diff --git a/tests/e2e/models.py b/tests/e2e/models.py
new file mode 100644
index 0000000..e9f003e
--- /dev/null
+++ b/tests/e2e/models.py
@@ -0,0 +1,41 @@
+"""Shared data models for the Peregrine E2E test harness."""
+from __future__ import annotations
+import fnmatch
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Callable, Any
+
+
+@dataclass(frozen=True)
+class ErrorRecord:
+    type: str       # "exception" | "alert"
+    message: str
+    element_html: str
+
+    def __eq__(self, other: object) -> bool:
+        if not isinstance(other, ErrorRecord):
+            return NotImplemented
+        return (self.type, self.message) == (other.type, other.message)
+
+    def __hash__(self) -> int:
+        return hash((self.type, self.message))
+
+
+def diff_errors(before: list[ErrorRecord], after: list[ErrorRecord]) -> list[ErrorRecord]:
+    """Return errors in `after` that were not present in `before`."""
+    before_set = set(before)
+    return [e for e in after if e not in before_set]
+
+
+@dataclass
+class ModeConfig:
+    name: str
+    base_url: str
+    auth_setup: Callable[[Any], None]
+    expected_failures: list[str]        # fnmatch glob patterns against element labels
+    results_dir: Path | None
+    settings_tabs: list[str]            # tabs expected per mode
+
+    def matches_expected_failure(self, label: str) -> bool:
+        """Return True if label matches any expected_failure pattern (fnmatch)."""
+        return any(fnmatch.fnmatch(label, pattern) for pattern in self.expected_failures)
diff --git a/tests/test_e2e_helpers.py b/tests/test_e2e_helpers.py
new file mode 100644
index 0000000..e07706d
--- /dev/null
+++ b/tests/test_e2e_helpers.py
@@ -0,0 +1,64 @@
+"""Unit tests for E2E harness models and helper utilities."""
+import fnmatch
+import pytest
+from unittest.mock import patch, MagicMock
+import time
+from tests.e2e.models import ErrorRecord, ModeConfig, diff_errors
+
+
+def test_error_record_equality():
+    a = ErrorRecord(type="exception", message="boom", element_html="<div>boom</div>")
+    b = ErrorRecord(type="exception", message="boom", element_html="<div>boom</div>")
+    assert a == b
+
+
+def test_error_record_inequality():
+    a = ErrorRecord(type="exception", message="boom", element_html="")
+    b = ErrorRecord(type="alert", message="boom", element_html="")
+    assert a != b
+
+
+def test_diff_errors_returns_new_only():
+    before = [ErrorRecord("exception", "old error", "")]
+    after = [
+        ErrorRecord("exception", "old error", ""),
+        ErrorRecord("alert", "new error", ""),
+    ]
+    result = diff_errors(before, after)
+    assert result == [ErrorRecord("alert", "new error", "")]
+
+
+def test_diff_errors_empty_when_no_change():
+    errors = [ErrorRecord("exception", "x", "")]
+    assert diff_errors(errors, errors) == []
+
+
+def test_diff_errors_empty_before():
+    after = [ErrorRecord("alert", "boom", "")]
+    assert diff_errors([], after) == after
+
+
+def test_mode_config_expected_failure_match():
+    config = ModeConfig(
+        name="demo",
+        base_url="http://localhost:8504",
+        auth_setup=lambda ctx: None,
+        expected_failures=["Fetch*", "Generate Cover Letter"],
+        results_dir=None,
+        settings_tabs=["👤 My Profile"],
+    )
+    assert config.matches_expected_failure("Fetch New Jobs")
+    assert config.matches_expected_failure("Generate Cover Letter")
+    assert not config.matches_expected_failure("View Jobs")
+
+
+def test_mode_config_no_expected_failures():
+    config = ModeConfig(
+        name="local",
+        base_url="http://localhost:8502",
+        auth_setup=lambda ctx: None,
+        expected_failures=[],
+        results_dir=None,
+        settings_tabs=[],
+    )
+    assert not config.matches_expected_failure("Fetch New Jobs")