Fold the session's closed and ended flags into one link state, and split Locality by the scoring run

AGENTS.md

@@ -87,8 +87,8 @@ src/
 ```
 
 Imports point one way: `defs` knows nothing above it but `result.ts`, `pdu` uses `defs`, `session`
-uses `pdu`, and `client`/`server` use `session`. The one way back up is the `Session` handed to
-`createSms()`, imported as a type only.
+uses `pdu`, and `client`/`server` use `session`. The ways back up are the `Session` handed to
+`createSms()` and to the hooks `session-options.ts` types, both imported as a type only.
 
 **Parameter order is wire order.** The key order inside `cmds.*.params` is the order the fields are
 written to and read from the buffer. Never sort those alphabetically — the alphabetical-ordering

src/session.ts

@@ -72,8 +72,8 @@ export class Session extends EventEmitter<SessionEvents> {
 	private readonly timers: LinkTimers;
 	private readonly transport: PduTransport;
 
-	private closed = false;
-	private ended = false;
+	/** `torn-down` goes back to `attached` when the reconnect loop brings a link up. */
+	private link: 'attached' | 'ended' | 'torn-down' = 'attached';
 
 	/** A listener that throws is the application's bug; it must not become ours. Hard rule 1. */
 	override emit<K extends keyof SessionEvents>(
@@ -186,7 +186,7 @@ export class Session extends EventEmitter<SessionEvents> {
 		const sent = built.err ? { err: built.err } : this.transport.write(built.buffer);
 
 		// A peer that unbinds and drops the link takes our response with it; that is not a failure.
-		if (sent.err && !this.closed) {
+		if (sent.err && this.link === 'attached') {
 			this.log.warn('session - could not answer a request', {
 				cmdName,
 				message: sent.err.message,
@@ -221,12 +221,12 @@ export class Session extends EventEmitter<SessionEvents> {
 	 */
 	async unbind(): Promise<VoidResult> {
 		const drained = await this.drain(undefined);
-		const wasOpen = !this.closed;
+		const wasOpen = this.link === 'attached';
 		// now(), not send(): a drain refuses a send, and the unbind goes out either way.
 		const sent = wasOpen
 			? await this.outgoing.now({ cmdName: 'unbind' })
 			: { err: new Error('Session is closed') };
-		const closedOnUnbind = wasOpen && this.closed;
+		const closedOnUnbind = wasOpen && this.link !== 'attached';
 
 		this.end();
 
@@ -325,7 +325,7 @@ export class Session extends EventEmitter<SessionEvents> {
 
 	private attach(sock: Socket): void {
 		this.transport.attach(sock);
-		this.closed = false;
+		this.link = 'attached';
 	}
 
 	/** Stops new sends and waits out the messages we hold and the requests already issued. */
@@ -371,17 +371,17 @@ export class Session extends EventEmitter<SessionEvents> {
 	}
 
 	private emitClose(): void {
-		if (this.ended) return;
+		if (this.link === 'ended') return;
 
-		this.ended = true;
+		this.link = 'ended';
 		this.outgoing.linkLost(false);
 		this.emit('close');
 	}
 
 	private teardown(): void {
-		if (this.closed) return;
+		if (this.link !== 'attached') return;
 
-		this.closed = true;
+		this.link = 'torn-down';
 
 		// Read once: clear() reports lost segments, and a listener could stop the loop between reads.
 		const retrying = this.retrying();
@@ -445,15 +445,15 @@ export class Session extends EventEmitter<SessionEvents> {
 	}
 
 	private resetTimers(): void {
-		if (this.closed) return;
+		if (this.link !== 'attached') return;
 
 		this.timers.reset();
 	}
 
 	private onClose(): void {
-		if (this.reconnectLoop && !this.reconnectLoop.isStopped()) {
+		if (this.retrying()) {
 			this.teardown();
-			this.reconnectLoop.schedule();
+			this.reconnectLoop?.schedule();
 
 			return;
 		}

todo.md

@@ -199,9 +199,24 @@ next work ([decision](docs/decisions.md#internals-and-tests)).
 
 ### Locality — next, ahead of everything below; 5–6 today, and the gate is 7
 
-- [ ] **Lift the held-message and shutdown code to Locality 7, and confirm it with a scoring run.**
-      The 2026-09-27 run capped every seat there; a run reading 7.0 or above also retires the #30
-      decision.
+A second four-seat run on 2026-09-28, after #35–#40, read 6, 6, 7 and 6 again, Locality 5, 5, 6
+and 5. Every seat ranked the session's lifecycle hardest and least wanted to modify it.
+
+- [ ] **Lift Locality to 7, and confirm it with a scoring run.** A run reading 7.0 or above also
+      retires the #30 decision. The sub-items are what the 2026-09-28 run named, most seats first.
+- [ ] **Let `Session` own its bind state.** `client.ts` and `server.ts` write `boundAs`, `loggedIn`
+      and `peerInterfaceVersion` onto the session from outside, and `loggedIn` duplicates
+      `boundAs !== undefined`. A method such as `session.bound(bindType, declaredVersion)` with the
+      three fields read-only changes the public surface a hand-wired SMSC uses, so it needs the
+      maintainer's call first. All four seats.
+- [ ] **Name what `request()`, `carry()` and `now()` each skip.** Three ways onto the wire differ
+      only in which of the drain, the gate and the window they bypass, and none of the names says
+      which. Three seats.
+- [ ] **Give the held-message flow one place a reader can follow it.** Whether a drain still waits
+      on a message is spread over `emitSms()`, `MessageHold`, the session's rejection route and
+      `Sms.isHeld()`. Four seats.
+- [ ] **Shrink the `IncomingDeps` closure bag.** 16 lambdas, six of them repeated in
+      `SmsHandlers`, which makes every inbound call path indirect. Two seats.
 
 ### Correctness
 
@@ -244,6 +259,23 @@ next work ([decision](docs/decisions.md#internals-and-tests)).
       README.md or in MIGRATION.md — write it in the same change as the rule, so it is worded once.
       From the stability and product-owner reviews of #18.
 
+- [ ] **Build every error from a thrown value through `errorFrom()`.** `reconnect-loop.ts` (in
+      `run()`'s catch and in `bringUp()`) and `client.ts`'s connect still call `String(thrown)`,
+      which throws on a null-prototype object; in `run()` that lands as an unhandled rejection from
+      a `void`ed promise, against hard rule 1. From the 2026-09-28 scoring run.
+
+- [ ] **Leave `sms.smsId` alone when `sendResp()` fails.** `sms.ts` assigns `options.smsId` before
+      the lost-link check and before the write, so a failed answer still renames the message and a
+      later `sendDlr()` names an id the peer was never given. From the 2026-09-28 scoring run.
+
+- [ ] **Refuse a timeout past 2³¹−1 ms, as `connectTimeout` already is.** `checkLimits()` bounds
+      `responseTimeout`, `idleTimeout`, `shutdownTimeout` and `reassemblyTimeout` from below only,
+      and Node fires a larger delay after 1 ms. From the 2026-09-28 scoring run.
+
+- [ ] **Keep a bare ESC out of GSM detection.** `gsmRegex` in `defs/encodings.ts` admits `\x1B`,
+      so `"\x1B("` is detected as GSM, goes out as 0x1B 0x28 and arrives as `{`. From the
+      2026-09-28 scoring run.
+
 ### Throughput — goal 6, and the default window is where we are slowest
 
 - [ ] **Close the gap to jsmpp at `maxOutstanding: 10`.** Measured 2026-09-20 against the same sink,