Add Grazie-backed grammar checker and dictionary support to Lyng IDEA plugin and variants for replacements with or without Grazie interfaces

lyng-idea/build.gradle.kts

@@ -49,7 +49,11 @@ intellij {
     updateSinceUntilBuild.set(false)
     // Include only available bundled plugins for this IDE build
     plugins.set(listOf(
-        "com.intellij.java"
+        "com.intellij.java",
+        // Provide Grazie API on compile classpath (bundled in 2024.3+, but add here for compilation)
+        "tanvd.grazi"
+        // Do not list com.intellij.spellchecker here: it is expected to be bundled with the IDE.
+        // Listing it causes Gradle to search for a separate plugin artifact and fail on IC 2024.3.
     ))
 }
 

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/annotators/LyngExternalAnnotator.kt

@@ -47,7 +47,10 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
 
     data class Span(val start: Int, val end: Int, val key: com.intellij.openapi.editor.colors.TextAttributesKey)
     data class Error(val start: Int, val end: Int, val message: String)
-    data class Result(val modStamp: Long, val spans: List<Span>, val error: Error? = null)
+    data class Result(val modStamp: Long, val spans: List<Span>, val error: Error? = null,
+                      val spellIdentifiers: List<IntRange> = emptyList(),
+                      val spellComments: List<IntRange> = emptyList(),
+                      val spellStrings: List<IntRange> = emptyList())
 
     override fun collectInformation(file: PsiFile): Input? {
         val doc: Document = file.viewProvider.document ?: return null
@@ -240,7 +243,29 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
             if (e is com.intellij.openapi.progress.ProcessCanceledException) throw e
         }
 
-        return Result(collectedInfo.modStamp, out, null)
+        // Build spell index payload: identifiers from symbols + references; comments/strings from simple highlighter
+        val idRanges = mutableSetOf<IntRange>()
+        try {
+            val binding = Binder.bind(text, mini)
+            for (sym in binding.symbols) {
+                val s = sym.declStart; val e = sym.declEnd
+                if (s in 0..e && e <= text.length && s < e) idRanges += (s until e)
+            }
+            for (ref in binding.references) {
+                val s = ref.start; val e = ref.end
+                if (s in 0..e && e <= text.length && s < e) idRanges += (s until e)
+            }
+        } catch (_: Throwable) {
+            // Best-effort; no identifiers if binder fails
+        }
+        val tokens = try { SimpleLyngHighlighter().highlight(text) } catch (_: Throwable) { emptyList() }
+        val commentRanges = tokens.filter { it.kind == HighlightKind.Comment }.map { it.range.start until it.range.endExclusive }
+        val stringRanges = tokens.filter { it.kind == HighlightKind.String }.map { it.range.start until it.range.endExclusive }
+
+        return Result(collectedInfo.modStamp, out, null,
+            spellIdentifiers = idRanges.toList(),
+            spellComments = commentRanges,
+            spellStrings = stringRanges)
     }
 
     override fun apply(file: PsiFile, annotationResult: Result?, holder: AnnotationHolder) {
@@ -252,6 +277,32 @@ class LyngExternalAnnotator : ExternalAnnotator<LyngExternalAnnotator.Input, Lyn
         val result = if (cached != null && currentStamp != null && cached.modStamp == currentStamp) cached else annotationResult
         file.putUserData(CACHE_KEY, result)
 
+        // Store spell index for spell/grammar engines to consume (suspend until ready)
+        val ids = result.spellIdentifiers.map { TextRange(it.first, it.last + 1) }
+        val coms = result.spellComments.map { TextRange(it.first, it.last + 1) }
+        val strs = result.spellStrings.map { TextRange(it.first, it.last + 1) }
+        net.sergeych.lyng.idea.spell.LyngSpellIndex.store(file,
+            net.sergeych.lyng.idea.spell.LyngSpellIndex.Data(
+                modStamp = result.modStamp,
+                identifiers = ids,
+                comments = coms,
+                strings = strs
+            )
+        )
+
+        // Optional diagnostic overlay: visualize the ranges we will feed to spellcheckers
+        val settings = net.sergeych.lyng.idea.settings.LyngFormatterSettings.getInstance(file.project)
+        if (settings.debugShowSpellFeed) {
+            fun paint(r: TextRange, label: String) {
+                holder.newAnnotation(HighlightSeverity.WEAK_WARNING, "spell-feed: $label")
+                    .range(r)
+                    .create()
+            }
+            ids.forEach { paint(it, "id") }
+            coms.forEach { paint(it, "comment") }
+            if (settings.spellCheckStringLiterals) strs.forEach { paint(it, "string") }
+        }
+
         for (s in result.spans) {
             holder.newSilentAnnotation(HighlightSeverity.INFORMATION)
                 .range(TextRange(s.start, s.end))

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/grazie/AddToLyngDictionaryFix.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.grazie
+
+import com.intellij.codeInsight.daemon.DaemonCodeAnalyzer
+import com.intellij.codeInsight.intention.IntentionAction
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiFile
+import net.sergeych.lyng.idea.settings.LyngFormatterSettings
+
+/**
+ * Lightweight quick-fix that adds a word to the per-project Lyng dictionary.
+ */
+class AddToLyngDictionaryFix(private val word: String) : IntentionAction {
+    override fun getText(): String = "Add '$word' to Lyng dictionary"
+    override fun getFamilyName(): String = "Lyng Spelling"
+    override fun isAvailable(project: Project, editor: Editor?, file: PsiFile?): Boolean = word.isNotBlank()
+    override fun startInWriteAction(): Boolean = true
+
+    override fun invoke(project: Project, editor: Editor?, file: PsiFile?) {
+        val settings = LyngFormatterSettings.getInstance(project)
+        val learned = settings.learnedWords
+        learned.add(word.lowercase())
+        settings.learnedWords = learned
+        // Restart daemon to refresh highlights
+        if (file != null) DaemonCodeAnalyzer.getInstance(project).restart(file)
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/grazie/EnglishDictionary.kt

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.grazie
+
+import com.intellij.openapi.diagnostic.Logger
+import java.io.BufferedReader
+import java.io.InputStreamReader
+import java.util.zip.GZIPInputStream
+
+/**
+ * Very simple English dictionary loader for offline suggestions on IC-243.
+ * It loads a word list from classpath resources. Supports plain text (one word per line)
+ * and gzipped text if the resource ends with .gz.
+ */
+object EnglishDictionary {
+    private val log = Logger.getInstance(EnglishDictionary::class.java)
+
+    @Volatile private var loaded = false
+    @Volatile private var words: Set<String> = emptySet()
+
+    /**
+     * Load dictionary from bundled resources (once).
+     * If multiple candidates exist, the first found is used.
+     */
+    private fun ensureLoaded() {
+        if (loaded) return
+        synchronized(this) {
+            if (loaded) return
+            val candidates = listOf(
+                // preferred large bundles first (add en-basic.txt.gz ~3–5MB here)
+                "/dictionaries/en-basic.txt.gz",
+                "/dictionaries/en-large.txt.gz",
+                // plain text fallbacks
+                "/dictionaries/en-basic.txt",
+                "/dictionaries/en-large.txt",
+            )
+            val merged = HashSet<String>(128_000)
+            for (res in candidates) {
+                try {
+                    val stream = javaClass.getResourceAsStream(res) ?: continue
+                    val reader = if (res.endsWith(".gz"))
+                        BufferedReader(InputStreamReader(GZIPInputStream(stream)))
+                    else
+                        BufferedReader(InputStreamReader(stream))
+                    var loadedCount = 0
+                    reader.useLines { seq -> seq.forEach { line ->
+                        val w = line.trim()
+                        if (w.isNotEmpty() && !w.startsWith("#")) { merged += w.lowercase(); loadedCount++ }
+                    } }
+                    log.info("EnglishDictionary: loaded $loadedCount words from $res (total=${merged.size})")
+                } catch (t: Throwable) {
+                    log.info("EnglishDictionary: failed to load $res: ${t.javaClass.simpleName}: ${t.message}")
+                }
+            }
+            if (merged.isEmpty()) {
+                // Fallback minimal set
+                merged += setOf("comment","comments","error","errors","found","file","not","word","words","count","value","name","class","function","string")
+                log.info("EnglishDictionary: using minimal built-in set (${merged.size})")
+            }
+            words = merged
+            loaded = true
+        }
+    }
+
+    fun allWords(): Set<String> {
+        ensureLoaded()
+        return words
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/grazie/LyngGrazieAnnotator.kt

@@ -0,0 +1,598 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/*
+ * Grazie-backed annotator for Lyng files.
+ *
+ * It consumes the MiniAst-driven LyngSpellIndex and, when Grazie is present,
+ * tries to run Grazie checks on the extracted TextContent. Results are painted
+ * as warnings in the editor. If the Grazie API changes, we use reflection and
+ * fail softly with INFO logs (no errors shown to users).
+ */
+package net.sergeych.lyng.idea.grazie
+
+import com.intellij.codeInsight.daemon.DaemonCodeAnalyzer
+import com.intellij.grazie.text.TextContent
+import com.intellij.grazie.text.TextContent.TextDomain
+import com.intellij.ide.plugins.PluginManagerCore
+import com.intellij.lang.annotation.AnnotationHolder
+import com.intellij.lang.annotation.ExternalAnnotator
+import com.intellij.lang.annotation.HighlightSeverity
+import com.intellij.openapi.application.ApplicationManager
+import com.intellij.openapi.diagnostic.Logger
+import com.intellij.openapi.editor.Document
+import com.intellij.openapi.editor.colors.TextAttributesKey
+import com.intellij.openapi.project.DumbAware
+import com.intellij.openapi.util.Key
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiFile
+import net.sergeych.lyng.idea.settings.LyngFormatterSettings
+import net.sergeych.lyng.idea.spell.LyngSpellIndex
+
+class LyngGrazieAnnotator : ExternalAnnotator<LyngGrazieAnnotator.Input, LyngGrazieAnnotator.Result>(), DumbAware {
+    private val log = Logger.getInstance(LyngGrazieAnnotator::class.java)
+
+    data class Input(val modStamp: Long)
+    data class Finding(val range: TextRange, val message: String)
+    data class Result(val modStamp: Long, val findings: List<Finding>)
+
+    override fun collectInformation(file: PsiFile): Input? {
+        val doc: Document = file.viewProvider.document ?: return null
+        // Only require Grazie presence; index readiness is checked in apply with a retry.
+        val grazie = isGrazieInstalled()
+        if (!grazie) {
+            log.info("LyngGrazieAnnotator.collectInformation: skip (grazie=false) file='${file.name}'")
+            return null
+        }
+        log.info("LyngGrazieAnnotator.collectInformation: file='${file.name}', modStamp=${doc.modificationStamp}")
+        return Input(doc.modificationStamp)
+    }
+
+    override fun doAnnotate(collectedInfo: Input?): Result? {
+        // All heavy lifting is done in apply where we have the file context
+        return collectedInfo?.let { Result(it.modStamp, emptyList()) }
+    }
+
+    override fun apply(file: PsiFile, annotationResult: Result?, holder: AnnotationHolder) {
+        if (annotationResult == null || !isGrazieInstalled()) return
+        val doc = file.viewProvider.document ?: return
+        val idx = LyngSpellIndex.getUpToDate(file) ?: run {
+            log.info("LyngGrazieAnnotator.apply: index not ready for '${file.name}', scheduling one-shot restart")
+            scheduleOneShotRestart(file, annotationResult.modStamp)
+            return
+        }
+
+        val settings = LyngFormatterSettings.getInstance(file.project)
+
+        // Build TextContent fragments for comments/strings/identifiers according to settings
+        val fragments = mutableListOf<Pair<TextContent, TextRange>>()
+        try {
+            fun addFragments(ranges: List<TextRange>, domain: TextDomain) {
+                for (r in ranges) {
+                    val local = rangeToTextContent(file, domain, r) ?: continue
+                    fragments += local to r
+                }
+            }
+            // Comments always via COMMENTS
+            addFragments(idx.comments, TextDomain.COMMENTS)
+            // Strings: LITERALS if requested, else COMMENTS if fallback enabled
+            if (settings.spellCheckStringLiterals) {
+                val domain = if (settings.grazieTreatLiteralsAsComments) TextDomain.COMMENTS else TextDomain.LITERALS
+                addFragments(idx.strings, domain)
+            }
+            // Identifiers via COMMENTS to force painting in 243 unless user disables fallback
+            val idsDomain = if (settings.grazieTreatIdentifiersAsComments) TextDomain.COMMENTS else TextDomain.DOCUMENTATION
+            addFragments(idx.identifiers, idsDomain)
+            log.info(
+                "LyngGrazieAnnotator.apply: file='${file.name}', idxCounts ids=${idx.identifiers.size}, comments=${idx.comments.size}, strings=${idx.strings.size}, builtFragments=${fragments.size}"
+            )
+        } catch (e: Throwable) {
+            log.info("LyngGrazieAnnotator: failed to build TextContent fragments: ${e.javaClass.simpleName}: ${e.message}")
+            return
+        }
+
+        if (fragments.isEmpty()) return
+
+        val findings = mutableListOf<Finding>()
+        var totalReturned = 0
+        var chosenEntry: String? = null
+        for ((content, hostRange) in fragments) {
+            try {
+                val (typos, entryNote) = runGrazieChecksWithTracing(file, content)
+                if (chosenEntry == null) chosenEntry = entryNote
+                if (typos != null) {
+                    totalReturned += typos.size
+                    for (t in typos) {
+                        val rel = extractRangeFromTypo(t) ?: continue
+                        // Map relative range inside fragment to host file range
+                        val abs = TextRange(hostRange.startOffset + rel.startOffset, hostRange.startOffset + rel.endOffset)
+                        findings += Finding(abs, extractMessageFromTypo(t) ?: "Spelling/Grammar")
+                    }
+                }
+            } catch (e: Throwable) {
+                log.info("LyngGrazieAnnotator: Grazie check failed: ${e.javaClass.simpleName}: ${e.message}")
+            }
+        }
+        log.info("LyngGrazieAnnotator.apply: used=${chosenEntry ?: "<none>"}, totalFindings=$totalReturned, painting=${findings.size}")
+
+        // Guarded fallback: if Grazie returned nothing but we clearly have fragments, try legacy spellchecker via reflection
+        if (findings.isEmpty() && fragments.isNotEmpty()) {
+            val added = fallbackWithLegacySpellcheckerIfAvailable(file, fragments, holder)
+            log.info("LyngGrazieAnnotator.apply: fallback painted=$added (0 means no legacy and heuristic may have painted separately)")
+            // Ensure at least one visible mark for diagnostics: paint a small WARNING at the first fragment range
+            try {
+                val first = fragments.first().second
+                val diagRange = TextRange(first.startOffset, (first.startOffset + 2).coerceAtMost(first.endOffset))
+                val ab = holder.newAnnotation(HighlightSeverity.INFORMATION, "[LyngSpell] active").range(diagRange)
+                applyTypoStyleIfRequested(file, ab)
+                ab.create()
+                log.info("LyngGrazieAnnotator.apply: painted diagnostic marker at ${diagRange.startOffset}..${diagRange.endOffset}")
+            } catch (_: Throwable) {
+                // ignore
+            }
+        }
+
+        for (f in findings) {
+            val ab = holder.newAnnotation(HighlightSeverity.INFORMATION, f.message).range(f.range)
+            applyTypoStyleIfRequested(file, ab)
+            ab.create()
+        }
+    }
+
+    private fun scheduleOneShotRestart(file: PsiFile, modStamp: Long) {
+        try {
+            val last = file.getUserData(RETRY_KEY)
+            if (last == modStamp) {
+                log.info("LyngGrazieAnnotator.restart: already retried for modStamp=$modStamp, skip")
+                return
+            }
+            file.putUserData(RETRY_KEY, modStamp)
+            ApplicationManager.getApplication().invokeLater({
+                try {
+                    DaemonCodeAnalyzer.getInstance(file.project).restart(file)
+                    log.info("LyngGrazieAnnotator.restart: daemon restarted for '${file.name}'")
+                } catch (e: Throwable) {
+                    log.info("LyngGrazieAnnotator.restart failed: ${e.javaClass.simpleName}: ${e.message}")
+                }
+            })
+        } catch (e: Throwable) {
+            log.info("LyngGrazieAnnotator.scheduleOneShotRestart failed: ${e.javaClass.simpleName}: ${e.message}")
+        }
+    }
+
+    private fun isGrazieInstalled(): Boolean {
+        return PluginManagerCore.isPluginInstalled(com.intellij.openapi.extensions.PluginId.getId("com.intellij.grazie")) ||
+                PluginManagerCore.isPluginInstalled(com.intellij.openapi.extensions.PluginId.getId("tanvd.grazi"))
+    }
+
+    private fun rangeToTextContent(file: PsiFile, domain: TextDomain, range: TextRange): TextContent? {
+        // Build TextContent via reflection: prefer psiFragment(domain, element)
+        return try {
+            // Try to find an element that fully covers the target range
+            var element = file.findElementAt(range.startOffset) ?: return null
+            val start = range.startOffset
+            val end = range.endOffset
+            while (element.parent != null && (element.textRange.startOffset > start || element.textRange.endOffset < end)) {
+                element = element.parent
+            }
+            if (element.textRange.startOffset > start || element.textRange.endOffset < end) return null
+            // In many cases, the element may not span the whole range; use file + range via suitable factory
+            val methods = TextContent::class.java.methods.filter { it.name == "psiFragment" }
+            val byElementDomain = methods.firstOrNull { it.parameterCount == 2 && it.parameterTypes[0].name.endsWith("PsiElement") }
+            if (byElementDomain != null) {
+                @Suppress("UNCHECKED_CAST")
+                return (byElementDomain.invoke(null, element, domain) as? TextContent)?.let { tc ->
+                    val relStart = start - element.textRange.startOffset
+                    val relEnd = end - element.textRange.startOffset
+                    if (relStart < 0 || relEnd > tc.length || relStart >= relEnd) return null
+                    tc.subText(TextRange(relStart, relEnd))
+                }
+            }
+            val byDomainElement = methods.firstOrNull { it.parameterCount == 2 && it.parameterTypes[0].name.endsWith("TextDomain") }
+            if (byDomainElement != null) {
+                @Suppress("UNCHECKED_CAST")
+                return (byDomainElement.invoke(null, domain, element) as? TextContent)?.let { tc ->
+                    val relStart = start - element.textRange.startOffset
+                    val relEnd = end - element.textRange.startOffset
+                    if (relStart < 0 || relEnd > tc.length || relStart >= relEnd) return null
+                    tc.subText(TextRange(relStart, relEnd))
+                }
+            }
+            null
+        } catch (e: Throwable) {
+            log.info("LyngGrazieAnnotator: rangeToTextContent failed: ${e.javaClass.simpleName}: ${e.message}")
+            null
+        }
+    }
+
+    private fun runGrazieChecksWithTracing(file: PsiFile, content: TextContent): Pair<Collection<Any>?, String?> {
+        // Try known entry points via reflection to avoid hard dependencies on Grazie internals
+        try {
+            // 1) Static GrammarChecker.check(TextContent)
+            val checkerCls = try { Class.forName("com.intellij.grazie.grammar.GrammarChecker") } catch (t: Throwable) {
+                log.info("LyngGrazieAnnotator: GrammarChecker class not found: ${t.javaClass.simpleName}: ${t.message}")
+                null
+            }
+            if (checkerCls != null) {
+                // Diagnostic: list available 'check' methods once
+                runCatching {
+                    val checks = checkerCls.methods.filter { it.name == "check" }
+                    val sig = checks.joinToString { m ->
+                        val params = m.parameterTypes.joinToString(prefix = "(", postfix = ")") { it.simpleName }
+                        "${m.name}$params static=${java.lang.reflect.Modifier.isStatic(m.modifiers)}"
+                    }
+                    log.info("LyngGrazieAnnotator: GrammarChecker.check candidates: ${if (sig.isEmpty()) "<none>" else sig}")
+                }
+                checkerCls.methods.firstOrNull { it.name == "check" && it.parameterCount == 1 && it.parameterTypes[0].name.endsWith("TextContent") }?.let { m ->
+                    @Suppress("UNCHECKED_CAST")
+                    val res = m.invoke(null, content) as? Collection<Any>
+                    return res to "GrammarChecker.check(TextContent) static"
+                }
+                // 2) GrammarChecker.getInstance().check(TextContent)
+                val getInstance = checkerCls.methods.firstOrNull { it.name == "getInstance" && it.parameterCount == 0 }
+                val inst = getInstance?.invoke(null)
+                if (inst != null) {
+                    val m = checkerCls.methods.firstOrNull { it.name == "check" && it.parameterCount == 1 && it.parameterTypes[0].name.endsWith("TextContent") }
+                    if (m != null) {
+                        @Suppress("UNCHECKED_CAST")
+                        val res = m.invoke(inst, content) as? Collection<Any>
+                        return res to "GrammarChecker.getInstance().check(TextContent)"
+                    }
+                }
+                // 3) GrammarChecker.getDefault().check(TextContent)
+                val getDefault = checkerCls.methods.firstOrNull { it.name == "getDefault" && it.parameterCount == 0 }
+                val def = getDefault?.invoke(null)
+                if (def != null) {
+                    val m = checkerCls.methods.firstOrNull { it.name == "check" && it.parameterCount == 1 && it.parameterTypes[0].name.endsWith("TextContent") }
+                    if (m != null) {
+                        @Suppress("UNCHECKED_CAST")
+                        val res = m.invoke(def, content) as? Collection<Any>
+                        return res to "GrammarChecker.getDefault().check(TextContent)"
+                    }
+                }
+                // 4) Service from project/application: GrammarChecker as a service
+                runCatching {
+                    val app = com.intellij.openapi.application.ApplicationManager.getApplication()
+                    val getService = app::class.java.methods.firstOrNull { it.name == "getService" && it.parameterCount == 1 }
+                    val svc = getService?.invoke(app, checkerCls)
+                    if (svc != null) {
+                        val m = checkerCls.methods.firstOrNull { it.name == "check" && it.parameterCount == 1 && it.parameterTypes[0].name.endsWith("TextContent") }
+                        if (m != null) {
+                            @Suppress("UNCHECKED_CAST")
+                            val res = m.invoke(svc, content) as? Collection<Any>
+                            if (res != null) return res to "Application.getService(GrammarChecker).check(TextContent)"
+                        }
+                    }
+                }
+                runCatching {
+                    val getService = file.project::class.java.methods.firstOrNull { it.name == "getService" && it.parameterCount == 1 }
+                    val svc = getService?.invoke(file.project, checkerCls)
+                    if (svc != null) {
+                        val m = checkerCls.methods.firstOrNull { it.name == "check" && it.parameterCount == 1 && it.parameterTypes[0].name.endsWith("TextContent") }
+                        if (m != null) {
+                            @Suppress("UNCHECKED_CAST")
+                            val res = m.invoke(svc, content) as? Collection<Any>
+                            if (res != null) return res to "Project.getService(GrammarChecker).check(TextContent)"
+                        }
+                    }
+                }
+            }
+            // 5) Fallback: search any public method named check that accepts TextContent in any Grazie class (static)
+            val candidateClasses = listOf(
+                "com.intellij.grazie.grammar.GrammarChecker",
+                "com.intellij.grazie.grammar.GrammarRunner",
+                "com.intellij.grazie.grammar.Grammar" // historical names
+            )
+            for (cn in candidateClasses) {
+                val cls = try { Class.forName(cn) } catch (_: Throwable) { continue }
+                val m = cls.methods.firstOrNull { it.name == "check" && it.parameterTypes.any { p -> p.name.endsWith("TextContent") } }
+                if (m != null) {
+                    val args = arrayOfNulls<Any>(m.parameterCount)
+                    // place content to the first TextContent parameter; others left null (common defaults)
+                    for (i in 0 until m.parameterCount) if (m.parameterTypes[i].name.endsWith("TextContent")) { args[i] = content; break }
+                    @Suppress("UNCHECKED_CAST")
+                    val res = m.invoke(null, *args) as? Collection<Any>
+                    if (res != null) return res to "$cn.${m.name}(TextContent)"
+                }
+            }
+            // 6) Kotlin top-level function: GrammarCheckerKt.check(TextContent)
+            runCatching {
+                val kt = Class.forName("com.intellij.grazie.grammar.GrammarCheckerKt")
+                val m = kt.methods.firstOrNull { it.name == "check" && it.parameterTypes.any { p -> p.name.endsWith("TextContent") } }
+                if (m != null) {
+                    val args = arrayOfNulls<Any>(m.parameterCount)
+                    for (i in 0 until m.parameterCount) if (m.parameterTypes[i].name.endsWith("TextContent")) { args[i] = content; break }
+                    @Suppress("UNCHECKED_CAST")
+                    val res = m.invoke(null, *args) as? Collection<Any>
+                    if (res != null) return res to "GrammarCheckerKt.check(TextContent)"
+                }
+            }
+        } catch (e: Throwable) {
+            log.info("LyngGrazieAnnotator: runGrazieChecks reflection failed: ${e.javaClass.simpleName}: ${e.message}")
+        }
+        return null to null
+    }
+
+    private fun extractRangeFromTypo(typo: Any): TextRange? {
+        // Try to get a relative range from returned Grazie issue/typo via common accessors
+        return try {
+            // Common getters
+            val m1 = typo.javaClass.methods.firstOrNull { it.name == "getRange" && it.parameterCount == 0 }
+            val r1 = if (m1 != null) m1.invoke(typo) else null
+            when (r1) {
+                is TextRange -> return r1
+                is IntRange -> return TextRange(r1.first, r1.last + 1)
+            }
+            val m2 = typo.javaClass.methods.firstOrNull { it.name == "getHighlightRange" && it.parameterCount == 0 }
+            val r2 = if (m2 != null) m2.invoke(typo) else null
+            when (r2) {
+                is TextRange -> return r2
+                is IntRange -> return TextRange(r2.first, r2.last + 1)
+            }
+            // Separate from/to ints
+            val fromM = typo.javaClass.methods.firstOrNull { it.name == "getFrom" && it.parameterCount == 0 && it.returnType == Int::class.javaPrimitiveType }
+            val toM = typo.javaClass.methods.firstOrNull { it.name == "getTo" && it.parameterCount == 0 && it.returnType == Int::class.javaPrimitiveType }
+            if (fromM != null && toM != null) {
+                val s = (fromM.invoke(typo) as? Int) ?: return null
+                val e = (toM.invoke(typo) as? Int) ?: return null
+                if (e > s) return TextRange(s, e)
+            }
+            null
+        } catch (_: Throwable) { null }
+    }
+
+    private fun extractMessageFromTypo(typo: Any): String? {
+        return try {
+            val m = typo.javaClass.methods.firstOrNull { it.name == "getMessage" && it.parameterCount == 0 }
+            (m?.invoke(typo) as? String)
+        } catch (_: Throwable) { null }
+    }
+
+    companion object {
+        private val RETRY_KEY: Key<Long> = Key.create("LYNG_GRAZIE_ANN_RETRY_STAMP")
+    }
+
+    // Fallback that uses legacy SpellCheckerManager (if present) via reflection to validate words in fragments.
+    // Returns number of warnings painted.
+    private fun fallbackWithLegacySpellcheckerIfAvailable(
+        file: PsiFile,
+        fragments: List<Pair<TextContent, TextRange>>,
+        holder: AnnotationHolder
+    ): Int {
+        return try {
+            val mgrCls = Class.forName("com.intellij.spellchecker.SpellCheckerManager")
+            val getInstance = mgrCls.methods.firstOrNull { it.name == "getInstance" && it.parameterCount == 1 }
+            val isCorrect = mgrCls.methods.firstOrNull { it.name == "isCorrect" && it.parameterCount == 1 && it.parameterTypes[0] == String::class.java }
+            if (getInstance == null || isCorrect == null) {
+                // No legacy spellchecker API available — fall back to naive painter
+                return naiveFallbackPaint(file, fragments, holder)
+            }
+            val mgr = getInstance.invoke(null, file.project)
+            if (mgr == null) {
+                // Legacy manager not present for this project — use naive fallback
+                return naiveFallbackPaint(file, fragments, holder)
+            }
+            var painted = 0
+            val docText = file.viewProvider.document?.text ?: return 0
+            val tokenRegex = Regex("[A-Za-z][A-Za-z0-9_']{2,}")
+            for ((content, hostRange) in fragments) {
+                val text = try { docText.substring(hostRange.startOffset, hostRange.endOffset) } catch (_: Throwable) { null } ?: continue
+                var seen = 0
+                var flagged = 0
+                for (m in tokenRegex.findAll(text)) {
+                    val token = m.value
+                    if ('%' in token) continue // skip printf fragments defensively
+                    // Split snake_case and camelCase within the token
+                    val parts = splitIdentifier(token)
+                    for (part in parts) {
+                        if (part.length <= 2) continue
+                        if (isAllowedWord(part)) continue
+                        // Quick allowlist for very common words to reduce noise if dictionaries differ
+                        val ok = try { isCorrect.invoke(mgr, part) as? Boolean } catch (_: Throwable) { null }
+                        if (ok == false) {
+                            // Map part back to original token occurrence within this hostRange
+                            val localStart = m.range.first + token.indexOf(part)
+                            val localEnd = localStart + part.length
+                            val abs = TextRange(hostRange.startOffset + localStart, hostRange.startOffset + localEnd)
+                            paintTypoAnnotation(file, holder, abs, part)
+                            painted++
+                            flagged++
+                        }
+                        seen++
+                    }
+                }
+                log.info("LyngGrazieAnnotator.fallback: fragment words=$seen, flagged=$flagged")
+            }
+            painted
+        } catch (_: Throwable) {
+            // If legacy manager is not available, fall back to a very naive heuristic (no external deps)
+            return naiveFallbackPaint(file, fragments, holder)
+        }
+    }
+
+    private fun naiveFallbackPaint(
+        file: PsiFile,
+        fragments: List<Pair<TextContent, TextRange>>,
+        holder: AnnotationHolder
+    ): Int {
+        var painted = 0
+        val docText = file.viewProvider.document?.text
+        val tokenRegex = Regex("[A-Za-z][A-Za-z0-9_']{2,}")
+        val baseWords = setOf(
+            // small, common vocabulary to catch near-miss typos in typical code/comments
+            "comment","comments","error","errors","found","file","not","word","words","count","value","name","class","function","string"
+        )
+        for ((content, hostRange) in fragments) {
+            val text: String? = docText?.let { dt ->
+                try { dt.substring(hostRange.startOffset, hostRange.endOffset) } catch (_: Throwable) { null }
+            }
+            if (text.isNullOrBlank()) continue
+            var seen = 0
+            var flagged = 0
+            for (m in tokenRegex.findAll(text)) {
+                val token = m.value
+                if ('%' in token) continue
+                val parts = splitIdentifier(token)
+                for (part in parts) {
+                    seen++
+                    val lower = part.lowercase()
+                    if (lower.length <= 2 || isAllowedWord(part)) continue
+                    // Heuristic: no vowels OR 3 repeated chars OR ends with unlikely double consonants
+                    val noVowel = lower.none { it in "aeiouy" }
+                    val triple = Regex("(.)\\1\\1").containsMatchIn(lower)
+                    val dblCons = Regex("[bcdfghjklmnpqrstvwxyz]{2}$").containsMatchIn(lower)
+                    var looksWrong = noVowel || triple || dblCons
+                    // Additional: low vowel ratio for length>=4
+                    if (!looksWrong && lower.length >= 4) {
+                        val vowels = lower.count { it in "aeiouy" }
+                        val ratio = if (lower.isNotEmpty()) vowels.toDouble() / lower.length else 1.0
+                        if (ratio < 0.25) looksWrong = true
+                    }
+                    // Additional: near-miss to a small base vocabulary (edit distance 1, or 2 for words >=6)
+                    if (!looksWrong) {
+                        for (bw in baseWords) {
+                            val d = editDistance(lower, bw)
+                            if (d == 1 || (d == 2 && lower.length >= 6)) { looksWrong = true; break }
+                        }
+                    }
+                    if (looksWrong) {
+                        val localStart = m.range.first + token.indexOf(part)
+                        val localEnd = localStart + part.length
+                        val abs = TextRange(hostRange.startOffset + localStart, hostRange.startOffset + localEnd)
+                        paintTypoAnnotation(file, holder, abs, part)
+                        painted++
+                        flagged++
+                    }
+                }
+            }
+            log.info("LyngGrazieAnnotator.fallback(naive): fragment words=$seen, flagged=$flagged")
+        }
+        return painted
+    }
+
+    private fun paintTypoAnnotation(file: PsiFile, holder: AnnotationHolder, range: TextRange, word: String) {
+        val settings = LyngFormatterSettings.getInstance(file.project)
+        val ab = holder.newAnnotation(HighlightSeverity.INFORMATION, "Possible typo")
+            .range(range)
+        applyTypoStyleIfRequested(file, ab)
+        if (settings.offerLyngTypoQuickFixes) {
+            // Offer lightweight fixes; for 243 provide Add-to-dictionary always
+            ab.withFix(net.sergeych.lyng.idea.grazie.AddToLyngDictionaryFix(word))
+            // Offer "Replace with…" candidates (top 7)
+            val cands = suggestReplacements(file, word).take(7)
+            for (c in cands) {
+                ab.withFix(net.sergeych.lyng.idea.grazie.ReplaceWordFix(range, word, c))
+            }
+        }
+        ab.create()
+    }
+
+    private fun applyTypoStyleIfRequested(file: PsiFile, ab: com.intellij.lang.annotation.AnnotationBuilder) {
+        val settings = LyngFormatterSettings.getInstance(file.project)
+        if (!settings.showTyposWithGreenUnderline) return
+        // Use the standard TYPO text attributes key used by the platform
+        val TYPO: TextAttributesKey = TextAttributesKey.createTextAttributesKey("TYPO")
+        try {
+            ab.textAttributes(TYPO)
+        } catch (_: Throwable) {
+            // some IDEs may not allow setting attributes on INFORMATION; ignore gracefully
+        }
+    }
+
+    private fun suggestReplacements(file: PsiFile, word: String): List<String> {
+        val lower = word.lowercase()
+        val fromProject = collectProjectWords(file)
+        val fromTech = TechDictionary.allWords()
+        val fromEnglish = EnglishDictionary.allWords()
+        // Merge with priority: project (p=0), tech (p=1), english (p=2)
+        val all = LinkedHashSet<String>()
+        all.addAll(fromProject)
+        all.addAll(fromTech)
+        all.addAll(fromEnglish)
+        data class Cand(val w: String, val d: Int, val p: Int)
+        val cands = ArrayList<Cand>(32)
+        for (w in all) {
+            if (w == lower) continue
+            if (kotlin.math.abs(w.length - lower.length) > 2) continue
+            val d = editDistance(lower, w)
+            val p = when {
+                w in fromProject -> 0
+                w in fromTech -> 1
+                else -> 2
+            }
+            cands += Cand(w, d, p)
+        }
+        cands.sortWith(compareBy<Cand> { it.d }.thenBy { it.p }.thenBy { it.w })
+        // Return a larger pool so callers can choose desired display count
+        return cands.take(16).map { it.w }
+    }
+
+    private fun collectProjectWords(file: PsiFile): Set<String> {
+        // Simple approach: use current file text; can be extended to project scanning later
+        val text = file.viewProvider.document?.text ?: return emptySet()
+        val out = LinkedHashSet<String>()
+        val tokenRegex = Regex("[A-Za-z][A-Za-z0-9_']{2,}")
+        for (m in tokenRegex.findAll(text)) {
+            val parts = splitIdentifier(m.value)
+            parts.forEach { out += it.lowercase() }
+        }
+        // Include learned words
+        val settings = LyngFormatterSettings.getInstance(file.project)
+        out.addAll(settings.learnedWords.map { it.lowercase() })
+        return out
+    }
+
+    private fun splitIdentifier(token: String): List<String> {
+        // Split on underscores and camelCase boundaries
+        val unders = token.split('_').filter { it.isNotBlank() }
+        val out = mutableListOf<String>()
+        val camelBoundary = Regex("(?<=[a-z])(?=[A-Z])")
+        for (u in unders) out += u.split(camelBoundary).filter { it.isNotBlank() }
+        return out
+    }
+
+    private fun isAllowedWord(w: String): Boolean {
+        val s = w.lowercase()
+        return s in setOf(
+            // common code words / language keywords to avoid noise
+            "val","var","fun","class","enum","type","import","package","return","if","else","when","while","for","try","catch","finally","true","false","null",
+            // very common English words
+            "the","and","or","not","with","from","into","this","that","file","found","count","name","value","object"
+        )
+    }
+
+    private fun editDistance(a: String, b: String): Int {
+        if (a == b) return 0
+        if (a.isEmpty()) return b.length
+        if (b.isEmpty()) return a.length
+        val dp = IntArray(b.length + 1) { it }
+        for (i in 1..a.length) {
+            var prev = dp[0]
+            dp[0] = i
+            for (j in 1..b.length) {
+                val temp = dp[j]
+                dp[j] = minOf(
+                    dp[j] + 1,                // deletion
+                    dp[j - 1] + 1,            // insertion
+                    prev + if (a[i - 1] == b[j - 1]) 0 else 1 // substitution
+                )
+                prev = temp
+            }
+        }
+        return dp[b.length]
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/grazie/LyngGrazieStrategy.kt

@@ -0,0 +1,139 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.grazie
+
+import com.intellij.grazie.grammar.strategy.GrammarCheckingStrategy
+import com.intellij.grazie.grammar.strategy.GrammarCheckingStrategy.TextDomain
+import com.intellij.ide.plugins.PluginManagerCore
+import com.intellij.openapi.diagnostic.Logger
+import com.intellij.openapi.extensions.PluginId
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiElement
+import net.sergeych.lyng.idea.highlight.LyngTokenTypes
+import net.sergeych.lyng.idea.settings.LyngFormatterSettings
+import net.sergeych.lyng.idea.spell.LyngSpellIndex
+
+/**
+ * Grazie/Natural Languages strategy for Lyng.
+ *
+ * - Comments: checked as natural language (TextDomain.COMMENTS)
+ * - String literals: optionally checked (setting), skipping printf-like specifiers via stealth ranges (TextDomain.LITERALS)
+ * - Identifiers (non-keywords): checked under TextDomain.CODE so "Process code" controls apply
+ * - Keywords: skipped
+ */
+class LyngGrazieStrategy : GrammarCheckingStrategy {
+
+    private val log = Logger.getInstance(LyngGrazieStrategy::class.java)
+    @Volatile private var loggedOnce = false
+    @Volatile private var loggedFirstMatch = false
+    private val seenTypes: MutableSet<String> = java.util.Collections.synchronizedSet(mutableSetOf())
+
+    private fun legacySpellcheckerInstalled(): Boolean =
+        PluginManagerCore.isPluginInstalled(PluginId.getId("com.intellij.spellchecker"))
+
+    // Regex for printf-style specifiers: %[flags][width][.precision][length]type
+    private val spec = Regex("%(?:[-+ #0]*(?:\\d+)?(?:\\.\\d+)?[a-zA-Z%])")
+
+    override fun isMyContextRoot(element: PsiElement): Boolean {
+        val type = element.node?.elementType
+        val settings = LyngFormatterSettings.getInstance(element.project)
+        val legacyPresent = legacySpellcheckerInstalled()
+        if (type != null && seenTypes.size < 10) {
+            val name = type.toString()
+            if (seenTypes.add(name)) {
+                log.info("LyngGrazieStrategy: saw PSI type=$name")
+            }
+        }
+        if (!loggedOnce) {
+            loggedOnce = true
+            log.info("LyngGrazieStrategy activated: legacyPresent=$legacyPresent, preferGrazieForCommentsAndLiterals=${settings.preferGrazieForCommentsAndLiterals}, spellCheckStringLiterals=${settings.spellCheckStringLiterals}, grazieChecksIdentifiers=${settings.grazieChecksIdentifiers}")
+        }
+
+        val file = element.containingFile ?: return false
+        val index = LyngSpellIndex.getUpToDate(file) ?: return false // Suspend until ready
+        // To ensure Grazie asks TextExtractor for all leafs, accept any Lyng element once index is ready.
+        // The extractor will decide per-range/domain what to actually provide.
+        if (!loggedFirstMatch) {
+            loggedFirstMatch = true
+            log.info("LyngGrazieStrategy: enabling Grazie on all Lyng elements (index ready)")
+        }
+        return true
+    }
+
+    override fun getContextRootTextDomain(root: PsiElement): TextDomain {
+        val type = root.node?.elementType
+        val settings = LyngFormatterSettings.getInstance(root.project)
+        val file = root.containingFile
+        val index = if (file != null) LyngSpellIndex.getUpToDate(file) else null
+        val r = root.textRange
+
+        fun overlaps(list: List<TextRange>): Boolean = r != null && list.any { it.intersects(r) }
+
+        return when (type) {
+            LyngTokenTypes.LINE_COMMENT, LyngTokenTypes.BLOCK_COMMENT -> TextDomain.COMMENTS
+            LyngTokenTypes.STRING -> if (settings.grazieTreatLiteralsAsComments) TextDomain.COMMENTS else TextDomain.LITERALS
+            LyngTokenTypes.IDENTIFIER -> {
+                // For Grazie-only reliability in 243, route identifiers via COMMENTS when configured
+                if (settings.grazieTreatIdentifiersAsComments && index != null && r != null && overlaps(index.identifiers))
+                    TextDomain.COMMENTS
+                else TextDomain.PLAIN_TEXT
+            }
+            else -> TextDomain.PLAIN_TEXT
+        }
+    }
+
+    // Note: do not override getLanguageSupport to keep compatibility with 243 API
+
+    override fun getStealthyRanges(root: PsiElement, text: CharSequence): java.util.LinkedHashSet<IntRange> {
+        val result = LinkedHashSet<IntRange>()
+        val type = root.node?.elementType
+        if (type == LyngTokenTypes.STRING) {
+            if (!shouldCheckLiterals(root)) {
+                // Hide the entire string when literals checking is disabled by settings
+                result += (0 until text.length)
+                return result
+            }
+            // Hide printf-like specifiers in strings
+            val (start, end) = stripQuotesBounds(text)
+            if (end > start) {
+                val content = text.subSequence(start, end)
+                for (m in spec.findAll(content)) {
+                    val ms = start + m.range.first
+                    val me = start + m.range.last
+                    result += (ms..me)
+                }
+                if (result.isNotEmpty()) {
+                    log.debug("LyngGrazieStrategy: hidden ${result.size} printf specifier ranges in string literal")
+                }
+            }
+        }
+        return result
+    }
+
+    override fun isEnabledByDefault(): Boolean = true
+
+    private fun shouldCheckLiterals(root: PsiElement): Boolean =
+        LyngFormatterSettings.getInstance(root.project).spellCheckStringLiterals
+
+    private fun stripQuotesBounds(text: CharSequence): Pair<Int, Int> {
+        if (text.length < 2) return 0 to text.length
+        val first = text.first()
+        val last = text.last()
+        return if ((first == '"' && last == '"') || (first == '\'' && last == '\''))
+            1 to (text.length - 1) else (0 to text.length)
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/grazie/LyngTextExtractor.kt

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.grazie
+
+import com.intellij.grazie.text.TextContent
+import com.intellij.grazie.text.TextContent.TextDomain
+import com.intellij.grazie.text.TextExtractor
+import com.intellij.openapi.diagnostic.Logger
+import com.intellij.psi.PsiElement
+import net.sergeych.lyng.idea.highlight.LyngTokenTypes
+import net.sergeych.lyng.idea.settings.LyngFormatterSettings
+import net.sergeych.lyng.idea.spell.LyngSpellIndex
+
+/**
+ * Provides Grazie with extractable text for Lyng PSI elements.
+ * We return text for identifiers, comments, and (optionally) string literals.
+ * printf-like specifiers are filtered by the Grammar strategy via stealth ranges.
+ */
+class LyngTextExtractor : TextExtractor() {
+    private val log = Logger.getInstance(LyngTextExtractor::class.java)
+    @Volatile private var loggedOnce = false
+    private val seen: MutableSet<String> = java.util.Collections.synchronizedSet(mutableSetOf())
+
+    override fun buildTextContent(element: PsiElement, allowedDomains: Set<TextDomain>): TextContent? {
+        val type = element.node?.elementType ?: return null
+        if (!loggedOnce) {
+            loggedOnce = true
+            log.info("LyngTextExtractor active; allowedDomains=${allowedDomains.joinToString()}")
+        }
+        val settings = LyngFormatterSettings.getInstance(element.project)
+        val file = element.containingFile
+        val index = if (file != null) LyngSpellIndex.getUpToDate(file) else null
+        val r = element.textRange
+
+        fun overlaps(list: List<com.intellij.openapi.util.TextRange>): Boolean = r != null && list.any { it.intersects(r) }
+
+        // Decide target domain by intersection with our MiniAst-driven index; prefer comments > strings > identifiers
+        var domain: TextDomain? = null
+        if (index != null && r != null) {
+            if (overlaps(index.comments)) domain = TextDomain.COMMENTS
+            else if (overlaps(index.strings) && settings.spellCheckStringLiterals) domain = TextDomain.LITERALS
+            else if (overlaps(index.identifiers)) domain = if (settings.grazieTreatIdentifiersAsComments) TextDomain.COMMENTS else TextDomain.DOCUMENTATION
+        } else {
+            // Fallback to token type if index is not ready (rare timing), mostly for comments
+            domain = when (type) {
+                LyngTokenTypes.LINE_COMMENT, LyngTokenTypes.BLOCK_COMMENT -> TextDomain.COMMENTS
+                else -> null
+            }
+        }
+        if (domain == null) return null
+
+        // If literals aren't requested but fallback is enabled, route strings as COMMENTS
+        if (domain == TextDomain.LITERALS && !allowedDomains.contains(TextDomain.LITERALS) && settings.grazieTreatLiteralsAsComments) {
+            domain = TextDomain.COMMENTS
+        }
+        if (!allowedDomains.contains(domain)) {
+            if (seen.add("deny-${domain.name}")) {
+                log.info("LyngTextExtractor: domain ${domain.name} not in allowedDomains; skipping")
+            }
+            return null
+        }
+        return try {
+            // Try common factory names across versions
+            val methods = TextContent::class.java.methods.filter { it.name == "psiFragment" }
+            val built: TextContent? = when {
+                // Try psiFragment(PsiElement, TextDomain)
+                methods.any { it.parameterCount == 2 && it.parameterTypes[0].name.contains("PsiElement") } -> {
+                    val m = methods.first { it.parameterCount == 2 && it.parameterTypes[0].name.contains("PsiElement") }
+                    @Suppress("UNCHECKED_CAST")
+                    (m.invoke(null, element, domain) as? TextContent)?.also {
+                        if (seen.add("ok-${domain.name}")) log.info("LyngTextExtractor: provided ${domain.name} for ${type} via psiFragment(element, domain)")
+                    }
+                }
+                // Try psiFragment(TextDomain, PsiElement)
+                methods.any { it.parameterCount == 2 && it.parameterTypes[0].name.endsWith("TextDomain") } -> {
+                    val m = methods.first { it.parameterCount == 2 && it.parameterTypes[0].name.endsWith("TextDomain") }
+                    @Suppress("UNCHECKED_CAST")
+                    (m.invoke(null, domain, element) as? TextContent)?.also {
+                        if (seen.add("ok-${domain.name}")) log.info("LyngTextExtractor: provided ${domain.name} for ${type} via psiFragment(domain, element)")
+                    }
+                }
+                else -> null
+            }
+            built
+        } catch (e: Throwable) {
+            log.info("LyngTextExtractor: failed to build TextContent: ${e.javaClass.simpleName}: ${e.message}")
+            null
+        }
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/grazie/ReplaceWordFix.kt

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.grazie
+
+import com.intellij.codeInsight.daemon.DaemonCodeAnalyzer
+import com.intellij.codeInsight.intention.IntentionAction
+import com.intellij.openapi.command.WriteCommandAction
+import com.intellij.openapi.editor.CaretModel
+import com.intellij.openapi.editor.Document
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiFile
+
+/**
+ * Lightweight quick-fix to replace a misspelled word (subrange) with a suggested alternative.
+ * Works without the legacy Spell Checker. The replacement is applied directly to the file text.
+ */
+class ReplaceWordFix(
+    private val range: TextRange,
+    private val original: String,
+    private val replacementRaw: String
+) : IntentionAction {
+
+    override fun getText(): String = "Replace '$original' with '$replacementRaw'"
+    override fun getFamilyName(): String = "Lyng Spelling"
+    override fun isAvailable(project: Project, editor: Editor?, file: PsiFile?): Boolean =
+        editor != null && file != null && range.startOffset in 0..range.endOffset
+
+    override fun startInWriteAction(): Boolean = true
+
+    override fun invoke(project: Project, editor: Editor?, file: PsiFile?) {
+        if (editor == null) return
+        val doc: Document = editor.document
+        val safeRange = range.constrainTo(doc)
+        val current = doc.getText(safeRange)
+        // Preserve basic case style based on the original token
+        val replacement = adaptCaseStyle(current, replacementRaw)
+        WriteCommandAction.runWriteCommandAction(project, "Replace word", null, Runnable {
+            doc.replaceString(safeRange.startOffset, safeRange.endOffset, replacement)
+        }, file)
+        // Move caret to end of replacement for convenience
+        try {
+            val caret: CaretModel = editor.caretModel
+            caret.moveToOffset(safeRange.startOffset + replacement.length)
+        } catch (_: Throwable) {}
+        // Restart daemon to refresh highlights
+        if (file != null) DaemonCodeAnalyzer.getInstance(project).restart(file)
+    }
+
+    private fun TextRange.constrainTo(doc: Document): TextRange {
+        val start = startOffset.coerceIn(0, doc.textLength)
+        val end = endOffset.coerceIn(start, doc.textLength)
+        return TextRange(start, end)
+    }
+
+    private fun adaptCaseStyle(sample: String, suggestion: String): String {
+        if (suggestion.isEmpty()) return suggestion
+        return when {
+            sample.all { it.isUpperCase() } -> suggestion.uppercase()
+            // PascalCase / Capitalized single word
+            sample.firstOrNull()?.isUpperCase() == true && sample.drop(1).any { it.isLowerCase() } ->
+                suggestion.replaceFirstChar { if (it.isLowerCase()) it.titlecase() else it.toString() }
+            // snake_case -> lower
+            sample.contains('_') -> suggestion.lowercase()
+            // camelCase -> lower first
+            sample.firstOrNull()?.isLowerCase() == true && sample.any { it.isUpperCase() } ->
+                suggestion.replaceFirstChar { it.lowercase() }
+            else -> suggestion
+        }
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/grazie/TechDictionary.kt

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.grazie
+
+import com.intellij.openapi.diagnostic.Logger
+import java.io.BufferedReader
+import java.io.InputStreamReader
+import java.util.zip.GZIPInputStream
+
+/**
+ * Lightweight technical/Lyng vocabulary dictionary.
+ * Loaded from classpath resources; supports .txt and .txt.gz. Merged with EnglishDictionary.
+ */
+object TechDictionary {
+    private val log = Logger.getInstance(TechDictionary::class.java)
+    @Volatile private var loaded = false
+    @Volatile private var words: Set<String> = emptySet()
+
+    private fun ensureLoaded() {
+        if (loaded) return
+        synchronized(this) {
+            if (loaded) return
+            val candidates = listOf(
+                "/dictionaries/tech-lyng.txt.gz",
+                "/dictionaries/tech-lyng.txt"
+            )
+            val merged = HashSet<String>(8_000)
+            for (res in candidates) {
+                try {
+                    val stream = javaClass.getResourceAsStream(res) ?: continue
+                    val reader = if (res.endsWith(".gz"))
+                        BufferedReader(InputStreamReader(GZIPInputStream(stream)))
+                    else
+                        BufferedReader(InputStreamReader(stream))
+                    var n = 0
+                    reader.useLines { seq -> seq.forEach { line ->
+                        val w = line.trim()
+                        if (w.isNotEmpty() && !w.startsWith("#")) { merged += w.lowercase(); n++ }
+                    } }
+                    log.info("TechDictionary: loaded $n words from $res (total=${merged.size})")
+                } catch (t: Throwable) {
+                    log.info("TechDictionary: failed to load $res: ${t.javaClass.simpleName}: ${t.message}")
+                }
+            }
+            if (merged.isEmpty()) {
+                merged += setOf(
+                    // minimal Lyng/tech seeding to avoid empty dictionary
+                    "lyng","miniast","binder","printf","specifier","specifiers","regex","token","tokens",
+                    "identifier","identifiers","keyword","keywords","comment","comments","string","strings",
+                    "literal","literals","formatting","formatter","grazie","typo","typos","dictionary","dictionaries"
+                )
+                log.info("TechDictionary: using minimal built-in set (${merged.size})")
+            }
+            words = merged
+            loaded = true
+        }
+    }
+
+    fun allWords(): Set<String> {
+        ensureLoaded()
+        return words
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/settings/LyngFormatterSettings.kt

@@ -32,6 +32,24 @@ class LyngFormatterSettings(private val project: Project) : PersistentStateCompo
         var reindentClosedBlockOnEnter: Boolean = true,
         var reindentPastedBlocks: Boolean = true,
         var normalizeBlockCommentIndent: Boolean = false,
+        var spellCheckStringLiterals: Boolean = true,
+        // When Grazie/Natural Languages is present, prefer it for comments and literals (avoid legacy duplicates)
+        var preferGrazieForCommentsAndLiterals: Boolean = true,
+        // When Grazie is available, also check identifiers via Grazie.
+        // Default OFF because Grazie typically doesn't flag code identifiers; legacy Spellchecker is better for code.
+        var grazieChecksIdentifiers: Boolean = false,
+        // Grazie-only fallback: treat identifiers as comments domain so Grazie applies spelling rules
+        var grazieTreatIdentifiersAsComments: Boolean = true,
+        // Grazie-only fallback: treat string literals as comments domain when LITERALS domain is not requested
+        var grazieTreatLiteralsAsComments: Boolean = true,
+        // Debug helper: show the exact ranges we feed to Grazie/legacy as weak warnings
+        var debugShowSpellFeed: Boolean = false,
+        // Visuals: render Lyng typos using the standard Typo green underline styling
+        var showTyposWithGreenUnderline: Boolean = true,
+        // Enable lightweight quick-fixes (Replace..., Add to dictionary) without legacy Spell Checker
+        var offerLyngTypoQuickFixes: Boolean = true,
+        // Per-project learned words (do not flag again)
+        var learnedWords: MutableSet<String> = mutableSetOf(),
     )
 
     private var myState: State = State()
@@ -62,6 +80,42 @@ class LyngFormatterSettings(private val project: Project) : PersistentStateCompo
         get() = myState.normalizeBlockCommentIndent
         set(value) { myState.normalizeBlockCommentIndent = value }
 
+    var spellCheckStringLiterals: Boolean
+        get() = myState.spellCheckStringLiterals
+        set(value) { myState.spellCheckStringLiterals = value }
+
+    var preferGrazieForCommentsAndLiterals: Boolean
+        get() = myState.preferGrazieForCommentsAndLiterals
+        set(value) { myState.preferGrazieForCommentsAndLiterals = value }
+
+    var grazieChecksIdentifiers: Boolean
+        get() = myState.grazieChecksIdentifiers
+        set(value) { myState.grazieChecksIdentifiers = value }
+
+    var grazieTreatIdentifiersAsComments: Boolean
+        get() = myState.grazieTreatIdentifiersAsComments
+        set(value) { myState.grazieTreatIdentifiersAsComments = value }
+
+    var grazieTreatLiteralsAsComments: Boolean
+        get() = myState.grazieTreatLiteralsAsComments
+        set(value) { myState.grazieTreatLiteralsAsComments = value }
+
+    var debugShowSpellFeed: Boolean
+        get() = myState.debugShowSpellFeed
+        set(value) { myState.debugShowSpellFeed = value }
+
+    var showTyposWithGreenUnderline: Boolean
+        get() = myState.showTyposWithGreenUnderline
+        set(value) { myState.showTyposWithGreenUnderline = value }
+
+    var offerLyngTypoQuickFixes: Boolean
+        get() = myState.offerLyngTypoQuickFixes
+        set(value) { myState.offerLyngTypoQuickFixes = value }
+
+    var learnedWords: MutableSet<String>
+        get() = myState.learnedWords
+        set(value) { myState.learnedWords = value }
+
     companion object {
         @JvmStatic
         fun getInstance(project: Project): LyngFormatterSettings = project.getService(LyngFormatterSettings::class.java)

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/settings/LyngFormatterSettingsConfigurable.kt

@@ -30,6 +30,12 @@ class LyngFormatterSettingsConfigurable(private val project: Project) : Configur
     private var reindentClosedBlockCb: JCheckBox? = null
     private var reindentPasteCb: JCheckBox? = null
     private var normalizeBlockCommentIndentCb: JCheckBox? = null
+    private var spellCheckLiteralsCb: JCheckBox? = null
+    private var preferGrazieCommentsLiteralsCb: JCheckBox? = null
+    private var grazieChecksIdentifiersCb: JCheckBox? = null
+    private var grazieIdsAsCommentsCb: JCheckBox? = null
+    private var grazieLiteralsAsCommentsCb: JCheckBox? = null
+    private var debugShowSpellFeedCb: JCheckBox? = null
 
     override fun getDisplayName(): String = "Lyng Formatter"
 
@@ -41,6 +47,12 @@ class LyngFormatterSettingsConfigurable(private val project: Project) : Configur
         reindentClosedBlockCb = JCheckBox("Reindent enclosed block on Enter after '}'")
         reindentPasteCb = JCheckBox("Reindent pasted blocks (align pasted code to current indent)")
         normalizeBlockCommentIndentCb = JCheckBox("Normalize block comment indentation [experimental]")
+        spellCheckLiteralsCb = JCheckBox("Spell check string literals (skip % specifiers like %s, %d, %-12s)")
+        preferGrazieCommentsLiteralsCb = JCheckBox("Prefer Natural Languages/Grazie for comments and string literals (avoid duplicates)")
+        grazieChecksIdentifiersCb = JCheckBox("Check identifiers via Natural Languages/Grazie when available")
+        grazieIdsAsCommentsCb = JCheckBox("Natural Languages/Grazie: treat identifiers as comments (forces spelling checks in 2024.3)")
+        grazieLiteralsAsCommentsCb = JCheckBox("Natural Languages/Grazie: treat string literals as comments when literals are not processed")
+        debugShowSpellFeedCb = JCheckBox("Debug: show spell-feed ranges (weak warnings)")
 
         // Tooltips / short help
         spacingCb?.toolTipText = "Applies minimal, safe spacing (e.g., around commas/operators, control-flow parens)."
@@ -48,11 +60,22 @@ class LyngFormatterSettingsConfigurable(private val project: Project) : Configur
         reindentClosedBlockCb?.toolTipText = "On Enter after a closing '}', reindent the just-closed {…} block using formatter rules."
         reindentPasteCb?.toolTipText = "When caret is in leading whitespace, reindent the pasted text and align it to the caret's indent."
         normalizeBlockCommentIndentCb?.toolTipText = "Experimental: normalize indentation inside /* … */ comments (code is not modified)."
+        preferGrazieCommentsLiteralsCb?.toolTipText = "When ON and Natural Languages/Grazie is installed, comments and string literals are checked by Grazie. Turn OFF to force legacy Spellchecker to check them."
+        grazieChecksIdentifiersCb?.toolTipText = "When ON and Natural Languages/Grazie is installed, identifiers (non-keywords) are checked by Grazie too."
+        grazieIdsAsCommentsCb?.toolTipText = "Grazie-only fallback: route identifiers as COMMENTS domain so Grazie applies spelling in 2024.3."
+        grazieLiteralsAsCommentsCb?.toolTipText = "Grazie-only fallback: when Grammar doesn't process literals, route strings as COMMENTS so they are checked."
+        debugShowSpellFeedCb?.toolTipText = "Show the exact ranges we feed to spellcheckers (ids/comments/strings) as weak warnings."
         p.add(spacingCb)
         p.add(wrappingCb)
         p.add(reindentClosedBlockCb)
         p.add(reindentPasteCb)
         p.add(normalizeBlockCommentIndentCb)
+        p.add(spellCheckLiteralsCb)
+        p.add(preferGrazieCommentsLiteralsCb)
+        p.add(grazieChecksIdentifiersCb)
+        p.add(grazieIdsAsCommentsCb)
+        p.add(grazieLiteralsAsCommentsCb)
+        p.add(debugShowSpellFeedCb)
         panel = p
         reset()
         return p
@@ -64,7 +87,13 @@ class LyngFormatterSettingsConfigurable(private val project: Project) : Configur
                 wrappingCb?.isSelected != s.enableWrapping ||
                 reindentClosedBlockCb?.isSelected != s.reindentClosedBlockOnEnter ||
                 reindentPasteCb?.isSelected != s.reindentPastedBlocks ||
-                normalizeBlockCommentIndentCb?.isSelected != s.normalizeBlockCommentIndent
+                normalizeBlockCommentIndentCb?.isSelected != s.normalizeBlockCommentIndent ||
+                spellCheckLiteralsCb?.isSelected != s.spellCheckStringLiterals ||
+                preferGrazieCommentsLiteralsCb?.isSelected != s.preferGrazieForCommentsAndLiterals ||
+                grazieChecksIdentifiersCb?.isSelected != s.grazieChecksIdentifiers ||
+                grazieIdsAsCommentsCb?.isSelected != s.grazieTreatIdentifiersAsComments ||
+                grazieLiteralsAsCommentsCb?.isSelected != s.grazieTreatLiteralsAsComments ||
+                debugShowSpellFeedCb?.isSelected != s.debugShowSpellFeed
     }
 
     override fun apply() {
@@ -74,6 +103,12 @@ class LyngFormatterSettingsConfigurable(private val project: Project) : Configur
         s.reindentClosedBlockOnEnter = reindentClosedBlockCb?.isSelected == true
         s.reindentPastedBlocks = reindentPasteCb?.isSelected == true
         s.normalizeBlockCommentIndent = normalizeBlockCommentIndentCb?.isSelected == true
+        s.spellCheckStringLiterals = spellCheckLiteralsCb?.isSelected == true
+        s.preferGrazieForCommentsAndLiterals = preferGrazieCommentsLiteralsCb?.isSelected == true
+        s.grazieChecksIdentifiers = grazieChecksIdentifiersCb?.isSelected == true
+        s.grazieTreatIdentifiersAsComments = grazieIdsAsCommentsCb?.isSelected == true
+        s.grazieTreatLiteralsAsComments = grazieLiteralsAsCommentsCb?.isSelected == true
+        s.debugShowSpellFeed = debugShowSpellFeedCb?.isSelected == true
     }
 
     override fun reset() {
@@ -83,5 +118,11 @@ class LyngFormatterSettingsConfigurable(private val project: Project) : Configur
         reindentClosedBlockCb?.isSelected = s.reindentClosedBlockOnEnter
         reindentPasteCb?.isSelected = s.reindentPastedBlocks
         normalizeBlockCommentIndentCb?.isSelected = s.normalizeBlockCommentIndent
+        spellCheckLiteralsCb?.isSelected = s.spellCheckStringLiterals
+        preferGrazieCommentsLiteralsCb?.isSelected = s.preferGrazieForCommentsAndLiterals
+        grazieChecksIdentifiersCb?.isSelected = s.grazieChecksIdentifiers
+        grazieIdsAsCommentsCb?.isSelected = s.grazieTreatIdentifiersAsComments
+        grazieLiteralsAsCommentsCb?.isSelected = s.grazieTreatLiteralsAsComments
+        debugShowSpellFeedCb?.isSelected = s.debugShowSpellFeed
     }
 }

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/spell/LyngSpellIndex.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.spell
+
+import com.intellij.openapi.diagnostic.Logger
+import com.intellij.openapi.util.Key
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiFile
+
+/**
+ * Per-file cached spellcheck index built from MiniAst-based highlighting and the lynglib highlighter.
+ * It exposes identifier, comment, and string literal ranges. Strategies should suspend until data is ready.
+ */
+object LyngSpellIndex {
+    private val LOG = Logger.getInstance(LyngSpellIndex::class.java)
+
+    data class Data(
+        val modStamp: Long,
+        val identifiers: List<TextRange>,
+        val comments: List<TextRange>,
+        val strings: List<TextRange>,
+    )
+
+    private val KEY: Key<Data> = Key.create("LYNG_SPELL_INDEX")
+
+    fun getUpToDate(file: PsiFile): Data? {
+        val doc = file.viewProvider.document ?: return null
+        val d = file.getUserData(KEY) ?: return null
+        return if (d.modStamp == doc.modificationStamp) d else null
+    }
+
+    fun store(file: PsiFile, data: Data) {
+        file.putUserData(KEY, data)
+        LOG.info("LyngSpellIndex built: ids=${data.identifiers.size}, comments=${data.comments.size}, strings=${data.strings.size}")
+    }
+}

lyng-idea/src/main/kotlin/net/sergeych/lyng/idea/spell/LyngSpellcheckingStrategy.kt

@@ -0,0 +1,155 @@
+/*
+ * Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package net.sergeych.lyng.idea.spell
+
+// Avoid Tokenizers helper to keep compatibility; implement our own tokenizers
+import com.intellij.ide.plugins.PluginManagerCore
+import com.intellij.openapi.diagnostic.Logger
+import com.intellij.openapi.extensions.PluginId
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiElement
+import com.intellij.spellchecker.inspections.PlainTextSplitter
+import com.intellij.spellchecker.tokenizer.SpellcheckingStrategy
+import com.intellij.spellchecker.tokenizer.TokenConsumer
+import com.intellij.spellchecker.tokenizer.Tokenizer
+import net.sergeych.lyng.idea.settings.LyngFormatterSettings
+
+/**
+ * Spellchecking strategy for Lyng:
+ * - Identifiers: checked as identifiers
+ * - Comments: checked as plain text
+ * - Keywords: skipped
+ * - String literals: optional (controlled by settings), and we exclude printf-style format specifiers like
+ *   %s, %d, %-12s, %0.2f, etc.
+ */
+class LyngSpellcheckingStrategy : SpellcheckingStrategy() {
+
+    private val log = Logger.getInstance(LyngSpellcheckingStrategy::class.java)
+    @Volatile private var loggedOnce = false
+
+    private fun grazieInstalled(): Boolean {
+        // Support both historical and bundled IDs
+        return PluginManagerCore.isPluginInstalled(PluginId.getId("com.intellij.grazie")) ||
+                PluginManagerCore.isPluginInstalled(PluginId.getId("tanvd.grazi"))
+    }
+
+    private fun grazieApiAvailable(): Boolean = try {
+        // If this class is absent (as in IC-243), third-party plugins can't run Grazie programmatically
+        Class.forName("com.intellij.grazie.grammar.GrammarChecker")
+        true
+    } catch (_: Throwable) { false }
+
+    override fun getTokenizer(element: PsiElement): Tokenizer<*> {
+        val hasGrazie = grazieInstalled()
+        val hasGrazieApi = grazieApiAvailable()
+        val settings = LyngFormatterSettings.getInstance(element.project)
+        if (!loggedOnce) {
+            loggedOnce = true
+            log.info("LyngSpellcheckingStrategy activated: hasGrazie=$hasGrazie, grazieApi=$hasGrazieApi, preferGrazieForCommentsAndLiterals=${settings.preferGrazieForCommentsAndLiterals}, spellCheckStringLiterals=${settings.spellCheckStringLiterals}, grazieChecksIdentifiers=${settings.grazieChecksIdentifiers}")
+        }
+
+        val file = element.containingFile ?: return EMPTY_TOKENIZER
+        val index = LyngSpellIndex.getUpToDate(file) ?: run {
+            // Suspend legacy spellcheck until MiniAst-based index is ready
+            return EMPTY_TOKENIZER
+        }
+        val elRange = element.textRange ?: return EMPTY_TOKENIZER
+
+        fun overlaps(list: List<TextRange>) = list.any { it.intersects(elRange) }
+
+        // Decide responsibility per settings
+        // If Grazie is present but its public API is not available (IC-243), do NOT delegate to it.
+        val preferGrazie = hasGrazie && hasGrazieApi && settings.preferGrazieForCommentsAndLiterals
+        val grazieIds = hasGrazie && hasGrazieApi && settings.grazieChecksIdentifiers
+
+        // Identifiers: only if range is within identifiers index and not delegated to Grazie
+        if (overlaps(index.identifiers) && !grazieIds) return IDENTIFIER_TOKENIZER
+
+        // Comments: only if not delegated to Grazie and overlapping indexed comments
+        if (!preferGrazie && overlaps(index.comments)) return COMMENT_TEXT_TOKENIZER
+
+        // Strings: only if not delegated to Grazie, literals checking enabled, and overlapping indexed strings
+        if (!preferGrazie && settings.spellCheckStringLiterals && overlaps(index.strings)) return STRING_WITH_PRINTF_EXCLUDES
+
+        return EMPTY_TOKENIZER
+    }
+
+    private object EMPTY_TOKENIZER : Tokenizer<PsiElement>() {
+        override fun tokenize(element: PsiElement, consumer: TokenConsumer) {}
+    }
+
+    private object IDENTIFIER_TOKENIZER : Tokenizer<PsiElement>() {
+        private val splitter = PlainTextSplitter.getInstance()
+        override fun tokenize(element: PsiElement, consumer: TokenConsumer) {
+            val text = element.text
+            if (text.isNullOrEmpty()) return
+            consumer.consumeToken(element, text, false, 0, TextRange(0, text.length), splitter)
+        }
+    }
+
+    private object COMMENT_TEXT_TOKENIZER : Tokenizer<PsiElement>() {
+        private val splitter = PlainTextSplitter.getInstance()
+        override fun tokenize(element: PsiElement, consumer: TokenConsumer) {
+            val text = element.text
+            if (text.isNullOrEmpty()) return
+            consumer.consumeToken(element, text, false, 0, TextRange(0, text.length), splitter)
+        }
+    }
+
+    private object STRING_WITH_PRINTF_EXCLUDES : Tokenizer<PsiElement>() {
+        private val splitter = PlainTextSplitter.getInstance()
+
+        // Regex for printf-style specifiers: %[flags][width][.precision][length]type
+        // This is intentionally permissive to skip common cases like %s, %d, %-12s, %08x, %.2f, %%
+        private val SPEC = Regex("%(?:[-+ #0]*(?:\\d+)?(?:\\.\\d+)?[a-zA-Z%])")
+
+        override fun tokenize(element: PsiElement, consumer: TokenConsumer) {
+            // Check project settings whether literals should be spell-checked
+            val settings = LyngFormatterSettings.getInstance(element.project)
+            if (!settings.spellCheckStringLiterals) return
+
+            val text = element.text
+            if (text.isEmpty()) return
+
+            // Try to strip surrounding quotes (simple lexer token for Lyng strings)
+            var startOffsetInElement = 0
+            var endOffsetInElement = text.length
+            if (text.length >= 2 && (text.first() == '"' && text.last() == '"' || text.first() == '\'' && text.last() == '\'')) {
+                startOffsetInElement = 1
+                endOffsetInElement = text.length - 1
+            }
+            if (endOffsetInElement <= startOffsetInElement) return
+
+            val content = text.substring(startOffsetInElement, endOffsetInElement)
+
+            var last = 0
+            for (m in SPEC.findAll(content)) {
+                val ms = m.range.first
+                val me = m.range.last + 1
+                if (ms > last) {
+                    val range = TextRange(startOffsetInElement + last, startOffsetInElement + ms)
+                    consumer.consumeToken(element, text, false, 0, range, splitter)
+                }
+                last = me
+            }
+            if (last < content.length) {
+                val range = TextRange(startOffsetInElement + last, startOffsetInElement + content.length)
+                consumer.consumeToken(element, text, false, 0, range, splitter)
+            }
+        }
+    }
+}

lyng-idea/src/main/resources/META-INF/grazie-bundled.xml

@@ -0,0 +1,29 @@
+<!--
+  ~ Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  ~
+  -->
+
+<!--
+  Grazie (bundled Natural Languages) optional descriptor for Lyng. Loaded when plugin ID com.intellij.grazie is present.
+-->
+<idea-plugin>
+    <extensions defaultExtensionNs="com.intellij">
+        <grazie.grammar.strategy language="Lyng"
+                                  implementationClass="net.sergeych.lyng.idea.grazie.LyngGrazieStrategy"/>
+        <!-- Provide text extraction for Lyng PSI so Grazie (bundled Natural Languages) can check content -->
+        <grazie.textExtractor language="Lyng"
+                              implementationClass="net.sergeych.lyng.idea.grazie.LyngTextExtractor"/>
+    </extensions>
+</idea-plugin>

lyng-idea/src/main/resources/META-INF/grazie-lite.xml

@@ -0,0 +1,30 @@
+<!--
+  ~ Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  ~
+  -->
+
+<!--
+  Grazie Lite/Pro optional descriptor for Lyng. Loaded when plugin ID tanvd.grazi is present.
+  It delegates to the same strategy class as the bundled Natural Languages.
+-->
+<idea-plugin>
+    <extensions defaultExtensionNs="com.intellij">
+        <grazie.grammar.strategy language="Lyng"
+                                  implementationClass="net.sergeych.lyng.idea.grazie.LyngGrazieStrategy"/>
+        <!-- Provide text extraction for Lyng PSI so Grazie can actually check content -->
+        <grazie.textExtractor language="Lyng"
+                              implementationClass="net.sergeych.lyng.idea.grazie.LyngTextExtractor"/>
+    </extensions>
+</idea-plugin>

lyng-idea/src/main/resources/META-INF/grazie.xml

@@ -0,0 +1,28 @@
+<!--
+  ~ Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  ~
+  -->
+
+<!--
+  Grazie (Lite/Pro/bundled) grammar checker extensions for Lyng. Loaded only when
+  the Grazie plugin is present. plugin.xml declares optional dependency with this config file.
+-->
+<idea-plugin>
+    <extensions defaultExtensionNs="com.intellij">
+        <!-- Register Lyng strategy for Grazie (Natural Languages). -->
+        <grazie.grammar.strategy language="Lyng"
+                                  implementationClass="net.sergeych.lyng.idea.grazie.LyngGrazieStrategy"/>
+    </extensions>
+</idea-plugin>

lyng-idea/src/main/resources/META-INF/plugin.xml

@@ -33,6 +33,12 @@
     <depends>com.intellij.modules.platform</depends>
     <!-- Needed for editor language features (syntax highlighting, etc.) -->
     <depends>com.intellij.modules.lang</depends>
+    <!-- Spellchecker support (optional). If present, load spellchecker.xml which registers our strategy. -->
+    <depends optional="true" config-file="spellchecker.xml">com.intellij.spellchecker</depends>
+    <!-- Grazie (Lite/Pro) grammar checker support (optional). If present, load grazie-lite.xml -->
+    <depends optional="true" config-file="grazie-lite.xml">tanvd.grazi</depends>
+    <!-- Some IDE builds may expose Grazie/Natural Languages under another ID; load grazie-bundled.xml -->
+    <depends optional="true" config-file="grazie-bundled.xml">com.intellij.grazie</depends>
 
     <extensions defaultExtensionNs="com.intellij">
         <!-- Language and file type -->
@@ -50,6 +56,9 @@
         <!-- External annotator for semantic highlighting -->
         <externalAnnotator language="Lyng" implementationClass="net.sergeych.lyng.idea.annotators.LyngExternalAnnotator"/>
 
+        <!-- Grazie-backed spell/grammar annotator (runs only when Grazie is installed) -->
+        <externalAnnotator language="Lyng" implementationClass="net.sergeych.lyng.idea.grazie.LyngGrazieAnnotator"/>
+
         <!-- Quick documentation provider bound to Lyng language -->
         <lang.documentationProvider language="Lyng" implementationClass="net.sergeych.lyng.idea.docs.LyngDocumentationProvider"/>
 
@@ -80,6 +89,7 @@
 
         <!-- If targeting SDKs with stable RawText API, the EP below can be enabled instead: -->
         <!-- <copyPastePreProcessor implementation="net.sergeych.lyng.idea.editor.LyngCopyPastePreProcessor"/> -->
+
     </extensions>
 
     <actions/>

lyng-idea/src/main/resources/META-INF/spellchecker.xml

@@ -0,0 +1,29 @@
+<!--
+  ~ Copyright 2025 Sergey S. Chernov real.sergeych@gmail.com
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  ~
+  -->
+
+<!--
+  Spellchecker extensions for Lyng are registered here and loaded only when
+  the com.intellij.spellchecker plugin is available. The dependency is marked
+  optional in plugin.xml with config-file="spellchecker.xml".
+-->
+<idea-plugin>
+    <extensions defaultExtensionNs="com.intellij">
+        <!-- Spellchecker strategy: identifiers + comments; literals configurable, skipping printf-like specs -->
+        <spellchecker.support language="Lyng"
+                              implementationClass="net.sergeych.lyng.idea.spell.LyngSpellcheckingStrategy"/>
+    </extensions>
+</idea-plugin>

lyng-idea/src/main/resources/dictionaries/en-basic.txt

@@ -0,0 +1,466 @@
+the
+be
+to
+of
+and
+a
+in
+that
+have
+I
+it
+for
+not
+on
+with
+he
+as
+you
+do
+at
+this
+but
+his
+by
+from
+they
+we
+say
+her
+she
+or
+an
+will
+my
+one
+all
+would
+there
+their
+what
+so
+up
+out
+if
+about
+who
+get
+which
+go
+me
+when
+make
+can
+like
+time
+no
+just
+him
+know
+take
+people
+into
+year
+your
+good
+some
+could
+them
+see
+other
+than
+then
+now
+look
+only
+come
+its
+over
+think
+also
+back
+after
+use
+two
+how
+our
+work
+first
+well
+way
+even
+new
+want
+because
+any
+these
+give
+day
+most
+us
+is
+are
+was
+were
+been
+being
+does
+did
+done
+has
+had
+having
+may
+might
+must
+shall
+should
+ought
+need
+used
+here
+therefore
+where
+why
+while
+until
+since
+before
+afterward
+between
+among
+without
+within
+through
+across
+against
+toward
+upon
+above
+below
+under
+around
+near
+far
+early
+late
+often
+always
+never
+seldom
+sometimes
+usually
+really
+very
+quite
+rather
+almost
+already
+again
+still
+yet
+soon
+today
+tomorrow
+yesterday
+number
+string
+boolean
+true
+false
+null
+none
+file
+files
+path
+paths
+line
+lines
+word
+words
+count
+value
+values
+name
+names
+title
+text
+message
+error
+errors
+warning
+warnings
+info
+information
+debug
+trace
+format
+printf
+specifier
+specifiers
+pattern
+patterns
+match
+matches
+regex
+version
+versions
+module
+modules
+package
+packages
+import
+imports
+export
+exports
+class
+classes
+object
+objects
+function
+functions
+method
+methods
+parameter
+parameters
+argument
+arguments
+variable
+variables
+constant
+constants
+type
+types
+generic
+generics
+map
+maps
+list
+lists
+array
+arrays
+set
+sets
+queue
+stack
+graph
+tree
+node
+nodes
+edge
+edges
+pair
+pairs
+key
+keys
+value
+values
+index
+indices
+length
+size
+empty
+contains
+equals
+compare
+greater
+less
+minimum
+maximum
+average
+sum
+total
+random
+round
+floor
+ceil
+sin
+cos
+tan
+sqrt
+abs
+min
+max
+read
+write
+open
+close
+append
+create
+delete
+remove
+update
+save
+load
+start
+stop
+run
+execute
+return
+break
+continue
+try
+catch
+finally
+throw
+throws
+if
+else
+when
+while
+for
+loop
+range
+case
+switch
+default
+optional
+required
+enable
+disable
+enabled
+disabled
+visible
+hidden
+public
+private
+protected
+internal
+external
+inline
+override
+abstract
+sealed
+open
+final
+static
+const
+lazy
+late
+init
+initialize
+configuration
+settings
+option
+options
+preference
+preferences
+project
+projects
+module
+modules
+build
+builds
+compile
+compiles
+compiler
+test
+tests
+testing
+assert
+assertion
+result
+results
+success
+failure
+status
+state
+context
+scope
+scopes
+token
+tokens
+identifier
+identifiers
+keyword
+keywords
+comment
+comments
+string
+strings
+literal
+literals
+formatting
+formatter
+spell
+spelling
+dictionary
+dictionaries
+language
+languages
+natural
+grazie
+typo
+typos
+suggest
+suggestion
+suggestions
+replace
+replacement
+replacements
+learn
+learned
+learns
+filter
+filters
+exclude
+excludes
+include
+includes
+bundle
+bundled
+resource
+resources
+gzipped
+plain
+text
+editor
+editors
+inspection
+inspections
+highlight
+highlighting
+underline
+underlines
+style
+styles
+range
+ranges
+offset
+offsets
+position
+positions
+apply
+applies
+provides
+present
+absent
+available
+unavailable
+version
+build
+platform
+ide
+intellij
+plugin
+plugins
+sandbox
+gradle
+kotlin
+java
+linux
+macos
+windows
+unix
+system
+systems
+support
+supports
+compatible
+compatibility
+fallback
+native
+automatic
+autoswitch
+switch
+switches

lyng-idea/src/main/resources/dictionaries/tech-lyng.txt

@@ -0,0 +1,282 @@
+# Lyng/tech vocabulary – one word per line, lowercase
+lyng
+miniast
+binder
+printf
+specifier
+specifiers
+regex
+regexp
+token
+tokens
+lexer
+parser
+syntax
+semantic
+highlight
+highlighting
+underline
+typo
+typos
+dictionary
+dictionaries
+grazie
+natural
+languages
+inspection
+inspections
+annotation
+annotator
+annotations
+quickfix
+quickfixes
+intention
+intentions
+replacement
+replacements
+identifier
+identifiers
+keyword
+keywords
+comment
+comments
+string
+strings
+literal
+literals
+formatting
+formatter
+splitter
+camelcase
+snakecase
+pascalcase
+uppercase
+lowercase
+titlecase
+case
+cases
+project
+module
+modules
+resource
+resources
+bundle
+bundled
+gzipped
+plaintext
+text
+range
+ranges
+offset
+offsets
+position
+positions
+apply
+applies
+runtime
+compile
+build
+artifact
+artifacts
+plugin
+plugins
+intellij
+idea
+sandbox
+gradle
+kotlin
+java
+jvm
+coroutines
+suspend
+scope
+scopes
+context
+contexts
+tokenizer
+tokenizers
+spell
+spelling
+spellcheck
+spellchecker
+fallback
+native
+autoswitch
+switch
+switching
+enable
+disable
+enabled
+disabled
+setting
+settings
+preference
+preferences
+editor
+filetype
+filetypes
+language
+languages
+psi
+psielement
+psifile
+textcontent
+textdomain
+stealth
+stealthy
+printfspec
+format
+formats
+pattern
+patterns
+match
+matches
+group
+groups
+node
+nodes
+tree
+graph
+edge
+edges
+pair
+pairs
+map
+maps
+list
+lists
+array
+arrays
+set
+sets
+queue
+stack
+index
+indices
+length
+size
+empty
+contains
+equals
+compare
+greater
+less
+minimum
+maximum
+average
+sum
+total
+random
+round
+floor
+ceil
+sin
+cos
+tan
+sqrt
+abs
+min
+max
+read
+write
+open
+close
+append
+create
+delete
+remove
+update
+save
+load
+start
+stop
+run
+execute
+return
+break
+continue
+try
+catch
+finally
+throw
+throws
+if
+else
+when
+while
+for
+loop
+rangeop
+caseop
+switchop
+default
+optional
+required
+public
+private
+protected
+internal
+external
+inline
+override
+abstract
+sealed
+open
+final
+static
+const
+lazy
+late
+init
+initialize
+configuration
+option
+options
+projectwide
+workspace
+crossplatform
+multiplatform
+commonmain
+jsmain
+native
+platform
+api
+implementation
+dependency
+dependencies
+classpath
+source
+sources
+document
+documents
+logging
+logger
+info
+debug
+trace
+warning
+error
+severity
+severitylevel
+intentionaction
+daemon
+daemoncodeanalyzer
+restart
+textattributes
+textattributeskey
+typostyle
+learned
+learn
+tech
+vocabulary
+domain
+term
+terms
+us
+uk
+american
+british
+colour
+color
+organisation
+organization