diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 92bb8078..f576aa10 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -539,6 +539,11 @@ jobs:
           fi
           "$PYTHON" -m pip install ..[yubikey]
 
+      - name: Run unit tests
+        run: |
+          "$PYTHON" -m pip install pytest
+          "$PYTHON" -m pytest ../tests/ -v
+
       - name: Install PyInstaller
         if: matrix.goal == 'build'
         run: |
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 00000000..5ee64771
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,2 @@
+[pytest]
+testpaths = tests
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 00000000..cabb3633
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,63 @@
+"""Pytest configuration and shared fixtures for GAM tests.
+
+Path setup: GAM's modules use bare 'from util.X import ...' which requires the
+gam package directory on sys.path. We add it in a fixture (not at module level)
+to avoid shadowing Python's stdlib 'cmd' module during pytest configuration.
+"""
+
+import os
+import sys
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def _gam_path_and_globals():
+    """Add GAM's package dir to sys.path and initialize minimal global state.
+
+    Done in a fixture rather than at module level to avoid polluting sys.path
+    during pytest's own import of stdlib modules (e.g. cmd, which would collide
+    with gam/cmd/).
+    """
+    gam_pkg_dir = os.path.join(os.path.dirname(__file__), '..', 'src', 'gam')
+    gam_pkg_dir = os.path.normpath(gam_pkg_dir)
+
+    # Temporarily prepend — will be cleaned up after test
+    inserted = False
+    if gam_pkg_dir not in sys.path:
+        sys.path.insert(0, gam_pkg_dir)
+        inserted = True
+
+    # Also need src/ on path for 'gam' package imports
+    src_dir = os.path.join(os.path.dirname(__file__), '..', 'src')
+    src_dir = os.path.normpath(src_dir)
+    src_inserted = False
+    if src_dir not in sys.path:
+        sys.path.insert(0, src_dir)
+        src_inserted = True
+
+    from gamlib import glcfg as GC
+    from gamlib import glglobals as GM
+
+    # Ensure Values dict exists with minimal defaults
+    if not GC.Values:
+        GC.Values = {}
+    GC.Values.setdefault(GC.DOMAIN, 'example.com')
+    GC.Values.setdefault(GC.CUSTOMER_ID, 'C00000000')
+    GC.Values.setdefault(GC.TIMEZONE, 'UTC')
+    GC.Values.setdefault(GC.SHOW_COUNTS_MIN, 0)
+
+    # Ensure Globals dict exists
+    if not GM.Globals:
+        GM.Globals = {}
+    GM.Globals.setdefault(GM.STDOUT, None)
+    GM.Globals.setdefault(GM.STDERR, None)
+    GM.Globals.setdefault(GM.SYSEXITRC, 0)
+
+    yield
+
+    # Clean up sys.path to avoid side effects between test files
+    if inserted and gam_pkg_dir in sys.path:
+        sys.path.remove(gam_pkg_dir)
+    if src_inserted and src_dir in sys.path:
+        sys.path.remove(src_dir)
diff --git a/tests/test_args.py b/tests/test_args.py
new file mode 100644
index 00000000..a19afa50
--- /dev/null
+++ b/tests/test_args.py
@@ -0,0 +1,181 @@
+"""Unit tests for gam.util.args — argument parsing and formatting functions."""
+
+import pytest
+import arrow
+
+
+class TestCourseScopes:
+    """Test course ID and alias scope manipulation."""
+
+    def test_add_course_id_scope_plain(self):
+        from gam.util.args import addCourseIdScope
+        assert addCourseIdScope('12345') == '12345'  # numeric, no prefix
+
+    def test_add_course_id_scope_name(self):
+        from gam.util.args import addCourseIdScope
+        assert addCourseIdScope('my-course') == 'd:my-course'
+
+    def test_add_course_id_scope_already_prefixed(self):
+        from gam.util.args import addCourseIdScope
+        assert addCourseIdScope('d:my-course') == 'd:my-course'
+        assert addCourseIdScope('p:my-course') == 'p:my-course'
+
+    def test_remove_course_id_scope(self):
+        from gam.util.args import removeCourseIdScope
+        assert removeCourseIdScope('d:my-course') == 'my-course'
+
+    def test_remove_course_id_scope_no_prefix(self):
+        from gam.util.args import removeCourseIdScope
+        assert removeCourseIdScope('12345') == '12345'
+
+    def test_add_course_alias_scope(self):
+        from gam.util.args import addCourseAliasScope
+        assert addCourseAliasScope('my-alias') == 'd:my-alias'
+
+    def test_add_course_alias_scope_already_prefixed(self):
+        from gam.util.args import addCourseAliasScope
+        assert addCourseAliasScope('d:my-alias') == 'd:my-alias'
+        assert addCourseAliasScope('p:my-alias') == 'p:my-alias'
+
+    def test_remove_course_alias_scope(self):
+        from gam.util.args import removeCourseAliasScope
+        assert removeCourseAliasScope('d:my-alias') == 'my-alias'
+
+    def test_remove_course_alias_scope_no_prefix(self):
+        from gam.util.args import removeCourseAliasScope
+        assert removeCourseAliasScope('my-alias') == 'my-alias'
+
+
+class TestEmailAddressParsing:
+    """Test email address parsing and normalization."""
+
+    def test_get_email_domain(self):
+        from gam.util.args import getEmailAddressDomain
+        assert getEmailAddressDomain('user@domain.com') == 'domain.com'
+
+    def test_get_email_domain_no_at(self):
+        from gam.util.args import getEmailAddressDomain
+        # Falls back to GC.Values[GC.DOMAIN] which is 'example.com' in conftest
+        assert getEmailAddressDomain('justuser') == 'example.com'
+
+    def test_get_email_domain_case(self):
+        from gam.util.args import getEmailAddressDomain
+        assert getEmailAddressDomain('user@DOMAIN.COM') == 'domain.com'
+
+    def test_get_email_username(self):
+        from gam.util.args import getEmailAddressUsername
+        assert getEmailAddressUsername('user@domain.com') == 'user'
+
+    def test_get_email_username_no_at(self):
+        from gam.util.args import getEmailAddressUsername
+        assert getEmailAddressUsername('justuser') == 'justuser'
+
+    def test_split_email(self):
+        from gam.util.args import splitEmailAddress
+        assert splitEmailAddress('User@Domain.COM') == ('user', 'domain.com')
+
+    def test_split_email_no_at(self):
+        from gam.util.args import splitEmailAddress
+        assert splitEmailAddress('JustUser') == ('justuser', 'example.com')
+
+    def test_normalize_uid(self):
+        from gam.util.args import normalizeEmailAddressOrUID
+        # uid: prefix should be stripped
+        assert normalizeEmailAddressOrUID('uid:12345') == '12345'
+
+    def test_normalize_email_lowercased(self):
+        from gam.util.args import normalizeEmailAddressOrUID
+        result = normalizeEmailAddressOrUID('User@Domain.COM')
+        assert result == 'user@domain.com'
+
+    def test_normalize_email_no_lower(self):
+        from gam.util.args import normalizeEmailAddressOrUID
+        result = normalizeEmailAddressOrUID('User@Domain.COM', noLower=True)
+        assert result == 'User@Domain.COM'
+
+    def test_normalize_bare_username_gets_domain(self):
+        from gam.util.args import normalizeEmailAddressOrUID
+        result = normalizeEmailAddressOrUID('admin')
+        assert result == 'admin@example.com'
+
+
+class TestFormatting:
+    """Test formatting helper functions."""
+
+    def test_format_milliseconds(self):
+        from gam.util.args import formatMilliSeconds
+        assert formatMilliSeconds(0) == '00:00:00'
+        assert formatMilliSeconds(1000) == '00:00:01'
+        assert formatMilliSeconds(61000) == '00:01:01'
+        assert formatMilliSeconds(3661000) == '01:01:01'
+
+    def test_format_http_error(self):
+        from gam.util.args import formatHTTPError
+        result = formatHTTPError(404, 'Not Found', 'Resource missing')
+        assert result == '404: Not Found - Resource missing'
+
+    def test_format_max_message_bytes_raw(self):
+        from gam.util.args import formatMaxMessageBytes
+        assert formatMaxMessageBytes(500, 1024, 1048576) == 500
+
+    def test_format_max_message_bytes_kilobytes(self):
+        from gam.util.args import formatMaxMessageBytes
+        assert formatMaxMessageBytes(2048, 1024, 1048576) == '2K'
+
+    def test_format_max_message_bytes_megabytes(self):
+        from gam.util.args import formatMaxMessageBytes
+        assert formatMaxMessageBytes(5242880, 1024, 1048576) == '5M'
+
+    def test_format_file_size_zero(self):
+        from gam.util.args import formatFileSize
+        assert formatFileSize(0) == '0 KB'
+
+    def test_format_file_size_small(self):
+        from gam.util.args import formatFileSize
+        assert formatFileSize(500) == '1 KB'
+
+
+class TestTimestamps:
+    """Test timestamp formatting."""
+
+    def test_iso_format_timestamp(self):
+        from gam.util.output import ISOformatTimeStamp
+        ts = arrow.get('2024-01-15T10:30:00+00:00')
+        result = ISOformatTimeStamp(ts)
+        assert '2024-01-15' in result
+        assert '10:30:00' in result
+
+    def test_current_iso_format_returns_string(self):
+        from gam.util.output import currentISOformatTimeStamp
+        result = currentISOformatTimeStamp()
+        assert isinstance(result, str)
+        assert 'T' in result  # ISO format contains T separator
+
+
+class TestDeltaParsing:
+    """Test time delta parsing functions."""
+
+    def test_get_delta_invalid_returns_none(self):
+        from gam.util.args import getDelta, DELTA_DATE_PATTERN
+        result = getDelta('not-a-delta', DELTA_DATE_PATTERN)
+        assert result is None
+
+    def test_get_delta_date(self):
+        """Requires GM.DATETIME_NOW to be initialized."""
+        import arrow as _arrow
+        from gamlib import glglobals as GM
+        GM.Globals[GM.DATETIME_NOW] = _arrow.now()
+
+        from gam.util.args import getDeltaDate
+        result = getDeltaDate('-30d')
+        assert result is not None
+
+    def test_get_delta_time(self):
+        """Requires GM.DATETIME_NOW to be initialized."""
+        import arrow as _arrow
+        from gamlib import glglobals as GM
+        GM.Globals[GM.DATETIME_NOW] = _arrow.now()
+
+        from gam.util.args import getDeltaTime
+        result = getDeltaTime('-1h')
+        assert result is not None
diff --git a/tests/test_imports.py b/tests/test_imports.py
new file mode 100644
index 00000000..65d104a6
--- /dev/null
+++ b/tests/test_imports.py
@@ -0,0 +1,62 @@
+"""Structural tests — verify all modules import without errors."""
+
+import importlib
+import os
+import sys
+
+import pytest
+
+
+class TestAllModulesImport:
+    """Every module in gam/ should import without errors."""
+
+    def test_gam_package_imports(self):
+        """The top-level gam package should import without circular import errors."""
+        import gam
+        assert hasattr(gam, 'ProcessGAMCommand')
+
+    def test_util_modules_import(self):
+        """All util/ modules should import individually without errors."""
+        util_dir = os.path.join(os.path.dirname(__file__), '..', 'src', 'gam', 'util')
+        util_dir = os.path.normpath(util_dir)
+
+        failures = []
+        for f in sorted(os.listdir(util_dir)):
+            if not f.endswith('.py') or f == '__init__.py':
+                continue
+            mod_name = f'gam.util.{f[:-3]}'
+            try:
+                importlib.import_module(mod_name)
+            except Exception as e:
+                failures.append(f'{mod_name}: {e}')
+
+        assert not failures, "Failed to import:\n" + "\n".join(failures)
+
+    def test_no_local_imports_in_util(self):
+        """util/ modules should not have function-scope imports from other util/ modules.
+
+        The one known exception is api.py:getSaUser (documented api<->uid cycle).
+        """
+        import re
+        util_dir = os.path.join(os.path.dirname(__file__), '..', 'src', 'gam', 'util')
+        util_dir = os.path.normpath(util_dir)
+
+        KNOWN_EXCEPTIONS = {
+            ('api.py', 'from util.uid import convertUIDtoEmailAddress'),
+        }
+
+        violations = []
+        for f in sorted(os.listdir(util_dir)):
+            if not f.endswith('.py') or f == '__init__.py':
+                continue
+            with open(os.path.join(util_dir, f)) as fh:
+                for i, line in enumerate(fh, 1):
+                    if re.match(r'^\s+from (util|gam\.util)\.\w+ import', line):
+                        text = line.strip().split('#')[0].strip()
+                        if (f, text) not in KNOWN_EXCEPTIONS:
+                            violations.append(f'{f}:{i}: {line.strip()}')
+
+        assert not violations, (
+            f"Found {len(violations)} unexpected local import(s) in util/:\n"
+            + "\n".join(violations)
+        )
diff --git a/tests/test_output.py b/tests/test_output.py
new file mode 100644
index 00000000..d4332e57
--- /dev/null
+++ b/tests/test_output.py
@@ -0,0 +1,99 @@
+"""Unit tests for gam.util.output — output formatting and utility functions."""
+
+import pytest
+
+
+class TestStripControlChars:
+    """Test control character stripping."""
+
+    def test_strips_null(self):
+        from gam.util.output import _stripControlCharsFromName
+        assert _stripControlCharsFromName('hello\x00world') == 'helloworld'
+
+    def test_strips_cr(self):
+        from gam.util.output import _stripControlCharsFromName
+        assert _stripControlCharsFromName('hello\rworld') == 'helloworld'
+
+    def test_strips_nl(self):
+        from gam.util.output import _stripControlCharsFromName
+        assert _stripControlCharsFromName('hello\nworld') == 'helloworld'
+
+    def test_strips_multiple(self):
+        from gam.util.output import _stripControlCharsFromName
+        assert _stripControlCharsFromName('\x00he\rll\no') == 'hello'
+
+    def test_clean_string_unchanged(self):
+        from gam.util.output import _stripControlCharsFromName
+        assert _stripControlCharsFromName('hello world') == 'hello world'
+
+    def test_empty_string(self):
+        from gam.util.output import _stripControlCharsFromName
+        assert _stripControlCharsFromName('') == ''
+
+
+class TestCurrentCount:
+    """Test count display formatting."""
+
+    def test_current_count_with_items(self):
+        from gam.util.output import currentCount
+        result = currentCount(3, 10)
+        assert result == ' (3/10)'
+
+    def test_current_count_nl(self):
+        from gam.util.output import currentCountNL
+        result = currentCountNL(3, 10)
+        assert result == ' (3/10)\n'
+
+
+class TestFormatKeyValueList:
+    """Test key-value list formatting.
+
+    formatKeyValueList processes pairs: [key1, val1, key2, val2, ...]
+    Each key gets ': ' and its value appended.
+    """
+
+    def test_single_pair(self):
+        from gam.util.output import formatKeyValueList
+        result = formatKeyValueList('', ['Name', 'Alice'], '')
+        assert result == 'Name: Alice'
+
+    def test_multiple_pairs(self):
+        from gam.util.output import formatKeyValueList
+        result = formatKeyValueList('', ['Name', 'Alice', 'Age', 30], '')
+        assert 'Name: Alice' in result
+        assert 'Age: 30' in result
+
+    def test_with_prefix_suffix(self):
+        from gam.util.output import formatKeyValueList
+        result = formatKeyValueList('  ', ['key', 'val'], '\n')
+        assert result == '  key: val\n'
+
+    def test_none_value(self):
+        from gam.util.output import formatKeyValueList
+        result = formatKeyValueList('', ['key', None], '')
+        assert result == 'key:'
+
+    def test_empty_list(self):
+        from gam.util.output import formatKeyValueList
+        result = formatKeyValueList('pre', [], 'suf')
+        assert result == 'presuf'
+
+
+class TestColoredText:
+    """Test colored text creation."""
+
+    def test_create_colored_text_returns_string(self):
+        from gam.util.output import createColoredText
+        result = createColoredText('hello', 'red')
+        assert isinstance(result, str)
+        assert 'hello' in result
+
+    def test_create_red_text(self):
+        from gam.util.output import createRedText
+        result = createRedText('error')
+        assert 'error' in result
+
+    def test_create_green_text(self):
+        from gam.util.output import createGreenText
+        result = createGreenText('success')
+        assert 'success' in result