feat(search): Tavily + Brave behind a search-provider port; Google CSE retires

Search port + model slots wave, chunk A (owner design, 2026-09-20):
- core/search.ts: SearchHit + SearchProvider port + SearchStatus —
  pure, browser-safe; adapters arrive as injected dependencies.
- server/search.ts: Tavily + Brave adapters (wire shapes VERIFIED
  against docs.tavily.com's OpenAPI + Brave's dashboard docs — Tavily
  auth is the Bearer header, not the legacy body api_key; Brave is
  X-Subscription-Token) + engine resolution per owner decisions: a key
  ALONE activates its engine (no engine choice needed), explicit
  agent.search.engine pins the preference (both keys: Tavily first),
  a pinned engine with a missing key is honestly unavailable — no
  silent fallback, no default engine.
- Curated keys catalog: GOOGLE_SEARCH_API_KEY/GOOGLE_CSE_ID retire
  (CSE closed to new customers, dies Jan 2027 — stored values become
  preserved unknown vars); TAVILY_API_KEY (tvly- shape) + BRAVE_API_KEY
  (length guard) join. UI keys-section TOOL_IDS now derives from the
  catalog — cannot drift.
- GET /api/search: {available, engine, reason} — the honest status for
  the settings gray-out; researcher-disable semantics ride the same
  signal (Teacher stream rewires the tool onto the port).
- agent.search settings field (schema + sanitizer + strict parser);
  web.ts's WebSearchResult is now the core SearchHit (re-exported).

src/agent/tools/web.ts

@@ -1,5 +1,10 @@
 import { z } from "zod";
 import { lhTool } from "../lh-tool.ts";
+// The search-hit shape lives in the core port since the search wave
+// (2026-09-20) — this module keeps the historical alias so callers don't
+// churn; the tool's rewiring onto the port is the Teacher stream's.
+import type { SearchHit as WebSearchResult } from "../../core/search.ts";
+export type { WebSearchResult };
 import { Readability } from "@mozilla/readability";
 import { parseHTML } from "linkedom";
 import TurndownService from "turndown";
@@ -22,12 +27,7 @@ import TurndownService from "turndown";
  */
 
 // ── web_search ───────────────────────────────────────────────────────────────
-
-export interface WebSearchResult {
-	title: string;
-	url: string;
-	snippet: string;
-}
+// (WebSearchResult is the core SearchHit, re-exported above.)
 
 function searchCredentials(): { apiKey: string; cseId: string } | null {
 	const apiKey = process.env.GOOGLE_SEARCH_API_KEY;

src/core/auth-keys.ts

@@ -37,16 +37,16 @@ export const AUTH_KEYS: readonly AuthKeyInfo[] = [
 		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: "TAVILY_API_KEY",
+		label: "Tavily",
+		description: "Web-search engine for the researcher sub-agent (AI-native search API). Setting the key activates it — no engine toggle needed.",
+		docsUrl: "https://app.tavily.com/",
 	},
 	{
-		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",
+		id: "BRAVE_API_KEY",
+		label: "Brave Search",
+		description: "Web-search engine for the researcher sub-agent — the alternative to Tavily. Setting the key activates it.",
+		docsUrl: "https://brave.com/search/api/",
 	},
 ] as const;
 
@@ -138,8 +138,8 @@ export type KeyShapeResult = { ok: true } | { ok: false; error: string };
  * a truncated or wrong-family key can never land in the store). Values are
  * TRIMMED first (paste hygiene); empty-after-trim always fails.
  *
- * CURATED keys carry family rules (Google AIza…, the CSE forms,
- * Deepgram's length floor — a truncation guard; it publishes no format).
+ * CURATED keys carry family rules (Tavily's tvly-… prefix; Brave and
+ * Deepgram publish no format — length floors + paste hygiene only).
  * MODEL-PROVIDER keys use genericProviderKeyGuard below instead (families
  * vary by provider — only paste hygiene applies; owner spec: min length
  * ~12, no whitespace). OPENROUTER_API_KEY moved to the generic guard with
@@ -152,16 +152,13 @@ export function validateKeyShape(id: string, rawValue: string): KeyShapeResult {
 			? { ok: true as const }
 			: { ok: false as const, error: `${id} must be at least ${min} characters with no whitespace` };
 	switch (id) {
-		case "GOOGLE_SEARCH_API_KEY":
-			return value.startsWith("AIza")
-				? nonEmpty(10)
-				: { ok: false, error: `${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: `${id} must be the Programmable Search Engine ID (digits:digits, or the plain alphanumeric form)` };
+		case "TAVILY_API_KEY":
+			return value.startsWith("tvly-")
+				? nonEmpty(20)
+				: { ok: false, error: `${id} must start with "tvly-" (Tavily's key format)` };
+		case "BRAVE_API_KEY":
+			// No public format — a length floor + paste hygiene only.
+			return nonEmpty(20);
 		case "DEEPGRAM_API_KEY":
 			// No public format — the length floor only catches truncated pastes.
 			return nonEmpty(20);

src/core/index.ts

@@ -41,6 +41,7 @@ export * from "./fuzzy.ts";
 // view. Browser-safe — the Wave-4 panel imports these directly.
 export * from "./settings.ts";
 export * from "./settings-resolution.ts";
+export * from "./search.ts"; // search port (search wave, 2026-09-20)
 // 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).

src/core/search.ts

@@ -0,0 +1,53 @@
+/**
+ * The search-provider port (search port + model slots wave, 2026-09-20).
+ *
+ * Search engines are pluggable behind ONE seam: the settings record names a
+ * preferred engine (agent.search.engine — optional), keys live in the auth
+ * store (TAVILY_API_KEY / BRAVE_API_KEY — curated catalog), and the server
+ * composes the live adapter. The Google CSE engine retired with this wave
+ * (closed to new customers; dies Jan 2027) — replaced by Tavily + Brave.
+ *
+ * Owner decisions baked here:
+ *  - NO default engine in the factory record: an engine is live iff its
+ *    key is present. With a key, the engine auto-activates (the user never
+ *    chooses an engine to make search work — setting the key is enough);
+ *    agent.search.engine is only an explicit preference.
+ *  - Nothing silently falls back: no engine live = search is honestly
+ *    unavailable (the tool says so; the researcher sub-agent is disabled
+ *    by the agent layer on the same signal — that rewiring is the Teacher
+ *    stream's, on this port).
+ *
+ * Pure types + protocol docs only (browser-safe, no node imports): the
+ * adapters are server-side (src/server/search.ts) and arrive as injected
+ * dependencies — the agent-layer tool depends on THIS port only.
+ */
+
+/** One search result row — the shape every adapter must produce (the
+ *  researcher's tool contract; same fields the old Google adapter emitted). */
+export interface SearchHit {
+	title: string;
+	url: string;
+	snippet: string;
+}
+
+/** The engine ids this wave ships (the catalog: curated keys + adapters). */
+export type SearchEngineId = "tavily" | "brave";
+
+/** A live search engine: an id (for status/labels) + one operation. The
+ *  adapters own their wire protocol (fetch, timeouts, error mapping) —
+ *  callers see only this. `search` throws on failure (adapters map HTTP
+ *  errors to clear Error messages); the tool layer catches and reports. */
+export interface SearchProvider {
+	id: SearchEngineId;
+	search(query: string, count: number): Promise<SearchHit[]>;
+}
+
+/** Why search is (un)available — the honest status the UI and the tool
+ *  layer explain from. `engine` is the ACTIVE engine when live. */
+export interface SearchStatus {
+	available: boolean;
+	/** The active engine (null when unavailable). */
+	engine: SearchEngineId | null;
+	/** The one-line reason for the state (status text for the UI). */
+	reason: string;
+}

src/core/settings-resolution.ts

@@ -24,6 +24,7 @@
 
 import type { ThinkingLevel } from "@earendil-works/pi-agent-core";
 import type { ChatSettings } from "./contracts/chat.ts";
+import type { SearchEngineId } from "./search.ts";
 import {
 	BACKGROUND_MODEL_ROLES,
 	FACTORY_SETTINGS,
@@ -62,6 +63,10 @@ export interface EffectiveSettings {
 		tools: Record<string, boolean>;
 		/** Delta map as stored — absent key → override off. */
 		prompts: Record<string, boolean>;
+		/** The search-engine preference as stored (search wave, 2026-09-20):
+		 *  passthrough delta — engine resolution (pin → auto → unavailable)
+		 *  lives in server/search.ts, where keys are visible. */
+		search: { engine?: SearchEngineId };
 	};
 	appearance: EffectiveAppearance;
 	graph: Required<GraphSettings>;
@@ -105,6 +110,7 @@ export function resolveSettings(record: UserSettings | null, factory: ModelRoleS
 			models,
 			tools: agent.tools ?? {},
 			prompts: agent.prompts ?? {},
+			search: agent.search ?? {},
 		},
 		appearance: {
 			mode: appearance.mode ?? factoryAppearance.mode,

src/core/settings.ts

@@ -27,6 +27,7 @@
 
 import type { ThinkingLevel } from "@earendil-works/pi-agent-core";
 import type { ChatSettings } from "./contracts/chat.ts";
+import type { SearchEngineId } from "./search.ts";
 
 /** The schema version this code understands. Bump ONLY for breaking shape
  *  changes (a field renamed/meaning changed); pure additions never bump. */
@@ -70,6 +71,13 @@ export interface AgentSettings {
 	/** Tool toggles keyed by tool id (absent key = enabled). User-level
 	 *  only — no per-chat override (owner decision 2026-09-19). */
 	tools?: Record<string, boolean>;
+	/** Search-engine preference (search wave, 2026-09-20). OPTIONAL by
+	 *  owner decision: setting a key auto-activates its engine — the user
+	 *  never chooses an engine to make search work. An explicit choice only
+	 *  pins the preference (e.g. when BOTH keys are present); the chosen
+	 *  engine must still have its key, else search is honestly unavailable.
+	 *  Absent + no key = unavailable (no silent fallback, no default). */
+	search?: { engine?: SearchEngineId };
 	/** System-prompt override SWITCHES keyed by segment path (absent key =
 	 *  off). Switch-on requires the override file to exist (enforced by the
 	 *  route); the switch is explicit so users keep a file on disk but run
@@ -261,6 +269,13 @@ function sanitizeAgent(raw: Record<string, unknown>): AgentSettings {
 	if (tools) out.tools = tools;
 	const prompts = sanitizeBooleanMap(raw.prompts);
 	if (prompts) out.prompts = prompts;
+	// Search preference: lenient read side (an unknown engine id drops;
+	// the write side's parser is strict — a stale client can't brick the
+	// record, it just loses the pin and auto-detection resumes).
+	if (raw.search !== null && typeof raw.search === "object" && !Array.isArray(raw.search)) {
+		const engine = (raw.search as Record<string, unknown>).engine;
+		if (engine === "tavily" || engine === "brave") out.search = { engine };
+	}
 	return out;
 }
 

src/server/index.ts

@@ -32,6 +32,7 @@ export { effectivePromptSegments, allSegmentPaths, readPromptOverride } from "..
 // 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 * from "./search.ts";
 export { authStore } from "../store/auth.ts";
 export * from "./settings-body.ts";
 export * from "./turn-liveness.ts";

src/server/search.ts

@@ -0,0 +1,189 @@
+/**
+ * The search engines' server composition (search port + model slots wave,
+ * 2026-09-20): the Tavily + Brave adapters behind the core port
+ * (core/search.ts) + the live-engine resolution the settings UI and the
+ * agent-layer tool both read.
+ *
+ * Owner decisions (2026-09-20) baked in:
+ *  - NO default engine: an engine is live iff its key is present (auth
+ *    store or env — env wins, keyed via server/keys.ts keyValue).
+ *  - Setting a key is ALL the user does — auto-detection: explicit
+ *    agent.search.engine pins the preference (when BOTH keys are present
+ *    the preference order is Tavily → Brave); without a pin, whichever
+ *    engine has a key is the engine.
+ *  - An explicit choice does NOT silently fall back to the other engine:
+ *    engine pinned but its key missing = honestly unavailable (reason
+ *    says so) — no guessing what the user meant.
+ *
+ * The adapters are injected dependencies (fetch-shaped) so the agent-layer
+ * tool depends on the PORT only and tests never touch the network.
+ */
+
+import type { SearchEngineId, SearchHit, SearchProvider, SearchStatus } from "../core/search.ts";
+import { keyValue } from "./keys.ts";
+import { effectiveSettings } from "./stores.ts";
+
+/** The wire-callable shape the adapters close over (tests inject a stub). */
+type FetchLike = (input: string, init: RequestInit) => Promise<Response>;
+
+/** Tavily: POST https://api.tavily.com/search — Bearer auth in the
+ *  Authorization header (the current documented scheme; the legacy
+ *  api_key-in-body form is retired), query + max_results (0–20) in the
+ *  JSON body. VERIFIED against docs.tavily.com's OpenAPI, 2026-09-20:
+ *  response {results: [{title, url, content, score, …}]}, errors
+ *  {detail: {error}}. */
+export function tavilyProvider(apiKey: string, fetchFn: FetchLike = fetch): SearchProvider {
+	return {
+		id: "tavily",
+		async search(query: string, count: number): Promise<SearchHit[]> {
+			const resp = await fetchFn("https://api.tavily.com/search", {
+				method: "POST",
+				headers: {
+					"content-type": "application/json",
+					authorization: `Bearer ${apiKey}`,
+				},
+				body: JSON.stringify({ query, max_results: Math.min(count, 20) }),
+				signal: AbortSignal.timeout(30_000),
+			});
+			if (!resp.ok) {
+				const body = await resp.text();
+				// Their error body is {detail: {error: "…"}} — surface the
+				// message when present, else the raw slice.
+				let detail = body.slice(0, 200);
+				try {
+					const parsed = JSON.parse(body) as { detail?: { error?: string } };
+					if (parsed.detail?.error) detail = parsed.detail.error.slice(0, 200);
+				} catch {
+					/* keep the raw slice */
+				}
+				throw new Error(`Tavily search API ${resp.status}: ${detail}`);
+			}
+			const data = (await resp.json()) as {
+				results?: Array<{ title?: string; url?: string; content?: string }>;
+			};
+			return (data.results ?? [])
+				.filter((r) => typeof r.url === "string" && r.url)
+				.map((r) => ({
+					title: r.title ?? r.url ?? "",
+					url: r.url ?? "",
+					snippet: (r.content ?? "").replace(/\n/g, " ").slice(0, 500),
+				}));
+		},
+	};
+}
+
+/** Brave: GET https://api.search.brave.com/res/v1/web/search with the
+ *  key in the X-Subscription-Token header. VERIFIED against Brave's
+ *  dashboard docs, 2026-09-20: count max 20; response
+ *  {web: {results: [{title, url, description, …}]}}. */
+export function braveProvider(apiKey: string, fetchFn: FetchLike = fetch): SearchProvider {
+	return {
+		id: "brave",
+		async search(query: string, count: number): Promise<SearchHit[]> {
+			const url = new URL("https://api.search.brave.com/res/v1/web/search");
+			url.searchParams.set("q", query);
+			url.searchParams.set("count", String(Math.min(count, 20)));
+			const resp = await fetchFn(url.toString(), {
+				headers: {
+					accept: "application/json",
+					"x-subscription-token": apiKey,
+				},
+				signal: AbortSignal.timeout(30_000),
+			});
+			if (!resp.ok) {
+				const body = await resp.text();
+				throw new Error(`Brave search API ${resp.status}: ${body.slice(0, 200)}`);
+			}
+			const data = (await resp.json()) as {
+				web?: { results?: Array<{ title?: string; url?: string; description?: string }> };
+			};
+			return (data.web?.results ?? [])
+				.filter((r) => typeof r.url === "string" && r.url)
+				.map((r) => ({
+					title: r.title ?? r.url ?? "",
+					url: r.url ?? "",
+					snippet: (r.description ?? "").replace(/\n/g, " ").slice(0, 500),
+				}));
+		},
+	};
+}
+
+/** The engines this wave ships, in PREFERENCE order (both keys present,
+ *  no explicit pin → the first live engine wins; owner decision
+ *  2026-09-20: Tavily first — the AI-native search API the wave chose). */
+const ENGINE_ORDER: ReadonlyArray<{ id: SearchEngineId; envVar: string }> = [
+	{ id: "tavily", envVar: "TAVILY_API_KEY" },
+	{ id: "brave", envVar: "BRAVE_API_KEY" },
+];
+
+/** The engine's key (env-or-file; env wins) — null when the engine is
+ *  not keyed, which by owner decision means NOT LIVE. */
+function engineKey(id: SearchEngineId): string | null {
+	const envVar = ENGINE_ORDER.find((e) => e.id === id)?.envVar;
+	const value = envVar ? keyValue(envVar) : undefined;
+	return value ? value : null;
+}
+
+/** Resolve the search state PURELY from the given pins (testable): the
+ *  explicit engine (if pinned) wins but must be keyed; absent pin → first
+ *  keyed engine in preference order. Never throws. */
+export function resolveSearchEngineFor(
+	pinned: SearchEngineId | undefined,
+	/** Per-engine live keys (absent engine = absent property is fine). */
+	keys: Partial<Record<SearchEngineId, string | undefined>>,
+): SearchStatus & { key: string | null } {
+	const pinnedKey = pinned ? keys[pinned] ?? null : null;
+	if (pinned) {
+		if (!pinnedKey) {
+			return {
+				available: false,
+				engine: null,
+				reason: `search engine is set to "${pinned}" but its API key is missing — set the ${pinned === "tavily" ? "TAVILY_API_KEY" : "BRAVE_API_KEY"} key`,
+				key: null,
+			};
+		}
+		return { available: true, engine: pinned, reason: `search engine: ${pinned} (chosen)`, key: pinnedKey };
+	}
+	for (const { id } of ENGINE_ORDER) {
+		const key = keys[id] ?? null;
+		if (key) return { available: true, engine: id, reason: `search engine: ${id} (auto)`, key };
+	}
+	return {
+		available: false,
+		engine: null,
+		reason: "no search engine configured — set a Tavily or Brave search API key",
+		key: null,
+	};
+}
+
+/** The live search state (the honest availability signal): reads the
+ *  settings record's pin + the auth store fresh each call, so a key saved
+ *  mid-session activates on the next check (no restart). */
+export function searchStatus(): SearchStatus {
+	const { available, engine, reason } = resolveSearchEngineFor(
+		effectiveSettings().agent.search?.engine,
+		{
+			tavily: engineKey("tavily") ?? undefined,
+			brave: engineKey("brave") ?? undefined,
+		},
+	);
+	return { available, engine, reason };
+}
+
+/** Search available at all? (the settings UI's gray-out signal + the
+ *  researcher's enable/disable pin — Teacher stream's rewiring reads this.) */
+export function searchAvailable(): boolean {
+	return searchStatus().available;
+}
+
+/** The LIVE adapter, or null when unavailable. Composed fresh each call —
+ *  the tool layer (Teacher stream) calls this once per search, so key
+ *  rotations take effect immediately. */
+export function searchProvider(): SearchProvider | null {
+	const resolved = resolveSearchEngineFor(effectiveSettings().agent.search?.engine, {
+		tavily: engineKey("tavily") ?? undefined,
+		brave: engineKey("brave") ?? undefined,
+	});
+	if (!resolved.available || !resolved.key) return null;
+	return resolved.engine === "tavily" ? tavilyProvider(resolved.key) : braveProvider(resolved.key);
+}

src/server/settings-body.ts

@@ -184,6 +184,16 @@ export function parseAgentSettingsBody(body: unknown): SettingsBodyResult<AgentS
 	const prompts = parseBooleanMap(raw.prompts, "prompts");
 	if (prompts.error) return { ok: false, error: prompts.error };
 	if (prompts.map) settings.prompts = prompts.map;
+	if (raw.search !== undefined) {
+		const search = asRecord(raw.search);
+		if (!search) return { ok: false, error: "search must be an object" };
+		if (search.engine !== undefined) {
+			if (search.engine !== "tavily" && search.engine !== "brave") {
+				return { ok: false, error: 'search.engine must be "tavily" or "brave"' };
+			}
+			settings.search = { engine: search.engine };
+		}
+	}
 	return { ok: true, settings };
 }