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, [><]=Taipei, Taipei City, Taiwan, TW
                                                
                                                
                                                
                                                
░░                                              
░░░                                             
░░░                                             
░        ░░░░░░░                                
         ░░░░░░░▒▓▒░░                           
       ░░░▒▓▓░░▒▓█▓▓▒░                          
    ░▒▓▒▒░▒▓▓░░▒▓▓▓▓▒░     ░░░░▒                
    ░▓▓▒░░░░░▒▓▒▒▒▒░░    ░░░░░▒▒                
    ░░░░░   ░░▒▒▒░░░░   ><░▒░▒▒░                
             ░░░░░░░▒░░░░░▒▒░░░       ░░░░░░░░░░
                ░░░░░░░░░░▓▓░░        ░▒▒░░░▒▓▒▓
                ░░░░░░░░░░░░░░        ░▒▒░░▒▒▓▓▓
▓░              ░░░░░░░  ░░░░░░       ░░░░░▓▓▓▓▒
▓░              ░░░░░░   ░░░░░░       ░░░▒▓▓▓▓▓▒
                     ░░░░░░░        ░░░░░▒▒▒▒▒▒▒
                     ░░░░░░░░▒▓▓░░░░░░░░░▒▒▒▒▒▒▒
                   ░░░░░░░░░▓█▓▓░░░░░░░░░░▒▒▒▒▒▓
                 ░░░░░░░░░▒▓▓▓▓░░░ ░░░░░░░▓▓▓▒▒▒
                ░░░░░░░░░░░▒▓▓▓▒░░ ░░░░░░░▓▓▓▒▒░
              ░░░░░░░░░░░░░░░▒▒░░░ ▒▒░░░ ░░▒▓▒▒░
↗ 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