feat(audit): dead-code deletion_safety cross-check (closes #238)

scripts/commands/audit.py

@@ -110,6 +110,13 @@
                         help="perf-hint: single category filter")
     parser.add_argument("--no-confirm-hash", action="store_true", default=False,
                         help="staleness: skip content-hash confirmation")
+    parser.add_argument("--no-verify-impact", dest="verify_impact",
+                        action="store_false", default=True,
+                        help="dead-code: skip per-finding deletion_safety cross-check "
+                             "against impact analysis (issue #238)")
+    parser.add_argument("--verify-impact-limit", type=int, default=None,
+                        help="dead-code: max findings to cross-check with impact "
+                             "analysis (default: 20)")
 
 
 def _parse_checks(check_arg: str) -> List[str]:
@@ -127,7 +134,7 @@
     return parts or list(ALL_CHECKS)
 
 
 def _build_namespace(base_args, check_name: str) -> argparse.Namespace:
     ns = argparse.Namespace()
     for attr in ("format", "top", "max_tokens", "lite", "deep", "db_path",
                  "diff_base", "diff_scope", "disable_suppression",
@@ -138,6 +145,8 @@
         ns.categories = getattr(base_args, "categories", None)
         ns.max_files = getattr(base_args, "max_files", None) or 3000
         ns.max_results = getattr(base_args, "max_results", None) or 100
+        ns.verify_impact = getattr(base_args, "verify_impact", True)
+        ns.verify_impact_limit = getattr(base_args, "verify_impact_limit", None) or 20
     elif check_name == "complexity":
         ns.name = getattr(base_args, "name", None)
         ns.file = getattr(base_args, "file", None)

scripts/commands/dead_code.py

@@ -13,6 +13,15 @@ def add_args(parser):
                         help="Max files to scan (default: 3000)")
     parser.add_argument("--max-results", type=int, default=100,
                         help="Max results per category (default: 100)")
+    parser.add_argument("--no-verify-impact", dest="verify_impact",
+                        action="store_false", default=True,
+                        help="Skip per-finding deletion_safety cross-check against "
+                             "impact analysis (issue #238). On by default; disable "
+                             "on very large result sets if it's too slow.")
+    parser.add_argument("--verify-impact-limit", type=int, default=20,
+                        help="Max number of findings to cross-check with impact "
+                             "analysis per run (default: 20, highest-confidence "
+                             "findings first)")
 
 
 def execute(args, workspace):
@@ -82,6 +91,47 @@ def execute(args, workspace):
                 if "stats" not in result:
                     result["stats"] = {}
                 result["stats"]["confidence_distribution"] = dist
+
+        # Issue #238: per-finding deletion_safety cross-check.
+        #
+        # "status: dead" in the registry only means "no CALLS edge found" — it
+        # does NOT mean safe to delete (entry points like HTTP handlers, CLI
+        # subcommands, and exported APIs routinely have zero inbound edges but
+        # are still critical). Previously an agent had to manually chain
+        # `audit --check dead-code` -> `context --check trace --direction up`
+        # to verify this per finding; analyze_impact() already computes exactly
+        # this signal for the "delete" action, it just wasn't wired in here.
+        if getattr(args, "verify_impact", True):
+            try:
+                from impact_engine import analyze_impact
+                all_items = []
+                for cat_items in result.get("results", {}).values():
+                    if isinstance(cat_items, list):
+                        all_items.extend(cat_items)
+                limit = max(0, getattr(args, "verify_impact_limit", 20) or 0)
+                _risk_to_safety = {
+                    "low": "safe",
+                    "medium": "caution",
+                    "high": "entry_point_likely",
+                    "critical": "entry_point_likely",
+                }
+                for item in all_items[:limit]:
+                    if not isinstance(item, dict):
+                        continue
+                    name = item.get("name")
+                    if not name:
+                        continue
+                    try:
+                        impact_result = analyze_impact(
+                            name, workspace, action="delete", depth=3
+                        )
+                        risk = impact_result.get("risk", "low")
+                        item["deletion_safety"] = _risk_to_safety.get(risk, "caution")
+                        item["deletion_impact_stats"] = impact_result.get("stats")
+                    except Exception:
+                        item["deletion_safety"] = "unknown"
+            except ImportError:
+                pass
     return result
 
 # Issue #199: deprecated "dead-code" alias registration removed; this module is now an implementation module imported by the "audit" umbrella command.

tests/test_dead_code_command.py

@@ -0,0 +1,126 @@
+"""Tests for the dead-code command's deletion_safety cross-check (issue #238).
+
+`audit --check dead-code` previously reported `status: dead` from the
+registry with no signal about whether a finding is actually safe to delete
+— an agent had to manually chain a separate `context --check trace
+--direction up` call per finding to check for entry points. This wires
+`impact_engine.analyze_impact(action="delete")` (which already computes
+exactly this signal) directly into the dead-code command output.
+"""
+
+import argparse
+import os
+import sys
+from unittest import mock
+
+import pytest
+
+SCRIPT_DIR = os.path.join(
+    os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "scripts"
+)
+if SCRIPT_DIR not in sys.path:
+    sys.path.insert(0, SCRIPT_DIR)
+
+from commands import dead_code  # noqa: E402
+
+
+def _base_args(**overrides):
+    ns = argparse.Namespace(
+        workspace=".",
+        categories=None,
+        max_files=3000,
+        max_results=100,
+        verify_impact=True,
+        verify_impact_limit=20,
+    )
+    for k, v in overrides.items():
+        setattr(ns, k, v)
+    return ns
+
+
+def _fake_dead_code_result():
+    return {
+        "status": "ok",
+        "stats": {"total_dead_code": 2},
+        "results": {
+            "unused_exports": [
+                {"file": "AdGate.tsx", "line": 39, "name": "AdGate", "type": "default_export"},
+            ],
+            "registry_dead": [
+                {"file": "utils.ts", "line": 10, "name": "reallyUnusedHelper", "type": "function"},
+            ],
+        },
+    }
+
+
+class TestDeletionSafetyCrossCheck:
+    def test_high_risk_symbol_flagged_entry_point_likely(self):
+        """A dead-code finding that analyze_impact reports as high-risk
+        (real dependents exist) must not be silently labeled safe."""
+        with mock.patch("commands.dead_code.detect_dead_code", return_value=_fake_dead_code_result()), \
+             mock.patch("hybrid_engine.create_hybrid_engine", side_effect=ImportError), \
+             mock.patch(
+                "impact_engine.analyze_impact",
+                side_effect=lambda name, ws, **kw: {
+                    "risk": "high" if name == "AdGate" else "low",
+                    "stats": {"direct_dependents": 6 if name == "AdGate" else 0},
+                },
+            ):
+            result = dead_code.execute(_base_args(), ".")
+
+        items_by_name = {
+            item["name"]: item
+            for cat in result["results"].values()
+            for item in cat
+        }
+        assert items_by_name["AdGate"]["deletion_safety"] == "entry_point_likely"
+        assert items_by_name["reallyUnusedHelper"]["deletion_safety"] == "safe"
+
+    def test_no_verify_impact_flag_skips_cross_check(self):
+        """--no-verify-impact must not call analyze_impact at all."""
+        with mock.patch("commands.dead_code.detect_dead_code", return_value=_fake_dead_code_result()), \
+             mock.patch("hybrid_engine.create_hybrid_engine", side_effect=ImportError), \
+             mock.patch("impact_engine.analyze_impact") as mock_analyze:
+            result = dead_code.execute(_base_args(verify_impact=False), ".")
+
+        mock_analyze.assert_not_called()
+        for cat in result["results"].values():
+            for item in cat:
+                assert "deletion_safety" not in item
+
+    def test_verify_impact_limit_caps_calls(self):
+        """Only the first N findings (across all categories combined) are
+        cross-checked, to bound cost on large dead-code result sets."""
+        many_findings = {
+            "status": "ok",
+            "stats": {"total_dead_code": 10},
+            "results": {
+                "unused_exports": [
+                    {"file": f"f{i}.ts", "line": i, "name": f"fn{i}", "type": "function"}
+                    for i in range(10)
+                ],
+            },
+        }
+        with mock.patch("commands.dead_code.detect_dead_code", return_value=many_findings), \
+             mock.patch("hybrid_engine.create_hybrid_engine", side_effect=ImportError), \
+             mock.patch(
+                "impact_engine.analyze_impact",
+                return_value={"risk": "low", "stats": {}},
+            ) as mock_analyze:
+            dead_code.execute(_base_args(verify_impact_limit=3), ".")
+
+        assert mock_analyze.call_count == 3
+
+    def test_analyze_impact_failure_does_not_crash_command(self):
+        """If analyze_impact raises for a given symbol, the command must
+        still return successfully with an 'unknown' safety label — not
+        propagate the exception and break the whole dead-code report."""
+        with mock.patch("commands.dead_code.detect_dead_code", return_value=_fake_dead_code_result()), \
+             mock.patch("hybrid_engine.create_hybrid_engine", side_effect=ImportError), \
+             mock.patch("impact_engine.analyze_impact", side_effect=RuntimeError("boom")):
+            result = dead_code.execute(_base_args(), ".")
+
+        assert result["status"] == "ok"
+        for cat in result["results"].values():
+            for item in cat:
+                assert item["deletion_safety"] == "unknown"