measure(explore): the factory-closure envelope premise does not hold (CG-27)

CG-27 asked whether the >50%-of-file envelope drop should cover `function` / `method`, so a `createFoo()` factory returning an object of closures stops merging every closure inside it into one cluster. Measured on a hermetic fixture, it should not, and the issue is closed as obsolete with CG-30 credited. Two mechanisms already absorb the shape. shrinkCluster orders members by (importance desc, size ASC) and refuses any member that overruns the cap once something is kept, so a file-spanning member is only selected when it is the sole member of the top importance tier — eight of nine query shapes never selected it at all. When it IS selected, CG-30 windows it on whole lines, so the file still delivers bounded, readable source (6 of 9 closure definitions in that configuration). Dropping the range instead SPLITS the file, and only the first-chosen cluster may be shrunk: a trivial 7-line cluster won the density tiebreak and the answer-bearing cluster was dropped whole — rank-#1 file 7,539 chars and 7 of 11 closures to 397 and none. Reaching the same intent more carefully (defer the envelope MEMBER inside shrinkCluster, leaving clustering untouched) is noise: 69 vs 68 closure definitions across nine query shapes. Nothing shipped. Adds the fixture, the probe, a standing gate on the outcome, and the record — including a real defect the measurement exposed on the epic tip: django's query.py leaves 8,212 of 10,135 unspent and drops a score-290 cluster to keep a score-14 one. Filed separately. No behaviour change, so no CHANGELOG entry.
2026-08-06 14:07:22 -05:00
parent d49265043c
commit 91cb5b4317
4 changed files with 444 additions and 3 deletions
@@ -0,0 +1,148 @@
+import type { StoreDeps } from './types';
+import { joinPath, toQueryString } from '../lib/http';
+
+/**
+ * The session store — a factory closure and NOTHING else at file scope. No
+ * companion type alias, no tail helper, no exported constants: every other
+ * symbol in this file lives inside the closure. That shape matters, because it
+ * is the one where the enclosing range is the only top-importance symbol the
+ * file can offer a query.
+ */
+export function createSessionStore(deps: StoreDeps, baseUrl: string) {
+  const SESSION_ENDPOINT = '/api/session';
+  const REFRESH_SKEW_MS = 30_000;
+
+  let token: string | null = null;
+  let expiresAt = 0;
+  let profile: { id: string; email: string; roles: string[] } | null = null;
+  let refreshing: Promise<string | null> | null = null;
+  const auditLog: Array<{ at: number; event: string }> = [];
+
+  function record(event: string): void {
+    auditLog.push({ at: deps.now(), event });
+    if (auditLog.length > 200) auditLog.splice(0, auditLog.length - 200);
+  }
+
+  /** Exchange credentials for a session token and cache the profile. */
+  async function signIn(email: string, password: string): Promise<boolean> {
+    const url = joinPath(baseUrl, SESSION_ENDPOINT) + toQueryString({ email });
+    let payload: unknown;
+    try {
+      payload = await deps.fetchJson(url);
+    } catch (error) {
+      record(`signIn failed: ${error instanceof Error ? error.message : String(error)}`);
+      return false;
+    }
+    if (typeof payload !== 'object' || payload === null) {
+      record('signIn got a non-object payload');
+      return false;
+    }
+    const body = payload as { token?: string; expiresAt?: number; profile?: typeof profile };
+    if (typeof body.token !== 'string' || body.token.length === 0) {
+      record('signIn payload carried no token');
+      return false;
+    }
+    void password;
+    token = body.token;
+    expiresAt = typeof body.expiresAt === 'number' ? body.expiresAt : deps.now() + 3_600_000;
+    profile = body.profile ?? null;
+    record(`signIn ok for ${email}`);
+    return true;
+  }
+
+  /** Drop every trace of the session, locally and on the server. */
+  async function signOut(): Promise<void> {
+    if (token === null) return;
+    const url = joinPath(baseUrl, SESSION_ENDPOINT) + toQueryString({ action: 'revoke' });
+    try {
+      await deps.fetchJson(url);
+    } catch (error) {
+      record(`signOut revoke failed: ${error instanceof Error ? error.message : String(error)}`);
+    }
+    token = null;
+    expiresAt = 0;
+    profile = null;
+    refreshing = null;
+    record('signOut complete');
+  }
+
+  /**
+   * Renew the token before it expires. Concurrent callers share one in-flight
+   * request so a burst of requests cannot start a refresh storm.
+   */
+  async function refreshToken(): Promise<string | null> {
+    if (token === null) return null;
+    if (refreshing !== null) return refreshing;
+
+    refreshing = (async () => {
+      const url = joinPath(baseUrl, SESSION_ENDPOINT) + toQueryString({ action: 'refresh' });
+      try {
+        const payload = await deps.fetchJson(url);
+        const body = payload as { token?: string; expiresAt?: number };
+        if (typeof body?.token === 'string' && body.token.length > 0) {
+          token = body.token;
+          expiresAt = typeof body.expiresAt === 'number' ? body.expiresAt : deps.now() + 3_600_000;
+          record('refreshToken renewed the session');
+          return token;
+        }
+        record('refreshToken payload carried no token');
+        return null;
+      } catch (error) {
+        record(`refreshToken failed: ${error instanceof Error ? error.message : String(error)}`);
+        return null;
+      } finally {
+        refreshing = null;
+      }
+    })();
+
+    return refreshing;
+  }
+
+  /** The token to send with a request, renewing it first when it is close to expiry. */
+  async function authorize(): Promise<string | null> {
+    if (token === null) return null;
+    if (deps.now() + REFRESH_SKEW_MS < expiresAt) return token;
+    return refreshToken();
+  }
+
+  /** Does the signed-in user hold every one of these roles? */
+  function hasRoles(...required: string[]): boolean {
+    if (profile === null) return false;
+    const held = new Set(profile.roles);
+    for (const role of required) {
+      if (!held.has(role)) return false;
+    }
+    return true;
+  }
+
+  /** Seconds left on the session, floored at zero. */
+  function secondsRemaining(): number {
+    if (token === null) return 0;
+    return Math.max(0, Math.floor((expiresAt - deps.now()) / 1000));
+  }
+
+  /** The last N audit entries, newest first — what the account page renders. */
+  function recentActivity(limit = 20): Array<{ at: number; event: string }> {
+    return auditLog.slice(-limit).reverse();
+  }
+
+  function snapshot() {
+    return {
+      signedIn: token !== null,
+      email: profile?.email ?? null,
+      roles: profile?.roles ?? [],
+      secondsRemaining: secondsRemaining(),
+    };
+  }
+
+  return {
+    signIn,
+    signOut,
+    refreshToken,
+    authorize,
+    hasRoles,
+    secondsRemaining,
+    recentActivity,
+    snapshot,
+  };
+}