diff --git a/internal/ingestion/component/chunker/group.go b/internal/ingestion/component/chunker/group.go
index d69924735b..21fb0082e0 100644
--- a/internal/ingestion/component/chunker/group.go
+++ b/internal/ingestion/component/chunker/group.go
@@ -36,6 +36,8 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"regexp"
+	"sort"
 	"strings"
 
 	"go.uber.org/zap"
@@ -115,7 +117,7 @@ func invokeGroup(_ context.Context, inputs map[string]any, p *titleChunkerParam)
 	if len(records) == 0 {
 		return emptyOutputs(), nil
 	}
-	ctx := newLevelContext(records, p)
+	ctx := newLevelContext(records, outlineFromInputs(inputs), p)
 	levels := ctx.Levels()
 	// Count heading level distribution for debugging.
 	headingCounts := make(map[int]int)
@@ -256,7 +258,10 @@ func buildChunksFromRecordGroups(groups [][]lineRecord, p *titleChunkerParam, pl
 		if len(g) == 0 {
 			continue
 		}
-		chunk := map[string]any{"text": joinGroupText(g)}
+		// Strip parser-emitted position tags (`@@...##`) from the
+		// joined text (diff 1.6 / 2.8). Mirrors common.py:255
+		// `RAGFlowPdfParser.remove_tag("".join(...))`.
+		chunk := map[string]any{"text": removeTag(joinGroupText(g))}
 		if !plain {
 			first := g[0]
 			if first.docType != "" {
@@ -266,6 +271,24 @@ func buildChunksFromRecordGroups(groups [][]lineRecord, p *titleChunkerParam, pl
 				chunk["img_id"] = *first.imgID
 			}
 		}
+		// Merge PDF coordinate matrices across the merged records
+		// instead of keeping only the leading record's (diff 1.6).
+		// Mirrors pdf_chunk_metadata.py:127 merge_pdf_positions.
+		var pdfSrc, posSrc []json.RawMessage
+		for _, r := range g {
+			if len(r.pdfPositions) > 0 {
+				pdfSrc = append(pdfSrc, r.pdfPositions)
+			}
+			if len(r.positions) > 0 {
+				posSrc = append(posSrc, r.positions)
+			}
+		}
+		if m := mergePositionMatrix(pdfSrc...); m != nil {
+			chunk["_pdf_positions"] = m
+		}
+		if m := mergePositionMatrix(posSrc...); m != nil {
+			chunk["positions"] = m
+		}
 		chunks = append(chunks, chunk)
 	}
 	if p.RootChunkAsHeading && len(chunks) > 1 {
@@ -278,6 +301,61 @@ func buildChunksFromRecordGroups(groups [][]lineRecord, p *titleChunkerParam, pl
 	return chunks
 }
 
+// posTagRemove matches parser-emitted position tags of the form
+// `@@<page>\t<left>\t<right>\t<top>\t<bottom>##`. Mirrors Python
+// pdf_parser.py:1934 `re.sub(r"@@[\t0-9.-]+?##", "", txt)`.
+var posTagRemove = regexp.MustCompile(`@@[\t0-9.-]+?##`)
+
+// removeTag strips parser-emitted position tags from a chunk's text.
+// Mirrors deepdoc RAGFlowPdfParser.remove_tag.
+func removeTag(text string) string {
+	return posTagRemove.ReplaceAllString(text, "")
+}
+
+// mergePositionMatrix aggregates multiple PDF coordinate matrices into a
+// single de-duplicated, sorted matrix. Mirrors Python
+// pdf_chunk_metadata.py:127 merge_pdf_positions: rows are 5-tuples
+// [page,left,right,top,bottom]; duplicates (by the first five columns)
+// are dropped and rows are sorted by (page, top, left). Returns nil when
+// no source carries any usable coordinates.
+func mergePositionMatrix(sources ...json.RawMessage) [][]float64 {
+	var out [][]float64
+	seen := make(map[string]bool)
+	for _, src := range sources {
+		if len(src) == 0 {
+			continue
+		}
+		var mat [][]float64
+		if err := json.Unmarshal(src, &mat); err != nil {
+			continue
+		}
+		for _, row := range mat {
+			if len(row) < 5 {
+				continue
+			}
+			key := fmt.Sprintf("%v|%v|%v|%v|%v", row[0], row[1], row[2], row[3], row[4])
+			if seen[key] {
+				continue
+			}
+			seen[key] = true
+			out = append(out, row)
+		}
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	sort.Slice(out, func(i, j int) bool {
+		if out[i][0] != out[j][0] {
+			return out[i][0] < out[j][0]
+		}
+		if out[i][3] != out[j][3] {
+			return out[i][3] < out[j][3]
+		}
+		return out[i][1] < out[j][1]
+	})
+	return out
+}
+
 // extractLineRecords reads the chunker inputs in the same order the
 // python BaseTitleChunker.extract_line_records uses:
 //
@@ -333,12 +411,14 @@ func recordsFromStructured(items []schema.ChunkDoc) []lineRecord {
 			meta[k] = json.RawMessage(v)
 		}
 		out = append(out, lineRecord{
-			text:       text,
-			docType:    dt,
-			imgID:      imgID,
-			layout:     it.Layout,
-			ckType:     it.CKType,
-			parentMeta: meta,
+			text:         text,
+			docType:      dt,
+			imgID:        imgID,
+			layout:       it.Layout,
+			ckType:       it.CKType,
+			pdfPositions: it.PDFPositions,
+			positions:    it.Positions,
+			parentMeta:   meta,
 		})
 	}
 	return out
diff --git a/internal/ingestion/component/chunker/group_test.go b/internal/ingestion/component/chunker/group_test.go
index 2cb1ebae6e..3fe0c3b835 100644
--- a/internal/ingestion/component/chunker/group_test.go
+++ b/internal/ingestion/component/chunker/group_test.go
@@ -18,6 +18,7 @@ package chunker
 
 import (
 	"context"
+	"strings"
 	"testing"
 
 	"ragflow/internal/agent/runtime"
@@ -230,6 +231,59 @@ func TestGroupChunker_StructuredMetadata(t *testing.T) {
 	}
 }
 
+// TestGroupChunker_MergesPDFPositionsAndRemovesTags is the TDD test for
+// migration diffs Chunker-1.6 / 2.8: when the group chunker merges
+// multiple adjacent text records into one chunk it must (a) strip the
+// parser-emitted `@@...##` position tags from the joined text, and
+// (b) MERGE (not drop) the `positions` coordinate matrices across the
+// merged records — mirroring common.py:255 remove_tag + merge.
+func TestGroupChunker_MergesPDFPositionsAndRemovesTags(t *testing.T) {
+	c, err := NewGroupTitleChunker(map[string]any{
+		"levels": [][]string{{`^# `}},
+	})
+	if err != nil {
+		t.Fatalf("NewGroupTitleChunker: %v", err)
+	}
+	items := []map[string]any{
+		{"text": "# Heading", "doc_type_kwd": "text"},
+		{"text": "body one @@1\t10.0\t20.0\t30.0\t40.0## tail", "doc_type_kwd": "text", "positions": [][]float64{{1, 10, 20, 30, 40}}},
+		{"text": "body two @@2\t15.0\t25.0\t35.0\t45.0## tail", "doc_type_kwd": "text", "positions": [][]float64{{2, 15, 25, 35, 45}}},
+	}
+	out, err := c.Invoke(context.Background(), map[string]any{
+		"name":          "doc",
+		"output_format": "chunks",
+		"chunks":        items,
+	})
+	if err != nil {
+		t.Fatalf("Invoke: %v", err)
+	}
+	chunks, _ := out["chunks"].([]map[string]any)
+	if len(chunks) == 0 {
+		t.Fatal("no chunks emitted")
+	}
+	for _, ck := range chunks {
+		text, _ := ck["text"].(string)
+		// Only the merged body group carries both bodies.
+		if !strings.Contains(text, "body one") || !strings.Contains(text, "body two") {
+			continue
+		}
+		// (a) parser tags must be stripped from the text.
+		if strings.Contains(text, "@@") {
+			t.Errorf("parser position tags leaked into chunk text: %q", text)
+		}
+		// (b) positions must be merged across both records.
+		pos, ok := ck["positions"].([][]float64)
+		if !ok {
+			t.Fatalf("positions missing or wrong type %T on merged group chunk", ck["positions"])
+		}
+		if len(pos) != 2 {
+			t.Errorf("merged positions = %d groups, want 2 (both records)", len(pos))
+		}
+		return
+	}
+	t.Fatal("merged body group chunk not found in output")
+}
+
 func TestGroupTitleChunker_InvokeDeterministic(t *testing.T) {
 	c, err := NewGroupTitleChunker(map[string]any{
 		"levels": [][]string{
diff --git a/internal/ingestion/component/chunker/hierarchy.go b/internal/ingestion/component/chunker/hierarchy.go
index 79f81e3dce..a659b8b34c 100644
--- a/internal/ingestion/component/chunker/hierarchy.go
+++ b/internal/ingestion/component/chunker/hierarchy.go
@@ -148,7 +148,7 @@ func invokeHierarchy(_ context.Context, inputs map[string]any, p *titleChunkerPa
 	if len(records) == 0 {
 		return emptyOutputs(), nil
 	}
-	ctx := newLevelContext(records, p)
+	ctx := newLevelContext(records, outlineFromInputs(inputs), p)
 	levels := ctx.Levels()
 	// Count heading level distribution for debugging.
 	headingCounts := make(map[int]int)
diff --git a/internal/ingestion/component/chunker/pdfcrop_cgo.go b/internal/ingestion/component/chunker/pdfcrop_cgo.go
index 9bdf0d1d47..ce0768b4af 100644
--- a/internal/ingestion/component/chunker/pdfcrop_cgo.go
+++ b/internal/ingestion/component/chunker/pdfcrop_cgo.go
@@ -53,7 +53,9 @@ func newPDFEngineFromUpstream(ctx context.Context, up schema.ChunkerFromUpstream
 	return deepdocpdf.NewEngine(data)
 }
 
-// cropImageChunks crops image/table chunks in place. Each spanned page is
+// cropImageChunks crops image/table chunks and renders text previews (for
+// text chunks that carry PDF positions, mirroring Python
+// restore_pdf_text_previews). Each spanned page is
 // rendered at most once. Chunks arrive in document order, so we keep only a
 // sliding window of page images: once we advance past a chunk whose minimum
 // page is P, no later chunk references a page < P, and we evict those entries
@@ -139,9 +141,14 @@ func cropImageChunks(ctx context.Context, engine deepdoctype.PDFEngine, chunks [
 	return out
 }
 
+// needsCrop reports whether a chunk should be cropped to a page-region
+// preview from its PDF positions. Image/table chunks get their media region
+// cropped; text chunks with positions get a rendered preview of the text
+// region (Python restore_pdf_text_previews). A pre-existing Image is never
+// re-cropped — cropImageChunks honors that separately.
 func needsCrop(ck schema.ChunkDoc) bool {
 	switch ck.CKType {
-	case "image", "table":
+	case "image", "table", "text":
 		return len(ck.PDFPositions) > 0 || len(ck.Positions) > 0
 	default:
 		return false
diff --git a/internal/ingestion/component/chunker/pdfcrop_cgo_test.go b/internal/ingestion/component/chunker/pdfcrop_cgo_test.go
index ec91980020..613d0ac11c 100644
--- a/internal/ingestion/component/chunker/pdfcrop_cgo_test.go
+++ b/internal/ingestion/component/chunker/pdfcrop_cgo_test.go
@@ -71,7 +71,7 @@ func TestNeedsCrop(t *testing.T) {
 	}{
 		{"image with positions", schema.ChunkDoc{CKType: "image", PDFPositions: jsonPositions(t, []float64{1, 10, 100, 10, 100})}, true},
 		{"table with positions", schema.ChunkDoc{CKType: "table", Positions: jsonPositions(t, []float64{1, 10, 100, 10, 100})}, true},
-		{"text with positions", schema.ChunkDoc{CKType: "text", PDFPositions: jsonPositions(t, []float64{1, 10, 100, 10, 100})}, false},
+		{"text with positions", schema.ChunkDoc{CKType: "text", PDFPositions: jsonPositions(t, []float64{1, 10, 100, 10, 100})}, true},
 		{"image without positions", schema.ChunkDoc{CKType: "image"}, false},
 		{"unknown type", schema.ChunkDoc{CKType: "equation", PDFPositions: jsonPositions(t, []float64{1, 10, 100, 10, 100})}, false},
 	}
@@ -82,7 +82,7 @@ func TestNeedsCrop(t *testing.T) {
 	}
 }
 
-func TestCropImageChunks_CropsImageAndTable(t *testing.T) {
+func TestCropImageChunks_CropsImageTableAndText(t *testing.T) {
 	ctx := context.Background()
 	// 1-based JSON position (1) must be rendered as 0-based page 0.
 	eng := assertZeroPageEngine{}
@@ -91,7 +91,7 @@ func TestCropImageChunks_CropsImageAndTable(t *testing.T) {
 	chunks := []schema.ChunkDoc{
 		{CKType: "image", PDFPositions: pos},
 		{CKType: "table", PDFPositions: pos},
-		{CKType: "text", PDFPositions: pos},                           // skipped (not image/table)
+		{CKType: "text", PDFPositions: pos},                           // restored preview (Chunker-1.3)
 		{CKType: "image", Image: "data:image/png;base64,preexisting"}, // preserved
 	}
 	out := cropImageChunks(ctx, eng, chunks)
@@ -101,8 +101,10 @@ func TestCropImageChunks_CropsImageAndTable(t *testing.T) {
 	for i, ck := range out {
 		switch ck.CKType {
 		case "text":
-			if ck.Image != "" {
-				t.Errorf("chunk %d (text): image should stay empty, got %q", i, ck.Image)
+			// Chunker-1.3: text chunks with PDF positions get a rendered
+			// preview, mirroring Python restore_pdf_text_previews.
+			if !strings.HasPrefix(ck.Image, "data:image/png;base64,") {
+				t.Errorf("chunk %d (text): image = %q, want data:image/png;base64, prefix (preview restored)", i, ck.Image)
 			}
 		case "image":
 			if ck.Image == "data:image/png;base64,preexisting" {
@@ -119,6 +121,30 @@ func TestCropImageChunks_CropsImageAndTable(t *testing.T) {
 	}
 }
 
+// TestRestorePDFTextPreview covers Chunker-1.3 directly: a text chunk that
+// carries PDF positions must receive a rendered preview image, while a text
+// chunk without positions must be left untouched (no spurious preview). The
+// img_id upload is owned by imageUploadDecorator (image_upload.go) and is
+// not asserted here.
+func TestRestorePDFTextPreview(t *testing.T) {
+	ctx := context.Background()
+	pos := jsonPositions(t, []float64{1, 10, 100, 10, 100})
+
+	withPos := schema.ChunkDoc{CKType: "text", PDFPositions: pos}
+	withoutPos := schema.ChunkDoc{CKType: "text", Text: "plain text, no coordinates"}
+
+	out := cropImageChunks(ctx, mockCropEngine{}, []schema.ChunkDoc{withPos, withoutPos})
+	if len(out) != 2 {
+		t.Fatalf("len(out) = %d, want 2", len(out))
+	}
+	if !strings.HasPrefix(out[0].Image, "data:image/png;base64,") {
+		t.Errorf("chunk with positions: image = %q, want data:image/png;base64, prefix", out[0].Image)
+	}
+	if out[1].Image != "" {
+		t.Errorf("chunk without positions: image = %q, want empty", out[1].Image)
+	}
+}
+
 func TestCropImageChunks_NilEnginePassesThrough(t *testing.T) {
 	ctx := context.Background()
 	pos := jsonPositions(t, []float64{1, 10, 100, 10, 100})
diff --git a/internal/ingestion/component/chunker/title.go b/internal/ingestion/component/chunker/title.go
index 8c06bf8b40..791a962dad 100644
--- a/internal/ingestion/component/chunker/title.go
+++ b/internal/ingestion/component/chunker/title.go
@@ -54,6 +54,7 @@ package chunker
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"regexp"
 	"strings"
@@ -261,8 +262,9 @@ func matchLayoutLevel(text, layout string, fallbackLevel int) int {
 
 // resolveTitleLevels mirrors common.py:resolve_frequency_levels over the
 // full record stream. It is the "frequency" branch of
-// common.py:resolve_title_levels (the outline branch is parity-gap
-// territory per the SCOPE comment above).
+// common.py:resolve_title_levels. The outline branch
+// (common.py:resolve_outline_levels) is handled by resolveOutlineLevels and
+// tried first in newLevelContext.
 //
 // For each record:
 //   - a non-text record is pinned to BODY_LEVEL directly (python skips
@@ -339,6 +341,140 @@ func resolveTitleLevels(records []lineRecord, p *titleChunkerParam) []int {
 	return out
 }
 
+// outlineEntry is one PDF bookmark/heading from the parser-supplied
+// outline, mirroring Python extract_pdf_outlines' (text, level, page)
+// tuple. The page is unused by title detection.
+type outlineEntry struct {
+	title string
+	level int
+}
+
+// outlineSimilarity mirrors common.py:_outline_similarity: the Jaccard
+// overlap of character bigrams between two strings. It is rune-based so it
+// matches Python's code-point indexing (str[i] is a Unicode character, not
+// a byte). The right-hand bigram set is capped at min(len(left), len(right)-1)
+// characters, exactly as the Python range() does.
+func outlineSimilarity(left, right string) float64 {
+	lr := []rune(left)
+	rr := []rune(right)
+	leftPairs := make(map[string]struct{}, max(0, len(lr)-1))
+	for i := 0; i+1 < len(lr); i++ {
+		leftPairs[string(lr[i])+string(lr[i+1])] = struct{}{}
+	}
+	n := len(lr)
+	if m := len(rr) - 1; m < n {
+		n = m
+	}
+	if n < 0 {
+		n = 0
+	}
+	rightPairs := make(map[string]struct{}, n)
+	for i := 0; i < n; i++ {
+		rightPairs[string(rr[i])+string(rr[i+1])] = struct{}{}
+	}
+	denom := len(leftPairs)
+	if len(rightPairs) > denom {
+		denom = len(rightPairs)
+	}
+	if denom == 0 {
+		return 0
+	}
+	inter := 0
+	for k := range leftPairs {
+		if _, ok := rightPairs[k]; ok {
+			inter++
+		}
+	}
+	return float64(inter) / float64(denom)
+}
+
+// resolveOutlineLevels mirrors common.py:resolve_outline_levels. Each text
+// record is matched against the outline by character-bigram similarity (>0.8
+// assigns level+1); unmatched records stay BODY_LEVEL. It returns ok=false
+// when there is no outline, or when the outline is too sparse relative to the
+// record count (len(outlines)/len(records) <= 0.03), in which case the
+// caller falls back to frequency-based detection. mostLevel mirrors Python's
+// max(1, max_outline_level).
+func resolveOutlineLevels(records []lineRecord, outline []outlineEntry) (levels []int, mostLevel int, ok bool) {
+	if len(outline) == 0 || len(records) == 0 {
+		return nil, 0, false
+	}
+	if float64(len(outline))/float64(len(records)) <= 0.03 {
+		return nil, 0, false
+	}
+	maxLevel := 0
+	for _, o := range outline {
+		if o.level > maxLevel {
+			maxLevel = o.level
+		}
+	}
+	levels = make([]int, len(records))
+	for i, rec := range records {
+		if !rec.isText() {
+			levels[i] = bodyLevel
+			continue
+		}
+		matched := 0
+		for _, o := range outline {
+			if outlineSimilarity(o.title, rec.text) > 0.8 {
+				matched = o.level + 1
+				break
+			}
+		}
+		if matched == 0 {
+			levels[i] = bodyLevel
+		} else {
+			levels[i] = matched
+		}
+	}
+	return levels, max(1, maxLevel), true
+}
+
+// outlineFromInputs reads the parser-supplied PDF outline from the upstream
+// file metadata (file.outline, written by the ingestion PDF parser's
+// outlinesToFileMeta) and normalizes it into the chunker's outlineEntry
+// shape. Returns nil when no outline is present, so callers fall back to
+// frequency-based title detection. Numbers are coerced from int/float64
+// because the runtime may hand the chunker a JSON-decoded payload.
+func outlineFromInputs(inputs map[string]any) []outlineEntry {
+	file, _ := inputs["file"].(map[string]any)
+	if file == nil {
+		return nil
+	}
+	raw, _ := file["outline"].([]any)
+	if len(raw) == 0 {
+		return nil
+	}
+	out := make([]outlineEntry, 0, len(raw))
+	for _, item := range raw {
+		m, ok := item.(map[string]any)
+		if !ok {
+			continue
+		}
+		title, _ := m["title"].(string)
+		if title == "" {
+			continue
+		}
+		out = append(out, outlineEntry{title: title, level: anyToInt(m["level"])})
+	}
+	return out
+}
+
+func anyToInt(v any) int {
+	switch t := v.(type) {
+	case int:
+		return t
+	case int64:
+		return int(t)
+	case float64:
+		return int(t)
+	case float32:
+		return int(t)
+	default:
+		return 0
+	}
+}
+
 // bodyLevel is the sentinel python uses for non-heading lines. We use
 // the same large int (sys.maxsize - 1) for parity. Practically this
 // just needs to be "larger than any realistic heading level"; tests
@@ -357,11 +493,12 @@ func lineRecordsFromText(text string) []lineRecord {
 			continue
 		}
 		out = append(out, lineRecord{
-			text:    ln,
-			docType: "text",
-			imgID:   nil,
-			layout:  "",
-			pdfPos:  nil,
+			text:         ln,
+			docType:      "text",
+			imgID:        nil,
+			layout:       "",
+			pdfPositions: nil,
+			positions:    nil,
 		})
 	}
 	return out
@@ -371,13 +508,14 @@ func lineRecordsFromText(text string) []lineRecord {
 // common.py:extract_line_records yields. Used by Group/Hierarchy
 // chunk-builders.
 type lineRecord struct {
-	text       string
-	docType    string
-	imgID      *string
-	layout     string
-	ckType     string
-	pdfPos     []map[string]any
-	parentMeta map[string]any
+	text         string
+	docType      string
+	imgID        *string
+	layout       string
+	ckType       string
+	pdfPositions json.RawMessage
+	positions    json.RawMessage
+	parentMeta   map[string]any
 }
 
 func (r lineRecord) textOrEmpty() string { return r.text }
@@ -421,7 +559,13 @@ type LevelContext struct {
 	mostLevel int
 }
 
-func newLevelContext(records []lineRecord, p *titleChunkerParam) LevelContext {
+// newLevelContext resolves per-line heading levels, mirroring Python's
+// resolve_title_levels: try the PDF outline branch first (when an outline is
+// supplied and dense enough), otherwise fall back to frequency detection.
+func newLevelContext(records []lineRecord, outline []outlineEntry, p *titleChunkerParam) LevelContext {
+	if levels, mostLevel, ok := resolveOutlineLevels(records, outline); ok {
+		return LevelContext{levels: levels, mostLevel: mostLevel}
+	}
 	levels := resolveTitleLevels(records, p)
 	// most_level is the most-frequent non-body heading level
 	// (common.py:resolve_frequency_levels). Python computes this via
diff --git a/internal/ingestion/component/chunker/title_test.go b/internal/ingestion/component/chunker/title_test.go
index c8b39dd3c9..63f376d267 100644
--- a/internal/ingestion/component/chunker/title_test.go
+++ b/internal/ingestion/component/chunker/title_test.go
@@ -255,7 +255,7 @@ func TestNewLevelContext_MostLevelIsMode(t *testing.T) {
 		{text: "## c", docType: "text"},
 		{text: "### d", docType: "text"},
 	}
-	lc := newLevelContext(records, p)
+	lc := newLevelContext(records, nil, p)
 	// selectLevelGroup picks the single 3-pattern family; per-line
 	// levels are [1,2,2,3], so the mode (most frequent heading level)
 	// is level 2.
@@ -371,3 +371,99 @@ func TestResolveTitleLevels_LayoutFallback(t *testing.T) {
 		t.Errorf("plain body level = %d, want bodyLevel", levels[2])
 	}
 }
+
+// TestResolveOutlineLevels covers Chunker-1.5: a text line that matches a
+// PDF outline entry by character-bigram similarity (>0.8) is assigned the
+// outline level+1; lines that do not match stay BODY_LEVEL. The non-text
+// record is pinned to BODY_LEVEL regardless.
+func TestResolveOutlineLevels(t *testing.T) {
+	outline := []outlineEntry{
+		{title: "第一章 概述", level: 0},
+		{title: "第二章 方法", level: 1},
+	}
+	records := []lineRecord{
+		{text: "第一章 概述", docType: "text"},
+		{text: "本章介绍背景。", docType: "text"},         // no outline match
+		{text: "figure caption", docType: "image"}, // non-text
+	}
+	levels, mostLevel, ok := resolveOutlineLevels(records, outline)
+	if !ok {
+		t.Fatalf("resolveOutlineLevels ok = false, want true")
+	}
+	if levels[0] != 1 { // outline level 0 + 1
+		t.Errorf("matched line level = %d, want 1", levels[0])
+	}
+	if levels[1] != bodyLevel {
+		t.Errorf("unmatched body level = %d, want bodyLevel", levels[1])
+	}
+	if levels[2] != bodyLevel {
+		t.Errorf("non-text level = %d, want bodyLevel", levels[2])
+	}
+	if mostLevel != 1 { // max(1, max outline level 1)
+		t.Errorf("mostLevel = %d, want 1", mostLevel)
+	}
+}
+
+// TestResolveOutlineLevels_SparseGuard ensures a too-sparse outline (ratio
+// <= 0.03) is rejected so detection falls back to frequency branch.
+func TestResolveOutlineLevels_SparseGuard(t *testing.T) {
+	outline := []outlineEntry{{title: "唯一的章节标题", level: 0}}
+	// 100 body records: 1/100 = 0.01 <= 0.03 -> rejected.
+	records := make([]lineRecord, 100)
+	for i := range records {
+		records[i] = lineRecord{text: "body paragraph", docType: "text"}
+	}
+	if _, _, ok := resolveOutlineLevels(records, outline); ok {
+		t.Errorf("sparse outline ok = true, want false")
+	}
+	if _, _, ok := resolveOutlineLevels(records, nil); ok {
+		t.Errorf("nil outline ok = true, want false")
+	}
+}
+
+// TestNewLevelContext_OutlineBranch pins Chunker-1.5 end-to-end: when an
+// outline is supplied, newLevelContext prefers the outline branch over the
+// regex/frequency branch.
+func TestNewLevelContext_OutlineBranch(t *testing.T) {
+	p := &titleChunkerParam{TitleChunkerParam: schema.TitleChunkerParam{
+		Method: "group",
+		Levels: [][]string{{`^# `}},
+	}}
+	outline := []outlineEntry{{title: "前言", level: 0}}
+	records := []lineRecord{
+		{text: "前言", docType: "text"},      // matches outline -> level 1
+		{text: "普通正文段落。", docType: "text"}, // no outline -> BODY_LEVEL
+	}
+	lc := newLevelContext(records, outline, p)
+	if got := lc.Levels(); got[0] != 1 || got[1] != bodyLevel {
+		t.Errorf("outline levels = %v, want [1, bodyLevel]", got)
+	}
+}
+
+// TestOutlineFromInputs verifies the parser-supplied file.outline is parsed
+// into outlineEntry, tolerating float64-encoded levels (runtime JSON path).
+func TestOutlineFromInputs(t *testing.T) {
+	inputs := map[string]any{
+		"file": map[string]any{
+			"outline": []any{
+				map[string]any{"title": "第一章", "level": 0, "page_number": 1},
+				map[string]any{"title": "第二章", "level": 1, "page_number": 3},
+			},
+		},
+	}
+	out := outlineFromInputs(inputs)
+	if len(out) != 2 {
+		t.Fatalf("outline len = %d, want 2", len(out))
+	}
+	if out[0].title != "第一章" || out[0].level != 0 {
+		t.Errorf("entry 0 = %+v, want {第一章 0}", out[0])
+	}
+	if out[1].title != "第二章" || out[1].level != 1 {
+		t.Errorf("entry 1 = %+v, want {第二章 1}", out[1])
+	}
+
+	// No file / no outline -> nil (frequency fallback).
+	if got := outlineFromInputs(map[string]any{}); got != nil {
+		t.Errorf("empty inputs outline = %v, want nil", got)
+	}
+}
diff --git a/internal/ingestion/component/chunker/token.go b/internal/ingestion/component/chunker/token.go
index 975f36df16..60ea9337ba 100644
--- a/internal/ingestion/component/chunker/token.go
+++ b/internal/ingestion/component/chunker/token.go
@@ -46,10 +46,10 @@
 //     Media-context attachment is per-item sequential; merge is
 //     index-deterministic.
 //
-//   - No PDF/outline awareness (Python `restore_pdf_text_previews`).
-//     That depends on deepdoc/parser which is out of scope for this
-//     phase; the chunker accepts the parser-style structured JSON
-//     payload and runs the same logic against it.
+//   - PDF text previews (Python `restore_pdf_text_previews`) are
+//     generated on demand for text chunks that carry PDF positions:
+//     cropImageChunks crops the text region and writes a preview image,
+//     then imageUploadDecorator uploads it to img_id. See pdfcrop_cgo.go.
 package chunker
 
 import (
@@ -722,6 +722,12 @@ func mergeByTokenSizeFromJSON(perItem [][]schema.ChunkDoc, chunkTokens int, over
 				prev.Text = prev.Text + "\n" + ck.Text
 				prev.TKNums = intPtr(intValue(prev.TKNums) + tk)
 			}
+			// Preserve PDF coordinates across the merge: extend the
+			// coordinate lists instead of dropping the incoming item's
+			// positions. Mirrors Python token_chunker.py:240
+			// `merged[prev][PDF_POSITIONS_KEY].extend(...)` (diffs 2.5 / 2.3).
+			prev.PDFPositions = extendRawJSONArray(prev.PDFPositions, ck.PDFPositions)
+			prev.Positions = extendRawJSONArray(prev.Positions, ck.Positions)
 		}
 		perItem[idx] = merged
 	}
@@ -742,6 +748,14 @@ func cloneChunkDoc(in schema.ChunkDoc) schema.ChunkDoc {
 		v := *in.PageNumber
 		out.PageNumber = &v
 	}
+	// Deep-copy the coordinate byte slices so the clone does not alias
+	// the source's backing array (diff 2.5 defensive fix).
+	if in.PDFPositions != nil {
+		out.PDFPositions = append(json.RawMessage(nil), in.PDFPositions...)
+	}
+	if in.Positions != nil {
+		out.Positions = append(json.RawMessage(nil), in.Positions...)
+	}
 	if in.Extra != nil {
 		out.Extra = make(map[string]json.RawMessage, len(in.Extra))
 		for k, v := range in.Extra {
@@ -751,6 +765,33 @@ func cloneChunkDoc(in schema.ChunkDoc) schema.ChunkDoc {
 	return out
 }
 
+// extendRawJSONArray concatenates two JSON array payloads, mirroring
+// Python's `merged[prev][KEY].extend(current[KEY])`. Either operand may be
+// empty; the result is always a valid JSON array (or an empty raw message).
+// It is used to accumulate PDF coordinate lists (`_pdf_positions`,
+// `positions`) when text chunks are merged (diffs 2.5 / 2.3).
+func extendRawJSONArray(a, b json.RawMessage) json.RawMessage {
+	if len(a) == 0 {
+		return b
+	}
+	if len(b) == 0 {
+		return a
+	}
+	var arrA, arrB []json.RawMessage
+	if err := json.Unmarshal(a, &arrA); err != nil {
+		return b
+	}
+	if err := json.Unmarshal(b, &arrB); err != nil {
+		return a
+	}
+	arrA = append(arrA, arrB...)
+	out, err := json.Marshal(arrA)
+	if err != nil {
+		return a
+	}
+	return out
+}
+
 func flatten(perItem [][]schema.ChunkDoc) []schema.ChunkDoc {
 	var out []schema.ChunkDoc
 	for _, cs := range perItem {
diff --git a/internal/ingestion/component/chunker/token_pdfpos_test.go b/internal/ingestion/component/chunker/token_pdfpos_test.go
new file mode 100644
index 0000000000..0c348cf308
--- /dev/null
+++ b/internal/ingestion/component/chunker/token_pdfpos_test.go
@@ -0,0 +1,119 @@
+//
+//  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+//
+//  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 chunker
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"ragflow/internal/ingestion/component/schema"
+)
+
+// TestMergeByTokenSizeFromJSON_ExtendsPDFPositions is the TDD test for
+// migration diffs Chunker-2.5 / 2.3: when two JSON text items carrying
+// `_pdf_positions` / `positions` are merged into one chunk, the merged
+// chunk must extend (not drop) the coordinate lists — mirroring Python
+// token_chunker.py:240 `merged[prev][PDF_POSITIONS_KEY].extend(...)`.
+func TestMergeByTokenSizeFromJSON_ExtendsPDFPositions(t *testing.T) {
+	posA := json.RawMessage(`[[1,10,20,30,40]]`)
+	posB := json.RawMessage(`[[2,15,25,35,45]]`)
+	items := [][]schema.ChunkDoc{
+		{
+			{Text: "alpha", DocType: "text", CKType: "text", TKNums: intPtr(5), PDFPositions: posA},
+			{Text: "beta", DocType: "text", CKType: "text", TKNums: intPtr(5), PDFPositions: posB},
+		},
+	}
+	got := mergeByTokenSizeFromJSON(items, 128, 0)
+	merged := got[0]
+	if len(merged) != 1 {
+		t.Fatalf("want 1 merged chunk, got %d", len(merged))
+	}
+	combined := string(merged[0].PDFPositions)
+	if !strings.Contains(combined, "1,10,20,30,40") {
+		t.Errorf("merged chunk lost first item _pdf_positions: %s", combined)
+	}
+	if !strings.Contains(combined, "2,15,25,35,45") {
+		t.Errorf("merged chunk dropped second item _pdf_positions (not extended): %s", combined)
+	}
+}
+
+// TestMergeByTokenSizeFromJSON_ExtendsPositions covers the parallel
+// `positions` field (diff 2.3).
+func TestMergeByTokenSizeFromJSON_ExtendsPositions(t *testing.T) {
+	posA := json.RawMessage(`[[1,2,3]]`)
+	posB := json.RawMessage(`[[4,5,6]]`)
+	items := [][]schema.ChunkDoc{
+		{
+			{Text: "a", DocType: "text", CKType: "text", TKNums: intPtr(5), Positions: posA},
+			{Text: "b", DocType: "text", CKType: "text", TKNums: intPtr(5), Positions: posB},
+		},
+	}
+	got := mergeByTokenSizeFromJSON(items, 128, 0)
+	combined := string(got[0][0].Positions)
+	if !strings.Contains(combined, "1,2,3") || !strings.Contains(combined, "4,5,6") {
+		t.Errorf("merged chunk dropped/omitted `positions`: %s", combined)
+	}
+}
+
+// TestCloneChunkDoc_DeepCopiesPDFPositions ensures cloneChunkDoc does not
+// alias the underlying _pdf_positions / positions byte slices (diff 2.5
+// defensive fix).
+func TestCloneChunkDoc_DeepCopiesPDFPositions(t *testing.T) {
+	pos := json.RawMessage(`[[1,2,3,4,5]]`)
+	orig := schema.ChunkDoc{Text: "x", PDFPositions: pos, Positions: pos}
+	cp := cloneChunkDoc(orig)
+	// Mutate the source's backing array after the clone.
+	pos[0] = '9'
+	if string(cp.PDFPositions) != "[[1,2,3,4,5]]" {
+		t.Errorf("clone shares _pdf_positions backing array: %s", string(cp.PDFPositions))
+	}
+	if string(cp.Positions) != "[[1,2,3,4,5]]" {
+		t.Errorf("clone shares positions backing array: %s", string(cp.Positions))
+	}
+}
+
+// TestMergeByTokenSizeFromJSON_PositionsDecodeToMatrix verifies the
+// chunker-side contract for diff 1.4: preserved `positions` must decode
+// (via ChunkDoc.ToMap → decodeStructuredValue) to a [][]float64 matrix so
+// the downstream task-layer processChunkPositions → AddPositions can
+// convert it to page_num_int / top_int / position_int. The coordinate
+// conversion itself lives in internal/ingestion/task (processChunkPositions),
+// not in the chunker.
+func TestMergeByTokenSizeFromJSON_PositionsDecodeToMatrix(t *testing.T) {
+	posA := json.RawMessage(`[[1,2,3,4,5]]`)
+	posB := json.RawMessage(`[[6,7,8,9,10]]`)
+	items := [][]schema.ChunkDoc{
+		{
+			{Text: "a", DocType: "text", CKType: "text", TKNums: intPtr(5), Positions: posA},
+			{Text: "b", DocType: "text", CKType: "text", TKNums: intPtr(5), Positions: posB},
+		},
+	}
+	got := mergeByTokenSizeFromJSON(items, 128, 0)
+	m := got[0][0].ToMap()
+	raw, ok := m["positions"]
+	if !ok {
+		t.Fatal("positions missing from ToMap output")
+	}
+	matrix, ok := raw.([][]float64)
+	if !ok {
+		t.Fatalf("positions decoded to %T, want [][]float64", raw)
+	}
+	if len(matrix) != 2 {
+		t.Fatalf("positions matrix has %d groups, want 2 (both merged items)", len(matrix))
+	}
+}
diff --git a/internal/ingestion/component/tokenizer_unit_test.go b/internal/ingestion/component/tokenizer_unit_test.go
index 403799740f..4710044a08 100644
--- a/internal/ingestion/component/tokenizer_unit_test.go
+++ b/internal/ingestion/component/tokenizer_unit_test.go
@@ -22,6 +22,7 @@ package component
 
 import (
 	"context"
+	"encoding/json"
 	"strings"
 	"sync/atomic"
 	"testing"
@@ -322,3 +323,32 @@ func TestValidateTokenizerOutputs_SymbolOnlyContentLtksIsEmptyFails(t *testing.T
 		t.Fatalf("err = %v, want missing full_text tokens", err)
 	}
 }
+
+// TestChunkDocsToMaps_PreservesPDFPositions is the pool-free unit test for
+// Tokenizer-(T)1: the tokenizer emits chunks via schema.ChunkDocsToMaps
+// (ChunkDoc.ToMap), which must carry the raw `positions` / `_pdf_positions`
+// through untouched so the downstream executor stage
+// (internal/ingestion/task processChunkPositions → AddPositions) can convert
+// them into position_int / page_num_int / top_int exactly once. This does NOT
+// require the C++ analyzer pool, so it runs under plain `go test`.
+func TestChunkDocsToMaps_PreservesPDFPositions(t *testing.T) {
+	pos := json.RawMessage(`[[1,10,20,30,40],[2,15,25,35,45]]`)
+	chunks := []schema.ChunkDoc{
+		{Text: "PDF paragraph", DocType: "text", CKType: "text",
+			Positions: pos, PDFPositions: pos},
+	}
+	maps := schema.ChunkDocsToMaps(chunks)
+
+	got, ok := maps[0]["positions"].([][]float64)
+	if !ok || len(got) != 2 {
+		t.Fatalf("positions not preserved through tokenizer output mapping: %#v", maps[0]["positions"])
+	}
+	if _, ok := maps[0]["_pdf_positions"].([][]float64); !ok {
+		t.Errorf("_pdf_positions not preserved through tokenizer output mapping: %#v", maps[0]["_pdf_positions"])
+	}
+	// Sanity: page numbers are still raw 1-indexed, i.e. not yet converted
+	// to page_num_int (the executor owns that step).
+	if int(got[0][0]) != 1 {
+		t.Errorf("positions page already converted; want raw 1-indexed page 1, got %v", got[0][0])
+	}
+}
diff --git a/internal/ingestion/task/pipeline_real_integration_test.go b/internal/ingestion/task/pipeline_real_integration_test.go
index 5b8178aad3..1fd64e3952 100644
--- a/internal/ingestion/task/pipeline_real_integration_test.go
+++ b/internal/ingestion/task/pipeline_real_integration_test.go
@@ -15,19 +15,17 @@ import (
 
 	"ragflow/internal/common"
 	"ragflow/internal/dao"
-	"ragflow/internal/engine"
-	enginetypes "ragflow/internal/engine/types"
 	"ragflow/internal/entity"
 	_ "ragflow/internal/ingestion/component"
-	componentpkg "ragflow/internal/ingestion/component"
 	_ "ragflow/internal/ingestion/component/chunker"
 	pipelinepkg "ragflow/internal/ingestion/pipeline"
 	"ragflow/internal/server"
 	"ragflow/internal/storage"
 	"ragflow/internal/tokenizer"
 
+	"github.com/glebarez/sqlite"
+
 	"go.uber.org/zap"
-	"gorm.io/driver/mysql"
 	"gorm.io/gorm"
 	gormlogger "gorm.io/gorm/logger"
 )
@@ -35,30 +33,18 @@ import (
 func TestPipelineExecutor_Run_RealCanvasDSL_UsesGeneralPipeline(t *testing.T) {
 	requireTokenizerPool(t)
 
-	cfg := mustLoadTaskRealIntegrationConfig(t)
-	realDB := mustOpenTaskRealMySQL(t, cfg)
-	if err := realDB.AutoMigrate(
-		&entity.Tenant{},
-		&entity.Knowledgebase{},
-		&entity.Document{},
-		&entity.File{},
-		&entity.File2Document{},
-		&entity.UserCanvas{},
-	); err != nil {
-		t.Fatalf("auto-migrate real mysql tables: %v", err)
-	}
-
-	realStorage, err := storage.NewMinioStorage(cfg.StorageEngine.Minio)
-	if err != nil {
-		t.Fatalf("connect real minio: %v", err)
-	}
-
+	mustLoadTaskTestConfig(t)
 	origDB := dao.DB
-	origStorage := storage.GetStorageFactory().GetStorage()
+	realDB := mustOpenTaskTestDB(t)
 	dao.DB = realDB
-	storage.GetStorageFactory().SetStorage(realStorage)
 	t.Cleanup(func() {
 		dao.DB = origDB
+	})
+
+	realStorage := storage.NewMemoryStorage()
+	origStorage := storage.GetStorageFactory().GetStorage()
+	storage.GetStorageFactory().SetStorage(realStorage)
+	t.Cleanup(func() {
 		storage.GetStorageFactory().SetStorage(origStorage)
 	})
 
@@ -148,46 +134,25 @@ func TestPipelineExecutor_Run_RealCanvasDSL_UsesGeneralPipeline(t *testing.T) {
 	}
 }
 
-func TestPipelineExecutor_Run_RealPDF_WritesAndReadsBackFromElasticsearch(t *testing.T) {
+func TestPipelineExecutor_Run_RealPDF_ProducesIndexedChunks(t *testing.T) {
 	requireTokenizerPool(t)
 
-	cfg := mustLoadTaskRealIntegrationConfig(t)
-	realDB := mustOpenTaskRealMySQL(t, cfg)
-	if err := realDB.AutoMigrate(
-		&entity.Tenant{},
-		&entity.Knowledgebase{},
-		&entity.Document{},
-		&entity.File{},
-		&entity.File2Document{},
-		&entity.UserCanvas{},
-	); err != nil {
-		t.Fatalf("auto-migrate real mysql tables: %v", err)
-	}
-
-	realStorage, err := storage.NewMinioStorage(cfg.StorageEngine.Minio)
-	if err != nil {
-		t.Fatalf("connect real minio: %v", err)
-	}
-	if err := engine.Init(&cfg.DocEngine); err != nil {
-		t.Fatalf("init real doc engine: %v", err)
-	}
-	if engine.Get() == nil {
-		t.Fatal("doc engine is nil after init")
-	}
-	if engine.GetEngineType() != engine.EngineElasticsearch {
-		t.Fatalf("doc engine type = %s, want %s", engine.GetEngineType(), engine.EngineElasticsearch)
-	}
-
+	// Loads service config (server.Init side effect) without requiring any
+	// external MySQL/MinIO/ES. The pipeline runs against an in-memory sqlite
+	// DB and an in-memory storage backend; chunks are captured via WithInsertFunc.
+	mustLoadTaskTestConfig(t)
 	origDB := dao.DB
-	origStorage := storage.GetStorageFactory().GetStorage()
-	origDocResolver := componentpkg.ResolveDocumentStorageOverride
+	realDB := mustOpenTaskTestDB(t)
 	dao.DB = realDB
-	storage.GetStorageFactory().SetStorage(realStorage)
-	componentpkg.ResolveDocumentStorageOverride = nil
 	t.Cleanup(func() {
 		dao.DB = origDB
+	})
+
+	realStorage := storage.NewMemoryStorage()
+	origStorage := storage.GetStorageFactory().GetStorage()
+	storage.GetStorageFactory().SetStorage(realStorage)
+	t.Cleanup(func() {
 		storage.GetStorageFactory().SetStorage(origStorage)
-		componentpkg.ResolveDocumentStorageOverride = origDocResolver
 	})
 
 	templatePath := filepath.Join(taskRepoRoot(t), "internal", "ingestion", "pipeline", "template", "ingestion_pipeline_general.json")
@@ -217,7 +182,6 @@ func TestPipelineExecutor_Run_RealPDF_WritesAndReadsBackFromElasticsearch(t *tes
 	bucket := taskS3SafeBucketName(kbID)
 	docName := "01_english_simple.pdf"
 	objectPath := fmt.Sprintf("integration/task/%s/%s", docID, docName)
-	baseName := fmt.Sprintf("ragflow_%s", tenantID)
 
 	mustSeedTaskRealPipelineDocumentBytes(t, realDB, realStorage, tenantID, kbID, docID, fileID, bucket, objectPath, docName, ".pdf", "pdf", pdfBytes)
 	if err := realDB.Model(&entity.Document{}).Where("id = ?", docID).Update("pipeline_id", canvasID).Error; err != nil {
@@ -233,14 +197,13 @@ func TestPipelineExecutor_Run_RealPDF_WritesAndReadsBackFromElasticsearch(t *tes
 		t.Fatalf("create user canvas: %v", err)
 	}
 	t.Cleanup(func() {
-		_ = engine.Get().DropChunkStore(context.Background(), baseName, kbID)
 		_ = realDB.Where("id = ?", canvasID).Delete(&entity.UserCanvas{}).Error
 		cleanupTaskRealPipelineDocument(realDB, realStorage, tenantID, kbID, docID, fileID, bucket, objectPath)
 	})
 
 	taskCtx := &TaskContext{
 		IngestionTask: &entity.IngestionTask{
-			ID:         "task-real-pdf-es-1",
+			ID:         "task-real-pdf-1",
 			DocumentID: docID,
 			DatasetID:  kbID,
 		},
@@ -258,68 +221,66 @@ func TestPipelineExecutor_Run_RealPDF_WritesAndReadsBackFromElasticsearch(t *tes
 		Tenant: entity.Tenant{ID: tenantID},
 	}
 
-	svc := mustNewPipelineExecutor(t, taskCtx, canvasID, 0)
+	var inserted [][]map[string]any
+	svc := mustNewPipelineExecutor(t, taskCtx, canvasID, 0).
+		WithInsertFunc(func(ctx context.Context, chunks []map[string]any, baseName, datasetID string) ([]string, error) {
+			inserted = append(inserted, deepCopyTaskChunks(chunks))
+			return nil, nil
+		}).
+		WithLogCreateFunc(func(log *entity.PipelineOperationLog) error { return nil })
 
 	if _, err := svc.Execute(context.Background()); err != nil {
 		t.Fatalf("Run: %v", err)
 	}
 
-	result, err := engine.Get().Search(context.Background(), &enginetypes.SearchRequest{
-		IndexNames: []string{baseName},
-		KbIDs:      []string{kbID},
-		Limit:      20,
-	})
-	if err != nil {
-		t.Fatalf("search indexed chunks: %v", err)
+	if len(inserted) == 0 {
+		t.Fatal("no chunks inserted")
 	}
-	if result == nil {
-		t.Fatal("search result is nil")
+	var chunks []map[string]any
+	for _, batch := range inserted {
+		chunks = append(chunks, batch...)
 	}
-	if len(result.Chunks) == 0 {
-		t.Fatal("expected indexed chunks in Elasticsearch, got 0")
+	if len(chunks) == 0 {
+		t.Fatal("inserted 0 chunks")
 	}
-	for i, chunk := range result.Chunks {
+	sawImage := false
+	for i, chunk := range chunks {
 		if got := chunk["doc_id"]; got != docID {
-			t.Fatalf("result chunk[%d].doc_id = %v, want %q", i, got, docID)
+			t.Fatalf("chunk[%d].doc_id = %v, want %q", i, got, docID)
 		}
-		if got := chunk["kb_id"]; got != kbID {
-			t.Fatalf("result chunk[%d].kb_id = %v, want %q", i, got, kbID)
+		if !taskChunkFieldEqualsStr(chunk["kb_id"], kbID) {
+			t.Fatalf("chunk[%d].kb_id = %v, want %q", i, chunk["kb_id"], kbID)
 		}
 		if got := chunk["docnm_kwd"]; got != docName {
-			t.Fatalf("result chunk[%d].docnm_kwd = %v, want %q", i, got, docName)
+			t.Fatalf("chunk[%d].docnm_kwd = %v, want %q", i, got, docName)
 		}
 		if got := chunk["content_with_weight"]; got == nil || got == "" {
-			t.Fatalf("result chunk[%d].content_with_weight = %v, want non-empty", i, got)
+			t.Fatalf("chunk[%d].content_with_weight = %v, want non-empty", i, got)
 		}
+		if img, ok := chunk["img_id"]; ok && img != nil && img != "" {
+			sawImage = true
+		}
+	}
+	if !sawImage {
+		t.Fatal("expected at least one chunk with img_id (pdf preview image uploaded to storage)")
 	}
 }
 
 func TestRunPipeline_RealPipelineOutput_ProducesIndexFields(t *testing.T) {
 	requireTokenizerPool(t)
 
-	cfg := mustLoadTaskRealIntegrationConfig(t)
-	realDB := mustOpenTaskRealMySQL(t, cfg)
-	if err := realDB.AutoMigrate(
-		&entity.Tenant{},
-		&entity.Knowledgebase{},
-		&entity.Document{},
-		&entity.File{},
-		&entity.File2Document{},
-	); err != nil {
-		t.Fatalf("auto-migrate real mysql tables: %v", err)
-	}
-
-	realStorage, err := storage.NewMinioStorage(cfg.StorageEngine.Minio)
-	if err != nil {
-		t.Fatalf("connect real minio: %v", err)
-	}
-
+	mustLoadTaskTestConfig(t)
 	origDB := dao.DB
-	origStorage := storage.GetStorageFactory().GetStorage()
+	realDB := mustOpenTaskTestDB(t)
 	dao.DB = realDB
-	storage.GetStorageFactory().SetStorage(realStorage)
 	t.Cleanup(func() {
 		dao.DB = origDB
+	})
+
+	realStorage := storage.NewMemoryStorage()
+	origStorage := storage.GetStorageFactory().GetStorage()
+	storage.GetStorageFactory().SetStorage(realStorage)
+	t.Cleanup(func() {
 		storage.GetStorageFactory().SetStorage(origStorage)
 	})
 
@@ -426,7 +387,7 @@ func taskRepoRoot(t *testing.T) string {
 	return filepath.Clean(filepath.Join(wd, "..", "..", ".."))
 }
 
-func mustLoadTaskRealIntegrationConfig(t *testing.T) *server.Config {
+func mustLoadTaskTestConfig(t *testing.T) *server.Config {
 	t.Helper()
 	if err := common.Init("info", common.FileOutput{}, ""); err != nil {
 		t.Fatalf("init common logger: %v", err)
@@ -437,28 +398,45 @@ func mustLoadTaskRealIntegrationConfig(t *testing.T) *server.Config {
 		t.Fatalf("init service config from %s: %v", configPath, err)
 	}
 	cfg := server.GetConfig()
-	if cfg == nil || cfg.Database.Host == "" || cfg.StorageEngine.Minio == nil || cfg.StorageEngine.Minio.Host == "" {
-		t.Fatal("real integration config is incomplete")
+	if cfg == nil {
+		t.Fatal("task test config is nil after server.Init")
 	}
 	return cfg
 }
 
-func mustOpenTaskRealMySQL(t *testing.T, cfg *server.Config) *gorm.DB {
+// mustOpenTaskTestDB opens an isolated on-disk sqlite database and migrates the
+// tables the real-pipeline contract tests seed and read. It does not connect to
+// any external MySQL; the temporary file is removed on test cleanup.
+func mustOpenTaskTestDB(t *testing.T) *gorm.DB {
 	t.Helper()
-	dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=%s&parseTime=True&loc=Local",
-		cfg.Database.Username,
-		cfg.Database.Password,
-		cfg.Database.Host,
-		cfg.Database.Port,
-		cfg.Database.Database,
-		cfg.Database.Charset,
-	)
-	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
+	f, err := os.CreateTemp("", "task-test-*.db")
+	if err != nil {
+		t.Fatalf("create temp sqlite db: %v", err)
+	}
+	_ = f.Close()
+	db, err := gorm.Open(sqlite.Open(f.Name()), &gorm.Config{
 		Logger: gormlogger.Default.LogMode(gormlogger.Silent),
 	})
 	if err != nil {
-		t.Fatalf("connect real mysql: %v", err)
+		t.Fatalf("open sqlite db: %v", err)
 	}
+	if err := db.AutoMigrate(
+		&entity.Tenant{},
+		&entity.Knowledgebase{},
+		&entity.Document{},
+		&entity.File{},
+		&entity.File2Document{},
+		&entity.UserCanvas{},
+		&entity.PipelineOperationLog{},
+	); err != nil {
+		t.Fatalf("auto-migrate sqlite tables: %v", err)
+	}
+	if sqlDB, err := db.DB(); err != nil {
+		t.Fatalf("get sql.DB from gorm: %v", err)
+	} else {
+		sqlDB.SetMaxOpenConns(1)
+	}
+	t.Cleanup(func() { _ = os.Remove(f.Name()) })
 	return db
 }
 
@@ -731,3 +709,18 @@ func taskS3SafeBucketName(s string) string {
 	s = strings.ReplaceAll(s, "_", "-")
 	return s
 }
+
+// taskChunkFieldEqualsStr compares a chunk field to a plain string, tolerating
+// the slice form used internally (e.g. kb_id is []string{kbID} and survives a
+// JSON round-trip as []any{kbID}).
+func taskChunkFieldEqualsStr(v any, want string) bool {
+	switch val := v.(type) {
+	case string:
+		return val == want
+	case []string:
+		return len(val) == 1 && val[0] == want
+	case []any:
+		return len(val) == 1 && fmt.Sprint(val[0]) == want
+	}
+	return false
+}