feat(2-6): stateful Renderer, DisplayInterface, and pipeline smoke test

Implements story 2-6: Renderer class with per-aircraft trail history
(deque capped at TRAIL_MAX_DOTS=5), NullDisplay with DEBUG logging,
WaveshareDisplay stub, and end-to-end pipeline smoke test. All 96
tests pass; ruff check and format clean.

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

_bmad-output/implementation-artifacts/2-6-stateful-renderer-and-display-interface.md

@@ -1,6 +1,6 @@
 # Story 2.6: Stateful Renderer & Display Interface
 
-Status: ready-for-dev
+Status: review
 
 ## Story
 
@@ -22,22 +22,22 @@ AC5: **Given** the `test_pipeline.py` smoke test (`FileFixtureFetcher → Render
 
 ## Tasks / Subtasks
 
-- [ ] Task 1: Update `NullDisplay` in `src/planemapper/display.py` (AC: #4)
-  - [ ] 1.1 Add `import logging` and `log = logging.getLogger(__name__)`
-  - [ ] 1.2 Update `NullDisplay.show()` to log at DEBUG level:
+- [x] Task 1: Update `NullDisplay` in `src/planemapper/display.py` (AC: #4)
+  - [x] 1.1 Add `import logging` and `log = logging.getLogger(__name__)`
+  - [x] 1.2 Update `NullDisplay.show()` to log at DEBUG level:
     ```python
     log.debug("NullDisplay.show: %dx%d", image.width, image.height)
     ```
-  - [ ] 1.3 Add `WaveshareDisplay` stub:
+  - [x] 1.3 Add `WaveshareDisplay` stub:
     ```python
     class WaveshareDisplay:
         def show(self, image: Image.Image) -> None:
             raise NotImplementedError
     ```
 
-- [ ] Task 2: Implement `Renderer` in `src/planemapper/renderer/renderer.py` (AC: #1, #2, #3)
-  - [ ] 2.1 Replace `# stub` with full implementation
-  - [ ] 2.2 Imports:
+- [x] Task 2: Implement `Renderer` in `src/planemapper/renderer/renderer.py` (AC: #1, #2, #3)
+  - [x] 2.1 Replace `# stub` with full implementation
+  - [x] 2.2 Imports:
     ```python
     import collections
     from PIL import Image
@@ -48,7 +48,7 @@ AC5: **Given** the `test_pipeline.py` smoke test (`FileFixtureFetcher → Render
     from planemapper.renderer.overlay import draw_home_marker
     from planemapper.renderer.aircraft import draw_aircraft
     ```
-  - [ ] 2.3 Implement `__init__` with `base_map`, `bounds`, `_trails` dict:
+  - [x] 2.3 Implement `__init__` with `base_map`, `bounds`, `_trails` dict:
     ```python
     def __init__(
         self,
@@ -59,7 +59,7 @@ AC5: **Given** the `test_pipeline.py` smoke test (`FileFixtureFetcher → Render
         self._bounds = bounds
         self._trails: dict[str, collections.deque[tuple[int, int]]] = {}
     ```
-  - [ ] 2.4 Implement `render(aircraft_list)` with full pipeline:
+  - [x] 2.4 Implement `render(aircraft_list)` with full pipeline:
     ```python
     def render(self, aircraft_list: list[Aircraft]) -> Image.Image:
         image = self._base_map.copy()
@@ -76,14 +76,14 @@ AC5: **Given** the `test_pipeline.py` smoke test (`FileFixtureFetcher → Render
         return image
     ```
 
-- [ ] Task 3: Write tests in `tests/test_renderer.py` (AC: #1, #2, #3)
-  - [ ] 3.1 Replace placeholder with full test module
-  - [ ] 3.2 Test AC1: create white 800×480 RGB base map, call `render([])` with empty aircraft list, assert returned image is `PIL.Image.Image` with size `(800, 480)`
-  - [ ] 3.3 Test AC2: call `render()` twice with same aircraft; after second call, assert `renderer._trails` has an entry keyed on the aircraft's ICAO
-  - [ ] 3.4 Test AC3: call `render()` with one aircraft, then call `render([])` with empty list; assert `renderer._trails` still has the aircraft ICAO entry
+- [x] Task 3: Write tests in `tests/test_renderer.py` (AC: #1, #2, #3)
+  - [x] 3.1 Replace placeholder with full test module
+  - [x] 3.2 Test AC1: create white 800×480 RGB base map, call `render([])` with empty aircraft list, assert returned image is `PIL.Image.Image` with size `(800, 480)`
+  - [x] 3.3 Test AC2: call `render()` twice with same aircraft; after second call, assert `renderer._trails` has an entry keyed on the aircraft's ICAO
+  - [x] 3.4 Test AC3: call `render()` with one aircraft, then call `render([])` with empty list; assert `renderer._trails` still has the aircraft ICAO entry
 
-- [ ] Task 4: Write/update pipeline smoke test in `tests/test_pipeline.py` (AC: #5)
-  - [ ] 4.1 Replace placeholder with full smoke test:
+- [x] Task 4: Write/update pipeline smoke test in `tests/test_pipeline.py` (AC: #5)
+  - [x] 4.1 Replace placeholder with full smoke test:
     - Use `FileFixtureFetcher(Path("tests/fixtures/aircraft_sample.json"))`
     - Create a fake 800×480 white RGB base map (`Image.new("RGB", (800, 480), "white")`)
     - Create `Renderer(base_map, bounds)` where `bounds = MapBounds(53.0, -6.0, 100.0)`
@@ -91,12 +91,12 @@ AC5: **Given** the `test_pipeline.py` smoke test (`FileFixtureFetcher → Render
     - Call `renderer.render(fetcher.fetch())`
     - Assert returned image is `PIL.Image.Image` with size `(800, 480)`
     - Call `NullDisplay().show(image)` — assert no exception
-  - [ ] 4.2 Ensure monkeypatch of `AIRSPACE_PATH` is applied before `render()` is called
+  - [x] 4.2 Ensure monkeypatch of `AIRSPACE_PATH` is applied before `render()` is called
 
-- [ ] Task 5: Run quality gates
-  - [ ] 5.1 `python -m pytest tests/` — all tests pass
-  - [ ] 5.2 `python -m ruff check .` — zero violations
-  - [ ] 5.3 `python -m ruff format --check .` — no formatting issues
+- [x] Task 5: Run quality gates
+  - [x] 5.1 `python -m pytest tests/` — all tests pass
+  - [x] 5.2 `python -m ruff check .` — zero violations
+  - [x] 5.3 `python -m ruff format --check .` — no formatting issues
 
 ## Implementation Notes
 

_bmad-output/implementation-artifacts/sprint-status.yaml

@@ -35,7 +35,7 @@
 # - Dev moves story to 'review', then runs code-review (fresh context, different LLM recommended)
 
 generated: 2026-04-22
-last_updated: 2026-04-22  # 2-1 done, 2-2 done, 2-3 done, 2-4 done, 2-5 done, 2-6 ready-for-dev, epic-2 in-progress
+last_updated: 2026-04-22  # 2-1 done, 2-2 done, 2-3 done, 2-4 done, 2-5 done, 2-6 review, epic-2 in-progress
 project: planeMapper
 project_key: NOKEY
 tracking_system: file-system
@@ -58,7 +58,7 @@ development_status:
   2-3-home-marker-and-airspace-outlines: done
   2-4-altitude-colour-bands-and-aircraft-type-icons: done
   2-5-per-aircraft-drawing: done
-  2-6-stateful-renderer-and-display-interface: ready-for-dev
+  2-6-stateful-renderer-and-display-interface: review
   2-7-operational-radar-loop-startup-screen-and-systemd-wiring: backlog
   epic-2-retrospective: optional
 

src/planemapper/display.py

@@ -1,7 +1,12 @@
+from __future__ import annotations
+
+import logging
 from typing import Protocol
 
 from PIL import Image
 
+log = logging.getLogger(__name__)
+
 
 class DisplayInterface(Protocol):
     def show(self, image: Image.Image) -> None: ...
@@ -9,4 +14,9 @@ class DisplayInterface(Protocol):
 
 class NullDisplay:
     def show(self, image: Image.Image) -> None:
-        pass
+        log.debug("NullDisplay.show: %dx%d", image.width, image.height)
+
+
+class WaveshareDisplay:
+    def show(self, image: Image.Image) -> None:
+        raise NotImplementedError

src/planemapper/renderer/renderer.py

@@ -1 +1,33 @@
-# stub
+from __future__ import annotations
+
+import collections
+
+from PIL import Image
+
+from planemapper.constants import TRAIL_MAX_DOTS
+from planemapper.models import Aircraft
+from planemapper.renderer.aircraft import draw_aircraft
+from planemapper.renderer.airspace import draw_airspace
+from planemapper.renderer.overlay import draw_home_marker
+from planemapper.renderer.projection import MapBounds, project
+
+
+class Renderer:
+    def __init__(self, base_map: Image.Image, bounds: MapBounds) -> None:
+        self._base_map = base_map
+        self._bounds = bounds
+        self._trails: dict[str, collections.deque[tuple[int, int]]] = {}
+
+    def render(self, aircraft_list: list[Aircraft]) -> Image.Image:
+        image = self._base_map.copy()
+        draw_airspace(image, self._bounds)
+        draw_home_marker(image, self._bounds)
+        for aircraft in aircraft_list:
+            pos = project(aircraft.lat, aircraft.lon, self._bounds)
+            trail = self._trails.get(aircraft.icao, collections.deque())
+            draw_aircraft(image, aircraft, pos, trail)
+            trail.appendleft(pos)
+            while len(trail) > TRAIL_MAX_DOTS:
+                trail.pop()
+            self._trails[aircraft.icao] = trail
+        return image

tests/test_pipeline.py

@@ -1,2 +1,32 @@
-def test_placeholder() -> None:
-    pass
+from __future__ import annotations
+
+import pathlib
+
+import pytest
+from PIL import Image
+
+from planemapper.display import NullDisplay
+from planemapper.fetcher import FileFixtureFetcher
+from planemapper.renderer.projection import MapBounds
+from planemapper.renderer.renderer import Renderer
+
+FIXTURE_DIR = pathlib.Path(__file__).parent / "fixtures"
+
+
+def test_full_pipeline_smoke(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(
+        "planemapper.renderer.airspace.AIRSPACE_PATH",
+        FIXTURE_DIR / "airspace_sample.geojson",
+    )
+    base_map = Image.new("RGB", (800, 480), color=(255, 255, 255))
+    bounds = MapBounds(home_lat=53.0, home_lon=-6.0, radius_nm=100.0)
+    fetcher = FileFixtureFetcher(FIXTURE_DIR / "aircraft_sample.json")
+    renderer = Renderer(base_map, bounds)
+    display = NullDisplay()
+
+    aircraft_list = fetcher.fetch()
+    result = renderer.render(aircraft_list)
+
+    assert isinstance(result, Image.Image)
+    assert result.size == (800, 480)
+    display.show(result)  # should not raise

tests/test_renderer.py

@@ -1,2 +1,61 @@
-def test_placeholder() -> None:
-    pass
+from __future__ import annotations
+
+import pathlib
+
+import pytest
+from PIL import Image
+
+from planemapper.models import Aircraft
+from planemapper.renderer.projection import MapBounds
+from planemapper.renderer.renderer import Renderer
+
+FIXTURE_DIR = pathlib.Path(__file__).parent / "fixtures"
+
+
+@pytest.fixture
+def white_base_map() -> Image.Image:
+    return Image.new("RGB", (800, 480), color=(255, 255, 255))
+
+
+@pytest.fixture
+def bounds() -> MapBounds:
+    return MapBounds(home_lat=53.0, home_lon=-6.0, radius_nm=100.0)
+
+
+@pytest.fixture
+def renderer(
+    white_base_map: Image.Image, bounds: MapBounds, monkeypatch: pytest.MonkeyPatch
+) -> Renderer:
+    monkeypatch.setattr(
+        "planemapper.renderer.airspace.AIRSPACE_PATH",
+        FIXTURE_DIR / "airspace_sample.geojson",
+    )
+    return Renderer(white_base_map, bounds)
+
+
+def _aircraft(icao: str = "ABC123", **kwargs) -> Aircraft:
+    defaults = {"lat": 53.1, "lon": -6.1}
+    defaults.update(kwargs)
+    return Aircraft(icao=icao, **defaults)
+
+
+def test_render_returns_800x480(renderer: Renderer) -> None:
+    result = renderer.render([])
+    assert isinstance(result, Image.Image)
+    assert result.size == (800, 480)
+
+
+def test_trail_accumulated_across_renders(renderer: Renderer) -> None:
+    ac = _aircraft(icao="ABC123")
+    renderer.render([ac])
+    renderer.render([ac])
+    assert "ABC123" in renderer._trails
+    assert len(renderer._trails["ABC123"]) == 2
+
+
+def test_absent_aircraft_trail_retained(renderer: Renderer) -> None:
+    ac = _aircraft(icao="ABC123")
+    renderer.render([ac])
+    renderer.render([])  # aircraft absent
+    assert "ABC123" in renderer._trails
+    assert len(renderer._trails["ABC123"]) == 1