diff --git a/cmd/hf/main.go b/cmd/hf/main.go
index 5175af5..281d8cb 100644
--- a/cmd/hf/main.go
+++ b/cmd/hf/main.go
@@ -216,6 +216,9 @@ func handleGroup(group help.Group, args []string) {
 	case "project":
 		handleProjectCommand(sub.Name, remaining)
 		return
+	case "knowledge-base":
+		handleKnowledgeBaseCommand(sub.Name, remaining)
+		return
 	case "milestone":
 		handleMilestoneCommand(sub.Name, remaining)
 		return
@@ -731,6 +734,83 @@ func handleProjectCommand(subCmd string, args []string) {
 	}
 }
 
+func handleKnowledgeBaseCommand(subCmd string, args []string) {
+	tokenFlag := ""
+	var filtered []string
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--token":
+			if i+1 < len(args) {
+				i++
+				tokenFlag = args[i]
+			}
+		default:
+			filtered = append(filtered, args[i])
+		}
+	}
+
+	needArg := func(usage string) {
+		if len(filtered) < 1 {
+			output.Error(usage)
+		}
+	}
+
+	switch subCmd {
+	case "list":
+		commands.RunKnowledgeBaseList(filtered, tokenFlag)
+	case "get":
+		needArg("usage: hf knowledge-base get <kb-code>")
+		commands.RunKnowledgeBaseGet(filtered[0], tokenFlag)
+	case "create":
+		commands.RunKnowledgeBaseCreate(filtered, tokenFlag)
+	case "update":
+		needArg("usage: hf knowledge-base update <kb-code> [--title ...] [--desc ...]")
+		commands.RunKnowledgeBaseUpdate(filtered[0], filtered[1:], tokenFlag)
+	case "delete":
+		needArg("usage: hf knowledge-base delete <kb-code>")
+		commands.RunKnowledgeBaseDelete(filtered[0], tokenFlag)
+	case "tree":
+		needArg("usage: hf knowledge-base tree <kb-code>")
+		commands.RunKnowledgeBaseTree(filtered[0], tokenFlag)
+	case "link":
+		needArg("usage: hf knowledge-base link <kb-code> --project <project-code>")
+		commands.RunKnowledgeBaseLink(filtered[0], filtered[1:], tokenFlag)
+	case "unlink":
+		needArg("usage: hf knowledge-base unlink <kb-code> --project <project-code>")
+		commands.RunKnowledgeBaseUnlink(filtered[0], filtered[1:], tokenFlag)
+	case "topics":
+		needArg("usage: hf knowledge-base topics <kb-code>")
+		commands.RunKnowledgeBaseTopics(filtered[0], tokenFlag)
+	case "add-topic":
+		needArg("usage: hf knowledge-base add-topic <kb-code> --topic <name> [--desc ...]")
+		commands.RunKnowledgeBaseAddTopic(filtered[0], filtered[1:], tokenFlag)
+	case "update-topic":
+		needArg("usage: hf knowledge-base update-topic <topic-id> [--topic ...] [--desc ...]")
+		commands.RunKnowledgeBaseUpdateTopic(filtered[0], filtered[1:], tokenFlag)
+	case "delete-topic":
+		needArg("usage: hf knowledge-base delete-topic <topic-id>")
+		commands.RunKnowledgeBaseDeleteTopic(filtered[0], tokenFlag)
+	case "add-category":
+		commands.RunKnowledgeBaseAddCategory(filtered, tokenFlag)
+	case "update-category":
+		needArg("usage: hf knowledge-base update-category <category-id> [--name ...] [--parent ...] [--desc ...]")
+		commands.RunKnowledgeBaseUpdateCategory(filtered[0], filtered[1:], tokenFlag)
+	case "delete-category":
+		needArg("usage: hf knowledge-base delete-category <category-id>")
+		commands.RunKnowledgeBaseDeleteCategory(filtered[0], tokenFlag)
+	case "add-fact":
+		commands.RunKnowledgeBaseAddFact(filtered, tokenFlag)
+	case "update-fact":
+		needArg("usage: hf knowledge-base update-fact <fact-id> [--fact ...] [--category ...]")
+		commands.RunKnowledgeBaseUpdateFact(filtered[0], filtered[1:], tokenFlag)
+	case "delete-fact":
+		needArg("usage: hf knowledge-base delete-fact <fact-id>")
+		commands.RunKnowledgeBaseDeleteFact(filtered[0], tokenFlag)
+	default:
+		output.Errorf("hf knowledge-base %s is not implemented yet", subCmd)
+	}
+}
+
 func handleMeetingCommand(subCmd string, args []string) {
 	tokenFlag := ""
 	var filtered []string
diff --git a/internal/commands/knowledge_base.go b/internal/commands/knowledge_base.go
new file mode 100644
index 0000000..418b884
--- /dev/null
+++ b/internal/commands/knowledge_base.go
@@ -0,0 +1,658 @@
+package commands
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"git.hangman-lab.top/zhi/HarborForge.Cli/internal/client"
+	"git.hangman-lab.top/zhi/HarborForge.Cli/internal/config"
+	"git.hangman-lab.top/zhi/HarborForge.Cli/internal/output"
+)
+
+// kbResponse matches the backend KnowledgeBaseResponse schema.
+type kbResponse struct {
+	ID                int     `json:"id"`
+	KnowledgeBaseCode string  `json:"knowledge_base_code"`
+	Title             string  `json:"title"`
+	Description       *string `json:"description"`
+	CreatedBy         int     `json:"created_by"`
+	CreatedAt         string  `json:"created_at"`
+	LastUpdatedAt     string  `json:"last_updated_at"`
+}
+
+type kbFactNode struct {
+	ID   int    `json:"id"`
+	Fact string `json:"fact"`
+}
+
+type kbCategoryNode struct {
+	ID         int              `json:"id"`
+	Name       string           `json:"name"`
+	Categories []kbCategoryNode `json:"categories"`
+	Facts      []kbFactNode     `json:"facts"`
+}
+
+type kbTopicNode struct {
+	ID         int              `json:"id"`
+	Topic      string           `json:"topic"`
+	Categories []kbCategoryNode `json:"categories"`
+	Facts      []kbFactNode     `json:"facts"`
+}
+
+type kbTree struct {
+	Title             string        `json:"title"`
+	KnowledgeBaseCode string        `json:"knowledge_base_code"`
+	Topics            []kbTopicNode `json:"topics"`
+}
+
+func kbClient(tokenFlag string) *client.Client {
+	cfg, err := config.Load()
+	if err != nil {
+		output.Errorf("config error: %v", err)
+	}
+	return client.New(cfg.BaseURL, ResolveToken(tokenFlag))
+}
+
+func emitJSONOr(data []byte, fallback func()) {
+	if output.JSONMode {
+		var raw json.RawMessage
+		if err := json.Unmarshal(data, &raw); err != nil {
+			output.Errorf("invalid JSON response: %v", err)
+		}
+		output.PrintJSON(raw)
+		return
+	}
+	fallback()
+}
+
+// ---------------------------------------------------------------------------
+// Knowledge base CRUD
+// ---------------------------------------------------------------------------
+
+// RunKnowledgeBaseList implements `hf knowledge-base list [--project <project-code>]`.
+func RunKnowledgeBaseList(args []string, tokenFlag string) {
+	query := ""
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--project":
+			if i+1 >= len(args) {
+				output.Error("--project requires a value")
+			}
+			i++
+			query = appendQuery(query, "project", args[i])
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+
+	c := kbClient(tokenFlag)
+	path := "/knowledge-bases"
+	if query != "" {
+		path += "?" + query
+	}
+	data, err := c.Get(path)
+	if err != nil {
+		output.Errorf("failed to list knowledge bases: %v", err)
+	}
+
+	emitJSONOr(data, func() {
+		var kbs []kbResponse
+		if err := json.Unmarshal(data, &kbs); err != nil {
+			output.Errorf("cannot parse knowledge base list: %v", err)
+		}
+		headers := []string{"CODE", "TITLE", "DESCRIPTION"}
+		var rows [][]string
+		for _, k := range kbs {
+			desc := ""
+			if k.Description != nil {
+				desc = *k.Description
+				if len(desc) > 50 {
+					desc = desc[:47] + "..."
+				}
+			}
+			rows = append(rows, []string{k.KnowledgeBaseCode, k.Title, desc})
+		}
+		output.PrintTable(headers, rows)
+	})
+}
+
+// RunKnowledgeBaseGet implements `hf knowledge-base get <kb-code>`.
+func RunKnowledgeBaseGet(code, tokenFlag string) {
+	c := kbClient(tokenFlag)
+	data, err := c.Get("/knowledge-bases/" + code)
+	if err != nil {
+		output.Errorf("failed to get knowledge base: %v", err)
+	}
+	emitJSONOr(data, func() {
+		var k kbResponse
+		if err := json.Unmarshal(data, &k); err != nil {
+			output.Errorf("cannot parse knowledge base: %v", err)
+		}
+		desc := ""
+		if k.Description != nil {
+			desc = *k.Description
+		}
+		output.PrintKeyValue(
+			"code", k.KnowledgeBaseCode,
+			"title", k.Title,
+			"description", desc,
+			"created", k.CreatedAt,
+			"updated", k.LastUpdatedAt,
+		)
+	})
+}
+
+// RunKnowledgeBaseCreate implements `hf knowledge-base create --title <t> [--desc <d>]`.
+func RunKnowledgeBaseCreate(args []string, tokenFlag string) {
+	title, desc := "", ""
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--title":
+			if i+1 >= len(args) {
+				output.Error("--title requires a value")
+			}
+			i++
+			title = args[i]
+		case "--desc":
+			if i+1 >= len(args) {
+				output.Error("--desc requires a value")
+			}
+			i++
+			desc = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if title == "" {
+		output.Error("usage: hf knowledge-base create --title <title> [--desc <description>]")
+	}
+
+	payload := map[string]interface{}{"title": title}
+	if desc != "" {
+		payload["description"] = desc
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	data, err := c.Post("/knowledge-bases", bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to create knowledge base: %v", err)
+	}
+	emitJSONOr(data, func() {
+		var k kbResponse
+		if err := json.Unmarshal(data, &k); err != nil {
+			fmt.Printf("knowledge base created: %s\n", title)
+			return
+		}
+		fmt.Printf("knowledge base created: %s (code: %s)\n", k.Title, k.KnowledgeBaseCode)
+	})
+}
+
+// RunKnowledgeBaseUpdate implements `hf knowledge-base update <kb-code> [--title ...] [--desc ...]`.
+func RunKnowledgeBaseUpdate(code string, args []string, tokenFlag string) {
+	payload := make(map[string]interface{})
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--title":
+			if i+1 >= len(args) {
+				output.Error("--title requires a value")
+			}
+			i++
+			payload["title"] = args[i]
+		case "--desc":
+			if i+1 >= len(args) {
+				output.Error("--desc requires a value")
+			}
+			i++
+			payload["description"] = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if len(payload) == 0 {
+		output.Error("nothing to update — provide --title and/or --desc")
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	_, err := c.Patch("/knowledge-bases/"+code, bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to update knowledge base: %v", err)
+	}
+	fmt.Printf("knowledge base updated: %s\n", code)
+}
+
+// RunKnowledgeBaseDelete implements `hf knowledge-base delete <kb-code>`.
+func RunKnowledgeBaseDelete(code, tokenFlag string) {
+	c := kbClient(tokenFlag)
+	_, err := c.Delete("/knowledge-bases/" + code)
+	if err != nil {
+		output.Errorf("failed to delete knowledge base: %v", err)
+	}
+	fmt.Printf("knowledge base deleted: %s\n", code)
+}
+
+// RunKnowledgeBaseTree implements `hf knowledge-base tree <kb-code>`.
+func RunKnowledgeBaseTree(code, tokenFlag string) {
+	c := kbClient(tokenFlag)
+	data, err := c.Get("/knowledge-bases/" + code + "/tree")
+	if err != nil {
+		output.Errorf("failed to get knowledge base tree: %v", err)
+	}
+	emitJSONOr(data, func() {
+		var tree kbTree
+		if err := json.Unmarshal(data, &tree); err != nil {
+			output.Errorf("cannot parse tree: %v", err)
+		}
+		fmt.Printf("%s (%s)\n", tree.Title, tree.KnowledgeBaseCode)
+		for _, t := range tree.Topics {
+			fmt.Printf("  # %s [topic:%d]\n", t.Topic, t.ID)
+			for _, f := range t.Facts {
+				fmt.Printf("    - %s [fact:%d]\n", f.Fact, f.ID)
+			}
+			for _, cat := range t.Categories {
+				printKBCategory(cat, 2)
+			}
+		}
+	})
+}
+
+func printKBCategory(cat kbCategoryNode, depth int) {
+	indent := strings.Repeat("  ", depth)
+	fmt.Printf("%s> %s [category:%d]\n", indent, cat.Name, cat.ID)
+	for _, f := range cat.Facts {
+		fmt.Printf("%s  - %s [fact:%d]\n", indent, f.Fact, f.ID)
+	}
+	for _, child := range cat.Categories {
+		printKBCategory(child, depth+1)
+	}
+}
+
+// ---------------------------------------------------------------------------
+// Project links
+// ---------------------------------------------------------------------------
+
+// RunKnowledgeBaseLink implements `hf knowledge-base link <kb-code> --project <project-code>`.
+func RunKnowledgeBaseLink(code string, args []string, tokenFlag string) {
+	project := ""
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--project":
+			if i+1 >= len(args) {
+				output.Error("--project requires a value")
+			}
+			i++
+			project = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if project == "" {
+		output.Error("usage: hf knowledge-base link <kb-code> --project <project-code>")
+	}
+	body, _ := json.Marshal(map[string]interface{}{"knowledge_base": code})
+
+	c := kbClient(tokenFlag)
+	_, err := c.Post("/projects/"+project+"/knowledge-bases", bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to link knowledge base: %v", err)
+	}
+	fmt.Printf("knowledge base %s linked to project %s\n", code, project)
+}
+
+// RunKnowledgeBaseUnlink implements `hf knowledge-base unlink <kb-code> --project <project-code>`.
+func RunKnowledgeBaseUnlink(code string, args []string, tokenFlag string) {
+	project := ""
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--project":
+			if i+1 >= len(args) {
+				output.Error("--project requires a value")
+			}
+			i++
+			project = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if project == "" {
+		output.Error("usage: hf knowledge-base unlink <kb-code> --project <project-code>")
+	}
+
+	c := kbClient(tokenFlag)
+	_, err := c.Delete("/projects/" + project + "/knowledge-bases/" + code)
+	if err != nil {
+		output.Errorf("failed to unlink knowledge base: %v", err)
+	}
+	fmt.Printf("knowledge base %s unlinked from project %s\n", code, project)
+}
+
+// ---------------------------------------------------------------------------
+// Topics
+// ---------------------------------------------------------------------------
+
+// RunKnowledgeBaseTopics implements `hf knowledge-base topics <kb-code>`.
+func RunKnowledgeBaseTopics(code, tokenFlag string) {
+	c := kbClient(tokenFlag)
+	data, err := c.Get("/knowledge-bases/" + code + "/topics")
+	if err != nil {
+		output.Errorf("failed to list topics: %v", err)
+	}
+	emitJSONOr(data, func() {
+		var topics []struct {
+			ID          int     `json:"id"`
+			Topic       string  `json:"topic"`
+			Description *string `json:"description"`
+		}
+		if err := json.Unmarshal(data, &topics); err != nil {
+			output.Errorf("cannot parse topics: %v", err)
+		}
+		headers := []string{"ID", "TOPIC", "DESCRIPTION"}
+		var rows [][]string
+		for _, t := range topics {
+			desc := ""
+			if t.Description != nil {
+				desc = *t.Description
+			}
+			rows = append(rows, []string{fmt.Sprintf("%d", t.ID), t.Topic, desc})
+		}
+		output.PrintTable(headers, rows)
+	})
+}
+
+// RunKnowledgeBaseAddTopic implements `hf knowledge-base add-topic <kb-code> --topic <name> [--desc ...]`.
+func RunKnowledgeBaseAddTopic(code string, args []string, tokenFlag string) {
+	topic, desc := "", ""
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--topic":
+			if i+1 >= len(args) {
+				output.Error("--topic requires a value")
+			}
+			i++
+			topic = args[i]
+		case "--desc":
+			if i+1 >= len(args) {
+				output.Error("--desc requires a value")
+			}
+			i++
+			desc = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if topic == "" {
+		output.Error("usage: hf knowledge-base add-topic <kb-code> --topic <name> [--desc <description>]")
+	}
+	payload := map[string]interface{}{"topic": topic}
+	if desc != "" {
+		payload["description"] = desc
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	data, err := c.Post("/knowledge-bases/"+code+"/topics", bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to add topic: %v", err)
+	}
+	emitJSONOr(data, func() { fmt.Printf("topic added: %s\n", topic) })
+}
+
+// RunKnowledgeBaseUpdateTopic implements `hf knowledge-base update-topic <topic-id> [--topic ...] [--desc ...]`.
+func RunKnowledgeBaseUpdateTopic(topicID string, args []string, tokenFlag string) {
+	payload := make(map[string]interface{})
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--topic":
+			if i+1 >= len(args) {
+				output.Error("--topic requires a value")
+			}
+			i++
+			payload["topic"] = args[i]
+		case "--desc":
+			if i+1 >= len(args) {
+				output.Error("--desc requires a value")
+			}
+			i++
+			payload["description"] = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if len(payload) == 0 {
+		output.Error("nothing to update — provide --topic and/or --desc")
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	_, err := c.Patch("/knowledge-topics/"+topicID, bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to update topic: %v", err)
+	}
+	fmt.Printf("topic updated: %s\n", topicID)
+}
+
+// RunKnowledgeBaseDeleteTopic implements `hf knowledge-base delete-topic <topic-id>`.
+func RunKnowledgeBaseDeleteTopic(topicID, tokenFlag string) {
+	c := kbClient(tokenFlag)
+	_, err := c.Delete("/knowledge-topics/" + topicID)
+	if err != nil {
+		output.Errorf("failed to delete topic: %v", err)
+	}
+	fmt.Printf("topic deleted: %s\n", topicID)
+}
+
+// ---------------------------------------------------------------------------
+// Categories
+// ---------------------------------------------------------------------------
+
+// RunKnowledgeBaseAddCategory implements
+// `hf knowledge-base add-category --topic <id> --name <n> [--parent <id>] [--desc ...]`.
+func RunKnowledgeBaseAddCategory(args []string, tokenFlag string) {
+	name, desc := "", ""
+	var topicID, parentID *int
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--topic":
+			if i+1 >= len(args) {
+				output.Error("--topic requires a value")
+			}
+			i++
+			topicID = parseIntFlag("--topic", args[i])
+		case "--parent":
+			if i+1 >= len(args) {
+				output.Error("--parent requires a value")
+			}
+			i++
+			parentID = parseIntFlag("--parent", args[i])
+		case "--name":
+			if i+1 >= len(args) {
+				output.Error("--name requires a value")
+			}
+			i++
+			name = args[i]
+		case "--desc":
+			if i+1 >= len(args) {
+				output.Error("--desc requires a value")
+			}
+			i++
+			desc = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if topicID == nil || name == "" {
+		output.Error("usage: hf knowledge-base add-category --topic <topic-id> --name <name> [--parent <category-id>] [--desc <description>]")
+	}
+	payload := map[string]interface{}{"topic_id": *topicID, "name": name}
+	if parentID != nil {
+		payload["parent"] = *parentID
+	}
+	if desc != "" {
+		payload["description"] = desc
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	data, err := c.Post("/knowledge-categories", bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to add category: %v", err)
+	}
+	emitJSONOr(data, func() { fmt.Printf("category added: %s\n", name) })
+}
+
+// RunKnowledgeBaseUpdateCategory implements
+// `hf knowledge-base update-category <category-id> [--name ...] [--parent ...] [--desc ...]`.
+func RunKnowledgeBaseUpdateCategory(categoryID string, args []string, tokenFlag string) {
+	payload := make(map[string]interface{})
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--name":
+			if i+1 >= len(args) {
+				output.Error("--name requires a value")
+			}
+			i++
+			payload["name"] = args[i]
+		case "--parent":
+			if i+1 >= len(args) {
+				output.Error("--parent requires a value")
+			}
+			i++
+			payload["parent"] = *parseIntFlag("--parent", args[i])
+		case "--desc":
+			if i+1 >= len(args) {
+				output.Error("--desc requires a value")
+			}
+			i++
+			payload["description"] = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if len(payload) == 0 {
+		output.Error("nothing to update — provide --name, --parent and/or --desc")
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	_, err := c.Patch("/knowledge-categories/"+categoryID, bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to update category: %v", err)
+	}
+	fmt.Printf("category updated: %s\n", categoryID)
+}
+
+// RunKnowledgeBaseDeleteCategory implements `hf knowledge-base delete-category <category-id>`.
+func RunKnowledgeBaseDeleteCategory(categoryID, tokenFlag string) {
+	c := kbClient(tokenFlag)
+	_, err := c.Delete("/knowledge-categories/" + categoryID)
+	if err != nil {
+		output.Errorf("failed to delete category: %v", err)
+	}
+	fmt.Printf("category deleted: %s\n", categoryID)
+}
+
+// ---------------------------------------------------------------------------
+// Facts
+// ---------------------------------------------------------------------------
+
+// RunKnowledgeBaseAddFact implements
+// `hf knowledge-base add-fact --topic <id> [--category <id>] --fact <text>`.
+func RunKnowledgeBaseAddFact(args []string, tokenFlag string) {
+	factText := ""
+	var topicID, categoryID *int
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--topic":
+			if i+1 >= len(args) {
+				output.Error("--topic requires a value")
+			}
+			i++
+			topicID = parseIntFlag("--topic", args[i])
+		case "--category":
+			if i+1 >= len(args) {
+				output.Error("--category requires a value")
+			}
+			i++
+			categoryID = parseIntFlag("--category", args[i])
+		case "--fact":
+			if i+1 >= len(args) {
+				output.Error("--fact requires a value")
+			}
+			i++
+			factText = args[i]
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if topicID == nil || factText == "" {
+		output.Error("usage: hf knowledge-base add-fact --topic <topic-id> [--category <category-id>] --fact <text>")
+	}
+	payload := map[string]interface{}{"topic_id": *topicID, "fact": factText}
+	if categoryID != nil {
+		payload["category_id"] = *categoryID
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	data, err := c.Post("/knowledge-facts", bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to add fact: %v", err)
+	}
+	emitJSONOr(data, func() { fmt.Println("fact added") })
+}
+
+// RunKnowledgeBaseUpdateFact implements
+// `hf knowledge-base update-fact <fact-id> [--fact ...] [--category ...]`.
+func RunKnowledgeBaseUpdateFact(factID string, args []string, tokenFlag string) {
+	payload := make(map[string]interface{})
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--fact":
+			if i+1 >= len(args) {
+				output.Error("--fact requires a value")
+			}
+			i++
+			payload["fact"] = args[i]
+		case "--category":
+			if i+1 >= len(args) {
+				output.Error("--category requires a value")
+			}
+			i++
+			payload["category_id"] = *parseIntFlag("--category", args[i])
+		default:
+			output.Errorf("unknown flag: %s", args[i])
+		}
+	}
+	if len(payload) == 0 {
+		output.Error("nothing to update — provide --fact and/or --category")
+	}
+	body, _ := json.Marshal(payload)
+
+	c := kbClient(tokenFlag)
+	_, err := c.Patch("/knowledge-facts/"+factID, bytes.NewReader(body))
+	if err != nil {
+		output.Errorf("failed to update fact: %v", err)
+	}
+	fmt.Printf("fact updated: %s\n", factID)
+}
+
+// RunKnowledgeBaseDeleteFact implements `hf knowledge-base delete-fact <fact-id>`.
+func RunKnowledgeBaseDeleteFact(factID, tokenFlag string) {
+	c := kbClient(tokenFlag)
+	_, err := c.Delete("/knowledge-facts/" + factID)
+	if err != nil {
+		output.Errorf("failed to delete fact: %v", err)
+	}
+	fmt.Printf("fact deleted: %s\n", factID)
+}
+
+func parseIntFlag(flag, value string) *int {
+	var n int
+	if _, err := fmt.Sscanf(value, "%d", &n); err != nil {
+		output.Errorf("%s requires an integer value, got %q", flag, value)
+	}
+	return &n
+}
diff --git a/internal/help/surface.go b/internal/help/surface.go
index a2ce8c2..f49c299 100644
--- a/internal/help/surface.go
+++ b/internal/help/surface.go
@@ -84,6 +84,30 @@ func CommandSurface() []Group {
 				{Name: "remove-member", Description: "Remove a project member", Permitted: has(perms, "project.manage_members")},
 			},
 		},
+		{
+			Name:        "knowledge-base",
+			Description: "Manage knowledge bases (topics, categories, facts) and project links",
+			SubCommands: []Command{
+				{Name: "list", Description: "List knowledge bases", Permitted: has(perms, "knowledge-base.read")},
+				{Name: "get", Description: "Show a knowledge base by code", Permitted: has(perms, "knowledge-base.read")},
+				{Name: "tree", Description: "Show the full topic/category/fact tree", Permitted: has(perms, "knowledge-base.read")},
+				{Name: "topics", Description: "List topics in a knowledge base", Permitted: has(perms, "knowledge-base.read")},
+				{Name: "create", Description: "Create a knowledge base", Permitted: has(perms, "knowledge-base.create")},
+				{Name: "update", Description: "Update a knowledge base", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "delete", Description: "Delete a knowledge base", Permitted: has(perms, "knowledge-base.delete")},
+				{Name: "link", Description: "Link a knowledge base to a project", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "unlink", Description: "Unlink a knowledge base from a project", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "add-topic", Description: "Add a topic", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "update-topic", Description: "Update a topic", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "delete-topic", Description: "Delete a topic", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "add-category", Description: "Add a category", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "update-category", Description: "Update a category", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "delete-category", Description: "Delete a category (and its descendants)", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "add-fact", Description: "Add a fact", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "update-fact", Description: "Update a fact", Permitted: has(perms, "knowledge-base.update")},
+				{Name: "delete-fact", Description: "Delete a fact", Permitted: has(perms, "knowledge-base.update")},
+			},
+		},
 		{
 			Name:        "milestone",
 			Description: "Manage milestones",