diff --git a/Partner-Core/pom.xml b/Partner-Core/pom.xml
index d6eafe5b..4e875887 100644
--- a/Partner-Core/pom.xml
+++ b/Partner-Core/pom.xml
@@ -65,6 +65,11 @@
             <artifactId>cron-utils</artifactId>
             <version>9.2.1</version>
         </dependency>
+        <dependency>
+            <groupId>com.huaban</groupId>
+            <artifactId>jieba-analysis</artifactId>
+            <version>1.0.2</version>
+        </dependency>
     </dependencies>
 
     <properties>
diff --git a/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/ImpressionTokenizer.kt b/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/ImpressionTokenizer.kt
new file mode 100644
index 00000000..984c961d
--- /dev/null
+++ b/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/ImpressionTokenizer.kt
@@ -0,0 +1,5 @@
+package work.slhaf.partner.core.cognition.impression.search
+
+interface ImpressionTokenizer {
+    fun tokenize(text: String): Set<String>
+}
\ No newline at end of file
diff --git a/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/JiebaImpressionTokenizer.kt b/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/JiebaImpressionTokenizer.kt
new file mode 100644
index 00000000..4b5d7f86
--- /dev/null
+++ b/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/JiebaImpressionTokenizer.kt
@@ -0,0 +1,37 @@
+package work.slhaf.partner.core.cognition.impression.search
+
+import com.huaban.analysis.jieba.JiebaSegmenter
+
+class JiebaImpressionTokenizer(
+    private val segmenter: JiebaSegmenter = JiebaSegmenter(),
+    private val mode: JiebaSegmenter.SegMode = JiebaSegmenter.SegMode.SEARCH,
+) : ImpressionTokenizer {
+
+    override fun tokenize(text: String): Set<String> {
+        val normalized = normalize(text)
+        if (normalized.isBlank()) {
+            return emptySet()
+        }
+
+        val jiebaTerms = segmenter.process(normalized, mode)
+            .asSequence()
+            .map { it.word }
+            .map(::normalize)
+            .filter { it.isNotBlank() }
+
+        return (jiebaTerms + alphaNumericTerms(normalized)).toSet()
+    }
+
+    private fun alphaNumericTerms(text: String): Sequence<String> =
+        ALPHA_NUMERIC_REGEX.findAll(text).map { it.value }
+
+    private fun normalize(text: String): String =
+        text.lowercase()
+            .replace(WHITESPACE_REGEX, " ")
+            .trim()
+
+    companion object {
+        private val WHITESPACE_REGEX = Regex("\\s+")
+        private val ALPHA_NUMERIC_REGEX = Regex("[a-z0-9]+(?:[-_./][a-z0-9]+)*")
+    }
+}
diff --git a/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/SimpleTextSearch.kt b/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/SimpleTextSearch.kt
new file mode 100644
index 00000000..e6174af2
--- /dev/null
+++ b/Partner-Core/src/main/java/work/slhaf/partner/core/cognition/impression/search/SimpleTextSearch.kt
@@ -0,0 +1,136 @@
+package work.slhaf.partner.core.cognition.impression.search
+
+class SimpleTextSearch(
+    private val tokenizer: ImpressionTokenizer = JiebaImpressionTokenizer(),
+) : ImpressionTextSearch {
+
+    private val documents = linkedMapOf<String, IndexedDocument>()
+    private val invertedIndex = linkedMapOf<String, MutableSet<String>>()
+
+    @Synchronized
+    override fun rebuild(documents: Collection<ImpressionSearchDocument>) {
+        this.documents.clear()
+        invertedIndex.clear()
+        documents.forEach(::upsertInternal)
+    }
+
+    @Synchronized
+    override fun upsert(document: ImpressionSearchDocument) {
+        removeByDocumentId(document.id)
+        upsertInternal(document)
+    }
+
+    @Synchronized
+    override fun removeByTarget(target: ImpressionSearchTarget) {
+        documents.values
+            .asSequence()
+            .filter { it.document.target == target }
+            .map { it.document.id }
+            .toList()
+            .forEach(::removeByDocumentId)
+    }
+
+    @Synchronized
+    override fun search(query: String, limit: Int): List<ImpressionSearchHit> {
+        if (limit <= 0) {
+            return emptyList()
+        }
+
+        val normalizedQuery = normalize(query)
+        if (normalizedQuery.isBlank()) {
+            return emptyList()
+        }
+
+        val queryTerms = tokenizer.tokenize(normalizedQuery)
+        val candidateIds = if (queryTerms.isEmpty()) {
+            documents.keys.toSet()
+        } else {
+            queryTerms
+                .asSequence()
+                .flatMap { invertedIndex[it].orEmpty().asSequence() }
+                .toSet()
+        }
+
+        return candidateIds
+            .asSequence()
+            .mapNotNull { documentId -> scoreDocument(documents[documentId] ?: return@mapNotNull null, normalizedQuery, queryTerms) }
+            .filter { it.score > 0.0 }
+            .sortedWith(compareByDescending<ImpressionSearchHit> { it.score }.thenBy { it.document.id })
+            .take(limit)
+            .toList()
+    }
+
+    private fun upsertInternal(document: ImpressionSearchDocument) {
+        val normalizedText = normalize(document.text)
+        val terms = tokenizer.tokenize(normalizedText)
+        val indexedDocument = IndexedDocument(document, normalizedText, terms)
+        documents[document.id] = indexedDocument
+        terms.forEach { term ->
+            invertedIndex.getOrPut(term) { linkedSetOf() }.add(document.id)
+        }
+    }
+
+    private fun removeByDocumentId(documentId: String) {
+        val indexedDocument = documents.remove(documentId) ?: return
+        indexedDocument.terms.forEach { term ->
+            val ids = invertedIndex[term] ?: return@forEach
+            ids.remove(documentId)
+            if (ids.isEmpty()) {
+                invertedIndex.remove(term)
+            }
+        }
+    }
+
+    private fun scoreDocument(
+        indexedDocument: IndexedDocument,
+        normalizedQuery: String,
+        queryTerms: Set<String>,
+    ): ImpressionSearchHit? {
+        val matchedTerms = if (queryTerms.isEmpty()) {
+            emptySet()
+        } else {
+            queryTerms.intersect(indexedDocument.terms)
+        }
+        val exactPhraseMatched = indexedDocument.normalizedText.contains(normalizedQuery)
+
+        if (matchedTerms.isEmpty() && !exactPhraseMatched) {
+            return null
+        }
+
+        val coverage = if (queryTerms.isEmpty()) 0.0 else matchedTerms.size.toDouble() / queryTerms.size.toDouble()
+        val termScore = matchedTerms.size.toDouble()
+        val exactPhraseBonus = if (exactPhraseMatched) EXACT_PHRASE_BONUS else 0.0
+        val fieldBonus = fieldBonus(indexedDocument.document.field)
+        val score = (termScore + coverage + exactPhraseBonus + fieldBonus) * indexedDocument.document.weight
+
+        return ImpressionSearchHit(
+            document = indexedDocument.document,
+            score = score,
+            matchedTerms = matchedTerms,
+        )
+    }
+
+    private fun fieldBonus(field: ImpressionSearchField): Double = when (field) {
+        ImpressionSearchField.SUBJECT -> 0.8
+        ImpressionSearchField.FEATURE -> 0.35
+        ImpressionSearchField.IMPRESSION -> 0.25
+        ImpressionSearchField.RELATION -> 0.15
+        ImpressionSearchField.EVIDENCE -> 0.0
+    }
+
+    private fun normalize(text: String): String =
+        text.lowercase()
+            .replace(WHITESPACE_REGEX, " ")
+            .trim()
+
+    private data class IndexedDocument(
+        val document: ImpressionSearchDocument,
+        val normalizedText: String,
+        val terms: Set<String>,
+    )
+
+    companion object {
+        private const val EXACT_PHRASE_BONUS = 1.5
+        private val WHITESPACE_REGEX = Regex("\\s+")
+    }
+}
diff --git a/Partner-Core/src/test/java/work/slhaf/partner/core/cognition/impression/search/SimpleTextSearchTest.kt b/Partner-Core/src/test/java/work/slhaf/partner/core/cognition/impression/search/SimpleTextSearchTest.kt
new file mode 100644
index 00000000..3dcf73d7
--- /dev/null
+++ b/Partner-Core/src/test/java/work/slhaf/partner/core/cognition/impression/search/SimpleTextSearchTest.kt
@@ -0,0 +1,226 @@
+package work.slhaf.partner.core.cognition.impression.search
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+import work.slhaf.partner.core.cognition.impression.ActiveEntity
+
+class SimpleTextSearchTest {
+
+    @Test
+    fun `search ranks subject hit before evidence hit when both match similar terms`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val targetA = activeTarget("a")
+        val targetB = activeTarget("b")
+
+        search.rebuild(
+            listOf(
+                document("a-subject", targetA, ImpressionSearchField.SUBJECT, "城南旧书店老板", 1.0),
+                document("b-evidence", targetB, ImpressionSearchField.EVIDENCE, "用户提到城南旧书店附近有一家打印店", 0.8),
+            )
+        )
+
+        val hits = search.search("城南旧书店", limit = 10)
+
+        assertEquals(listOf("a-subject", "b-evidence"), hits.map { it.document.id })
+        assertTrue(hits.first().score > hits[1].score)
+        assertTrue(hits.first().matchedTerms.containsAll(setOf("城南", "旧书店")))
+    }
+
+    @Test
+    fun `exact phrase match can beat partial subject match`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val partialSubject = activeTarget("partial")
+        val exactEvidence = activeTarget("exact")
+
+        search.rebuild(
+            listOf(
+                document("partial-subject", partialSubject, ImpressionSearchField.SUBJECT, "工程教材", 1.0),
+                document("exact-evidence", exactEvidence, ImpressionSearchField.EVIDENCE, "旧书店老板推荐过工程教材", 0.8),
+            )
+        )
+
+        val hits = search.search("旧书店老板推荐过工程教材", limit = 10)
+
+        assertEquals("exact-evidence", hits.first().document.id)
+        assertTrue(hits.first().matchedTerms.containsAll(setOf("旧书店", "老板", "推荐", "工程", "教材")))
+    }
+
+    @Test
+    fun `search recalls bookstore owner from generated active entity documents`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val bookstoreOwner = activeEntity("bookstore", "城南旧书店老板") {
+            addEvidence("用户上周提到城南旧书店老板推荐过一本水利工程教材")
+            addProjectedFeatures("熟悉工程类旧书" to 0.9)
+        }
+        val technicalPartner = activeEntity("technical", "Java 技术搭子") {
+            addEvidence("用户正在讨论 Jieba 分词、SimpleTextSearch 和倒排索引")
+            addProjectedFeatures("熟悉 Kotlin 与检索实现" to 0.9)
+        }
+        val reportRoommate = activeEntity("report", "实验报告室友") {
+            addEvidence("用户帮室友整理 Vivado 进阶仿真实验报告模板和 docx 文件")
+        }
+
+        search.rebuild(
+            listOf(bookstoreOwner, technicalPartner, reportRoommate)
+                .flatMap(ImpressionSearchDocuments::fromActiveEntity)
+        )
+
+        val hits = search.search("旧书店老板推荐的工程教材", limit = 10)
+
+        assertFalse(hits.isEmpty())
+        assertEquals("bookstore", hits.first().document.target.id)
+    }
+
+    @Test
+    fun `search recalls technical active entity from implementation terms`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val technicalPartner = activeEntity("technical", "Java 技术搭子") {
+            addEvidence("用户正在讨论 Jieba 分词、SimpleTextSearch 和倒排索引")
+            addProjectedImpressions("需要补充搜索召回测试" to 0.8)
+        }
+        val reportRoommate = activeEntity("report", "实验报告室友") {
+            addEvidence("用户帮室友整理 Vivado 进阶仿真实验报告模板和 docx 文件")
+        }
+
+        search.rebuild(
+            listOf(technicalPartner, reportRoommate)
+                .flatMap(ImpressionSearchDocuments::fromActiveEntity)
+        )
+
+        val hits = search.search("jieba 分词 SimpleTextSearch 倒排索引", limit = 10)
+
+        assertFalse(hits.isEmpty())
+        assertEquals("technical", hits.first().document.target.id)
+    }
+
+    @Test
+    fun `search recalls report active entity from document task terms`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val technicalPartner = activeEntity("technical", "Java 技术搭子") {
+            addEvidence("用户正在讨论 Kotlin、Jieba 分词和 SimpleTextSearch")
+        }
+        val reportRoommate = activeEntity("report", "实验报告室友") {
+            addEvidence("用户帮室友整理 Vivado 进阶仿真实验报告模板和 docx 文件")
+        }
+
+        search.rebuild(
+            listOf(technicalPartner, reportRoommate)
+                .flatMap(ImpressionSearchDocuments::fromActiveEntity)
+        )
+
+        val hits = search.search("Vivado 实验报告模板", limit = 10)
+
+        assertFalse(hits.isEmpty())
+        assertEquals("report", hits.first().document.target.id)
+    }
+
+    @Test
+    fun `upsert replaces previous index terms for the same document id`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val target = activeTarget("entity")
+
+        search.upsert(document("doc", target, ImpressionSearchField.EVIDENCE, "旧书店老板", 1.0))
+        assertEquals(listOf("doc"), search.search("老板", limit = 10).map { it.document.id })
+
+        search.upsert(document("doc", target, ImpressionSearchField.EVIDENCE, "实验报告模板", 1.0))
+
+        assertTrue(search.search("老板", limit = 10).isEmpty())
+        assertEquals(listOf("doc"), search.search("实验报告", limit = 10).map { it.document.id })
+    }
+
+    @Test
+    fun `removeByTarget removes all documents belonging to that target`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val removed = activeTarget("removed")
+        val kept = activeTarget("kept")
+
+        search.rebuild(
+            listOf(
+                document("removed-subject", removed, ImpressionSearchField.SUBJECT, "旧书店老板", 1.0),
+                document("removed-evidence", removed, ImpressionSearchField.EVIDENCE, "工程教材", 0.8),
+                document("kept-evidence", kept, ImpressionSearchField.EVIDENCE, "实验报告模板", 0.8),
+            )
+        )
+
+        search.removeByTarget(removed)
+
+        val hits = search.search("实验报告", limit = 10)
+        assertEquals(listOf("kept-evidence"), hits.map { it.document.id })
+        assertFalse(hits.any { it.document.target == removed })
+        assertTrue(search.search("旧书店", limit = 10).isEmpty())
+    }
+
+    @Test
+    fun `rebuild clears previous documents and index terms`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val target = activeTarget("entity")
+
+        search.rebuild(listOf(document("old", target, ImpressionSearchField.SUBJECT, "旧书店老板", 1.0)))
+        assertEquals(listOf("old"), search.search("老板", limit = 10).map { it.document.id })
+
+        search.rebuild(listOf(document("new", target, ImpressionSearchField.SUBJECT, "实验报告模板", 1.0)))
+
+        assertTrue(search.search("老板", limit = 10).isEmpty())
+        assertEquals(listOf("new"), search.search("实验报告", limit = 10).map { it.document.id })
+    }
+
+    @Test
+    fun `blank unmatched and zero limit queries return empty hits`() {
+        val search = SimpleTextSearch(TestTokenizer())
+        val target = activeTarget("entity")
+        search.rebuild(listOf(document("doc", target, ImpressionSearchField.SUBJECT, "旧书店老板", 1.0)))
+
+        assertTrue(search.search("   ", limit = 10).isEmpty())
+        assertTrue(search.search("完全不存在", limit = 10).isEmpty())
+        assertTrue(search.search("旧书店", limit = 0).isEmpty())
+    }
+
+    private fun activeTarget(id: String) =
+        ImpressionSearchTarget(ImpressionSearchTarget.Type.ACTIVE_ENTITY, id)
+
+    private fun activeEntity(
+        runtimeId: String,
+        subject: String,
+        configure: ActiveEntity.() -> Unit,
+    ): ActiveEntity = ActiveEntity(runtimeId = runtimeId).apply {
+        updateSubject(subject)
+        configure()
+    }
+
+    private fun document(
+        id: String,
+        target: ImpressionSearchTarget,
+        field: ImpressionSearchField,
+        text: String,
+        weight: Double,
+    ) = ImpressionSearchDocument(
+        id = id,
+        target = target,
+        field = field,
+        text = text,
+        weight = weight,
+    )
+
+    private class TestTokenizer : ImpressionTokenizer {
+        private val dictionary = listOf(
+            "城南", "旧书店", "老板", "推荐", "工程", "教材", "水利", "熟悉", "旧书",
+            "java", "kotlin", "jieba", "分词", "simpletextsearch", "倒排", "索引", "检索", "测试", "召回",
+            "vivado", "实验报告", "实验", "报告", "模板", "docx", "室友", "整理", "文件"
+        )
+        private val alphaNumericRegex = Regex("[a-z0-9]+(?:[-_./][a-z0-9]+)*")
+
+        override fun tokenize(text: String): Set<String> {
+            val normalized = text.lowercase().trim()
+            if (normalized.isBlank()) {
+                return emptySet()
+            }
+
+            return buildSet {
+                dictionary.filterTo(this) { normalized.contains(it) }
+                alphaNumericRegex.findAll(normalized).mapTo(this) { it.value }
+            }
+        }
+    }
+}