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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## What this is
+
+A CLI that looks up Swedish phone numbers ("who is calling me?") by scraping
+reverse-lookup sites. Old codebase: Rust edition 2018, reqwest 0.9 (synchronous
+API), insta 0.11.
+
+## Commands
+
+```bash
+cargo build
+cargo run -- 0700000000                          # query a number (hitta.se built in)
+cargo run -- -d definitions/vem_ringde.toml 0700000000   # add TOML-defined probes
+cargo run -- -o 0700000000                       # open probe URLs in browser (macOS `open`)
+
+cargo test                                       # all tests (insta snapshot tests)
+cargo test probe::hitta                          # one module
+cargo test test_0104754350                       # one test
+
+cargo +nightly fmt                               # always nightly, not stable
+cargo clippy
+```
+
+Tests are inline-snapshot tests (`assert_yaml_snapshot!(..., @r###"..."###)`)
+against checked-in HTML fixtures in `fixtures/<provider>/<number>.html` — no
+network needed. Refresh/add fixtures with `./fetch-fixture <number>` (requires
+`http`/httpie); it fetches the number from all five sites into `fixtures/`.
+
+## Architecture
+
+Everything revolves around the `Probe` trait (`src/probe.rs`): `provider()`,
+`uri(number)`, `fetch(number)`, `parse(html) -> Result<Entry, ()>`.
+
+Two kinds of probes:
+
+1. **Hard-coded**: `Hitta` (`src/probe/hitta.rs`) — extracts the
+   `__NEXT_DATA__` JSON blob via regex and deserializes it with serde. Always
+   registered in `main.rs`.
+2. **Declarative**: `Definition` (`src/definition.rs`) — generic scraper
+   configured by a TOML file (`definitions/*.toml`) with CSS selectors for
+   `messages`, `history`, and `comments` (each comment has optional
+   `date_time`/`title`/`message` sub-selectors). The URL `path` is a
+   tinytemplate string with `{ number }`. Loaded at runtime via `-d`.
+
+Flow in `main.rs`: build probe list → for each probe, check the cache
+(`Context` in `src/context.rs`, bincode files under the platform cache dir
+with a 1-day TTL) → otherwise `fetch()` and cache → `parse()` into an `Entry`
+(`src/entry.rs`) → `Display` it.
+
+## Gotchas
+
+- `src/probe/{eniro,konsument_info,telefonforsaljare,vem_ringde}.rs` are
+  **orphaned** — `probe.rs` only declares `mod hitta;`. Those providers were
+  superseded by the TOML definitions in `definitions/`. Don't "fix" them or
+  expect them to compile; they're kept as reference.
+- `_build.rs` is intentionally disabled (underscore prefix, not referenced in
+  Cargo.toml) — an abandoned attempt at generating fixture tests.
+- `definitions/vem_ringde.yml` is an experimental YAML variant of the TOML
+  definition, but `main.rs` only parses TOML (`toml::from_slice`).
+- The `Filter` enum in `src/definition.rs` has no variants yet — `filters` is
+  parsed from definitions but unimplemented (commented-out loops in `parse`).
+- insta 0.11 is old: the macro is `assert_yaml_snapshot!` and inline-snapshot
+  updates need a matching old `cargo-insta`; it's usually easier to update the
+  inline `@r###"..."###` literals by hand.