fix(feishu): extract images from post (rich text) messages

When users send text+image together in Feishu, the message type is
"post" (rich text) instead of "image". The image download logic only
handled MsgTypeImage, so images embedded in post messages were silently
ignored — the agent received raw JSON instead of actual image content.

- Add extractPostImageKeys() to parse img tags from post content
- Add extractPostText() to extract plain text from post content
- Handle MsgTypePost in downloadInboundMedia to download embedded images
- Handle MsgTypePost in appendMediaTags to add [image: photo] tag

pkg/channels/feishu/common.go

@@ -62,6 +62,61 @@ func extractJSONStringField(content, field string) string {
 // Format: {"image_key": "img_xxx"}
 func extractImageKey(content string) string { return extractJSONStringField(content, "image_key") }
 
+// extractPostImageKeys extracts all image_key values from a Feishu post (rich text) message.
+// Post content format: {"title":"...","content":[[{"tag":"img","image_key":"..."},...],...]}.
+func extractPostImageKeys(rawContent string) []string {
+	var post struct {
+		Content [][]struct {
+			Tag      string `json:"tag"`
+			ImageKey string `json:"image_key"`
+		} `json:"content"`
+	}
+	if err := json.Unmarshal([]byte(rawContent), &post); err != nil {
+		return nil
+	}
+
+	var keys []string
+	for _, paragraph := range post.Content {
+		for _, elem := range paragraph {
+			if elem.Tag == "img" && elem.ImageKey != "" {
+				keys = append(keys, elem.ImageKey)
+			}
+		}
+	}
+	return keys
+}
+
+// extractPostText extracts plain text from a Feishu post (rich text) message.
+// Returns title and text elements joined by newlines. Falls back to rawContent on parse error.
+func extractPostText(rawContent string) string {
+	var post struct {
+		Title   string `json:"title"`
+		Content [][]struct {
+			Tag  string `json:"tag"`
+			Text string `json:"text"`
+		} `json:"content"`
+	}
+	if err := json.Unmarshal([]byte(rawContent), &post); err != nil {
+		return rawContent
+	}
+
+	var parts []string
+	if post.Title != "" {
+		parts = append(parts, post.Title)
+	}
+	for _, paragraph := range post.Content {
+		for _, elem := range paragraph {
+			if elem.Tag == "text" && elem.Text != "" {
+				parts = append(parts, elem.Text)
+			}
+		}
+	}
+	if len(parts) == 0 {
+		return ""
+	}
+	return strings.Join(parts, "\n")
+}
+
 // extractFileKey extracts the file_key from a Feishu file/audio message content JSON.
 // Format: {"file_key": "file_xxx", "file_name": "...", ...}
 func extractFileKey(content string) string { return extractJSONStringField(content, "file_key") }

pkg/channels/feishu/common_test.go

@@ -134,6 +134,93 @@ func TestExtractFileKey(t *testing.T) {
 	}
 }
 
+func TestExtractPostImageKeys(t *testing.T) {
+	tests := []struct {
+		name       string
+		rawContent string
+		want       []string
+	}{
+		{
+			name:       "text and image",
+			rawContent: `{"title":"","content":[[{"tag":"img","image_key":"img_v3_abc","width":100,"height":100}],[{"tag":"text","text":"hello","style":[]}]]}`,
+			want:       []string{"img_v3_abc"},
+		},
+		{
+			name:       "multiple images",
+			rawContent: `{"title":"","content":[[{"tag":"img","image_key":"img_1","width":100,"height":100},{"tag":"img","image_key":"img_2","width":100,"height":100}]]}`,
+			want:       []string{"img_1", "img_2"},
+		},
+		{
+			name:       "no images",
+			rawContent: `{"title":"","content":[[{"tag":"text","text":"hello","style":[]}]]}`,
+			want:       nil,
+		},
+		{
+			name:       "invalid JSON",
+			rawContent: `not json`,
+			want:       nil,
+		},
+		{
+			name:       "empty content",
+			rawContent: `{"title":"","content":[]}`,
+			want:       nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := extractPostImageKeys(tt.rawContent)
+			if len(got) != len(tt.want) {
+				t.Errorf("extractPostImageKeys() = %v, want %v", got, tt.want)
+				return
+			}
+			for i := range got {
+				if got[i] != tt.want[i] {
+					t.Errorf("extractPostImageKeys()[%d] = %q, want %q", i, got[i], tt.want[i])
+				}
+			}
+		})
+	}
+}
+
+func TestExtractPostText(t *testing.T) {
+	tests := []struct {
+		name       string
+		rawContent string
+		want       string
+	}{
+		{
+			name:       "text and image",
+			rawContent: `{"title":"","content":[[{"tag":"img","image_key":"img_v3_abc","width":100,"height":100}],[{"tag":"text","text":"图里有啥","style":[]}]]}`,
+			want:       "图里有啥",
+		},
+		{
+			name:       "with title",
+			rawContent: `{"title":"My Post","content":[[{"tag":"text","text":"body text","style":[]}]]}`,
+			want:       "My Post\nbody text",
+		},
+		{
+			name:       "only images returns empty",
+			rawContent: `{"title":"","content":[[{"tag":"img","image_key":"img_v3_abc","width":100,"height":100}]]}`,
+			want:       "",
+		},
+		{
+			name:       "invalid JSON returns raw",
+			rawContent: `not json`,
+			want:       "not json",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := extractPostText(tt.rawContent)
+			if got != tt.want {
+				t.Errorf("extractPostText(%q) = %q, want %q", tt.rawContent, got, tt.want)
+			}
+		})
+	}
+}
+
 func TestExtractFileName(t *testing.T) {
 	tests := []struct {
 		name    string

pkg/channels/feishu/feishu_64.go

@@ -504,8 +504,8 @@ func extractContent(messageType, rawContent string) string {
 		return rawContent
 
 	case larkim.MsgTypePost:
-		// Pass raw JSON to LLM — structured rich text is more informative than flattened plain text
-		return rawContent
+		// Extract plain text from post; images are handled separately via downloadInboundMedia.
+		return extractPostText(rawContent)
 
 	case larkim.MsgTypeImage:
 		// Image messages don't have text content
@@ -544,6 +544,14 @@ func (c *FeishuChannel) downloadInboundMedia(
 			refs = append(refs, ref)
 		}
 
+	case larkim.MsgTypePost:
+		for _, imageKey := range extractPostImageKeys(rawContent) {
+			ref := c.downloadResource(ctx, messageID, imageKey, "image", ".jpg", store, scope)
+			if ref != "" {
+				refs = append(refs, ref)
+			}
+		}
+
 	case larkim.MsgTypeFile, larkim.MsgTypeAudio, larkim.MsgTypeMedia:
 		fileKey := extractFileKey(rawContent)
 		if fileKey == "" {
@@ -670,7 +678,7 @@ func appendMediaTags(content, messageType string, mediaRefs []string) string {
 
 	var tag string
 	switch messageType {
-	case larkim.MsgTypeImage:
+	case larkim.MsgTypeImage, larkim.MsgTypePost:
 		tag = "[image: photo]"
 	case larkim.MsgTypeAudio:
 		tag = "[audio]"

pkg/channels/feishu/feishu_64_test.go

@@ -28,10 +28,22 @@ func TestExtractContent(t *testing.T) {
 			want:        "not json",
 		},
 		{
-			name:        "post message returns raw JSON",
+			name:        "post message extracts text",
 			messageType: "post",
-			rawContent:  `{"title": "test post"}`,
-			want:        `{"title": "test post"}`,
+			rawContent:  `{"title":"","content":[[{"tag":"img","image_key":"img_v3_xxx","width":100,"height":100}],[{"tag":"text","text":"图里有啥","style":[]}]]}`,
+			want:        "图里有啥",
+		},
+		{
+			name:        "post message with title",
+			messageType: "post",
+			rawContent:  `{"title":"test post","content":[[{"tag":"text","text":"hello","style":[]}]]}`,
+			want:        "test post\nhello",
+		},
+		{
+			name:        "post message only images returns empty",
+			messageType: "post",
+			rawContent:  `{"title":"","content":[[{"tag":"img","image_key":"img_v3_xxx","width":100,"height":100}]]}`,
+			want:        "",
 		},
 		{
 			name:        "image message returns empty",
@@ -144,6 +156,20 @@ func TestAppendMediaTags(t *testing.T) {
 			mediaRefs:   []string{"ref1"},
 			want:        "report.pdf [file]",
 		},
+		{
+			name:        "post with image refs",
+			content:     "图里有啥",
+			messageType: "post",
+			mediaRefs:   []string{"ref1"},
+			want:        "图里有啥 [image: photo]",
+		},
+		{
+			name:        "post empty content with image refs",
+			content:     "",
+			messageType: "post",
+			mediaRefs:   []string{"ref1"},
+			want:        "[image: photo]",
+		},
 		{
 			name:        "unknown type",
 			content:     "something",