Ask the client library not to narrate every login

CHANGELOG.md

@@ -7,6 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- **The GemDB Shell no longer prints the database client's own chatter.**
+  Opening a shell wrote a line like
+  `gcits login: session 0x… lgc 0x… rpc gem processId 4726` onto your terminal
+  between the banner and the first prompt, with a matching one on exit — the
+  client library narrating itself. Every session GemDB opens now asks it not
+  to.
+
 ## [1.2.0] - 2026-08-27
 
 A notebook is a unit of work again: each one gets its own database session, and

src/__integration__/repl.test.ts

@@ -162,6 +162,11 @@ send "exit()\\r"
     expect(ran.transcript).toContain('42');
     expect(ran.transcript).toContain('marco polo');
     expect(ran.transcript).toContain('KeyboardInterrupt');
+    // The client library narrates every login and logout on stdout unless the
+    // session asks it not to (GCI_LOGIN_QUIET, session.ts). This is the one
+    // place that shows: the shell's stdout is the user's terminal, so the
+    // chatter would land between the banner and the first prompt.
+    expect(ran.transcript).not.toContain('gcits');
     expect(ran.code).toBe(0);
     expect(isRunning()).toBe(true); // the shell brought the stone up itself
   });

src/session.ts

@@ -48,6 +48,23 @@ export class SessionLimitError extends SessionError {}
  */
 const SESSION_LIMIT_ERRORS = new Set([4039, 4041, 4050]);
 
+/**
+ * `GCI_LOGIN_QUIET` — stop the client library narrating each login on stdout.
+ *
+ * Without it every login writes a line like
+ * `gcits login: session 0x… lgc 0x… rpc gem processId 4726` (and a matching
+ * one at logout) to the process's real stdout, from inside the C library. In
+ * the extension host that is merely noise in the log; in a GemDB Shell it is
+ * printed straight onto the user's terminal, and in `gemdb -c` it lands in
+ * output a script may be piping somewhere.
+ *
+ * Defined here rather than in `gci/gciConstants.ts` because that directory is
+ * vendored from Jasper byte-for-byte and carries no login flags at all. The
+ * value is from the engine's own `include/gci.ht` (`GCI_LOGIN_QUIET = 0x10`,
+ * in the flag enum `GciTsLogin`'s `loginFlags` takes).
+ */
+const GCI_LOGIN_QUIET = 0x10;
+
 /** What kind of user interface a session belongs to. */
 export type SessionKind = 'notebook' | 'shell' | 'extension';
 
@@ -400,7 +417,7 @@ export class GciSession {
       gemNrs(),
       DB_USER,
       DB_PASSWORD,
-      0,
+      GCI_LOGIN_QUIET,
       0,
     );
     if (!result.session) {