Add an Atomic SDK harness for the hosted Planner

.env.example

@@ -6,14 +6,18 @@ DATABASE_URL=postgresql://chopin:chopin@127.0.0.1:5432/chopin?sslmode=disable
 AGENT=on
 # With HARNESS=pi, use an ID from Pi's catalog, preferably provider-qualified
 # (for example github-copilot/gpt-5.6-luna); Pi silently substitutes its default
-# model for an ID it does not know, including gpt-6-luna.
+# model for an ID it does not know, including gpt-6-luna. HARNESS=atomic requires
+# a provider/model ID from Atomic's catalog (for example
+# vercel-ai-gateway/anthropic/claude-sonnet-4.6) and fails a turn on any other.
 MODEL=gpt-6-luna
 HARNESS=copilot-sdk
 # Auth mode forwarded to the selected harness. The current copilot-sdk adapter
 # uses each owner's token and does not consume it. Host-login fallback modes
 # such as "auto" require SERVER_HOST to bind only to loopback. HARNESS=pi
 # requires this to be set explicitly (auto, openai, anthropic, custom, or
 # ai-gateway); only ai-gateway is allowed on a non-loopback SERVER_HOST.
+# HARNESS=atomic requires auto (the host's Atomic login and environment keys,
+# loopback only) or ai-gateway (AI_GATEWAY_API_KEY, any bind).
 #HARNESS_AUTH=
 BACKGROUND_JOBS=on
 WEB_RESEARCH=on

README.md

@@ -72,14 +72,15 @@ and tool vocabulary remain optimized for planning.
 - The first eligible person to invoke the Planner or start a model-backed
   research request supplies the GitHub App user token used for that channel
   and, under the default `copilot-sdk` harness, the Copilot entitlement. With
-  `HARNESS=pi`, model access comes from the operator's `HARNESS_AUTH` instead.
+  `HARNESS=pi` or `HARNESS=atomic`, model access comes from the operator's
+  `HARNESS_AUTH` instead.
   A server restart clears every session and releases that ownership. A
   returning browser in local device mode can restore a new session, but does
   not reclaim Planner ownership.
 - Document and Chat context, along with repository material selected by
   the Planner, is sent to the harness's model provider during a turn (GitHub
-  Copilot by default; under `HARNESS=pi`, the provider chosen by
-  `HARNESS_AUTH`). Model-backed background jobs also send job-specific private
+  Copilot by default; under `HARNESS=pi` or `HARNESS=atomic`, the provider
+  chosen by `HARNESS_AUTH`). Model-backed background jobs also send job-specific private
   material, including context loaded during execution, to isolated workers on
   the same harness. The public research worker receives
   only the exact submitted brief, but may derive or refine the queries it sends

apps/server/package.json

@@ -14,6 +14,7 @@
 		"@ai-sdk/harness-pi": "catalog:harness",
 		"@ai-sdk/mcp": "catalog:harness",
 		"@ai-sdk/sandbox-just-bash": "catalog:harness",
+		"@bastani/atomic": "catalog:harness",
 		"@earendil-works/pi-coding-agent": "catalog:harness",
 		"@chopin/dialect": "workspace:*",
 		"@chopin/protocol": "workspace:*",

apps/server/src/config.test.ts

@@ -113,6 +113,19 @@ describe("configuration", () => {
 			.toMatchObject({ harness: "pi", model: "openai/gpt-5.6" });
 	});
 
+	it("requires an explicit provider/model MODEL under the atomic harness", () => {
+		expect(() => configured({ HARNESS: "atomic", HARNESS_AUTH: "auto" }))
+			.toThrow("MODEL is required when HARNESS=atomic");
+		expect(configured({
+			HARNESS: "atomic",
+			HARNESS_AUTH: "ai-gateway",
+			MODEL: "vercel-ai-gateway/anthropic/claude-sonnet-4.6",
+		})).toMatchObject({
+			harness: "atomic",
+			model: "vercel-ai-gateway/anthropic/claude-sonnet-4.6",
+		});
+	});
+
 	it("requires a valid PostgreSQL URL", () => {
 		expect(() => configured({ DATABASE_URL: undefined })).toThrow("DATABASE_URL is required");
 		expect(() => configured({ DATABASE_URL: "https://database.test" })).toThrow("PostgreSQL URL");

apps/server/src/config.ts

@@ -48,12 +48,15 @@ export type Config = {
 const DEFAULT_PORT = 8787;
 const DEFAULT_MODEL = "gpt-6-luna";
 
-/** The default is a Copilot model ID. Pi resolves IDs against its own catalog,
- * so a Pi deployment must name its model rather than inherit one Pi lacks. */
+/** The default is a Copilot model ID. Pi and Atomic resolve IDs against their
+ * own catalogs, so those deployments must name a model rather than inherit one
+ * the catalog lacks. */
 function model(harness: string): string {
 	let configured = process.env.MODEL;
 	if (configured) return configured;
-	if (harness === "pi") throw new Error("MODEL is required when HARNESS=pi");
+	if (harness === "pi" || harness === "atomic") {
+		throw new Error(`MODEL is required when HARNESS=${harness}`);
+	}
 	return DEFAULT_MODEL;
 }
 export function harnessSelection(): Pick<Config, "host" | "harness" | "harnessAuth"> {