *  - the catalog is exactly the four known keys, ids = env-var names;
+ *  - validation is SHAPE-ONLY (no live pings) and bad pastes are 400s;
+ *  - masking is last-4 + length — plaintext never leaves the store.
+ */
+
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+import { AUTH_KEYS, isKnownAuthKey, maskKey, validateKeyShape } from "../src/core/auth-keys.ts";
+
+describe("the catalog", () => {
+	it("is exactly the four curated keys, ids = env-var names", () => {
+		assert.deepEqual(
+			AUTH_KEYS.map((k) => k.id),
+			["OPENROUTER_API_KEY", "DEEPGRAM_API_KEY", "GOOGLE_SEARCH_API_KEY", "GOOGLE_CSE_ID"],
+		);
+		for (const k of AUTH_KEYS) {
+			assert.ok(k.label.length > 0, `${k.id} has a label`);
+			assert.ok(k.description.length > 0, `${k.id} has a description`);
+			assert.ok(k.docsUrl.startsWith("https://"), `${k.id} has a docs link`);
+		}
+	});
+
+	it("isKnownAuthKey: catalog yes, everything else no", () => {
+		assert.ok(isKnownAuthKey("OPENROUTER_API_KEY"));
+		assert.ok(isKnownAuthKey("GOOGLE_CSE_ID"));
+		assert.ok(!isKnownAuthKey("OPENROUTER"));
+		assert.ok(!isKnownAuthKey("FUTURE_PLANS_TOKEN"));
+		assert.ok(!isKnownAuthKey(""));
+	});
+});
+
+describe("validateKeyShape (the 400 gate)", () => {
+	it("OpenRouter: sk-or- prefix required, length floor past it", () => {
+		assert.deepEqual(validateKeyShape("OPENROUTER_API_KEY", "sk-or-v1-abc123def456ghi789jkl012"), { ok: true });
+		assert.ok(!validateKeyShape("OPENROUTER_API_KEY", "sk-proj-abcdefghij").ok, "wrong family (OpenAI paste)");
+		assert.ok(!validateKeyShape("OPENROUTER_API_KEY", "sk-or-").ok, "prefix alone is a truncation");
+		assert.ok(!validateKeyShape("OPENROUTER_API_KEY", "  ").ok, "empty fails");
+	});
+
+	it("Google API key: AIza prefix required", () => {
+		assert.ok(validateKeyShape("GOOGLE_SEARCH_API_KEY", "AIzaSyD-abcdef1234").ok);
+		assert.ok(!validateKeyShape("GOOGLE_SEARCH_API_KEY", "sk-or-v1-abcdefghij").ok, "wrong family");
+		assert.ok(!validateKeyShape("GOOGLE_SEARCH_API_KEY", "AIza").ok, "prefix alone fails");
+	});
+
+	it("CSE ID: legacy digits:digits OR plain token form", () => {
+		assert.ok(validateKeyShape("GOOGLE_CSE_ID", "017576662512468239146:omuauf_lfve").ok);
+		assert.ok(validateKeyShape("GOOGLE_CSE_ID", "a1b2c3d4e5f6g7h8j9k0lmnop").ok);
+		assert.ok(!validateKeyShape("GOOGLE_CSE_ID", "17:short").ok, "short legacy form fails");
+		assert.ok(!validateKeyShape("GOOGLE_CSE_ID", "has whitespace here").ok);
+		assert.ok(!validateKeyShape("GOOGLE_CSE_ID", "sk-or-v1-abcdefg").ok, "wrong family");
+	});
+
+	it("Deepgram: no public format — a ≥20-char truncation guard, no whitespace", () => {
+		assert.ok(validateKeyShape("DEEPGRAM_API_KEY", "a".repeat(40)).ok);
+		assert.ok(!validateKeyShape("DEEPGRAM_API_KEY", "a".repeat(19)).ok, "truncated paste");
+		assert.ok(!validateKeyShape("DEEPGRAM_API_KEY", "a b c d e f g h i j k l m n o p q r s").ok, "whitespace");
+	});
+
+	it("trims surrounding paste whitespace before checking", () => {
+		assert.ok(validateKeyShape("OPENROUTER_API_KEY", "  sk-or-v1-abc123def456  \n").ok);
+	});
+
+	it("unknown ids are rejected with the supported list", () => {
+		const r = validateKeyShape("SOMETHING_ELSE", "whatever");
+		assert.ok(!r.ok);
+		if (!r.ok) assert.match(r.error, /SOMETHING_ELSE.*OPENROUTER_API_KEY/);
+	});
+});
+
+describe("maskKey (plaintext never leaves)", () => {
+	it("shows the last 4 only", () => {
+		assert.equal(maskKey("sk-or-v1-abcdefgh1234"), "…1234");
+	});
+
+	it("never reveals a degenerate short value in full", () => {
+		assert.equal(maskKey("ab"), "…ab");
+		assert.equal(maskKey("abcd"), "…abcd");
+		assert.equal(maskKey("abcde"), "…bcde");
+	});
+
+	it("trims before masking", () => {
+		assert.equal(maskKey("  sk-or-v1-xyzw9  "), "…yzw9");
+	});
+});
diff --git a/tests/auth-store.test.ts b/tests/auth-store.test.ts
new file mode 100644
index 0000000..7c4b822
--- /dev/null
+++ b/tests/auth-store.test.ts
@@ -0,0 +1,80 @@
+/**
+ * The AuthStore fs adapter (auth-keys wave, 2026-09-19) — flat {VAR: value}
+ * map at config.AUTH_FILE. THIS FILE is the sole owner of its auth file:
+ * LH_AUTH_FILE is redirected to a fresh tmp dir BEFORE the first config
+ * import (the seam is module-load-bound — data-dir-seam precedent), so no
+ * hand-edited dev/desktop auth.json is ever touched.
+ *
+ * Pinning: absent/corrupt = {} ("no keys yet"); set/delete round-trip with
+ * unknown vars preserved verbatim; the file is ALWAYS mode 0600 (secrets);
+ * writes are atomic (tmp+rename — no partial JSON state).
+ */
+
+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 TMP = fs.mkdtempSync(path.join(os.tmpdir(), "lh-auth-store-"));
+process.env.LH_AUTH_FILE = path.join(TMP, "auth.json");
+
+// Import AFTER the env redirect — module-load-bound seam.
+const { authStore } = await import("../src/store/auth.ts");
+const { AUTH_FILE } = await import("../config.ts");
+
+after(() => {
+	fs.rmSync(TMP, { recursive: true, force: true });
+});
+
+describe("AuthStore adapter", () => {
+	it("absent file = {} (the documented first-boot state), never throws", () => {
+		assert.deepEqual(authStore.authVars(), {});
+	});
+
+	it("set → read round-trip; trim is the CALLER's (server's) job, verbatim here", () => {
+		authStore.setAuthVar("OPENROUTER_API_KEY", "sk-or-v1-abc");
+		assert.equal(authStore.authVars().OPENROUTER_API_KEY, "sk-or-v1-abc");
+	});
+
+	it("the file is mode 0600 (secrets), also after rewrites", () => {
+		authStore.setAuthVar("DEEPGRAM_API_KEY", "d".repeat(40));
+		const first = fs.statSync(AUTH_FILE).mode & 0o777;
+		assert.equal(first, 0o600);
+		authStore.setAuthVar("DEEPGRAM_API_KEY", "e".repeat(40));
+		assert.equal(fs.statSync(AUTH_FILE).mode & 0o777, 0o600, "rewrite keeps 0600");
+	});
+
+	it("set preserves unknown vars verbatim (forward-compat)", () => {
+		fs.writeFileSync(AUTH_FILE, JSON.stringify({ FUTURE_PLANS_TOKEN: "opaque-xyz", KEEP: "me" }));
+		authStore.setAuthVar("OPENROUTER_API_KEY", "sk-or-v1-new");
+		const vars = authStore.authVars();
+		assert.equal(vars.FUTURE_PLANS_TOKEN, "opaque-xyz");
+		assert.equal(vars.KEEP, "me");
+		assert.equal(vars.OPENROUTER_API_KEY, "sk-or-v1-new");
+	});
+
+	it("corrupt/non-object file = {} — never throws, looks like first boot", () => {
+		fs.writeFileSync(AUTH_FILE, "{not json");
+		assert.deepEqual(authStore.authVars(), {});
+		fs.writeFileSync(AUTH_FILE, JSON.stringify(["an", "array"]));
+		assert.deepEqual(authStore.authVars(), {});
+		fs.writeFileSync(AUTH_FILE, JSON.stringify({ OK: "fine", bad: 42 }));
+		assert.deepEqual(authStore.authVars(), { OK: "fine" }, "non-string values drop");
+	});
+
+	it("delete removes just that var; absent delete = silent no-op", () => {
+		fs.writeFileSync(AUTH_FILE, JSON.stringify({ A: "1", B: "2" }));
+		authStore.deleteAuthVar("A");
+		assert.deepEqual(authStore.authVars(), { B: "2" });
+		authStore.deleteAuthVar("NOT_THERE");
+		assert.deepEqual(authStore.authVars(), { B: "2" });
+	});
+
+	it("atomic writes: no tmp leftovers, valid JSON on disk every time", () => {
+		authStore.setAuthVar("OPENROUTER_API_KEY", "sk-or-v1-final");
+		const files = fs.readdirSync(TMP).filter((f) => f.startsWith(".auth.json.tmp"));
+		assert.deepEqual(files, [], "no tmp file survives the rename");
+		JSON.parse(fs.readFileSync(AUTH_FILE, "utf-8")); // must parse
+	});
+});
diff --git a/tests/server-keys.test.ts b/tests/server-keys.test.ts
new file mode 100644
index 0000000..ad4f480
--- /dev/null
+++ b/tests/server-keys.test.ts
@@ -0,0 +1,162 @@
+/**
+ * The keys composition (auth-keys wave, 2026-09-19): env-reflecting store +
+ * env-wins precedence + the masked status view. Owner decisions pinned:
+ *  - real env always wins; a PUT to an env-owned var persists to the file
+ *    but never overwrites the env copy (status reports shadowedByEnv);
+ *  - saves/deletes take effect immediately (file + process.env together);
+ *  - unknown file vars are preserved and surfaced, never editable.
+ *
+ * LH_AUTH_FILE redirects to a fresh tmp dir BEFORE the imports (the seam is
+ * module-load bound); the \"real env\" var is set before src/server/keys.ts
+ * first loads so the boot snapshot treats it as real environment. All
+ * values here are throwaway test strings — never real secrets.
+ */
+
+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, describe, it } from "node:test";
+
+// THIS PROCESS'S ENV IS THE TEST SUBJECT — strip any inherited catalog vars
+// (a developer shell may export REAL keys; tests use throwaway values only,
+// never real secrets). The strip affects only this disposable child process.
+for (const varName of [
+	"OPENROUTER_API_KEY",
+	"DEEPGRAM_API_KEY",
+	"GOOGLE_SEARCH_API_KEY",
+	"GOOGLE_CSE_ID",
+	"FUTURE_PLANS_TOKEN",
+]) {
+	delete process.env[varName];
+}
+
+const TMP = fs.mkdtempSync(path.join(os.tmpdir(), "lh-server-keys-"));
+const AUTH = path.join(TMP, "auth.json");
+process.env.LH_AUTH_FILE = AUTH;
+
+// The file BEFORE first boot: a shadowed OpenRouter (env will differ) + an
+// unknown var that must survive every write and surface as a generic row.
+fs.writeFileSync(
+	AUTH,
+	JSON.stringify({
+		OPENROUTER_API_KEY: "sk-or-v1-filefilefile",
+		FUTURE_PLANS_TOKEN: "opaque-plans-token",
+	}),
+);
+// Real env (set BEFORE the module's first import → boot snapshots it):
+process.env.OPENROUTER_API_KEY = "sk-or-v1-envvalue99";
+
+// Import AFTER env setup — module init runs the boot fill-gap + snapshot.
+const { deleteKey, initAuthEnv, keyStatuses, keyValue, resolveKeyStatuses, saveKey } = await import(
+	"../src/server/keys.ts"
+);
+const { authStore } = await import("../src/store/auth.ts");
+
+const ENV_OWNED = "sk-or-v1-envvalue99";
+
+after(() => {
+	delete process.env.OPENROUTER_API_KEY;
+	delete process.env.DEEPGRAM_API_KEY;
+	fs.rmSync(TMP, { recursive: true, force: true });
+});
+
+describe("boot fill-gap + precedence", () => {
+	it("env-owned var: env wins, shadow reported, file copy kept", () => {
+		const row = keyStatuses().find((s) => s.id === "OPENROUTER_API_KEY")!;
+		assert.equal(row.source, "env");
+		assert.ok(row.shadowedByEnv, "file value differs from the env value");
+		assert.equal(row.masked, `…${ENV_OWNED.slice(-4)} (${ENV_OWNED.length} chars)`);
+		assert.equal(authStore.authVars().OPENROUTER_API_KEY, "sk-or-v1-filefilefile", "file copy untouched");
+	});
+
+	it("unknown file var: fill-gapped into env, surfaced as a generic row", () => {
+		assert.equal(process.env.FUTURE_PLANS_TOKEN, "opaque-plans-token", "reflected at boot");
+		const row = keyStatuses().find((s) => s.id === "FUTURE_PLANS_TOKEN")!;
+		assert.equal(row.info, null, "no curated form");
+		assert.equal(row.source, "file");
+		assert.ok(row.present);
+	});
+
+	it("absent curated keys: not present, source none", () => {
+		const row = keyStatuses().find((s) => s.id === "DEEPGRAM_API_KEY")!;
+		assert.ok(!row.present);
+		assert.equal(row.source, "none");
+		assert.equal(row.masked, null);
+		assert.ok(row.info, "catalog metadata still present for the page form");
+	});
+
+	it("keyValue resolves env-first", () => {
+		assert.equal(keyValue("OPENROUTER_API_KEY"), ENV_OWNED);
+		assert.equal(keyValue("FUTURE_PLANS_TOKEN"), "opaque-plans-token");
+		assert.equal(keyValue("DEEPGRAM_API_KEY"), undefined);
+	});
+});
+
+describe("saveKey / deleteKey (immediate effect, no restart)", () => {
+	it("save reflects into env + file (fill-gap set)", () => {
+		const value = "d".repeat(40); // throwaway, ≥ Deepgram floor
+		const r = saveKey("DEEPGRAM_API_KEY", value);
+		assert.ok(r.ok);
+		assert.equal(process.env.DEEPGRAM_API_KEY, value, "env updated immediately");
+		assert.equal(authStore.authVars().DEEPGRAM_API_KEY, value, "file updated");
+		assert.equal(r.status.source, "file", "the reflected copy is the store's — the file is its origin of truth");
+		assert.ok(!r.status.shadowedByEnv);
+	});
+
+	it("save to an env-owned var: file updated, env NOT overwritten, shadow reported", () => {
+		const r = saveKey("OPENROUTER_API_KEY", "sk-or-v1-newvalue12345");
+		assert.ok(r.ok);
+		assert.equal(process.env.OPENROUTER_API_KEY, ENV_OWNED, "real env untouched");
+		assert.equal(authStore.authVars().OPENROUTER_API_KEY, "sk-or-v1-newvalue12345", "file updated for later");
+		assert.ok(r.status.shadowedByEnv);
+	});
+
+	it("bad shape: rejected, nothing stored or reflected", () => {
+		const before = JSON.stringify(authStore.authVars());
+		const r = saveKey("DEEPGRAM_API_KEY", "short");
+		assert.ok(!r.ok);
+		if (!r.ok) assert.match(r.error, /at least 20/);
+		assert.equal(JSON.stringify(authStore.authVars()), before);
+		assert.equal(process.env.DEEPGRAM_API_KEY, "d".repeat(40));
+	});
+
+	it("unknown id: rejected with the supported list", () => {
+		const r = saveKey("FUTURE_PLANS_TOKEN", "anything-at-all-here");
+		assert.ok(!r.ok);
+		if (!r.ok) assert.match(r.error, /FUTURE_PLANS_TOKEN/);
+	});
+
+	it("delete removes env + file for fill-gap vars", () => {
+		const row = deleteKey("DEEPGRAM_API_KEY");
+		assert.ok(!row.present);
+		assert.equal(process.env.DEEPGRAM_API_KEY, undefined, "env copy was ours — removed");
+		assert.ok(!("DEEPGRAM_API_KEY" in authStore.authVars()));
+	});
+
+	it("delete of an env-owned var: file copy gone, env remains (env wins)", () => {
+		const row = deleteKey("OPENROUTER_API_KEY");
+		assert.equal(row.source, "env");
+		assert.ok(row.present, "still live from the real env");
+		assert.ok(!row.shadowedByEnv, "nothing left in the file to shadow");
+		assert.equal(process.env.OPENROUTER_API_KEY, ENV_OWNED);
+	});
+
+	it("re-running initAuthEnv is idempotent — deleted vars never resurrect", () => {
+		initAuthEnv();
+		assert.equal(process.env.DEEPGRAM_API_KEY, undefined, "file entry gone → no re-fill");
+	});
+});
+
+describe("resolveKeyStatuses (pure projection)", () => {
+	it("same value in env and file is NOT shadowed (redundant, not misleading)", () => {
+		const row = resolveKeyStatuses(
+			{ GOOGLE_SEARCH_API_KEY: "AIzaSame1234" },
+			{ GOOGLE_SEARCH_API_KEY: "AIzaSame1234" },
+			new Set(["GOOGLE_SEARCH_API_KEY"]),
+		).find((s) => s.id === "GOOGLE_SEARCH_API_KEY")!;
+		assert.ok(row, "the curated id is always in the projection");
+		assert.equal(row.source, "env");
+		assert.ok(!row.shadowedByEnv, "same value both places: redundant, not shadowed");
+	});
+});