feat: repeater CSV ingest, load, and rank-ordered search

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

repeaters.py

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+"""
+Repeater directory: ingest a RepeaterBook CSV export into a normalized
+repeaters.json, then load / text-search / rank it. Pure logic + small file I/O;
+no radio, no network.
+
+CSV is RepeaterBook's proximity export (nearest-first), so file order IS the
+distance ranking -> each record carries an integer `rank`.
+
+Normalized record schema:
+  callsign, location, output_mhz, offset_mhz, duplex ("+"/"-"/"simplex"),
+  tone_hz (or None), tone_mode ("ctcss"/"none"), mode ("FM"/"DV"),
+  rank (int), notes
+
+Usage:
+  python3 repeaters.py ingest repeaterbook/RB_xxxx.csv [repeaters.json]
+"""
+import csv
+import json
+import sys
+
+# US state -> USPS abbreviation (only the ones this export touches; extend freely)
+_STATE_ABBR = {
+    "Virginia": "VA", "Maryland": "MD", "District of Columbia": "DC",
+    "Pennsylvania": "PA", "West Virginia": "WV", "Delaware": "DE",
+    "New Jersey": "NJ", "North Carolina": "NC",
+}
+
+
+def _f(val):
+    """Parse a possibly-empty numeric string to float, else None."""
+    try:
+        return float(val)
+    except (TypeError, ValueError):
+        return None
+
+
+def normalize_csv(row, rank):
+    """Map a RepeaterBook CSV row (dict) + its file rank to the internal schema."""
+    out = _f(row.get("Output Freq"))
+    inp = _f(row.get("Input Freq"))
+    sign = (row.get("Offset") or "").strip()
+    if out is not None and inp is not None and sign in ("+", "-"):
+        duplex = sign
+        offset = round(abs(inp - out), 5)
+    else:
+        duplex, offset = "simplex", 0.0
+
+    tone = _f(row.get("Uplink Tone"))
+    city = (row.get("Location") or "").strip()
+    state = (row.get("State") or "").strip()
+    location = ", ".join(p for p in (city, _STATE_ABBR.get(state, state)) if p)
+
+    modes = (row.get("Modes") or "").upper()
+    mode = "FM" if "FM" in modes else ("DV" if "DSTAR" in modes else "FM")
+
+    return {
+        "callsign": (row.get("Call") or "").strip(),
+        "location": location,
+        "output_mhz": out,
+        "offset_mhz": offset,
+        "duplex": duplex,
+        "tone_hz": tone,
+        "tone_mode": "ctcss" if tone else "none",
+        "mode": mode,
+        "rank": rank,
+        "notes": "",
+    }
+
+
+def load(path):
+    """Read a normalized repeaters.json (list of records). Missing file -> []."""
+    try:
+        with open(path) as f:
+            data = json.load(f)
+    except FileNotFoundError:
+        return []
+    return data if isinstance(data, list) else data.get("repeaters", [])
+
+
+def search(records, q, limit=25):
+    """Filter by case-insensitive substring (callsign/location), keep rank order."""
+    q = (q or "").strip().lower()
+    out = [r for r in records
+           if not q or q in f"{r.get('callsign','')} {r.get('location','')}".lower()]
+    out.sort(key=lambda r: r.get("rank", 1_000_000))
+    return out[:limit]
+
+
+def ingest_csv(csv_path, out_path):
+    """Read a RepeaterBook CSV, filter to FM/DSTAR on 2m/70cm, write repeaters.json.
+    Returns the number of records written. File order is preserved as `rank`."""
+    recs = []
+    with open(csv_path, newline="") as f:
+        for i, row in enumerate(csv.DictReader(f)):
+            rec = normalize_csv(row, i)
+            f_mhz = rec["output_mhz"]
+            if f_mhz is None:
+                continue
+            modes = (row.get("Modes") or "").upper()
+            if "FM" not in modes and "DSTAR" not in modes:
+                continue
+            if not (144 <= f_mhz < 148 or 420 <= f_mhz < 450):
+                continue
+            recs.append(rec)
+    with open(out_path, "w") as f:
+        json.dump(recs, f, indent=1)
+    return len(recs)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) >= 3 and sys.argv[1] == "ingest":
+        out = sys.argv[3] if len(sys.argv) > 3 else "repeaters.json"
+        n = ingest_csv(sys.argv[2], out)
+        print(f"wrote {n} repeaters -> {out}")
+    else:
+        print("usage: python3 repeaters.py ingest <csv> [out.json]", file=sys.stderr)
+        sys.exit(2)