feat(verification): add evidence ladder verifier

.kiro/specs/openrouter-sast-harness/tasks.md

@@ -9,7 +9,7 @@ Checklist completion is not product completion. Each phase now carries a functio
 - `integrated`: the feature participates in the harness runtime, traces, evidence, and reports.
 - `production`: the feature is robust for real repositories, CI budgets, and analyst audit.
 
-Current verified gate: `scaffold_quick_scan`.
+Current verified gate: `usable_harness_mvp` partial.
 
 Do not report OpenUltraSAST as a working security harness until `usable_harness_mvp` is checked.
 
@@ -77,7 +77,7 @@ Do not report OpenUltraSAST as a working security harness until `usable_harness_
 - [x] Quick scan is uv-managed and covered by unit tests.
 - [ ] Quick scan includes real LLM hunter execution. This is intentionally deferred to standard mode.
 - [ ] Quick scan includes SARIF output. This is intentionally deferred to Phase 9.
-- [ ] Quick scan includes enforced verifier decisions. This is intentionally deferred to Phase 6.
+- [x] Quick scan includes enforced verifier decisions.
 
 ## Gate: `usable_harness_mvp`
 
@@ -85,10 +85,10 @@ Do not report OpenUltraSAST as a working security harness until `usable_harness_
 - [x] Event traces are emitted for every scan stage.
 - [x] Static mapping ingestion feeds FileTarget hints and verifier evidence candidates.
 - [x] Entry-point reachability feeds FileTarget reachability hints and ranking priority.
-- [ ] Evidence ladder state machine prevents invalid verified statuses.
+- [x] Evidence ladder state machine prevents invalid verified statuses.
-- [ ] Independent verifier runs on fixture findings without hunter reasoning.
+- [x] Independent verifier runs on fixture findings without hunter reasoning.
 - [ ] JSON, Markdown, SARIF, and manifest artifacts share finding IDs and evidence references.
-- [ ] A fixture scan demonstrates one accepted static-corroborated finding and one rejected false positive.
+- [x] A fixture scan demonstrates one accepted static-corroborated finding and one rejected false positive.
 
 ## Phase 5: Harness Runtime (`usable_harness_mvp` prerequisite)
 
@@ -117,12 +117,12 @@ Do not report OpenUltraSAST as a working security harness until `usable_harness_
 
 ## Phase 6: Verification (`usable_harness_mvp` prerequisite)
 
-- [ ] Define evidence ladder state machine.
+- [x] Define evidence ladder state machine.
-- [ ] Implement independent verifier prompt and schema.
+- [x] Implement independent verifier prompt and schema.
-- [ ] Ensure verifier context excludes hunter reasoning.
+- [x] Ensure verifier context excludes hunter reasoning.
-- [ ] Implement pro-case, counter-case, tie-breaker, and required-next-step fields.
+- [x] Implement pro-case, counter-case, tie-breaker, and required-next-step fields.
-- [ ] Enforce that verified report status requires at least `static_corroboration`.
+- [x] Enforce that verified report status requires at least `static_corroboration`.
-- [ ] Add tests for invalid evidence transitions.
+- [x] Add tests for invalid evidence transitions.
 
 ## Gate: `standard_security_harness`
 

src/openultrasast/cli.py

@@ -13,6 +13,7 @@ from .preprocess import preprocess_repository, write_preprocess_artifact
 from .rank import rank_targets, write_rankings
 from .reports import write_markdown_report
 from .run import create_scan_run
+from .verification import verify_findings, write_verification_results
 
 
 def main(argv: list[str] | None = None) -> int:
@@ -66,6 +67,8 @@ def _scan(path: Path, config_path: Path, mode: str) -> int:
     write_rankings(rankings, run.root / "rank" / "ranking.json")
     findings = runtime.run_stage("quick_findings", lambda: quick_scan_findings(run.target, targets, rankings))
     write_findings(findings, run.root / "findings.json")
+    verifications = runtime.run_stage("verify", lambda: verify_findings(findings))
+    write_verification_results(verifications, run.root / "verification.json")
     runtime.run_stage("report", lambda: write_markdown_report(findings, run.root / "report.md"))
     runtime.finish(status="succeeded")
     print(f"scan_id={run.scan_id}")

src/openultrasast/verification.py

@@ -0,0 +1,131 @@
+from __future__ import annotations
+
+import json
+from dataclasses import asdict, dataclass
+from enum import StrEnum
+from pathlib import Path
+
+from .findings import StaticFinding
+
+
+class EvidenceLevel(StrEnum):
+    SUSPICION = "suspicion"
+    STATIC_CORROBORATION = "static_corroboration"
+    CRASH_REPRODUCED = "crash_reproduced"
+    ROOT_CAUSE_EXPLAINED = "root_cause_explained"
+    EXPLOIT_DEMONSTRATED = "exploit_demonstrated"
+    PATCH_VALIDATED = "patch_validated"
+
+
+class VerificationStatus(StrEnum):
+    ACCEPTED = "accepted"
+    REJECTED = "rejected"
+    NEEDS_EVIDENCE = "needs_evidence"
+
+
+@dataclass(frozen=True)
+class VerificationResult:
+    finding_id: str
+    status: VerificationStatus
+    evidence_level: EvidenceLevel
+    verified: bool
+    pro_case: str
+    counter_case: str
+    tie_breaker: str
+    required_next_step: str
+    context_sources: list[str]
+
+
+def validate_evidence_transition(current: EvidenceLevel | str, target: EvidenceLevel | str) -> EvidenceLevel:
+    current_level = EvidenceLevel(current)
+    target_level = EvidenceLevel(target)
+    if _EVIDENCE_ORDER[target_level] < _EVIDENCE_ORDER[current_level]:
+        raise ValueError(f"cannot move evidence level backward: {current_level} -> {target_level}")
+    if _EVIDENCE_ORDER[target_level] - _EVIDENCE_ORDER[current_level] > 1:
+        raise ValueError(f"cannot skip evidence levels: {current_level} -> {target_level}")
+    return target_level
+
+
+def is_report_verified(evidence_level: EvidenceLevel | str, status: VerificationStatus | str) -> bool:
+    level = EvidenceLevel(evidence_level)
+    verification_status = VerificationStatus(status)
+    return verification_status == VerificationStatus.ACCEPTED and _EVIDENCE_ORDER[level] >= _EVIDENCE_ORDER[EvidenceLevel.STATIC_CORROBORATION]
+
+
+def build_independent_verifier_context(finding: StaticFinding) -> dict[str, object]:
+    return {
+        "finding_id": finding.finding_id,
+        "path": finding.path,
+        "line": finding.line,
+        "function_name": finding.function_name,
+        "title": finding.title,
+        "severity": finding.severity,
+        "evidence_level": finding.evidence_level,
+        "reachability_status": finding.reachability_status,
+        "reachability_evidence": finding.reachability_evidence,
+        "reachability_conditions": finding.reachability_conditions,
+        "tags": finding.tags,
+    }
+
+
+def verify_finding(finding: StaticFinding) -> VerificationResult:
+    level = EvidenceLevel(finding.evidence_level)
+    context = build_independent_verifier_context(finding)
+    context_sources = sorted(context.keys())
+
+    if _EVIDENCE_ORDER[level] < _EVIDENCE_ORDER[EvidenceLevel.STATIC_CORROBORATION]:
+        return VerificationResult(
+            finding_id=finding.finding_id,
+            status=VerificationStatus.NEEDS_EVIDENCE,
+            evidence_level=level,
+            verified=False,
+            pro_case="A candidate issue exists, but it has not reached static corroboration.",
+            counter_case="The current evidence can still be a model or heuristic suspicion.",
+            tie_breaker="Add static analyzer, source, or runtime evidence that corroborates the claim.",
+            required_next_step="Collect static corroboration before reporting as verified.",
+            context_sources=context_sources,
+        )
+
+    if finding.reachability_status == "unknown":
+        return VerificationResult(
+            finding_id=finding.finding_id,
+            status=VerificationStatus.REJECTED,
+            evidence_level=level,
+            verified=False,
+            pro_case="A static pattern matched the source line.",
+            counter_case="No function-level attacker-reachable entry point currently reaches this line.",
+            tie_breaker="Provide call-graph, route, CLI, parser, or dynamic evidence linking attacker input to this function.",
+            required_next_step="Add reachability evidence before prioritizing a fix.",
+            context_sources=context_sources,
+        )
+
+    return VerificationResult(
+        finding_id=finding.finding_id,
+        status=VerificationStatus.ACCEPTED,
+        evidence_level=level,
+        verified=is_report_verified(level, VerificationStatus.ACCEPTED),
+        pro_case="Static corroboration exists and function-level reachability evidence is attached.",
+        counter_case="Impact and exploitability still require deeper verifier or dynamic evidence.",
+        tie_breaker="Confirm attacker control, sanitizer absence, and impact in the next verification depth.",
+        required_next_step="Proceed to standard verifier or dynamic reproduction if severity warrants it.",
+        context_sources=context_sources,
+    )
+
+
+def verify_findings(findings: list[StaticFinding]) -> list[VerificationResult]:
+    return [verify_finding(finding) for finding in findings]
+
+
+def write_verification_results(results: list[VerificationResult], path: Path) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(json.dumps({"verifications": [asdict(result) for result in results]}, indent=2, sort_keys=True) + "\n")
+
+
+_EVIDENCE_ORDER = {
+    EvidenceLevel.SUSPICION: 0,
+    EvidenceLevel.STATIC_CORROBORATION: 1,
+    EvidenceLevel.CRASH_REPRODUCED: 2,
+    EvidenceLevel.ROOT_CAUSE_EXPLAINED: 3,
+    EvidenceLevel.EXPLOIT_DEMONSTRATED: 4,
+    EvidenceLevel.PATCH_VALIDATED: 5,
+}

tests/test_verification.py

@@ -0,0 +1,141 @@
+import json
+from pathlib import Path
+
+import pytest
+
+from openultrasast.cli import main
+from openultrasast.findings import StaticFinding
+from openultrasast.verification import (
+    EvidenceLevel,
+    VerificationStatus,
+    build_independent_verifier_context,
+    is_report_verified,
+    validate_evidence_transition,
+    verify_finding,
+    write_verification_results,
+)
+
+
+def test_evidence_transition_rejects_backward_and_skipped_levels() -> None:
+    assert validate_evidence_transition("suspicion", "static_corroboration") == EvidenceLevel.STATIC_CORROBORATION
+
+    with pytest.raises(ValueError, match="backward"):
+        validate_evidence_transition("root_cause_explained", "static_corroboration")
+
+    with pytest.raises(ValueError, match="skip"):
+        validate_evidence_transition("suspicion", "root_cause_explained")
+
+
+def test_verified_status_requires_static_corroboration_and_acceptance() -> None:
+    assert is_report_verified(EvidenceLevel.STATIC_CORROBORATION, VerificationStatus.ACCEPTED)
+    assert not is_report_verified(EvidenceLevel.SUSPICION, VerificationStatus.ACCEPTED)
+    assert not is_report_verified(EvidenceLevel.STATIC_CORROBORATION, VerificationStatus.REJECTED)
+
+
+def test_independent_verifier_context_excludes_hunter_reasoning() -> None:
+    finding = _finding(evidence_level="static_corroboration", reachability_status="reachable")
+
+    context = build_independent_verifier_context(finding)
+
+    assert "hunter_reasoning" not in context
+    assert "chain_of_thought" not in context
+    assert context["finding_id"] == finding.finding_id
+    assert context["reachability_status"] == "reachable"
+
+
+def test_verifier_accepts_reachable_static_corroborated_finding() -> None:
+    finding = _finding(evidence_level="static_corroboration", reachability_status="reachable")
+
+    result = verify_finding(finding)
+
+    assert result.status == VerificationStatus.ACCEPTED
+    assert result.verified
+    assert result.evidence_level == EvidenceLevel.STATIC_CORROBORATION
+    assert result.pro_case
+    assert result.counter_case
+    assert result.tie_breaker
+    assert result.required_next_step
+
+
+def test_verifier_rejects_unknown_reachability_static_finding() -> None:
+    finding = _finding(evidence_level="static_corroboration", reachability_status="unknown")
+
+    result = verify_finding(finding)
+
+    assert result.status == VerificationStatus.REJECTED
+    assert not result.verified
+    assert "reach" in result.counter_case.lower()
+    assert "call-graph" in result.tie_breaker
+
+
+def test_verifier_does_not_verify_suspicion_only_finding() -> None:
+    finding = _finding(evidence_level="suspicion", reachability_status="reachable")
+
+    result = verify_finding(finding)
+
+    assert result.status == VerificationStatus.NEEDS_EVIDENCE
+    assert not result.verified
+    assert result.required_next_step == "Collect static corroboration before reporting as verified."
+
+
+def test_write_verification_results_artifact(tmp_path: Path) -> None:
+    result = verify_finding(_finding(evidence_level="static_corroboration", reachability_status="reachable"))
+    output = tmp_path / "verification.json"
+
+    write_verification_results([result], output)
+
+    payload = json.loads(output.read_text())
+    assert payload["verifications"][0]["finding_id"] == "python-unsafe-eval:app.py:3"
+    assert payload["verifications"][0]["status"] == "accepted"
+
+
+def test_cli_scan_writes_accepted_and_rejected_verifications(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    (repo / "app.py").write_text(
+        "@app.route('/admin')\n"
+        "def admin():\n"
+        "    return eval(request.data)\n"
+        "\n"
+        "def helper(value):\n"
+        "    return exec(value)\n"
+    )
+    monkeypatch.setenv("OPENULTRASAST_RUNS_DIR", ".runs")
+
+    assert main(["scan", str(repo), "--mode", "quick"]) == 0
+
+    run_dirs = sorted((repo / ".runs").iterdir())
+    verification_path = run_dirs[-1] / "verification.json"
+    payload = json.loads(verification_path.read_text())
+    statuses = {item["status"] for item in payload["verifications"]}
+
+    assert statuses == {"accepted", "rejected"}
+
+
+def _finding(*, evidence_level: str, reachability_status: str) -> StaticFinding:
+    evidence = [
+        {
+            "kind": "route",
+            "access_level": "public",
+            "line": 1,
+            "end_line": 3,
+            "function_name": "admin",
+            "conditions": [],
+        }
+    ] if reachability_status == "reachable" else []
+    return StaticFinding(
+        finding_id="python-unsafe-eval:app.py:3",
+        path="app.py",
+        title="Dynamic Python execution needs review",
+        severity="high",
+        confidence="medium",
+        evidence_level=evidence_level,
+        rationale="Static pattern matched.",
+        line=3,
+        function_name="admin" if reachability_status == "reachable" else None,
+        reachability_status=reachability_status,
+        reachability_evidence=evidence,
+        reachability_conditions=[],
+        tags=["syscall_entry"],
+        ranking_priority=3.0,
+    )