refactor: Make EffectPlugin an abstract base class, update effects to inherit from it, and improve plugin discovery.

Reviewed-on: #31

AGENTS.md

@@ -0,0 +1,110 @@
+# Agent Development Guide
+
+## Development Environment
+
+This project uses:
+- **mise** (mise.jdx.dev) - tool version manager and task runner
+- **hk** (hk.jdx.dev) - git hook manager
+- **uv** - fast Python package installer
+- **ruff** - linter and formatter
+- **pytest** - test runner
+
+### Setup
+
+```bash
+# Install dependencies
+mise run install
+
+# Or equivalently:
+uv sync
+```
+
+### Available Commands
+
+```bash
+mise run test       # Run tests
+mise run test-v     # Run tests verbose
+mise run test-cov   # Run tests with coverage report
+mise run lint       # Run ruff linter
+mise run lint-fix   # Run ruff with auto-fix
+mise run format     # Run ruff formatter
+mise run ci         # Full CI pipeline (sync + test + coverage)
+```
+
+## Git Hooks
+
+**At the start of every agent session**, verify hooks are installed:
+
+```bash
+ls -la .git/hooks/pre-commit
+```
+
+If hooks are not installed, install them with:
+
+```bash
+hk init --mise
+mise run pre-commit
+```
+
+The project uses hk configured in `hk.pkl`:
+- **pre-commit**: runs ruff-format and ruff (with auto-fix)
+- **pre-push**: runs ruff check
+
+## Workflow Rules
+
+### Before Committing
+
+1. **Always run the test suite** - never commit code that fails tests:
+   ```bash
+   mise run test
+   ```
+
+2. **Always run the linter**:
+   ```bash
+   mise run lint
+   ```
+
+3. **Fix any lint errors** before committing (or let the pre-commit hook handle it).
+
+4. **Review your changes** using `git diff` to understand what will be committed.
+
+### On Failing Tests
+
+When tests fail, **determine whether it's an out-of-date test or a correctly failing test**:
+
+- **Out-of-date test**: The test was written for old behavior that has legitimately changed. Update the test to match the new expected behavior.
+
+- **Correctly failing test**: The test correctly identifies a broken contract. Fix the implementation, not the test.
+
+**Never** modify a test to make it pass without understanding why it failed.
+
+### Code Review
+
+Before committing significant changes:
+- Run `git diff` to review all changes
+- Ensure new code follows existing patterns in the codebase
+- Check that type hints are added for new functions
+- Verify that tests exist for new functionality
+
+## Testing
+
+Tests live in `tests/` and follow the pattern `test_*.py`.
+
+Run all tests:
+```bash
+mise run test
+```
+
+Run with coverage:
+```bash
+mise run test-cov
+```
+
+The project uses pytest with strict marker enforcement. Test configuration is in `pyproject.toml` under `[tool.pytest.ini_options]`.
+
+## Architecture Notes
+
+- **ntfy.py** and **mic.py** are standalone modules with zero internal dependencies
+- **eventbus.py** provides thread-safe event publishing for decoupled communication
+- **controller.py** coordinates ntfy/mic monitoring
+- The render pipeline: fetch → render → effects → scroll → terminal output

README.md

@@ -116,6 +116,8 @@ Update `NTFY_TOPIC` in `engine/config.py` to point at your own topic.
 
 ```
 engine/
+  __init__.py       package marker
+  app.py            main(), font picker TUI, boot sequence, signal handler
   config.py         constants, CLI flags, glyph tables
   sources.py        FEEDS, POETRY_SOURCES, language/script maps
   terminal.py       ANSI codes, tw/th, type_out, boot_ln
@@ -127,15 +129,14 @@ engine/
   ntfy.py           NtfyPoller — standalone, zero internal deps
   mic.py            MicMonitor — standalone, graceful fallback
   scroll.py         stream() frame loop + message rendering
-  app.py          main(), font picker TUI, boot sequence, signal handler
-
-tests/
-  test_config.py
-  test_filter.py
-  test_mic.py
-  test_ntfy.py
-  test_sources.py
-  test_terminal.py
+  viewport.py       terminal dimension tracking (tw/th)
+  frame.py          scroll step calculation, timing
+  layers.py         ticker zone, firehose, message overlay rendering
+  eventbus.py       thread-safe event publishing for decoupled communication
+  events.py         event types and definitions
+  controller.py     coordinates ntfy/mic monitoring and event publishing
+  emitters.py       background emitters for ntfy and mic
+  types.py          type definitions and dataclasses
 ```
 
 `ntfy.py` and `mic.py` have zero internal dependencies and can be imported by any other visualizer.

cmdline.py

@@ -0,0 +1,250 @@
+#!/usr/bin/env python3
+"""
+Command-line utility for interacting with mainline via ntfy.
+
+Usage:
+    python cmdline.py                     # Interactive TUI mode
+    python cmdline.py --help              # Show help
+    python cmdline.py /effects list       # Send single command via ntfy
+    python cmdline.py /effects stats      # Get performance stats via ntfy
+    python cmdline.py -w /effects stats   # Watch mode (polls for stats)
+
+The TUI mode provides:
+    - Arrow keys to navigate command history
+    - Tab completion for commands
+    - Auto-refresh for performance stats
+
+C&C works like a serial port:
+    1. Send command to ntfy_cc_topic
+    2. Mainline receives, processes, responds to same topic
+    3. Cmdline polls for response
+"""
+
+import argparse
+import json
+import sys
+import time
+import threading
+import urllib.request
+from pathlib import Path
+
+from engine import config
+from engine.terminal import CLR, CURSOR_OFF, CURSOR_ON, G_DIM, G_HI, RST, W_GHOST
+
+try:
+    CC_CMD_TOPIC = config.NTFY_CC_CMD_TOPIC
+    CC_RESP_TOPIC = config.NTFY_CC_RESP_TOPIC
+except AttributeError:
+    CC_CMD_TOPIC = "https://ntfy.sh/klubhaus_terminal_mainline_cc_cmd/json"
+    CC_RESP_TOPIC = "https://ntfy.sh/klubhaus_terminal_mainline_cc_resp/json"
+
+
+class NtfyResponsePoller:
+    """Polls ntfy for command responses."""
+
+    def __init__(self, cmd_topic: str, resp_topic: str, timeout: float = 10.0):
+        self.cmd_topic = cmd_topic
+        self.resp_topic = resp_topic
+        self.timeout = timeout
+        self._last_id = None
+        self._lock = threading.Lock()
+
+    def _build_url(self) -> str:
+        from urllib.parse import parse_qs, urlencode, urlparse, urlunparse
+
+        parsed = urlparse(self.resp_topic)
+        params = parse_qs(parsed.query, keep_blank_values=True)
+        params["since"] = [self._last_id if self._last_id else "20s"]
+        new_query = urlencode({k: v[0] for k, v in params.items()})
+        return urlunparse(parsed._replace(query=new_query))
+
+    def send_and_wait(self, cmd: str) -> str:
+        """Send command and wait for response."""
+        url = self.cmd_topic.replace("/json", "")
+        data = cmd.encode("utf-8")
+
+        req = urllib.request.Request(
+            url,
+            data=data,
+            headers={
+                "User-Agent": "mainline-cmdline/0.1",
+                "Content-Type": "text/plain",
+            },
+            method="POST",
+        )
+
+        try:
+            urllib.request.urlopen(req, timeout=5)
+        except Exception as e:
+            return f"Error sending command: {e}"
+
+        return self._wait_for_response(cmd)
+
+    def _wait_for_response(self, expected_cmd: str = "") -> str:
+        """Poll for response message."""
+        start = time.time()
+        while time.time() - start < self.timeout:
+            try:
+                url = self._build_url()
+                req = urllib.request.Request(
+                    url, headers={"User-Agent": "mainline-cmdline/0.1"}
+                )
+                with urllib.request.urlopen(req, timeout=10) as resp:
+                    for line in resp:
+                        try:
+                            data = json.loads(line.decode("utf-8", errors="replace"))
+                        except json.JSONDecodeError:
+                            continue
+                        if data.get("event") == "message":
+                            self._last_id = data.get("id")
+                            msg = data.get("message", "")
+                            if msg:
+                                return msg
+            except Exception:
+                pass
+            time.sleep(0.5)
+        return "Timeout waiting for response"
+
+
+AVAILABLE_COMMANDS = """Available commands:
+  /effects list          - List all effects and status
+  /effects <name> on    - Enable an effect
+  /effects <name> off   - Disable an effect
+  /effects <name> intensity <0.0-1.0> - Set effect intensity
+  /effects reorder <name1>,<name2>,... - Reorder pipeline
+  /effects stats        - Show performance statistics
+  /help                 - Show this help
+  /quit                 - Exit
+"""
+
+
+def print_header():
+    w = 60
+    print(CLR, end="")
+    print(CURSOR_OFF, end="")
+    print(f"\033[1;1H", end="")
+    print(f"  \033[1;38;5;231m╔{'═' * (w - 6)}╗\033[0m")
+    print(
+        f"  \033[1;38;5;231m║\033[0m \033[1;38;5;82mMAINLINE\033[0m \033[3;38;5;245mCommand Center\033[0m \033[1;38;5;231m  ║\033[0m"
+    )
+    print(f"  \033[1;38;5;231m╚{'═' * (w - 6)}╝\033[0m")
+    print(f"  \033[2;38;5;37mCMD: {CC_CMD_TOPIC.split('/')[-2]}\033[0m")
+    print(f"  \033[2;38;5;37mRESP: {CC_RESP_TOPIC.split('/')[-2]}\033[0m")
+    print()
+
+
+def print_response(response: str, is_error: bool = False) -> None:
+    """Print response with nice formatting."""
+    print()
+    if is_error:
+        print(f"  \033[1;38;5;196m✗ Error\033[0m")
+        print(f"  \033[38;5;196m{'─' * 40}\033[0m")
+    else:
+        print(f"  \033[1;38;5;82m✓ Response\033[0m")
+        print(f"  \033[38;5;37m{'─' * 40}\033[0m")
+
+    for line in response.split("\n"):
+        print(f"  {line}")
+    print()
+
+
+def interactive_mode():
+    """Interactive TUI for sending commands."""
+    import readline
+
+    print_header()
+    poller = NtfyResponsePoller(CC_CMD_TOPIC, CC_RESP_TOPIC)
+
+    print(f"  \033[38;5;245mType /help for commands, /quit to exit\033[0m")
+    print()
+
+    while True:
+        try:
+            cmd = input(f"  \033[1;38;5;82m❯\033[0m {G_HI}").strip()
+        except (EOFError, KeyboardInterrupt):
+            print()
+            break
+
+        if not cmd:
+            continue
+
+        if cmd.startswith("/"):
+            if cmd == "/quit" or cmd == "/exit":
+                print(f"\n  \033[1;38;5;245mGoodbye!{RST}\n")
+                break
+
+            if cmd == "/help":
+                print(f"\n{AVAILABLE_COMMANDS}\n")
+                continue
+
+            print(f"  \033[38;5;245m⟳ Sending to mainline...{RST}")
+            result = poller.send_and_wait(cmd)
+            print_response(result, is_error=result.startswith("Error"))
+        else:
+            print(f"\n  \033[1;38;5;196m⚠ Commands must start with /{RST}\n")
+
+    print(CURSOR_ON, end="")
+    return 0
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Mainline command-line interface",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog=AVAILABLE_COMMANDS,
+    )
+    parser.add_argument(
+        "command",
+        nargs="?",
+        default=None,
+        help="Command to send (e.g., /effects list)",
+    )
+    parser.add_argument(
+        "--watch",
+        "-w",
+        action="store_true",
+        help="Watch mode: continuously poll for stats (Ctrl+C to exit)",
+    )
+
+    args = parser.parse_args()
+
+    if args.command is None:
+        return interactive_mode()
+
+    poller = NtfyResponsePoller(CC_CMD_TOPIC, CC_RESP_TOPIC)
+
+    if args.watch and "/effects stats" in args.command:
+        import signal
+
+        def handle_sigterm(*_):
+            print(f"\n  \033[1;38;5;245mStopped watching{RST}")
+            print(CURSOR_ON, end="")
+            sys.exit(0)
+
+        signal.signal(signal.SIGTERM, handle_sigterm)
+
+        print_header()
+        print(f"  \033[38;5;245mWatching /effects stats (Ctrl+C to exit)...{RST}\n")
+        try:
+            while True:
+                result = poller.send_and_wait(args.command)
+                print(f"\033[2J\033[1;1H", end="")
+                print(
+                    f"  \033[1;38;5;82m❯\033[0m Performance Stats - \033[1;38;5;245m{time.strftime('%H:%M:%S')}{RST}"
+                )
+                print(f"  \033[38;5;37m{'─' * 44}{RST}")
+                for line in result.split("\n"):
+                    print(f"  {line}")
+                time.sleep(2)
+        except KeyboardInterrupt:
+            print(f"\n  \033[1;38;5;245mStopped watching{RST}")
+            return 0
+        return 0
+
+    result = poller.send_and_wait(args.command)
+    print(result)
+    return 0
+
+
+if __name__ == "__main__":
+    main()

effects_plugins/__init__.py

@@ -0,0 +1,36 @@
+from pathlib import Path
+
+PLUGIN_DIR = Path(__file__).parent
+
+
+def discover_plugins():
+    from engine.effects.registry import get_registry
+    from engine.effects.types import EffectPlugin
+
+    registry = get_registry()
+    imported = {}
+
+    for file_path in PLUGIN_DIR.glob("*.py"):
+        if file_path.name.startswith("_"):
+            continue
+        module_name = file_path.stem
+        if module_name in ("base", "types"):
+            continue
+
+        try:
+            module = __import__(f"effects_plugins.{module_name}", fromlist=[""])
+            for attr_name in dir(module):
+                attr = getattr(module, attr_name)
+                if (
+                    isinstance(attr, type)
+                    and issubclass(attr, EffectPlugin)
+                    and attr is not EffectPlugin
+                    and attr_name.endswith("Effect")
+                ):
+                    plugin = attr()
+                    registry.register(plugin)
+                    imported[plugin.name] = plugin
+        except Exception:
+            pass
+
+    return imported

effects_plugins/fade.py

@@ -0,0 +1,58 @@
+import random
+
+from engine.effects.types import EffectConfig, EffectContext, EffectPlugin
+
+
+class FadeEffect(EffectPlugin):
+    name = "fade"
+    config = EffectConfig(enabled=True, intensity=1.0)
+
+    def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
+        if not ctx.ticker_height:
+            return buf
+        result = list(buf)
+        intensity = self.config.intensity
+
+        top_zone = max(1, int(ctx.ticker_height * 0.25))
+        bot_zone = max(1, int(ctx.ticker_height * 0.10))
+
+        for r in range(len(result)):
+            if r >= ctx.ticker_height:
+                continue
+            top_f = min(1.0, r / top_zone) if top_zone > 0 else 1.0
+            bot_f = (
+                min(1.0, (ctx.ticker_height - 1 - r) / bot_zone)
+                if bot_zone > 0
+                else 1.0
+            )
+            row_fade = min(top_f, bot_f) * intensity
+
+            if row_fade < 1.0 and result[r].strip():
+                result[r] = self._fade_line(result[r], row_fade)
+
+        return result
+
+    def _fade_line(self, s: str, fade: float) -> str:
+        if fade >= 1.0:
+            return s
+        if fade <= 0.0:
+            return ""
+        result = []
+        i = 0
+        while i < len(s):
+            if s[i] == "\033" and i + 1 < len(s) and s[i + 1] == "[":
+                j = i + 2
+                while j < len(s) and not s[j].isalpha():
+                    j += 1
+                result.append(s[i : j + 1])
+                i = j + 1
+            elif s[i] == " ":
+                result.append(" ")
+                i += 1
+            else:
+                result.append(s[i] if random.random() < fade else " ")
+                i += 1
+        return "".join(result)
+
+    def configure(self, cfg: EffectConfig) -> None:
+        self.config = cfg

effects_plugins/firehose.py

@@ -0,0 +1,72 @@
+import random
+from datetime import datetime
+
+from engine import config
+from engine.effects.types import EffectConfig, EffectContext, EffectPlugin
+from engine.sources import FEEDS, POETRY_SOURCES
+from engine.terminal import C_DIM, G_DIM, G_LO, RST, W_GHOST
+
+
+class FirehoseEffect(EffectPlugin):
+    name = "firehose"
+    config = EffectConfig(enabled=True, intensity=1.0)
+
+    def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
+        firehose_h = config.FIREHOSE_H if config.FIREHOSE else 0
+        if firehose_h <= 0 or not ctx.items:
+            return buf
+
+        result = list(buf)
+        intensity = self.config.intensity
+        h = ctx.terminal_height
+
+        for fr in range(firehose_h):
+            scr_row = h - firehose_h + fr + 1
+            fline = self._firehose_line(ctx.items, ctx.terminal_width, intensity)
+            result.append(f"\033[{scr_row};1H{fline}\033[K")
+        return result
+
+    def _firehose_line(self, items: list, w: int, intensity: float) -> str:
+        r = random.random()
+        if r < 0.35 * intensity:
+            title, src, ts = random.choice(items)
+            text = title[: w - 1]
+            color = random.choice([G_LO, G_DIM, W_GHOST, C_DIM])
+            return f"{color}{text}{RST}"
+        elif r < 0.55 * intensity:
+            d = random.choice([0.45, 0.55, 0.65, 0.75])
+            return "".join(
+                f"{random.choice([G_LO, G_DIM, C_DIM, W_GHOST])}"
+                f"{random.choice(config.GLITCH + config.KATA)}{RST}"
+                if random.random() < d
+                else " "
+                for _ in range(w)
+            )
+        elif r < 0.78 * intensity:
+            sources = FEEDS if config.MODE == "news" else POETRY_SOURCES
+            src = random.choice(list(sources.keys()))
+            msgs = [
+                f"  SIGNAL :: {src} :: {datetime.now().strftime('%H:%M:%S.%f')[:-3]}",
+                f"  ░░ FEED ACTIVE :: {src}",
+                f"  >> DECODE 0x{random.randint(0x1000, 0xFFFF):04X} :: {src[:24]}",
+                f"  ▒▒ ACQUIRE :: {random.choice(['TCP', 'UDP', 'RSS', 'ATOM', 'XML'])} :: {src}",
+                f"  {''.join(random.choice(config.KATA) for _ in range(3))} STRM "
+                f"{random.randint(0, 255):02X}:{random.randint(0, 255):02X}",
+            ]
+            text = random.choice(msgs)[: w - 1]
+            color = random.choice([G_LO, G_DIM, W_GHOST])
+            return f"{color}{text}{RST}"
+        else:
+            title, _, _ = random.choice(items)
+            start = random.randint(0, max(0, len(title) - 20))
+            frag = title[start : start + random.randint(10, 35)]
+            pad = random.randint(0, max(0, w - len(frag) - 8))
+            gp = "".join(
+                random.choice(config.GLITCH) for _ in range(random.randint(1, 3))
+            )
+            text = (" " * pad + gp + " " + frag)[: w - 1]
+            color = random.choice([G_LO, C_DIM, W_GHOST])
+            return f"{color}{text}{RST}"
+
+    def configure(self, cfg: EffectConfig) -> None:
+        self.config = cfg

effects_plugins/glitch.py

@@ -0,0 +1,37 @@
+import random
+
+from engine import config
+from engine.effects.types import EffectConfig, EffectContext, EffectPlugin
+from engine.terminal import C_DIM, DIM, G_DIM, G_LO, RST
+
+
+class GlitchEffect(EffectPlugin):
+    name = "glitch"
+    config = EffectConfig(enabled=True, intensity=1.0)
+
+    def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
+        if not buf:
+            return buf
+        result = list(buf)
+        intensity = self.config.intensity
+
+        glitch_prob = 0.32 + min(0.9, ctx.mic_excess * 0.16)
+        glitch_prob = glitch_prob * intensity
+        n_hits = 4 + int(ctx.mic_excess / 2)
+        n_hits = int(n_hits * intensity)
+
+        if random.random() < glitch_prob:
+            for _ in range(min(n_hits, len(result))):
+                gi = random.randint(0, len(result) - 1)
+                scr_row = gi + 1
+                result[gi] = f"\033[{scr_row};1H{self._glitch_bar(ctx.terminal_width)}"
+        return result
+
+    def _glitch_bar(self, w: int) -> str:
+        c = random.choice(["░", "▒", "─", "\xc2"])
+        n = random.randint(3, w // 2)
+        o = random.randint(0, w - n)
+        return " " * o + f"{G_LO}{DIM}" + c * n + RST
+
+    def configure(self, cfg: EffectConfig) -> None:
+        self.config = cfg

effects_plugins/noise.py

@@ -0,0 +1,36 @@
+import random
+
+from engine import config
+from engine.effects.types import EffectConfig, EffectContext, EffectPlugin
+from engine.terminal import C_DIM, G_DIM, G_LO, RST, W_GHOST
+
+
+class NoiseEffect(EffectPlugin):
+    name = "noise"
+    config = EffectConfig(enabled=True, intensity=0.15)
+
+    def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
+        if not ctx.ticker_height:
+            return buf
+        result = list(buf)
+        intensity = self.config.intensity
+        probability = intensity * 0.15
+
+        for r in range(len(result)):
+            cy = ctx.scroll_cam + r
+            if random.random() < probability:
+                result[r] = self._generate_noise(ctx.terminal_width, cy)
+        return result
+
+    def _generate_noise(self, w: int, cy: int) -> str:
+        d = random.choice([0.15, 0.25, 0.35, 0.12])
+        return "".join(
+            f"{random.choice([G_LO, G_DIM, C_DIM, W_GHOST])}"
+            f"{random.choice(config.GLITCH + config.KATA)}{RST}"
+            if random.random() < d
+            else " "
+            for _ in range(w)
+        )
+
+    def configure(self, cfg: EffectConfig) -> None:
+        self.config = cfg

engine/config.py

@@ -1,25 +1,28 @@
 """
 Configuration constants, CLI flags, and glyph tables.
+Supports both global constants (backward compatible) and injected config for testing.
 """
 
 import sys
+from dataclasses import dataclass, field
 from pathlib import Path
 
 _REPO_ROOT = Path(__file__).resolve().parent.parent
 _FONT_EXTENSIONS = {".otf", ".ttf", ".ttc"}
 
 
-def _arg_value(flag):
+def _arg_value(flag, argv: list[str] | None = None):
     """Get value following a CLI flag, if present."""
-    if flag not in sys.argv:
+    argv = argv or sys.argv
+    if flag not in argv:
         return None
-    i = sys.argv.index(flag)
-    return sys.argv[i + 1] if i + 1 < len(sys.argv) else None
+    i = argv.index(flag)
+    return argv[i + 1] if i + 1 < len(argv) else None
 
 
-def _arg_int(flag, default):
+def _arg_int(flag, default, argv: list[str] | None = None):
     """Get int CLI argument with safe fallback."""
-    raw = _arg_value(flag)
+    raw = _arg_value(flag, argv)
     if raw is None:
         return default
     try:
@@ -53,6 +56,134 @@ def list_repo_font_files():
     return _list_font_files(FONT_DIR)
 
 
+def _get_platform_font_paths() -> dict[str, str]:
+    """Get platform-appropriate font paths for non-Latin scripts."""
+    import platform
+
+    system = platform.system()
+
+    if system == "Darwin":
+        return {
+            "zh-cn": "/System/Library/Fonts/STHeiti Medium.ttc",
+            "ja": "/System/Library/Fonts/ヒラギノ角ゴシック W9.ttc",
+            "ko": "/System/Library/Fonts/AppleSDGothicNeo.ttc",
+            "ru": "/System/Library/Fonts/Supplemental/Arial.ttf",
+            "uk": "/System/Library/Fonts/Supplemental/Arial.ttf",
+            "el": "/System/Library/Fonts/Supplemental/Arial.ttf",
+            "he": "/System/Library/Fonts/Supplemental/Arial.ttf",
+            "ar": "/System/Library/Fonts/GeezaPro.ttc",
+            "fa": "/System/Library/Fonts/GeezaPro.ttc",
+            "hi": "/System/Library/Fonts/Kohinoor.ttc",
+            "th": "/System/Library/Fonts/ThonburiUI.ttc",
+        }
+    elif system == "Linux":
+        return {
+            "zh-cn": "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc",
+            "ja": "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc",
+            "ko": "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc",
+            "ru": "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
+            "uk": "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
+            "el": "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
+            "he": "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
+            "ar": "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
+            "fa": "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
+            "hi": "/usr/share/fonts/truetype/noto/NotoSansDevanagari-Regular.ttf",
+            "th": "/usr/share/fonts/truetype/noto/NotoSansThai-Regular.ttf",
+        }
+    else:
+        return {}
+
+
+@dataclass(frozen=True)
+class Config:
+    """Immutable configuration container for injected config."""
+
+    headline_limit: int = 1000
+    feed_timeout: int = 10
+    mic_threshold_db: int = 50
+    mode: str = "news"
+    firehose: bool = False
+
+    ntfy_topic: str = "https://ntfy.sh/klubhaus_terminal_mainline/json"
+    ntfy_reconnect_delay: int = 5
+    message_display_secs: int = 30
+
+    font_dir: str = "fonts"
+    font_path: str = ""
+    font_index: int = 0
+    font_picker: bool = True
+    font_sz: int = 60
+    render_h: int = 8
+
+    ssaa: int = 4
+
+    scroll_dur: float = 5.625
+    frame_dt: float = 0.05
+    firehose_h: int = 12
+    grad_speed: float = 0.08
+
+    glitch_glyphs: str = "░▒▓█▌▐╌╍╎╏┃┆┇┊┋"
+    kata_glyphs: str = "ﾊﾐﾋｰｳｼﾅﾓﾆｻﾜﾂｵﾘｱﾎﾃﾏｹﾒｴｶｷﾑﾕﾗｾﾈｽﾀﾇﾍ"
+
+    script_fonts: dict[str, str] = field(default_factory=_get_platform_font_paths)
+
+    @classmethod
+    def from_args(cls, argv: list[str] | None = None) -> "Config":
+        """Create Config from CLI arguments (or custom argv for testing)."""
+        argv = argv or sys.argv
+
+        font_dir = _resolve_font_path(_arg_value("--font-dir", argv) or "fonts")
+        font_file_arg = _arg_value("--font-file", argv)
+        font_files = _list_font_files(font_dir)
+        font_path = (
+            _resolve_font_path(font_file_arg)
+            if font_file_arg
+            else (font_files[0] if font_files else "")
+        )
+
+        return cls(
+            headline_limit=1000,
+            feed_timeout=10,
+            mic_threshold_db=50,
+            mode="poetry" if "--poetry" in argv or "-p" in argv else "news",
+            firehose="--firehose" in argv,
+            ntfy_topic="https://ntfy.sh/klubhaus_terminal_mainline/json",
+            ntfy_reconnect_delay=5,
+            message_display_secs=30,
+            font_dir=font_dir,
+            font_path=font_path,
+            font_index=max(0, _arg_int("--font-index", 0, argv)),
+            font_picker="--no-font-picker" not in argv,
+            font_sz=60,
+            render_h=8,
+            ssaa=4,
+            scroll_dur=5.625,
+            frame_dt=0.05,
+            firehose_h=12,
+            grad_speed=0.08,
+            glitch_glyphs="░▒▓█▌▐╌╍╎╏┃┆┇┊┋",
+            kata_glyphs="ﾊﾐﾋｰｳｼﾅﾓﾆｻﾜﾂｵﾘｱﾎﾃﾏｹﾒｴｶｷﾑﾕﾗｾﾈｽﾀﾇﾍ",
+            script_fonts=_get_platform_font_paths(),
+        )
+
+
+_config: Config | None = None
+
+
+def get_config() -> Config:
+    """Get the global config instance (lazy-loaded)."""
+    global _config
+    if _config is None:
+        _config = Config.from_args()
+    return _config
+
+
+def set_config(config: Config) -> None:
+    """Set the global config instance (for testing)."""
+    global _config
+    _config = config
+
+
 # ─── RUNTIME ──────────────────────────────────────────────
 HEADLINE_LIMIT = 1000
 FEED_TIMEOUT = 10

engine/controller.py

@@ -0,0 +1,68 @@
+"""
+Stream controller - manages input sources and orchestrates the render stream.
+"""
+
+from engine.config import Config, get_config
+from engine.eventbus import EventBus
+from engine.events import EventType, StreamEvent
+from engine.mic import MicMonitor
+from engine.ntfy import NtfyPoller
+from engine.scroll import stream
+
+
+class StreamController:
+    """Controls the stream lifecycle - initializes sources and runs the stream."""
+
+    def __init__(self, config: Config | None = None, event_bus: EventBus | None = None):
+        self.config = config or get_config()
+        self.event_bus = event_bus
+        self.mic: MicMonitor | None = None
+        self.ntfy: NtfyPoller | None = None
+
+    def initialize_sources(self) -> tuple[bool, bool]:
+        """Initialize microphone and ntfy sources.
+
+        Returns:
+            (mic_ok, ntfy_ok) - success status for each source
+        """
+        self.mic = MicMonitor(threshold_db=self.config.mic_threshold_db)
+        mic_ok = self.mic.start() if self.mic.available else False
+
+        self.ntfy = NtfyPoller(
+            self.config.ntfy_topic,
+            reconnect_delay=self.config.ntfy_reconnect_delay,
+            display_secs=self.config.message_display_secs,
+        )
+        ntfy_ok = self.ntfy.start()
+
+        return bool(mic_ok), ntfy_ok
+
+    def run(self, items: list) -> None:
+        """Run the stream with initialized sources."""
+        if self.mic is None or self.ntfy is None:
+            self.initialize_sources()
+
+        if self.event_bus:
+            self.event_bus.publish(
+                EventType.STREAM_START,
+                StreamEvent(
+                    event_type=EventType.STREAM_START,
+                    headline_count=len(items),
+                ),
+            )
+
+        stream(items, self.ntfy, self.mic)
+
+        if self.event_bus:
+            self.event_bus.publish(
+                EventType.STREAM_END,
+                StreamEvent(
+                    event_type=EventType.STREAM_END,
+                    headline_count=len(items),
+                ),
+            )
+
+    def cleanup(self) -> None:
+        """Clean up resources."""
+        if self.mic:
+            self.mic.stop()

engine/display.py

@@ -0,0 +1,102 @@
+"""
+Display output abstraction - allows swapping output backends.
+
+Protocol:
+    - init(width, height): Initialize display with terminal dimensions
+    - show(buffer): Render buffer (list of strings) to display
+    - clear(): Clear the display
+    - cleanup(): Shutdown display
+"""
+
+import time
+from typing import Protocol
+
+
+class Display(Protocol):
+    """Protocol for display backends."""
+
+    def init(self, width: int, height: int) -> None:
+        """Initialize display with dimensions."""
+        ...
+
+    def show(self, buffer: list[str]) -> None:
+        """Show buffer on display."""
+        ...
+
+    def clear(self) -> None:
+        """Clear display."""
+        ...
+
+    def cleanup(self) -> None:
+        """Shutdown display."""
+        ...
+
+
+def get_monitor():
+    """Get the performance monitor."""
+    try:
+        from engine.effects.performance import get_monitor as _get_monitor
+
+        return _get_monitor()
+    except Exception:
+        return None
+
+
+class TerminalDisplay:
+    """ANSI terminal display backend."""
+
+    def __init__(self):
+        self.width = 80
+        self.height = 24
+
+    def init(self, width: int, height: int) -> None:
+        from engine.terminal import CURSOR_OFF
+
+        self.width = width
+        self.height = height
+        print(CURSOR_OFF, end="", flush=True)
+
+    def show(self, buffer: list[str]) -> None:
+        import sys
+
+        t0 = time.perf_counter()
+        sys.stdout.buffer.write("".join(buffer).encode())
+        sys.stdout.flush()
+        elapsed_ms = (time.perf_counter() - t0) * 1000
+
+        monitor = get_monitor()
+        if monitor:
+            chars_in = sum(len(line) for line in buffer)
+            monitor.record_effect("terminal_display", elapsed_ms, chars_in, chars_in)
+
+    def clear(self) -> None:
+        from engine.terminal import CLR
+
+        print(CLR, end="", flush=True)
+
+    def cleanup(self) -> None:
+        from engine.terminal import CURSOR_ON
+
+        print(CURSOR_ON, end="", flush=True)
+
+
+class NullDisplay:
+    """Headless/null display - discards all output."""
+
+    def init(self, width: int, height: int) -> None:
+        self.width = width
+        self.height = height
+
+    def show(self, buffer: list[str]) -> None:
+        monitor = get_monitor()
+        if monitor:
+            t0 = time.perf_counter()
+            chars_in = sum(len(line) for line in buffer)
+            elapsed_ms = (time.perf_counter() - t0) * 1000
+            monitor.record_effect("null_display", elapsed_ms, chars_in, chars_in)
+
+    def clear(self) -> None:
+        pass
+
+    def cleanup(self) -> None:
+        pass

engine/effects/__init__.py

@@ -0,0 +1,42 @@
+from engine.effects.chain import EffectChain
+from engine.effects.controller import handle_effects_command, show_effects_menu
+from engine.effects.legacy import (
+    fade_line,
+    firehose_line,
+    glitch_bar,
+    next_headline,
+    noise,
+    vis_trunc,
+)
+from engine.effects.performance import PerformanceMonitor, get_monitor, set_monitor
+from engine.effects.registry import EffectRegistry, get_registry, set_registry
+from engine.effects.types import EffectConfig, EffectContext, PipelineConfig
+
+
+def get_effect_chain():
+    from engine.layers import get_effect_chain as _chain
+
+    return _chain()
+
+
+__all__ = [
+    "EffectChain",
+    "EffectRegistry",
+    "EffectConfig",
+    "EffectContext",
+    "PipelineConfig",
+    "get_registry",
+    "set_registry",
+    "get_effect_chain",
+    "get_monitor",
+    "set_monitor",
+    "PerformanceMonitor",
+    "handle_effects_command",
+    "show_effects_menu",
+    "fade_line",
+    "firehose_line",
+    "glitch_bar",
+    "noise",
+    "next_headline",
+    "vis_trunc",
+]

engine/effects/chain.py

@@ -0,0 +1,71 @@
+import time
+
+from engine.effects.performance import PerformanceMonitor, get_monitor
+from engine.effects.registry import EffectRegistry
+from engine.effects.types import EffectContext
+
+
+class EffectChain:
+    def __init__(
+        self, registry: EffectRegistry, monitor: PerformanceMonitor | None = None
+    ):
+        self._registry = registry
+        self._order: list[str] = []
+        self._monitor = monitor
+
+    def _get_monitor(self) -> PerformanceMonitor:
+        if self._monitor is not None:
+            return self._monitor
+        return get_monitor()
+
+    def set_order(self, names: list[str]) -> None:
+        self._order = list(names)
+
+    def get_order(self) -> list[str]:
+        return self._order.copy()
+
+    def add_effect(self, name: str, position: int | None = None) -> bool:
+        if name not in self._registry.list_all():
+            return False
+        if position is None:
+            self._order.append(name)
+        else:
+            self._order.insert(position, name)
+        return True
+
+    def remove_effect(self, name: str) -> bool:
+        if name in self._order:
+            self._order.remove(name)
+            return True
+        return False
+
+    def reorder(self, new_order: list[str]) -> bool:
+        all_plugins = set(self._registry.list_all().keys())
+        if not all(name in all_plugins for name in new_order):
+            return False
+        self._order = list(new_order)
+        return True
+
+    def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
+        monitor = self._get_monitor()
+        frame_number = ctx.frame_number
+        monitor.start_frame(frame_number)
+
+        frame_start = time.perf_counter()
+        result = list(buf)
+        for name in self._order:
+            plugin = self._registry.get(name)
+            if plugin and plugin.config.enabled:
+                chars_in = sum(len(line) for line in result)
+                effect_start = time.perf_counter()
+                try:
+                    result = plugin.process(result, ctx)
+                except Exception:
+                    plugin.config.enabled = False
+                elapsed = time.perf_counter() - effect_start
+                chars_out = sum(len(line) for line in result)
+                monitor.record_effect(name, elapsed * 1000, chars_in, chars_out)
+
+        total_elapsed = time.perf_counter() - frame_start
+        monitor.end_frame(frame_number, total_elapsed * 1000)
+        return result

engine/effects/controller.py

@@ -0,0 +1,144 @@
+from engine.effects.performance import get_monitor
+from engine.effects.registry import get_registry
+
+_effect_chain_ref = None
+
+
+def _get_effect_chain():
+    global _effect_chain_ref
+    if _effect_chain_ref is not None:
+        return _effect_chain_ref
+    try:
+        from engine.layers import get_effect_chain as _chain
+
+        return _chain()
+    except Exception:
+        return None
+
+
+def set_effect_chain_ref(chain) -> None:
+    global _effect_chain_ref
+    _effect_chain_ref = chain
+
+
+def handle_effects_command(cmd: str) -> str:
+    """Handle /effects command from NTFY message.
+
+    Commands:
+        /effects list - list all effects and their status
+        /effects <name> on - enable an effect
+        /effects <name> off - disable an effect
+        /effects <name> intensity <0.0-1.0> - set intensity
+        /effects reorder <name1>,<name2>,... - reorder pipeline
+        /effects stats - show performance statistics
+    """
+    parts = cmd.strip().split()
+    if not parts or parts[0] != "/effects":
+        return "Unknown command"
+
+    registry = get_registry()
+    chain = _get_effect_chain()
+
+    if len(parts) == 1 or parts[1] == "list":
+        result = ["Effects:"]
+        for name, plugin in registry.list_all().items():
+            status = "ON" if plugin.config.enabled else "OFF"
+            intensity = plugin.config.intensity
+            result.append(f"  {name}: {status} (intensity={intensity})")
+        if chain:
+            result.append(f"Order: {chain.get_order()}")
+        return "\n".join(result)
+
+    if parts[1] == "stats":
+        return _format_stats()
+
+    if parts[1] == "reorder" and len(parts) >= 3:
+        new_order = parts[2].split(",")
+        if chain and chain.reorder(new_order):
+            return f"Reordered pipeline: {new_order}"
+        return "Failed to reorder pipeline"
+
+    if len(parts) < 3:
+        return "Usage: /effects <name> on|off|intensity <value>"
+
+    effect_name = parts[1]
+    action = parts[2]
+
+    if effect_name not in registry.list_all():
+        return f"Unknown effect: {effect_name}"
+
+    if action == "on":
+        registry.enable(effect_name)
+        return f"Enabled: {effect_name}"
+
+    if action == "off":
+        registry.disable(effect_name)
+        return f"Disabled: {effect_name}"
+
+    if action == "intensity" and len(parts) >= 4:
+        try:
+            value = float(parts[3])
+            if not 0.0 <= value <= 1.0:
+                return "Intensity must be between 0.0 and 1.0"
+            plugin = registry.get(effect_name)
+            if plugin:
+                plugin.config.intensity = value
+                return f"Set {effect_name} intensity to {value}"
+        except ValueError:
+            return "Invalid intensity value"
+
+    return f"Unknown action: {action}"
+
+
+def _format_stats() -> str:
+    monitor = get_monitor()
+    stats = monitor.get_stats()
+
+    if "error" in stats:
+        return stats["error"]
+
+    lines = ["Performance Stats:"]
+
+    pipeline = stats["pipeline"]
+    lines.append(
+        f"  Pipeline: avg={pipeline['avg_ms']:.2f}ms min={pipeline['min_ms']:.2f}ms max={pipeline['max_ms']:.2f}ms (over {stats['frame_count']} frames)"
+    )
+
+    if stats["effects"]:
+        lines.append("  Per-effect (avg ms):")
+        for name, effect_stats in stats["effects"].items():
+            lines.append(
+                f"    {name}: avg={effect_stats['avg_ms']:.2f}ms min={effect_stats['min_ms']:.2f}ms max={effect_stats['max_ms']:.2f}ms"
+            )
+
+    return "\n".join(lines)
+
+
+def show_effects_menu() -> str:
+    """Generate effects menu text for display."""
+    registry = get_registry()
+    chain = _get_effect_chain()
+
+    lines = [
+        "\033[1;38;5;231m=== EFFECTS MENU ===\033[0m",
+        "",
+        "Effects:",
+    ]
+
+    for name, plugin in registry.list_all().items():
+        status = "ON" if plugin.config.enabled else "OFF"
+        intensity = plugin.config.intensity
+        lines.append(f"  [{status:3}] {name}: intensity={intensity:.2f}")
+
+    if chain:
+        lines.append("")
+        lines.append(f"Pipeline order: {' -> '.join(chain.get_order())}")
+
+    lines.append("")
+    lines.append("Controls:")
+    lines.append("  /effects <name> on|off")
+    lines.append("  /effects <name> intensity <0.0-1.0>")
+    lines.append("  /effects reorder name1,name2,...")
+    lines.append("")
+
+    return "\n".join(lines)

engine/effects/performance.py

@@ -0,0 +1,103 @@
+from collections import deque
+from dataclasses import dataclass
+
+
+@dataclass
+class EffectTiming:
+    name: str
+    duration_ms: float
+    buffer_chars_in: int
+    buffer_chars_out: int
+
+
+@dataclass
+class FrameTiming:
+    frame_number: int
+    total_ms: float
+    effects: list[EffectTiming]
+
+
+class PerformanceMonitor:
+    """Collects and stores performance metrics for effect pipeline."""
+
+    def __init__(self, max_frames: int = 60):
+        self._max_frames = max_frames
+        self._frames: deque[FrameTiming] = deque(maxlen=max_frames)
+        self._current_frame: list[EffectTiming] = []
+
+    def start_frame(self, frame_number: int) -> None:
+        self._current_frame = []
+
+    def record_effect(
+        self, name: str, duration_ms: float, chars_in: int, chars_out: int
+    ) -> None:
+        self._current_frame.append(
+            EffectTiming(
+                name=name,
+                duration_ms=duration_ms,
+                buffer_chars_in=chars_in,
+                buffer_chars_out=chars_out,
+            )
+        )
+
+    def end_frame(self, frame_number: int, total_ms: float) -> None:
+        self._frames.append(
+            FrameTiming(
+                frame_number=frame_number,
+                total_ms=total_ms,
+                effects=self._current_frame,
+            )
+        )
+
+    def get_stats(self) -> dict:
+        if not self._frames:
+            return {"error": "No timing data available"}
+
+        total_times = [f.total_ms for f in self._frames]
+        avg_total = sum(total_times) / len(total_times)
+        min_total = min(total_times)
+        max_total = max(total_times)
+
+        effect_stats: dict[str, dict] = {}
+        for frame in self._frames:
+            for effect in frame.effects:
+                if effect.name not in effect_stats:
+                    effect_stats[effect.name] = {"times": [], "total_chars": 0}
+                effect_stats[effect.name]["times"].append(effect.duration_ms)
+                effect_stats[effect.name]["total_chars"] += effect.buffer_chars_out
+
+        for name, stats in effect_stats.items():
+            times = stats["times"]
+            stats["avg_ms"] = sum(times) / len(times)
+            stats["min_ms"] = min(times)
+            stats["max_ms"] = max(times)
+            del stats["times"]
+
+        return {
+            "frame_count": len(self._frames),
+            "pipeline": {
+                "avg_ms": avg_total,
+                "min_ms": min_total,
+                "max_ms": max_total,
+            },
+            "effects": effect_stats,
+        }
+
+    def reset(self) -> None:
+        self._frames.clear()
+        self._current_frame = []
+
+
+_monitor: PerformanceMonitor | None = None
+
+
+def get_monitor() -> PerformanceMonitor:
+    global _monitor
+    if _monitor is None:
+        _monitor = PerformanceMonitor()
+    return _monitor
+
+
+def set_monitor(monitor: PerformanceMonitor) -> None:
+    global _monitor
+    _monitor = monitor

engine/effects/registry.py

@@ -0,0 +1,59 @@
+from engine.effects.types import EffectConfig, EffectPlugin
+
+
+class EffectRegistry:
+    def __init__(self):
+        self._plugins: dict[str, EffectPlugin] = {}
+        self._discovered: bool = False
+
+    def register(self, plugin: EffectPlugin) -> None:
+        self._plugins[plugin.name] = plugin
+
+    def get(self, name: str) -> EffectPlugin | None:
+        return self._plugins.get(name)
+
+    def list_all(self) -> dict[str, EffectPlugin]:
+        return self._plugins.copy()
+
+    def list_enabled(self) -> list[EffectPlugin]:
+        return [p for p in self._plugins.values() if p.config.enabled]
+
+    def enable(self, name: str) -> bool:
+        plugin = self._plugins.get(name)
+        if plugin:
+            plugin.config.enabled = True
+            return True
+        return False
+
+    def disable(self, name: str) -> bool:
+        plugin = self._plugins.get(name)
+        if plugin:
+            plugin.config.enabled = False
+            return True
+        return False
+
+    def configure(self, name: str, config: EffectConfig) -> bool:
+        plugin = self._plugins.get(name)
+        if plugin:
+            plugin.configure(config)
+            return True
+        return False
+
+    def is_enabled(self, name: str) -> bool:
+        plugin = self._plugins.get(name)
+        return plugin.config.enabled if plugin else False
+
+
+_registry: EffectRegistry | None = None
+
+
+def get_registry() -> EffectRegistry:
+    global _registry
+    if _registry is None:
+        _registry = EffectRegistry()
+    return _registry
+
+
+def set_registry(registry: EffectRegistry) -> None:
+    global _registry
+    _registry = registry

engine/effects/types.py

@@ -0,0 +1,68 @@
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from typing import Any
+
+
+@dataclass
+class EffectContext:
+    terminal_width: int
+    terminal_height: int
+    scroll_cam: int
+    ticker_height: int
+    camera_x: int = 0
+    mic_excess: float = 0.0
+    grad_offset: float = 0.0
+    frame_number: int = 0
+    has_message: bool = False
+    items: list = field(default_factory=list)
+
+
+@dataclass
+class EffectConfig:
+    enabled: bool = True
+    intensity: float = 1.0
+    params: dict[str, Any] = field(default_factory=dict)
+
+
+class EffectPlugin(ABC):
+    name: str
+    config: EffectConfig
+
+    @abstractmethod
+    def process(self, buf: list[str], ctx: EffectContext) -> list[str]: ...
+
+    @abstractmethod
+    def configure(self, config: EffectConfig) -> None: ...
+
+
+def create_effect_context(
+    terminal_width: int = 80,
+    terminal_height: int = 24,
+    scroll_cam: int = 0,
+    ticker_height: int = 0,
+    camera_x: int = 0,
+    mic_excess: float = 0.0,
+    grad_offset: float = 0.0,
+    frame_number: int = 0,
+    has_message: bool = False,
+    items: list | None = None,
+) -> EffectContext:
+    """Factory function to create EffectContext with sensible defaults."""
+    return EffectContext(
+        terminal_width=terminal_width,
+        terminal_height=terminal_height,
+        scroll_cam=scroll_cam,
+        ticker_height=ticker_height,
+        camera_x=camera_x,
+        mic_excess=mic_excess,
+        grad_offset=grad_offset,
+        frame_number=frame_number,
+        has_message=has_message,
+        items=items or [],
+    )
+
+
+@dataclass
+class PipelineConfig:
+    order: list[str] = field(default_factory=list)
+    effects: dict[str, EffectConfig] = field(default_factory=dict)

engine/emitters.py

@@ -0,0 +1,25 @@
+"""
+Event emitter protocols - abstract interfaces for event-producing components.
+"""
+
+from collections.abc import Callable
+from typing import Any, Protocol
+
+
+class EventEmitter(Protocol):
+    """Protocol for components that emit events."""
+
+    def subscribe(self, callback: Callable[[Any], None]) -> None: ...
+    def unsubscribe(self, callback: Callable[[Any], None]) -> None: ...
+
+
+class Startable(Protocol):
+    """Protocol for components that can be started."""
+
+    def start(self) -> Any: ...
+
+
+class Stoppable(Protocol):
+    """Protocol for components that can be stopped."""
+
+    def stop(self) -> None: ...

engine/eventbus.py

@@ -0,0 +1,72 @@
+"""
+Event bus - pub/sub messaging for decoupled component communication.
+"""
+
+import threading
+from collections import defaultdict
+from collections.abc import Callable
+from typing import Any
+
+from engine.events import EventType
+
+
+class EventBus:
+    """Thread-safe event bus for publish-subscribe messaging."""
+
+    def __init__(self):
+        self._subscribers: dict[EventType, list[Callable[[Any], None]]] = defaultdict(
+            list
+        )
+        self._lock = threading.Lock()
+
+    def subscribe(self, event_type: EventType, callback: Callable[[Any], None]) -> None:
+        """Register a callback for a specific event type."""
+        with self._lock:
+            self._subscribers[event_type].append(callback)
+
+    def unsubscribe(
+        self, event_type: EventType, callback: Callable[[Any], None]
+    ) -> None:
+        """Remove a callback for a specific event type."""
+        with self._lock:
+            if callback in self._subscribers[event_type]:
+                self._subscribers[event_type].remove(callback)
+
+    def publish(self, event_type: EventType, event: Any = None) -> None:
+        """Publish an event to all subscribers."""
+        with self._lock:
+            callbacks = list(self._subscribers.get(event_type, []))
+        for callback in callbacks:
+            try:
+                callback(event)
+            except Exception:
+                pass
+
+    def clear(self) -> None:
+        """Remove all subscribers."""
+        with self._lock:
+            self._subscribers.clear()
+
+    def subscriber_count(self, event_type: EventType | None = None) -> int:
+        """Get subscriber count for an event type, or total if None."""
+        with self._lock:
+            if event_type is None:
+                return sum(len(cb) for cb in self._subscribers.values())
+            return len(self._subscribers.get(event_type, []))
+
+
+_event_bus: EventBus | None = None
+
+
+def get_event_bus() -> EventBus:
+    """Get the global event bus instance."""
+    global _event_bus
+    if _event_bus is None:
+        _event_bus = EventBus()
+    return _event_bus
+
+
+def set_event_bus(bus: EventBus) -> None:
+    """Set the global event bus instance (for testing)."""
+    global _event_bus
+    _event_bus = bus

engine/events.py

@@ -0,0 +1,67 @@
+"""
+Event types for the mainline application.
+Defines the core events that flow through the system.
+These types support a future migration to an event-driven architecture.
+"""
+
+from dataclasses import dataclass
+from datetime import datetime
+from enum import Enum, auto
+
+
+class EventType(Enum):
+    """Core event types in the mainline application."""
+
+    NEW_HEADLINE = auto()
+    FRAME_TICK = auto()
+    MIC_LEVEL = auto()
+    NTFY_MESSAGE = auto()
+    STREAM_START = auto()
+    STREAM_END = auto()
+
+
+@dataclass
+class HeadlineEvent:
+    """Event emitted when a new headline is ready for display."""
+
+    title: str
+    source: str
+    timestamp: str
+    language: str | None = None
+
+
+@dataclass
+class FrameTickEvent:
+    """Event emitted on each render frame."""
+
+    frame_number: int
+    timestamp: datetime
+    delta_seconds: float
+
+
+@dataclass
+class MicLevelEvent:
+    """Event emitted when microphone level changes significantly."""
+
+    db_level: float
+    excess_above_threshold: float
+    timestamp: datetime
+
+
+@dataclass
+class NtfyMessageEvent:
+    """Event emitted when an ntfy message is received."""
+
+    title: str
+    body: str
+    message_id: str | None = None
+    timestamp: datetime | None = None
+
+
+@dataclass
+class StreamEvent:
+    """Event emitted when stream starts or ends."""
+
+    event_type: EventType
+    headline_count: int = 0
+    timestamp: datetime | None = None

engine/fetch.py

@@ -8,6 +8,7 @@ import pathlib
 import re
 import urllib.request
 from datetime import datetime
+from typing import Any
 
 import feedparser
 
@@ -16,9 +17,13 @@ from engine.filter import skip, strip_tags
 from engine.sources import FEEDS, POETRY_SOURCES
 from engine.terminal import boot_ln
 
+# Type alias for headline items
+HeadlineTuple = tuple[str, str, str]
+
 
 # ─── SINGLE FEED ──────────────────────────────────────────
-def fetch_feed(url):
+def fetch_feed(url: str) -> Any | None:
+    """Fetch and parse a single RSS feed URL."""
     try:
         req = urllib.request.Request(url, headers={"User-Agent": "mainline/0.1"})
         resp = urllib.request.urlopen(req, timeout=config.FEED_TIMEOUT)
@@ -28,8 +33,9 @@ def fetch_feed(url):
 
 
 # ─── ALL RSS FEEDS ────────────────────────────────────────
-def fetch_all():
-    items = []
+def fetch_all() -> tuple[list[HeadlineTuple], int, int]:
+    """Fetch all RSS feeds and return items, linked count, failed count."""
+    items: list[HeadlineTuple] = []
     linked = failed = 0
     for src, url in FEEDS.items():
         feed = fetch_feed(url)
@@ -59,7 +65,7 @@ def fetch_all():
 
 
 # ─── PROJECT GUTENBERG ────────────────────────────────────
-def _fetch_gutenberg(url, label):
+def _fetch_gutenberg(url: str, label: str) -> list[HeadlineTuple]:
     """Download and parse stanzas/passages from a Project Gutenberg text."""
     try:
         req = urllib.request.Request(url, headers={"User-Agent": "mainline/0.1"})

engine/frame.py

@@ -0,0 +1,57 @@
+"""
+Frame timing utilities — FPS control and precise timing.
+"""
+
+import time
+
+
+class FrameTimer:
+    """Frame timer for consistent render loop timing."""
+
+    def __init__(self, target_frame_dt: float = 0.05):
+        self.target_frame_dt = target_frame_dt
+        self._frame_count = 0
+        self._start_time = time.monotonic()
+        self._last_frame_time = self._start_time
+
+    @property
+    def fps(self) -> float:
+        """Current FPS based on elapsed frames."""
+        elapsed = time.monotonic() - self._start_time
+        if elapsed > 0:
+            return self._frame_count / elapsed
+        return 0.0
+
+    def sleep_until_next_frame(self) -> float:
+        """Sleep to maintain target frame rate. Returns actual elapsed time."""
+        now = time.monotonic()
+        elapsed = now - self._last_frame_time
+        self._last_frame_time = now
+        self._frame_count += 1
+
+        sleep_time = max(0, self.target_frame_dt - elapsed)
+        if sleep_time > 0:
+            time.sleep(sleep_time)
+        return elapsed
+
+    def reset(self) -> None:
+        """Reset frame counter and start time."""
+        self._frame_count = 0
+        self._start_time = time.monotonic()
+        self._last_frame_time = self._start_time
+
+
+def calculate_scroll_step(
+    scroll_dur: float, view_height: int, padding: int = 15
+) -> float:
+    """Calculate scroll step interval for smooth scrolling.
+
+    Args:
+        scroll_dur: Duration in seconds for one headline to scroll through view
+        view_height: Terminal height in rows
+        padding: Extra rows for off-screen content
+
+    Returns:
+        Time in seconds between scroll steps
+    """
+    return scroll_dur / (view_height + padding) * 2

engine/layers.py

@@ -0,0 +1,260 @@
+"""
+Layer compositing — message overlay, ticker zone, firehose, noise.
+Depends on: config, render, effects.
+"""
+
+import random
+import re
+import time
+from datetime import datetime
+
+from engine import config
+from engine.effects import (
+    EffectChain,
+    EffectContext,
+    fade_line,
+    firehose_line,
+    glitch_bar,
+    noise,
+    vis_trunc,
+)
+from engine.render import big_wrap, lr_gradient, msg_gradient
+from engine.terminal import RST, W_COOL
+
+MSG_META = "\033[38;5;245m"
+MSG_BORDER = "\033[2;38;5;37m"
+
+
+def render_message_overlay(
+    msg: tuple[str, str, float] | None,
+    w: int,
+    h: int,
+    msg_cache: tuple,
+) -> tuple[list[str], tuple]:
+    """Render ntfy message overlay.
+
+    Args:
+        msg: (title, body, timestamp) or None
+        w: terminal width
+        h: terminal height
+        msg_cache: (cache_key, rendered_rows) for caching
+
+    Returns:
+        (list of ANSI strings, updated cache)
+    """
+    overlay = []
+    if msg is None:
+        return overlay, msg_cache
+
+    m_title, m_body, m_ts = msg
+    display_text = m_body or m_title or "(empty)"
+    display_text = re.sub(r"\s+", " ", display_text.upper())
+
+    cache_key = (display_text, w)
+    if msg_cache[0] != cache_key:
+        msg_rows = big_wrap(display_text, w - 4)
+        msg_cache = (cache_key, msg_rows)
+    else:
+        msg_rows = msg_cache[1]
+
+    msg_rows = msg_gradient(
+        msg_rows, (time.monotonic() * config.GRAD_SPEED) % 1.0
+    )
+
+    elapsed_s = int(time.monotonic() - m_ts)
+    remaining = max(0, config.MESSAGE_DISPLAY_SECS - elapsed_s)
+    ts_str = datetime.now().strftime("%H:%M:%S")
+    panel_h = len(msg_rows) + 2
+    panel_top = max(0, (h - panel_h) // 2)
+
+    row_idx = 0
+    for mr in msg_rows:
+        ln = vis_trunc(mr, w)
+        overlay.append(f"\033[{panel_top + row_idx + 1};1H  {ln}\033[0m\033[K")
+        row_idx += 1
+
+    meta_parts = []
+    if m_title and m_title != m_body:
+        meta_parts.append(m_title)
+    meta_parts.append(f"ntfy \u00b7 {ts_str} \u00b7 {remaining}s")
+    meta = (
+        "  " + " \u00b7 ".join(meta_parts)
+        if len(meta_parts) > 1
+        else "  " + meta_parts[0]
+    )
+    overlay.append(f"\033[{panel_top + row_idx + 1};1H{MSG_META}{meta}\033[0m\033[K")
+    row_idx += 1
+
+    bar = "\u2500" * (w - 4)
+    overlay.append(f"\033[{panel_top + row_idx + 1};1H  {MSG_BORDER}{bar}\033[0m\033[K")
+
+    return overlay, msg_cache
+
+
+def render_ticker_zone(
+    active: list,
+    scroll_cam: int,
+    ticker_h: int,
+    w: int,
+    noise_cache: dict,
+    grad_offset: float,
+) -> tuple[list[str], dict]:
+    """Render the ticker scroll zone.
+
+    Args:
+        active: list of (content_rows, color, canvas_y, meta_idx)
+        scroll_cam: camera position (viewport top)
+        ticker_h: height of ticker zone
+        w: terminal width
+        noise_cache: dict of cy -> noise string
+        grad_offset: gradient animation offset
+
+    Returns:
+        (list of ANSI strings, updated noise_cache)
+    """
+    buf = []
+    top_zone = max(1, int(ticker_h * 0.25))
+    bot_zone = max(1, int(ticker_h * 0.10))
+
+    def noise_at(cy):
+        if cy not in noise_cache:
+            noise_cache[cy] = noise(w) if random.random() < 0.15 else None
+        return noise_cache[cy]
+
+    for r in range(ticker_h):
+        scr_row = r + 1
+        cy = scroll_cam + r
+        top_f = min(1.0, r / top_zone) if top_zone > 0 else 1.0
+        bot_f = min(1.0, (ticker_h - 1 - r) / bot_zone) if bot_zone > 0 else 1.0
+        row_fade = min(top_f, bot_f)
+        drawn = False
+
+        for content, hc, by, midx in active:
+            cr = cy - by
+            if 0 <= cr < len(content):
+                raw = content[cr]
+                if cr != midx:
+                    colored = lr_gradient([raw], grad_offset)[0]
+                else:
+                    colored = raw
+                ln = vis_trunc(colored, w)
+                if row_fade < 1.0:
+                    ln = fade_line(ln, row_fade)
+
+                if cr == midx:
+                    buf.append(f"\033[{scr_row};1H{W_COOL}{ln}{RST}\033[K")
+                elif ln.strip():
+                    buf.append(f"\033[{scr_row};1H{ln}{RST}\033[K")
+                else:
+                    buf.append(f"\033[{scr_row};1H\033[K")
+                drawn = True
+                break
+
+        if not drawn:
+            n = noise_at(cy)
+            if row_fade < 1.0 and n:
+                n = fade_line(n, row_fade)
+            if n:
+                buf.append(f"\033[{scr_row};1H{n}")
+            else:
+                buf.append(f"\033[{scr_row};1H\033[K")
+
+    return buf, noise_cache
+
+
+def apply_glitch(
+    buf: list[str],
+    ticker_buf_start: int,
+    mic_excess: float,
+    w: int,
+) -> list[str]:
+    """Apply glitch effect to ticker buffer.
+
+    Args:
+        buf: current buffer
+        ticker_buf_start: index where ticker starts in buffer
+        mic_excess: mic level above threshold
+        w: terminal width
+
+    Returns:
+        Updated buffer with glitches applied
+    """
+    glitch_prob = 0.32 + min(0.9, mic_excess * 0.16)
+    n_hits = 4 + int(mic_excess / 2)
+    ticker_buf_len = len(buf) - ticker_buf_start
+
+    if random.random() < glitch_prob and ticker_buf_len > 0:
+        for _ in range(min(n_hits, ticker_buf_len)):
+            gi = random.randint(0, ticker_buf_len - 1)
+            scr_row = gi + 1
+            buf[ticker_buf_start + gi] = f"\033[{scr_row};1H{glitch_bar(w)}"
+
+    return buf
+
+
+def render_firehose(items: list, w: int, fh: int, h: int) -> list[str]:
+    """Render firehose strip at bottom of screen."""
+    buf = []
+    if fh > 0:
+        for fr in range(fh):
+            scr_row = h - fh + fr + 1
+            fline = firehose_line(items, w)
+            buf.append(f"\033[{scr_row};1H{fline}\033[K")
+    return buf
+
+
+_effect_chain = None
+
+
+def init_effects() -> None:
+    """Initialize effect plugins and chain."""
+    global _effect_chain
+    from engine.effects import EffectChain, get_registry
+
+    registry = get_registry()
+
+    import effects_plugins
+
+    effects_plugins.discover_plugins()
+
+    chain = EffectChain(registry)
+    chain.set_order(["noise", "fade", "glitch", "firehose"])
+    _effect_chain = chain
+
+
+def process_effects(
+    buf: list[str],
+    w: int,
+    h: int,
+    scroll_cam: int,
+    ticker_h: int,
+    mic_excess: float,
+    grad_offset: float,
+    frame_number: int,
+    has_message: bool,
+    items: list,
+) -> list[str]:
+    """Process buffer through effect chain."""
+    if _effect_chain is None:
+        init_effects()
+
+    ctx = EffectContext(
+        terminal_width=w,
+        terminal_height=h,
+        scroll_cam=scroll_cam,
+        ticker_height=ticker_h,
+        mic_excess=mic_excess,
+        grad_offset=grad_offset,
+        frame_number=frame_number,
+        has_message=has_message,
+        items=items,
+    )
+    return _effect_chain.process(buf, ctx)
+
+
+def get_effect_chain() -> EffectChain | None:
+    """Get the effect chain instance."""
+    global _effect_chain
+    if _effect_chain is None:
+        init_effects()
+    return _effect_chain

engine/mic.py

@@ -4,6 +4,8 @@ Gracefully degrades if sounddevice/numpy are unavailable.
 """
 
 import atexit
+from collections.abc import Callable
+from datetime import datetime
 
 try:
     import numpy as _np
@@ -14,6 +16,9 @@ except Exception:
     _HAS_MIC = False
 
 
+from engine.events import MicLevelEvent
+
+
 class MicMonitor:
     """Background mic stream that exposes current RMS dB level."""
 
@@ -21,6 +26,7 @@ class MicMonitor:
         self.threshold_db = threshold_db
         self._db = -99.0
         self._stream = None
+        self._subscribers: list[Callable[[MicLevelEvent], None]] = []
 
     @property
     def available(self):
@@ -37,6 +43,23 @@ class MicMonitor:
         """dB above threshold (clamped to 0)."""
         return max(0.0, self._db - self.threshold_db)
 
+    def subscribe(self, callback: Callable[[MicLevelEvent], None]) -> None:
+        """Register a callback to be called when mic level changes."""
+        self._subscribers.append(callback)
+
+    def unsubscribe(self, callback: Callable[[MicLevelEvent], None]) -> None:
+        """Remove a registered callback."""
+        if callback in self._subscribers:
+            self._subscribers.remove(callback)
+
+    def _emit(self, event: MicLevelEvent) -> None:
+        """Emit an event to all subscribers."""
+        for cb in self._subscribers:
+            try:
+                cb(event)
+            except Exception:
+                pass
+
     def start(self):
         """Start background mic stream. Returns True on success, False/None otherwise."""
         if not _HAS_MIC:
@@ -45,6 +68,13 @@ class MicMonitor:
         def _cb(indata, frames, t, status):
             rms = float(_np.sqrt(_np.mean(indata**2)))
             self._db = 20 * _np.log10(rms) if rms > 0 else -99.0
+            if self._subscribers:
+                event = MicLevelEvent(
+                    db_level=self._db,
+                    excess_above_threshold=max(0.0, self._db - self.threshold_db),
+                    timestamp=datetime.now(),
+                )
+                self._emit(event)
 
         try:
             self._stream = _sd.InputStream(

engine/ntfy.py

@@ -16,8 +16,12 @@ import json
 import threading
 import time
 import urllib.request
+from collections.abc import Callable
+from datetime import datetime
 from urllib.parse import parse_qs, urlencode, urlparse, urlunparse
 
+from engine.events import NtfyMessageEvent
+
 
 class NtfyPoller:
     """SSE stream listener for ntfy.sh topics. Messages arrive in ~1s (network RTT)."""
@@ -28,6 +32,24 @@ class NtfyPoller:
         self.display_secs = display_secs
         self._message = None  # (title, body, monotonic_timestamp) or None
         self._lock = threading.Lock()
+        self._subscribers: list[Callable[[NtfyMessageEvent], None]] = []
+
+    def subscribe(self, callback: Callable[[NtfyMessageEvent], None]) -> None:
+        """Register a callback to be called when a message is received."""
+        self._subscribers.append(callback)
+
+    def unsubscribe(self, callback: Callable[[NtfyMessageEvent], None]) -> None:
+        """Remove a registered callback."""
+        if callback in self._subscribers:
+            self._subscribers.remove(callback)
+
+    def _emit(self, event: NtfyMessageEvent) -> None:
+        """Emit an event to all subscribers."""
+        for cb in self._subscribers:
+            try:
+                cb(event)
+            except Exception:
+                pass
 
     def start(self):
         """Start background stream thread. Returns True."""
@@ -88,6 +110,13 @@ class NtfyPoller:
                                 data.get("message", ""),
                                 time.monotonic(),
                             )
+                        event = NtfyMessageEvent(
+                            title=data.get("title", ""),
+                            body=data.get("message", ""),
+                            message_id=data.get("id"),
+                            timestamp=datetime.now(),
+                        )
+                        self._emit(event)
             except Exception:
                 pass
             time.sleep(self.reconnect_delay)

engine/scroll.py

@@ -1,148 +1,92 @@
 """
 Render engine — ticker content, scroll motion, message panel, and firehose overlay.
-Depends on: config, terminal, render, effects, ntfy, mic.
+Orchestrates viewport, frame timing, and layers.
 """
 
 import random
-import re
-import sys
 import time
-from datetime import datetime
 
 from engine import config
-from engine.effects import (
-    fade_line,
-    firehose_line,
-    glitch_bar,
-    next_headline,
-    noise,
-    vis_trunc,
+from engine.display import (
+    Display,
+    TerminalDisplay,
 )
-from engine.render import big_wrap, lr_gradient, make_block, msg_gradient
-from engine.terminal import CLR, RST, W_COOL, th, tw
+from engine.display import (
+    get_monitor as _get_display_monitor,
+)
+from engine.frame import calculate_scroll_step
+from engine.layers import (
+    apply_glitch,
+    process_effects,
+    render_firehose,
+    render_message_overlay,
+    render_ticker_zone,
+)
+from engine.viewport import th, tw
+
+USE_EFFECT_CHAIN = True
 
 
-def stream(items, ntfy_poller, mic_monitor):
+def stream(items, ntfy_poller, mic_monitor, display: Display | None = None):
     """Main render loop with four layers: message, ticker, scroll motion, firehose."""
+    if display is None:
+        display = TerminalDisplay()
     random.shuffle(items)
     pool = list(items)
     seen = set()
     queued = 0
 
     time.sleep(0.5)
-    sys.stdout.write(CLR)
-    sys.stdout.flush()
-
     w, h = tw(), th()
+    display.init(w, h)
+    display.clear()
     fh = config.FIREHOSE_H if config.FIREHOSE else 0
-    ticker_view_h = h - fh  # reserve fixed firehose strip at bottom
-    GAP = 3  # blank rows between headlines
-    scroll_step_interval = config.SCROLL_DUR / (ticker_view_h + 15) * 2
+    ticker_view_h = h - fh
+    GAP = 3
+    scroll_step_interval = calculate_scroll_step(config.SCROLL_DUR, ticker_view_h)
 
-    # Taxonomy:
-    # - message: centered ntfy overlay panel
-    # - ticker: large headline text content
-    # - scroll: upward camera motion applied to ticker content
-    # - firehose: fixed carriage-return style strip pinned at bottom
-    # Active ticker blocks: (content_rows, color, canvas_y, meta_idx)
     active = []
-    scroll_cam = 0  # viewport top in virtual canvas coords
-    ticker_next_y = (
-        ticker_view_h  # canvas-y where next block starts (off-screen bottom)
-    )
+    scroll_cam = 0
+    ticker_next_y = ticker_view_h
     noise_cache = {}
     scroll_motion_accum = 0.0
+    msg_cache = (None, None)
+    frame_number = 0
 
-    def _noise_at(cy):
-        if cy not in noise_cache:
-            noise_cache[cy] = noise(w) if random.random() < 0.15 else None
-        return noise_cache[cy]
+    while True:
+        if queued >= config.HEADLINE_LIMIT and not active:
+            break
 
-    # Message color: bright cyan/white — distinct from headline greens
-    MSG_META = "\033[38;5;245m"  # cool grey
-    MSG_BORDER = "\033[2;38;5;37m"  # dim teal
-    _msg_cache = (None, None)  # (cache_key, rendered_rows)
-
-    while queued < config.HEADLINE_LIMIT or active:
         t0 = time.monotonic()
         w, h = tw(), th()
         fh = config.FIREHOSE_H if config.FIREHOSE else 0
         ticker_view_h = h - fh
+        scroll_step_interval = calculate_scroll_step(config.SCROLL_DUR, ticker_view_h)
 
-        # ── Check for ntfy message ────────────────────────
-        msg_h = 0
-        msg_overlay = []
         msg = ntfy_poller.get_active_message()
+        msg_overlay, msg_cache = render_message_overlay(msg, w, h, msg_cache)
 
         buf = []
-        if msg is not None:
-            m_title, m_body, m_ts = msg
-            # ── Message overlay: centered in the viewport ──
-            display_text = m_body or m_title or "(empty)"
-            display_text = re.sub(r"\s+", " ", display_text.upper())
-            cache_key = (display_text, w)
-            if _msg_cache[0] != cache_key:
-                msg_rows = big_wrap(display_text, w - 4)
-                _msg_cache = (cache_key, msg_rows)
-            else:
-                msg_rows = _msg_cache[1]
-            msg_rows = msg_gradient(
-                msg_rows, (time.monotonic() * config.GRAD_SPEED) % 1.0
-            )
-            # Layout: rendered text + meta + border
-            elapsed_s = int(time.monotonic() - m_ts)
-            remaining = max(0, config.MESSAGE_DISPLAY_SECS - elapsed_s)
-            ts_str = datetime.now().strftime("%H:%M:%S")
-            panel_h = len(msg_rows) + 2  # meta + border
-            panel_top = max(0, (h - panel_h) // 2)
-            row_idx = 0
-            for mr in msg_rows:
-                ln = vis_trunc(mr, w)
-                msg_overlay.append(
-                    f"\033[{panel_top + row_idx + 1};1H  {ln}{RST}\033[K"
-                )
-                row_idx += 1
-            # Meta line: title (if distinct) + source + countdown
-            meta_parts = []
-            if m_title and m_title != m_body:
-                meta_parts.append(m_title)
-            meta_parts.append(f"ntfy \u00b7 {ts_str} \u00b7 {remaining}s")
-            meta = (
-                "  " + " \u00b7 ".join(meta_parts)
-                if len(meta_parts) > 1
-                else "  " + meta_parts[0]
-            )
-            msg_overlay.append(
-                f"\033[{panel_top + row_idx + 1};1H{MSG_META}{meta}{RST}\033[K"
-            )
-            row_idx += 1
-            # Border — constant boundary under message panel
-            bar = "\u2500" * (w - 4)
-            msg_overlay.append(
-                f"\033[{panel_top + row_idx + 1};1H  {MSG_BORDER}{bar}{RST}\033[K"
-            )
+        ticker_h = ticker_view_h
 
-        # Ticker draws above the fixed firehose strip; message is a centered overlay.
-        ticker_h = ticker_view_h - msg_h
-
-        # ── Ticker content + scroll motion (always runs) ──
         scroll_motion_accum += config.FRAME_DT
         while scroll_motion_accum >= scroll_step_interval:
             scroll_motion_accum -= scroll_step_interval
             scroll_cam += 1
 
-            # Enqueue new headlines when room at the bottom
             while (
                 ticker_next_y < scroll_cam + ticker_view_h + 10
                 and queued < config.HEADLINE_LIMIT
             ):
+                from engine.effects import next_headline
+                from engine.render import make_block
+
                 t, src, ts = next_headline(pool, items, seen)
                 ticker_content, hc, midx = make_block(t, src, ts, w)
                 active.append((ticker_content, hc, ticker_next_y, midx))
                 ticker_next_y += len(ticker_content) + GAP
                 queued += 1
 
-            # Prune off-screen blocks and stale noise
             active = [
                 (c, hc, by, mi) for c, hc, by, mi in active if by + len(c) > scroll_cam
             ]
@@ -150,71 +94,48 @@ def stream(items, ntfy_poller, mic_monitor):
                 if k < scroll_cam:
                     del noise_cache[k]
 
-        # Draw ticker zone (above fixed firehose strip)
-        top_zone = max(1, int(ticker_h * 0.25))
-        bot_zone = max(1, int(ticker_h * 0.10))
         grad_offset = (time.monotonic() * config.GRAD_SPEED) % 1.0
-        ticker_buf_start = len(buf)  # track where ticker rows start in buf
-        for r in range(ticker_h):
-            scr_row = r + 1  # 1-indexed ANSI screen row
-            cy = scroll_cam + r
-            top_f = min(1.0, r / top_zone) if top_zone > 0 else 1.0
-            bot_f = min(1.0, (ticker_h - 1 - r) / bot_zone) if bot_zone > 0 else 1.0
-            row_fade = min(top_f, bot_f)
-            drawn = False
-            for content, hc, by, midx in active:
-                cr = cy - by
-                if 0 <= cr < len(content):
-                    raw = content[cr]
-                    if cr != midx:
-                        colored = lr_gradient([raw], grad_offset)[0]
-                    else:
-                        colored = raw
-                    ln = vis_trunc(colored, w)
-                    if row_fade < 1.0:
-                        ln = fade_line(ln, row_fade)
-                    if cr == midx:
-                        buf.append(f"\033[{scr_row};1H{W_COOL}{ln}{RST}\033[K")
-                    elif ln.strip():
-                        buf.append(f"\033[{scr_row};1H{ln}{RST}\033[K")
-                    else:
-                        buf.append(f"\033[{scr_row};1H\033[K")
-                    drawn = True
-                    break
-            if not drawn:
-                n = _noise_at(cy)
-                if row_fade < 1.0 and n:
-                    n = fade_line(n, row_fade)
-                if n:
-                    buf.append(f"\033[{scr_row};1H{n}")
-                else:
-                    buf.append(f"\033[{scr_row};1H\033[K")
+        ticker_buf_start = len(buf)
+
+        ticker_buf, noise_cache = render_ticker_zone(
+            active, scroll_cam, ticker_h, w, noise_cache, grad_offset
+        )
+        buf.extend(ticker_buf)
 
-        # Glitch — base rate + mic-reactive spikes (ticker zone only)
         mic_excess = mic_monitor.excess
-        glitch_prob = 0.32 + min(0.9, mic_excess * 0.16)
-        n_hits = 4 + int(mic_excess / 2)
-        ticker_buf_len = len(buf) - ticker_buf_start
-        if random.random() < glitch_prob and ticker_buf_len > 0:
-            for _ in range(min(n_hits, ticker_buf_len)):
-                gi = random.randint(0, ticker_buf_len - 1)
-                scr_row = gi + 1
-                buf[ticker_buf_start + gi] = f"\033[{scr_row};1H{glitch_bar(w)}"
+        render_start = time.perf_counter()
+
+        if USE_EFFECT_CHAIN:
+            buf = process_effects(
+                buf,
+                w,
+                h,
+                scroll_cam,
+                ticker_h,
+                mic_excess,
+                grad_offset,
+                frame_number,
+                msg is not None,
+                items,
+            )
+        else:
+            buf = apply_glitch(buf, ticker_buf_start, mic_excess, w)
+            firehose_buf = render_firehose(items, w, fh, h)
+            buf.extend(firehose_buf)
 
-        if config.FIREHOSE and fh > 0:
-            for fr in range(fh):
-                scr_row = h - fh + fr + 1
-                fline = firehose_line(items, w)
-                buf.append(f"\033[{scr_row};1H{fline}\033[K")
         if msg_overlay:
             buf.extend(msg_overlay)
 
-        sys.stdout.buffer.write("".join(buf).encode())
-        sys.stdout.flush()
+        render_elapsed = (time.perf_counter() - render_start) * 1000
+        monitor = _get_display_monitor()
+        if monitor:
+            chars = sum(len(line) for line in buf)
+            monitor.record_effect("render", render_elapsed, chars, chars)
+
+        display.show(buf)
 
-        # Precise frame timing
         elapsed = time.monotonic() - t0
         time.sleep(max(0, config.FRAME_DT - elapsed))
+        frame_number += 1
 
-    sys.stdout.write(CLR)
-    sys.stdout.flush()
+    display.cleanup()

engine/translate.py

@@ -7,26 +7,16 @@ import json
 import re
 import urllib.parse
 import urllib.request
+from functools import lru_cache
 
 from engine.sources import LOCATION_LANGS
 
-_TRANSLATE_CACHE = {}
+TRANSLATE_CACHE_SIZE = 500
 
 
-def detect_location_language(title):
-    """Detect if headline mentions a location, return target language."""
-    title_lower = title.lower()
-    for pattern, lang in LOCATION_LANGS.items():
-        if re.search(pattern, title_lower):
-            return lang
-    return None
-
-
-def translate_headline(title, target_lang):
-    """Translate headline via Google Translate API (zero dependencies)."""
-    key = (title, target_lang)
-    if key in _TRANSLATE_CACHE:
-        return _TRANSLATE_CACHE[key]
+@lru_cache(maxsize=TRANSLATE_CACHE_SIZE)
+def _translate_cached(title: str, target_lang: str) -> str:
+    """Cached translation implementation."""
     try:
         q = urllib.parse.quote(title)
         url = (
@@ -39,5 +29,18 @@ def translate_headline(title, target_lang):
         result = "".join(p[0] for p in data[0] if p[0]) or title
     except Exception:
         result = title
-    _TRANSLATE_CACHE[key] = result
     return result
+
+
+def detect_location_language(title):
+    """Detect if headline mentions a location, return target language."""
+    title_lower = title.lower()
+    for pattern, lang in LOCATION_LANGS.items():
+        if re.search(pattern, title_lower):
+            return lang
+    return None
+
+
+def translate_headline(title: str, target_lang: str) -> str:
+    """Translate headline via Google Translate API (zero dependencies)."""
+    return _translate_cached(title, target_lang)

engine/types.py

@@ -0,0 +1,60 @@
+"""
+Shared dataclasses for the mainline application.
+Provides named types for tuple returns across modules.
+"""
+
+from dataclasses import dataclass
+
+
+@dataclass
+class HeadlineItem:
+    """A single headline item: title, source, and timestamp."""
+
+    title: str
+    source: str
+    timestamp: str
+
+    def to_tuple(self) -> tuple[str, str, str]:
+        """Convert to tuple for backward compatibility."""
+        return (self.title, self.source, self.timestamp)
+
+    @classmethod
+    def from_tuple(cls, t: tuple[str, str, str]) -> "HeadlineItem":
+        """Create from tuple for backward compatibility."""
+        return cls(title=t[0], source=t[1], timestamp=t[2])
+
+
+def items_to_tuples(items: list[HeadlineItem]) -> list[tuple[str, str, str]]:
+    """Convert list of HeadlineItem to list of tuples."""
+    return [item.to_tuple() for item in items]
+
+
+def tuples_to_items(tuples: list[tuple[str, str, str]]) -> list[HeadlineItem]:
+    """Convert list of tuples to list of HeadlineItem."""
+    return [HeadlineItem.from_tuple(t) for t in tuples]
+
+
+@dataclass
+class FetchResult:
+    """Result from fetch_all() or fetch_poetry()."""
+
+    items: list[HeadlineItem]
+    linked: int
+    failed: int
+
+    def to_legacy_tuple(self) -> tuple[list[tuple], int, int]:
+        """Convert to legacy tuple format for backward compatibility."""
+        return ([item.to_tuple() for item in self.items], self.linked, self.failed)
+
+
+@dataclass
+class Block:
+    """Rendered headline block from make_block()."""
+
+    content: list[str]
+    color: str
+    meta_row_index: int
+
+    def to_legacy_tuple(self) -> tuple[list[str], str, int]:
+        """Convert to legacy tuple format for backward compatibility."""
+        return (self.content, self.color, self.meta_row_index)

engine/viewport.py

@@ -0,0 +1,37 @@
+"""
+Viewport utilities — terminal dimensions and ANSI positioning helpers.
+No internal dependencies.
+"""
+
+import os
+
+
+def tw() -> int:
+    """Get terminal width (columns)."""
+    try:
+        return os.get_terminal_size().columns
+    except Exception:
+        return 80
+
+
+def th() -> int:
+    """Get terminal height (lines)."""
+    try:
+        return os.get_terminal_size().lines
+    except Exception:
+        return 24
+
+
+def move_to(row: int, col: int = 1) -> str:
+    """Generate ANSI escape to move cursor to row, col (1-indexed)."""
+    return f"\033[{row};{col}H"
+
+
+def clear_screen() -> str:
+    """Clear screen and move cursor to home."""
+    return "\033[2J\033[H"
+
+
+def clear_line() -> str:
+    """Clear current line."""
+    return "\033[K"

pyproject.toml

@@ -22,6 +22,7 @@ classifiers = [
 dependencies = [
     "feedparser>=6.0.0",
     "Pillow>=10.0.0",
+    "pyright>=1.1.408",
 ]
 
 [project.optional-dependencies]

tests/fixtures/__init__.py

@@ -0,0 +1,236 @@
+"""
+Pytest fixtures for mocking external dependencies (network, filesystem).
+"""
+
+import json
+from unittest.mock import MagicMock
+
+import pytest
+
+
+@pytest.fixture
+def mock_feed_response():
+    """Mock RSS feed response data."""
+    return b"""<?xml version="1.0" encoding="UTF-8" ?>
+<rss version="2.0">
+  <channel>
+    <title>Test Feed</title>
+    <link>https://example.com</link>
+    <item>
+      <title>Test Headline One</title>
+      <pubDate>Sat, 15 Mar 2025 12:00:00 GMT</pubDate>
+    </item>
+    <item>
+      <title>Test Headline Two</title>
+      <pubDate>Sat, 15 Mar 2025 11:00:00 GMT</pubDate>
+    </item>
+    <item>
+      <title>Sports: Team Wins Championship</title>
+      <pubDate>Sat, 15 Mar 2025 10:00:00 GMT</pubDate>
+    </item>
+  </channel>
+</rss>"""
+
+
+@pytest.fixture
+def mock_gutenberg_response():
+    """Mock Project Gutenberg text response."""
+    return """Project Gutenberg's Collection, by Various
+
+*** START OF SOME TEXT ***
+This is a test poem with multiple lines
+that should be parsed as stanzas.
+
+Another stanza here with different content
+and more lines to test the parsing logic.
+
+Yet another stanza for variety
+in the test data.
+
+*** END OF SOME TEXT ***"""
+
+
+@pytest.fixture
+def mock_gutenberg_empty():
+    """Mock Gutenberg response with no valid stanzas."""
+    return """Project Gutenberg's Collection
+
+*** START OF TEXT ***
+THIS IS ALL CAPS AND SHOULD BE SKIPPED
+
+I.
+
+*** END OF TEXT ***"""
+
+
+@pytest.fixture
+def mock_ntfy_message():
+    """Mock ntfy.sh SSE message."""
+    return json.dumps(
+        {
+            "id": "test123",
+            "event": "message",
+            "title": "Test Title",
+            "message": "Test message body",
+            "time": 1234567890,
+        }
+    ).encode()
+
+
+@pytest.fixture
+def mock_ntfy_keepalive():
+    """Mock ntfy.sh keepalive message."""
+    return b'data: {"event":"keepalive"}\n\n'
+
+
+@pytest.fixture
+def mock_google_translate_response():
+    """Mock Google Translate API response."""
+    return json.dumps(
+        [
+            [["Translated text", "Original text", None, 0.8], None, "en"],
+            None,
+            None,
+            [],
+            [],
+            [],
+            [],
+        ]
+    )
+
+
+@pytest.fixture
+def mock_feedparser():
+    """Create a mock feedparser.parse function."""
+
+    def _mock(data):
+        mock_result = MagicMock()
+        mock_result.bozo = False
+        mock_result.entries = [
+            {
+                "title": "Test Headline",
+                "published_parsed": (2025, 3, 15, 12, 0, 0, 0, 0, 0),
+            },
+            {
+                "title": "Another Headline",
+                "updated_parsed": (2025, 3, 15, 11, 0, 0, 0, 0, 0),
+            },
+        ]
+        return mock_result
+
+    return _mock
+
+
+@pytest.fixture
+def mock_urllib_open(mock_feed_response):
+    """Create a mock urllib.request.urlopen that returns feed data."""
+
+    def _mock(url):
+        mock_response = MagicMock()
+        mock_response.read.return_value = mock_feed_response
+        return mock_response
+
+    return _mock
+
+
+@pytest.fixture
+def sample_items():
+    """Sample items as returned by fetch module (title, source, timestamp)."""
+    return [
+        ("Headline One", "Test Source", "12:00"),
+        ("Headline Two", "Another Source", "11:30"),
+        ("Headline Three", "Third Source", "10:45"),
+    ]
+
+
+@pytest.fixture
+def sample_config():
+    """Sample config for testing."""
+    from engine.config import Config
+
+    return Config(
+        headline_limit=100,
+        feed_timeout=10,
+        mic_threshold_db=50,
+        mode="news",
+        firehose=False,
+        ntfy_topic="https://ntfy.sh/test/json",
+        ntfy_reconnect_delay=5,
+        message_display_secs=30,
+        font_dir="fonts",
+        font_path="",
+        font_index=0,
+        font_picker=False,
+        font_sz=60,
+        render_h=8,
+        ssaa=4,
+        scroll_dur=5.625,
+        frame_dt=0.05,
+        firehose_h=12,
+        grad_speed=0.08,
+        glitch_glyphs="░▒▓█▌▐",
+        kata_glyphs="ﾊﾐﾋｰｳ",
+        script_fonts={},
+    )
+
+
+@pytest.fixture
+def poetry_config():
+    """Sample config for poetry mode."""
+    from engine.config import Config
+
+    return Config(
+        headline_limit=100,
+        feed_timeout=10,
+        mic_threshold_db=50,
+        mode="poetry",
+        firehose=False,
+        ntfy_topic="https://ntfy.sh/test/json",
+        ntfy_reconnect_delay=5,
+        message_display_secs=30,
+        font_dir="fonts",
+        font_path="",
+        font_index=0,
+        font_picker=False,
+        font_sz=60,
+        render_h=8,
+        ssaa=4,
+        scroll_dur=5.625,
+        frame_dt=0.05,
+        firehose_h=12,
+        grad_speed=0.08,
+        glitch_glyphs="░▒▓█▌▐",
+        kata_glyphs="ﾊﾐﾋｰｳ",
+        script_fonts={},
+    )
+
+
+@pytest.fixture
+def firehose_config():
+    """Sample config with firehose enabled."""
+    from engine.config import Config
+
+    return Config(
+        headline_limit=100,
+        feed_timeout=10,
+        mic_threshold_db=50,
+        mode="news",
+        firehose=True,
+        ntfy_topic="https://ntfy.sh/test/json",
+        ntfy_reconnect_delay=5,
+        message_display_secs=30,
+        font_dir="fonts",
+        font_path="",
+        font_index=0,
+        font_picker=False,
+        font_sz=60,
+        render_h=8,
+        ssaa=4,
+        scroll_dur=5.625,
+        frame_dt=0.05,
+        firehose_h=12,
+        grad_speed=0.08,
+        glitch_glyphs="░▒▓█▌▐",
+        kata_glyphs="ﾊﾐﾋｰｳ",
+        script_fonts={},
+    )

tests/test_config.py

@@ -164,53 +164,138 @@ class TestSetFontSelection:
         assert original_index == config.FONT_INDEX
 
 
-class TestActiveTheme:
-    """Tests for ACTIVE_THEME global and set_active_theme function."""
+class TestConfigDataclass:
+    """Tests for Config dataclass."""
 
-    def test_active_theme_initially_none(self):
-        """ACTIVE_THEME should be None at module start."""
-        # Reset to None to test initial state
-        original = config.ACTIVE_THEME
-        config.ACTIVE_THEME = None
-        try:
-            assert config.ACTIVE_THEME is None
-        finally:
-            config.ACTIVE_THEME = original
+    def test_config_has_required_fields(self):
+        """Config has all required fields."""
+        c = config.Config()
+        assert hasattr(c, "headline_limit")
+        assert hasattr(c, "feed_timeout")
+        assert hasattr(c, "mic_threshold_db")
+        assert hasattr(c, "mode")
+        assert hasattr(c, "firehose")
+        assert hasattr(c, "ntfy_topic")
+        assert hasattr(c, "ntfy_reconnect_delay")
+        assert hasattr(c, "message_display_secs")
+        assert hasattr(c, "font_dir")
+        assert hasattr(c, "font_path")
+        assert hasattr(c, "font_index")
+        assert hasattr(c, "font_picker")
+        assert hasattr(c, "font_sz")
+        assert hasattr(c, "render_h")
+        assert hasattr(c, "ssaa")
+        assert hasattr(c, "scroll_dur")
+        assert hasattr(c, "frame_dt")
+        assert hasattr(c, "firehose_h")
+        assert hasattr(c, "grad_speed")
+        assert hasattr(c, "glitch_glyphs")
+        assert hasattr(c, "kata_glyphs")
+        assert hasattr(c, "script_fonts")
 
-    def test_set_active_theme_green(self):
-        """Setting green theme works correctly."""
-        config.set_active_theme("green")
-        assert config.ACTIVE_THEME is not None
-        assert config.ACTIVE_THEME.name == "green"
-        assert len(config.ACTIVE_THEME.main_gradient) == 12
-        assert len(config.ACTIVE_THEME.message_gradient) == 12
+    def test_config_defaults(self):
+        """Config has sensible defaults."""
+        c = config.Config()
+        assert c.headline_limit == 1000
+        assert c.feed_timeout == 10
+        assert c.mic_threshold_db == 50
+        assert c.mode == "news"
+        assert c.firehose is False
+        assert c.ntfy_reconnect_delay == 5
+        assert c.message_display_secs == 30
 
-    def test_set_active_theme_default(self):
-        """Default theme is green when not specified."""
-        config.set_active_theme()
-        assert config.ACTIVE_THEME is not None
-        assert config.ACTIVE_THEME.name == "green"
+    def test_config_is_immutable(self):
+        """Config is frozen (immutable)."""
+        c = config.Config()
+        with pytest.raises(AttributeError):
+            c.headline_limit = 500  # type: ignore
 
-    def test_set_active_theme_invalid(self):
-        """Invalid theme_id raises KeyError."""
-        with pytest.raises(KeyError):
-            config.set_active_theme("nonexistent")
+    def test_config_custom_values(self):
+        """Config accepts custom values."""
+        c = config.Config(
+            headline_limit=500,
+            mode="poetry",
+            firehose=True,
+            ntfy_topic="https://ntfy.sh/test",
+        )
+        assert c.headline_limit == 500
+        assert c.mode == "poetry"
+        assert c.firehose is True
+        assert c.ntfy_topic == "https://ntfy.sh/test"
 
-    def test_set_active_theme_all_themes(self):
-        """Verify orange and purple themes work."""
-        # Test orange
-        config.set_active_theme("orange")
-        assert config.ACTIVE_THEME.name == "orange"
 
-        # Test purple
-        config.set_active_theme("purple")
-        assert config.ACTIVE_THEME.name == "purple"
+class TestConfigFromArgs:
+    """Tests for Config.from_args method."""
 
-    def test_set_active_theme_idempotent(self):
-        """Calling set_active_theme multiple times works."""
-        config.set_active_theme("green")
-        first_theme = config.ACTIVE_THEME
-        config.set_active_theme("green")
-        second_theme = config.ACTIVE_THEME
-        assert first_theme.name == second_theme.name
-        assert first_theme.name == "green"
+    def test_from_args_defaults(self):
+        """from_args creates config with defaults from empty argv."""
+        c = config.Config.from_args(["prog"])
+        assert c.mode == "news"
+        assert c.firehose is False
+        assert c.font_picker is True
+
+    def test_from_args_poetry_mode(self):
+        """from_args detects --poetry flag."""
+        c = config.Config.from_args(["prog", "--poetry"])
+        assert c.mode == "poetry"
+
+    def test_from_args_poetry_short_flag(self):
+        """from_args detects -p short flag."""
+        c = config.Config.from_args(["prog", "-p"])
+        assert c.mode == "poetry"
+
+    def test_from_args_firehose(self):
+        """from_args detects --firehose flag."""
+        c = config.Config.from_args(["prog", "--firehose"])
+        assert c.firehose is True
+
+    def test_from_args_no_font_picker(self):
+        """from_args detects --no-font-picker flag."""
+        c = config.Config.from_args(["prog", "--no-font-picker"])
+        assert c.font_picker is False
+
+    def test_from_args_font_index(self):
+        """from_args parses --font-index."""
+        c = config.Config.from_args(["prog", "--font-index", "3"])
+        assert c.font_index == 3
+
+
+class TestGetSetConfig:
+    """Tests for get_config and set_config functions."""
+
+    def test_get_config_returns_config(self):
+        """get_config returns a Config instance."""
+        c = config.get_config()
+        assert isinstance(c, config.Config)
+
+    def test_set_config_allows_injection(self):
+        """set_config allows injecting a custom config."""
+        custom = config.Config(mode="poetry", headline_limit=100)
+        config.set_config(custom)
+        assert config.get_config().mode == "poetry"
+        assert config.get_config().headline_limit == 100
+
+    def test_set_config_then_get_config(self):
+        """set_config followed by get_config returns the set config."""
+        original = config.get_config()
+        test_config = config.Config(headline_limit=42)
+        config.set_config(test_config)
+        result = config.get_config()
+        assert result.headline_limit == 42
+        config.set_config(original)
+
+
+class TestPlatformFontPaths:
+    """Tests for platform font path detection."""
+
+    def test_get_platform_font_paths_returns_dict(self):
+        """_get_platform_font_paths returns a dictionary."""
+        fonts = config._get_platform_font_paths()
+        assert isinstance(fonts, dict)
+
+    def test_platform_font_paths_common_languages(self):
+        """Common language font mappings exist."""
+        fonts = config._get_platform_font_paths()
+        common = {"ja", "zh-cn", "ko", "ru", "ar", "hi"}
+        found = set(fonts.keys()) & common
+        assert len(found) > 0

tests/test_controller.py

@@ -0,0 +1,117 @@
+"""
+Tests for engine.controller module.
+"""
+
+from unittest.mock import MagicMock, patch
+
+from engine import config
+from engine.controller import StreamController
+
+
+class TestStreamController:
+    """Tests for StreamController class."""
+
+    def test_init_default_config(self):
+        """StreamController initializes with default config."""
+        controller = StreamController()
+        assert controller.config is not None
+        assert isinstance(controller.config, config.Config)
+
+    def test_init_custom_config(self):
+        """StreamController accepts custom config."""
+        custom_config = config.Config(headline_limit=500)
+        controller = StreamController(config=custom_config)
+        assert controller.config.headline_limit == 500
+
+    def test_init_sources_none_by_default(self):
+        """Sources are None until initialized."""
+        controller = StreamController()
+        assert controller.mic is None
+        assert controller.ntfy is None
+
+    @patch("engine.controller.MicMonitor")
+    @patch("engine.controller.NtfyPoller")
+    def test_initialize_sources(self, mock_ntfy, mock_mic):
+        """initialize_sources creates mic and ntfy instances."""
+        mock_mic_instance = MagicMock()
+        mock_mic_instance.available = True
+        mock_mic_instance.start.return_value = True
+        mock_mic.return_value = mock_mic_instance
+
+        mock_ntfy_instance = MagicMock()
+        mock_ntfy_instance.start.return_value = True
+        mock_ntfy.return_value = mock_ntfy_instance
+
+        controller = StreamController()
+        mic_ok, ntfy_ok = controller.initialize_sources()
+
+        assert mic_ok is True
+        assert ntfy_ok is True
+        assert controller.mic is not None
+        assert controller.ntfy is not None
+
+    @patch("engine.controller.MicMonitor")
+    @patch("engine.controller.NtfyPoller")
+    def test_initialize_sources_mic_unavailable(self, mock_ntfy, mock_mic):
+        """initialize_sources handles unavailable mic."""
+        mock_mic_instance = MagicMock()
+        mock_mic_instance.available = False
+        mock_mic.return_value = mock_mic_instance
+
+        mock_ntfy_instance = MagicMock()
+        mock_ntfy_instance.start.return_value = True
+        mock_ntfy.return_value = mock_ntfy_instance
+
+        controller = StreamController()
+        mic_ok, ntfy_ok = controller.initialize_sources()
+
+        assert mic_ok is False
+        assert ntfy_ok is True
+
+
+class TestStreamControllerCleanup:
+    """Tests for StreamController cleanup."""
+
+    @patch("engine.controller.MicMonitor")
+    def test_cleanup_stops_mic(self, mock_mic):
+        """cleanup stops the microphone if running."""
+        mock_mic_instance = MagicMock()
+        mock_mic.return_value = mock_mic_instance
+
+        controller = StreamController()
+        controller.mic = mock_mic_instance
+        controller.cleanup()
+
+        mock_mic_instance.stop.assert_called_once()
+
+
+class TestStreamControllerWarmup:
+    """Tests for StreamController topic warmup."""
+
+    def test_warmup_topics_idempotent(self):
+        """warmup_topics can be called multiple times."""
+        StreamController._topics_warmed = False
+
+        with patch("urllib.request.urlopen") as mock_urlopen:
+            StreamController.warmup_topics()
+            StreamController.warmup_topics()
+
+            assert mock_urlopen.call_count >= 3
+
+    def test_warmup_topics_sets_flag(self):
+        """warmup_topics sets the warmed flag."""
+        StreamController._topics_warmed = False
+
+        with patch("urllib.request.urlopen"):
+            StreamController.warmup_topics()
+
+            assert StreamController._topics_warmed is True
+
+    def test_warmup_topics_skips_after_first(self):
+        """warmup_topics skips after first call."""
+        StreamController._topics_warmed = True
+
+        with patch("urllib.request.urlopen") as mock_urlopen:
+            StreamController.warmup_topics()
+
+            mock_urlopen.assert_not_called()

tests/test_display.py

@@ -0,0 +1,79 @@
+"""
+Tests for engine.display module.
+"""
+
+from engine.display import NullDisplay, TerminalDisplay
+
+
+class TestDisplayProtocol:
+    """Test that display backends satisfy the Display protocol."""
+
+    def test_terminal_display_is_display(self):
+        """TerminalDisplay satisfies Display protocol."""
+        display = TerminalDisplay()
+        assert hasattr(display, "init")
+        assert hasattr(display, "show")
+        assert hasattr(display, "clear")
+        assert hasattr(display, "cleanup")
+
+    def test_null_display_is_display(self):
+        """NullDisplay satisfies Display protocol."""
+        display = NullDisplay()
+        assert hasattr(display, "init")
+        assert hasattr(display, "show")
+        assert hasattr(display, "clear")
+        assert hasattr(display, "cleanup")
+
+
+class TestTerminalDisplay:
+    """Tests for TerminalDisplay class."""
+
+    def test_init_sets_dimensions(self):
+        """init stores terminal dimensions."""
+        display = TerminalDisplay()
+        display.init(80, 24)
+        assert display.width == 80
+        assert display.height == 24
+
+    def test_show_returns_none(self):
+        """show returns None after writing to stdout."""
+        display = TerminalDisplay()
+        display.width = 80
+        display.height = 24
+        display.show(["line1", "line2"])
+
+    def test_clear_does_not_error(self):
+        """clear works without error."""
+        display = TerminalDisplay()
+        display.clear()
+
+    def test_cleanup_does_not_error(self):
+        """cleanup works without error."""
+        display = TerminalDisplay()
+        display.cleanup()
+
+
+class TestNullDisplay:
+    """Tests for NullDisplay class."""
+
+    def test_init_stores_dimensions(self):
+        """init stores dimensions."""
+        display = NullDisplay()
+        display.init(100, 50)
+        assert display.width == 100
+        assert display.height == 50
+
+    def test_show_does_nothing(self):
+        """show discards buffer without error."""
+        display = NullDisplay()
+        display.show(["line1", "line2", "line3"])
+
+    def test_clear_does_nothing(self):
+        """clear does nothing."""
+        display = NullDisplay()
+        display.clear()
+
+    def test_cleanup_does_nothing(self):
+        """cleanup does nothing."""
+        display = NullDisplay()
+        display.cleanup()

tests/test_effects.py

@@ -0,0 +1,427 @@
+"""
+Tests for engine.effects module.
+"""
+
+from engine.effects import EffectChain, EffectConfig, EffectContext, EffectRegistry
+
+
+class MockEffect:
+    name = "mock"
+    config = EffectConfig(enabled=True, intensity=1.0)
+
+    def __init__(self):
+        self.processed = False
+        self.last_ctx = None
+
+    def process(self, buf, ctx):
+        self.processed = True
+        self.last_ctx = ctx
+        return buf + ["processed"]
+
+    def configure(self, config):
+        self.config = config
+
+
+class TestEffectConfig:
+    def test_defaults(self):
+        cfg = EffectConfig()
+        assert cfg.enabled is True
+        assert cfg.intensity == 1.0
+        assert cfg.params == {}
+
+    def test_custom_values(self):
+        cfg = EffectConfig(enabled=False, intensity=0.5, params={"key": "value"})
+        assert cfg.enabled is False
+        assert cfg.intensity == 0.5
+        assert cfg.params == {"key": "value"}
+
+
+class TestEffectContext:
+    def test_defaults(self):
+        ctx = EffectContext(
+            terminal_width=80,
+            terminal_height=24,
+            scroll_cam=0,
+            ticker_height=20,
+            mic_excess=0.0,
+            grad_offset=0.0,
+            frame_number=0,
+            has_message=False,
+        )
+        assert ctx.terminal_width == 80
+        assert ctx.terminal_height == 24
+        assert ctx.ticker_height == 20
+        assert ctx.items == []
+
+    def test_with_items(self):
+        items = [("Title", "Source", "12:00")]
+        ctx = EffectContext(
+            terminal_width=80,
+            terminal_height=24,
+            scroll_cam=0,
+            ticker_height=20,
+            mic_excess=0.0,
+            grad_offset=0.0,
+            frame_number=0,
+            has_message=False,
+            items=items,
+        )
+        assert ctx.items == items
+
+
+class TestEffectRegistry:
+    def test_init_empty(self):
+        registry = EffectRegistry()
+        assert len(registry.list_all()) == 0
+
+    def test_register(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        registry.register(effect)
+        assert "mock" in registry.list_all()
+
+    def test_get(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        registry.register(effect)
+        retrieved = registry.get("mock")
+        assert retrieved is effect
+
+    def test_get_nonexistent(self):
+        registry = EffectRegistry()
+        assert registry.get("nonexistent") is None
+
+    def test_enable(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.config.enabled = False
+        registry.register(effect)
+        registry.enable("mock")
+        assert effect.config.enabled is True
+
+    def test_disable(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.config.enabled = True
+        registry.register(effect)
+        registry.disable("mock")
+        assert effect.config.enabled is False
+
+    def test_list_enabled(self):
+        registry = EffectRegistry()
+
+        class EnabledEffect:
+            name = "enabled_effect"
+            config = EffectConfig(enabled=True, intensity=1.0)
+
+        class DisabledEffect:
+            name = "disabled_effect"
+            config = EffectConfig(enabled=False, intensity=1.0)
+
+        registry.register(EnabledEffect())
+        registry.register(DisabledEffect())
+        enabled = registry.list_enabled()
+        assert len(enabled) == 1
+        assert enabled[0].name == "enabled_effect"
+
+    def test_configure(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        registry.register(effect)
+        new_config = EffectConfig(enabled=False, intensity=0.3)
+        registry.configure("mock", new_config)
+        assert effect.config.enabled is False
+        assert effect.config.intensity == 0.3
+
+    def test_is_enabled(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.config.enabled = True
+        registry.register(effect)
+        assert registry.is_enabled("mock") is True
+        assert registry.is_enabled("nonexistent") is False
+
+
+class TestEffectChain:
+    def test_init(self):
+        registry = EffectRegistry()
+        chain = EffectChain(registry)
+        assert chain.get_order() == []
+
+    def test_set_order(self):
+        registry = EffectRegistry()
+        effect1 = MockEffect()
+        effect1.name = "effect1"
+        effect2 = MockEffect()
+        effect2.name = "effect2"
+        registry.register(effect1)
+        registry.register(effect2)
+        chain = EffectChain(registry)
+        chain.set_order(["effect1", "effect2"])
+        assert chain.get_order() == ["effect1", "effect2"]
+
+    def test_add_effect(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.name = "test_effect"
+        registry.register(effect)
+        chain = EffectChain(registry)
+        chain.add_effect("test_effect")
+        assert "test_effect" in chain.get_order()
+
+    def test_add_effect_invalid(self):
+        registry = EffectRegistry()
+        chain = EffectChain(registry)
+        result = chain.add_effect("nonexistent")
+        assert result is False
+
+    def test_remove_effect(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.name = "test_effect"
+        registry.register(effect)
+        chain = EffectChain(registry)
+        chain.set_order(["test_effect"])
+        chain.remove_effect("test_effect")
+        assert "test_effect" not in chain.get_order()
+
+    def test_reorder(self):
+        registry = EffectRegistry()
+        effect1 = MockEffect()
+        effect1.name = "effect1"
+        effect2 = MockEffect()
+        effect2.name = "effect2"
+        effect3 = MockEffect()
+        effect3.name = "effect3"
+        registry.register(effect1)
+        registry.register(effect2)
+        registry.register(effect3)
+        chain = EffectChain(registry)
+        chain.set_order(["effect1", "effect2", "effect3"])
+        result = chain.reorder(["effect3", "effect1", "effect2"])
+        assert result is True
+        assert chain.get_order() == ["effect3", "effect1", "effect2"]
+
+    def test_reorder_invalid(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.name = "effect1"
+        registry.register(effect)
+        chain = EffectChain(registry)
+        result = chain.reorder(["effect1", "nonexistent"])
+        assert result is False
+
+    def test_process_empty_chain(self):
+        registry = EffectRegistry()
+        chain = EffectChain(registry)
+        buf = ["line1", "line2"]
+        ctx = EffectContext(
+            terminal_width=80,
+            terminal_height=24,
+            scroll_cam=0,
+            ticker_height=20,
+            mic_excess=0.0,
+            grad_offset=0.0,
+            frame_number=0,
+            has_message=False,
+        )
+        result = chain.process(buf, ctx)
+        assert result == buf
+
+    def test_process_with_effects(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.name = "test_effect"
+        registry.register(effect)
+        chain = EffectChain(registry)
+        chain.set_order(["test_effect"])
+        buf = ["line1", "line2"]
+        ctx = EffectContext(
+            terminal_width=80,
+            terminal_height=24,
+            scroll_cam=0,
+            ticker_height=20,
+            mic_excess=0.0,
+            grad_offset=0.0,
+            frame_number=0,
+            has_message=False,
+        )
+        result = chain.process(buf, ctx)
+        assert result == ["line1", "line2", "processed"]
+        assert effect.processed is True
+        assert effect.last_ctx is ctx
+
+    def test_process_disabled_effect(self):
+        registry = EffectRegistry()
+        effect = MockEffect()
+        effect.name = "test_effect"
+        effect.config.enabled = False
+        registry.register(effect)
+        chain = EffectChain(registry)
+        chain.set_order(["test_effect"])
+        buf = ["line1"]
+        ctx = EffectContext(
+            terminal_width=80,
+            terminal_height=24,
+            scroll_cam=0,
+            ticker_height=20,
+            mic_excess=0.0,
+            grad_offset=0.0,
+            frame_number=0,
+            has_message=False,
+        )
+        result = chain.process(buf, ctx)
+        assert result == ["line1"]
+        assert effect.processed is False
+
+
+class TestEffectsExports:
+    def test_all_exports_are_importable(self):
+        """Verify all exports in __all__ can actually be imported."""
+        import engine.effects as effects_module
+
+        for name in effects_module.__all__:
+            getattr(effects_module, name)
+
+
+class TestPerformanceMonitor:
+    def test_empty_stats(self):
+        from engine.effects.performance import PerformanceMonitor
+
+        monitor = PerformanceMonitor()
+        stats = monitor.get_stats()
+        assert "error" in stats
+
+    def test_record_and_retrieve(self):
+        from engine.effects.performance import PerformanceMonitor
+
+        monitor = PerformanceMonitor()
+        monitor.start_frame(1)
+        monitor.record_effect("test_effect", 1.5, 100, 150)
+        monitor.end_frame(1, 2.0)
+
+        stats = monitor.get_stats()
+        assert "error" not in stats
+        assert stats["frame_count"] == 1
+        assert "test_effect" in stats["effects"]
+
+    def test_multiple_frames(self):
+        from engine.effects.performance import PerformanceMonitor
+
+        monitor = PerformanceMonitor(max_frames=3)
+        for i in range(5):
+            monitor.start_frame(i)
+            monitor.record_effect("effect1", 1.0, 100, 100)
+            monitor.record_effect("effect2", 0.5, 100, 100)
+            monitor.end_frame(i, 1.5)
+
+        stats = monitor.get_stats()
+        assert stats["frame_count"] == 3
+        assert "effect1" in stats["effects"]
+        assert "effect2" in stats["effects"]
+
+    def test_reset(self):
+        from engine.effects.performance import PerformanceMonitor
+
+        monitor = PerformanceMonitor()
+        monitor.start_frame(1)
+        monitor.record_effect("test", 1.0, 100, 100)
+        monitor.end_frame(1, 1.0)
+
+        monitor.reset()
+        stats = monitor.get_stats()
+        assert "error" in stats
+
+
+class TestEffectPipelinePerformance:
+    def test_pipeline_stays_within_frame_budget(self):
+        """Verify effect pipeline completes within frame budget (33ms for 30fps)."""
+        from engine.effects import (
+            EffectChain,
+            EffectConfig,
+            EffectContext,
+            EffectRegistry,
+        )
+
+        class DummyEffect:
+            name = "dummy"
+            config = EffectConfig(enabled=True, intensity=1.0)
+
+            def process(self, buf, ctx):
+                return [line * 2 for line in buf]
+
+        registry = EffectRegistry()
+        registry.register(DummyEffect())
+
+        from engine.effects.performance import PerformanceMonitor
+
+        monitor = PerformanceMonitor(max_frames=10)
+        chain = EffectChain(registry, monitor)
+        chain.set_order(["dummy"])
+
+        buf = ["x" * 80] * 20
+
+        for i in range(10):
+            ctx = EffectContext(
+                terminal_width=80,
+                terminal_height=24,
+                scroll_cam=0,
+                ticker_height=20,
+                mic_excess=0.0,
+                grad_offset=0.0,
+                frame_number=i,
+                has_message=False,
+            )
+            chain.process(buf, ctx)
+
+        stats = monitor.get_stats()
+        assert "error" not in stats
+        assert stats["pipeline"]["max_ms"] < 33.0
+
+    def test_individual_effects_performance(self):
+        """Verify individual effects don't exceed 10ms per frame."""
+        from engine.effects import (
+            EffectChain,
+            EffectConfig,
+            EffectContext,
+            EffectRegistry,
+        )
+
+        class SlowEffect:
+            name = "slow"
+            config = EffectConfig(enabled=True, intensity=1.0)
+
+            def process(self, buf, ctx):
+                result = []
+                for line in buf:
+                    result.append(line)
+                    result.append(line + line)
+                return result
+
+        registry = EffectRegistry()
+        registry.register(SlowEffect())
+
+        from engine.effects.performance import PerformanceMonitor
+
+        monitor = PerformanceMonitor(max_frames=5)
+        chain = EffectChain(registry, monitor)
+        chain.set_order(["slow"])
+
+        buf = ["x" * 80] * 10
+
+        for i in range(5):
+            ctx = EffectContext(
+                terminal_width=80,
+                terminal_height=24,
+                scroll_cam=0,
+                ticker_height=20,
+                mic_excess=0.0,
+                grad_offset=0.0,
+                frame_number=i,
+                has_message=False,
+            )
+            chain.process(buf, ctx)
+
+        stats = monitor.get_stats()
+        assert "error" not in stats
+        assert stats["effects"]["slow"]["max_ms"] < 10.0

tests/test_effects_controller.py

@@ -0,0 +1,117 @@
+"""
+Tests for engine.effects.controller module.
+"""
+
+from unittest.mock import MagicMock, patch
+
+from engine.effects.controller import (
+    handle_effects_command,
+    set_effect_chain_ref,
+)
+
+
+class TestHandleEffectsCommand:
+    """Tests for handle_effects_command function."""
+
+    def test_list_effects(self):
+        """list command returns formatted effects list."""
+        with patch("engine.effects.controller.get_registry") as mock_registry:
+            mock_plugin = MagicMock()
+            mock_plugin.config.enabled = True
+            mock_plugin.config.intensity = 0.5
+            mock_registry.return_value.list_all.return_value = {"noise": mock_plugin}
+
+            with patch("engine.effects.controller._get_effect_chain") as mock_chain:
+                mock_chain.return_value.get_order.return_value = ["noise"]
+
+                result = handle_effects_command("/effects list")
+
+                assert "noise: ON" in result
+                assert "intensity=0.5" in result
+
+    def test_enable_effect(self):
+        """enable command calls registry.enable."""
+        with patch("engine.effects.controller.get_registry") as mock_registry:
+            mock_plugin = MagicMock()
+            mock_registry.return_value.get.return_value = mock_plugin
+            mock_registry.return_value.list_all.return_value = {"noise": mock_plugin}
+
+            result = handle_effects_command("/effects noise on")
+
+            assert "Enabled: noise" in result
+            mock_registry.return_value.enable.assert_called_once_with("noise")
+
+    def test_disable_effect(self):
+        """disable command calls registry.disable."""
+        with patch("engine.effects.controller.get_registry") as mock_registry:
+            mock_plugin = MagicMock()
+            mock_registry.return_value.get.return_value = mock_plugin
+            mock_registry.return_value.list_all.return_value = {"noise": mock_plugin}
+
+            result = handle_effects_command("/effects noise off")
+
+            assert "Disabled: noise" in result
+            mock_registry.return_value.disable.assert_called_once_with("noise")
+
+    def test_set_intensity(self):
+        """intensity command sets plugin intensity."""
+        with patch("engine.effects.controller.get_registry") as mock_registry:
+            mock_plugin = MagicMock()
+            mock_plugin.config.intensity = 0.5
+            mock_registry.return_value.get.return_value = mock_plugin
+            mock_registry.return_value.list_all.return_value = {"noise": mock_plugin}
+
+            result = handle_effects_command("/effects noise intensity 0.8")
+
+            assert "intensity to 0.8" in result
+            assert mock_plugin.config.intensity == 0.8
+
+    def test_invalid_intensity_range(self):
+        """intensity outside 0.0-1.0 returns error."""
+        with patch("engine.effects.controller.get_registry") as mock_registry:
+            mock_plugin = MagicMock()
+            mock_registry.return_value.get.return_value = mock_plugin
+            mock_registry.return_value.list_all.return_value = {"noise": mock_plugin}
+
+            result = handle_effects_command("/effects noise intensity 1.5")
+
+            assert "between 0.0 and 1.0" in result
+
+    def test_reorder_pipeline(self):
+        """reorder command calls chain.reorder."""
+        with patch("engine.effects.controller.get_registry") as mock_registry:
+            mock_registry.return_value.list_all.return_value = {}
+
+            with patch("engine.effects.controller._get_effect_chain") as mock_chain:
+                mock_chain_instance = MagicMock()
+                mock_chain_instance.reorder.return_value = True
+                mock_chain.return_value = mock_chain_instance
+
+                result = handle_effects_command("/effects reorder noise,fade")
+
+                assert "Reordered pipeline" in result
+                mock_chain_instance.reorder.assert_called_once_with(["noise", "fade"])
+
+    def test_unknown_command(self):
+        """unknown command returns error."""
+        result = handle_effects_command("/unknown")
+        assert "Unknown command" in result
+
+    def test_non_effects_command(self):
+        """non-effects command returns error."""
+        result = handle_effects_command("not a command")
+        assert "Unknown command" in result
+
+
+class TestSetEffectChainRef:
+    """Tests for set_effect_chain_ref function."""
+
+    def test_sets_global_ref(self):
+        """set_effect_chain_ref updates global reference."""
+        mock_chain = MagicMock()
+        set_effect_chain_ref(mock_chain)
+
+        from engine.effects.controller import _get_effect_chain
+
+        result = _get_effect_chain()
+        assert result == mock_chain

tests/test_emitters.py

@@ -0,0 +1,69 @@
+"""
+Tests for engine.emitters module.
+"""
+
+from engine.emitters import EventEmitter, Startable, Stoppable
+
+
+class TestEventEmitterProtocol:
+    """Tests for EventEmitter protocol."""
+
+    def test_protocol_exists(self):
+        """EventEmitter protocol is defined."""
+        assert EventEmitter is not None
+
+    def test_protocol_has_subscribe_method(self):
+        """EventEmitter has subscribe method in protocol."""
+        assert hasattr(EventEmitter, "subscribe")
+
+    def test_protocol_has_unsubscribe_method(self):
+        """EventEmitter has unsubscribe method in protocol."""
+        assert hasattr(EventEmitter, "unsubscribe")
+
+
+class TestStartableProtocol:
+    """Tests for Startable protocol."""
+
+    def test_protocol_exists(self):
+        """Startable protocol is defined."""
+        assert Startable is not None
+
+    def test_protocol_has_start_method(self):
+        """Startable has start method in protocol."""
+        assert hasattr(Startable, "start")
+
+
+class TestStoppableProtocol:
+    """Tests for Stoppable protocol."""
+
+    def test_protocol_exists(self):
+        """Stoppable protocol is defined."""
+        assert Stoppable is not None
+
+    def test_protocol_has_stop_method(self):
+        """Stoppable has stop method in protocol."""
+        assert hasattr(Stoppable, "stop")
+
+
+class TestProtocolCompliance:
+    """Tests that existing classes comply with protocols."""
+
+    def test_ntfy_poller_complies_with_protocol(self):
+        """NtfyPoller implements EventEmitter protocol."""
+        from engine.ntfy import NtfyPoller
+
+        poller = NtfyPoller("http://example.com/topic")
+        assert hasattr(poller, "subscribe")
+        assert hasattr(poller, "unsubscribe")
+        assert callable(poller.subscribe)
+        assert callable(poller.unsubscribe)
+
+    def test_mic_monitor_complies_with_protocol(self):
+        """MicMonitor implements EventEmitter and Startable protocols."""
+        from engine.mic import MicMonitor
+
+        monitor = MicMonitor()
+        assert hasattr(monitor, "subscribe")
+        assert hasattr(monitor, "unsubscribe")
+        assert hasattr(monitor, "start")
+        assert hasattr(monitor, "stop")

tests/test_eventbus.py

@@ -0,0 +1,202 @@
+"""
+Tests for engine.eventbus module.
+"""
+
+
+from engine.eventbus import EventBus, get_event_bus, set_event_bus
+from engine.events import EventType, NtfyMessageEvent
+
+
+class TestEventBusInit:
+    """Tests for EventBus initialization."""
+
+    def test_init_creates_empty_subscribers(self):
+        """EventBus starts with no subscribers."""
+        bus = EventBus()
+        assert bus.subscriber_count() == 0
+
+
+class TestEventBusSubscribe:
+    """Tests for EventBus.subscribe method."""
+
+    def test_subscribe_adds_callback(self):
+        """subscribe() adds a callback for an event type."""
+        bus = EventBus()
+        def callback(e):
+            return None
+
+        bus.subscribe(EventType.NTFY_MESSAGE, callback)
+
+        assert bus.subscriber_count(EventType.NTFY_MESSAGE) == 1
+
+    def test_subscribe_multiple_callbacks_same_event(self):
+        """Multiple callbacks can be subscribed to the same event type."""
+        bus = EventBus()
+        def cb1(e):
+            return None
+        def cb2(e):
+            return None
+
+        bus.subscribe(EventType.NTFY_MESSAGE, cb1)
+        bus.subscribe(EventType.NTFY_MESSAGE, cb2)
+
+        assert bus.subscriber_count(EventType.NTFY_MESSAGE) == 2
+
+    def test_subscribe_different_event_types(self):
+        """Callbacks can be subscribed to different event types."""
+        bus = EventBus()
+        def cb1(e):
+            return None
+        def cb2(e):
+            return None
+
+        bus.subscribe(EventType.NTFY_MESSAGE, cb1)
+        bus.subscribe(EventType.MIC_LEVEL, cb2)
+
+        assert bus.subscriber_count(EventType.NTFY_MESSAGE) == 1
+        assert bus.subscriber_count(EventType.MIC_LEVEL) == 1
+
+
+class TestEventBusUnsubscribe:
+    """Tests for EventBus.unsubscribe method."""
+
+    def test_unsubscribe_removes_callback(self):
+        """unsubscribe() removes a callback."""
+        bus = EventBus()
+        def callback(e):
+            return None
+
+        bus.subscribe(EventType.NTFY_MESSAGE, callback)
+        bus.unsubscribe(EventType.NTFY_MESSAGE, callback)
+
+        assert bus.subscriber_count(EventType.NTFY_MESSAGE) == 0
+
+    def test_unsubscribe_nonexistent_callback_no_error(self):
+        """unsubscribe() handles non-existent callback gracefully."""
+        bus = EventBus()
+        def callback(e):
+            return None
+
+        bus.unsubscribe(EventType.NTFY_MESSAGE, callback)
+
+
+class TestEventBusPublish:
+    """Tests for EventBus.publish method."""
+
+    def test_publish_calls_subscriber(self):
+        """publish() calls the subscriber callback."""
+        bus = EventBus()
+        received = []
+
+        def callback(event):
+            received.append(event)
+
+        bus.subscribe(EventType.NTFY_MESSAGE, callback)
+        event = NtfyMessageEvent(title="Test", body="Body")
+        bus.publish(EventType.NTFY_MESSAGE, event)
+
+        assert len(received) == 1
+        assert received[0].title == "Test"
+
+    def test_publish_multiple_subscribers(self):
+        """publish() calls all subscribers for an event type."""
+        bus = EventBus()
+        received1 = []
+        received2 = []
+
+        def callback1(event):
+            received1.append(event)
+
+        def callback2(event):
+            received2.append(event)
+
+        bus.subscribe(EventType.NTFY_MESSAGE, callback1)
+        bus.subscribe(EventType.NTFY_MESSAGE, callback2)
+        event = NtfyMessageEvent(title="Test", body="Body")
+        bus.publish(EventType.NTFY_MESSAGE, event)
+
+        assert len(received1) == 1
+        assert len(received2) == 1
+
+    def test_publish_different_event_types(self):
+        """publish() only calls subscribers for the specific event type."""
+        bus = EventBus()
+        ntfy_received = []
+        mic_received = []
+
+        def ntfy_callback(event):
+            ntfy_received.append(event)
+
+        def mic_callback(event):
+            mic_received.append(event)
+
+        bus.subscribe(EventType.NTFY_MESSAGE, ntfy_callback)
+        bus.subscribe(EventType.MIC_LEVEL, mic_callback)
+        event = NtfyMessageEvent(title="Test", body="Body")
+        bus.publish(EventType.NTFY_MESSAGE, event)
+
+        assert len(ntfy_received) == 1
+        assert len(mic_received) == 0
+
+
+class TestEventBusClear:
+    """Tests for EventBus.clear method."""
+
+    def test_clear_removes_all_subscribers(self):
+        """clear() removes all subscribers."""
+        bus = EventBus()
+        def cb1(e):
+            return None
+        def cb2(e):
+            return None
+
+        bus.subscribe(EventType.NTFY_MESSAGE, cb1)
+        bus.subscribe(EventType.MIC_LEVEL, cb2)
+        bus.clear()
+
+        assert bus.subscriber_count() == 0
+
+
+class TestEventBusThreadSafety:
+    """Tests for EventBus thread safety."""
+
+    def test_concurrent_subscribe_unsubscribe(self):
+        """subscribe and unsubscribe can be called concurrently."""
+        import threading
+
+        bus = EventBus()
+        callbacks = [lambda e: None for _ in range(10)]
+
+        def subscribe():
+            for cb in callbacks:
+                bus.subscribe(EventType.NTFY_MESSAGE, cb)
+
+        def unsubscribe():
+            for cb in callbacks:
+                bus.unsubscribe(EventType.NTFY_MESSAGE, cb)
+
+        t1 = threading.Thread(target=subscribe)
+        t2 = threading.Thread(target=unsubscribe)
+        t1.start()
+        t2.start()
+        t1.join()
+        t2.join()
+
+
+class TestGlobalEventBus:
+    """Tests for global event bus functions."""
+
+    def test_get_event_bus_returns_singleton(self):
+        """get_event_bus() returns the same instance."""
+        bus1 = get_event_bus()
+        bus2 = get_event_bus()
+        assert bus1 is bus2
+
+    def test_set_event_bus_replaces_singleton(self):
+        """set_event_bus() replaces the global event bus."""
+        new_bus = EventBus()
+        set_event_bus(new_bus)
+        try:
+            assert get_event_bus() is new_bus
+        finally:
+            set_event_bus(None)

tests/test_events.py

@@ -0,0 +1,112 @@
+"""
+Tests for engine.events module.
+"""
+
+from datetime import datetime
+
+from engine import events
+
+
+class TestEventType:
+    """Tests for EventType enum."""
+
+    def test_event_types_exist(self):
+        """All expected event types exist."""
+        assert hasattr(events.EventType, "NEW_HEADLINE")
+        assert hasattr(events.EventType, "FRAME_TICK")
+        assert hasattr(events.EventType, "MIC_LEVEL")
+        assert hasattr(events.EventType, "NTFY_MESSAGE")
+        assert hasattr(events.EventType, "STREAM_START")
+        assert hasattr(events.EventType, "STREAM_END")
+
+
+class TestHeadlineEvent:
+    """Tests for HeadlineEvent dataclass."""
+
+    def test_create_headline_event(self):
+        """HeadlineEvent can be created with required fields."""
+        e = events.HeadlineEvent(
+            title="Test Headline",
+            source="Test Source",
+            timestamp="12:00",
+        )
+        assert e.title == "Test Headline"
+        assert e.source == "Test Source"
+        assert e.timestamp == "12:00"
+
+    def test_headline_event_optional_language(self):
+        """HeadlineEvent supports optional language field."""
+        e = events.HeadlineEvent(
+            title="Test",
+            source="Test",
+            timestamp="12:00",
+            language="ja",
+        )
+        assert e.language == "ja"
+
+
+class TestFrameTickEvent:
+    """Tests for FrameTickEvent dataclass."""
+
+    def test_create_frame_tick_event(self):
+        """FrameTickEvent can be created."""
+        now = datetime.now()
+        e = events.FrameTickEvent(
+            frame_number=100,
+            timestamp=now,
+            delta_seconds=0.05,
+        )
+        assert e.frame_number == 100
+        assert e.timestamp == now
+        assert e.delta_seconds == 0.05
+
+
+class TestMicLevelEvent:
+    """Tests for MicLevelEvent dataclass."""
+
+    def test_create_mic_level_event(self):
+        """MicLevelEvent can be created."""
+        now = datetime.now()
+        e = events.MicLevelEvent(
+            db_level=60.0,
+            excess_above_threshold=10.0,
+            timestamp=now,
+        )
+        assert e.db_level == 60.0
+        assert e.excess_above_threshold == 10.0
+
+
+class TestNtfyMessageEvent:
+    """Tests for NtfyMessageEvent dataclass."""
+
+    def test_create_ntfy_message_event(self):
+        """NtfyMessageEvent can be created with required fields."""
+        e = events.NtfyMessageEvent(
+            title="Test Title",
+            body="Test Body",
+        )
+        assert e.title == "Test Title"
+        assert e.body == "Test Body"
+        assert e.message_id is None
+
+    def test_ntfy_message_event_with_id(self):
+        """NtfyMessageEvent supports optional message_id."""
+        e = events.NtfyMessageEvent(
+            title="Test",
+            body="Test",
+            message_id="abc123",
+        )
+        assert e.message_id == "abc123"
+
+
+class TestStreamEvent:
+    """Tests for StreamEvent dataclass."""
+
+    def test_create_stream_event(self):
+        """StreamEvent can be created."""
+        e = events.StreamEvent(
+            event_type=events.EventType.STREAM_START,
+            headline_count=100,
+        )
+        assert e.event_type == events.EventType.STREAM_START
+        assert e.headline_count == 100

tests/test_frame.py

@@ -0,0 +1,63 @@
+"""
+Tests for engine.frame module.
+"""
+
+import time
+
+from engine.frame import FrameTimer, calculate_scroll_step
+
+
+class TestFrameTimer:
+    """Tests for FrameTimer class."""
+
+    def test_init_default(self):
+        """FrameTimer initializes with default values."""
+        timer = FrameTimer()
+        assert timer.target_frame_dt == 0.05
+        assert timer.fps >= 0
+
+    def test_init_custom(self):
+        """FrameTimer accepts custom frame duration."""
+        timer = FrameTimer(target_frame_dt=0.1)
+        assert timer.target_frame_dt == 0.1
+
+    def test_fps_calculation(self):
+        """FrameTimer calculates FPS correctly."""
+        timer = FrameTimer()
+        timer._frame_count = 10
+        timer._start_time = time.monotonic() - 1.0
+        assert timer.fps >= 9.0
+
+    def test_reset(self):
+        """FrameTimer.reset() clears frame count."""
+        timer = FrameTimer()
+        timer._frame_count = 100
+        timer.reset()
+        assert timer._frame_count == 0
+
+
+class TestCalculateScrollStep:
+    """Tests for calculate_scroll_step function."""
+
+    def test_basic_calculation(self):
+        """calculate_scroll_step returns positive value."""
+        result = calculate_scroll_step(5.0, 24)
+        assert result > 0
+
+    def test_with_padding(self):
+        """calculate_scroll_step respects padding parameter."""
+        without_padding = calculate_scroll_step(5.0, 24, padding=0)
+        with_padding = calculate_scroll_step(5.0, 24, padding=15)
+        assert with_padding < without_padding
+
+    def test_larger_view_slower_scroll(self):
+        """Larger view height results in slower scroll steps."""
+        small = calculate_scroll_step(5.0, 10)
+        large = calculate_scroll_step(5.0, 50)
+        assert large < small
+
+    def test_longer_duration_slower_scroll(self):
+        """Longer scroll duration results in slower scroll steps."""
+        fast = calculate_scroll_step(2.0, 24)
+        slow = calculate_scroll_step(10.0, 24)
+        assert slow > fast

tests/test_layers.py

@@ -0,0 +1,96 @@
+"""
+Tests for engine.layers module.
+"""
+
+import time
+
+from engine import layers
+
+
+class TestRenderMessageOverlay:
+    """Tests for render_message_overlay function."""
+
+    def test_no_message_returns_empty(self):
+        """Returns empty list when msg is None."""
+        result, cache = layers.render_message_overlay(None, 80, 24, (None, None))
+        assert result == []
+        assert cache[0] is None
+
+    def test_message_returns_overlay_lines(self):
+        """Returns non-empty list when message is present."""
+        msg = ("Test Title", "Test Body", time.monotonic())
+        result, cache = layers.render_message_overlay(msg, 80, 24, (None, None))
+        assert len(result) > 0
+        assert cache[0] is not None
+
+    def test_cache_key_changes_with_text(self):
+        """Cache key changes when message text changes."""
+        msg1 = ("Title1", "Body1", time.monotonic())
+        msg2 = ("Title2", "Body2", time.monotonic())
+
+        _, cache1 = layers.render_message_overlay(msg1, 80, 24, (None, None))
+        _, cache2 = layers.render_message_overlay(msg2, 80, 24, cache1)
+
+        assert cache1[0] != cache2[0]
+
+    def test_cache_reuse_avoids_recomputation(self):
+        """Cache is returned when same message is passed (interface test)."""
+        msg = ("Same Title", "Same Body", time.monotonic())
+
+        result1, cache1 = layers.render_message_overlay(msg, 80, 24, (None, None))
+        result2, cache2 = layers.render_message_overlay(msg, 80, 24, cache1)
+
+        assert len(result1) > 0
+        assert len(result2) > 0
+        assert cache1[0] == cache2[0]
+
+
+class TestRenderFirehose:
+    """Tests for render_firehose function."""
+
+    def test_no_firehose_returns_empty(self):
+        """Returns empty list when firehose height is 0."""
+        items = [("Headline", "Source", "12:00")]
+        result = layers.render_firehose(items, 80, 0, 24)
+        assert result == []
+
+    def test_firehose_returns_lines(self):
+        """Returns lines when firehose height > 0."""
+        items = [("Headline", "Source", "12:00")]
+        result = layers.render_firehose(items, 80, 4, 24)
+        assert len(result) == 4
+
+    def test_firehose_includes_ansi_escapes(self):
+        """Returns lines containing ANSI escape sequences."""
+        items = [("Headline", "Source", "12:00")]
+        result = layers.render_firehose(items, 80, 1, 24)
+        assert "\033[" in result[0]
+
+
+class TestApplyGlitch:
+    """Tests for apply_glitch function."""
+
+    def test_empty_buffer_unchanged(self):
+        """Empty buffer is returned unchanged."""
+        result = layers.apply_glitch([], 0, 0.0, 80)
+        assert result == []
+
+    def test_buffer_length_preserved(self):
+        """Buffer length is preserved after glitch application."""
+        buf = [f"\033[{i + 1};1Htest\033[K" for i in range(10)]
+        result = layers.apply_glitch(buf, 0, 0.5, 80)
+        assert len(result) == len(buf)
+
+
+class TestRenderTickerZone:
+    """Tests for render_ticker_zone function - focusing on interface."""
+
+    def test_returns_list(self):
+        """Returns a list of strings."""
+        result, cache = layers.render_ticker_zone([], 0, 10, 80, {}, 0.0)
+        assert isinstance(result, list)
+
+    def test_returns_dict_for_cache(self):
+        """Returns a dict for the noise cache."""
+        result, cache = layers.render_ticker_zone([], 0, 10, 80, {}, 0.0)
+        assert isinstance(cache, dict)

tests/test_mic.py

@@ -2,8 +2,11 @@
 Tests for engine.mic module.
 """
 
+from datetime import datetime
 from unittest.mock import patch
 
+from engine.events import MicLevelEvent
+
 
 class TestMicMonitorImport:
     """Tests for module import behavior."""
@@ -81,3 +84,66 @@ class TestMicMonitorStop:
         monitor = MicMonitor()
         monitor.stop()
         assert monitor._stream is None
+
+
+class TestMicMonitorEventEmission:
+    """Tests for MicMonitor event emission."""
+
+    def test_subscribe_adds_callback(self):
+        """subscribe() adds a callback."""
+        from engine.mic import MicMonitor
+
+        monitor = MicMonitor()
+        def callback(e):
+            return None
+
+        monitor.subscribe(callback)
+
+        assert callback in monitor._subscribers
+
+    def test_unsubscribe_removes_callback(self):
+        """unsubscribe() removes a callback."""
+        from engine.mic import MicMonitor
+
+        monitor = MicMonitor()
+        def callback(e):
+            return None
+        monitor.subscribe(callback)
+
+        monitor.unsubscribe(callback)
+
+        assert callback not in monitor._subscribers
+
+    def test_emit_calls_subscribers(self):
+        """_emit() calls all subscribers."""
+        from engine.mic import MicMonitor
+
+        monitor = MicMonitor()
+        received = []
+
+        def callback(event):
+            received.append(event)
+
+        monitor.subscribe(callback)
+        event = MicLevelEvent(
+            db_level=60.0, excess_above_threshold=10.0, timestamp=datetime.now()
+        )
+        monitor._emit(event)
+
+        assert len(received) == 1
+        assert received[0].db_level == 60.0
+
+    def test_emit_handles_subscriber_exception(self):
+        """_emit() handles exceptions in subscribers gracefully."""
+        from engine.mic import MicMonitor
+
+        monitor = MicMonitor()
+
+        def bad_callback(event):
+            raise RuntimeError("test")
+
+        monitor.subscribe(bad_callback)
+        event = MicLevelEvent(
+            db_level=60.0, excess_above_threshold=10.0, timestamp=datetime.now()
+        )
+        monitor._emit(event)

tests/test_ntfy.py

@@ -5,6 +5,7 @@ Tests for engine.ntfy module.
 import time
 from unittest.mock import MagicMock, patch
 
+from engine.events import NtfyMessageEvent
 from engine.ntfy import NtfyPoller
 
 
@@ -68,3 +69,54 @@ class TestNtfyPollerDismiss:
             poller.dismiss()
 
             assert poller._message is None
+
+
+class TestNtfyPollerEventEmission:
+    """Tests for NtfyPoller event emission."""
+
+    def test_subscribe_adds_callback(self):
+        """subscribe() adds a callback."""
+        poller = NtfyPoller("http://example.com/topic")
+        def callback(e):
+            return None
+
+        poller.subscribe(callback)
+
+        assert callback in poller._subscribers
+
+    def test_unsubscribe_removes_callback(self):
+        """unsubscribe() removes a callback."""
+        poller = NtfyPoller("http://example.com/topic")
+        def callback(e):
+            return None
+        poller.subscribe(callback)
+
+        poller.unsubscribe(callback)
+
+        assert callback not in poller._subscribers
+
+    def test_emit_calls_subscribers(self):
+        """_emit() calls all subscribers."""
+        poller = NtfyPoller("http://example.com/topic")
+        received = []
+
+        def callback(event):
+            received.append(event)
+
+        poller.subscribe(callback)
+        event = NtfyMessageEvent(title="Test", body="Body")
+        poller._emit(event)
+
+        assert len(received) == 1
+        assert received[0].title == "Test"
+
+    def test_emit_handles_subscriber_exception(self):
+        """_emit() handles exceptions in subscribers gracefully."""
+        poller = NtfyPoller("http://example.com/topic")
+
+        def bad_callback(event):
+            raise RuntimeError("test")
+
+        poller.subscribe(bad_callback)
+        event = NtfyMessageEvent(title="Test", body="Body")
+        poller._emit(event)

tests/test_types.py

@@ -0,0 +1,95 @@
+"""
+Tests for engine.types module.
+"""
+
+from engine.types import (
+    Block,
+    FetchResult,
+    HeadlineItem,
+    items_to_tuples,
+    tuples_to_items,
+)
+
+
+class TestHeadlineItem:
+    """Tests for HeadlineItem dataclass."""
+
+    def test_create_headline_item(self):
+        """Can create HeadlineItem with required fields."""
+        item = HeadlineItem(title="Test", source="Source", timestamp="12:00")
+        assert item.title == "Test"
+        assert item.source == "Source"
+        assert item.timestamp == "12:00"
+
+    def test_to_tuple(self):
+        """to_tuple returns correct tuple."""
+        item = HeadlineItem(title="Test", source="Source", timestamp="12:00")
+        assert item.to_tuple() == ("Test", "Source", "12:00")
+
+    def test_from_tuple(self):
+        """from_tuple creates HeadlineItem from tuple."""
+        item = HeadlineItem.from_tuple(("Test", "Source", "12:00"))
+        assert item.title == "Test"
+        assert item.source == "Source"
+        assert item.timestamp == "12:00"
+
+
+class TestItemsConversion:
+    """Tests for list conversion functions."""
+
+    def test_items_to_tuples(self):
+        """Converts list of HeadlineItem to list of tuples."""
+        items = [
+            HeadlineItem(title="A", source="S", timestamp="10:00"),
+            HeadlineItem(title="B", source="T", timestamp="11:00"),
+        ]
+        result = items_to_tuples(items)
+        assert result == [("A", "S", "10:00"), ("B", "T", "11:00")]
+
+    def test_tuples_to_items(self):
+        """Converts list of tuples to list of HeadlineItem."""
+        tuples = [("A", "S", "10:00"), ("B", "T", "11:00")]
+        result = tuples_to_items(tuples)
+        assert len(result) == 2
+        assert result[0].title == "A"
+        assert result[1].title == "B"
+
+
+class TestFetchResult:
+    """Tests for FetchResult dataclass."""
+
+    def test_create_fetch_result(self):
+        """Can create FetchResult."""
+        items = [HeadlineItem(title="Test", source="Source", timestamp="12:00")]
+        result = FetchResult(items=items, linked=1, failed=0)
+        assert len(result.items) == 1
+        assert result.linked == 1
+        assert result.failed == 0
+
+    def test_to_legacy_tuple(self):
+        """to_legacy_tuple returns correct format."""
+        items = [HeadlineItem(title="Test", source="Source", timestamp="12:00")]
+        result = FetchResult(items=items, linked=1, failed=0)
+        legacy = result.to_legacy_tuple()
+        assert legacy[0] == [("Test", "Source", "12:00")]
+        assert legacy[1] == 1
+        assert legacy[2] == 0
+
+
+class TestBlock:
+    """Tests for Block dataclass."""
+
+    def test_create_block(self):
+        """Can create Block."""
+        block = Block(
+            content=["line1", "line2"], color="\033[38;5;46m", meta_row_index=1
+        )
+        assert len(block.content) == 2
+        assert block.color == "\033[38;5;46m"
+        assert block.meta_row_index == 1
+
+    def test_to_legacy_tuple(self):
+        """to_legacy_tuple returns correct format."""
+        block = Block(content=["line1"], color="green", meta_row_index=0)
+        legacy = block.to_legacy_tuple()
+        assert legacy == (["line1"], "green", 0)

tests/test_viewport.py

@@ -0,0 +1,64 @@
+"""
+Tests for engine.viewport module.
+"""
+
+from engine import viewport
+
+
+class TestViewportTw:
+    """Tests for tw() function."""
+
+    def test_tw_returns_int(self):
+        """tw() returns an integer."""
+        result = viewport.tw()
+        assert isinstance(result, int)
+
+    def test_tw_positive(self):
+        """tw() returns a positive value."""
+        assert viewport.tw() > 0
+
+
+class TestViewportTh:
+    """Tests for th() function."""
+
+    def test_th_returns_int(self):
+        """th() returns an integer."""
+        result = viewport.th()
+        assert isinstance(result, int)
+
+    def test_th_positive(self):
+        """th() returns a positive value."""
+        assert viewport.th() > 0
+
+
+class TestViewportMoveTo:
+    """Tests for move_to() function."""
+
+    def test_move_to_format(self):
+        """move_to() returns correctly formatted ANSI escape."""
+        result = viewport.move_to(5, 10)
+        assert result == "\033[5;10H"
+
+    def test_move_to_default_col(self):
+        """move_to() defaults to column 1."""
+        result = viewport.move_to(5)
+        assert result == "\033[5;1H"
+
+
+class TestViewportClearScreen:
+    """Tests for clear_screen() function."""
+
+    def test_clear_screen_format(self):
+        """clear_screen() returns clear screen ANSI escape."""
+        result = viewport.clear_screen()
+        assert "\033[2J" in result
+        assert "\033[H" in result
+
+
+class TestViewportClearLine:
+    """Tests for clear_line() function."""
+
+    def test_clear_line_format(self):
+        """clear_line() returns clear line ANSI escape."""
+        result = viewport.clear_line()
+        assert result == "\033[K"