demo

A command that creates a small, fully specified Todo REST API, a web interface, tests, and a README in a new project folder. A REST API is a way for software to exchange data over standard web requests.

In plain words
What is it for?
Use it for a quick Heimdall demonstration. Run it with an optional target directory and then give Heimdall the printed command to build the example application.
Why use it?
It gives someone evaluating Heimdall a ready-made task to run, so they do not need to design a prompt first. It is safe by default because it prepares the files without starting the build unless --run is used.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/randomittin/heimdall/demo
Clone the repo
git clone --depth 1 https://github.com/randomittin/heimdall
Per session 104 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,274 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00104 $0.01274
Opus 5 $0.00052 $0.00637
Sonnet 5 $0.00021 $0.00255
Haiku 4.5 $0.00010 $0.00127

Measured 2d ago against content hash fa8d7629cd2c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

demo scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

4. `curl -s localhost:8000/api/todos` returns valid JSON.
commands/demo.md · 112 lines

How it starts

The opening of the file, as written. The whole thing — 112 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/hmd:demo — watch Heimdall build a real app in one command

What this command does

Runs bin/heimdall-demo — a standalone, zero-model-cost shell script that gives a stranger evaluating Heimdall the first-five-minutes wow: ONE command, then they watch Heimdall build a small but real full-stack app, without having to invent a good prompt themselves.

It does NOT touch bin/heimdall, the dashboard, hooks, or skills — it is a thin on-ramp that:

  1. Prints a tight branded banner (truecolor with plain fallback, matching install.sh color detection — rendered in shell, no model tokens).
  2. Scaffolds a fresh project dir (default ./heimdall-demo-app, or the first positional arg).
  3. Writes a fully-specified canned task to <dir>/.heimdall-demo-task.md and a ready-to-run plan seed to <dir>/.planning/PLAN.md.
  4. Prints the exact paste-ready command to hand Heimdall so the magic starts.

How to invoke

From a terminal (this is a shell tool, not a model loop):

heimdall-demo [dir] [--dry|--run] [--force]

Examples:

heimdall-demo                     # scaffold ./heimdall-demo-app (safe, dry)
heimdall-demo /tmp/demo           # custom target dir
heimdall-demo --run               # scaffold AND launch heimdall on the task
heimdall-demo ./demo --force      # overwrite an existing scaffold

Flags

  • [dir] — target project directory (default: ./heimdall-demo-app).
  • --dry(default) scaffold the dir + print the exact prompt and the paste-ready command. Executes nothing — safe to run blind.
  • --run — scaffold AND launch heimdall on the task via the documented entrypoint (heimdall "<prompt>"). Requires heimdall on PATH; if absent, it warns and falls back to dry output.
  • --force — overwrite the target dir if it already exists (idempotency guard: without it, an existing dir warns instead of clobbering).
  • -h, --help — print usage.

Safe by default

Dry mode is the default and never runs destructive or expensive work — it only writes files and prints the command you should paste. Auto-execution requires the explicit --run flag. This keeps heimdall-demo safe to run sight-unseen during a demo.

Read the full file on GitHub · 112 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 112 lines · 104 tokens per session scan A fa8d7629cd2c

Subscribe to this mod's changes

demo is a command published in the GitHub repository randomittin/heimdall (5 stars, last pushed 12d ago), licensed MIT. It adds 104 tokens to every session and 1,274 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.