feat(journeys): cross-app hops — exits-app / enters-at edges (B9)

Close the B9 gap (cross-app hops were catalogued under Phase 3 but never built):

- New ExternalNode + `exits-app` / `enters-at` edge kinds.
- exits-app: navigate / window.open / window.location.assign|replace, and
  `<a href>` / `<Link to>`, to an absolute/protocol-relative URL or a
  mailto:/tel:/sms: scheme → an edge to an external destination (deduped by
  host). OAuth redirects, payment gateways, and email links all leave the app.
- enters-at: deep-link / OAuth-callback route paths (/auth/…, /callback, oauth,
  sso, …) → an edge from an inbound external node.
- journeys() renders app-exits as a terminal `exit` step; CLI glyph ⏏.

Schema regenerated (external node kind + two edge kinds). New `externals` eval
check + fixture b9-cross-app-hops (Google OAuth, Stripe window.open, mailto,
/auth/callback). 41 core + 3 vision + 105 parser tests pass; eval green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: DeepCodeWork

TRACKER.md

@@ -214,6 +214,11 @@ The heart of the project. C1 and B1 live here.
 **Build:** feature-flag detection (configurable call names: `useFlag`, `useFeature`, `isEnabled`) and role checks in render branches → `EdgeCondition{kind:"flag"|"role"}` on the enclosed `renders`/`handles` edges.
 **Accept:** fixture `g5-feature-flag` green: flag-gated UI's journey step carries the flag name. **Gate 3 passes.**
 
+### [x] 3.6 Cross-app hops (added — was a catalog gap)
+**Failure modes:** B9
+**Build:** `ExternalNode` + `exits-app` / `enters-at` edges. Navigate/`window.open`/`window.location.assign`/`<a href>`/`<Link to>` to an absolute URL or `mailto:`/`tel:` scheme → `exits-app` (event or component → external, deduped by host). Deep-link/OAuth-callback route paths → `enters-at` from an inbound external node. Journeys reaching an external end with an `exit` step.
+**Accept:** fixture `b9-cross-app-hops` green (OAuth redirect, Stripe `window.open`, mailto link, `/auth/callback` entry).
+
 ---
 
 ## Phase 4 — Matching engine

eval/fixtures/b9-cross-app-hops/app/CallbackPage.tsx

@@ -0,0 +1,3 @@
+export function CallbackPage() {
+  return <p>Completing sign-in…</p>;
+}

eval/fixtures/b9-cross-app-hops/app/CheckoutPage.tsx

@@ -0,0 +1,11 @@
+export function CheckoutPage() {
+  // Payment gateway — an outbound hop to Stripe.
+  const pay = () => window.open("https://checkout.stripe.com/pay");
+
+  return (
+    <div>
+      <h1>Checkout</h1>
+      <button onClick={pay}>Pay now</button>
+    </div>
+  );
+}

eval/fixtures/b9-cross-app-hops/app/LoginPage.tsx

@@ -0,0 +1,13 @@
+export function LoginPage() {
+  // OAuth redirect — the journey leaves the app for the provider.
+  const loginWithGoogle = () =>
+    window.location.assign("https://accounts.google.com/o/oauth2/auth");
+
+  return (
+    <div>
+      <h1>Sign in</h1>
+      <button onClick={loginWithGoogle}>Continue with Google</button>
+      <a href="mailto:support@example.com">Contact support</a>
+    </div>
+  );
+}

eval/fixtures/b9-cross-app-hops/app/routes.tsx

@@ -0,0 +1,11 @@
+import { createBrowserRouter } from "react-router-dom";
+
+import { CallbackPage } from "./CallbackPage";
+import { CheckoutPage } from "./CheckoutPage";
+import { LoginPage } from "./LoginPage";
+
+export const router = createBrowserRouter([
+  { path: "/login", element: <LoginPage /> },
+  { path: "/checkout", element: <CheckoutPage /> },
+  { path: "/auth/callback", element: <CallbackPage /> },
+]);

eval/fixtures/b9-cross-app-hops/golden.json

@@ -0,0 +1,22 @@
+{
+  "failureMode": "B9",
+  "note": "Cross-app hops: an OAuth redirect (window.location.assign), a payment gateway (window.open), and a mailto link all leave the app → exits-app edges to external destinations; an /auth/callback route is an inbound entry point → an enters-at edge. Journeys that reach an external end with an 'exit' step.",
+  "expect": {
+    "components": [
+      { "name": "LoginPage", "instances": 0 },
+      { "name": "CheckoutPage", "instances": 0 },
+      { "name": "CallbackPage", "instances": 0 }
+    ],
+    "routes": [
+      { "path": "/login", "component": "LoginPage" },
+      { "path": "/checkout", "component": "CheckoutPage" },
+      { "path": "/auth/callback", "component": "CallbackPage" }
+    ],
+    "externals": [
+      { "kind": "exits", "component": "LoginPage", "host": "accounts.google.com" },
+      { "kind": "exits", "component": "LoginPage", "host": "mailto" },
+      { "kind": "exits", "component": "CheckoutPage", "host": "checkout.stripe.com" },
+      { "kind": "enters", "route": "/auth/callback", "host": "inbound" }
+    ]
+  }
+}

eval/src/checks.ts

@@ -222,6 +222,47 @@ export function runChecks(
     );
   }
 
+  for (const expected of golden.expect.externals ?? []) {
+    const id = `external:${expected.kind}:${expected.component ?? expected.route}~${expected.host}`;
+    const node = (nid: string) => graph.nodes.find((n) => n.id === nid);
+    let matched = false;
+    if (expected.kind === "exits") {
+      const owner = graph.nodes.find((n) => n.kind === "component" && n.name === expected.component);
+      matched = graph.edges.some((e) => {
+        if (e.kind !== "exits-app") return false;
+        const target = node(e.to);
+        if (target?.kind !== "external" || target.host !== expected.host || owner === undefined) {
+          return false;
+        }
+        if (e.from === owner.id) return true; // direct <a href>
+        // otherwise an event handled by the owner component
+        return (
+          node(e.from)?.kind === "event" &&
+          graph.edges.some((h) => h.kind === "handles" && h.from === owner.id && h.to === e.from)
+        );
+      });
+    } else {
+      matched = graph.edges.some((e) => {
+        if (e.kind !== "enters-at") return false;
+        const route = node(e.to);
+        const from = node(e.from);
+        return (
+          route?.kind === "route" &&
+          route.path === expected.route &&
+          from?.kind === "external" &&
+          from.host === expected.host
+        );
+      });
+    }
+    finalize(
+      "externals",
+      id,
+      matched,
+      expected.expectedFail,
+      matched ? undefined : `no ${expected.kind}-app edge for ${expected.host}`,
+    );
+  }
+
   for (const query of golden.expect.queries ?? []) {
     const id = `query:${query.terms.join("+") || JSON.stringify(query.structure)}`;
     const result = matchComponents(graph, {

eval/src/golden.ts

@@ -104,6 +104,18 @@ export interface GoldenCondition {
   expectedFail?: string;
 }
 
+/** A cross-app hop (step B9): an exits-app or enters-at edge. */
+export interface GoldenExternal {
+  kind: "exits" | "enters";
+  /** exits: the component whose link/handler leaves the app. */
+  component?: string;
+  /** enters: the inbound entry route path. */
+  route?: string;
+  /** External host/scheme the edge connects to (accounts.google.com, mailto, inbound). */
+  host: string;
+  expectedFail?: string;
+}
+
 export interface Golden {
   failureMode: string;
   note?: string;
@@ -129,6 +141,8 @@ export interface Golden {
     journeys?: GoldenJourney[];
     /** Flag/role conditions on renders/handles edges (step 3.5). */
     conditions?: GoldenCondition[];
+    /** Cross-app hops (B9): exits-app / enters-at edges. */
+    externals?: GoldenExternal[];
   };
 }
 
@@ -145,7 +159,8 @@ export interface CheckResult {
     | "routes"
     | "effects"
     | "journeys"
-    | "conditions";
+    | "conditions"
+    | "externals";
   status: CheckStatus;
   detail?: string;
 }

packages/cli/src/index.ts

@@ -195,6 +195,7 @@ const STEP_ARROW: Record<string, string> = {
   navigate: "→",
   fetch: "⇢",
   "state-write": "✎",
+  exit: "⏏",
 };
 
 function printJourneyPath(path: JourneyPath): void {

packages/core/src/query.ts

@@ -528,7 +528,7 @@ export function traceLineage(graph: LineageGraph, id: string): QueryResult<Linea
   return ok([{ value: lineage, confidence: confidenceFromScore(0.9), evidence }]);
 }
 
-export type JourneyStepKind = "page" | "event" | "navigate" | "fetch" | "state-write";
+export type JourneyStepKind = "page" | "event" | "navigate" | "fetch" | "state-write" | "exit";
 
 /** One node on a user-journey path, with the condition (if any) that gated it. */
 export interface JourneyStep {
@@ -711,14 +711,20 @@ export function journeys(
             ...(stepCondition ? { condition: stepCondition } : {}),
           };
           expand(page.componentId, page.label, [...pagePath, eventStep, navStep], nextVisited);
-        } else if (effect.kind === "triggers" || effect.kind === "writes-state") {
+        } else if (
+          effect.kind === "triggers" ||
+          effect.kind === "writes-state" ||
+          effect.kind === "exits-app"
+        ) {
           const target = byId.get(effect.to);
           if (target === undefined) continue;
           branched = true;
           const leaf: JourneyStep =
             target.kind === "data-source"
               ? { kind: "fetch", nodeId: target.id, label: target.endpoint, loc: target.loc }
-              : { kind: "state-write", nodeId: target.id, label: target.name, loc: target.loc };
+              : target.kind === "external"
+                ? { kind: "exit", nodeId: target.id, label: target.host, loc: target.loc }
+                : { kind: "state-write", nodeId: target.id, label: target.name, loc: target.loc };
           if (paths.length >= maxPaths) {
             truncated = true;
             return;