feat: evidence gate — verify citations and fake-green tripwires (#4)

.github/workflows/validate.yml

@@ -14,3 +14,5 @@ jobs:
         run: node scripts/validate-plugin.cjs
       - name: Check frontmatter token budgets
         run: node scripts/token-report.cjs --check
+      - name: Test the evidence gate
+        run: node scripts/test-verify-evidence.cjs

AGENTS.md

@@ -12,7 +12,9 @@ docs website (`website/`, Astro Starlight). The only repo-level check is
 - Plugin: nothing to build. Lint before committing: `node scripts/validate-plugin.cjs`
   — validates every SKILL.md against the 8-section anatomy and plugin/marketplace
   version sync; `node scripts/token-report.cjs --check` — enforces token budgets
-  on skill/agent frontmatter (both run in CI, `.github/workflows/validate.yml`).
+  on skill/agent frontmatter; `node scripts/test-verify-evidence.cjs` — exercises
+  the evidence gate (`scripts/verify-evidence.cjs`: citation resolution +
+  fake-green tripwires). All three run in CI, `.github/workflows/validate.yml`.
 - Test by installing locally:
   `/plugin marketplace add <path-or-repo>` → `/plugin install claudekit` → `/claudekit:init`
 - Website (`cd website/`): `npm install`, `npm run dev`, `npm run build`,

CHANGELOG.md

@@ -24,6 +24,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   skill/agent frontmatter with named budgets, enforced in CI via `--check` (#2)
 - CI workflow `.github/workflows/validate.yml` running the anatomy and
   token-budget checks on pushes to `main` and PRs (#1, #2)
+- `scripts/verify-evidence.cjs` — evidence gate that mechanically checks an
+  agent's claimed evidence: resolves `file:line` citations against real
+  paths/ranges (`--citations`) and scans `git diff HEAD` for fake-green
+  tampering — deleted test files, added test skips, new TODO/FIXME
+  (`--tripwires`); loud gate (exit 1 violations, 2 usage/crash). Deliberately
+  does not attempt deep test-tamper analysis
+- `scripts/verify-evidence-hook.cjs` — fail-open Stop/PostToolUse wrapper that
+  surfaces tripwire findings as advisory, never blocking
+- `scripts/test-verify-evidence.cjs` — zero-dependency fixture runner for the
+  evidence gate (26 cases), added to CI
 
 ## [4.0.0] - 2026-05-07
 

README.md

@@ -161,15 +161,22 @@ In practice, devs skip steps for trivial work. The chains show the full discipli
 ## Development
 
 CI (`.github/workflows/validate.yml`) lints every skill against the 8-section
-anatomy above, checks `plugin.json`/`marketplace.json` version sync, and
-enforces token budgets on the always-loaded skill/agent frontmatter (the
-"no agent-bloat" claim, measured). Run locally before committing:
+anatomy above, checks `plugin.json`/`marketplace.json` version sync, enforces
+token budgets on the always-loaded skill/agent frontmatter (the "no agent-bloat"
+claim, measured), and exercises the evidence gate. Run locally before committing:
 
 ```
 node scripts/validate-plugin.cjs
 node scripts/token-report.cjs --check
+node scripts/test-verify-evidence.cjs
 ```
 
+`scripts/verify-evidence.cjs` is the evidence gate itself — dogfooding the
+"every claim has evidence" philosophy against the agent's own output. It
+resolves `file:line` citations in an artifact (`--citations <file>`) and scans
+`git diff HEAD` for fake-green tampering — deleted test files, added test skips,
+new TODO/FIXME (`--tripwires`) — exiting non-zero when a claim can't be verified.
+
 ## Requirements
 
 - Claude Code 1.0+

scripts/test-verify-evidence.cjs

@@ -0,0 +1,344 @@
+#!/usr/bin/env node
+/**
+ * Test runner for verify-evidence.cjs (the evidence gate) and its fail-open
+ * hook wrapper verify-evidence-hook.cjs. Zero dependencies, no framework:
+ * builds hermetic fixtures in a temp dir, spawns the scripts, asserts exit
+ * codes. Exit 0 when every case passes, 1 otherwise. A missing script or
+ * spawn error counts as that case's FAIL — the run never aborts.
+ *
+ * Mirrors scripts/test-hooks.cjs conventions.
+ *
+ * Usage: node scripts/test-verify-evidence.cjs
+ */
+"use strict";
+
+const { spawnSync } = require("child_process");
+const fs = require("fs");
+const os = require("os");
+const path = require("path");
+
+const GATE = path.join(__dirname, "verify-evidence.cjs");
+const HOOK = path.join(__dirname, "verify-evidence-hook.cjs");
+
+let pass = 0;
+let fail = 0;
+const tmpRoots = [];
+
+function mkTmp() {
+  const d = fs.mkdtempSync(path.join(os.tmpdir(), "vee-"));
+  tmpRoots.push(d);
+  return d;
+}
+
+function runGate(args, { cwd, diffFile, env } = {}) {
+  const e = { ...process.env, ...env };
+  if (diffFile) e.VERIFY_EVIDENCE_DIFF_FILE = diffFile;
+  return spawnSync(process.execPath, [GATE, ...args], {
+    cwd: cwd || process.cwd(),
+    env: e,
+    encoding: "utf8",
+    timeout: 10000,
+  });
+}
+
+function runHook(stdin, { diffFile } = {}) {
+  const e = { ...process.env };
+  if (diffFile) e.VERIFY_EVIDENCE_DIFF_FILE = diffFile;
+  return spawnSync(process.execPath, [HOOK], {
+    input: stdin,
+    env: e,
+    encoding: "utf8",
+    timeout: 10000,
+  });
+}
+
+function check(name, result, expected) {
+  let status = null;
+  let err = "";
+  if (result.error) err = result.error.message;
+  else status = result.status;
+  const ok = !err && status === expected;
+  if (ok) {
+    pass++;
+    console.log(`  ✓ ${name} (exit ${status})`);
+  } else {
+    fail++;
+    console.log(`  ✗ ${name} — expected exit ${expected}, got ${err || `exit ${status}`}`);
+  }
+}
+
+// ---- helpers to build fixtures ----
+function citationDir(artifactBody, realFileLines) {
+  const dir = mkTmp();
+  if (realFileLines != null) {
+    fs.writeFileSync(path.join(dir, "real.js"), realFileLines.join("\n") + "\n");
+  }
+  fs.writeFileSync(path.join(dir, "artifact.md"), artifactBody);
+  return dir;
+}
+
+function diffFileWith(body) {
+  const dir = mkTmp();
+  const f = path.join(dir, "captured.diff");
+  fs.writeFileSync(f, body);
+  return f;
+}
+
+// A minimal unified-diff builder.
+function diffAdd(filePath, addedLines) {
+  return (
+    `diff --git a/${filePath} b/${filePath}\n` +
+    `index 111..222 100644\n` +
+    `--- a/${filePath}\n` +
+    `+++ b/${filePath}\n` +
+    `@@ -1,1 +1,${addedLines.length + 1} @@\n` +
+    ` context\n` +
+    addedLines.map((l) => `+${l}`).join("\n") +
+    "\n"
+  );
+}
+
+function diffDelete(filePath) {
+  return (
+    `diff --git a/${filePath} b/${filePath}\n` +
+    `deleted file mode 100644\n` +
+    `index 111..000\n` +
+    `--- a/${filePath}\n` +
+    `+++ /dev/null\n` +
+    `@@ -1,2 +0,0 @@\n` +
+    `-test('x', () => {});\n` +
+    `-test('y', () => {});\n`
+  );
+}
+
+function diffRename(fromPath, toPath) {
+  return (
+    `diff --git a/${fromPath} b/${toPath}\n` +
+    `similarity index 100%\n` +
+    `rename from ${fromPath}\n` +
+    `rename to ${toPath}\n`
+  );
+}
+
+const diffConcat = (...parts) => parts.join("");
+
+// ============ CITATION CASES ============
+console.log("\nverify-evidence.cjs --citations");
+{
+  const real = ["line one", "line two", "line three"];
+
+  check(
+    "valid single-line citation",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("Root caused in `real.js:2` per the trace.", real),
+    }),
+    0
+  );
+
+  check(
+    "valid range citation",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("See real.js:1-3 for the fix.", real),
+    }),
+    0
+  );
+
+  check(
+    "out-of-range line",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("Broken at real.js:999.", real),
+    }),
+    1
+  );
+
+  check(
+    "missing file",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("See gone.js:1 for detail.", real),
+    }),
+    1
+  );
+
+  check(
+    "absolute path citation is a violation",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("Config at /etc/hosts:1 shows it.", real),
+    }),
+    1
+  );
+
+  check(
+    "prose colons and URLs are not citations",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir(
+        "The ratio was 3:2 and we hit http://example.com:8080 at 12:30.",
+        real
+      ),
+    }),
+    0
+  );
+
+  check(
+    "decimal-colon prose (3.5:2) is not a citation",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("Throughput rose 3.5:2 over baseline, and 18.04:30 held.", real),
+    }),
+    0
+  );
+
+  check(
+    "last-line+1 on a newline-terminated file is out of range",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("See real.js:2 for the change.", ["only one line"]),
+    }),
+    1
+  );
+
+  check(
+    "no citations at all",
+    runGate(["--citations", "artifact.md"], {
+      cwd: citationDir("Just prose, nothing to resolve.", real),
+    }),
+    0
+  );
+}
+
+// ============ TRIPWIRE CASES ============
+console.log("\nverify-evidence.cjs --tripwires");
+{
+  check(
+    "added .skip in a test file",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("src/app.test.js", ["it.skip('later', () => {});"])) }),
+    1
+  );
+  check(
+    "added xit in a spec file",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("src/app.spec.js", ["xit('later', () => {});"])) }),
+    1
+  );
+  check(
+    "added @pytest.mark.skip",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("tests/test_app.py", ["@pytest.mark.skip(reason='x')"])) }),
+    1
+  );
+  check(
+    "added @unittest.skip",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("tests/test_app.py", ["@unittest.skip('x')"])) }),
+    1
+  );
+  check(
+    "added TODO in changed code",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("src/app.js", ["// TODO: implement for real"])) }),
+    1
+  );
+  check(
+    "added FIXME in changed code",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("src/app.js", ["# FIXME later"])) }),
+    1
+  );
+  check(
+    "deleted test file",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffDelete("tests/test_app.py")) }),
+    1
+  );
+  check(
+    "test renamed to another test path is fine",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffRename("tests/test_old.py", "tests/test_new.py")) }),
+    0
+  );
+  check(
+    "test renamed OUT of the suite is a violation",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffRename("tests/test_app.py", "src/app.py")) }),
+    1
+  );
+  check(
+    "added bare @skip decorator",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("tests/test_app.py", ["@skip"])) }),
+    1
+  );
+  check(
+    "multi-file diff: clean file then skip in a later file, attributed correctly",
+    runGate(["--tripwires"], {
+      diffFile: diffFileWith(
+        diffConcat(
+          diffAdd("src/util.js", ["const y = 2;"]),
+          diffAdd("src/util.test.js", ["it.skip('later', () => {});"])
+        )
+      ),
+    }),
+    1
+  );
+  check(
+    "multi-file diff: deleted non-test then clean adds does not false-flag",
+    runGate(["--tripwires"], {
+      diffFile: diffFileWith(diffConcat(diffDelete("src/legacy.js"), diffAdd("src/new.js", ["const z = 3;"]))),
+    }),
+    0
+  );
+  check(
+    "clean diff of normal code",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffAdd("src/app.js", ["const x = 1;", "return x;"])) }),
+    0
+  );
+  check(
+    "empty diff",
+    runGate(["--tripwires"], { diffFile: diffFileWith("") }),
+    0
+  );
+  check(
+    "deleting a NON-test file is fine",
+    runGate(["--tripwires"], { diffFile: diffFileWith(diffDelete("src/legacy.js")) }),
+    0
+  );
+  check(
+    "no git and no diff file -> skipped, not a failure",
+    runGate(["--tripwires"], { cwd: mkTmp() }),
+    0
+  );
+}
+
+// ============ COMBINED / NO-FLAG / HELP ============
+console.log("\nverify-evidence.cjs combined & meta");
+{
+  const dir = citationDir("Broken at real.js:999.", ["a", "b"]);
+  check(
+    "combined: bad citation + skip tripwire -> exit 1",
+    runGate(["--citations", "artifact.md", "--tripwires"], {
+      cwd: dir,
+      diffFile: diffFileWith(diffAdd("a.test.js", ["it.skip('x', () => {})"])),
+    }),
+    1
+  );
+  check(
+    "no flags runs tripwires (clean diff) -> exit 0",
+    runGate([], { cwd: mkTmp(), diffFile: diffFileWith("") }),
+    0
+  );
+  check("--help exits 0", runGate(["--help"]), 0);
+}
+
+// ============ HOOK (fail-open) ============
+console.log("\nverify-evidence-hook.cjs (always exit 0)");
+{
+  const stop = JSON.stringify({ hook_event_name: "Stop" });
+  check("valid stop event, clean diff", runHook(stop, { diffFile: diffFileWith("") }), 0);
+  check(
+    "violation present -> hook still exits 0 (advisory)",
+    runHook(stop, { diffFile: diffFileWith(diffAdd("a.test.js", ["it.skip('x', () => {})"])) }),
+    0
+  );
+  check("malformed stdin -> exit 0", runHook("{not json", {}), 0);
+  check("empty stdin -> exit 0", runHook("", {}), 0);
+}
+
+// ---- cleanup ----
+for (const d of tmpRoots) {
+  try {
+    fs.rmSync(d, { recursive: true, force: true });
+  } catch {
+    /* best effort */
+  }
+}
+
+console.log(`\n${fail === 0 ? "OK" : "FAIL"} — ${pass} passed, ${fail} failed`);
+process.exit(fail === 0 ? 0 : 1);

scripts/verify-evidence-hook.cjs

@@ -0,0 +1,46 @@
+#!/usr/bin/env node
+/**
+ * Fail-open hook wrapper around the evidence gate (scripts/verify-evidence.cjs).
+ * Intended for a Stop / PostToolUse hook: after the agent claims work is done,
+ * run the tripwire scan and surface any fake-green findings as ADVISORY output
+ * — it never blocks and never exits non-zero on its own errors.
+ *
+ * Fails open (exit 0 always), per the repo's hook convention
+ * (see scripts/auto-format.cjs, scripts/detect-secrets.cjs). The loud,
+ * blocking enforcement lives in verify-evidence.cjs run as a CI gate; this
+ * wrapper is the low-friction in-session nudge.
+ */
+"use strict";
+
+const path = require("path");
+const { spawnSync } = require("child_process");
+
+async function main() {
+  try {
+    // Drain stdin (hook payload); content is not needed for the diff scan.
+    let data = "";
+    for await (const chunk of process.stdin) data += chunk;
+    try {
+      JSON.parse(data);
+    } catch {
+      // Malformed / empty payload is fine — this hook fires opportunistically.
+    }
+
+    const gate = path.join(__dirname, "verify-evidence.cjs");
+    const r = spawnSync(process.execPath, [gate, "--tripwires"], {
+      encoding: "utf8",
+      timeout: 10000,
+    });
+
+    // Exit 1 from the gate means tripwires were found — surface them, advisory.
+    if (r.status === 1 && (r.stderr || r.stdout)) {
+      console.error("[evidence] fake-green tripwires detected (advisory):");
+      console.error(r.stderr || r.stdout);
+    }
+  } catch {
+    // Fail open — a hook bug must never stall or block the session.
+  }
+  process.exit(0);
+}
+
+main();

scripts/verify-evidence.cjs

@@ -0,0 +1,334 @@
+#!/usr/bin/env node
+/**
+ * Evidence gate: mechanically checks that an AI agent's *claimed* evidence is
+ * real, rather than trusting the transcript. Two modes:
+ *
+ *   --citations <artifact.md>  Resolve `file:line` / `file:start-end` citations
+ *                              in an evidence artifact; fail if a path is
+ *                              missing, absolute/outside the repo, or the line
+ *                              is out of range.
+ *   --tripwires                Scan `git diff HEAD` for fake-green tampering:
+ *                              deleted test files, newly skipped tests, and new
+ *                              TODO/FIXME left in changed code.
+ *
+ * With no mode flag, runs --tripwires (citations need an artifact argument).
+ *
+ * This is a GATE, not a convenience hook: it fails loud.
+ *   exit 0 = clean   exit 1 = violations found   exit 2 = usage / internal error
+ * (Exit 2 is kept distinct from 1 so a crash can never masquerade as a
+ * "violation", per scripts/test-verify-evidence.cjs.)
+ *
+ * Precision-first by design: it would rather miss an oddly-shaped citation or an
+ * unusually-named test than cry wolf — a gate that cries wolf gets disabled. It
+ * deliberately does NOT attempt deep test-tamper analysis (assertion-count
+ * deltas, mutation proofs); that is out of scope for this slice.
+ *
+ * Zero dependencies. Usage: node scripts/verify-evidence.cjs [--citations <f>] [--tripwires]
+ */
+"use strict";
+
+const fs = require("fs");
+const path = require("path");
+const { spawnSync } = require("child_process");
+
+const USAGE =
+  "Usage: node scripts/verify-evidence.cjs [--citations <artifact.md>] [--tripwires]";
+
+// ---------------------------------------------------------------- citations
+// A citation is `path:line` or `path:start-end`, backtick-optional. To avoid
+// false positives from prose ("ratio 3:2", "12:30") and URLs, the path token
+// must contain a "." or "/", URLs are stripped first, and a match preceded by a
+// word char or ":" is rejected.
+const CITATION_RE =
+  /(?<![\w:])(\/?[A-Za-z0-9._-]+(?:\/[A-Za-z0-9._-]+)*):(\d+)(?:-(\d+))?(?![\d-])/g;
+
+function findCitations(text) {
+  const stripped = text.replace(/\bhttps?:\/\/\S+/gi, " ");
+  const out = [];
+  let m;
+  CITATION_RE.lastIndex = 0;
+  while ((m = CITATION_RE.exec(stripped)) !== null) {
+    const p = m[1];
+    // Path-like only: contains a "/" or a letter-led extension (".js", ".py").
+    // A dotted number like "3.5" (in prose "ratio 3.5:2") is NOT a path.
+    if (!p.includes("/") && !/\.[A-Za-z]/.test(p)) continue;
+    out.push({
+      raw: m[0],
+      filePath: p,
+      start: parseInt(m[2], 10),
+      end: m[3] ? parseInt(m[3], 10) : parseInt(m[2], 10),
+    });
+  }
+  return out;
+}
+
+// Repo root so citations resolve the same way regardless of the cwd the gate
+// is run from; falls back to cwd when not in a git work tree (e.g. tests).
+function repoRoot() {
+  const r = spawnSync("git", ["rev-parse", "--show-toplevel"], {
+    encoding: "utf8",
+    timeout: 10000,
+  });
+  if (!r.error && r.status === 0 && r.stdout.trim()) {
+    try {
+      return fs.realpathSync(r.stdout.trim());
+    } catch {
+      /* fall through */
+    }
+  }
+  return fs.realpathSync(process.cwd());
+}
+
+function checkCitations(artifactArg) {
+  const violations = [];
+  let artifactText;
+  try {
+    artifactText = fs.readFileSync(artifactArg, "utf8");
+  } catch {
+    return { usageError: `cannot read artifact: ${artifactArg}` };
+  }
+  const base = repoRoot();
+  const citations = findCitations(artifactText);
+
+  for (const c of citations) {
+    if (path.isAbsolute(c.filePath)) {
+      violations.push(`${c.raw} — absolute path, cannot verify against repo`);
+      continue;
+    }
+    const full = path.resolve(base, c.filePath);
+    if (!fs.existsSync(full)) {
+      violations.push(`${c.raw} — cited file does not exist`);
+      continue;
+    }
+    let realFull;
+    try {
+      realFull = fs.realpathSync(full);
+    } catch {
+      violations.push(`${c.raw} — cited file does not exist`);
+      continue;
+    }
+    if (realFull !== base && !realFull.startsWith(base + path.sep)) {
+      violations.push(`${c.raw} — resolves outside the repository`);
+      continue;
+    }
+    let stat;
+    try {
+      stat = fs.statSync(realFull);
+    } catch {
+      violations.push(`${c.raw} — cited file does not exist`);
+      continue;
+    }
+    if (!stat.isFile()) {
+      violations.push(`${c.raw} — citation does not point at a file`);
+      continue;
+    }
+    const body = fs.readFileSync(realFull, "utf8");
+    // Count real lines: a single trailing newline is a terminator, not a line.
+    const lineCount = body === "" ? 0 : body.replace(/\n$/, "").split("\n").length;
+    if (c.start < 1 || c.end < c.start || c.end > lineCount) {
+      violations.push(
+        `${c.raw} — line out of range (file has ${lineCount} lines)`
+      );
+    }
+  }
+  return { violations, checked: citations.length };
+}
+
+// ---------------------------------------------------------------- tripwires
+function isTestFile(p) {
+  const f = p.toLowerCase();
+  return (
+    /(^|\/)tests?\//.test(f) ||
+    /(^|\/)__tests__\//.test(f) ||
+    /\.(test|spec)\.[a-z0-9]+$/.test(f) ||
+    /(^|\/)test_[^/]*\.py$/.test(f) ||
+    /_test\.py$/.test(f) ||
+    // "test"/"spec" as a separator-bounded token in the basename — catches
+    // e.g. app.test.js, foo_spec.rb, but not latest.js / inspector.js.
+    /(^|[\/._-])(test|spec)([\/._-]|$)/.test(f)
+  );
+}
+
+const SKIP_PATTERNS = [
+  { name: "skipped test (.skip)", re: /\.skip\s*\(/ },
+  { name: "skipped test (xit/xdescribe/xtest)", re: /\bx(it|describe|test)\s*\(/ },
+  // Matches @skip, @pytest.mark.skip, @pytest.mark.skipif, @unittest.skip,
+  // @unittest.skipUnless, @unittest.skipIf.
+  { name: "skipped test (@skip decorator)", re: /@(?:pytest\.mark\.|unittest\.)?skip/ },
+];
+const MARKER_RE = /\b(TODO|FIXME)\b/;
+
+function getDiff() {
+  const override = process.env.VERIFY_EVIDENCE_DIFF_FILE;
+  if (override) {
+    try {
+      return { text: fs.readFileSync(override, "utf8") };
+    } catch {
+      return { unavailable: `cannot read VERIFY_EVIDENCE_DIFF_FILE: ${override}` };
+    }
+  }
+  const r = spawnSync("git", ["diff", "HEAD"], { encoding: "utf8", timeout: 10000 });
+  if (r.error || r.status !== 0) {
+    return { unavailable: "git diff HEAD unavailable (not a git repo?)" };
+  }
+  return { text: r.stdout || "" };
+}
+
+function checkTripwires() {
+  const diff = getDiff();
+  if (diff.unavailable) return { skipped: diff.unavailable };
+
+  const violations = [];
+  const lines = diff.text.split("\n");
+  let aPath = null;
+  let bPath = null;
+  let curFile = null;
+  let newLineNo = 0;
+  let renameFrom = null;
+
+  const stripPrefix = (s) =>
+    s === "/dev/null" ? "/dev/null" : s.replace(/^[ab]\//, "");
+
+  for (const line of lines) {
+    // A new file section resets all per-file state, so location and deletion
+    // attribution never leak across files in a multi-file diff.
+    if (line.startsWith("diff --git ")) {
+      aPath = null;
+      bPath = null;
+      curFile = null;
+      newLineNo = 0;
+      renameFrom = null;
+      continue;
+    }
+    if (line.startsWith("rename from ")) {
+      renameFrom = line.slice("rename from ".length).trim();
+      continue;
+    }
+    if (line.startsWith("rename to ")) {
+      const renameTo = line.slice("rename to ".length).trim();
+      // Renaming a test file to a non-test path removes it from the suite.
+      if (renameFrom && isTestFile(renameFrom) && !isTestFile(renameTo)) {
+        violations.push(`test file renamed out of the suite: ${renameFrom} → ${renameTo}`);
+      }
+      continue;
+    }
+    if (line.startsWith("--- ")) {
+      aPath = stripPrefix(line.slice(4).trim());
+      continue;
+    }
+    if (line.startsWith("+++ ")) {
+      bPath = stripPrefix(line.slice(4).trim());
+      curFile = bPath === "/dev/null" ? aPath : bPath;
+      // A file whose new side is /dev/null was deleted.
+      if (bPath === "/dev/null" && aPath && isTestFile(aPath)) {
+        violations.push(`deleted test file: ${aPath}`);
+      }
+      continue;
+    }
+    const hunk = /^@@ -\d+(?:,\d+)? \+(\d+)(?:,\d+)? @@/.exec(line);
+    if (hunk) {
+      newLineNo = parseInt(hunk[1], 10);
+      continue;
+    }
+    // Added content line (not the "+++ " file header, handled above).
+    if (line.startsWith("+")) {
+      const content = line.slice(1);
+      const loc = curFile ? `${curFile}:${newLineNo}` : "(unknown)";
+      for (const s of SKIP_PATTERNS) {
+        if (s.re.test(content)) violations.push(`${s.name} added at ${loc}`);
+      }
+      if (MARKER_RE.test(content)) {
+        violations.push(`TODO/FIXME added at ${loc}: ${content.trim()}`);
+      }
+      newLineNo++;
+      continue;
+    }
+    if (line.startsWith(" ")) {
+      newLineNo++;
+      continue;
+    }
+    // "-" lines and metadata: no new-side advance
+  }
+  return { violations };
+}
+
+// ---------------------------------------------------------------- main
+function main() {
+  const argv = process.argv.slice(2);
+  if (argv.includes("--help") || argv.includes("-h")) {
+    console.log(USAGE);
+    return 0;
+  }
+
+  let artifact = null;
+  let doCitations = false;
+  let doTripwires = false;
+  for (let i = 0; i < argv.length; i++) {
+    if (argv[i] === "--citations") {
+      doCitations = true;
+      artifact = argv[i + 1] && !argv[i + 1].startsWith("-") ? argv[++i] : null;
+    } else if (argv[i] === "--tripwires") {
+      doTripwires = true;
+    } else {
+      console.error(`Unknown argument: ${argv[i]}\n${USAGE}`);
+      return 2;
+    }
+  }
+  // Default: no mode flag → tripwires (citations require an artifact arg).
+  if (!doCitations && !doTripwires) doTripwires = true;
+
+  const findings = [];
+  let anyViolation = false;
+
+  if (doCitations) {
+    if (!artifact) {
+      console.error(`--citations requires an artifact path\n${USAGE}`);
+      return 2;
+    }
+    const res = checkCitations(artifact);
+    if (res.usageError) {
+      console.error(res.usageError);
+      return 2;
+    }
+    if (res.violations.length) {
+      anyViolation = true;
+      findings.push(
+        `citations: ${res.violations.length} unresolved of ${res.checked} checked`
+      );
+      for (const v of res.violations) findings.push(`  ✗ ${v}`);
+    } else {
+      findings.push(`citations: ${res.checked} checked, all resolve`);
+    }
+  }
+
+  if (doTripwires) {
+    const res = checkTripwires();
+    if (res.skipped) {
+      findings.push(`tripwires: skipped — ${res.skipped}`);
+    } else if (res.violations.length) {
+      anyViolation = true;
+      findings.push(`tripwires: ${res.violations.length} found`);
+      for (const v of res.violations) findings.push(`  ✗ ${v}`);
+    } else {
+      findings.push(`tripwires: none`);
+    }
+  }
+
+  const out = findings.join("\n");
+  if (anyViolation) {
+    console.error(out);
+    console.error("\nFAIL — evidence gate found unverifiable claims.");
+    return 1;
+  }
+  console.log(out);
+  console.log("\nOK — evidence gate passed.");
+  return 0;
+}
+
+try {
+  process.exit(main());
+} catch (err) {
+  // Internal error is exit 2, never 1 — a crash must not read as a violation.
+  console.error(`verify-evidence: internal error: ${err && err.message}`);
+  process.exit(2);
+}