NOM Progress

What is NOM?

NOM (Nix Output Monitor) style progress visualization tracks long-running workflows with dependency trees, activity counts, and timing estimates. It’s inspired by nix-output-monitor.

Static Rendering (One-Shot)

Build state, take a snapshot, render once — useful for logs, CI output, or testing:

import (
    "context"
    "fmt"
    "time"

    "github.com/larsartmann/go-output/nom"
)

ctx := context.Background()
sub := nom.NewNOMSubscriber()

sub.OnEvent(ctx, nom.WorkflowStarted{
    ID:   nom.NewWorkflowID("build"),
    Name: nom.NewWorkflowName("Build Project"),
})
sub.OnEvent(ctx, nom.ActivityStarted{
    ID:   nom.NewActivityID("compile"),
    Name: nom.NewActivityName("Compile"),
})
sub.OnEvent(ctx, nom.ActivityStarted{
    ID:   nom.NewActivityID("test"),
    Name: nom.NewActivityName("Run Tests"),
    Deps: []nom.ActivityID{nom.NewActivityID("compile")},
})
sub.OnEvent(ctx, nom.ActivityCompleted{
    ID:       nom.NewActivityID("compile"),
    Name:     nom.NewActivityName("Compile"),
    Duration: 5 * time.Second,
})

// Render a snapshot
snaps := sub.SnapshotActivities()
fmt.Println(sub.DependencyTree().RenderWithSnapshots(snaps, 20, 0))

// O(1) summary counts
counts := sub.GetActivityCounts()
fmt.Printf("Running: %d, Completed: %d, Failed: %d\n",
    counts.Running, counts.Completed, counts.Failed)

sub.OnEvent(ctx, nom.WorkflowCompleted{ID: nom.NewWorkflowID("build")})

Live Inline Rendering (Terminal)

For real-time updates, the InlineRenderer redraws the tree in-place using ANSI escape codes:

sub := nom.NewNOMSubscriber()
renderer := nom.NewInlineRenderer(sub, os.Stdout, 20) // maxHeight 20 lines

ctx := context.Background()
renderer.Start(ctx, 100*time.Millisecond) // redraw every 100ms
defer renderer.Finish(nil)

// In your workers (goroutines):
sub.OnEvent(ctx, nom.ActivityStarted{
    ID:   nom.NewActivityID("compile"),
    Name: nom.NewActivityName("Compile"),
})
// ... do work ...
sub.OnEvent(ctx, nom.ActivityCompleted{
    ID:       nom.NewActivityID("compile"),
    Name:     nom.NewActivityName("Compile"),
    Duration: 5 * time.Second,
})

Features

• Dependency trees — Hierarchical parent/child relationships with UTF-8 box-drawing
• O(1) activity counts — Summary bar updates in constant time, even with 10,000+ activities
• Timing cache — Persists duration history for ETA estimates
• Progress sub-steps — ActivityProgress events render a dim sub-line beneath each activity
• Retry visibility — ActivityRetrying events render retry indicators
• Estimated remaining time — Powers a ~Xm left summary segment
• Snapshot-based rendering — Race-free: immutable value copies
• CI-safe degradation — Auto-detects CI; appends frames line-by-line instead of ANSI cursor codes
• Height-pressure collapse — Completed children collapse when the tree exceeds maxHeight

Events

Events are typed structs — the Event interface is sealed:

Event	Purpose
WorkflowStarted	Begin a workflow
WorkflowCompleted	End a workflow successfully
WorkflowFailed	End a workflow with failure
ActivityRegistered	Register an activity without starting it
ActivityStarted	Begin an activity (with optional deps)
ActivityCompleted	Mark an activity as completed
ActivityFailed	Mark an activity as failed
ActivityProgress	Set a live sub-step message
ActivityRetrying	Transition failed activity back to running

Themes

Five built-in theme presets: ThemeDefault, ThemeDracula, ThemeNord, ThemeMonochrome, ThemeHighContrast.

sub := nom.NewNOMSubscriber(nom.WithTheme(nom.ThemeDracula))

Interactive TUI

For a full-screen interactive experience, use the Bubble Tea TUI:

import "github.com/larsartmann/go-output/tui"

reporter := tui.NewBubbleTeaProgressReporter()
reporter.SetDisplayMode(tui.DisplayModeNOM)
reporter.Start()
defer reporter.Stop()

See Quick Start for more on the TUI and display modes.