diff --git a/src/holt59/aoc/2022/day15.py b/src/holt59/aoc/2022/day15.py
index ba537aa..fb13272 100644
--- a/src/holt59/aoc/2022/day15.py
+++ b/src/holt59/aoc/2022/day15.py
@@ -1,90 +1,96 @@
 import sys
-from typing import Any
+from typing import Any, Iterator
 
 import numpy as np
 import parse  # type: ignore
 from numpy.typing import NDArray
 
-
-def part1(sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], row: int) -> int:
-    no_beacons_row_l: list[NDArray[np.floating[Any]]] = []
-
-    for (sx, sy), (bx, by) in sensor_to_beacon.items():
-        d = abs(sx - bx) + abs(sy - by)  # closest
-
-        no_beacons_row_l.append(sx - np.arange(0, d - abs(sy - row) + 1))  # type: ignore
-        no_beacons_row_l.append(sx + np.arange(0, d - abs(sy - row) + 1))  # type: ignore
-
-    beacons_at_row = set(bx for (bx, by) in sensor_to_beacon.values() if by == row)
-    no_beacons_row = set(np.concatenate(no_beacons_row_l)).difference(beacons_at_row)  # type: ignore
-
-    return len(no_beacons_row)
+from ..base import BaseSolver
 
 
-def part2_intervals(
-    sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], xy_max: int
-) -> tuple[int, int, int]:
-    from tqdm import trange
+class Solver(BaseSolver):
+    def part1(
+        self, sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], row: int
+    ) -> int:
+        no_beacons_row_l: list[NDArray[np.floating[Any]]] = []
+
+        for (sx, sy), (bx, by) in sensor_to_beacon.items():
+            d = abs(sx - bx) + abs(sy - by)  # closest
+
+            no_beacons_row_l.append(sx - np.arange(0, d - abs(sy - row) + 1))  # type: ignore
+            no_beacons_row_l.append(sx + np.arange(0, d - abs(sy - row) + 1))  # type: ignore
+
+        beacons_at_row = set(bx for (bx, by) in sensor_to_beacon.values() if by == row)
+        no_beacons_row = set(np.concatenate(no_beacons_row_l)).difference(
+            beacons_at_row
+        )  # type: ignore
+
+        return len(no_beacons_row)
+
+    def part2_intervals(
+        self, sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], xy_max: int
+    ) -> tuple[int, int, int]:
+        for y in self.progress.wrap(range(xy_max + 1)):
+            its: list[tuple[int, int]] = []
+            for (sx, sy), (bx, by) in sensor_to_beacon.items():
+                d = abs(sx - bx) + abs(sy - by)
+                dx = d - abs(sy - y)
+
+                if dx >= 0:
+                    its.append((max(0, sx - dx), min(sx + dx, xy_max)))
+
+            its = sorted(its)
+            _, e = its[0]
+
+            for si, ei in its[1:]:
+                if si > e + 1:
+                    return si - 1, y, 4_000_000 * (si - 1) + y
+                if ei > e:
+                    e = ei
+
+        return (0, 0, 0)
+
+    def part2_cplex(
+        self, sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], xy_max: int
+    ) -> tuple[int, int, int]:
+        from docplex.mp.model import Model
+
+        m = Model()
+
+        x, y = m.continuous_var_list(2, ub=xy_max, name=["x", "y"])
 
-    for y in trange(xy_max + 1):
-        its: list[tuple[int, int]] = []
         for (sx, sy), (bx, by) in sensor_to_beacon.items():
             d = abs(sx - bx) + abs(sy - by)
-            dx = d - abs(sy - y)
+            m.add_constraint(
+                m.abs(x - sx) + m.abs(y - sy) >= d + 1, ctname=f"ct_{sx}_{sy}"
+            )  # type: ignore
 
-            if dx >= 0:
-                its.append((max(0, sx - dx), min(sx + dx, xy_max)))
+        m.set_objective("min", x + y)
 
-        its = sorted(its)
-        _, e = its[0]
+        s = m.solve()
+        assert s is not None
 
-        for si, ei in its[1:]:
-            if si > e + 1:
-                return si - 1, y, 4_000_000 * (si - 1) + y
-            if ei > e:
-                e = ei
+        vx = int(s.get_value(x))
+        vy = int(s.get_value(y))
+        return vx, vy, 4_000_000 * vx + vy
 
-    return (0, 0, 0)
+    def solve(self, input: str) -> Iterator[Any]:
+        lines = input.splitlines()
 
+        sensor_to_beacon: dict[tuple[int, int], tuple[int, int]] = {}
 
-def part2_cplex(
-    sensor_to_beacon: dict[tuple[int, int], tuple[int, int]], xy_max: int
-) -> tuple[int, int, int]:
-    from docplex.mp.model import Model
+        for line in lines:
+            r: dict[str, str] = parse.parse(  # type: ignore
+                "Sensor at x={sx}, y={sy}: closest beacon is at x={bx}, y={by}", line
+            )
+            sensor_to_beacon[int(r["sx"]), int(r["sy"])] = (int(r["bx"]), int(r["by"]))
 
-    m = Model()
+        xy_max = 4_000_000 if max(sensor_to_beacon) > (1_000, 0) else 20
+        row = 2_000_000 if max(sensor_to_beacon) > (1_000, 0) else 10
 
-    x, y = m.continuous_var_list(2, ub=xy_max, name=["x", "y"])
+        yield self.part1(sensor_to_beacon, row)
 
-    for (sx, sy), (bx, by) in sensor_to_beacon.items():
-        d = abs(sx - bx) + abs(sy - by)
-        m.add_constraint(m.abs(x - sx) + m.abs(y - sy) >= d + 1, ctname=f"ct_{sx}_{sy}")  # type: ignore
-
-    m.set_objective("min", x + y)
-
-    s = m.solve()
-    assert s is not None
-
-    vx = int(s.get_value(x))
-    vy = int(s.get_value(y))
-    return vx, vy, 4_000_000 * vx + vy
-
-
-lines = sys.stdin.read().splitlines()
-
-sensor_to_beacon: dict[tuple[int, int], tuple[int, int]] = {}
-
-for line in lines:
-    r: dict[str, str] = parse.parse(  # type: ignore
-        "Sensor at x={sx}, y={sy}: closest beacon is at x={bx}, y={by}", line
-    )
-    sensor_to_beacon[int(r["sx"]), int(r["sy"])] = (int(r["bx"]), int(r["by"]))
-
-xy_max = 4_000_000 if max(sensor_to_beacon) > (1_000, 0) else 20
-row = 2_000_000 if max(sensor_to_beacon) > (1_000, 0) else 10
-
-print(f"answer 1 is {part1(sensor_to_beacon, row)}")
-
-# x, y, a2 = part2_cplex(sensor_to_beacon, xy_max)
-x, y, a2 = part2_intervals(sensor_to_beacon, xy_max)
-print(f"answer 2 is {a2} (x={x}, y={y})")
+        # x, y, a2 = part2_cplex(sensor_to_beacon, xy_max)
+        x, y, a2 = self.part2_intervals(sensor_to_beacon, xy_max)
+        self.logger.info("answer 2 is {at} (x={x}, y={y})")
+        yield a2
diff --git a/src/holt59/aoc/__main__.py b/src/holt59/aoc/__main__.py
index 7fba62d..90509b2 100644
--- a/src/holt59/aoc/__main__.py
+++ b/src/holt59/aoc/__main__.py
@@ -2,12 +2,99 @@ import argparse
 import importlib
 import json
 import logging
+import logging.handlers
 import sys
-from datetime import datetime
+from datetime import datetime, timedelta
 from pathlib import Path
+from typing import Any, Iterable, Iterator, Literal, Sequence, TextIO, TypeVar
+
+from tqdm import tqdm
 
 from .base import BaseSolver
 
+_T = TypeVar("_T")
+
+
+def dump_api_message(
+    type: Literal["log", "answer", "progress-start", "progress-step", "progress-end"],
+    content: Any,
+    file: TextIO = sys.stdout,
+):
+    print(
+        json.dumps(
+            {"type": type, "time": datetime.now().isoformat(), "content": content}
+        ),
+        file=file,
+    )
+
+
+class LoggerAPIHandler(logging.Handler):
+    def __init__(self, output: TextIO = sys.stdout):
+        super().__init__()
+        self.output = output
+
+    def emit(self, record: logging.LogRecord):
+        dump_api_message(
+            "log", {"level": record.levelname, "message": record.getMessage()}
+        )
+
+
+class ProgressAPI:
+    def __init__(
+        self,
+        min_step: int = 1,
+        min_time: timedelta = timedelta(milliseconds=100),
+        output: TextIO = sys.stdout,
+    ):
+        super().__init__()
+
+        self.counter = 0
+        self.output = output
+        self.min_step = min_step
+        self.min_time = min_time
+
+    def wrap(
+        self, values: Sequence[_T] | Iterable[_T], total: int | None = None
+    ) -> Iterator[_T]:
+        total = total or len(values)  # type: ignore
+
+        current = self.counter
+        self.counter += 1
+
+        dump_api_message("progress-start", {"counter": current, "total": total})
+
+        try:
+            percent = 0
+            time = datetime.now()
+
+            for i_value, value in enumerate(values):
+                yield value
+
+                if datetime.now() - time < self.min_time:
+                    continue
+
+                time = datetime.now()
+
+                c_percent = round(i_value / total * 100)
+
+                if c_percent >= percent + self.min_step:
+                    dump_api_message(
+                        "progress-step", {"counter": current, "percent": c_percent}
+                    )
+                    percent = c_percent
+        finally:
+            dump_api_message(
+                "progress-end",
+                {"counter": current},
+            )
+
+
+class ProgressTQDM:
+    def wrap(
+        self, values: Sequence[_T] | Iterable[_T], total: int | None = None
+    ) -> Iterator[_T]:
+        return iter(tqdm(values, total=total))
+
 
 def main():
     parser = argparse.ArgumentParser("Holt59 Advent-Of-Code Runner")
@@ -46,7 +133,10 @@ def main():
     day: int = args.day
 
     # TODO: change this
-    logging.basicConfig(level=logging.INFO if verbose else logging.WARNING)
+    logging.basicConfig(
+        level=logging.INFO if verbose or api else logging.WARNING,
+        handlers=[LoggerAPIHandler()] if api else None,
+    )
 
     if input_path is None:
         input_path = Path(__file__).parent.joinpath(
@@ -59,7 +149,12 @@ def main():
     ).Solver
 
     solver = solver_class(
-        logging.getLogger("AOC"), verbose=verbose, year=year, day=day, outputs=not api
+        logging.getLogger("AOC"),
+        verbose=verbose,
+        year=year,
+        day=day,
+        progress=ProgressAPI() if api else ProgressTQDM(),  # type: ignore
+        outputs=not api,
     )
 
     data: str
@@ -78,6 +173,7 @@ def main():
             print(
                 json.dumps(
                     {
+                        "type": "answer",
                         "answer": i_answer + 1,
                         "value": answer,
                         "answerTime_s": (current - last).total_seconds(),
diff --git a/src/holt59/aoc/base.py b/src/holt59/aoc/base.py
index 45893d2..97cb666 100644
--- a/src/holt59/aoc/base.py
+++ b/src/holt59/aoc/base.py
@@ -1,16 +1,33 @@
 from abc import abstractmethod
 from logging import Logger
-from typing import Any, Final, Iterator
+from typing import Any, Final, Iterable, Iterator, Protocol, Sequence, TypeVar, overload
+
+_T = TypeVar("_T")
+
+
+class ProgressHandler(Protocol):
+    @overload
+    def wrap(self, values: Sequence[_T]) -> Iterator[_T]: ...
+
+    @overload
+    def wrap(self, values: Iterable[_T], total: int) -> Iterator[_T]: ...
 
 
 class BaseSolver:
     def __init__(
-        self, logger: Logger, verbose: bool, year: int, day: int, outputs: bool = False
+        self,
+        logger: Logger,
+        verbose: bool,
+        year: int,
+        day: int,
+        progress: ProgressHandler,
+        outputs: bool = False,
     ):
         self.logger: Final = logger
         self.verbose: Final = verbose
         self.year: Final = year
         self.day: Final = day
+        self.progress: Final = progress
         self.outputs = outputs
 
     @abstractmethod