Item annotations and async methods (#4)

- New UCL method for setting up item annotations
- New UCL package for running commands asynchronously

Reviewed-on: #4
Co-authored-by: Leon Mika <lmika@lmika.org>
Co-committed-by: Leon Mika <lmika@lmika.org>

internal/common/ui/commandctrl/cmdpacks/modasync.go

@@ -0,0 +1,96 @@
+package cmdpacks
+
+import (
+	"context"
+	"time"
+
+	"github.com/go-co-op/gocron/v2"
+	"lmika.dev/cmd/dynamo-browse/internal/common/ui/commandctrl"
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/controllers"
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/services/tables"
+	"ucl.lmika.dev/ucl"
+)
+
+type asyncModule struct {
+	tableService *tables.Service
+	state        *controllers.State
+}
+
+func (m asyncModule) asyncDo(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var block ucl.Invokable
+	if err := args.Bind(&block); err != nil {
+		return nil, err
+	}
+
+	return nil, commandctrl.ScheduleTask(ctx, func(ctx context.Context) error {
+		_, err := block.Invoke(ctx)
+		return err
+	})
+}
+
+func (m asyncModule) asyncIn(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var (
+		duration int
+		block    ucl.Invokable
+	)
+	if err := args.Bind(&duration, &block); err != nil {
+		return nil, err
+	}
+
+	_, err := commandctrl.CronScheduler(ctx).NewJob(
+		gocron.OneTimeJob(
+			gocron.OneTimeJobStartDateTime(time.Now().Add(time.Duration(duration)*time.Second)),
+		),
+		gocron.NewTask(func(ctx context.Context) {
+			commandctrl.ScheduleTask(ctx, func(ctx context.Context) error {
+				_, err := block.Invoke(ctx)
+				return err
+			})
+		}),
+		gocron.WithContext(ctx),
+	)
+	return nil, err
+}
+
+func (m asyncModule) asyncQuery(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var (
+		block ucl.Invokable
+	)
+
+	args, q, tableInfo, err := parseQuery(ctx, args, m.state.ResultSet(), m.tableService, 1)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := args.Bind(&block); err != nil {
+		return nil, err
+	}
+
+	return nil, commandctrl.ScheduleAuxTask(ctx, "query: "+q.String(), func(ctx context.Context) error {
+		newResultSet, err := m.tableService.ScanOrQuery(context.Background(), tableInfo, q, nil)
+		if err != nil {
+			return err
+		}
+
+		return commandctrl.ScheduleTask(ctx, func(ctx context.Context) error {
+			_, err := block.Invoke(ctx, newResultSetProxy(newResultSet))
+			return err
+		})
+	})
+}
+
+func moduleAsync(tableService *tables.Service, state *controllers.State) ucl.Module {
+	m := asyncModule{
+		state:        state,
+		tableService: tableService,
+	}
+
+	return ucl.Module{
+		Name: "async",
+		Builtins: map[string]ucl.BuiltinHandler{
+			"do":    m.asyncDo,
+			"in":    m.asyncIn,
+			"query": m.asyncQuery,
+		},
+	}
+}

internal/common/ui/commandctrl/cmdpacks/modav.go

@@ -2,6 +2,7 @@ package cmdpacks
 
 import (
 	"context"
+
 	"github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
 	"ucl.lmika.dev/ucl"
 )

internal/common/ui/commandctrl/cmdpacks/modrs.go

@@ -2,6 +2,8 @@ package cmdpacks
 
 import (
 	"context"
+	"time"
+
 	"github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
 	"github.com/pkg/errors"
 	"lmika.dev/cmd/dynamo-browse/internal/common/ui/commandctrl"
@@ -9,7 +11,6 @@ import (
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models/queryexpr"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/services/tables"
-	"time"
 	"ucl.lmika.dev/repl"
 	"ucl.lmika.dev/ucl"
 )
@@ -71,21 +72,22 @@ func parseQuery(
 	args ucl.CallArgs,
 	currentRS *models.ResultSet,
 	tablesService *tables.Service,
-) (*queryexpr.QueryExpr, *models.TableInfo, error) {
+	extraArgs int,
+) (ucl.CallArgs, *queryexpr.QueryExpr, *models.TableInfo, error) {
 	var expr string
 	if err := args.Bind(&expr); err != nil {
-		return nil, nil, err
+		return args, nil, nil, err
 	}
 
 	q, err := queryexpr.Parse(expr)
 	if err != nil {
-		return nil, nil, err
+		return args, nil, nil, err
 	}
 
-	if args.NArgs() > 0 {
+	if args.NArgs() > extraArgs {
 		var queryArgs ucl.Hashable
 		if err := args.Bind(&queryArgs); err != nil {
-			return nil, nil, err
+			return args, nil, nil, err
 		}
 
 		queryNames := map[string]string{}
@@ -97,12 +99,15 @@ func parseQuery(
 
 			queryNames[k] = v.String()
 
-			switch v.(type) {
+			switch t := v.(type) {
 			case ucl.StringObject:
 				queryValues[k] = &types.AttributeValueMemberS{Value: v.String()}
 			case ucl.IntObject:
 				queryValues[k] = &types.AttributeValueMemberN{Value: v.String()}
-				// TODO: other types
+			case ucl.BoolObject:
+				queryValues[k] = &types.AttributeValueMemberBOOL{Value: t.Truthy()}
+			case attributeValueProxy:
+				queryValues[k] = t.value
 			}
 			return nil
 		})
@@ -114,24 +119,24 @@ func parseQuery(
 	if args.HasSwitch("table") {
 		var tblName string
 		if err := args.BindSwitch("table", &tblName); err != nil {
-			return nil, nil, err
+			return args, nil, nil, err
 		}
 
 		tableInfo, err = tablesService.Describe(ctx, tblName)
 		if err != nil {
-			return nil, nil, err
+			return args, nil, nil, err
 		}
 	} else if currentRS != nil && currentRS.TableInfo != nil {
 		tableInfo = currentRS.TableInfo
 	} else {
-		return nil, nil, errors.New("no table specified")
+		return args, nil, nil, errors.New("no table specified")
 	}
 
-	return q, tableInfo, nil
+	return args, q, tableInfo, nil
 }
 
 func (rs *rsModule) rsQuery(ctx context.Context, args ucl.CallArgs) (any, error) {
-	q, tableInfo, err := parseQuery(ctx, args, rs.state.ResultSet(), rs.tableService)
+	_, q, tableInfo, err := parseQuery(ctx, args, rs.state.ResultSet(), rs.tableService, 0)
 	if err != nil {
 		return nil, err
 	}

internal/common/ui/commandctrl/cmdpacks/modrs_test.go

@@ -214,6 +214,14 @@ func TestModRS_First(t *testing.T) {
 				rs = rs:query 'pk="zzz"' -table service-test-data
 				assert (eq $rs.First ()) "expected First to be nil"
 			`,
+		}, {
+			descr: "returns the first item using placeholders",
+			cmd: `
+				rs = rs:query 'pk=$v and sk=$u' [v:"abc" u:"222"] -table service-test-data
+				assert (eq $rs.First.pk "abc") "expected First.pk == abc"
+				assert (eq $rs.First.sk "222") "expected First.sk == 222"
+				assert (eq $rs.First.beta 1231) "expected First.beta == 1231"
+			`,
 		},
 	}
 	for _, tt := range tests {

internal/common/ui/commandctrl/cmdpacks/modui.go

@@ -2,11 +2,14 @@ package cmdpacks
 
 import (
 	"context"
+	"fmt"
 
 	tea "github.com/charmbracelet/bubbletea"
 	"lmika.dev/cmd/dynamo-browse/internal/common/ui/commandctrl"
 	"lmika.dev/cmd/dynamo-browse/internal/common/ui/events"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/controllers"
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models"
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/services/itemrenderer"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/services/tables"
 	"ucl.lmika.dev/ucl"
 )
@@ -16,6 +19,7 @@ type uiModule struct {
 	state          *controllers.State
 	ckb            *customKeyBinding
 	readController *controllers.TableReadController
+	itemRenderer   *itemrenderer.Service
 }
 
 func (m *uiModule) uiCommand(ctx context.Context, args ucl.CallArgs) (any, error) {
@@ -171,7 +175,7 @@ func (m *uiModule) uiBind(ctx context.Context, args ucl.CallArgs) (any, error) {
 }
 
 func (m *uiModule) uiQuery(ctx context.Context, args ucl.CallArgs) (any, error) {
-	q, tableInfo, err := parseQuery(ctx, args, m.state.ResultSet(), m.tableService)
+	_, q, tableInfo, err := parseQuery(ctx, args, m.state.ResultSet(), m.tableService, 0)
 	if err != nil {
 		return nil, err
 	}
@@ -191,15 +195,36 @@ func (m *uiModule) uiFilter(ctx context.Context, args ucl.CallArgs) (any, error)
 	return nil, nil
 }
 
+func (m *uiModule) uiSetItemAnnotator(ctx context.Context, args ucl.CallArgs) (any, error) {
+	var inv ucl.Invokable
+	if err := args.Bind(&inv); err != nil {
+		return nil, err
+	}
+
+	m.itemRenderer.SetAnnotation(itemrenderer.AnnotationFunc(func(rs *models.ResultSet, item models.Item, path models.AttrPathNode) string {
+		v, err := inv.Invoke(ctx, newResultSetProxy(rs), itemProxy{rs, 0, item}, attrPathProxy{attrPath: &path})
+		if err != nil {
+			return ""
+		} else if v == nil {
+			return ""
+		}
+		return fmt.Sprint(v)
+	}))
+	commandctrl.QueueRefresh(ctx)
+	return nil, nil
+}
+
 func moduleUI(
 	tableService *tables.Service,
 	state *controllers.State,
 	readController *controllers.TableReadController,
+	itemRenderer *itemrenderer.Service,
 ) (ucl.Module, controllers.CustomKeyBindingSource) {
 	m := &uiModule{
 		tableService:   tableService,
 		state:          state,
 		readController: readController,
+		itemRenderer:   itemRenderer,
 		ckb: &customKeyBinding{
 			bindings:    map[string]tea.Cmd{},
 			keyBindings: map[string]string{},
@@ -209,14 +234,15 @@ func moduleUI(
 	return ucl.Module{
 		Name: "ui",
 		Builtins: map[string]ucl.BuiltinHandler{
-			"command":         m.uiCommand,
-			"prompt":          m.uiPrompt,
-			"prompt-table":    m.uiPromptTable,
-			"prompt-keypress": m.uiInKey,
-			"confirm":         m.uiConfirm,
-			"query":           m.uiQuery,
-			"filter":          m.uiFilter,
-			"bind":            m.uiBind,
+			"command":            m.uiCommand,
+			"prompt":             m.uiPrompt,
+			"prompt-table":       m.uiPromptTable,
+			"prompt-keypress":    m.uiInKey,
+			"confirm":            m.uiConfirm,
+			"query":              m.uiQuery,
+			"filter":             m.uiFilter,
+			"bind":               m.uiBind,
+			"set-item-annotator": m.uiSetItemAnnotator,
 		},
 	}, m.ckb
 }

internal/common/ui/commandctrl/cmdpacks/proxy.go

@@ -234,6 +234,49 @@ func (tp itemProxy) Each(fn func(k string, v ucl.Object) error) error {
 	return nil
 }
 
+type attrPathProxy struct {
+	attrPath *models.AttrPathNode
+}
+
+func (ap attrPathProxy) String() string {
+	return "RSItem()"
+}
+
+func (ap attrPathProxy) Truthy() bool {
+	return true
+}
+
+func (ap attrPathProxy) Len() (l int) {
+	for p := ap.attrPath; p != nil; p = p.Parent {
+		l++
+	}
+	return
+}
+
+func (ap attrPathProxy) Index(k int) ucl.Object {
+	if k == -1 {
+		return ucl.StringObject(ap.attrPath.Key)
+	}
+
+	if k >= 0 {
+		k = ap.Len() - k - 1
+	} else {
+		k = -k - 1
+	}
+
+	if k < 0 {
+		return nil
+	}
+	for p := ap.attrPath; p != nil; p = p.Parent {
+		if k <= 0 {
+			return ucl.StringObject(p.Key)
+		}
+		k -= 1
+	}
+
+	return nil
+}
+
 type attributeValueProxy struct {
 	value types.AttributeValue
 }

internal/common/ui/commandctrl/cmdpacks/proxy_test.go

@@ -0,0 +1,101 @@
+package cmdpacks
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models"
+)
+
+func TestAttrPathProxy_Index(t *testing.T) {
+	tests := []struct {
+		descr    string
+		attrPath models.AttrPathNode
+		index    int
+		want     string
+		wantNil  bool
+	}{
+		{
+			descr:    "return leaf 1",
+			attrPath: models.AttrPathNode{Key: "leaf"},
+			index:    -1,
+			want:     "leaf",
+		},
+		{
+			descr:    "return leaf 2",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent"}},
+			index:    -1,
+			want:     "leaf",
+		},
+		{
+			descr:    "return parent 1",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent"}},
+			index:    -2,
+			want:     "parent",
+		},
+		{
+			descr:    "return parent 1",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent", Parent: &models.AttrPathNode{Key: "grandparent"}}},
+			index:    -2,
+			want:     "parent",
+		},
+		{
+			descr:    "return parent 3",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent", Parent: &models.AttrPathNode{Key: "grandparent"}}},
+			index:    -3,
+			want:     "grandparent",
+		},
+		{
+			descr:    "return root 1",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent", Parent: &models.AttrPathNode{Key: "grandparent"}}},
+			index:    0,
+			want:     "grandparent",
+		},
+		{
+			descr:    "return root 2",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent"}},
+			index:    0,
+			want:     "parent",
+		},
+		{
+			descr:    "return root 3",
+			attrPath: models.AttrPathNode{Key: "leaf"},
+			index:    0,
+			want:     "leaf",
+		},
+		{
+			descr:    "return first child 1",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent", Parent: &models.AttrPathNode{Key: "grandparent"}}},
+			index:    1,
+			want:     "parent",
+		},
+		{
+			descr:    "return first child 2",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent"}},
+			index:    1,
+			want:     "leaf",
+		},
+		{
+			descr:    "return nil 1",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent", Parent: &models.AttrPathNode{Key: "grandparent"}}},
+			index:    -5,
+			wantNil:  true,
+		},
+		{
+			descr:    "return nil 2",
+			attrPath: models.AttrPathNode{Key: "leaf", Parent: &models.AttrPathNode{Key: "parent"}},
+			index:    56,
+			wantNil:  true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.descr, func(t *testing.T) {
+			proxy := attrPathProxy{&tt.attrPath}
+			if tt.wantNil {
+				assert.Nil(t, proxy.Index(tt.index))
+			} else {
+				assert.Equal(t, tt.want, proxy.Index(tt.index).String())
+			}
+		})
+	}
+}

internal/common/ui/commandctrl/cmdpacks/stdcmds.go

@@ -9,6 +9,7 @@ import (
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/controllers"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/services"
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/services/itemrenderer"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/services/tables"
 	"ucl.lmika.dev/repl"
 	"ucl.lmika.dev/ucl"
@@ -23,6 +24,7 @@ type StandardCommands struct {
 	KeyBindingController *controllers.KeyBindingController
 	PBProvider           services.PasteboardProvider
 	SettingsController   *controllers.SettingsController
+	ItemRenderer         *itemrenderer.Service
 
 	modUI ucl.Module
 }
@@ -36,8 +38,9 @@ func NewStandardCommands(
 	keyBindingController *controllers.KeyBindingController,
 	pbProvider services.PasteboardProvider,
 	settingsController *controllers.SettingsController,
+	itemRenderer *itemrenderer.Service,
 ) StandardCommands {
-	modUI, ckbs := moduleUI(tableService, state, readController)
+	modUI, ckbs := moduleUI(tableService, state, readController, itemRenderer)
 	keyBindingController.SetCustomKeyBindingSource(ckbs)
 
 	return StandardCommands{
@@ -49,6 +52,7 @@ func NewStandardCommands(
 		KeyBindingController: keyBindingController,
 		PBProvider:           pbProvider,
 		SettingsController:   settingsController,
+		ItemRenderer:         itemRenderer,
 		modUI:                modUI,
 	}
 }
@@ -400,6 +404,7 @@ func (sc StandardCommands) InstOptions() []ucl.InstOption {
 		ucl.WithModule(modulePB(sc.PBProvider)),
 		ucl.WithModule(moduleOpt(sc.SettingsController)),
 		ucl.WithModule(moduleAttrValue()),
+		ucl.WithModule(moduleAsync(sc.TableService, sc.State)),
 	}
 }
 

internal/common/ui/commandctrl/cmdpacks/stdcmds_test.go

@@ -2,6 +2,8 @@ package cmdpacks_test
 
 import (
 	"fmt"
+	"testing"
+
 	tea "github.com/charmbracelet/bubbletea"
 	bus "github.com/lmika/events"
 	"github.com/stretchr/testify/assert"
@@ -21,7 +23,6 @@ import (
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/ui/keybindings"
 	"lmika.dev/cmd/dynamo-browse/test/testdynamo"
 	"lmika.dev/cmd/dynamo-browse/test/testworkspace"
-	"testing"
 )
 
 func TestStdCmds_Mark(t *testing.T) {
@@ -162,6 +163,7 @@ func newService(t *testing.T, opts ...serviceOpt) *services {
 			keyBindingController,
 			testPB,
 			settingsController,
+			itemRendererService,
 		),
 	)
 

internal/common/ui/commandctrl/commandctrl.go

@@ -4,12 +4,14 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	tea "github.com/charmbracelet/bubbletea"
-	"github.com/pkg/errors"
 	"log"
 	"os"
 	"path/filepath"
 	"strings"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/go-co-op/gocron/v2"
+	"github.com/pkg/errors"
 	"ucl.lmika.dev/ucl"
 	"ucl.lmika.dev/ucl/builtins"
 
@@ -17,12 +19,22 @@ import (
 	"lmika.dev/cmd/dynamo-browse/internal/common/ui/events"
 )
 
-const commandsCategory = "commands"
+const (
+	commandsCategory     = "commands"
+	pendingTaskBuffer    = 50
+	pendingAuxTaskBuffer = 50
+	auxWorkers           = 4
+)
 
 type cmdMessage struct {
 	cmd string
 }
 
+type pendingTask struct {
+	descr string
+	task  func(ctx context.Context) error
+}
+
 type CommandController struct {
 	uclInst            *ucl.Inst
 	historyProvider    IterProvider
@@ -30,19 +42,29 @@ type CommandController struct {
 	lookupExtensions   []CommandLookupExtension
 	completionProvider CommandCompletionProvider
 	uiStateProvider    UIStateProvider
+	cronScheduler      gocron.Scheduler
 	cmdChan            chan cmdMessage
+	pendingTaskChan    chan pendingTask
+	pendingAuxTaskChan chan pendingTask
 	msgChan            chan tea.Msg
 	interactive        bool
 }
 
 func NewCommandController(historyProvider IterProvider, pkgs ...CommandPack) (*CommandController, error) {
+	sched, err := gocron.NewScheduler()
+	if err != nil {
+		return nil, err
+	}
 	cc := &CommandController{
-		historyProvider:  historyProvider,
-		commandList:      nil,
-		lookupExtensions: nil,
-		cmdChan:          make(chan cmdMessage),
-		msgChan:          make(chan tea.Msg),
-		interactive:      true,
+		historyProvider:    historyProvider,
+		commandList:        nil,
+		lookupExtensions:   nil,
+		cronScheduler:      sched,
+		cmdChan:            make(chan cmdMessage),
+		pendingTaskChan:    make(chan pendingTask, pendingTaskBuffer),
+		pendingAuxTaskChan: make(chan pendingTask, pendingAuxTaskBuffer),
+		msgChan:            make(chan tea.Msg),
+		interactive:        true,
 	}
 
 	options := []ucl.InstOption{
@@ -75,6 +97,8 @@ func NewCommandController(historyProvider IterProvider, pkgs ...CommandPack) (*C
 	}
 
 	go cc.cmdLooper()
+	go cc.auxCmdLooper()
+	sched.Start()
 
 	return cc, nil
 }
@@ -172,12 +196,13 @@ func (c *CommandController) Invoke(invokable ucl.Invokable, args []any) (msg tea
 }
 
 func (c *CommandController) cmdLooper() {
-	execCtx := execContext{ctrl: c}
-	ctx := context.WithValue(context.Background(), commandCtlKey, &execCtx)
-
+	ctx := context.Background()
 	for {
 		select {
 		case cmdChan := <-c.cmdChan:
+			execCtx := execContext{ctrl: c}
+			ctx := context.WithValue(ctx, commandCtlKey, &execCtx)
+
 			res, err := c.ExecuteAndWait(ctx, cmdChan.cmd)
 			if err != nil {
 				c.postMessage(events.Error(err))
@@ -187,6 +212,16 @@ func (c *CommandController) cmdLooper() {
 			if execCtx.requestRefresh {
 				c.postMessage(events.ResultSetUpdated{})
 			}
+		case task := <-c.pendingTaskChan:
+			execCtx := execContext{ctrl: c}
+			ctx := context.WithValue(ctx, commandCtlKey, &execCtx)
+
+			if err := task.task(ctx); err != nil {
+				c.postMessage(events.Error(err))
+			}
+			if execCtx.requestRefresh {
+				c.postMessage(events.ResultSetUpdated{})
+			}
 		}
 	}
 }
@@ -305,15 +340,13 @@ func (c *CommandController) cmdInvoker(ctx context.Context, name string, args uc
 }
 
 func (c *CommandController) printLine(s string) {
+	log.Println(s)
 	if c.msgChan == nil || !c.interactive {
-		log.Println(s)
 		return
 	}
 
 	select {
 	case c.msgChan <- events.StatusMsg(s):
-	default:
-		log.Println(s)
 	}
 }
 
@@ -325,6 +358,21 @@ func (c *CommandController) postMessage(msg tea.Msg) {
 	c.msgChan <- msg
 }
 
+func (c *CommandController) auxCmdLooper() {
+	ctx := context.WithValue(context.Background(), commandCtlKey, &execContext{ctrl: c})
+
+	for i := 0; i < auxWorkers; i++ {
+		go func() {
+			for auxTask := range c.pendingAuxTaskChan {
+				log.Printf("running aux task: %v", auxTask.descr)
+				if err := auxTask.task(ctx); err != nil {
+					log.Printf("aux task error: %v", err)
+				}
+			}
+		}()
+	}
+}
+
 type teaMsgWrapper struct {
 	msg tea.Msg
 }

internal/common/ui/commandctrl/ctx.go

@@ -2,7 +2,10 @@ package commandctrl
 
 import (
 	"context"
+
 	tea "github.com/charmbracelet/bubbletea"
+	"github.com/go-co-op/gocron/v2"
+	"github.com/pkg/errors"
 	"ucl.lmika.dev/ucl"
 )
 
@@ -57,6 +60,40 @@ func QueueRefresh(ctx context.Context) {
 	cmdCtl.requestRefresh = true
 }
 
+func CronScheduler(ctx context.Context) gocron.Scheduler {
+	cmdCtl, ok := ctx.Value(commandCtlKey).(*execContext)
+	if !ok {
+		return nil
+	}
+	return cmdCtl.ctrl.cronScheduler
+}
+
+func ScheduleTask(ctx context.Context, task func(ctx context.Context) error) error {
+	cmdCtl, ok := ctx.Value(commandCtlKey).(*execContext)
+	if !ok {
+		return errors.New("no command controller")
+	}
+	select {
+	case cmdCtl.ctrl.pendingTaskChan <- pendingTask{task: task}:
+		return nil
+	default:
+		return errors.New("task queue is full")
+	}
+}
+
+func ScheduleAuxTask(ctx context.Context, descr string, task func(ctx context.Context) error) error {
+	cmdCtl, ok := ctx.Value(commandCtlKey).(*execContext)
+	if !ok {
+		return errors.New("no command controller")
+	}
+	select {
+	case cmdCtl.ctrl.pendingAuxTaskChan <- pendingTask{descr: descr, task: task}:
+		return nil
+	default:
+		return errors.New("aux task queue is full")
+	}
+}
+
 type Invoker interface {
 	Invoke(invokable ucl.Invokable, args []any) tea.Msg
 	Inst() *ucl.Inst

internal/dynamo-browse/models/attrpath.go

@@ -0,0 +1,6 @@
+package models
+
+type AttrPathNode struct {
+	Key    string
+	Parent *AttrPathNode
+}

internal/dynamo-browse/services/itemrenderer/service.go

@@ -2,18 +2,30 @@ package itemrenderer
 
 import (
 	"fmt"
-	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models"
-	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models/itemrender"
 	"io"
 	"text/tabwriter"
+
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models"
+	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/models/itemrender"
 )
 
 type Service struct {
-	styles styleRenderer
+	annotation Annotation
+	styles     styleRenderer
 }
 
-func NewService(fileTypeStyle StyleRenderer, metaInfoStyle StyleRenderer) *Service {
+func NewService(
+	fileTypeStyle StyleRenderer,
+	metaInfoStyle StyleRenderer,
+) *Service {
+	if fileTypeStyle == nil {
+		fileTypeStyle = plainTextStyleRenderer{}
+	}
+	if metaInfoStyle == nil {
+		metaInfoStyle = plainTextStyleRenderer{}
+	}
 	return &Service{
+		annotation: nil,
 		styles: styleRenderer{
 			fileTypeRenderer: fileTypeStyle,
 			metaInfoRenderer: metaInfoStyle,
@@ -21,6 +33,10 @@ func NewService(fileTypeStyle StyleRenderer, metaInfoStyle StyleRenderer) *Servi
 	}
 }
 
+func (s *Service) SetAnnotation(a Annotation) {
+	s.annotation = a
+}
+
 func (s *Service) RenderItem(w io.Writer, item models.Item, resultSet *models.ResultSet, plainText bool) {
 	styles := s.styles
 	if plainText {
@@ -33,25 +49,47 @@ func (s *Service) RenderItem(w io.Writer, item models.Item, resultSet *models.Re
 	for _, colName := range resultSet.Columns() {
 		seenColumns[colName] = struct{}{}
 		if r := itemrender.ToRenderer(item[colName]); r != nil {
-			s.renderItem(tabWriter, "", colName, r, styles)
+			p := models.AttrPathNode{Key: colName}
+			s.renderItem(tabWriter, resultSet, item, p, "", r, styles)
 		}
 	}
 	for k, _ := range item {
 		if _, seen := seenColumns[k]; !seen {
 			if r := itemrender.ToRenderer(item[k]); r != nil {
-				s.renderItem(tabWriter, "", k, r, styles)
+				p := models.AttrPathNode{Key: k}
+				s.renderItem(tabWriter, resultSet, item, p, "", r, styles)
 			}
 		}
 	}
 	tabWriter.Flush()
 }
 
-func (m *Service) renderItem(w io.Writer, prefix string, name string, r itemrender.Renderer, sr styleRenderer) {
-	fmt.Fprintf(w, "%s%v\t%s\t%s%s\n",
-		prefix, name, sr.fileTypeRenderer.Render(r.TypeName()), r.StringValue(), sr.metaInfoRenderer.Render(r.MetaInfo()))
+func (m *Service) renderItem(
+	w io.Writer,
+	resultSet *models.ResultSet,
+	item models.Item,
+	path models.AttrPathNode,
+	prefix string,
+	r itemrender.Renderer,
+	sr styleRenderer,
+) {
+	fmt.Fprint(w, prefix)
+	fmt.Fprint(w, path.Key)
+	fmt.Fprint(w, "\t")
+	fmt.Fprint(w, sr.fileTypeRenderer.Render(r.TypeName()))
+	fmt.Fprint(w, "\t")
+	fmt.Fprint(w, r.StringValue())
+	fmt.Fprint(w, sr.metaInfoRenderer.Render(r.MetaInfo()))
+	if m.annotation != nil {
+		fmt.Fprint(w, "  ")
+		fmt.Fprint(w, sr.metaInfoRenderer.Render(m.annotation.AnnotateAttribute(resultSet, item, path)))
+	}
+	fmt.Fprint(w, "\n")
+
 	if subitems := r.SubItems(); len(subitems) > 0 {
 		for _, si := range subitems {
-			m.renderItem(w, prefix+"  ", si.Key, si.Value, sr)
+			p := models.AttrPathNode{Key: si.Key, Parent: &path}
+			m.renderItem(w, resultSet, item, p, prefix+"  ", si.Value, sr)
 		}
 	}
 }
@@ -60,3 +98,13 @@ type styleRenderer struct {
 	fileTypeRenderer StyleRenderer
 	metaInfoRenderer StyleRenderer
 }
+
+type Annotation interface {
+	AnnotateAttribute(rs *models.ResultSet, item models.Item, path models.AttrPathNode) string
+}
+
+type AnnotationFunc func(rs *models.ResultSet, item models.Item, path models.AttrPathNode) string
+
+func (af AnnotationFunc) AnnotateAttribute(rs *models.ResultSet, item models.Item, path models.AttrPathNode) string {
+	return af(rs, item, path)
+}

internal/dynamo-browse/ui/teamodels/dynamoitemview/model.go

@@ -1,6 +1,8 @@
 package dynamoitemview
 
 import (
+	"strings"
+
 	"github.com/charmbracelet/bubbles/viewport"
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
@@ -9,7 +11,6 @@ import (
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/ui/teamodels/frame"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/ui/teamodels/layout"
 	"lmika.dev/cmd/dynamo-browse/internal/dynamo-browse/ui/teamodels/styles"
-	"strings"
 )
 
 type Model struct {

internal/dynamo-browse/ui/teamodels/styles/styles.go

@@ -20,7 +20,7 @@ type ItemViewStyle struct {
 var DefaultStyles = Styles{
 	ItemView: ItemViewStyle{
 		FieldType: lipgloss.NewStyle().Foreground(lipgloss.AdaptiveColor{Light: "#2B800C", Dark: "#73C653"}),
-		MetaInfo:  lipgloss.NewStyle().Foreground(lipgloss.Color("#888888")),
+		MetaInfo:  lipgloss.NewStyle().Foreground(lipgloss.Color("#707070")),
 	},
 	Frames: frame.Style{
 		ActiveTitle: lipgloss.NewStyle().