feat(feishu): split messages with >5 tables to avoid API limit

- Add countMarkdownTables() to count markdown tables in content
- Add splitContentByTableCount() to split content when table count exceeds 5
- Update FeishuChannel.Send() to automatically split and send messages in parts
- Add comprehensive unit tests for table counting and splitting logic

Fixes API error when sending markdown messages with more than 5 tables
per Feishu message limit.

pkg/channels/feishu/common.go

@@ -8,9 +8,36 @@ import (
 	larkim "github.com/larksuite/oapi-sdk-go/v3/service/im/v1"
 )
 
+// maxTablesPerMessage is the maximum number of tables allowed per message
+const maxTablesPerMessage = 5
+
 // mentionPlaceholderRegex matches @_user_N placeholders inserted by Feishu for mentions.
 var mentionPlaceholderRegex = regexp.MustCompile(`@_user_\d+`)
 
+// isTableSeparator checks if a line is a markdown table separator row (|---|---| etc.)
+func isTableSeparator(line string) bool {
+	trimmed := strings.TrimSpace(line)
+	if trimmed == "" || !strings.HasPrefix(trimmed, "|") || !strings.HasSuffix(trimmed, "|") {
+		return false
+	}
+	// Remove leading and trailing |
+	trimmed = strings.Trim(trimmed, "|")
+
+	// Check if all remaining characters are -, |, : or space
+	hasDash := false
+	for _, c := range trimmed {
+		if c != '-' && c != '|' && c != ' ' && c != ':' {
+			return false
+		}
+		if c == '-' {
+			hasDash = true
+		}
+	}
+
+	// A separator must have at least one dash character
+	return hasDash
+}
+
 // stringValue safely dereferences a *string pointer.
 func stringValue(v *string) string {
 	if v == nil {
@@ -69,6 +96,52 @@ func extractFileKey(content string) string { return extractJSONStringField(conte
 // extractFileName extracts the file_name from a Feishu file message content JSON.
 func extractFileName(content string) string { return extractJSONStringField(content, "file_name") }
 
+// splitContentByTableCount splits the content into multiple parts if it contains too many tables.
+// Each part will have at most maxTablesPerMessage tables.
+func splitContentByTableCount(content string) []string {
+	var parts []string
+	lines := strings.Split(content, "\n")
+
+	var currentPart strings.Builder
+	var currentTableCount int
+	var inTable bool
+
+	for i, line := range lines {
+		trimmed := strings.TrimSpace(line)
+
+		// Check if this line starts with | and is not a separator
+		if strings.HasPrefix(trimmed, "|") && !isTableSeparator(trimmed) {
+			// Check if next line is a separator to confirm it's a table header
+			isTableHeader := i+1 < len(lines) && isTableSeparator(strings.TrimSpace(lines[i+1]))
+
+			if isTableHeader {
+				// Starting a new table (inTable may already be true for consecutive tables)
+				inTable = true
+				// Check if we need to start a new part
+				if currentTableCount >= maxTablesPerMessage && currentPart.Len() > 0 {
+					parts = append(parts, strings.TrimSpace(currentPart.String()))
+					currentPart.Reset()
+					currentTableCount = 0
+				}
+				currentTableCount++
+			}
+		} else if inTable && !strings.HasPrefix(trimmed, "|") {
+			// Non-table line ends a table
+			inTable = false
+		}
+
+		currentPart.WriteString(line)
+		currentPart.WriteString("\n")
+	}
+
+	// Add the last part
+	if currentPart.Len() > 0 {
+		parts = append(parts, strings.TrimSpace(currentPart.String()))
+	}
+
+	return parts
+}
+
 // stripMentionPlaceholders removes @_user_N placeholders from the text content.
 // These are inserted by Feishu when users @mention someone in a message.
 func stripMentionPlaceholders(content string, mentions []*larkim.MentionEvent) string {

pkg/channels/feishu/common_test.go

@@ -2,6 +2,8 @@ package feishu
 
 import (
 	"encoding/json"
+	"fmt"
+	"strings"
 	"testing"
 
 	larkim "github.com/larksuite/oapi-sdk-go/v3/service/im/v1"
@@ -290,3 +292,486 @@ func TestStripMentionPlaceholders(t *testing.T) {
 		})
 	}
 }
+
+func TestSplitContentByTableCount(t *testing.T) {
+	tests := []struct {
+		name      string
+		content   string
+		wantParts []string // Expected content of each part
+	}{
+		{
+			name:    "no tables - single part",
+			content: "Just some text without tables",
+			wantParts: []string{
+				"Just some text without tables",
+			},
+		},
+		{
+			name: "single table - single part",
+			content: `| Col1 | Col2 |
+|------|------|
+| Data | Data |`,
+			wantParts: []string{
+				`| Col1 | Col2 |
+|------|------|
+| Data | Data |`,
+			},
+		},
+		{
+			name:      "exactly 5 tables - single part",
+			content:   generateTableContent(1, 5),
+			wantParts: []string{generateTableContent(1, 5)},
+		},
+		{
+			name:      "6 tables - split into 2 parts",
+			content:   generateTableContent(1, 6),
+			wantParts: []string{generateTableContent(1, 5), generateTableContent(6, 6)},
+		},
+		{
+			name: "text before and between tables",
+			content: `Intro text
+
+| T1C1 | T1C2 |
+|------|------|
+| Data | Data |
+
+Middle text
+
+| T2C1 | T2C2 |
+|------|------|
+| Data | Data |
+
+| T3C1 | T3C2 |
+|------|------|
+| Data | Data |
+
+| T4C1 | T4C2 |
+|------|------|
+| Data | Data |
+
+| T5C1 | T5C2 |
+|------|------|
+| Data | Data |
+
+| T6C1 | T6C2 |
+|------|------|
+| Data | Data |
+
+Outro text`,
+			wantParts: []string{
+				`Intro text
+
+| T1C1 | T1C2 |
+|------|------|
+| Data | Data |
+
+Middle text
+
+| T2C1 | T2C2 |
+|------|------|
+| Data | Data |
+
+| T3C1 | T3C2 |
+|------|------|
+| Data | Data |
+
+| T4C1 | T4C2 |
+|------|------|
+| Data | Data |
+
+| T5C1 | T5C2 |
+|------|------|
+| Data | Data |`,
+				`| T6C1 | T6C2 |
+|------|------|
+| Data | Data |
+
+Outro text`,
+			},
+		},
+		{
+			name:    "10 tables - split into 2 parts",
+			content: generateTableContent(1, 10),
+			wantParts: []string{
+				generateTableContent(1, 5),
+				generateTableContent(6, 10),
+			},
+		},
+		{
+			name:    "11 tables - split into 3 parts",
+			content: generateTableContent(1, 11),
+			wantParts: []string{
+				generateTableContent(1, 5),
+				generateTableContent(6, 10),
+				generateTableContent(11, 11),
+			},
+		},
+		{
+			name: "6 tables - verify tables are not truncated at split boundary",
+			content: `| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |
+
+| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			wantParts: []string{
+				`| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |`,
+				`| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			},
+		},
+		{
+			name: "consecutive tables without blank line between them",
+			content: `| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |
+| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			wantParts: []string{
+				`| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |`,
+				`| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			},
+		},
+		{
+			name: "content ends with table (no trailing newline or blank line)",
+			content: `| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |
+
+| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			wantParts: []string{
+				`| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |`,
+				`| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			},
+		},
+		{
+			name: "table followed by text without blank line",
+			content: `| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+Some text immediately after table
+
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |
+
+| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			wantParts: []string{
+				`| T1C1 | T1C2 |
+|------|------|
+| D1 | D1 |
+Some text immediately after table
+
+| T2C1 | T2C2 |
+|------|------|
+| D2 | D2 |
+
+| T3C1 | T3C2 |
+|------|------|
+| D3 | D3 |
+
+| T4C1 | T4C2 |
+|------|------|
+| D4 | D4 |
+
+| T5C1 | T5C2 |
+|------|------|
+| D5 | D5 |`,
+				`| T6C1 | T6C2 |
+|------|------|
+| D6 | D6 |`,
+			},
+		},
+		{
+			name: "text before 6th table goes to part 1",
+			content: `| T1 | T2 |
+|----|----|
+| D1 | D1 |
+
+| T1 | T2 |
+|----|----|
+| D2 | D2 |
+
+| T1 | T2 |
+|----|----|
+| D3 | D3 |
+
+| T1 | T2 |
+|----|----|
+| D4 | D4 |
+
+| T1 | T2 |
+|----|----|
+| D5 | D5 |
+
+Intro text for table 6
+
+| T1 | T2 |
+|----|----|
+| D6 | D6 |`,
+			wantParts: []string{
+				`| T1 | T2 |
+|----|----|
+| D1 | D1 |
+
+| T1 | T2 |
+|----|----|
+| D2 | D2 |
+
+| T1 | T2 |
+|----|----|
+| D3 | D3 |
+
+| T1 | T2 |
+|----|----|
+| D4 | D4 |
+
+| T1 | T2 |
+|----|----|
+| D5 | D5 |
+
+Intro text for table 6`,
+				`| T1 | T2 |
+|----|----|
+| D6 | D6 |`,
+			},
+		},
+		{
+			name: "single row table (header only, no data rows)",
+			content: `| T1C1 | T1C2 |
+|------|------|
+
+| T2C1 | T2C2 |
+|------|------|
+
+| T3C1 | T3C2 |
+|------|------|
+
+| T4C1 | T4C2 |
+|------|------|
+
+| T5C1 | T5C2 |
+|------|------|
+
+| T6C1 | T6C2 |
+|------|------|`,
+			wantParts: []string{
+				`| T1C1 | T1C2 |
+|------|------|
+
+| T2C1 | T2C2 |
+|------|------|
+
+| T3C1 | T3C2 |
+|------|------|
+
+| T4C1 | T4C2 |
+|------|------|
+
+| T5C1 | T5C2 |
+|------|------|`,
+				`| T6C1 | T6C2 |
+|------|------|`,
+			},
+		},
+		{
+			name: "table with alignment colons in separator",
+			content: `| Left | Center | Right |
+|:-----|:------:|------:|
+| L1 | C1 | R1 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L2 | C2 | R2 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L3 | C3 | R3 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L4 | C4 | R4 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L5 | C5 | R5 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L6 | C6 | R6 |`,
+			wantParts: []string{
+				`| Left | Center | Right |
+|:-----|:------:|------:|
+| L1 | C1 | R1 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L2 | C2 | R2 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L3 | C3 | R3 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L4 | C4 | R4 |
+
+| Left | Center | Right |
+|:-----|:------:|------:|
+| L5 | C5 | R5 |`,
+				`| Left | Center | Right |
+|:-----|:------:|------:|
+| L6 | C6 | R6 |`,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := splitContentByTableCount(tt.content)
+
+			// Verify number of parts
+			if len(got) != len(tt.wantParts) {
+				t.Errorf("splitContentByTableCount() returned %d parts, want %d", len(got), len(tt.wantParts))
+			}
+
+			// Verify content matches exactly
+			for i, expected := range tt.wantParts {
+				if got[i] != expected {
+					t.Errorf("Part %d mismatch:\ngot:\n%q\nwant:\n%q", i+1, got[i], expected)
+				}
+			}
+		})
+	}
+}
+
+// Helper function to generate content with tables from start to end (inclusive)
+func generateTableContent(start, end int) string {
+	var sb strings.Builder
+	for i := start; i <= end; i++ {
+		sb.WriteString(fmt.Sprintf("| T%dC1 | T%dC2 |\n", i, i))
+		sb.WriteString("|------|------|\n")
+		sb.WriteString("| Data | Data |")
+		if i < end {
+			sb.WriteString("\n")
+		}
+	}
+	return sb.String()
+}

pkg/channels/feishu/feishu_64.go

@@ -12,6 +12,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"sync/atomic"
 
@@ -113,6 +114,7 @@ func (c *FeishuChannel) Stop(ctx context.Context) error {
 }
 
 // Send sends a message using Interactive Card format for markdown rendering.
+// If the content contains more than 5 tables, it will be split into multiple messages.
 func (c *FeishuChannel) Send(ctx context.Context, msg bus.OutboundMessage) error {
 	if !c.IsRunning() {
 		return channels.ErrNotRunning
@@ -122,34 +124,86 @@ func (c *FeishuChannel) Send(ctx context.Context, msg bus.OutboundMessage) error
 		return fmt.Errorf("chat ID is empty: %w", channels.ErrSendFailed)
 	}
 
-	// Build interactive card with markdown content
+	// Split content into multiple parts if it contains too many tables
-	cardContent, err := buildMarkdownCard(msg.Content)
+	parts := splitContentByTableCount(msg.Content)
-	if err != nil {
+
-		return fmt.Errorf("feishu send: card build failed: %w", err)
+	// Send each part as a separate message
+	for i, part := range parts {
+		if strings.TrimSpace(part) == "" {
+			continue
+		}
+
+		// Build interactive card with markdown content
+		cardContent, err := buildMarkdownCard(part)
+		if err != nil {
+			return fmt.Errorf("feishu send: card build failed (part %d/%d): %w", i+1, len(parts), err)
+		}
+
+		if err := c.sendCard(ctx, msg.ChatID, cardContent); err != nil {
+			return fmt.Errorf("feishu send: failed to send part %d/%d: %w", i+1, len(parts), err)
+		}
+
+		logger.DebugCF("feishu", "Feishu message part sent", map[string]any{
+			"chat_id": msg.ChatID,
+			"part":    i + 1,
+			"total":   len(parts),
+		})
 	}
-	return c.sendCard(ctx, msg.ChatID, cardContent)
+
+	return nil
 }
 
 // EditMessage implements channels.MessageEditor.
 // Uses Message.Patch to update an interactive card message.
+// If the content contains more than 5 tables, it will be split:
+// the first part edits the original message, and remaining parts are sent as new messages.
 func (c *FeishuChannel) EditMessage(ctx context.Context, chatID, messageID, content string) error {
-	cardContent, err := buildMarkdownCard(content)
+	// Split content into multiple parts if it contains too many tables
-	if err != nil {
+	parts := splitContentByTableCount(content)
-		return fmt.Errorf("feishu edit: card build failed: %w", err)
+
+	// Edit the original message with the first part
+	if len(parts) > 0 && strings.TrimSpace(parts[0]) != "" {
+		cardContent, err := buildMarkdownCard(parts[0])
+		if err != nil {
+			return fmt.Errorf("feishu edit: card build failed: %w", err)
+		}
+
+		req := larkim.NewPatchMessageReqBuilder().
+			MessageId(messageID).
+			Body(larkim.NewPatchMessageReqBodyBuilder().Content(cardContent).Build()).
+			Build()
+
+		resp, err := c.client.Im.V1.Message.Patch(ctx, req)
+		if err != nil {
+			return fmt.Errorf("feishu edit: %w", err)
+		}
+		if !resp.Success() {
+			return fmt.Errorf("feishu edit api error (code=%d msg=%s)", resp.Code, resp.Msg)
+		}
 	}
 
-	req := larkim.NewPatchMessageReqBuilder().
+	// Send remaining parts as new messages
-		MessageId(messageID).
+	for i := 1; i < len(parts); i++ {
-		Body(larkim.NewPatchMessageReqBodyBuilder().Content(cardContent).Build()).
+		if strings.TrimSpace(parts[i]) == "" {
-		Build()
+			continue
+		}
 
-	resp, err := c.client.Im.V1.Message.Patch(ctx, req)
+		cardContent, err := buildMarkdownCard(parts[i])
-	if err != nil {
+		if err != nil {
-		return fmt.Errorf("feishu edit: %w", err)
+			return fmt.Errorf("feishu edit: card build failed (part %d/%d): %w", i+1, len(parts), err)
-	}
+		}
-	if !resp.Success() {
+
-		return fmt.Errorf("feishu edit api error (code=%d msg=%s)", resp.Code, resp.Msg)
+		if err := c.sendCard(ctx, chatID, cardContent); err != nil {
+			return fmt.Errorf("feishu edit: failed to send part %d/%d: %w", i+1, len(parts), err)
+		}
+
+		logger.DebugCF("feishu", "Feishu edit: additional message part sent", map[string]any{
+			"chat_id": chatID,
+			"part":    i + 1,
+			"total":   len(parts),
+		})
 	}
+
 	return nil
 }