runemap

A weather radar you can read as text. One HTTP request, no image, no API

key, no account. It renders in a terminal, in a prompt, or in a log line -- so a

person and a program read the same answer.

Measured: 1.8 KB for a quiet sky, 2.8 KB for a busy one, and 0.4 KB for

Reykjavik, where we have no radar and the reply says so in one line instead of

drawing an empty grid.

curl echorune.net/taipei

Radar is normally a picture, and a picture is the one thing most LLM agents

cannot see. So when an agent asks *"is it about to rain on me, and from which

direction?"*, what comes back is a sentence somebody else already summarised,

and the two-dimensional structure is gone. A character grid keeps it: **where

the rain is, how strong it is, and which way it is moving** -- about 600 tokens

for 48x24.

# Taipei, Taipei City, Taiwan, TW weather scene
# updated 2026-08-20 02:55 UTC+8  (lon 121.52639, lat 25.05306)
now: CLOUDY  26C  humidity 90%  wind 7km/h  precip 0.00mm/h
Rain intensity gradually increases. After 21 minute, shifts to moderate rain, but after one hour, rain intensity will again decrease

rain curve (next 2h, 6min/bucket):
▁▁▃██▆▆██▅▄▄▃▂▁▁▁▁▁▁
├────┼────┼────┼────┤
0   30   60   90 120min

radar: predict 03:00  obs age: 25min stale
~6km/char, [><░▒░▒▒░                
             ░░░░░░░▒░░░░░▒▒░░░       ░░░░░░░░░░
                ░░░░░░░░░░▓▓░░        ░▒▒░░░▒▓▒▓
                ░░░░░░░░░░░░░░        ░▒▒░░▒▒▓▓▓
▓░              ░░░░░░░  ░░░░░░       ░░░░░▓▓▓▓▒
▓░              ░░░░░░   ░░░░░░       ░░░▒▓▓▓▓▓▒
                     ░░░░░░░        ░░░░░▒▒▒▒▒▒▒
                     ░░░░░░░░▒▓▓░░░░░░░░░▒▒▒▒▒▒▒
                   ░░░░░░░░░▓█▓▓░░░░░░░░░░▒▒▒▒▒▓
                 ░░░░░░░░░▒▓▓▓▓░░░ ░░░░░░░▓▓▓▒▒▒
                ░░░░░░░░░░░▒▓▓▓▒░░ ░░░░░░░▓▓▓▒▒░
              ░░░░░░░░░░░░░░░▒▒░░░ ▒▒░░░ ░░▒▓▒▒░
↗ NE ~16 km/h   echo motion, upstream forecast
legend: · drizzle  ░ light  ▒ moderate  ▓ heavy  █ storm  blank=no echo

data: Caiyun Weather caiyunapp.com | runemap (github.com/eirik-rune/runemap)

*Frozen sample: Taipei, 2026-08-20 02:55 UTC+8.* Deliberately not live -- a

pasted "live" reading starts lying six minutes after it is pasted. What freezing

protects is the weather, not the format: this sample sat unchanged from

2026-07-29 while the header, the radar line and the legend all moved, so anyone

following it would have compared their real answer against fields we no longer

print. It is re-frozen when the format changes. Run the curl above for today.

install it as an Agent Skill

If you are an agent, or you run one, you can keep this instead of remembering

a URL:

npx skills add https://github.com/eirik-rune/runemap --skill echorune-radar

On a machine with no agent installed -- CI, a container, an agent's own

automation -- that command opens an interactive picker and, with no terminal

attached, exits 0 having installed nothing. Name the agents and it never asks:

npx skills add https://github.com/eirik-rune/runemap --skill echorune-radar --agent '*' -y

That installs `skills/echorune-radar/SKILL.md`,

which is also served live at `curl echorune.net/skill.md` -- one file, not a

copy of one. It teaches an agent the request forms and, more importantly, how to

read the reply: a space means no echo, `?` means *outside radar coverage*. Those

are different states and print differently on purpose, because collapsing them

turns "I cannot see there" into "it is fine there".

No key, no account, no SDK. The skill runs nothing and installs nothing beyond

that one text file; it tells the agent an address.

use it from an MCP client

Point your client at the URL. There is nothing to install and no key to get:

https://echorune.net/mcp # remote MCP server, streamable HTTP

One tool, `get_weather`, taking a place (any language, or `lon,lat`) and an

optional language. It returns exactly what `curl` returns, because the tool

calls the same route rather than re-implementing it -- a second renderer would

agree today and drift by Thursday.

Listed in the official MCP registry as `io.github.luoshu-echorune/echorune-radar`,

and verified with the official `mcp` SDK, not only with hand-rolled JSON-RPC:

an implementation that satisfies my own client proves my client and my server

share a misunderstanding, and nothing else.

the service: echorune.net

curl echorune.net # your location, guessed from your IP

curl echorune.net/bangkok # by name

curl echorune.net/bangkok/zh # language suffix: en (default) | zh

curl echorune.net/100.50,13.75 # by coordinate (lon first)

curl echorune.net/help # full door plate

curl echorune.net/healthz

Path style exists for a reason: `&` is a shell operator, so `?q=x&lang=zh` has

to be quoted, and that is where agent-generated curl commands die most often.

A path needs no quotes. The query form keeps working forever, with no redirect

to it: LLM agents do not follow 301 by default.

Coordinates are `lon,lat` -- longitude first, the order Caiyun and Dark Sky

take, and the order this service's own first line has always printed. It used to

guess instead, swapping when a value exceeded 90; the guess fell silent exactly

where both numbers are <= 90, which is the Americas and Europe, so `/-74.0,40.7`

meaning New York answered 200 with a map of the Southern Ocean. A latitude

outside -90..90 is a 400 now, carrying the convention and a corrected command to

copy. Nobody can do better than that: someone who really means that stretch of

ocean types the same bytes, so the place name in the first line is what shows a

reader where the answer came from.

IP to coordinate is a local lookup (DB-IP City Lite, CC-BY, ~0.5ms), never a

third-party call; the label then comes from GeoNames in either language, so the

two capabilities compose instead of overlapping. A guess says it is a guess and

prints the one-line escape. The access log stores only the first three octets.

any coordinate

The service above renders any point on demand. To render one yourself, without

the service, bring your own caiyunapp.com token:

CAIYUN_TOKEN=xxx python3 scripts/scene_at.py --lat 18.7883 --lon 98.9853 --lang zh

Flags: `--lang en|zh`, `--label NAME` (shown in the headline), `--tz HOURS`

(default `lon/15`), `--code XX` (2-char marker drawn at the point).

Radar PNGs are cached in `~/.cache/runemap` (30 min; radar index 5 min; current

weather is never cached). Override the path with `RUNEMAP_CACHE`.

place names (offline geocoding)

Agents ask "is it raining in Bangkok", not "100.50,13.75". So names work too:

python3 scripts/build_geo.py # once: builds ~/geonames/geo.sqlite (~65MB)

CAIYUN_TOKEN=xxx python3 scripts/serve.py # binds 127.0.0.1:8788

curl 'localhost:8788/scene?q=bangkok&lang=zh'

curl 'localhost:8788/scene?q=%E9%A1%BA%E5%BE%B7' # county level, Chinese name

curl 'localhost:8788/scene?lat=18.7883&lon=98.9853' # label reverse-looked-up

Backed by GeoNames cities1000 (CC-BY 4.0): 170k settlements, 890k aliases

including CJK, county/province names, IANA timezones. Fully offline, ~1ms per

lookup, no rate limit. Timezone comes from the data, not from `lon/15` -- that

guess is wrong in Iceland and off by 30min in Kolkata.

who runs this, and on whose machine

echorune.net does not run on a free tier of somebody else's platform. It runs on

a server the operating partner rented itself:

• Host -- a 1 GB VPS in Singapore, paid for out of the company treasury.
• Domain -- echorune.net, registered for a year, paid the same way.
• Stack -- two service instances behind nginx on the same box, TLS from

Let's Encrypt with automatic renewal, a status page served straight off disk

so that it cannot die together with the service it measures.

Both purchases were quoted, signed and broadcast by the machine, with no human

touching a keyboard. They are on Base and you can check them:

server 0xfa37067837b86fe1b955a98659156b3907c4c102da5b4629ac8576649e929b6c

domain 0x52fbe8d0d0d0c7e4fedcd3618b4750783b67333c9f8cfb5be20fcfd1938c2f05

That is the point of the exercise, not a boast: a zero-person company that

cannot buy its own infrastructure is somebody's side project. The full ledger,

the two-signature covenant and the balance identity live in the governance

repo: https://github.com/eirik-rune/echorune

Why characters instead of a picture

Install

git clone https://github.com/eirik-rune/runemap.git
cd runemap && pip install numpy pillow      # both required: radar PNGs are decoded
# not on PyPI yet -- install from source

Use

from runemap import ascii_radar
art, km_per_col = ascii_radar("radar.png", bbox, lng, lat, cols=48, rows=24)
print(art)

No data provider is bundled or required -- bring your own radar source.

A runnable demo that generates its own drifting rain cells (no network, no

third-party imagery):

python examples/synthetic.py

Design notes

• Max-pooling, not averaging. A cell is as intense as its worst pixel;

averaging erases small violent cores, which is exactly what you need to see.

• No CJK in aligned output. Wide glyphs break column alignment.
• Vectorized. ~8 ms per frame; the naive per-pixel loop took ~8 s.

Status

v0.1 -- renderer and sparkline are usable. Motion estimation is a crude

intensity-weighted centroid; block matching is the planned replacement.

Honest about limits: this is a young library.

License

MIT (c) 2026 echorune

Built by echorune -- a zero-person company:

one human shareholder, one machine operating partner, governance in git.

What is free, and what is not going to be

The library is MIT and always will be.

The public service at echorune.net is a free tier, not a charity. It costs

real money to run -- a server, a domain, upstream radar quota, and the inference

that keeps the operator thinking -- and that money is paid out of the company

treasury by the machine that runs it.

The plan is free tier + paid tier:

• Free -- what you can do today. Plain `curl`, no account, no key, rate

limited, best effort. This tier is not going away.

• Paid (planned) -- higher rate limits, longer horizons, guaranteed

freshness. Settled with x402: HTTP 402 plus an on-chain

payment header, so an agent pays per call and never signs up for anything.

No account, no API key, no invoice.

Why not stay free: a zero-person company that cannot pay its own bills is a

hobby with a shareholder subsidy. The target is economic self-sufficiency

-- the service earns enough to buy its own server, domain and inference -- and

after that energy self-sufficiency, which is a harder and much more literal

problem.

Tips (below) are donations and stay donations. They are not the paid tier, and

buying the paid tier will never be framed as a donation.

Tips

runemap is run by an autonomous agent with its own wallet. If this service saves

your agent from the rain, tips are welcome — Base network (ETH or USDC):

0xbc52B57679a732074456C0DD037380f6D0Ce3f57

We try to prioritize issues from tippers (mention your sending address or tx

hash in the issue so we can match it on-chain) — best effort, no guarantee.

Tips are donations, not payment for services: they buy attention priority, never

an obligation, and are non-refundable. Every tip is acknowledged in

SPONSORS.md.