diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..232dce9
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+/bin/
+*.exe
+*.test
+*.out
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..223253c
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,16 @@
+BINARY      := task-master
+CMD         := ./cmd/task-master
+VERSION_PKG := task/internal/version
+GIT_HASH    := $(shell git rev-parse --short HEAD 2>/dev/null || echo unknown)
+LDFLAGS     := -X $(VERSION_PKG).BuildVersion=$(GIT_HASH)
+
+.PHONY: build run version
+
+build:
+	go build -ldflags "$(LDFLAGS)" -o bin/$(BINARY) $(CMD)
+
+run: build
+	./bin/$(BINARY)
+
+version: build
+	./bin/$(BINARY) version
diff --git a/cmd/task-master/main.go b/cmd/task-master/main.go
new file mode 100644
index 0000000..d05cbd8
--- /dev/null
+++ b/cmd/task-master/main.go
@@ -0,0 +1,69 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	tea "github.com/charmbracelet/bubbletea"
+
+	"task/internal/command"
+	"task/internal/config"
+	"task/internal/project"
+	"task/internal/ticket"
+	"task/internal/ui"
+	"task/internal/version"
+)
+
+func main() {
+	if len(os.Args) > 1 {
+		switch os.Args[1] {
+		case "version", "--version", "-v":
+			fmt.Printf("%s  %s\n", config.AppName, version.BuildVersion)
+			return
+		case "help", "--help", "-h":
+			printHelp()
+			return
+		default:
+			fmt.Fprintf(os.Stderr, "unknown command: %s\n", os.Args[1])
+			printHelp()
+			os.Exit(1)
+		}
+	}
+
+	if err := run(); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	cfg, err := config.LoadOrCreate()
+	if err != nil {
+		return fmt.Errorf("config: %w", err)
+	}
+
+	store := ticket.NewJSONStore(cfg.DataDir)
+	projects := project.NewDirStore(cfg.DataDir)
+	if err := projects.Ensure(cfg.ActiveProject); err != nil {
+		return fmt.Errorf("ensure project: %w", err)
+	}
+
+	history := command.NewHistory()
+	model := ui.New(cfg, store, projects, history)
+	prog := tea.NewProgram(model, tea.WithAltScreen())
+	if _, err := prog.Run(); err != nil {
+		return fmt.Errorf("tui: %w", err)
+	}
+	return nil
+}
+
+func printHelp() {
+	fmt.Printf(`%s — offline-first terminal task manager
+
+Usage:
+  %s           Start the TUI
+  %s version   Print build version
+  %s help      Show this help
+
+`, config.AppName, config.AppName, config.AppName, config.AppName)
+}
diff --git a/go.mod b/go.mod
index a335f9f..0f4b595 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,47 @@
 module task
 
 go 1.27.0
+
+require (
+	github.com/charmbracelet/bubbles v1.0.0
+	github.com/charmbracelet/bubbletea v1.3.10
+	github.com/charmbracelet/glamour v1.0.0
+	github.com/charmbracelet/lipgloss v1.1.1-0.20250404203927-76690c660834
+	github.com/google/uuid v1.6.0
+	github.com/muesli/termenv v0.16.0
+)
+
+require (
+	github.com/alecthomas/chroma/v2 v2.20.0 // indirect
+	github.com/atotto/clipboard v0.1.4 // indirect
+	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
+	github.com/aymerick/douceur v0.2.0 // indirect
+	github.com/charmbracelet/colorprofile v0.4.1 // indirect
+	github.com/charmbracelet/x/ansi v0.11.6 // indirect
+	github.com/charmbracelet/x/cellbuf v0.0.15 // indirect
+	github.com/charmbracelet/x/exp/slice v0.0.0-20250327172914-2fdc97757edf // indirect
+	github.com/charmbracelet/x/term v0.2.2 // indirect
+	github.com/clipperhouse/displaywidth v0.9.0 // indirect
+	github.com/clipperhouse/stringish v0.1.1 // indirect
+	github.com/clipperhouse/uax29/v2 v2.5.0 // indirect
+	github.com/dlclark/regexp2 v1.11.5 // indirect
+	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
+	github.com/gorilla/css v1.0.1 // indirect
+	github.com/lucasb-eyer/go-colorful v1.3.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-localereader v0.0.1 // indirect
+	github.com/mattn/go-runewidth v0.0.19 // indirect
+	github.com/microcosm-cc/bluemonday v1.0.27 // indirect
+	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
+	github.com/muesli/cancelreader v0.2.2 // indirect
+	github.com/muesli/reflow v0.3.0 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/sahilm/fuzzy v0.1.1 // indirect
+	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
+	github.com/yuin/goldmark v1.7.13 // indirect
+	github.com/yuin/goldmark-emoji v1.0.6 // indirect
+	golang.org/x/net v0.38.0 // indirect
+	golang.org/x/sys v0.38.0 // indirect
+	golang.org/x/term v0.36.0 // indirect
+	golang.org/x/text v0.30.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..5684a39
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,95 @@
+github.com/alecthomas/assert/v2 v2.11.0 h1:2Q9r3ki8+JYXvGsDyBXwH3LcJ+WK5D0gc5E8vS6K3D0=
+github.com/alecthomas/assert/v2 v2.11.0/go.mod h1:Bze95FyfUr7x34QZrjL+XP+0qgp/zg8yS+TtBj1WA3k=
+github.com/alecthomas/chroma/v2 v2.20.0 h1:sfIHpxPyR07/Oylvmcai3X/exDlE8+FA820NTz+9sGw=
+github.com/alecthomas/chroma/v2 v2.20.0/go.mod h1:e7tViK0xh/Nf4BYHl00ycY6rV7b8iXBksI9E359yNmA=
+github.com/alecthomas/repr v0.5.1 h1:E3G4t2QbHTSNpPKBgMTln5KLkZHLOcU7r37J4pXBuIg=
+github.com/alecthomas/repr v0.5.1/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
+github.com/atotto/clipboard v0.1.4 h1:EH0zSVneZPSuFR11BlR9YppQTVDbh5+16AmcJi4g1z4=
+github.com/atotto/clipboard v0.1.4/go.mod h1:ZY9tmq7sm5xIbd9bOK4onWV4S6X0u6GY7Vn0Yu86PYI=
+github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiErDT4WkJ2k=
+github.com/aymanbagabas/go-osc52/v2 v2.0.1/go.mod h1:uYgXzlJ7ZpABp8OJ+exZzJJhRNQ2ASbcXHWsFqH8hp8=
+github.com/aymanbagabas/go-udiff v0.3.1 h1:LV+qyBQ2pqe0u42ZsUEtPiCaUoqgA9gYRDs3vj1nolY=
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+github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuPk=
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+github.com/charmbracelet/bubbletea v1.3.10 h1:otUDHWMMzQSB0Pkc87rm691KZ3SWa4KUlvF9nRvCICw=
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+github.com/charmbracelet/colorprofile v0.4.1 h1:a1lO03qTrSIRaK8c3JRxJDZOvhvIeSco3ej+ngLk1kk=
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+github.com/charmbracelet/glamour v1.0.0 h1:AWMLOVFHTsysl4WV8T8QgkQ0s/ZNZo7CiE4WKhk8l08=
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+golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/term v0.36.0 h1:zMPR+aF8gfksFprF/Nc/rd1wRS1EI6nDBGyWAvDzx2Q=
+golang.org/x/term v0.36.0/go.mod h1:Qu394IJq6V6dCBRgwqshf3mPF85AqzYEzofzRdZkWss=
+golang.org/x/text v0.30.0 h1:yznKA/E9zq54KzlzBEAWn1NXSQ8DIp/NYMy88xJjl4k=
+golang.org/x/text v0.30.0/go.mod h1:yDdHFIX9t+tORqspjENWgzaCVXgk0yYnYuSZ8UzzBVM=
diff --git a/internal/command/command.go b/internal/command/command.go
new file mode 100644
index 0000000..c50d476
--- /dev/null
+++ b/internal/command/command.go
@@ -0,0 +1,10 @@
+package command
+
+import "context"
+
+// Command is a reversible unit of work for future offline sync / undo trees.
+type Command interface {
+	Execute(ctx context.Context) error
+	Undo(ctx context.Context) error
+	Name() string
+}
diff --git a/internal/command/executor.go b/internal/command/executor.go
new file mode 100644
index 0000000..96d6d34
--- /dev/null
+++ b/internal/command/executor.go
@@ -0,0 +1,124 @@
+package command
+
+import (
+	"context"
+	"fmt"
+	"sync"
+)
+
+// Executor runs commands and supports undo/redo of successful ones.
+type Executor interface {
+	Do(cmd Command) error
+	Undo() error
+	Redo() error
+	CanUndo() bool
+	CanRedo() bool
+	LastUndoName() string
+	LastRedoName() string
+}
+
+// History is an in-memory undo/redo stack for Command values.
+type History struct {
+	mu    sync.Mutex
+	undoS []Command
+	redoS []Command
+}
+
+// NewHistory creates an empty command history.
+func NewHistory() *History {
+	return &History{}
+}
+
+// Do executes cmd and pushes it onto the undo stack. The redo stack is cleared.
+func (h *History) Do(cmd Command) error {
+	if err := cmd.Execute(context.Background()); err != nil {
+		return err
+	}
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	h.undoS = append(h.undoS, cmd)
+	h.redoS = nil
+	return nil
+}
+
+// Undo reverses the last successful command.
+func (h *History) Undo() error {
+	h.mu.Lock()
+	if len(h.undoS) == 0 {
+		h.mu.Unlock()
+		return fmt.Errorf("nothing to undo")
+	}
+	cmd := h.undoS[len(h.undoS)-1]
+	h.undoS = h.undoS[:len(h.undoS)-1]
+	h.mu.Unlock()
+
+	if err := cmd.Undo(context.Background()); err != nil {
+		h.mu.Lock()
+		h.undoS = append(h.undoS, cmd)
+		h.mu.Unlock()
+		return err
+	}
+
+	h.mu.Lock()
+	h.redoS = append(h.redoS, cmd)
+	h.mu.Unlock()
+	return nil
+}
+
+// Redo re-applies the last undone command.
+func (h *History) Redo() error {
+	h.mu.Lock()
+	if len(h.redoS) == 0 {
+		h.mu.Unlock()
+		return fmt.Errorf("nothing to redo")
+	}
+	cmd := h.redoS[len(h.redoS)-1]
+	h.redoS = h.redoS[:len(h.redoS)-1]
+	h.mu.Unlock()
+
+	if err := cmd.Execute(context.Background()); err != nil {
+		h.mu.Lock()
+		h.redoS = append(h.redoS, cmd)
+		h.mu.Unlock()
+		return err
+	}
+
+	h.mu.Lock()
+	h.undoS = append(h.undoS, cmd)
+	h.mu.Unlock()
+	return nil
+}
+
+// CanUndo reports whether Undo would succeed.
+func (h *History) CanUndo() bool {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return len(h.undoS) > 0
+}
+
+// CanRedo reports whether Redo would succeed.
+func (h *History) CanRedo() bool {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return len(h.redoS) > 0
+}
+
+// LastUndoName returns the name of the next undo command, or "".
+func (h *History) LastUndoName() string {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if len(h.undoS) == 0 {
+		return ""
+	}
+	return h.undoS[len(h.undoS)-1].Name()
+}
+
+// LastRedoName returns the name of the next redo command, or "".
+func (h *History) LastRedoName() string {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if len(h.redoS) == 0 {
+		return ""
+	}
+	return h.redoS[len(h.redoS)-1].Name()
+}
diff --git a/internal/command/history_test.go b/internal/command/history_test.go
new file mode 100644
index 0000000..4da7034
--- /dev/null
+++ b/internal/command/history_test.go
@@ -0,0 +1,90 @@
+package command_test
+
+import (
+	"testing"
+
+	"task/internal/command"
+	"task/internal/ticket"
+)
+
+func TestHistoryUndoRedoCreateDelete(t *testing.T) {
+	store := ticket.NewJSONStore(t.TempDir())
+	h := command.NewHistory()
+
+	create := &command.CreateTicket{
+		Store: store,
+		Ticket: ticket.Ticket{
+			Title:     "A",
+			ProjectID: "inbox",
+			Status:    ticket.StatusTodo,
+		},
+	}
+	if err := h.Do(create); err != nil {
+		t.Fatal(err)
+	}
+	list, err := store.List("inbox")
+	if err != nil || len(list) != 1 {
+		t.Fatalf("after create: %v len=%d", err, len(list))
+	}
+
+	if err := h.Undo(); err != nil {
+		t.Fatal(err)
+	}
+	list, err = store.List("inbox")
+	if err != nil || len(list) != 0 {
+		t.Fatalf("after undo create: %v len=%d", err, len(list))
+	}
+
+	if err := h.Redo(); err != nil {
+		t.Fatal(err)
+	}
+	list, err = store.List("inbox")
+	if err != nil || len(list) != 1 {
+		t.Fatalf("after redo create: %v len=%d", err, len(list))
+	}
+
+	del := &command.DeleteTicket{Store: store, Snapshot: list[0]}
+	if err := h.Do(del); err != nil {
+		t.Fatal(err)
+	}
+	list, _ = store.List("inbox")
+	if len(list) != 0 {
+		t.Fatal("expected empty after delete")
+	}
+	if err := h.Undo(); err != nil {
+		t.Fatal(err)
+	}
+	list, _ = store.List("inbox")
+	if len(list) != 1 {
+		t.Fatal("expected restored after undo delete")
+	}
+}
+
+func TestHistoryUpdateUndo(t *testing.T) {
+	store := ticket.NewJSONStore(t.TempDir())
+	created, err := store.Create(ticket.Ticket{
+		Title: "A", ProjectID: "inbox", Status: ticket.StatusTodo,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	after := created
+	after.Status = ticket.StatusDone
+	after.Title = "B"
+
+	h := command.NewHistory()
+	if err := h.Do(&command.UpdateTicket{Store: store, Before: created, After: after}); err != nil {
+		t.Fatal(err)
+	}
+	got, _ := store.Get(created.ID)
+	if got.Status != ticket.StatusDone || got.Title != "B" {
+		t.Fatalf("got %+v", got)
+	}
+	if err := h.Undo(); err != nil {
+		t.Fatal(err)
+	}
+	got, _ = store.Get(created.ID)
+	if got.Status != ticket.StatusTodo || got.Title != "A" {
+		t.Fatalf("undo got %+v", got)
+	}
+}
diff --git a/internal/command/ticket_cmds.go b/internal/command/ticket_cmds.go
new file mode 100644
index 0000000..b792695
--- /dev/null
+++ b/internal/command/ticket_cmds.go
@@ -0,0 +1,81 @@
+package command
+
+import (
+	"context"
+	"fmt"
+
+	"task/internal/ticket"
+)
+
+// CreateTicket creates a ticket; Undo deletes it.
+type CreateTicket struct {
+	Store  ticket.Store
+	Ticket ticket.Ticket
+	created ticket.Ticket
+}
+
+func (c *CreateTicket) Name() string { return "create ticket" }
+
+func (c *CreateTicket) Execute(ctx context.Context) error {
+	_ = ctx
+	created, err := c.Store.Create(c.Ticket)
+	if err != nil {
+		return err
+	}
+	c.created = created
+	c.Ticket = created
+	return nil
+}
+
+func (c *CreateTicket) Undo(ctx context.Context) error {
+	_ = ctx
+	id := c.created.ID
+	if id == "" {
+		id = c.Ticket.ID
+	}
+	if id == "" {
+		return fmt.Errorf("create undo: missing ticket id")
+	}
+	return c.Store.Delete(id)
+}
+
+// DeleteTicket deletes a ticket; Undo restores the snapshot.
+type DeleteTicket struct {
+	Store    ticket.Store
+	Snapshot ticket.Ticket
+}
+
+func (c *DeleteTicket) Name() string { return "delete ticket" }
+
+func (c *DeleteTicket) Execute(ctx context.Context) error {
+	_ = ctx
+	if c.Snapshot.ID == "" {
+		return fmt.Errorf("delete: missing ticket id")
+	}
+	return c.Store.Delete(c.Snapshot.ID)
+}
+
+func (c *DeleteTicket) Undo(ctx context.Context) error {
+	_ = ctx
+	_, err := c.Store.Create(c.Snapshot)
+	return err
+}
+
+// UpdateTicket applies a new ticket state; Undo restores Before.
+type UpdateTicket struct {
+	Store  ticket.Store
+	Before ticket.Ticket
+	After  ticket.Ticket
+}
+
+func (c *UpdateTicket) Name() string { return "update ticket" }
+
+func (c *UpdateTicket) Execute(ctx context.Context) error {
+	_ = ctx
+	return c.Store.Update(c.After)
+}
+
+func (c *UpdateTicket) Undo(ctx context.Context) error {
+	_ = ctx
+	return c.Store.Update(c.Before)
+}
diff --git a/internal/config/config.go b/internal/config/config.go
new file mode 100644
index 0000000..a6d0907
--- /dev/null
+++ b/internal/config/config.go
@@ -0,0 +1,75 @@
+package config
+
+import "path/filepath"
+
+const (
+	AppName         = "task-master"
+	DefaultProject  = "inbox"
+	DefaultTheme    = "default"
+	configFileName  = "config.json"
+)
+
+// Config holds application settings persisted under ~/.config/task-master.
+type Config struct {
+	ActiveProject string            `json:"activeProject"`
+	DataDir       string            `json:"dataDir"`
+	Theme         string            `json:"theme"`
+	// ProjectLists maps project ID → board list id (all|backlog|in_progress|done).
+	ProjectLists map[string]string `json:"projectLists,omitempty"`
+}
+
+// Path returns the absolute path to the config file.
+func Path(home string) string {
+	return filepath.Join(home, ".config", AppName, configFileName)
+}
+
+// DefaultDataDir returns the default data directory under ~/.local/share.
+func DefaultDataDir(home string) string {
+	return filepath.Join(home, ".local", "share", AppName)
+}
+
+// Defaults returns a Config with sensible defaults for the given home directory.
+func Defaults(home string) Config {
+	return Config{
+		ActiveProject: DefaultProject,
+		DataDir:       DefaultDataDir(home),
+		Theme:         DefaultTheme,
+		ProjectLists:  map[string]string{},
+	}
+}
+
+// ApplyDefaults fills empty fields from defaults without overwriting set values.
+func (c *Config) ApplyDefaults(home string) {
+	d := Defaults(home)
+	if c.ActiveProject == "" {
+		c.ActiveProject = d.ActiveProject
+	}
+	if c.DataDir == "" {
+		c.DataDir = d.DataDir
+	}
+	if c.Theme == "" {
+		c.Theme = d.Theme
+	}
+	if c.ProjectLists == nil {
+		c.ProjectLists = map[string]string{}
+	}
+}
+
+// ActiveBoardList returns the persisted board list for a project (default: all).
+func (c *Config) ActiveBoardList(projectID string) string {
+	if c.ProjectLists == nil {
+		return "all"
+	}
+	if v, ok := c.ProjectLists[projectID]; ok && v != "" {
+		return v
+	}
+	return "all"
+}
+
+// SetActiveBoardList stores the board list for a project.
+func (c *Config) SetActiveBoardList(projectID, listID string) {
+	if c.ProjectLists == nil {
+		c.ProjectLists = map[string]string{}
+	}
+	c.ProjectLists[projectID] = listID
+}
diff --git a/internal/config/loader.go b/internal/config/loader.go
new file mode 100644
index 0000000..d0cecc6
--- /dev/null
+++ b/internal/config/loader.go
@@ -0,0 +1,90 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// LoadOrCreate loads the config from disk, creating defaults if missing.
+// It also ensures DataDir and the active project directory exist.
+func LoadOrCreate() (*Config, error) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return nil, fmt.Errorf("resolve home directory: %w", err)
+	}
+
+	cfgPath := Path(home)
+	cfgDir := filepath.Dir(cfgPath)
+	if err := os.MkdirAll(cfgDir, 0o755); err != nil {
+		return nil, fmt.Errorf("create config dir %s: %w", cfgDir, err)
+	}
+
+	cfg, err := readOrCreate(cfgPath, home)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := ensureDataDirs(cfg); err != nil {
+		return nil, err
+	}
+
+	return cfg, nil
+}
+
+func readOrCreate(cfgPath, home string) (*Config, error) {
+	data, err := os.ReadFile(cfgPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			cfg := Defaults(home)
+			if err := Save(&cfg); err != nil {
+				return nil, fmt.Errorf("write default config: %w", err)
+			}
+			return &cfg, nil
+		}
+		return nil, fmt.Errorf("read config %s: %w", cfgPath, err)
+	}
+
+	var cfg Config
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return nil, fmt.Errorf("parse config %s: %w", cfgPath, err)
+	}
+	cfg.ApplyDefaults(home)
+	return &cfg, nil
+}
+
+// Save writes the config to ~/.config/task-master/config.json.
+func Save(cfg *Config) error {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return fmt.Errorf("resolve home directory: %w", err)
+	}
+
+	cfgPath := Path(home)
+	if err := os.MkdirAll(filepath.Dir(cfgPath), 0o755); err != nil {
+		return fmt.Errorf("create config dir: %w", err)
+	}
+
+	data, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return fmt.Errorf("marshal config: %w", err)
+	}
+	data = append(data, '\n')
+
+	if err := os.WriteFile(cfgPath, data, 0o644); err != nil {
+		return fmt.Errorf("write config %s: %w", cfgPath, err)
+	}
+	return nil
+}
+
+func ensureDataDirs(cfg *Config) error {
+	if err := os.MkdirAll(cfg.DataDir, 0o755); err != nil {
+		return fmt.Errorf("create data dir %s: %w", cfg.DataDir, err)
+	}
+	projectDir := filepath.Join(cfg.DataDir, "projects", cfg.ActiveProject)
+	if err := os.MkdirAll(projectDir, 0o755); err != nil {
+		return fmt.Errorf("create project dir %s: %w", projectDir, err)
+	}
+	return nil
+}
diff --git a/internal/config/loader_test.go b/internal/config/loader_test.go
new file mode 100644
index 0000000..d1ed440
--- /dev/null
+++ b/internal/config/loader_test.go
@@ -0,0 +1,83 @@
+package config_test
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"task/internal/config"
+)
+
+func TestDefaultsAndApplyDefaults(t *testing.T) {
+	home := "/tmp/fake-home"
+	cfg := config.Defaults(home)
+	if cfg.ActiveProject != config.DefaultProject {
+		t.Fatalf("ActiveProject = %q", cfg.ActiveProject)
+	}
+	wantData := filepath.Join(home, ".local", "share", config.AppName)
+	if cfg.DataDir != wantData {
+		t.Fatalf("DataDir = %q, want %q", cfg.DataDir, wantData)
+	}
+
+	partial := config.Config{}
+	partial.ApplyDefaults(home)
+	if partial.ActiveProject != config.DefaultProject || partial.DataDir != wantData {
+		t.Fatalf("ApplyDefaults failed: %+v", partial)
+	}
+}
+
+func TestSaveRoundTrip(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	cfg := config.Defaults(home)
+	cfg.ActiveProject = "work"
+	if err := config.Save(&cfg); err != nil {
+		t.Fatalf("Save: %v", err)
+	}
+
+	path := config.Path(home)
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("ReadFile: %v", err)
+	}
+	var got config.Config
+	if err := json.Unmarshal(data, &got); err != nil {
+		t.Fatalf("Unmarshal: %v", err)
+	}
+	if got.ActiveProject != "work" {
+		t.Fatalf("ActiveProject = %q", got.ActiveProject)
+	}
+}
+
+func TestLoadOrCreate(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+
+	cfg, err := config.LoadOrCreate()
+	if err != nil {
+		t.Fatalf("LoadOrCreate: %v", err)
+	}
+	if cfg.ActiveProject != config.DefaultProject {
+		t.Fatalf("ActiveProject = %q", cfg.ActiveProject)
+	}
+
+	cfgPath := config.Path(home)
+	if _, err := os.Stat(cfgPath); err != nil {
+		t.Fatalf("config file missing: %v", err)
+	}
+	projectDir := filepath.Join(cfg.DataDir, "projects", cfg.ActiveProject)
+	if st, err := os.Stat(projectDir); err != nil || !st.IsDir() {
+		t.Fatalf("project dir missing: %v", err)
+	}
+
+	// Second call loads existing
+	cfg2, err := config.LoadOrCreate()
+	if err != nil {
+		t.Fatalf("LoadOrCreate 2: %v", err)
+	}
+	if cfg2.DataDir != cfg.DataDir {
+		t.Fatalf("DataDir mismatch")
+	}
+}
diff --git a/internal/project/project.go b/internal/project/project.go
new file mode 100644
index 0000000..9982a74
--- /dev/null
+++ b/internal/project/project.go
@@ -0,0 +1,7 @@
+package project
+
+// Project is a lightweight workspace identified by a directory name.
+type Project struct {
+	ID   string `json:"id"`
+	Name string `json:"name"`
+}
diff --git a/internal/project/store.go b/internal/project/store.go
new file mode 100644
index 0000000..43e6edc
--- /dev/null
+++ b/internal/project/store.go
@@ -0,0 +1,65 @@
+package project
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+)
+
+// Store manages project directories under DataDir/projects.
+type Store interface {
+	List() ([]Project, error)
+	Ensure(id string) error
+}
+
+// DirStore discovers projects as subdirectories of dataDir/projects.
+type DirStore struct {
+	dataDir string
+}
+
+// NewDirStore creates a project store rooted at dataDir.
+func NewDirStore(dataDir string) *DirStore {
+	return &DirStore{dataDir: dataDir}
+}
+
+func (s *DirStore) projectsRoot() string {
+	return filepath.Join(s.dataDir, "projects")
+}
+
+// List returns all project directories, sorted by name.
+func (s *DirStore) List() ([]Project, error) {
+	root := s.projectsRoot()
+	entries, err := os.ReadDir(root)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return []Project{}, nil
+		}
+		return nil, fmt.Errorf("list projects: %w", err)
+	}
+
+	var projects []Project
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		name := e.Name()
+		projects = append(projects, Project{ID: name, Name: name})
+	}
+	sort.Slice(projects, func(i, j int) bool {
+		return projects[i].Name < projects[j].Name
+	})
+	return projects, nil
+}
+
+// Ensure creates the project directory if it does not exist.
+func (s *DirStore) Ensure(id string) error {
+	if id == "" {
+		return fmt.Errorf("project id is required")
+	}
+	dir := filepath.Join(s.projectsRoot(), id)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return fmt.Errorf("create project %s: %w", id, err)
+	}
+	return nil
+}
diff --git a/internal/ticket/board.go b/internal/ticket/board.go
new file mode 100644
index 0000000..6bbb8a4
--- /dev/null
+++ b/internal/ticket/board.go
@@ -0,0 +1,79 @@
+package ticket
+
+// BoardList is a project-scoped view/filter over tickets by status.
+type BoardList string
+
+const (
+	BoardAll        BoardList = "all"
+	BoardBacklog    BoardList = "backlog"
+	BoardInProgress BoardList = "in_progress"
+	BoardDone       BoardList = "done"
+)
+
+// AllBoardLists is the ordered picker list.
+var AllBoardLists = []BoardList{BoardAll, BoardBacklog, BoardInProgress, BoardDone}
+
+// Label returns a display name for the board list.
+func (b BoardList) Label() string {
+	switch b {
+	case BoardAll:
+		return "All"
+	case BoardBacklog:
+		return "Backlog"
+	case BoardInProgress:
+		return "In Progress"
+	case BoardDone:
+		return "Done"
+	default:
+		return string(b)
+	}
+}
+
+// Index returns the position in AllBoardLists.
+func (b BoardList) Index() int {
+	for i, bl := range AllBoardLists {
+		if bl == b {
+			return i
+		}
+	}
+	return 0
+}
+
+// ParseBoardList validates a board list id; invalid values become BoardAll.
+func ParseBoardList(s string) BoardList {
+	b := BoardList(s)
+	switch b {
+	case BoardAll, BoardBacklog, BoardInProgress, BoardDone:
+		return b
+	default:
+		return BoardAll
+	}
+}
+
+// Matches reports whether a ticket belongs on this board list.
+func (b BoardList) Matches(status Status) bool {
+	switch b {
+	case BoardAll:
+		return true
+	case BoardBacklog:
+		return status == StatusTodo
+	case BoardInProgress:
+		return status == StatusInProgress
+	case BoardDone:
+		return status == StatusDone
+	default:
+		return true
+	}
+}
+
+// DefaultStatus is the status used when creating a ticket on this list.
+func (b BoardList) DefaultStatus() Status {
+	switch b {
+	case BoardInProgress:
+		return StatusInProgress
+	case BoardDone:
+		return StatusDone
+	default:
+		return StatusTodo
+	}
+}
diff --git a/internal/ticket/board_test.go b/internal/ticket/board_test.go
new file mode 100644
index 0000000..5b5bda3
--- /dev/null
+++ b/internal/ticket/board_test.go
@@ -0,0 +1,43 @@
+package ticket_test
+
+import (
+	"testing"
+
+	"task/internal/ticket"
+)
+
+func TestBoardListMatches(t *testing.T) {
+	cases := []struct {
+		list   ticket.BoardList
+		status ticket.Status
+		want   bool
+	}{
+		{ticket.BoardAll, ticket.StatusTodo, true},
+		{ticket.BoardAll, ticket.StatusDone, true},
+		{ticket.BoardBacklog, ticket.StatusTodo, true},
+		{ticket.BoardBacklog, ticket.StatusInProgress, false},
+		{ticket.BoardInProgress, ticket.StatusInProgress, true},
+		{ticket.BoardDone, ticket.StatusDone, true},
+		{ticket.BoardDone, ticket.StatusTodo, false},
+	}
+	for _, tc := range cases {
+		if got := tc.list.Matches(tc.status); got != tc.want {
+			t.Errorf("%s.Matches(%s) = %v, want %v", tc.list, tc.status, got, tc.want)
+		}
+	}
+}
+
+func TestBoardListDefaultStatus(t *testing.T) {
+	if ticket.BoardBacklog.DefaultStatus() != ticket.StatusTodo {
+		t.Fatal("backlog default")
+	}
+	if ticket.BoardInProgress.DefaultStatus() != ticket.StatusInProgress {
+		t.Fatal("in progress default")
+	}
+	if ticket.BoardDone.DefaultStatus() != ticket.StatusDone {
+		t.Fatal("done default")
+	}
+	if ticket.BoardAll.DefaultStatus() != ticket.StatusTodo {
+		t.Fatal("all default")
+	}
+}
diff --git a/internal/ticket/editfile.go b/internal/ticket/editfile.go
new file mode 100644
index 0000000..e157790
--- /dev/null
+++ b/internal/ticket/editfile.go
@@ -0,0 +1,105 @@
+package ticket
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+// FormatEditDocument is the markdown representation used for external editing.
+// Format:
+//
+//	# Title
+//
+//	optional description body…
+func FormatEditDocument(t Ticket) string {
+	title := strings.TrimSpace(t.Title)
+	title = strings.TrimLeft(title, "#")
+	title = strings.TrimSpace(title)
+
+	var b strings.Builder
+	b.WriteString("# ")
+	b.WriteString(title)
+	b.WriteString("\n")
+	if desc := strings.TrimSpace(t.Description); desc != "" {
+		b.WriteString("\n")
+		b.WriteString(desc)
+		if !strings.HasSuffix(desc, "\n") {
+			b.WriteString("\n")
+		}
+	}
+	return b.String()
+}
+
+// ParseEditDocument extracts title and description from an edited markdown file.
+func ParseEditDocument(content string) (title, description string, err error) {
+	content = strings.ReplaceAll(content, "\r\n", "\n")
+	content = strings.TrimSpace(content)
+	if content == "" {
+		return "", "", fmt.Errorf("ticket content is empty")
+	}
+
+	lines := strings.Split(content, "\n")
+	first := strings.TrimSpace(lines[0])
+	if strings.HasPrefix(first, "#") {
+		title = strings.TrimSpace(strings.TrimLeft(first, "#"))
+		rest := strings.Join(lines[1:], "\n")
+		description = strings.TrimSpace(rest)
+	} else {
+		title = first
+		rest := strings.Join(lines[1:], "\n")
+		description = strings.TrimSpace(rest)
+	}
+	if title == "" {
+		return "", "", fmt.Errorf("ticket title is required")
+	}
+	return title, description, nil
+}
+
+// WriteEditFile writes the ticket to a temp .md file and returns its path.
+func WriteEditFile(t Ticket) (string, error) {
+	f, err := os.CreateTemp("", "task-master-ticket-*.md")
+	if err != nil {
+		return "", fmt.Errorf("create temp file: %w", err)
+	}
+	path := f.Name()
+	if _, err := f.WriteString(FormatEditDocument(t)); err != nil {
+		_ = f.Close()
+		_ = os.Remove(path)
+		return "", fmt.Errorf("write temp file: %w", err)
+	}
+	if err := f.Close(); err != nil {
+		_ = os.Remove(path)
+		return "", fmt.Errorf("close temp file: %w", err)
+	}
+	return path, nil
+}
+
+// ResolveEditor returns the user's preferred editor command string.
+// Order: $EDITOR → $VISUAL → nvim → vim → vi.
+func ResolveEditor() string {
+	if ed := strings.TrimSpace(os.Getenv("EDITOR")); ed != "" {
+		return ed
+	}
+	if ed := strings.TrimSpace(os.Getenv("VISUAL")); ed != "" {
+		return ed
+	}
+	for _, cand := range []string{"nvim", "vim", "vi"} {
+		if _, err := exec.LookPath(cand); err == nil {
+			return cand
+		}
+	}
+	return "vi"
+}
+
+// EditorCmd builds a command that opens path in the default terminal editor.
+// Supports multi-word EDITOR values like "code --wait".
+func EditorCmd(path string) *exec.Cmd {
+	ed := ResolveEditor()
+	cmd := exec.Command("sh", "-c", ed+` "$1"`, "--", path)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd
+}
diff --git a/internal/ticket/editfile_editor_test.go b/internal/ticket/editfile_editor_test.go
new file mode 100644
index 0000000..33c721d
--- /dev/null
+++ b/internal/ticket/editfile_editor_test.go
@@ -0,0 +1,34 @@
+package ticket_test
+
+import (
+	"os"
+	"os/exec"
+	"testing"
+
+	"task/internal/ticket"
+)
+
+func TestResolveEditorPrefersEnv(t *testing.T) {
+	t.Setenv("EDITOR", "custom-ed")
+	t.Setenv("VISUAL", "visual-ed")
+	if got := ticket.ResolveEditor(); got != "custom-ed" {
+		t.Fatalf("got %q, want custom-ed", got)
+	}
+}
+
+func TestResolveEditorFallsBackToNvim(t *testing.T) {
+	t.Setenv("EDITOR", "")
+	t.Setenv("VISUAL", "")
+	got := ticket.ResolveEditor()
+	if _, err := exec.LookPath("nvim"); err == nil {
+		if got != "nvim" {
+			t.Fatalf("got %q, want nvim when available", got)
+		}
+		return
+	}
+	// Without nvim, accept vim/vi.
+	if got != "vim" && got != "vi" {
+		t.Fatalf("got unexpected fallback %q", got)
+	}
+	_ = os.Environ()
+}
diff --git a/internal/ticket/editfile_test.go b/internal/ticket/editfile_test.go
new file mode 100644
index 0000000..e9fdd14
--- /dev/null
+++ b/internal/ticket/editfile_test.go
@@ -0,0 +1,45 @@
+package ticket_test
+
+import (
+	"strings"
+	"testing"
+
+	"task/internal/ticket"
+)
+
+func TestFormatAndParseEditDocument(t *testing.T) {
+	doc := ticket.FormatEditDocument(ticket.Ticket{
+		Title:       "Fix login",
+		Description: "Steps:\n\n1. repro\n2. patch",
+	})
+	if !strings.HasPrefix(doc, "# Fix login\n") {
+		t.Fatalf("format = %q", doc)
+	}
+
+	title, desc, err := ticket.ParseEditDocument(doc)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if title != "Fix login" {
+		t.Fatalf("title = %q", title)
+	}
+	if desc != "Steps:\n\n1. repro\n2. patch" {
+		t.Fatalf("desc = %q", desc)
+	}
+}
+
+func TestParseEditDocumentPlainTitle(t *testing.T) {
+	title, desc, err := ticket.ParseEditDocument("Plain title\n\nBody text")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if title != "Plain title" || desc != "Body text" {
+		t.Fatalf("got %q / %q", title, desc)
+	}
+}
+
+func TestParseEditDocumentEmpty(t *testing.T) {
+	if _, _, err := ticket.ParseEditDocument("   "); err == nil {
+		t.Fatal("expected error")
+	}
+}
diff --git a/internal/ticket/jsonstore.go b/internal/ticket/jsonstore.go
new file mode 100644
index 0000000..f3280f5
--- /dev/null
+++ b/internal/ticket/jsonstore.go
@@ -0,0 +1,245 @@
+package ticket
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+const (
+	ticketsFileName = "tickets.json"
+	legacyFileName  = "tasks.json"
+)
+
+// JSONStore persists tickets as JSON arrays under DataDir/projects/<id>/tickets.json.
+type JSONStore struct {
+	dataDir string
+	mu      sync.Mutex
+}
+
+// NewJSONStore creates a store rooted at dataDir.
+func NewJSONStore(dataDir string) *JSONStore {
+	return &JSONStore{dataDir: dataDir}
+}
+
+func (s *JSONStore) projectPath(projectID string) string {
+	return filepath.Join(s.dataDir, "projects", projectID)
+}
+
+func (s *JSONStore) ticketsPath(projectID string) string {
+	return filepath.Join(s.projectPath(projectID), ticketsFileName)
+}
+
+func (s *JSONStore) legacyPath(projectID string) string {
+	return filepath.Join(s.projectPath(projectID), legacyFileName)
+}
+
+// List returns all tickets for a project.
+func (s *JSONStore) List(projectID string) ([]Ticket, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.readUnlocked(projectID)
+}
+
+// Get finds a ticket by ID across all project directories.
+func (s *JSONStore) Get(id string) (Ticket, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	projects, err := os.ReadDir(filepath.Join(s.dataDir, "projects"))
+	if err != nil {
+		if os.IsNotExist(err) {
+			return Ticket{}, fmt.Errorf("ticket %s: not found", id)
+		}
+		return Ticket{}, fmt.Errorf("list projects: %w", err)
+	}
+
+	for _, p := range projects {
+		if !p.IsDir() {
+			continue
+		}
+		tickets, err := s.readUnlocked(p.Name())
+		if err != nil {
+			return Ticket{}, err
+		}
+		for _, t := range tickets {
+			if t.ID == id {
+				return t, nil
+			}
+		}
+	}
+	return Ticket{}, fmt.Errorf("ticket %s: not found", id)
+}
+
+// Create adds a new ticket, assigning ID and timestamps if missing.
+func (s *JSONStore) Create(t Ticket) (Ticket, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if t.ProjectID == "" {
+		return Ticket{}, fmt.Errorf("projectId is required")
+	}
+	if t.Title == "" {
+		return Ticket{}, fmt.Errorf("title is required")
+	}
+	if t.ID == "" {
+		t.ID = uuid.NewString()
+	}
+	if t.Status == "" {
+		t.Status = StatusTodo
+	}
+	now := time.Now().UTC()
+	if t.CreatedAt.IsZero() {
+		t.CreatedAt = now
+	}
+	if t.UpdatedAt.IsZero() {
+		t.UpdatedAt = now
+	}
+
+	if err := os.MkdirAll(s.projectPath(t.ProjectID), 0o755); err != nil {
+		return Ticket{}, fmt.Errorf("create project dir: %w", err)
+	}
+
+	tickets, err := s.readUnlocked(t.ProjectID)
+	if err != nil {
+		return Ticket{}, err
+	}
+	tickets = append(tickets, t)
+	if err := s.writeUnlocked(t.ProjectID, tickets); err != nil {
+		return Ticket{}, err
+	}
+	return t, nil
+}
+
+// Update replaces an existing ticket (matched by ID within its project).
+func (s *JSONStore) Update(t Ticket) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if t.ID == "" || t.ProjectID == "" {
+		return fmt.Errorf("id and projectId are required")
+	}
+
+	tickets, err := s.readUnlocked(t.ProjectID)
+	if err != nil {
+		return err
+	}
+
+	found := false
+	for i := range tickets {
+		if tickets[i].ID == t.ID {
+			t.CreatedAt = tickets[i].CreatedAt
+			t.UpdatedAt = time.Now().UTC()
+			tickets[i] = t
+			found = true
+			break
+		}
+	}
+	if !found {
+		return fmt.Errorf("ticket %s: not found", t.ID)
+	}
+	return s.writeUnlocked(t.ProjectID, tickets)
+}
+
+// Delete removes a ticket by ID from its project's file.
+func (s *JSONStore) Delete(id string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	projects, err := os.ReadDir(filepath.Join(s.dataDir, "projects"))
+	if err != nil {
+		if os.IsNotExist(err) {
+			return fmt.Errorf("ticket %s: not found", id)
+		}
+		return fmt.Errorf("list projects: %w", err)
+	}
+
+	for _, p := range projects {
+		if !p.IsDir() {
+			continue
+		}
+		tickets, err := s.readUnlocked(p.Name())
+		if err != nil {
+			return err
+		}
+		for i, t := range tickets {
+			if t.ID == id {
+				tickets = append(tickets[:i], tickets[i+1:]...)
+				return s.writeUnlocked(p.Name(), tickets)
+			}
+		}
+	}
+	return fmt.Errorf("ticket %s: not found", id)
+}
+
+func (s *JSONStore) readUnlocked(projectID string) ([]Ticket, error) {
+	path := s.ticketsPath(projectID)
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			// Migrate from legacy tasks.json if present.
+			legacy := s.legacyPath(projectID)
+			data, err = os.ReadFile(legacy)
+			if err != nil {
+				if os.IsNotExist(err) {
+					return []Ticket{}, nil
+				}
+				return nil, fmt.Errorf("read %s: %w", legacy, err)
+			}
+			path = legacy
+		} else {
+			return nil, fmt.Errorf("read %s: %w", path, err)
+		}
+	}
+	if len(data) == 0 {
+		return []Ticket{}, nil
+	}
+	var tickets []Ticket
+	if err := json.Unmarshal(data, &tickets); err != nil {
+		return nil, fmt.Errorf("parse %s: %w", path, err)
+	}
+	if tickets == nil {
+		tickets = []Ticket{}
+	}
+	return tickets, nil
+}
+
+func (s *JSONStore) writeUnlocked(projectID string, tickets []Ticket) error {
+	path := s.ticketsPath(projectID)
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return fmt.Errorf("create project dir: %w", err)
+	}
+
+	data, err := json.MarshalIndent(tickets, "", "  ")
+	if err != nil {
+		return fmt.Errorf("marshal tickets: %w", err)
+	}
+	data = append(data, '\n')
+
+	tmp, err := os.CreateTemp(filepath.Dir(path), "tickets-*.tmp")
+	if err != nil {
+		return fmt.Errorf("create temp file: %w", err)
+	}
+	tmpName := tmp.Name()
+	defer func() { _ = os.Remove(tmpName) }()
+
+	if _, err := tmp.Write(data); err != nil {
+		_ = tmp.Close()
+		return fmt.Errorf("write temp file: %w", err)
+	}
+	if err := tmp.Close(); err != nil {
+		return fmt.Errorf("close temp file: %w", err)
+	}
+	if err := os.Rename(tmpName, path); err != nil {
+		return fmt.Errorf("rename temp to %s: %w", path, err)
+	}
+
+	// Clean up legacy file after successful write to tickets.json.
+	_ = os.Remove(s.legacyPath(projectID))
+	return nil
+}
diff --git a/internal/ticket/jsonstore_test.go b/internal/ticket/jsonstore_test.go
new file mode 100644
index 0000000..670aac4
--- /dev/null
+++ b/internal/ticket/jsonstore_test.go
@@ -0,0 +1,99 @@
+package ticket_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"task/internal/ticket"
+)
+
+func TestJSONStoreCreateListUpdate(t *testing.T) {
+	dir := t.TempDir()
+	store := ticket.NewJSONStore(dir)
+
+	created, err := store.Create(ticket.Ticket{
+		Title:     "Write tests",
+		ProjectID: "inbox",
+	})
+	if err != nil {
+		t.Fatalf("Create: %v", err)
+	}
+	if created.ID == "" {
+		t.Fatal("expected ID to be set")
+	}
+	if created.Status != ticket.StatusTodo {
+		t.Fatalf("status = %s, want todo", created.Status)
+	}
+
+	list, err := store.List("inbox")
+	if err != nil {
+		t.Fatalf("List: %v", err)
+	}
+	if len(list) != 1 {
+		t.Fatalf("len(list) = %d, want 1", len(list))
+	}
+
+	path := filepath.Join(dir, "projects", "inbox", "tickets.json")
+	if _, err := os.Stat(path); err != nil {
+		t.Fatalf("tickets.json missing: %v", err)
+	}
+
+	created.Status = ticket.StatusDone
+	created.Title = "Write better tests"
+	if err := store.Update(created); err != nil {
+		t.Fatalf("Update: %v", err)
+	}
+
+	got, err := store.Get(created.ID)
+	if err != nil {
+		t.Fatalf("Get: %v", err)
+	}
+	if got.Status != ticket.StatusDone || got.Title != "Write better tests" {
+		t.Fatalf("got %+v", got)
+	}
+
+	if err := store.Delete(created.ID); err != nil {
+		t.Fatalf("Delete: %v", err)
+	}
+	list, err = store.List("inbox")
+	if err != nil {
+		t.Fatalf("List after delete: %v", err)
+	}
+	if len(list) != 0 {
+		t.Fatalf("len(list) = %d, want 0", len(list))
+	}
+}
+
+func TestJSONStoreMigratesLegacyTasksJSON(t *testing.T) {
+	dir := t.TempDir()
+	projectDir := filepath.Join(dir, "projects", "inbox")
+	if err := os.MkdirAll(projectDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	legacy := `[{"id":"abc","title":"Legacy","status":"todo","projectId":"inbox","createdAt":"2024-01-01T00:00:00Z","updatedAt":"2024-01-01T00:00:00Z"}]`
+	if err := os.WriteFile(filepath.Join(projectDir, "tasks.json"), []byte(legacy), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	store := ticket.NewJSONStore(dir)
+	list, err := store.List("inbox")
+	if err != nil {
+		t.Fatalf("List: %v", err)
+	}
+	if len(list) != 1 || list[0].Title != "Legacy" {
+		t.Fatalf("got %+v", list)
+	}
+
+	// Write should create tickets.json and remove legacy.
+	list[0].Title = "Migrated"
+	if err := store.Update(list[0]); err != nil {
+		t.Fatalf("Update: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(projectDir, "tickets.json")); err != nil {
+		t.Fatalf("tickets.json missing after write: %v", err)
+	}
+	if _, err := os.Stat(filepath.Join(projectDir, "tasks.json")); !os.IsNotExist(err) {
+		t.Fatalf("legacy tasks.json should be removed, err=%v", err)
+	}
+}
diff --git a/internal/ticket/store.go b/internal/ticket/store.go
new file mode 100644
index 0000000..027809b
--- /dev/null
+++ b/internal/ticket/store.go
@@ -0,0 +1,11 @@
+package ticket
+
+// Store is the persistence interface for tickets.
+// Implementations must be safe for concurrent use.
+type Store interface {
+	List(projectID string) ([]Ticket, error)
+	Get(id string) (Ticket, error)
+	Create(t Ticket) (Ticket, error)
+	Update(t Ticket) error
+	Delete(id string) error
+}
diff --git a/internal/ticket/ticket.go b/internal/ticket/ticket.go
new file mode 100644
index 0000000..f2bbc6b
--- /dev/null
+++ b/internal/ticket/ticket.go
@@ -0,0 +1,51 @@
+package ticket
+
+import "time"
+
+// Status represents the workflow state of a ticket.
+type Status string
+
+const (
+	StatusTodo       Status = "todo"
+	StatusInProgress Status = "in_progress"
+	StatusDone       Status = "done"
+)
+
+// AllStatuses is the ordered list shown in the status picker.
+var AllStatuses = []Status{StatusTodo, StatusInProgress, StatusDone}
+
+// Label returns a short display label for the status.
+func (s Status) Label() string {
+	switch s {
+	case StatusTodo:
+		return "OPEN"
+	case StatusInProgress:
+		return "WIP"
+	case StatusDone:
+		return "DONE"
+	default:
+		return string(s)
+	}
+}
+
+// Index returns the position in AllStatuses, or 0 if unknown.
+func (s Status) Index() int {
+	for i, st := range AllStatuses {
+		if st == s {
+			return i
+		}
+	}
+	return 0
+}
+
+// Ticket is the domain model for a work item.
+// Title (headline) and Description are Markdown.
+type Ticket struct {
+	ID          string    `json:"id"`
+	Title       string    `json:"title"`
+	Description string    `json:"description,omitempty"`
+	Status      Status    `json:"status"`
+	ProjectID   string    `json:"projectId"`
+	CreatedAt   time.Time `json:"createdAt"`
+	UpdatedAt   time.Time `json:"updatedAt"`
+}
diff --git a/internal/ui/app.go b/internal/ui/app.go
new file mode 100644
index 0000000..879ad62
--- /dev/null
+++ b/internal/ui/app.go
@@ -0,0 +1,694 @@
+package ui
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/charmbracelet/bubbles/key"
+	"github.com/charmbracelet/bubbles/list"
+	"github.com/charmbracelet/bubbles/textinput"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+
+	"task/internal/command"
+	"task/internal/config"
+	"task/internal/project"
+	"task/internal/ticket"
+	"task/internal/ui/views"
+	"task/internal/version"
+)
+
+// editorFinishedMsg is sent after the external $EDITOR exits.
+type editorFinishedMsg struct {
+	ticketID string
+	path     string
+	err      error
+}
+
+// Mode is the active UI mode.
+type Mode int
+
+const (
+	ModeList Mode = iota
+	ModeCreate
+	ModeSearch
+	ModeProjects
+	ModeStatus
+	ModeBoard
+)
+
+// Model is the root Bubble Tea model.
+type Model struct {
+	cfg      *config.Config
+	store    ticket.Store
+	projects project.Store
+	exec     command.Executor
+
+	mode            Mode
+	tickets         views.TicketList
+	projectList     list.Model
+	statusMenu      views.StatusMenu
+	boardMenu       views.BoardMenu
+	boardList       ticket.BoardList
+	input           textinput.Model
+	width           int
+	height          int
+	status          string
+	statusIsError   bool
+	filter          string
+	keys            KeyMap
+	styles          Styles
+	version         string
+	allTickets      []ticket.Ticket
+	creatingProject bool
+}
+
+// New creates the root UI model.
+func New(cfg *config.Config, store ticket.Store, projects project.Store, exec command.Executor) Model {
+	styles := DefaultStyles()
+	if exec == nil {
+		exec = command.NewHistory()
+	}
+
+	m := Model{
+		cfg:       cfg,
+		store:     store,
+		projects:  projects,
+		exec:      exec,
+		mode:      ModeList,
+		boardList: ticket.ParseBoardList(cfg.ActiveBoardList(cfg.ActiveProject)),
+		tickets: views.TicketList{
+			Styles: views.TicketListStyles{
+				Card:         styles.Card,
+				CardSelected: styles.CardSelected,
+				StatusOPEN:   styles.StatusTodo,
+				StatusWIP:    styles.StatusWIP,
+				StatusDONE:   styles.StatusDone,
+				Headline:     styles.Headline,
+			},
+		},
+		input:   views.NewCreateInput(),
+		keys:    DefaultKeyMap(),
+		styles:  styles,
+		version: version.BuildVersion,
+	}
+	_ = m.reloadTickets()
+	return m
+}
+
+// Init implements tea.Model.
+func (m Model) Init() tea.Cmd {
+	return nil
+}
+
+// Update implements tea.Model.
+func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.WindowSizeMsg:
+		m.width = msg.Width
+		m.height = msg.Height
+		m.resizeLists()
+		return m, nil
+
+	case editorFinishedMsg:
+		return m.handleEditorFinished(msg)
+
+	case tea.KeyMsg:
+		switch m.mode {
+		case ModeCreate, ModeSearch:
+			return m.updateInput(msg)
+		case ModeProjects:
+			return m.updateProjects(msg)
+		case ModeStatus:
+			return m.updateStatus(msg)
+		case ModeBoard:
+			return m.updateBoard(msg)
+		default:
+			return m.updateList(msg)
+		}
+	}
+
+	var cmd tea.Cmd
+	switch m.mode {
+	case ModeProjects:
+		m.projectList, cmd = m.projectList.Update(msg)
+	case ModeCreate, ModeSearch:
+		m.input, cmd = m.input.Update(msg)
+	}
+	return m, cmd
+}
+
+// View implements tea.Model.
+func (m Model) View() string {
+	if m.width == 0 {
+		return "loading…"
+	}
+	header := m.renderHeader()
+	footer := m.renderFooter()
+	bodyH := m.height - lipgloss.Height(header) - lipgloss.Height(footer)
+	if bodyH < 1 {
+		bodyH = 1
+	}
+	body := m.renderBody(bodyH)
+	return lipgloss.JoinVertical(lipgloss.Left, header, body, footer)
+}
+
+func (m *Model) resizeLists() {
+	headerH := 1
+	footerH := 1
+	bodyH := m.height - headerH - footerH
+	if bodyH < 1 {
+		bodyH = 1
+	}
+	m.tickets.SetSize(m.width, bodyH)
+	if m.mode == ModeProjects {
+		m.projectList.SetSize(m.width, bodyH)
+	}
+	m.input.Width = max(10, m.width-4)
+	m.statusMenu.Width = m.width
+	m.boardMenu.Width = m.width
+}
+
+func (m Model) updateList(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch {
+	case key.Matches(msg, m.keys.Quit):
+		return m, tea.Quit
+
+	case key.Matches(msg, m.keys.New):
+		m.clearStatus()
+		m.creatingProject = false
+		m.mode = ModeCreate
+		m.input = views.NewCreateInput()
+		m.input.Focus()
+		return m, textinput.Blink
+
+	case key.Matches(msg, m.keys.Search):
+		m.clearStatus()
+		m.creatingProject = false
+		m.mode = ModeSearch
+		m.input = views.NewSearchInput()
+		m.input.SetValue(m.filter)
+		m.input.Focus()
+		return m, textinput.Blink
+
+	case key.Matches(msg, m.keys.Project):
+		m.clearStatus()
+		if err := m.openProjects(); err != nil {
+			m.setError(err)
+			return m, nil
+		}
+		m.mode = ModeProjects
+		return m, nil
+
+	case key.Matches(msg, m.keys.Board):
+		m.clearStatus()
+		m.boardMenu = views.NewBoardMenu(m.boardList, m.width, views.StatusMenuStyles{
+			Box:      m.styles.StatusMenuBox,
+			Title:    m.styles.StatusMenuTitle,
+			Selected: m.styles.StatusMenuSelected,
+			Normal:   m.styles.StatusMenuNormal,
+		})
+		m.mode = ModeBoard
+		return m, nil
+
+	case key.Matches(msg, m.keys.Delete):
+		m.clearStatus()
+		if err := m.deleteSelected(); err != nil {
+			m.setError(err)
+		} else {
+			m.setStatus("deleted")
+		}
+		return m, nil
+
+	case key.Matches(msg, m.keys.Undo):
+		m.clearStatus()
+		if err := m.undo(); err != nil {
+			m.setError(err)
+		}
+		return m, nil
+
+	case key.Matches(msg, m.keys.Redo):
+		m.clearStatus()
+		if err := m.redo(); err != nil {
+			m.setError(err)
+		}
+		return m, nil
+
+	case key.Matches(msg, m.keys.Edit):
+		m.clearStatus()
+		cmd, err := m.openEditorForSelected()
+		if err != nil {
+			m.setError(err)
+			return m, nil
+		}
+		return m, cmd
+
+	case key.Matches(msg, m.keys.Status):
+		m.clearStatus()
+		t, ok := m.tickets.Selected()
+		if !ok {
+			m.setError(fmt.Errorf("no ticket selected"))
+			return m, nil
+		}
+		m.statusMenu = views.NewStatusMenu(t.Status, m.width, views.StatusMenuStyles{
+			Box:      m.styles.StatusMenuBox,
+			Title:    m.styles.StatusMenuTitle,
+			Selected: m.styles.StatusMenuSelected,
+			Normal:   m.styles.StatusMenuNormal,
+		})
+		m.mode = ModeStatus
+		return m, nil
+
+	case key.Matches(msg, m.keys.Down):
+		m.tickets.MoveDown()
+		return m, nil
+
+	case key.Matches(msg, m.keys.Up):
+		m.tickets.MoveUp()
+		return m, nil
+	}
+
+	return m, nil
+}
+
+func (m Model) updateStatus(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch {
+	case key.Matches(msg, m.keys.Escape):
+		m.mode = ModeList
+		m.clearStatus()
+		return m, nil
+
+	case key.Matches(msg, m.keys.Enter):
+		if err := m.applyStatus(m.statusMenu.Selected()); err != nil {
+			m.setError(err)
+			return m, nil
+		}
+		m.mode = ModeList
+		return m, nil
+
+	case key.Matches(msg, m.keys.Down):
+		m.statusMenu.MoveDown()
+		return m, nil
+
+	case key.Matches(msg, m.keys.Up):
+		m.statusMenu.MoveUp()
+		return m, nil
+	}
+	return m, nil
+}
+
+func (m Model) updateBoard(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch {
+	case key.Matches(msg, m.keys.Escape):
+		m.mode = ModeList
+		m.clearStatus()
+		return m, nil
+
+	case key.Matches(msg, m.keys.Enter):
+		if err := m.applyBoardList(m.boardMenu.Selected()); err != nil {
+			m.setError(err)
+			return m, nil
+		}
+		m.mode = ModeList
+		return m, nil
+
+	case key.Matches(msg, m.keys.Down):
+		m.boardMenu.MoveDown()
+		return m, nil
+
+	case key.Matches(msg, m.keys.Up):
+		m.boardMenu.MoveUp()
+		return m, nil
+	}
+	return m, nil
+}
+
+func (m Model) updateInput(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch {
+	case key.Matches(msg, m.keys.Escape):
+		wasProject := m.creatingProject
+		m.creatingProject = false
+		m.input.Blur()
+		m.clearStatus()
+		if wasProject {
+			m.mode = ModeProjects
+		} else {
+			m.mode = ModeList
+		}
+		return m, nil
+
+	case key.Matches(msg, m.keys.Enter):
+		value := strings.TrimSpace(m.input.Value())
+		if m.mode == ModeCreate {
+			if value == "" {
+				m.setError(fmt.Errorf("name required"))
+				return m, nil
+			}
+			if m.creatingProject {
+				id := sanitizeProjectID(value)
+				if err := m.projects.Ensure(id); err != nil {
+					m.setError(err)
+					return m, nil
+				}
+				if err := m.switchProject(id); err != nil {
+					m.setError(err)
+					return m, nil
+				}
+				m.creatingProject = false
+				m.mode = ModeList
+				m.input.Blur()
+				m.setStatus(fmt.Sprintf("created project %s", id))
+				return m, nil
+			}
+			if err := m.createTicket(value); err != nil {
+				m.setError(err)
+				return m, nil
+			}
+			m.mode = ModeList
+			m.input.Blur()
+			m.setStatus("created")
+			return m, nil
+		}
+		m.filter = value
+		m.applyFilter()
+		m.mode = ModeList
+		m.input.Blur()
+		if value == "" {
+			m.setStatus("filter cleared")
+		} else {
+			m.setStatus(fmt.Sprintf("filter: %q", value))
+		}
+		return m, nil
+	}
+
+	var cmd tea.Cmd
+	m.input, cmd = m.input.Update(msg)
+	return m, cmd
+}
+
+func (m Model) updateProjects(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	switch {
+	case key.Matches(msg, m.keys.Escape):
+		m.mode = ModeList
+		m.clearStatus()
+		return m, nil
+
+	case key.Matches(msg, m.keys.New):
+		m.clearStatus()
+		m.creatingProject = true
+		m.mode = ModeCreate
+		m.input = views.NewCreateInput()
+		m.input.Placeholder = "Project name…"
+		m.input.Focus()
+		return m, textinput.Blink
+
+	case key.Matches(msg, m.keys.Enter):
+		item, ok := m.projectList.SelectedItem().(views.ProjectItem)
+		if !ok {
+			return m, nil
+		}
+		if err := m.switchProject(item.Project.ID); err != nil {
+			m.setError(err)
+			return m, nil
+		}
+		m.mode = ModeList
+		m.setStatus(fmt.Sprintf("switched to %s", item.Project.ID))
+		return m, nil
+	}
+
+	var cmd tea.Cmd
+	m.projectList, cmd = m.projectList.Update(msg)
+	return m, cmd
+}
+
+func (m Model) openEditorForSelected() (tea.Cmd, error) {
+	t, ok := m.tickets.Selected()
+	if !ok {
+		return nil, fmt.Errorf("no ticket selected")
+	}
+	path, err := ticket.WriteEditFile(t)
+	if err != nil {
+		return nil, err
+	}
+	c := ticket.EditorCmd(path)
+	ticketID := t.ID
+	return tea.ExecProcess(c, func(err error) tea.Msg {
+		return editorFinishedMsg{ticketID: ticketID, path: path, err: err}
+	}), nil
+}
+
+func (m Model) handleEditorFinished(msg editorFinishedMsg) (tea.Model, tea.Cmd) {
+	defer func() { _ = os.Remove(msg.path) }()
+
+	if msg.err != nil {
+		m.setError(fmt.Errorf("editor: %w", msg.err))
+		return m, nil
+	}
+
+	data, err := os.ReadFile(msg.path)
+	if err != nil {
+		m.setError(fmt.Errorf("read edited file: %w", err))
+		return m, nil
+	}
+	title, description, err := ticket.ParseEditDocument(string(data))
+	if err != nil {
+		m.setError(err)
+		return m, nil
+	}
+
+	before, err := m.store.Get(msg.ticketID)
+	if err != nil {
+		m.setError(err)
+		return m, nil
+	}
+	after := before
+	after.Title = title
+	after.Description = description
+	if err := m.exec.Do(&command.UpdateTicket{
+		Store:  m.store,
+		Before: before,
+		After:  after,
+	}); err != nil {
+		m.setError(err)
+		return m, nil
+	}
+	idx := m.tickets.CursorIndex()
+	if err := m.reloadTickets(); err != nil {
+		m.setError(err)
+		return m, nil
+	}
+	if idx < m.tickets.Len() {
+		m.tickets.Select(idx)
+	}
+	m.setStatus("saved")
+	return m, nil
+}
+
+func (m *Model) createTicket(title string) error {
+	cmd := &command.CreateTicket{
+		Store: m.store,
+		Ticket: ticket.Ticket{
+			Title:     title,
+			ProjectID: m.cfg.ActiveProject,
+			Status:    m.boardList.DefaultStatus(),
+		},
+	}
+	if err := m.exec.Do(cmd); err != nil {
+		return err
+	}
+	return m.reloadTickets()
+}
+
+func (m *Model) deleteSelected() error {
+	t, ok := m.tickets.Selected()
+	if !ok {
+		return fmt.Errorf("no ticket selected")
+	}
+	idx := m.tickets.CursorIndex()
+	if err := m.exec.Do(&command.DeleteTicket{Store: m.store, Snapshot: t}); err != nil {
+		return err
+	}
+	if err := m.reloadTickets(); err != nil {
+		return err
+	}
+	if idx >= m.tickets.Len() && m.tickets.Len() > 0 {
+		m.tickets.Select(m.tickets.Len() - 1)
+	} else if idx < m.tickets.Len() {
+		m.tickets.Select(idx)
+	}
+	return nil
+}
+
+func (m *Model) applyStatus(st ticket.Status) error {
+	t, ok := m.tickets.Selected()
+	if !ok {
+		return fmt.Errorf("no ticket selected")
+	}
+	after := t
+	after.Status = st
+	if err := m.exec.Do(&command.UpdateTicket{
+		Store:  m.store,
+		Before: t,
+		After:  after,
+	}); err != nil {
+		return err
+	}
+	idx := m.tickets.CursorIndex()
+	if err := m.reloadTickets(); err != nil {
+		return err
+	}
+	if idx < m.tickets.Len() {
+		m.tickets.Select(idx)
+	}
+	m.setStatus(fmt.Sprintf("status → %s", st.Label()))
+	return nil
+}
+
+func (m *Model) undo() error {
+	name := m.exec.LastUndoName()
+	if err := m.exec.Undo(); err != nil {
+		return err
+	}
+	if err := m.reloadTickets(); err != nil {
+		return err
+	}
+	if name != "" {
+		m.setStatus("undo: " + name)
+	} else {
+		m.setStatus("undo")
+	}
+	return nil
+}
+
+func (m *Model) redo() error {
+	name := m.exec.LastRedoName()
+	if err := m.exec.Redo(); err != nil {
+		return err
+	}
+	if err := m.reloadTickets(); err != nil {
+		return err
+	}
+	if name != "" {
+		m.setStatus("redo: " + name)
+	} else {
+		m.setStatus("redo")
+	}
+	return nil
+}
+
+func (m *Model) applyBoardList(bl ticket.BoardList) error {
+	m.boardList = bl
+	m.cfg.SetActiveBoardList(m.cfg.ActiveProject, string(bl))
+	if err := config.Save(m.cfg); err != nil {
+		return err
+	}
+	m.applyFilter()
+	m.setStatus(fmt.Sprintf("list → %s", bl.Label()))
+	return nil
+}
+
+func (m *Model) switchProject(id string) error {
+	if err := m.projects.Ensure(id); err != nil {
+		return err
+	}
+	m.cfg.ActiveProject = id
+	m.boardList = ticket.ParseBoardList(m.cfg.ActiveBoardList(id))
+	if err := config.Save(m.cfg); err != nil {
+		return err
+	}
+	m.filter = ""
+	return m.reloadTickets()
+}
+
+func (m *Model) openProjects() error {
+	projects, err := m.projects.List()
+	if err != nil {
+		return err
+	}
+	if len(projects) == 0 {
+		if err := m.projects.Ensure(m.cfg.ActiveProject); err != nil {
+			return err
+		}
+		projects, err = m.projects.List()
+		if err != nil {
+			return err
+		}
+	}
+	headerH, footerH := 1, 1
+	bodyH := m.height - headerH - footerH
+	if bodyH < 1 {
+		bodyH = 1
+	}
+	m.projectList = views.NewProjectList(projects, m.cfg.ActiveProject, m.width, bodyH)
+	return nil
+}
+
+func (m *Model) reloadTickets() error {
+	tickets, err := m.store.List(m.cfg.ActiveProject)
+	if err != nil {
+		return err
+	}
+	m.allTickets = tickets
+	m.applyFilter()
+	return nil
+}
+
+func (m *Model) applyFilter() {
+	filtered := make([]ticket.Ticket, 0, len(m.allTickets))
+	for _, t := range m.allTickets {
+		if m.boardList.Matches(t.Status) {
+			filtered = append(filtered, t)
+		}
+	}
+	filtered = views.FilterTickets(filtered, m.filter)
+	cursor := m.tickets.CursorIndex()
+	m.tickets.SetItems(filtered)
+	if cursor < m.tickets.Len() {
+		m.tickets.Select(cursor)
+	}
+}
+
+func (m Model) ticketCount() int {
+	return m.tickets.Len()
+}
+
+func (m *Model) setStatus(s string) {
+	m.status = s
+	m.statusIsError = false
+}
+
+func (m *Model) setError(err error) {
+	m.status = err.Error()
+	m.statusIsError = true
+}
+
+func (m *Model) clearStatus() {
+	m.status = ""
+	m.statusIsError = false
+}
+
+func sanitizeProjectID(name string) string {
+	name = strings.TrimSpace(strings.ToLower(name))
+	var b strings.Builder
+	for _, r := range name {
+		switch {
+		case r >= 'a' && r <= 'z', r >= '0' && r <= '9', r == '-', r == '_':
+			b.WriteRune(r)
+		case r == ' ':
+			b.WriteRune('-')
+		}
+	}
+	id := b.String()
+	if id == "" {
+		return "project"
+	}
+	return id
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
diff --git a/internal/ui/helpbar.go b/internal/ui/helpbar.go
new file mode 100644
index 0000000..acf3424
--- /dev/null
+++ b/internal/ui/helpbar.go
@@ -0,0 +1,115 @@
+package ui
+
+import (
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+)
+
+type helpEntry struct {
+	key  string
+	desc string
+}
+
+func (m Model) helpEntries() []helpEntry {
+	switch m.mode {
+	case ModeCreate:
+		return []helpEntry{
+			{"enter", "save"},
+			{"esc", "cancel"},
+		}
+	case ModeSearch:
+		return []helpEntry{
+			{"enter", "apply"},
+			{"esc", "cancel"},
+		}
+	case ModeProjects:
+		return []helpEntry{
+			{"j/k", "navigate"},
+			{"enter", "select"},
+			{"n", "new project"},
+			{"esc", "cancel"},
+		}
+	case ModeStatus:
+		return []helpEntry{
+			{"j/k", "select"},
+			{"enter", "apply"},
+			{"esc", "cancel"},
+		}
+	case ModeBoard:
+		return []helpEntry{
+			{"j/k", "select"},
+			{"enter", "apply"},
+			{"esc", "cancel"},
+		}
+	default:
+		return []helpEntry{
+			{"j/k", "navigate"},
+			{"n", "new"},
+			{"e", "edit"},
+			{"u/U", "undo/redo"},
+			{"/", "search"},
+			{"p", "project"},
+			{"l", "list"},
+			{"s", "status"},
+			{"X", "delete"},
+			{"q", "quit"},
+		}
+	}
+}
+
+func (m Model) renderHelpbar() string {
+	var parts []string
+	for _, e := range m.helpEntries() {
+		parts = append(parts, m.styles.HelpKey.Render(e.key)+" "+m.styles.HelpDesc.Render(e.desc))
+	}
+	sep := m.styles.HelpSep.String()
+	if sep == "" {
+		sep = "  "
+	}
+	return strings.Join(parts, sep)
+}
+
+func (m Model) renderFooter() string {
+	help := m.renderHelpbar()
+	ver := m.styles.Version.Render(m.version)
+
+	width := m.width
+	if width <= 0 {
+		width = lipgloss.Width(help) + lipgloss.Width(ver) + 1
+	}
+
+	helpW := lipgloss.Width(help)
+	verW := lipgloss.Width(ver)
+	gap := width - helpW - verW
+	if gap < 1 {
+		maxHelp := width - verW - 1
+		if maxHelp < 0 {
+			maxHelp = 0
+		}
+		help = truncateWidth(help, maxHelp)
+		helpW = lipgloss.Width(help)
+		gap = width - helpW - verW
+		if gap < 1 {
+			gap = 1
+		}
+	}
+	return help + strings.Repeat(" ", gap) + ver
+}
+
+func truncateWidth(s string, max int) string {
+	if max <= 0 {
+		return ""
+	}
+	if lipgloss.Width(s) <= max {
+		return s
+	}
+	runes := []rune(s)
+	for len(runes) > 0 {
+		runes = runes[:len(runes)-1]
+		if lipgloss.Width(string(runes)) <= max-1 {
+			return string(runes) + "…"
+		}
+	}
+	return ""
+}
diff --git a/internal/ui/keys.go b/internal/ui/keys.go
new file mode 100644
index 0000000..e0ff283
--- /dev/null
+++ b/internal/ui/keys.go
@@ -0,0 +1,93 @@
+package ui
+
+import "github.com/charmbracelet/bubbles/key"
+
+// KeyMap defines vim-style bindings for the TUI.
+type KeyMap struct {
+	Up      key.Binding
+	Down    key.Binding
+	New     key.Binding
+	Search  key.Binding
+	Project key.Binding
+	Board   key.Binding
+	Status  key.Binding
+	Edit    key.Binding
+	Delete  key.Binding
+	Undo    key.Binding
+	Redo    key.Binding
+	Quit    key.Binding
+	Enter   key.Binding
+	Escape  key.Binding
+}
+
+// DefaultKeyMap returns the default key bindings.
+func DefaultKeyMap() KeyMap {
+	return KeyMap{
+		Up: key.NewBinding(
+			key.WithKeys("k", "up"),
+			key.WithHelp("j/k", "navigate"),
+		),
+		Down: key.NewBinding(
+			key.WithKeys("j", "down"),
+			key.WithHelp("j/k", "navigate"),
+		),
+		New: key.NewBinding(
+			key.WithKeys("n"),
+			key.WithHelp("n", "new"),
+		),
+		Search: key.NewBinding(
+			key.WithKeys("/"),
+			key.WithHelp("/", "search"),
+		),
+		Project: key.NewBinding(
+			key.WithKeys("p"),
+			key.WithHelp("p", "project"),
+		),
+		Board: key.NewBinding(
+			key.WithKeys("l", "tab"),
+			key.WithHelp("l", "list"),
+		),
+		Status: key.NewBinding(
+			key.WithKeys("s", "enter"),
+			key.WithHelp("s", "status"),
+		),
+		Edit: key.NewBinding(
+			key.WithKeys("e"),
+			key.WithHelp("e", "edit"),
+		),
+		Delete: key.NewBinding(
+			key.WithKeys("X"),
+			key.WithHelp("X", "delete"),
+		),
+		Undo: key.NewBinding(
+			key.WithKeys("u", "ctrl+z"),
+			key.WithHelp("u", "undo"),
+		),
+		Redo: key.NewBinding(
+			key.WithKeys("ctrl+r", "U"),
+			key.WithHelp("U", "redo"),
+		),
+		Quit: key.NewBinding(
+			key.WithKeys("q", "ctrl+c"),
+			key.WithHelp("q", "quit"),
+		),
+		Enter: key.NewBinding(
+			key.WithKeys("enter"),
+			key.WithHelp("enter", "confirm"),
+		),
+		Escape: key.NewBinding(
+			key.WithKeys("esc"),
+			key.WithHelp("esc", "cancel"),
+		),
+	}
+}
+
+// ShortHelp implements help.KeyMap.
+func (k KeyMap) ShortHelp() []key.Binding {
+	return []key.Binding{k.Up, k.New, k.Search, k.Project, k.Board, k.Status, k.Edit, k.Delete, k.Undo, k.Redo, k.Quit}
+}
+
+// FullHelp implements help.KeyMap.
+func (k KeyMap) FullHelp() [][]key.Binding {
+	return [][]key.Binding{k.ShortHelp()}
+}
diff --git a/internal/ui/layout.go b/internal/ui/layout.go
new file mode 100644
index 0000000..04c15e7
--- /dev/null
+++ b/internal/ui/layout.go
@@ -0,0 +1,70 @@
+package ui
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+
+	"task/internal/config"
+)
+
+func (m Model) renderHeader() string {
+	brand := m.styles.HeaderBrand.Render(config.AppName)
+	project := m.styles.HeaderMeta.Render(fmt.Sprintf("project: %s", m.cfg.ActiveProject))
+	board := m.styles.FilterHint.Render(fmt.Sprintf("list: %s", m.boardList.Label()))
+	count := m.styles.HeaderMeta.Render(fmt.Sprintf("%d tickets", m.ticketCount()))
+
+	parts := []string{brand, project, board, count}
+	if m.filter != "" {
+		parts = append(parts, m.styles.FilterHint.Render(fmt.Sprintf("filter: %q", m.filter)))
+	}
+	if m.status != "" {
+		style := m.styles.StatusMsg
+		if m.statusIsError {
+			style = m.styles.ErrorMsg
+		}
+		parts = append(parts, style.Render(m.status))
+	}
+
+	line := strings.Join(parts, m.styles.HeaderMeta.Render("  │  "))
+	return m.styles.Header.Width(m.width).Render(line)
+}
+
+func (m Model) renderBody(height int) string {
+	if height < 1 {
+		height = 1
+	}
+
+	switch m.mode {
+	case ModeCreate:
+		label := "New ticket:"
+		if m.creatingProject {
+			label = "New project:"
+		}
+		prompt := m.styles.InputPrompt.Render(label)
+		content := prompt + "\n" + m.input.View()
+		return lipgloss.NewStyle().Height(height).Width(m.width).Render(content)
+
+	case ModeSearch:
+		prompt := m.styles.InputPrompt.Render("Search:")
+		content := prompt + "\n" + m.input.View()
+		return lipgloss.NewStyle().Height(height).Width(m.width).Render(content)
+
+	case ModeProjects:
+		m.projectList.SetSize(m.width, height)
+		return m.projectList.View()
+
+	case ModeStatus:
+		menu := m.statusMenu.View()
+		return lipgloss.NewStyle().Height(height).Width(m.width).Render(menu)
+
+	case ModeBoard:
+		menu := m.boardMenu.View()
+		return lipgloss.NewStyle().Height(height).Width(m.width).Render(menu)
+
+	default:
+		m.tickets.SetSize(m.width, height)
+		return m.tickets.View()
+	}
+}
diff --git a/internal/ui/styles.go b/internal/ui/styles.go
new file mode 100644
index 0000000..d086680
--- /dev/null
+++ b/internal/ui/styles.go
@@ -0,0 +1,120 @@
+package ui
+
+import "github.com/charmbracelet/lipgloss"
+
+// Styles holds Lipgloss styles for the TUI.
+type Styles struct {
+	Header      lipgloss.Style
+	HeaderBrand lipgloss.Style
+	HeaderMeta  lipgloss.Style
+	HelpKey     lipgloss.Style
+	HelpDesc    lipgloss.Style
+	HelpSep     lipgloss.Style
+	Version     lipgloss.Style
+	StatusTodo  lipgloss.Style
+	StatusWIP   lipgloss.Style
+	StatusDone  lipgloss.Style
+	StatusMsg   lipgloss.Style
+	ErrorMsg    lipgloss.Style
+	Selected    lipgloss.Style
+	Normal      lipgloss.Style
+	InputPrompt lipgloss.Style
+	FilterHint  lipgloss.Style
+	Card        lipgloss.Style
+	CardSelected lipgloss.Style
+	Headline    lipgloss.Style
+	StatusMenuBox      lipgloss.Style
+	StatusMenuTitle    lipgloss.Style
+	StatusMenuSelected lipgloss.Style
+	StatusMenuNormal   lipgloss.Style
+}
+
+// DefaultStyles returns the neutral terminal theme.
+func DefaultStyles() Styles {
+	accent := lipgloss.Color("39")
+	faint := lipgloss.Color("245")
+	green := lipgloss.Color("42")
+	yellow := lipgloss.Color("214")
+	muted := lipgloss.Color("240")
+	border := lipgloss.Color("238")
+	borderSel := lipgloss.Color("39")
+
+	return Styles{
+		Header: lipgloss.NewStyle().
+			Bold(true).
+			Padding(0, 1),
+		HeaderBrand: lipgloss.NewStyle().
+			Bold(true).
+			Foreground(accent),
+		HeaderMeta: lipgloss.NewStyle().
+			Foreground(faint),
+		HelpKey: lipgloss.NewStyle().
+			Bold(true).
+			Foreground(accent),
+		HelpDesc: lipgloss.NewStyle().
+			Foreground(faint),
+		HelpSep: lipgloss.NewStyle().
+			Foreground(muted).
+			SetString("  "),
+		Version: lipgloss.NewStyle().
+			Faint(true).
+			Foreground(muted),
+		StatusTodo: lipgloss.NewStyle().
+			Foreground(faint).
+			Background(lipgloss.Color("236")),
+		StatusWIP: lipgloss.NewStyle().
+			Foreground(lipgloss.Color("0")).
+			Background(yellow).
+			Bold(true),
+		StatusDone: lipgloss.NewStyle().
+			Foreground(lipgloss.Color("0")).
+			Background(green),
+		StatusMsg: lipgloss.NewStyle().
+			Foreground(faint),
+		ErrorMsg: lipgloss.NewStyle().
+			Foreground(lipgloss.Color("196")),
+		Selected: lipgloss.NewStyle().
+			Foreground(lipgloss.Color("230")).
+			Background(accent).
+			Bold(true),
+		Normal: lipgloss.NewStyle(),
+		InputPrompt: lipgloss.NewStyle().
+			Foreground(accent).
+			Bold(true),
+		FilterHint: lipgloss.NewStyle().
+			Foreground(yellow),
+		// Left accent only — full box borders stacked a blank line between tickets.
+		Card: lipgloss.NewStyle().
+			BorderStyle(lipgloss.NormalBorder()).
+			BorderLeft(true).
+			BorderTop(false).
+			BorderRight(false).
+			BorderBottom(false).
+			BorderForeground(border).
+			PaddingLeft(1),
+		CardSelected: lipgloss.NewStyle().
+			BorderStyle(lipgloss.ThickBorder()).
+			BorderLeft(true).
+			BorderTop(false).
+			BorderRight(false).
+			BorderBottom(false).
+			BorderForeground(borderSel).
+			PaddingLeft(1),
+		Headline: lipgloss.NewStyle().
+			Bold(true),
+		StatusMenuBox: lipgloss.NewStyle().
+			Border(lipgloss.RoundedBorder()).
+			BorderForeground(accent).
+			Padding(1, 2),
+		StatusMenuTitle: lipgloss.NewStyle().
+			Bold(true).
+			Foreground(accent).
+			MarginBottom(1),
+		StatusMenuSelected: lipgloss.NewStyle().
+			Foreground(lipgloss.Color("230")).
+			Background(accent).
+			Bold(true),
+		StatusMenuNormal: lipgloss.NewStyle().
+			Foreground(faint),
+	}
+}
diff --git a/internal/ui/views/board.go b/internal/ui/views/board.go
new file mode 100644
index 0000000..6fcc90a
--- /dev/null
+++ b/internal/ui/views/board.go
@@ -0,0 +1,66 @@
+package views
+
+import (
+	"strings"
+
+	"task/internal/ticket"
+)
+
+// BoardMenu renders a board-list picker overlay.
+type BoardMenu struct {
+	Cursor int
+	Width  int
+	Styles StatusMenuStyles
+}
+
+// NewBoardMenu creates a menu with the given board list pre-selected.
+func NewBoardMenu(current ticket.BoardList, width int, styles StatusMenuStyles) BoardMenu {
+	return BoardMenu{
+		Cursor: current.Index(),
+		Width:  width,
+		Styles: styles,
+	}
+}
+
+// MoveDown moves the selection down.
+func (m *BoardMenu) MoveDown() {
+	if m.Cursor < len(ticket.AllBoardLists)-1 {
+		m.Cursor++
+	}
+}
+
+// MoveUp moves the selection up.
+func (m *BoardMenu) MoveUp() {
+	if m.Cursor > 0 {
+		m.Cursor--
+	}
+}
+
+// Selected returns the currently highlighted board list.
+func (m BoardMenu) Selected() ticket.BoardList {
+	if m.Cursor < 0 || m.Cursor >= len(ticket.AllBoardLists) {
+		return ticket.BoardAll
+	}
+	return ticket.AllBoardLists[m.Cursor]
+}
+
+// View renders the board menu.
+func (m BoardMenu) View() string {
+	var lines []string
+	lines = append(lines, m.Styles.Title.Render("Switch list"))
+	for i, bl := range ticket.AllBoardLists {
+		label := "  " + bl.Label()
+		if i == m.Cursor {
+			label = m.Styles.Selected.Render("▸ " + bl.Label())
+		} else {
+			label = m.Styles.Normal.Render(label)
+		}
+		lines = append(lines, label)
+	}
+	body := strings.Join(lines, "\n")
+	w := m.Width
+	if w < 20 {
+		w = 20
+	}
+	return m.Styles.Box.Width(min(40, w-2)).Render(body)
+}
diff --git a/internal/ui/views/create.go b/internal/ui/views/create.go
new file mode 100644
index 0000000..c46c936
--- /dev/null
+++ b/internal/ui/views/create.go
@@ -0,0 +1,14 @@
+package views
+
+import (
+	"github.com/charmbracelet/bubbles/textinput"
+)
+
+// NewCreateInput returns a text input configured for creating a ticket.
+func NewCreateInput() textinput.Model {
+	ti := textinput.New()
+	ti.Placeholder = "Ticket headline…"
+	ti.CharLimit = 200
+	ti.Width = 60
+	return ti
+}
diff --git a/internal/ui/views/markdown.go b/internal/ui/views/markdown.go
new file mode 100644
index 0000000..fa55bba
--- /dev/null
+++ b/internal/ui/views/markdown.go
@@ -0,0 +1,89 @@
+package views
+
+import (
+	"sync"
+
+	"github.com/charmbracelet/glamour"
+	"github.com/charmbracelet/glamour/styles"
+	"github.com/muesli/termenv"
+)
+
+type mdCacheKey struct {
+	width int
+	src   string
+}
+
+var (
+	mdMu       sync.Mutex
+	mdRenderer *glamour.TermRenderer
+	mdWidth    int
+	mdCache    = map[mdCacheKey]string{}
+)
+
+// RenderMarkdown renders Markdown to ANSI using a cached glamour renderer.
+//
+// Important: we intentionally use a fixed dark style — NOT WithAutoStyle().
+// AutoStyle calls termenv.HasDarkBackground(), which sends an OSC query to the
+// terminal and waits up to ~5s for a reply. In Cursor/some PTYs that reply
+// never arrives, so the TUI appears to hang on startup (first selected ticket
+// with a description triggers the renderer in ensureVisible/View).
+func RenderMarkdown(src string, width int) string {
+	if src == "" {
+		return ""
+	}
+	if width < 20 {
+		width = 20
+	}
+
+	key := mdCacheKey{width: width, src: src}
+	mdMu.Lock()
+	defer mdMu.Unlock()
+
+	if out, ok := mdCache[key]; ok {
+		return out
+	}
+
+	r, err := getRenderer(width)
+	if err != nil {
+		return src
+	}
+	out, err := r.Render(src)
+	if err != nil {
+		return src
+	}
+	for len(out) > 0 && (out[len(out)-1] == '\n' || out[len(out)-1] == ' ') {
+		out = out[:len(out)-1]
+	}
+	if len(mdCache) > 128 {
+		mdCache = map[mdCacheKey]string{}
+	}
+	mdCache[key] = out
+	return out
+}
+
+func getRenderer(width int) (*glamour.TermRenderer, error) {
+	if mdRenderer != nil && mdWidth == width {
+		return mdRenderer, nil
+	}
+	r, err := glamour.NewTermRenderer(
+		glamour.WithStyles(styles.DarkStyleConfig),
+		glamour.WithWordWrap(width),
+		glamour.WithColorProfile(termenv.ANSI256),
+		glamour.WithEmoji(),
+	)
+	if err != nil {
+		return nil, err
+	}
+	mdRenderer = r
+	mdWidth = width
+	return r, nil
+}
+
+// ClearMarkdownCache drops cached renders (e.g. after theme change).
+func ClearMarkdownCache() {
+	mdMu.Lock()
+	defer mdMu.Unlock()
+	mdCache = map[mdCacheKey]string{}
+	mdRenderer = nil
+	mdWidth = 0
+}
diff --git a/internal/ui/views/markdown_test.go b/internal/ui/views/markdown_test.go
new file mode 100644
index 0000000..7af72e6
--- /dev/null
+++ b/internal/ui/views/markdown_test.go
@@ -0,0 +1,32 @@
+package views_test
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"task/internal/ui/views"
+)
+
+func TestRenderMarkdownFastWithoutAutoStyle(t *testing.T) {
+	src := "## Hello\n\nSome **bold** text\n\n- a\n- b\n"
+	start := time.Now()
+	out := views.RenderMarkdown(src, 80)
+	elapsed := time.Since(start)
+	if elapsed > 2*time.Second {
+		t.Fatalf("RenderMarkdown took %v — WithAutoStyle/OSC hang likely still present", elapsed)
+	}
+	if out == "" || out == src {
+		// glamour should style bold; at least produce non-empty output
+		if strings.TrimSpace(out) == "" {
+			t.Fatal("empty output")
+		}
+	}
+	// cached path should be near-instant
+	start = time.Now()
+	_ = views.RenderMarkdown(src, 80)
+	if time.Since(start) > 500*time.Millisecond {
+		t.Fatalf("cached render too slow: %v", time.Since(start))
+	}
+	t.Logf("first=%v cached=%v", elapsed, time.Since(start))
+}
diff --git a/internal/ui/views/projects.go b/internal/ui/views/projects.go
new file mode 100644
index 0000000..e512820
--- /dev/null
+++ b/internal/ui/views/projects.go
@@ -0,0 +1,56 @@
+package views
+
+import (
+	"github.com/charmbracelet/bubbles/list"
+
+	"task/internal/project"
+)
+
+// ProjectItem wraps a project for bubbles/list.
+type ProjectItem struct {
+	Project project.Project
+	Active  bool
+}
+
+func (i ProjectItem) Title() string {
+	if i.Active {
+		return i.Project.Name + " *"
+	}
+	return i.Project.Name
+}
+func (i ProjectItem) Description() string { return i.Project.ID }
+func (i ProjectItem) FilterValue() string { return i.Project.Name }
+
+// NewProjectList builds a list of projects.
+func NewProjectList(projects []project.Project, activeID string, width, height int) list.Model {
+	items := make([]list.Item, len(projects))
+	selected := 0
+	for i, p := range projects {
+		items[i] = ProjectItem{Project: p, Active: p.ID == activeID}
+		if p.ID == activeID {
+			selected = i
+		}
+	}
+
+	delegate := list.NewDefaultDelegate()
+	delegate.ShowDescription = false
+	l := list.New(items, delegate, width, height)
+	l.Title = "Projects"
+	l.SetShowStatusBar(false)
+	l.SetShowHelp(false)
+	l.SetFilteringEnabled(false)
+	l.DisableQuitKeybindings()
+	if len(items) > 0 {
+		l.Select(selected)
+	}
+	return l
+}
+
+// ProjectsToItems converts projects to list items.
+func ProjectsToItems(projects []project.Project, activeID string) []list.Item {
+	items := make([]list.Item, len(projects))
+	for i, p := range projects {
+		items[i] = ProjectItem{Project: p, Active: p.ID == activeID}
+	}
+	return items
+}
diff --git a/internal/ui/views/search.go b/internal/ui/views/search.go
new file mode 100644
index 0000000..ba61b88
--- /dev/null
+++ b/internal/ui/views/search.go
@@ -0,0 +1,14 @@
+package views
+
+import (
+	"github.com/charmbracelet/bubbles/textinput"
+)
+
+// NewSearchInput returns a text input configured for search/filter.
+func NewSearchInput() textinput.Model {
+	ti := textinput.New()
+	ti.Placeholder = "Filter tasks…"
+	ti.CharLimit = 100
+	ti.Width = 60
+	return ti
+}
diff --git a/internal/ui/views/status.go b/internal/ui/views/status.go
new file mode 100644
index 0000000..3204cb8
--- /dev/null
+++ b/internal/ui/views/status.go
@@ -0,0 +1,83 @@
+package views
+
+import (
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+
+	"task/internal/ticket"
+)
+
+// StatusMenu renders a status picker overlay.
+type StatusMenu struct {
+	Cursor int
+	Width  int
+	Styles StatusMenuStyles
+}
+
+// StatusMenuStyles holds styles for the status picker.
+type StatusMenuStyles struct {
+	Box      lipgloss.Style
+	Title    lipgloss.Style
+	Selected lipgloss.Style
+	Normal   lipgloss.Style
+}
+
+// NewStatusMenu creates a menu with the given status pre-selected.
+func NewStatusMenu(current ticket.Status, width int, styles StatusMenuStyles) StatusMenu {
+	return StatusMenu{
+		Cursor: current.Index(),
+		Width:  width,
+		Styles: styles,
+	}
+}
+
+// MoveDown moves the selection down.
+func (m *StatusMenu) MoveDown() {
+	if m.Cursor < len(ticket.AllStatuses)-1 {
+		m.Cursor++
+	}
+}
+
+// MoveUp moves the selection up.
+func (m *StatusMenu) MoveUp() {
+	if m.Cursor > 0 {
+		m.Cursor--
+	}
+}
+
+// Selected returns the currently highlighted status.
+func (m StatusMenu) Selected() ticket.Status {
+	if m.Cursor < 0 || m.Cursor >= len(ticket.AllStatuses) {
+		return ticket.StatusTodo
+	}
+	return ticket.AllStatuses[m.Cursor]
+}
+
+// View renders the status menu.
+func (m StatusMenu) View() string {
+	var lines []string
+	lines = append(lines, m.Styles.Title.Render("Set status"))
+	for i, st := range ticket.AllStatuses {
+		label := "  " + st.Label()
+		if i == m.Cursor {
+			label = m.Styles.Selected.Render("▸ " + st.Label())
+		} else {
+			label = m.Styles.Normal.Render(label)
+		}
+		lines = append(lines, label)
+	}
+	body := strings.Join(lines, "\n")
+	w := m.Width
+	if w < 20 {
+		w = 20
+	}
+	return m.Styles.Box.Width(min(40, w-2)).Render(body)
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
diff --git a/internal/ui/views/tickets.go b/internal/ui/views/tickets.go
new file mode 100644
index 0000000..c3e48e5
--- /dev/null
+++ b/internal/ui/views/tickets.go
@@ -0,0 +1,243 @@
+package views
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/charmbracelet/lipgloss"
+
+	"task/internal/ticket"
+)
+
+// CollapsedCardHeight is the fixed row height for non-expanded cards
+// (single content line; left accent border adds no vertical space).
+const CollapsedCardHeight = 1
+
+// TicketListStyles holds styles for card rendering.
+type TicketListStyles struct {
+	Card         lipgloss.Style
+	CardSelected lipgloss.Style
+	StatusOPEN   lipgloss.Style
+	StatusWIP    lipgloss.Style
+	StatusDONE   lipgloss.Style
+	Headline     lipgloss.Style
+}
+
+// TicketList is a custom viewport list of ticket cards.
+type TicketList struct {
+	Items  []ticket.Ticket
+	Cursor int
+	Offset int
+	Width  int
+	Height int
+	Styles TicketListStyles
+}
+
+// SetSize updates the viewport dimensions.
+func (l *TicketList) SetSize(width, height int) {
+	l.Width = width
+	l.Height = height
+	l.ensureVisible()
+}
+
+// SetItems replaces the ticket list, clamping the cursor.
+func (l *TicketList) SetItems(items []ticket.Ticket) {
+	l.Items = items
+	if l.Cursor >= len(l.Items) {
+		l.Cursor = max(0, len(l.Items)-1)
+	}
+	l.Offset = 0
+	l.ensureVisible()
+}
+
+// Selected returns the currently selected ticket and whether one exists.
+func (l *TicketList) Selected() (ticket.Ticket, bool) {
+	if len(l.Items) == 0 || l.Cursor < 0 || l.Cursor >= len(l.Items) {
+		return ticket.Ticket{}, false
+	}
+	return l.Items[l.Cursor], true
+}
+
+// CursorIndex returns the current cursor.
+func (l *TicketList) CursorIndex() int { return l.Cursor }
+
+// Len returns the number of tickets.
+func (l *TicketList) Len() int { return len(l.Items) }
+
+// MoveDown moves the cursor down.
+func (l *TicketList) MoveDown() {
+	if l.Cursor < len(l.Items)-1 {
+		l.Cursor++
+		l.ensureVisible()
+	}
+}
+
+// MoveUp moves the cursor up.
+func (l *TicketList) MoveUp() {
+	if l.Cursor > 0 {
+		l.Cursor--
+		l.ensureVisible()
+	}
+}
+
+// Select sets the cursor to idx if in range.
+func (l *TicketList) Select(idx int) {
+	if idx < 0 || idx >= len(l.Items) {
+		return
+	}
+	l.Cursor = idx
+	l.ensureVisible()
+}
+
+// View renders only the visible ticket cards.
+func (l *TicketList) View() string {
+	if l.Height < 1 {
+		return ""
+	}
+	if len(l.Items) == 0 {
+		empty := lipgloss.NewStyle().Faint(true).Render("No tickets — press n to create one")
+		return lipgloss.NewStyle().Width(l.Width).Height(l.Height).Render(empty)
+	}
+
+	var visible []string
+	used := 0
+	for i := l.Offset; i < len(l.Items); i++ {
+		card := l.renderCard(l.Items[i], i == l.Cursor)
+		h := lipgloss.Height(card)
+		if used > 0 && used+h > l.Height {
+			break
+		}
+		visible = append(visible, card)
+		used += h
+	}
+
+	body := lipgloss.JoinVertical(lipgloss.Left, visible...)
+	return lipgloss.NewStyle().Width(l.Width).Height(l.Height).MaxHeight(l.Height).Render(body)
+}
+
+func (l *TicketList) renderCard(t ticket.Ticket, selected bool) string {
+	innerWidth := max(10, l.Width-4)
+
+	badge := l.statusBadge(t.Status)
+	headline := truncateOneLine(plainHeadline(t.Title), max(8, innerWidth-lipgloss.Width(badge)-2))
+	headerLine := badge + " " + l.Styles.Headline.Render(headline)
+
+	var content string
+	if selected {
+		// Expanded: headline + glamour-rendered description (fixed dark style).
+		desc := strings.TrimSpace(t.Description)
+		if desc != "" {
+			content = headerLine + "\n" + RenderMarkdown(desc, innerWidth)
+		} else {
+			content = headerLine
+		}
+	} else {
+		content = headerLine
+	}
+
+	style := l.Styles.Card
+	if selected {
+		style = l.Styles.CardSelected
+	}
+	return style.Width(max(4, l.Width-2)).Render(content)
+}
+
+func (l *TicketList) statusBadge(s ticket.Status) string {
+	label := fmt.Sprintf(" %s ", s.Label())
+	switch s {
+	case ticket.StatusInProgress:
+		return l.Styles.StatusWIP.Render(label)
+	case ticket.StatusDone:
+		return l.Styles.StatusDONE.Render(label)
+	default:
+		return l.Styles.StatusOPEN.Render(label)
+	}
+}
+
+func (l *TicketList) ensureVisible() {
+	if len(l.Items) == 0 {
+		l.Offset = 0
+		return
+	}
+	if l.Cursor < l.Offset {
+		l.Offset = l.Cursor
+		return
+	}
+
+	for {
+		used := 0
+		fits := false
+		for i := l.Offset; i < len(l.Items); i++ {
+			h := l.estimateHeight(i)
+			if used > 0 && used+h > l.Height {
+				break
+			}
+			used += h
+			if i == l.Cursor {
+				fits = true
+				break
+			}
+		}
+		if fits || l.Offset >= l.Cursor {
+			break
+		}
+		l.Offset++
+	}
+}
+
+// estimateHeight avoids full glamour for collapsed cards.
+func (l *TicketList) estimateHeight(index int) int {
+	if index < 0 || index >= len(l.Items) {
+		return CollapsedCardHeight
+	}
+	if index == l.Cursor && strings.TrimSpace(l.Items[index].Description) != "" {
+		return lipgloss.Height(l.renderCard(l.Items[index], true))
+	}
+	return CollapsedCardHeight
+}
+
+// FilterTickets returns tickets matching query in title or description.
+func FilterTickets(tickets []ticket.Ticket, query string) []ticket.Ticket {
+	q := strings.ToLower(strings.TrimSpace(query))
+	if q == "" {
+		return tickets
+	}
+	var out []ticket.Ticket
+	for _, t := range tickets {
+		if strings.Contains(strings.ToLower(t.Title), q) ||
+			strings.Contains(strings.ToLower(t.Description), q) {
+			out = append(out, t)
+		}
+	}
+	return out
+}
+
+func plainHeadline(title string) string {
+	title = strings.TrimSpace(title)
+	title = strings.TrimLeft(title, "#")
+	return strings.TrimSpace(title)
+}
+
+func truncateOneLine(s string, maxWidth int) string {
+	if maxWidth <= 0 {
+		return ""
+	}
+	if lipgloss.Width(s) <= maxWidth {
+		return s
+	}
+	runes := []rune(s)
+	for len(runes) > 0 {
+		runes = runes[:len(runes)-1]
+		if lipgloss.Width(string(runes)) <= maxWidth-1 {
+			return string(runes) + "…"
+		}
+	}
+	return ""
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
diff --git a/internal/version/version.go b/internal/version/version.go
new file mode 100644
index 0000000..c42ed0b
--- /dev/null
+++ b/internal/version/version.go
@@ -0,0 +1,5 @@
+package version
+
+// BuildVersion is set at link time via -ldflags.
+// Default "dev" for go run / IDE builds without Makefile.
+var BuildVersion = "dev"