[ TRACE ] · [ STEP ] · [ EMIT ] · [ SYNC ] · [ FORK ] · [ AWAIT ] · [ PIPE ] · [ CALL ] · [ READ ] · [ WRITE ] · [ MONITOR ] · [ OBSERVE ] · [ NODE ] · [ RUN ] · [ FAULT ] · [ RESOLVE ] · [ DISPATCH ] · [ CAPTURE ] [ TRACE ] · [ STEP ] · [ EMIT ] · [ SYNC ] · [ FORK ] · [ AWAIT ] · [ PIPE ] · [ CALL ] · [ READ ] · [ WRITE ] · [ MONITOR ] · [ OBSERVE ] · [ NODE ] · [ RUN ] · [ FAULT ] · [ RESOLVE ] · [ DISPATCH ] · [ CAPTURE ]

// Instrumentation Layer · v0.1.0-alpha

M.O.L.A.

Monitor & Observe Live Application Traces

A real-time debugger that lives inside your codebase.
Instrument async functions with two markers. Watch every node, every step, and every failure as it happens.

See how it works

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// ── what is mola ─────────────────────────────────────────────────

01 ──

Instrument in minutes

Add two comment markers and two wrapper calls to any async function. The AST parser extracts your step structure automatically — no config files, no schemas.

02 ──

See every execution

A local dev server buffers 500 events per node. Every run, step outcome, duration, and thrown error is visible in the UI — even if the tab wasn't open.

03 ──

Debug without guessing

Select any node or step and see its source context, last return value, and fault paths. Time-travel to any past run and compare states.

// ── features ──────────────────────────────────────────────────────

Built for the
way you actually debug

Every detail of Mola is designed around how async code fails in production — not how it looks on a diagram.

UI ●

Live Node Graph

Pan and zoom a real-time graph of all instrumented nodes. Edges are inferred automatically from async call chains via AsyncLocalStorage context. Animated packets travel active edges.

UI ◌

Step Pipeline

Expand any node to see its full step execution timeline — each step labeled, timed, and color-coded. Fault paths render below failing steps with exact error messages.

UI ●

Inspector Panel

Click any node or step to see source location, description, last return value, ASCII progress bar, and complete fault path list in a clean sidebar.

Runtime ○

Time-Travel Snapshots

Click any past run in the diagnostic console to replay system state at that exact moment. Step through executions, compare runs, return to live with one click.

Runtime ●

Edge Inference

No manual graph wiring. Parent node context propagates automatically through AsyncLocalStorage — call a traced function from inside another traced function and the edge appears.

UI ✕

Deep Dive Terminal

Launch a full xterm.js terminal session from any node or step in one click. Saved sessions persist as Markdown. Debug in context without switching windows.

// ── how it works ───────────────────────────────────────────────────

Instrument

Add @mola-node and @mola-step markers to any async function alongside matching traceNode() and traceStep() wrappers. One import, two patterns.

npm install @mola5/tracer

Start the server

Run npx mola start alongside your application. The dev server parses your source files, registers node manifests, and opens a WebSocket for live events.

npx mola start → localhost:4242

Observe

Open the Mola UI. Every function invocation streams in live — nodes light up, steps progress, errors surface with full context. Click anything to inspect it.

localhost:5173 → live dashboard

// ── instrumentation ────────────────────────────────────────────────

      src/orders/processor.ts
      TypeScript
    
1import { traceNode, traceStep } from '@mola5/tracer';
2
3// @mola-node: order-processor
4export const processOrder = traceNode('order-processor', async (orderId: string) => {
5  let cart, payment;
6
7  // @mola-step: 1_validate_cart
8  cart = await traceStep('1_validate_cart', async () => {
9    const c = await db.getCart(orderId);
10    if (!c.isValid) {
11      // @mola-error: cart_expired
12      throw new Error('Cart contains expired items');
13    }
14    return c;
15  });
16
17  // @mola-step: 2_charge_payment
18  payment = await traceStep('2_charge_payment', async () => {
19    return await stripe.charge(cart.total, cart.paymentMethod);
20  });
21
22  // @mola-step: 3_fulfill_order
23  await traceStep('3_fulfill_order', async () => {
24    await fulfillment.ship({ orderId, payment });
25  });
26
27});

M.O.L.A.

Built for theway you actually debug

Be first in.

Built for the
way you actually debug