CatchLaw

An offline catch-legality reference for artisanal and recreational fishers.

You have just landed a fish. In under five seconds — with no signal, no account and wet hands — CatchLaw states whether it meets the rules where you are standing, and if not, which rule it fails: below the minimum size, inside a closed season, protected, or past your bag limit. It shows how that species is legally measured, because "length" means five different things depending on what you are holding. And it cites the actual ministerial decision or regional order the number came from, with the date that text was last checked.

It runs 100% offline. No server, no account, no sync, no network code path at all.

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Why this exists

At 05:40 off Ras Al Khaimah, a fish is alive in the bin and looks marginal. There is no signal. Hands are wet and covered in slime. There are perhaps ten seconds before returning it stops being worthwhile. Getting it wrong costs AED 3,000 and a six-month licence suspension.

Today the answer is a guess, a laminated card two seasons out of date, or a screenshot of a government web page taken while still in port.

The strongest single piece of evidence behind this project is that the Ras Al Khaimah Fishermen's Association built and distributed its own app (Emarat Al Youm, 2019-07-08) — giving as its stated reason that the previous one required internet and most fishermen at sea could not use it. That is demand demonstrated by expenditure, not by complaint.

Status

Specification and design complete. No application code yet.

This repository currently holds the research, the specification, three design directions, and the engineering guidance needed to build it.

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Repository map

Path	What it is
SPEC.md	The complete, build-ready specification. Persona, feature list, screen inventory, SQL schema, bundled data and licences, localisation plan, tech stack, platform specifics, data portability, build order, riskiest assumptions, offline verification checklist.
IDEAS.md	The 24-candidate longlist the winner came from, with evidence strength and sources per candidate.
SHORTLIST.md	Five candidates deep-dived and scored against a weighted rubric, with competitor analysis and verified licensing.
REVIEW-CHANGES.md	What a three-reviewer adversarial pass found — 5 blockers, 20 major, 5 minor — and what changed. Includes the errors it caught in the first draft.
FLUTTER_GUIDE.md	How to write the code: architecture, project structure, naming, lints, state management, testing, Dart 3, performance, l10n/RTL. Researched from primary sources against Flutter 3.44.6 / Dart 3.12.2.
design/	Three complete HTML design directions, 20 screens each. Lonja is the chosen direction.
.claude/skills/	16 Claude Code Agent Skills — nine for the Lonja design system, seven for the CatchLaw domain.
research/	Phase-1 discovery: 14 parallel search lanes, raw findings with URLs and dates.
research-flutter/	Flutter best-practice research, 10 lanes, ~15,500 lines, primary sources only.
research-skills/	How Claude Code Agent Skills actually work — the verified spec, authoring craft, and house style.

The design: Lonja

Three directions were built and compared screen-for-screen. Lonja was chosen: the app as an authoritative printed document — the regulations booklet and the 19th-century ichthyological plate, carried in an oilskin pocket. Its authority comes from looking like the law and the field guide it actually quotes.

Token	Value	Role
paper	#E6E4DC	surface — cool bone with a green-grey bias, not warm cream
ink	#16201C	primary text — green-black, never pure black
harbour	#1B4D5E	accent — the blue of Galician fish crates and hull paint
verdant	#2E5E3A	semantic: meets the rule
oxblood	#7A2320	semantic: fails the rule
ochre	#8A6A16	semantic: rule data is stale

Serif for legal text (it is a legal document), monospace with tabular figures for every measurement, code and citation. No shadows, no gradients, no elevation — paper does not float.

Three themes, not two: paper, night, and sunlight — a genuine third palette where every grey is deleted and one colour survives. Plus glove mode, an orthogonal density switch raising every primary target to 56 dp.

The rules that are not style preferences

Four constraints in this app are legal or safety boundaries, and the skills enforce them mechanically:

1. The result is a statement of fact, never an instruction. "Below the minimum — 38 cm, minimum 45 cm (total length)". Never "Keep", never "Return". check_verdict_contract.sh fails the build on an imperative in any .dart or .arb file.
2. Every result carries its citation — instrument, article, publication date, last-checked date.
3. The app refuses to resolve genuine legal ambiguity. Where two equally specific rules apply it shows both and picks neither.
4. An expired ruleset is still evaluated and shown behind a non-blocking amber bar. A stale rule beats no rule at sea — and filtering expired rules out would turn a defensible frozen snapshot into a live-data product.

Offline is proved, not asserted

Four layers, strongest first:

1. The dependency is not declared — importing a networking package is a compile error.
2. android.permission.INTERNET is absent from the release manifest — the OS refuses every socket. This is the only layer a third party can verify without reading source.
3. iOS has no equivalent opt-out. Stated plainly rather than papered over; iOS rests on layers 1 and 4.
4. A guard test bans the networking half of dart:io, which cannot be banned wholesale because File, Directory and Platform are needed for the databases and PDF export.

Verification is a real packet capture, not an HTTP proxy — Dart's HttpClient ignores the system proxy unless findProxy is set.

Claude Code skills

.claude/skills/ holds 16 skills, each with references/, examples/ and a runnable scripts/*.sh gate.

Lonja design system (9) — lonja-design-tokens · lonja-typography · lonja-buttons · lonja-navigation-chrome · lonja-forms-and-controls · lonja-lists-and-tables · lonja-dialogs-and-surfaces · lonja-icons-and-plates · lonja-verdict-and-status

CatchLaw domain (7) — catchlaw-conventions-index · catchlaw-offline-guarantee · catchlaw-reference-database · catchlaw-content-pipeline · catchlaw-rule-engine · catchlaw-verdict-contract · catchlaw-measurement-ruler

These deliberately carry only token values and app-domain rules. General Flutter practice — architecture, naming, testing, clean code, performance — lives in the separate Flutter-Skills plugin and is cross-referenced, never restated.

Start with catchlaw-conventions-index; it routes any task to the skill that owns it.

Licence

Not yet chosen. The bundled content has its own licensing story — legal texts are outside copyright by statute in Spain (Art. 13 LPI), Brazil (Lei 9.610/1998 art. 8 IV) and the UAE (Federal Decree-Law 38/2021 Art. 3), but species artwork must be originated or cleared per image by the illustrator's death year, not by publication date. See SPEC.md §8.

A note on the evidence

Every demand claim in this repository carries a URL and a date. Where a source could not be verified it is marked unverified rather than dressed up, and REVIEW-CHANGES.md records the claims that did not survive checking — including one that the cited source did not actually support, and four competitors the first pass missed.

Reddit is unreachable from the environment this research ran in. No Reddit citation appears anywhere; equivalent primary sources were substituted and the limitation is disclosed in research/raw-findings.md.