diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..0c64f4e
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,19 @@
+[project]
+name = "event-taxonomy"
+version = "0.1.0"
+description = "Normalize event naming and structure across analysis tools"
+requires-python = ">=3.13"
+dependencies = []
+
+[project.scripts]
+event-taxonomy = "event_taxonomy.__main__:main"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/event_taxonomy"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
diff --git a/src/event_taxonomy/__init__.py b/src/event_taxonomy/__init__.py
new file mode 100644
index 0000000..465b0f4
--- /dev/null
+++ b/src/event_taxonomy/__init__.py
@@ -0,0 +1,3 @@
+from event_taxonomy.schema import NormalizedFinding, Severity, ToolEvent
+
+__all__ = ["NormalizedFinding", "Severity", "ToolEvent"]
diff --git a/src/event_taxonomy/__main__.py b/src/event_taxonomy/__main__.py
new file mode 100644
index 0000000..a29890f
--- /dev/null
+++ b/src/event_taxonomy/__main__.py
@@ -0,0 +1,32 @@
+"""CLI: reads JSON from stdin, outputs normalized JSON.
+
+Usage:
+    echo '[{...}]' | python -m event_taxonomy --tool bus-factor-analyzer
+    echo '[{...}]' | event-taxonomy --tool dep-risk-scanner
+"""
+
+import argparse
+import json
+import sys
+
+from event_taxonomy.registry import list_tools, normalize_output
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Normalize tool findings to canonical schema")
+    parser.add_argument("--tool", required=True, help=f"Tool name. Options: {', '.join(list_tools())}")
+    parser.add_argument("--version", default="unknown", help="Tool version string")
+    parser.add_argument("--indent", type=int, default=2, help="JSON indent (0 for compact)")
+    args = parser.parse_args()
+
+    raw = json.load(sys.stdin)
+    if isinstance(raw, dict):
+        raw = [raw]
+
+    event = normalize_output(args.tool, raw, tool_version=args.version)
+    indent = args.indent if args.indent > 0 else None
+    print(event.to_json(indent=indent))
+
+
+if __name__ == "__main__":
+    main()
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diff --git a/src/event_taxonomy/adapters/_severity.py b/src/event_taxonomy/adapters/_severity.py
new file mode 100644
index 0000000..537e632
--- /dev/null
+++ b/src/event_taxonomy/adapters/_severity.py
@@ -0,0 +1,85 @@
+"""Centralized severity mapping logic for all tool representations."""
+
+from event_taxonomy.schema import Severity
+
+# bus-factor / dep-risk / knowledge-silo style: CRITICAL/HIGH/MEDIUM/LOW(/OK)
+_LABEL_MAP: dict[str, Severity] = {
+    "CRITICAL": Severity.CRITICAL,
+    "HIGH": Severity.HIGH,
+    "MEDIUM": Severity.MEDIUM,
+    "LOW": Severity.LOW,
+    "OK": Severity.INFO,
+}
+
+
+def map_risk_label(label: str) -> Severity:
+    """Map CRITICAL/HIGH/MEDIUM/LOW/OK string labels."""
+    return _LABEL_MAP.get(label.upper(), Severity.INFO)
+
+
+# doc-drift style: error/warning/info
+_DOC_MAP: dict[str, Severity] = {
+    "error": Severity.HIGH,
+    "warning": Severity.MEDIUM,
+    "info": Severity.INFO,
+}
+
+
+def map_doc_severity(sev: str) -> Severity:
+    """Map error/warning/info string labels."""
+    return _DOC_MAP.get(sev.lower(), Severity.INFO)
+
+
+# perf-regression style: integer 1-10
+def map_int_severity(score: int) -> Severity:
+    """Map integer severity (1-10 scale)."""
+    if score >= 8:
+        return Severity.CRITICAL
+    if score >= 6:
+        return Severity.HIGH
+    if score >= 4:
+        return Severity.MEDIUM
+    if score >= 2:
+        return Severity.LOW
+    return Severity.INFO
+
+
+# schema-evolution style: safe/cautious/dangerous
+_SCHEMA_MAP: dict[str, Severity] = {
+    "dangerous": Severity.CRITICAL,
+    "cautious": Severity.MEDIUM,
+    "safe": Severity.LOW,
+}
+
+
+def map_schema_risk(level: str) -> Severity:
+    """Map safe/cautious/dangerous string labels."""
+    return _SCHEMA_MAP.get(level.lower(), Severity.INFO)
+
+
+# roadmap-entropy style: critical/high/moderate/low
+_ENTROPY_MAP: dict[str, Severity] = {
+    "critical": Severity.CRITICAL,
+    "high": Severity.HIGH,
+    "moderate": Severity.MEDIUM,
+    "low": Severity.LOW,
+}
+
+
+def map_entropy_risk(label: str) -> Severity:
+    """Map critical/high/moderate/low string labels."""
+    return _ENTROPY_MAP.get(label.lower(), Severity.INFO)
+
+
+# test-flakiness style: float 0.0-1.0
+def map_flakiness_rate(rate: float) -> Severity:
+    """Map flakiness rate (0.0-1.0) to severity."""
+    if rate >= 0.5:
+        return Severity.CRITICAL
+    if rate >= 0.3:
+        return Severity.HIGH
+    if rate >= 0.15:
+        return Severity.MEDIUM
+    if rate > 0.0:
+        return Severity.LOW
+    return Severity.INFO
diff --git a/src/event_taxonomy/adapters/bus_factor.py b/src/event_taxonomy/adapters/bus_factor.py
new file mode 100644
index 0000000..8de8dec
--- /dev/null
+++ b/src/event_taxonomy/adapters/bus_factor.py
@@ -0,0 +1,20 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_risk_label
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    return NormalizedFinding(
+        tool="bus-factor-analyzer",
+        category="bus-factor",
+        severity=map_risk_label(finding["risk_label"]),
+        message=f"Bus factor {finding['bus_factor']} — {finding['top_author']} owns {finding['top_author_pct']:.0f}%",
+        file=finding.get("file"),
+        metadata={
+            "top_author": finding["top_author"],
+            "top_author_pct": finding["top_author_pct"],
+            "num_contributors": finding["num_contributors"],
+            "bus_factor": finding["bus_factor"],
+        },
+    )
diff --git a/src/event_taxonomy/adapters/dep_risk.py b/src/event_taxonomy/adapters/dep_risk.py
new file mode 100644
index 0000000..8f02267
--- /dev/null
+++ b/src/event_taxonomy/adapters/dep_risk.py
@@ -0,0 +1,22 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_risk_label
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    label = finding.get("risk_label", "OK")
+    return NormalizedFinding(
+        tool="dep-risk-scanner",
+        category="dependency-risk",
+        severity=map_risk_label(label),
+        message=f"{finding['name']}@{finding['version']} — {label}",
+        recommendation=f"Vulnerability count: {finding.get('vuln_count', 0)}, months stale: {finding.get('months_stale', 0)}"
+        if finding.get("vuln_count") or finding.get("months_stale")
+        else None,
+        metadata={
+            k: finding[k]
+            for k in ("ecosystem", "vuln_score", "maintenance_score", "risk_score", "vulns")
+            if k in finding
+        },
+    )
diff --git a/src/event_taxonomy/adapters/doc_drift.py b/src/event_taxonomy/adapters/doc_drift.py
new file mode 100644
index 0000000..6fa6d58
--- /dev/null
+++ b/src/event_taxonomy/adapters/doc_drift.py
@@ -0,0 +1,16 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_doc_severity
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    return NormalizedFinding(
+        tool="doc-drift-detector",
+        category=finding.get("kind", "doc-drift"),
+        severity=map_doc_severity(finding["severity"]),
+        message=finding["message"],
+        file=finding.get("file"),
+        line=finding.get("lineno"),
+        metadata={"symbol": finding["symbol"]} if finding.get("symbol") else {},
+    )
diff --git a/src/event_taxonomy/adapters/knowledge_silo.py b/src/event_taxonomy/adapters/knowledge_silo.py
new file mode 100644
index 0000000..8b16ffc
--- /dev/null
+++ b/src/event_taxonomy/adapters/knowledge_silo.py
@@ -0,0 +1,24 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_risk_label
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    risk = finding.get("risk", "LOW")
+    if hasattr(risk, "value"):
+        risk = risk.value
+    return NormalizedFinding(
+        tool="knowledge-silo-detector",
+        category="knowledge-silo",
+        severity=map_risk_label(str(risk)),
+        message=f"{finding['filepath']} dominated by {finding['dominant_author']} ({finding['dominant_commits']}/{finding['total_commits']} commits)",
+        file=finding.get("filepath"),
+        metadata={
+            "dominant_author": finding["dominant_author"],
+            "dominance_ratio": finding["dominant_commits"] / finding["total_commits"]
+            if finding["total_commits"]
+            else 0,
+            "other_authors": finding.get("other_authors", {}),
+        },
+    )
diff --git a/src/event_taxonomy/adapters/perf_regression.py b/src/event_taxonomy/adapters/perf_regression.py
new file mode 100644
index 0000000..172d0a9
--- /dev/null
+++ b/src/event_taxonomy/adapters/perf_regression.py
@@ -0,0 +1,16 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_int_severity
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    return NormalizedFinding(
+        tool="perf-regression-spotter",
+        category=finding.get("pattern", "performance"),
+        severity=map_int_severity(finding["severity"]),
+        message=finding["message"],
+        file=finding.get("file"),
+        line=finding.get("line"),
+        metadata={"snippet": finding["snippet"]} if finding.get("snippet") else {},
+    )
diff --git a/src/event_taxonomy/adapters/roadmap_entropy.py b/src/event_taxonomy/adapters/roadmap_entropy.py
new file mode 100644
index 0000000..b1790b4
--- /dev/null
+++ b/src/event_taxonomy/adapters/roadmap_entropy.py
@@ -0,0 +1,26 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_entropy_risk
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    label = finding.get("risk_label", "low")
+    return NormalizedFinding(
+        tool="roadmap-entropy",
+        category="roadmap-entropy",
+        severity=map_entropy_risk(label),
+        message=f"Entropy score {finding['entropy_score']:.2f} — {label}",
+        metadata={
+            k: finding[k]
+            for k in (
+                "base_count",
+                "head_count",
+                "item_count_delta",
+                "description_churn",
+                "priority_shuffles",
+                "entropy_score",
+            )
+            if k in finding
+        },
+    )
diff --git a/src/event_taxonomy/adapters/schema_evolution.py b/src/event_taxonomy/adapters/schema_evolution.py
new file mode 100644
index 0000000..b8a58c4
--- /dev/null
+++ b/src/event_taxonomy/adapters/schema_evolution.py
@@ -0,0 +1,22 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_schema_risk
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    op = finding.get("operation", {})
+    if hasattr(op, "op_type"):
+        op_type = op.op_type
+        op_args = getattr(op, "args", [])
+    else:
+        op_type = op.get("op_type", "unknown")
+        op_args = op.get("args", [])
+    return NormalizedFinding(
+        tool="schema-evolution-advisor",
+        category=op_type,
+        severity=map_schema_risk(finding["risk_level"]),
+        message=finding["rationale"],
+        recommendation=finding.get("recommendation"),
+        metadata={"op_type": op_type, "args": op_args},
+    )
diff --git a/src/event_taxonomy/adapters/semantic_diff.py b/src/event_taxonomy/adapters/semantic_diff.py
new file mode 100644
index 0000000..e0d2786
--- /dev/null
+++ b/src/event_taxonomy/adapters/semantic_diff.py
@@ -0,0 +1,28 @@
+from typing import Any
+
+from event_taxonomy.schema import NormalizedFinding, Severity
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    cats = finding.get("categories", [])
+    added = finding.get("added", 0)
+    removed = finding.get("removed", 0)
+    churn = added + removed
+    if "DELETION" in cats or "DELETED_FILE" in cats:
+        severity = Severity.MEDIUM
+    elif churn > 100:
+        severity = Severity.HIGH
+    elif churn > 30:
+        severity = Severity.MEDIUM
+    elif churn > 0:
+        severity = Severity.LOW
+    else:
+        severity = Severity.INFO
+    return NormalizedFinding(
+        tool="semantic-diff",
+        category=",".join(cats) if cats else "change",
+        severity=severity,
+        message=finding.get("summary", f"Changed {finding['path']}"),
+        file=finding.get("path"),
+        metadata={"added": added, "removed": removed, "categories": cats},
+    )
diff --git a/src/event_taxonomy/adapters/test_flakiness.py b/src/event_taxonomy/adapters/test_flakiness.py
new file mode 100644
index 0000000..13bd647
--- /dev/null
+++ b/src/event_taxonomy/adapters/test_flakiness.py
@@ -0,0 +1,23 @@
+from typing import Any
+
+from event_taxonomy.adapters._severity import map_flakiness_rate
+from event_taxonomy.schema import NormalizedFinding
+
+
+def normalize(finding: dict[str, Any]) -> NormalizedFinding:
+    rate = finding["flakiness_rate"]
+    return NormalizedFinding(
+        tool="test-flakiness-analyzer",
+        category="flaky-test",
+        severity=map_flakiness_rate(rate),
+        message=f"{finding['test_id']} flaky at {rate:.0%} ({finding['fail_count']}/{finding['total_runs']} failures)",
+        metadata={
+            "test_id": finding["test_id"],
+            "classname": finding.get("classname", ""),
+            "total_runs": finding["total_runs"],
+            "pass_count": finding.get("pass_count", 0),
+            "fail_count": finding["fail_count"],
+            "flakiness_rate": rate,
+            "avg_duration": finding.get("avg_duration", 0),
+        },
+    )
diff --git a/src/event_taxonomy/registry.py b/src/event_taxonomy/registry.py
new file mode 100644
index 0000000..72dbf92
--- /dev/null
+++ b/src/event_taxonomy/registry.py
@@ -0,0 +1,48 @@
+"""Adapter registry — maps tool names to normalize functions."""
+
+from typing import Any, Callable
+
+from event_taxonomy.adapters import (
+    bus_factor,
+    dep_risk,
+    doc_drift,
+    knowledge_silo,
+    perf_regression,
+    roadmap_entropy,
+    schema_evolution,
+    semantic_diff,
+    test_flakiness,
+)
+from event_taxonomy.schema import NormalizedFinding, ToolEvent
+
+_ADAPTERS: dict[str, Callable[[dict[str, Any]], NormalizedFinding]] = {
+    "bus-factor-analyzer": bus_factor.normalize,
+    "dep-risk-scanner": dep_risk.normalize,
+    "doc-drift-detector": doc_drift.normalize,
+    "knowledge-silo-detector": knowledge_silo.normalize,
+    "perf-regression-spotter": perf_regression.normalize,
+    "roadmap-entropy": roadmap_entropy.normalize,
+    "schema-evolution-advisor": schema_evolution.normalize,
+    "semantic-diff": semantic_diff.normalize,
+    "test-flakiness-analyzer": test_flakiness.normalize,
+}
+
+
+def list_tools() -> list[str]:
+    return sorted(_ADAPTERS.keys())
+
+
+def get_adapter(tool_name: str) -> Callable[[dict[str, Any]], NormalizedFinding]:
+    if tool_name not in _ADAPTERS:
+        raise KeyError(f"Unknown tool: {tool_name}. Available: {', '.join(sorted(_ADAPTERS))}")
+    return _ADAPTERS[tool_name]
+
+
+def normalize_output(
+    tool_name: str,
+    raw_findings: list[dict[str, Any]],
+    tool_version: str = "unknown",
+) -> ToolEvent:
+    adapter = get_adapter(tool_name)
+    findings = [adapter(f) for f in raw_findings]
+    return ToolEvent(tool_name=tool_name, tool_version=tool_version, findings=findings)
diff --git a/src/event_taxonomy/schema.py b/src/event_taxonomy/schema.py
new file mode 100644
index 0000000..c7d88c0
--- /dev/null
+++ b/src/event_taxonomy/schema.py
@@ -0,0 +1,68 @@
+from __future__ import annotations
+
+import enum
+import json
+from dataclasses import asdict, dataclass, field
+from datetime import datetime, timezone
+from typing import Any
+
+
+class Severity(enum.IntEnum):
+    """Canonical severity levels, ordered from most to least severe."""
+
+    CRITICAL = 5
+    HIGH = 4
+    MEDIUM = 3
+    LOW = 2
+    INFO = 1
+
+    def __str__(self) -> str:
+        return self.name
+
+
+@dataclass
+class NormalizedFinding:
+    """Unified finding representation across all analysis tools."""
+
+    tool: str
+    category: str
+    severity: Severity
+    message: str
+    file: str | None = None
+    line: int | None = None
+    recommendation: str | None = None
+    metadata: dict[str, Any] = field(default_factory=dict)
+
+    def to_dict(self) -> dict[str, Any]:
+        d = asdict(self)
+        d["severity"] = self.severity.name
+        return d
+
+
+@dataclass
+class ToolEvent:
+    """Envelope wrapping a tool's normalized output."""
+
+    tool_name: str
+    tool_version: str
+    timestamp: str = field(default_factory=lambda: datetime.now(timezone.utc).isoformat())
+    findings: list[NormalizedFinding] = field(default_factory=list)
+
+    @property
+    def summary(self) -> dict[str, int]:
+        counts: dict[str, int] = {s.name: 0 for s in Severity}
+        for f in self.findings:
+            counts[f.severity.name] += 1
+        return {"total": len(self.findings), **counts}
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "tool_name": self.tool_name,
+            "tool_version": self.tool_version,
+            "timestamp": self.timestamp,
+            "findings": [f.to_dict() for f in self.findings],
+            "summary": self.summary,
+        }
+
+    def to_json(self, **kwargs: Any) -> str:
+        return json.dumps(self.to_dict(), **kwargs)
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diff --git a/tests/test_adapters.py b/tests/test_adapters.py
new file mode 100644
index 0000000..a57b575
--- /dev/null
+++ b/tests/test_adapters.py
@@ -0,0 +1,145 @@
+from event_taxonomy.adapters import (
+    bus_factor,
+    dep_risk,
+    doc_drift,
+    knowledge_silo,
+    perf_regression,
+    roadmap_entropy,
+    schema_evolution,
+    semantic_diff,
+    test_flakiness,
+)
+from event_taxonomy.schema import Severity
+
+
+def test_bus_factor():
+    f = bus_factor.normalize({
+        "file": "core.py",
+        "top_author": "alice",
+        "top_author_pct": 85.0,
+        "num_contributors": 2,
+        "bus_factor": 1,
+        "risk_label": "CRITICAL",
+    })
+    assert f.severity == Severity.CRITICAL
+    assert f.file == "core.py"
+    assert "alice" in f.message
+
+
+def test_dep_risk():
+    f = dep_risk.normalize({
+        "name": "requests",
+        "ecosystem": "pypi",
+        "version": "2.28.0",
+        "risk_label": "HIGH",
+        "vuln_count": 2,
+        "months_stale": 6,
+    })
+    assert f.severity == Severity.HIGH
+    assert "requests" in f.message
+
+
+def test_doc_drift():
+    f = doc_drift.normalize({
+        "kind": "docstring_param",
+        "severity": "error",
+        "message": "Param x not in signature",
+        "file": "model.py",
+        "lineno": 42,
+        "symbol": "process",
+    })
+    assert f.severity == Severity.HIGH
+    assert f.line == 42
+    assert f.file == "model.py"
+
+
+def test_knowledge_silo():
+    f = knowledge_silo.normalize({
+        "filepath": "auth.py",
+        "total_commits": 50,
+        "dominant_author": "bob",
+        "dominant_commits": 45,
+        "other_authors": {"alice": 5},
+        "risk": "HIGH",
+    })
+    assert f.severity == Severity.HIGH
+    assert "bob" in f.message
+
+
+def test_perf_regression():
+    f = perf_regression.normalize({
+        "pattern": "n-plus-one-query",
+        "severity": 8,
+        "file": "api.py",
+        "line": 123,
+        "message": "DB call inside loop",
+        "snippet": "for x in items: db.query(x)",
+    })
+    assert f.severity == Severity.CRITICAL
+    assert f.file == "api.py"
+    assert f.line == 123
+
+
+def test_roadmap_entropy():
+    f = roadmap_entropy.normalize({
+        "entropy_score": 0.65,
+        "risk_label": "high",
+        "base_count": 10,
+        "head_count": 15,
+        "item_count_delta": 5,
+        "description_churn": 0.25,
+        "priority_shuffles": 3,
+    })
+    assert f.severity == Severity.HIGH
+    assert "0.65" in f.message
+
+
+def test_schema_evolution():
+    f = schema_evolution.normalize({
+        "operation": {"op_type": "drop_column", "args": ["users", "password"]},
+        "risk_level": "dangerous",
+        "rationale": "Dropping column causes data loss",
+        "recommendation": "Back up first",
+    })
+    assert f.severity == Severity.CRITICAL
+    assert f.recommendation == "Back up first"
+
+
+def test_semantic_diff():
+    f = semantic_diff.normalize({
+        "path": "api.py",
+        "categories": ["REFACTOR", "FEATURE"],
+        "summary": "Modified api.py",
+        "added": 45,
+        "removed": 23,
+    })
+    assert f.severity == Severity.MEDIUM
+    assert f.file == "api.py"
+
+
+def test_semantic_diff_large_churn():
+    f = semantic_diff.normalize({
+        "path": "big.py",
+        "categories": ["FEATURE"],
+        "summary": "Rewrote big.py",
+        "added": 200,
+        "removed": 50,
+    })
+    assert f.severity == Severity.HIGH
+
+
+def test_test_flakiness():
+    f = test_flakiness.normalize({
+        "test_id": "tests.integration::test_auth",
+        "classname": "tests.integration",
+        "total_runs": 20,
+        "pass_count": 12,
+        "fail_count": 8,
+        "error_count": 0,
+        "skip_count": 0,
+        "flakiness_rate": 0.4,
+        "avg_duration": 1.25,
+        "duration_stddev": 0.35,
+    })
+    assert f.severity == Severity.HIGH
+    assert "40%" in f.message
diff --git a/tests/test_schema.py b/tests/test_schema.py
new file mode 100644
index 0000000..03b1211
--- /dev/null
+++ b/tests/test_schema.py
@@ -0,0 +1,52 @@
+import json
+
+from event_taxonomy.schema import NormalizedFinding, Severity, ToolEvent
+
+
+def test_severity_ordering():
+    assert Severity.CRITICAL > Severity.HIGH > Severity.MEDIUM > Severity.LOW > Severity.INFO
+
+
+def test_severity_str():
+    assert str(Severity.CRITICAL) == "CRITICAL"
+    assert str(Severity.INFO) == "INFO"
+
+
+def test_finding_construction():
+    f = NormalizedFinding(
+        tool="test-tool",
+        category="test",
+        severity=Severity.HIGH,
+        message="something broke",
+        file="foo.py",
+        line=42,
+    )
+    assert f.tool == "test-tool"
+    assert f.severity == Severity.HIGH
+    assert f.file == "foo.py"
+    assert f.line == 42
+    assert f.metadata == {}
+    assert f.recommendation is None
+
+
+def test_finding_to_dict():
+    f = NormalizedFinding(tool="t", category="c", severity=Severity.LOW, message="m")
+    d = f.to_dict()
+    assert d["severity"] == "LOW"
+    assert d["tool"] == "t"
+
+
+def test_tool_event_serialization():
+    findings = [
+        NormalizedFinding(tool="t", category="c", severity=Severity.HIGH, message="a"),
+        NormalizedFinding(tool="t", category="c", severity=Severity.LOW, message="b"),
+    ]
+    event = ToolEvent(tool_name="t", tool_version="1.0", findings=findings)
+    d = event.to_dict()
+    assert d["summary"]["total"] == 2
+    assert d["summary"]["HIGH"] == 1
+    assert d["summary"]["LOW"] == 1
+    j = event.to_json()
+    parsed = json.loads(j)
+    assert parsed["tool_name"] == "t"
+    assert len(parsed["findings"]) == 2
diff --git a/tests/test_severity.py b/tests/test_severity.py
new file mode 100644
index 0000000..50af96f
--- /dev/null
+++ b/tests/test_severity.py
@@ -0,0 +1,60 @@
+from event_taxonomy.adapters._severity import (
+    map_doc_severity,
+    map_entropy_risk,
+    map_flakiness_rate,
+    map_int_severity,
+    map_risk_label,
+    map_schema_risk,
+)
+from event_taxonomy.schema import Severity
+
+
+def test_risk_label_mapping():
+    assert map_risk_label("CRITICAL") == Severity.CRITICAL
+    assert map_risk_label("high") == Severity.HIGH
+    assert map_risk_label("Medium") == Severity.MEDIUM
+    assert map_risk_label("LOW") == Severity.LOW
+    assert map_risk_label("OK") == Severity.INFO
+    assert map_risk_label("unknown") == Severity.INFO
+
+
+def test_doc_severity_mapping():
+    assert map_doc_severity("error") == Severity.HIGH
+    assert map_doc_severity("warning") == Severity.MEDIUM
+    assert map_doc_severity("info") == Severity.INFO
+    assert map_doc_severity("ERROR") == Severity.HIGH
+
+
+def test_int_severity_boundaries():
+    assert map_int_severity(10) == Severity.CRITICAL
+    assert map_int_severity(8) == Severity.CRITICAL
+    assert map_int_severity(7) == Severity.HIGH
+    assert map_int_severity(6) == Severity.HIGH
+    assert map_int_severity(5) == Severity.MEDIUM
+    assert map_int_severity(4) == Severity.MEDIUM
+    assert map_int_severity(3) == Severity.LOW
+    assert map_int_severity(2) == Severity.LOW
+    assert map_int_severity(1) == Severity.INFO
+
+
+def test_schema_risk_mapping():
+    assert map_schema_risk("dangerous") == Severity.CRITICAL
+    assert map_schema_risk("cautious") == Severity.MEDIUM
+    assert map_schema_risk("safe") == Severity.LOW
+    assert map_schema_risk("Dangerous") == Severity.CRITICAL
+
+
+def test_entropy_risk_mapping():
+    assert map_entropy_risk("critical") == Severity.CRITICAL
+    assert map_entropy_risk("high") == Severity.HIGH
+    assert map_entropy_risk("moderate") == Severity.MEDIUM
+    assert map_entropy_risk("low") == Severity.LOW
+
+
+def test_flakiness_rate_boundaries():
+    assert map_flakiness_rate(0.0) == Severity.INFO
+    assert map_flakiness_rate(0.05) == Severity.LOW
+    assert map_flakiness_rate(0.15) == Severity.MEDIUM
+    assert map_flakiness_rate(0.3) == Severity.HIGH
+    assert map_flakiness_rate(0.5) == Severity.CRITICAL
+    assert map_flakiness_rate(1.0) == Severity.CRITICAL