claude-code: the sealed hand-over, the credentials write with the lineage rule, the identity read (hq to-be 40 WP2, in progress)

The parts of the agent module that hold whichever way the console is registered: X25519 +
HKDF + AES-GCM from Node's own library so the bundle carries no dependency; the predecessor's
lineage rule (rotation only if newer, a re-issue adopted, a switch regardless) with its
incidents as tests; an atomic 0600 write that strips any refresh token and keeps keys it does not
know; the account read from the agent's own state file. Manifest and renderer follow.

modules/claude-code/identity.ts

@@ -0,0 +1,25 @@
+// Which account the agent is logged in as (novox/hq ADR 0183): not in the token, but in the agent's
+// own state file beside the home, `~/.claude.json` → `oauthAccount`. Read, never written.
+
+import { readFileSync } from "node:fs";
+
+export interface Identity {
+  readonly accountUuid: string;
+  readonly emailAddress?: string;
+  readonly organizationUuid?: string;
+}
+
+export function readIdentity(stateFile: string): Identity | null {
+  try {
+    const raw = JSON.parse(readFileSync(stateFile, "utf8")) as { oauthAccount?: Record<string, unknown> };
+    const a = raw.oauthAccount;
+    if (!a || typeof a.accountUuid !== "string") return null;
+    return {
+      accountUuid: a.accountUuid,
+      emailAddress: typeof a.emailAddress === "string" ? a.emailAddress : undefined,
+      organizationUuid: typeof a.organizationUuid === "string" ? a.organizationUuid : undefined,
+    };
+  } catch {
+    return null;
+  }
+}