Make goal 2 cover a value we could not send as the caller wrote it

README.md

@@ -657,7 +657,8 @@ one wins. They do not override the hard rules below.
    is reported as undetermined rather than guessed; a report the peer marked as not final settles
    nothing, so nothing the library concludes may rest on one; a request the peer may already have
    taken is never re-sent on the library's own initiative; work the peer has no reason to send again
-   is not dropped.
+   is not dropped; a call that reports a message as sent asserts that the wire carried what the caller
+   wrote, so a value we cannot send as given is refused before anything goes out.
 3. **Strict in what we send, generous in what we read.** The library's own senders follow 3.4, and
    the codec parses whatever arrives. Where the letter of the spec would discard traffic a real SMSC
    sends, keep the traffic.

todo.md

@@ -189,17 +189,6 @@ and is also what the panel ranked hardest — two methods, one answer.
 
 ### Correctness, ahead of everything below
 
-- [ ] **Take the maintainer's call on whether goal 2 covers a value we could not send as given.**
-      Goal 2's four clauses are one family — an undeterminable outcome, a non-final report, a
-      re-send, dropped work — and none of them covers *the wire carried a value the caller did not
-      write, and the call reported success*, which is the `NaN` sender, the `sm_length: 0` body and
-      `1e+21`. Items below cite goal 2 for exactly that, and the DLR-merge item concedes it "is
-      stated in no file today either way". Proposed clause, after "…is not dropped": "; a call that
-      reports a message as sent asserts that the wire carried what the caller wrote, so a value we
-      cannot send as given is refused before anything goes out rather than coerced into one the
-      caller never wrote." A goal is the maintainer's, so nothing edits README until that is
-      answered. From the prose pass of #18.
-
 - [ ] **Range-check `maxOctets` with its five siblings.** `limitsOf()` in `session-options.ts`
       covers `idleTimeout`, `maxOutstanding`, `maxReassembly`, `reassemblyTimeout`, `responseTimeout`
       and `shutdownTimeout`; `maxOctets` is documented, consumed by `Reassembler`, and absent from