danish-building-years: Skill for Claude Code

.agents/skills/add-building-year-city/SKILL.md

add-building-year-city is a skill for Claude Code, Codex from kasperjunge/danish-building-years. It costs 44 tokens per session (1,044 once invoked), scanned A, original, MIT.

A workflow for adding a Danish city or town to a map of building construction years. It updates the place data using national building records and map context, then checks the Svelte app.

In plain words
What is it for?
Useful for choosing a city identifier, extracting Danish BBR building data, adding OpenStreetMap context, updating places.json, and verifying the map.
Why use it?
It reduces the manual work and mistakes involved in finding the right addresses, geographic bounds, and source data for a new place.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is kasperjunge/danish-building-years's own configuration. It tells Claude Code and Codex how to work on danish-building-years itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything danish-building-years configures →

Reuse

Borrowing it

Nothing to install: this file belongs to kasperjunge/danish-building-years. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/kasperjunge/danish-building-years/main/.agents/skills/add-building-year-city/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/kasperjunge/danish-building-years

Made for: Claude Code, Codex.

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Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,044 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00044 $0.01044
Opus 5.5 $0.00018 $0.00418
Sonnet 5.5 $0.00009 $0.00209
Haiku 4.5 $0.00004 $0.00104

Measured 2mo ago against content hash fa37baf0291b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

add-building-year-city scanned grade A with 0 findings 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 2mo 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/add-building-year-city/SKILL.md · 134 lines

How it starts

The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Add a City to Danish Building Years

Use this skill from the repository root when the user asks to add another city/town to the building-year map.

Workflow

  1. Pick a city id, display name, postal string, and bbox.

    • id: lowercase ASCII slug, e.g. roskilde.
    • name: display name, e.g. Roskilde.
    • postal: BBR postal string, e.g. 4000 Roskilde.
    • bbox: south,west,north,east.
  2. Probe BBR address formatting before extraction.

sqlite3 data/downloads/DK_INSPIRE_BBR.gpkg <<'SQL'
.headers on
.mode tabs
select addressRepresentation
from building
where addressRepresentation like '%CITY_OR_POSTAL%'
limit 30;
SQL

Common patterns:

  • Small localities may be stored as Street, Locality, Postal City, so use BBR_LOCALITY and BBR_POSTAL.
  • Larger postal cities may be stored as Street, Postal City, so use BBR_ADDRESS_PATTERN='%, 4000 Roskilde'.
  • Danish letters are not always used in locality names; Årsdale is stored as Aarsdale.
  1. Make sure the national BBR GeoPackage exists.
uv --project api run building-years download-bbr
  1. Generate the city with the root command.

For postal-pattern cities:

uv --project api run building-years add-city \
  --id roskilde \
  --name "Roskilde" \
  --postal "4000 Roskilde" \
  --bbox "55.613,12.03,55.675,12.145"

For locality-based cities:

uv --project api run building-years add-city \
  --id svaneke \
  --name "Svaneke" \
  --locality "Svaneke" \
  --postal "3740 Svaneke" \
  --bbox "55.13,15.13,55.1455,15.1555"

For exact BBR address patterns:

uv --project api run building-years add-city \
  --id aarsdale \
  --name "Årsdale" \
  --postal "3740 Svaneke" \
  --address-pattern "%, Aarsdale, 3740 Svaneke" \
  --bbox "55.1005,15.134,55.1145,15.1585"

The command generates OSM buildings/context, extracts BBR points/records, and updates data/places.json.

  1. If manually editing data/places.json, use this shape:
{
  "id": "roskilde",
  "name": "Roskilde",
  "bbrLocality": "",
  "postal": "4000 Roskilde",
  "bbox": {
    "south": 55.613,
    "west": 12.03,
    "north": 55.675,
    "east": 12.145
  },
  "files": {
    "buildings": "roskilde-osm-buildings.geojson",
    "context": "roskilde-osm-context.geojson",
    "bbrPoints": "roskilde-bbr-inspire-points.geojson",
    "bbrRecords": "roskilde-bbr-inspire-records.json"
  }
}

Read the full file on GitHub · 134 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. 2mo ago First seen · 134 lines · 44 tokens per session scan A fa37baf0291b

Subscribe to this mod's changes

add-building-year-city is a skill published in the GitHub repository kasperjunge/danish-building-years (5 stars, last pushed 3mo ago), licensed MIT. It adds 44 tokens to every session and 1,044 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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