diff --git a/src/main/kotlin/graphql/kickstart/tools/SchemaClassScanner.kt b/src/main/kotlin/graphql/kickstart/tools/SchemaClassScanner.kt
index 5a63f30d..42f312e2 100644
--- a/src/main/kotlin/graphql/kickstart/tools/SchemaClassScanner.kt
+++ b/src/main/kotlin/graphql/kickstart/tools/SchemaClassScanner.kt
@@ -123,9 +123,6 @@ internal class SchemaClassScanner(
             handleDictionaryTypes(getAllObjectTypeMembersOfDiscoveredUnions()) { "Object type '${it.name}' is a member of a known union, but no class could be found for that type name.  Please pass a class for type '${it.name}' in the parser's dictionary." }
             if (scanQueue()) continue
 
-            // Look for unions and interfaces used only by interface fields last, so types that can be reached some other way
-            // are still discovered in the same order as before. With includeUnusedTypes the unused types loop below already
-            // picks these up one at a time, scanning in between, so leave that path unchanged.
             if (!options.includeUnusedTypes && handleInterfaceFieldTypes()) continue
 
             break
diff --git a/src/test/kotlin/graphql/kickstart/tools/CommentConventionsTest.kt b/src/test/kotlin/graphql/kickstart/tools/CommentConventionsTest.kt
new file mode 100644
index 00000000..318997d8
--- /dev/null
+++ b/src/test/kotlin/graphql/kickstart/tools/CommentConventionsTest.kt
@@ -0,0 +1,293 @@
+package graphql.kickstart.tools
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Assert.fail
+import org.junit.Test
+import java.io.File
+import java.time.LocalDate
+
+class CommentConventionsTest {
+
+    @Test
+    fun `comments carry no issue numbers, history or versions`() {
+        val sources = listOf(File("src/main"), File("src/test")).asSequence()
+            .flatMap { it.walkTopDown() }
+            .filter { it.isFile && it.extension in setOf("kt", "java") }
+            .sortedBy { it.path }
+            .toList()
+        assertTrue("no .kt or .java files under ${File("src").absolutePath}, run the test from the project root", sources.isNotEmpty())
+
+        val violations = sources.flatMap { CommentLint.check(it.path, it.readText(), LocalDate.now()) }
+        if (violations.isNotEmpty()) {
+            val lines = violations.distinctBy { it.path to it.line }.size
+            fail(violations.joinToString("\n", "${violations.size} comment convention violation(s) on $lines line(s):\n"))
+        }
+    }
+
+    private val today = LocalDate.of(2026, 11, 4)
+
+    private fun check(source: String, path: String = "Example.kt") = CommentLint.check(path, source, today)
+
+    private fun rules(source: String, path: String = "Example.kt") = check(source, path).map { it.rule }
+
+    private fun markerFix(source: String) = check(source).single { it.rule == "lint-allow" }.fix
+
+    @Test
+    fun `lint flags issue numbers, history and versions in whole comment blocks`() {
+        assertEquals(listOf("history"), rules("/* this used to\n * be slow */"))
+        assertEquals(listOf("history"), rules("// this used to\n// be slow"))
+        assertEquals(listOf("issue-number"), rules("// see #999"))
+        assertEquals(listOf("issue-number"), rules("// the enum and directive from issue #823"))
+        assertEquals(listOf("issue-number"), rules("// from https://github.com/o/r/issues/424"))
+        assertEquals(listOf("issue-number", "history"), rules("// built as the type before #552"))
+        assertEquals(listOf("history"), rules("// in the same order as before"))
+        assertEquals(listOf("history", "history"), rules("// converted, as it did before this check"))
+        assertEquals(listOf("history"), rules("// to keep those schemas building"))
+        assertEquals(listOf("history"), rules("// so those schemas keep building"))
+        assertEquals(listOf("history"), rules("// keeps building old schemas"))
+        assertEquals(listOf("history"), rules("// so schemas keep building"))
+        assertEquals(listOf("history"), rules("// the old behavior was to throw here"))
+        assertEquals(listOf("history"), rules("// restores the previous behaviour"))
+        assertEquals(listOf("history"), rules("// this check is no longer needed"))
+        assertEquals(listOf("version"), rules("/** @since 15.0 */"))
+        assertEquals(listOf("version"), rules("// since 1.2.0 the parser"))
+        assertTrue(check("// see #999 as before, since 1.2.0").all { "lint-allow" in it.fix })
+    }
+
+    @Test
+    fun `lint leaves ordinary prose, code and other languages' syntax alone`() {
+        listOf(
+            "// returns the list unchanged",
+            "// the previously resolved type wins",
+            "// the cache used to build the type in the scanner",
+            "// no longer than 80 characters",
+            "// the result is now cached for the next call",
+            "// so the loop keeps working on an empty map",
+            "// step #1 builds the dictionary",
+            "// the border is #000000 and the text is #fff",
+            "// waits since 2.5 seconds have passed",
+            "// explains the lint-allow marker syntax for readers",
+            "// https://example.com/docs/#123",
+            "// TODO reject in 16.0.0 (#999)",
+            "val s = \"// see #999\"",
+        ).forEach { assertEquals(it, emptyList<String>(), rules(it)) }
+
+        assertEquals(listOf("issue-number"), rules("/* a /* b */\nString s = \"no longer needed\"; // see #13", "Example.java"))
+        assertEquals(listOf("issue-number"), rules("String s = \"\"\"\n  \\\"\"\" // #1\n  \"\"\"; // see #2", "Example.java"))
+    }
+
+    @Test
+    fun `lint honors only valid markers and says why a marker is invalid`() {
+        assertEquals(emptyList<String>(), rules("// as before lint-allow history until 2026-12-01 by oryan: domain term"))
+        assertEquals(listOf("history"), rules("// as before lint-allow version until 2026-12-01 by oryan: other rule"))
+        assertTrue(markerFix("// as before lint-allow history until 2026-11-03 by oryan: stale").contains("expired on 2026-11-03"))
+        assertTrue(markerFix("// as before lint-allow history until 2027-06-01 by oryan: too late").contains("more than 90 days"))
+        assertTrue(markerFix("// as before lint-allow history until 2026-12-01 by oryan:").contains("no reason"))
+        assertTrue(markerFix("// as before lint-allow histroy until 2026-12-01 by oryan: typo").contains("unknown rule `histroy`"))
+    }
+}
+
+internal object CommentLint {
+
+    class Violation(val path: String, val line: Int, val rule: String, val match: String, val lineText: String, val fix: String) {
+        override fun toString() = "$path:$line [$rule] \"$match\" in: $lineText\n    fix: $fix"
+    }
+
+    private const val MARKER_MAX_DAYS = 90L
+    private const val MARKER_FORM = "lint-allow <rule> until YYYY-MM-DD by <name>: <reason>"
+    private const val MOVE_TO_PR = "move the reason into the PR description"
+
+    private class Rule(val id: String, val pattern: Regex, advice: String) {
+        val fix = "$advice; for a false positive add `lint-allow $id until YYYY-MM-DD by <name>: <reason>` to the line, " +
+            "at most $MARKER_MAX_DAYS days out"
+    }
+
+    private val ordinalNouns = listOf("step", "phase", "stage", "item", "case", "rule", "row", "column", "line", "attempt", "round", "part", "pass", "example", "option")
+
+    private val historyPhrases = listOf(
+        """\bused to be\b""",
+        """\bno longer (?:needed|necessary|required|supported|used|works?|fails?|throws?|returns?|builds?|breaks?|applies|happens|exists?|runs?)\b""",
+        """\banymore\b""",
+        """\bbefore (?:this|that) (?:change|check|fix|pr|commit)\b""",
+        """\bbefore the (?:fix|pr)\b""",
+        """\b(?:before|after|until|since) #\d+""",
+        """\bas (?:it|they) did\b""",
+        """\b(?:as|like|than) before\b""",
+        """\bkeeps? (?:those|these|such|existing|old) (?:\w+ )?(?:building|working)\b""",
+        """\b(?:those|these|such|existing|old) schemas? (?:still|keeps?) (?:builds?|building|works?|working)\b""",
+        """\bkeeps? building (?:\w+ )?schemas?\b""",
+        """\bschemas? keeps? building\b""",
+        """\b(?:old|previous) behaviou?r\b""",
+    )
+
+    private val rules = listOf(
+        Rule(
+            "issue-number",
+            Regex(
+                """(?<![\w&/])(?<!\b(?:${ordinalNouns.joinToString("|")}) )#\d{1,5}\b|github\.com/\S+/(?:issues|pull)/\d+""",
+                RegexOption.IGNORE_CASE
+            ),
+            "$MOVE_TO_PR; an issue number belongs only in `// TODO <change> in X.0.0 (#N)`"
+        ),
+        Rule(
+            "history",
+            Regex(historyPhrases.joinToString("|"), RegexOption.IGNORE_CASE),
+            "say what the code does and why, not how it got here; $MOVE_TO_PR"
+        ),
+        Rule(
+            "version",
+            Regex("""@since\b|\bsince (?:v\d+(?:\.\d+)*|version \d+(?:\.\d+)*|\d+\.\d+\.\d+)\b""", RegexOption.IGNORE_CASE),
+            "drop the version; history goes in the release notes"
+        ),
+    )
+
+    private val marker = Regex("""lint-allow [\w-]+ until\b.*""")
+    private val markerParts = Regex("""lint-allow ([\w-]+) until (\S+) by [\w-]+: ?(.*)""")
+    private val todoIssue = Regex("""\bTODO\b[^#]*?\bin \d+\.0\.0 (\(#\d+\))""")
+
+    fun check(path: String, source: String, today: LocalDate): List<Violation> =
+        CommentLexer(source, kotlin = path.endsWith(".kt")).blocks().flatMap { check(path, it, today) }
+
+    private fun check(path: String, block: List<Pair<Int, String>>, today: LocalDate): List<Violation> {
+        val violations = mutableListOf<Violation>()
+        val allowed = mutableMapOf<Int, String>()
+        val lineStarts = mutableListOf<Int>()
+        val text = StringBuilder()
+        block.forEach { (line, lineText) ->
+            val found = marker.find(lineText)
+            if (found != null) {
+                val parts = markerParts.matchEntire(found.value)
+                val problem = markerProblem(parts, today)
+                if (problem == null) allowed[line] = parts!!.groupValues[1]
+                else violations += Violation(
+                    path, line, "lint-allow", found.value, lineText,
+                    "$problem; write `$MARKER_FORM` with a rule from ${rules.joinToString { it.id }} and a date at most " +
+                        "$MARKER_MAX_DAYS days out, or reword the comment and drop the marker"
+                )
+            }
+            if (text.isNotEmpty()) text.append(' ')
+            lineStarts += text.length
+            text.append(if (found == null) lineText else lineText.substring(0, found.range.first))
+        }
+        val checked = todoIssue.replace(text) {
+            val issue = it.groupValues[1]
+            it.value.dropLast(issue.length) + " ".repeat(issue.length)
+        }
+        rules.forEach { rule ->
+            rule.pattern.findAll(checked).forEach { match ->
+                val (line, lineText) = block[lineStarts.indexOfLast { it <= match.range.first }]
+                if (allowed[line] != rule.id) violations += Violation(path, line, rule.id, match.value, lineText, rule.fix)
+            }
+        }
+        return violations.sortedBy { it.line }
+    }
+
+    private fun markerProblem(parts: MatchResult?, today: LocalDate): String? {
+        if (parts == null) return "the marker does not have the form `$MARKER_FORM`"
+        val (rule, date, reason) = parts.destructured
+        val until = runCatching { LocalDate.parse(date) }.getOrNull()
+        return when {
+            rules.none { it.id == rule } -> "unknown rule `$rule`"
+            until == null -> "`$date` is not a YYYY-MM-DD date"
+            until.isBefore(today) -> "the marker expired on $until"
+            until.isAfter(today.plusDays(MARKER_MAX_DAYS)) -> "$until is more than $MARKER_MAX_DAYS days out"
+            reason.isBlank() -> "the marker has no reason after `by <name>:`"
+            else -> null
+        }
+    }
+}
+
+private class CommentLexer(private val source: String, private val kotlin: Boolean) {
+    private var pos = 0
+    private var line = 1
+    private var lastLineCommentLine = -1
+    private val blocks = mutableListOf<MutableList<Pair<Int, String>>>()
+
+    fun blocks(): List<List<Pair<Int, String>>> {
+        code(insideTemplate = false)
+        return blocks.map { block -> block.filter { it.second.isNotEmpty() } }.filter { it.isNotEmpty() }
+    }
+
+    private fun peek(text: String) = source.startsWith(text, pos)
+
+    private fun advance(count: Int = 1) {
+        repeat(count) {
+            if (pos < source.length && source[pos] == '\n') line++
+            pos++
+        }
+    }
+
+    private fun code(insideTemplate: Boolean) {
+        var depth = 0
+        while (pos < source.length) {
+            when {
+                peek("//") -> lineComment()
+                peek("/*") -> blockComment()
+                peek("\"\"\"") -> rawString()
+                peek("\"") -> string()
+                peek("'") -> quoted('\'')
+                peek("`") -> quoted('`')
+                insideTemplate && peek("{") -> { depth++; advance() }
+                insideTemplate && peek("}") -> { if (depth == 0) { advance(); return }; depth--; advance() }
+                else -> advance()
+            }
+        }
+    }
+
+    private fun lineComment() {
+        val end = source.indexOf('\n', pos).let { if (it < 0) source.length else it }
+        val entry = line to source.substring(pos, end).trimStart('/').trim()
+        if (lastLineCommentLine == line - 1) blocks.last() += entry else blocks += mutableListOf(entry)
+        lastLineCommentLine = line
+        pos = end
+    }
+
+    private fun blockComment() {
+        val startLine = line
+        val start = pos
+        advance(2)
+        var depth = 1
+        while (pos < source.length && depth > 0) {
+            when {
+                kotlin && peek("/*") -> { depth++; advance(2) }
+                peek("*/") -> { depth--; advance(2) }
+                else -> advance()
+            }
+        }
+        val lines = source.substring(start, pos).removePrefix("/**").removePrefix("/*").removeSuffix("*/").lines()
+        blocks += lines.mapIndexedTo(mutableListOf()) { index, text -> (startLine + index) to text.trim().removePrefix("*").trim() }
+        lastLineCommentLine = -1
+    }
+
+    private fun rawString() {
+        advance(3)
+        while (pos < source.length && !peek("\"\"\"")) {
+            when {
+                !kotlin && peek("\\") -> advance(2)
+                kotlin && peek("\${") -> { advance(2); code(insideTemplate = true) }
+                else -> advance()
+            }
+        }
+        advance(3)
+        while (kotlin && peek("\"")) advance()
+    }
+
+    private fun string() {
+        advance()
+        while (pos < source.length && !peek("\"") && !peek("\n")) {
+            when {
+                peek("\\") -> advance(2)
+                kotlin && peek("\${") -> { advance(2); code(insideTemplate = true) }
+                else -> advance()
+            }
+        }
+        advance()
+    }
+
+    private fun quoted(quote: Char) {
+        advance()
+        while (pos < source.length && source[pos] != quote && source[pos] != '\n') advance(if (peek("\\")) 2 else 1)
+        advance()
+    }
+}
diff --git a/src/test/kotlin/graphql/kickstart/tools/SchemaClassScannerDirectiveTest.kt b/src/test/kotlin/graphql/kickstart/tools/SchemaClassScannerDirectiveTest.kt
index d4be4579..34acc20b 100644
--- a/src/test/kotlin/graphql/kickstart/tools/SchemaClassScannerDirectiveTest.kt
+++ b/src/test/kotlin/graphql/kickstart/tools/SchemaClassScannerDirectiveTest.kt
@@ -293,7 +293,6 @@ class SchemaClassScannerDirectiveTest {
         assertEquals(error.message, message)
     }
 
-    // the enum and directive from issue #823
     private val linkDirective = """
         enum Purpose { SECURITY EXECUTION }