Trace

One incident. Every trace.

🏆 Winner — 1st Place, Agentic AI Track at JacHacks 2026

Trace keeps a disaster as one persistent graph of sources, claims, people and alerts, so a new report sits beside the old ones instead of overwriting them.

Maya's story, start to finish: reported missing, matched, reported safe, traced to its source.

After a flood, the police say Maya is missing. A day later a hospital says she is safe. Most tools would flip a status field and lose the first report. Trace keeps both, alerts the family member who subscribed to her, and can tell you where each report got its information.

It is one Jac app with five tabs: Map, People, Media, Sources and Graph. All people, organizations and reports are fictional.

How it works

Every screen reads the same graph. A source publishes a claim about a person; a walker follows the edges from that claim to the people subscribed to her and writes an alert.

1. Reports are kept, never replaced

The police MISSING report and the hospital FOUND_SAFE report both stay on Maya's timeline, each with who said it and when. The status shown is a cited summary of those reports.

2. A person decides whether two records are the same

"Maya Gurung" and "Maya G." might be one person. Trace lists the rule-based similarities, the differences and what is unknown, then waits for a reviewer. Both records stay separate either way.

3. The model labels, Jac decides

A volunteer post says "According to Nepal Police". NVIDIA Nemotron labels the attribution (direct, relay or unclear). Jac then chooses the next step: stop, retrieve the named source and compare, or hand it to a person. Labels come from the model; every action, traversal, timestamp and number comes from Jac.

4. The graph is the app

The Graph tab draws the stored nodes and typed edges behind every other tab, with live physics written in Jac and no graph library.

Switch to Jac's built-in viewer and the same tab shows every node on the server. With the exercise corpus loaded that is 7,094 nodes and 11,307 edges.

Run it

You need the Jac 0.34.1 native binary, the version this was tested with. Do not substitute another CLI version or the jaclang PyPI package. See the official installation guide.

jac --version
jac install
jac start --dev main.jac

Open the URL printed by the server and follow the story bar at the top: four steps, each with a button that runs the real action. Run only one server against this checkout's .jac/data/ graph store. The core story needs no model credentials.

Live model checks (optional)

Setting	Value
Model	nvidia_nim/nvidia/nemotron-3.5-lightning-30b-a3b (NVIDIA hosted API)
Client	Jac by llm() (byLLM) over litellm 1.102.1, typed enum outputs
Call settings	temperature 0, 96 output tokens, no retries, reasoning off, 45 s limit
Prompt version	report-lineage-v4
Calls per check	at most 2 (attribution, then one source comparison for a relay)

Environment variable	Purpose
NVIDIA_NIM_API_KEY	NVIDIA API key, server-side only.
TRACE_LIVE_PASSPHRASE	Required for live checks (typed into the People panel) and, when set, for publishing, PFIF import and media changes. Unset means live checks are off and nothing is locked.
TRACE_MODEL_REQUEST_CAP	Optional lifetime request cap for the server's ledger (default 200, 1-1000).
LITELLM_LOCAL_MODEL_COST_MAP=True	Stops litellm downloading its price list at startup.

Every request is written to .trace-local/model-usage.json before it is sent and is never refunded; Reset does not touch it. Details, statuses and the evaluated cases are in docs/INVESTIGATION.md.

What is real and what is not

Publishing, alerts, identity review, the timeline, SHA-256 copy matching of uploaded images and the graph all run on stored data. The seeded media checks (EXIF, C2PA, synthetic-media) are simulated and labeled as such in the UI. The two source checks shown on first load are real recorded Nemotron runs, labeled REPLAYED. There is no authentication, continuous monitoring or external alert delivery.

The full list is in docs/LIMITS.md.

Tests

jac test tests features/people/test_identity_review.jac features/graph/test_graph.jac features/media/test_media.jac features/media/test_media_integration.jac
jac build --check_only
jac build --client web

The investigation suite uses a mock model and a temporary ledger; it makes no network or paid model calls.

More documentation

Page	What it covers
docs/DEMO.md	The guided story step by step, the write lock, and what happens when live checks are unavailable
docs/LIMITS.md	Current behavior and limits of every tab
docs/MAP.md	Map data sources, pin rules and the browser checks
docs/INVESTIGATION.md	The Nemotron source check: setup, request cap, ledger, statuses and tests
docs/PUBLISHING.md	Report validation, provenance, alerts and reset
docs/TEAM.md	Ownership, tab interfaces and integration checks
AGENTS.md	Engineering and evidence rules

Code map

Path	Responsibility
main.jac	Endpoint registration, CSS entry, and route
components/TraceDashboard*, components/shared/	Shared shell and presentation
features/<tab>/	Tab UI, feature services, and focused tests
graph/nodes.jac, graph/edges.jac, graph/activity.jac	Persistent schema and activity helpers
walkers/	Ingestion, identity proposals/reviews, seeded and upload evidence, watching
services/trace.jac, services/geo.jac	Shared snapshot/actions and boundary data
services/investigation.jac, integrations/nemotron.jac	Report checks and the model boundary (typed labels, passphrase, ledger)
demo/seed.jac, demo/reset.jac, tests/	Executable fixtures, isolated reset, and tests
styles/trace-tokens.css	Trace theme tokens; imports generated global.css

.jac/ and dist/ are generated/ignored. .jac/data/ holds local graph data; .trace-local/ holds the persistent model request ledger. Neither is source code or a cleanup target. geometry.topo.json is required map data.

Dataset rules and their linked schemas describe a future corpus, not current fixtures or APIs.

Team

Built in one night at JacHacks 2026 by four undergraduates learning Jac as they went.

Person	Owned
Anshu Pathak	Sources and Map tabs, ingestion, shared integration
Miguel Orti Vila	Graph tab and the graph schema
Gabriel Salvatore	People tab and identity matching
Aidana Kuat Adilbekyzy	Media tab and evidence checks