syntax: update to allow non-leading digits in NSID 'name' part (#3633)

* syntax: allow non-leading digits in NSID 'name' part

* update (copied) interop tests

* prettier

interop-test-files/syntax/aturi_syntax_valid.txt

@@ -32,3 +32,4 @@ at://did:abc:123/io.nsid.someFunc/-
 at://did:abc:123/io.nsid.someFunc/_
 at://did:abc:123/io.nsid.someFunc/~
 at://did:abc:123/io.nsid.someFunc/...
+at://did:plc:asdf123/com.atproto.feed.postV2

interop-test-files/syntax/nsid_syntax_invalid.txt

@@ -3,15 +3,13 @@ com.oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.foo
 com.example.oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
 com.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.foo
 
-# invliad examples
+# invalid examples
 com.example.foo.*
 com.example.foo.blah*
 com.example.foo.*blah
-com.example.f00
 com.exa💩ple.thing
 a-0.b-1.c-3
 a-0.b-1.c-o
-a0.b1.c3
 1.0.0.127.record
 0two.example.foo
 example.com
@@ -29,4 +27,4 @@ com.atproto.feed.p*st
 com.atproto.feed.po#t
 com.atproto.feed.p!ot
 com.example-.foo
-
+com.example.fooBar.2

interop-test-files/syntax/nsid_syntax_valid.txt

@@ -5,6 +5,7 @@ com.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle.middle
 
 # valid examples
 com.example.fooBar
+com.example.fooBarV2
 net.users.bob.ping
 a.b.c
 m.xn--masekowski-d0b.pl
@@ -18,6 +19,8 @@ test.12345.record
 a01.thing.record
 a.0.c
 xn--fiqs8s.xn--fiqa61au8b7zsevnm8ak20mc4a87e.record.two
+a0.b1.c3
+com.example.f00
 
 # allows onion (Tor) NSIDs
 onion.expyuzz4wqqyqhjn.spec.getThing

packages/syntax/src/nsid.ts

@@ -87,8 +87,10 @@ export const ensureValidNsid = (nsid: string): void => {
     if (/^[0-9]/.test(l) && i === 0) {
       throw new InvalidNsidError('NSID first part may not start with a digit')
     }
-    if (!/^[a-zA-Z]+$/.test(l) && i + 1 === labels.length) {
-      throw new InvalidNsidError('NSID name part must be only letters')
+    if (!/^[a-zA-Z][a-zA-Z0-9]*$/.test(l) && i + 1 === labels.length) {
+      throw new InvalidNsidError(
+        'NSID name part must be only letters and digits (and no leading digit)',
+      )
     }
   }
 }
@@ -97,7 +99,7 @@ export const ensureValidNsidRegex = (nsid: string): void => {
   // simple regex to enforce most constraints via just regex and length.
   // hand wrote this regex based on above constraints
   if (
-    !/^[a-zA-Z]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)+(\.[a-zA-Z]([a-zA-Z]{0,61}[a-zA-Z])?)$/.test(
+    !/^[a-zA-Z]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)+(\.[a-zA-Z]([a-zA-Z0-9]{0,62})?)$/.test(
       nsid,
     )
   ) {

packages/syntax/tests/nsid.test.ts

@@ -83,15 +83,15 @@ describe('NSID validation', () => {
     expectValid('a01.thing.record')
     expectValid('a.0.c')
     expectValid('xn--fiqs8s.xn--fiqa61au8b7zsevnm8ak20mc4a87e.record.two')
+    expectValid('a0.b1.c3')
+    expectValid('com.example.f00')
 
     expectInvalid('com.example.foo.*')
     expectInvalid('com.example.foo.blah*')
     expectInvalid('com.example.foo.*blah')
-    expectInvalid('com.example.f00')
     expectInvalid('com.exa💩ple.thing')
     expectInvalid('a-0.b-1.c-3')
     expectInvalid('a-0.b-1.c-o')
-    expectInvalid('a0.b1.c3')
     expectInvalid('1.0.0.127.record')
     expectInvalid('0two.example.foo')
     expectInvalid('example.com')