diff --git a/scripts/test_reset_pipeline_state.py b/scripts/test_reset_pipeline_state.py
new file mode 100644
index 00000000..83567b9a
--- /dev/null
+++ b/scripts/test_reset_pipeline_state.py
@@ -0,0 +1,190 @@
+#!/usr/bin/env python3
+"""Tests for scripts/reset_pipeline_state.py — 10 tests."""
+
+import json
+import os
+import sys
+import tempfile
+from datetime import datetime, timezone, timedelta
+
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+from reset_pipeline_state import reset_pipeline_state, classify_stale, parse_timestamp
+
+
+def test_no_state_file():
+    """Reset on missing file returns empty."""
+    state, removed = reset_pipeline_state("/nonexistent/pipeline_state.json")
+    assert state == {}
+    assert removed == []
+    print("PASS: test_no_state_file")
+
+
+def test_empty_state():
+    """Empty JSON object is untouched."""
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump({}, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert state == {}
+        assert removed == []
+    finally:
+        os.unlink(path)
+    print("PASS: test_empty_state")
+
+
+def test_fresh_complete_kept():
+    """Recent complete entry is kept."""
+    now = datetime.now(timezone.utc)
+    entry = {"state": "complete", "updated": now.isoformat()}
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump({"my-pipeline": entry}, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert "my-pipeline" in state
+        assert removed == []
+    finally:
+        os.unlink(path)
+    print("PASS: test_fresh_complete_kept")
+
+
+def test_old_complete_removed():
+    """Complete entry older than 24h is removed."""
+    old = (datetime.now(timezone.utc) - timedelta(hours=30)).isoformat()
+    entry = {"state": "complete", "updated": old}
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump({"old-pipeline": entry}, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert "old-pipeline" not in state
+        assert len(removed) == 1
+        assert "old-pipeline" in removed[0]
+    finally:
+        os.unlink(path)
+    print("PASS: test_old_complete_removed")
+
+
+def test_stuck_running_removed():
+    """Running entry older than 6h is treated as stuck and removed."""
+    old = (datetime.now(timezone.utc) - timedelta(hours=10)).isoformat()
+    entry = {"state": "running", "updated": old}
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump({"stuck-pipeline": entry}, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert "stuck-pipeline" not in state
+        assert len(removed) == 1
+    finally:
+        os.unlink(path)
+    print("PASS: test_stuck_running_removed")
+
+
+def test_old_failed_removed():
+    """Failed entry older than 24h is removed."""
+    old = (datetime.now(timezone.utc) - timedelta(hours=48)).isoformat()
+    entry = {"state": "failed", "updated": old}
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump({"failed-pipeline": entry}, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert "failed-pipeline" not in state
+    finally:
+        os.unlink(path)
+    print("PASS: test_old_failed_removed")
+
+
+def test_running_kept_if_fresh():
+    """Fresh running entry is kept."""
+    now = datetime.now(timezone.utc)
+    entry = {"state": "running", "updated": now.isoformat()}
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump({"active-pipeline": entry}, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert "active-pipeline" in state
+        assert removed == []
+    finally:
+        os.unlink(path)
+    print("PASS: test_running_kept_if_fresh")
+
+
+def test_dry_run_does_not_modify():
+    """Dry run reports removals but doesn't change the file."""
+    old = (datetime.now(timezone.utc) - timedelta(hours=30)).isoformat()
+    content = json.dumps({"old-pipeline": {"state": "complete", "updated": old}})
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        f.write(content)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path, dry_run=True)
+        assert "old-pipeline" not in state
+        assert len(removed) == 1
+        # File should be unchanged
+        with open(path) as f:
+            file_state = json.load(f)
+        assert "old-pipeline" in file_state
+    finally:
+        os.unlink(path)
+    print("PASS: test_dry_run_does_not_modify")
+
+
+def test_mixed_entries():
+    """Mix of fresh and stale entries — only stale removed."""
+    now = datetime.now(timezone.utc)
+    old = (now - timedelta(hours=30)).isoformat()
+    state_data = {
+        "fresh-complete": {"state": "complete", "updated": now.isoformat()},
+        "stale-complete": {"state": "complete", "updated": old},
+        "fresh-running": {"state": "running", "updated": now.isoformat()},
+        "stuck-running": {"state": "running", "updated": (now - timedelta(hours=10)).isoformat()},
+    }
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump(state_data, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert "fresh-complete" in state
+        assert "fresh-running" in state
+        assert "stale-complete" not in state
+        assert "stuck-running" not in state
+        assert len(removed) == 2
+    finally:
+        os.unlink(path)
+    print("PASS: test_mixed_entries")
+
+
+def test_corrupted_entry_removed():
+    """Non-dict entries are removed."""
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
+        json.dump({"broken": "not_a_dict", "also-bad": 42}, f)
+        path = f.name
+    try:
+        state, removed = reset_pipeline_state(path)
+        assert "broken" not in state
+        assert "also-bad" not in state
+    finally:
+        os.unlink(path)
+    print("PASS: test_corrupted_entry_removed")
+
+
+def run_all():
+    test_no_state_file()
+    test_empty_state()
+    test_fresh_complete_kept()
+    test_old_complete_removed()
+    test_stuck_running_removed()
+    test_old_failed_removed()
+    test_running_kept_if_fresh()
+    test_dry_run_does_not_modify()
+    test_mixed_entries()
+    test_corrupted_entry_removed()
+    print("\nAll 10 tests passed!")
+
+
+if __name__ == "__main__":
+    run_all()