diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 309e07d..59eda22 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -57,6 +57,7 @@ jobs:
           uv run coverage erase
           uv run coverage run -m pytest
           uv run coverage report
+          uv run coverage xml
       - name: Upload coverage data
         if: always()
         uses: actions/upload-artifact@v7
@@ -66,6 +67,11 @@ jobs:
           include-hidden-files: true
           if-no-files-found: error
           retention-days: 7
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v6
+        with:
+          files: coverage.xml
+          fail_ci_if_error: false
 
   build:
     name: Build & audit package
diff --git a/.gitignore b/.gitignore
index f61d98c..2148e53 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,6 +21,7 @@ build/
 .pytest_cache/
 .tox/
 .coverage
+coverage.xml
 htmlcov/
 .mypy_cache/
 .ruff_cache/
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..066661e
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,23 @@
+# Mirrors the lint job in .github/workflows/ci.yml (ruff check, ruff format,
+# mypy) so contributors get the same checks locally before pushing.
+repos:
+  - repo: local
+    hooks:
+      - id: ruff-check
+        name: ruff check
+        entry: uv run ruff check .
+        language: system
+        types: [python]
+        pass_filenames: false
+      - id: ruff-format
+        name: ruff format
+        entry: uv run ruff format --check .
+        language: system
+        types: [python]
+        pass_filenames: false
+      - id: mypy
+        name: mypy type check
+        entry: uv run mypy gcode
+        language: system
+        types: [python]
+        pass_filenames: false
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 773c79d..c6a8875 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -46,6 +46,21 @@ Look for issues labeled [`good first issue`](https://github.com/shauryagangrade/
 - Write clean, readable code with descriptive variable names.
 - Ensure all tests pass before opening a PR.
 
+## Pre-commit Hooks
+
+Install the hooks once so lint, formatting, and type checks run before every
+commit (they mirror the CI lint job):
+
+```bash
+uv run pre-commit install
+```
+
+Run them on the whole tree any time with:
+
+```bash
+uv run pre-commit run --all-files
+```
+
 ---
 
 ## PR Guidelines
diff --git a/README.md b/README.md
index 907536a..6efe1f4 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # GCode
 
 ![Build](https://github.com/shauryagangrade/GCode/actions/workflows/ci.yml/badge.svg)
+[![codecov](https://codecov.io/gh/shauryagangrade/GCode/branch/main/graph/badge.svg)](https://codecov.io/gh/shauryagangrade/GCode)
 [![License: Apache 2.0](https://img.shields.io/badge/license-Apache%202.0-blue.svg)](LICENSE)
 [![PyPI version](https://img.shields.io/pypi/v/gcode.svg)](https://pypi.org/project/gcode/)
 [![Stars](https://img.shields.io/github/stars/shauryagangrade/GCode?style=social)](https://github.com/shauryagangrade/GCode)
diff --git a/pyproject.toml b/pyproject.toml
index 05e3ebc..53edb71 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,6 +20,7 @@ dev = [
     "coverage>=7",
     "mypy>=1.13",
     "pip-audit>=2.7",
+    "pre-commit>=4.0",
     "pytest>=8",
     "ruff>=0.9",
 ]
diff --git a/tests/test_ui.py b/tests/test_ui.py
index 44ccb9c..46e3bfc 100644
--- a/tests/test_ui.py
+++ b/tests/test_ui.py
@@ -1,4 +1,6 @@
-from gcode.ui import RichUI
+from unittest.mock import Mock, patch
+
+from gcode.ui import RichUI, _summarize_tool, _truncate
 from rich.console import Console
 
 
@@ -13,3 +15,151 @@ def test_goodbye_renders_logo_and_session():
     assert "Thanks for coding with GCode." in output
     assert "session" in output.lower()
     assert "demo-session" in output
+
+
+# -- _truncate -------------------------------------------------------------
+
+
+def test_truncate_short_text_unchanged():
+    assert _truncate("hello world", 50) == "hello world"
+
+
+def test_truncate_normalizes_whitespace():
+    assert _truncate("a   b\n\tc", 50) == "a b c"
+
+
+def test_truncate_long_text_appends_ellipsis():
+    out = _truncate("x" * 100, 80)
+    assert out == "x" * 80 + "…"
+
+
+def test_truncate_exact_limit_no_ellipsis():
+    assert _truncate("x" * 80, 80) == "x" * 80
+
+
+def test_truncate_empty_string():
+    assert _truncate("", 10) == ""
+
+
+def test_truncate_non_string_input():
+    assert _truncate(42, 10) == "42"
+
+
+# -- _summarize_tool -------------------------------------------------------
+
+
+def test_summarize_tool_execute_bash_command():
+    assert _summarize_tool("execute_bash", {"command": "ls -la"}) == "ls -la"
+
+
+def test_summarize_tool_uses_path_when_present():
+    assert _summarize_tool("read_file", {"path": "src/main.py"}) == "src/main.py"
+
+
+def test_summarize_tool_non_string_path_becomes_empty():
+    assert _summarize_tool("read_file", {"path": 123}) == ""
+
+
+def test_summarize_tool_path_wins_over_other_args():
+    assert _summarize_tool("grep", {"pattern": "foo", "path": "src"}) == "src"
+
+
+def test_summarize_tool_empty_args():
+    assert _summarize_tool("noop", {}) == ""
+
+
+def test_summarize_tool_truncates_long_values():
+    out = _summarize_tool("edit_file", {"path": "x" * 500})
+    assert out == "x" * 120 + "…"
+
+
+# -- _show_slash_menu ------------------------------------------------------
+
+
+def _mock_select(return_value):
+    sel = Mock()
+    sel.ask.return_value = return_value
+    return sel
+
+
+def test_slash_menu_returns_selected_command():
+    with patch(
+        "gcode.ui.questionary.select",
+        return_value=_mock_select("/help  — Show available commands"),
+    ) as select_mock:
+        ui = RichUI()
+        assert ui._show_slash_menu() == "/help"
+
+    choices = select_mock.call_args.kwargs["choices"]
+    assert choices[0].startswith("/help")
+
+
+def test_slash_menu_cancel_returns_empty():
+    with patch("gcode.ui.questionary.select", return_value=_mock_select(None)):
+        ui = RichUI()
+        assert ui._show_slash_menu() == ""
+
+
+def test_slash_menu_keyboard_interrupt_returns_empty():
+    sel = Mock()
+    sel.ask.side_effect = KeyboardInterrupt
+    with patch("gcode.ui.questionary.select", return_value=sel):
+        ui = RichUI()
+        assert ui._show_slash_menu() == ""
+
+
+# -- streaming refresh handler ---------------------------------------------
+
+
+class _FakeLive:
+    """Minimal stand-in for rich.live.Live that records updates."""
+
+    def __init__(self):
+        self.updates = []
+        self.stopped = False
+
+    def start(self):
+        pass
+
+    def update(self, content):
+        self.updates.append(content)
+
+    def stop(self):
+        self.stopped = True
+
+
+def test_token_renders_markdown_after_threshold(monkeypatch):
+    from gcode import ui as ui_module
+
+    fake = _FakeLive()
+    monkeypatch.setattr(ui_module, "Live", lambda *args, **kwargs: fake)
+
+    ui = RichUI()
+    ui.assistant_start()
+
+    # Below the 80-char re-render threshold: no update yet.
+    ui.token("x" * 40)
+    assert fake.updates == []
+
+    # Crossing the threshold triggers one Markdown update.
+    ui.token("y" * 50)  # total 90 >= 80
+    assert len(fake.updates) == 1
+
+    # Ending the stream renders the final text and stops the live region.
+    ui.assistant_end()
+    assert fake.stopped
+    assert len(fake.updates) == 2
+
+
+# -- tool display ----------------------------------------------------------
+
+
+def test_tool_start_renders_summary():
+    ui = RichUI()
+    ui.console = Console(record=True, width=120)
+
+    ui.tool_start("execute_bash", {"command": "ls"})
+
+    output = ui.console.export_text()
+    assert "execute_bash" in output
+    assert "ls" in output