diff --git a/package.json b/package.json
index 9be39cb..6c8326f 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,9 @@
     "format": "biome format --write src/",
     "format:check": "biome format src/",
     "biome": "biome check src/",
-    "biome:fix": "biome check --write src/"
+    "biome:fix": "biome check --write src/",
+    "int9:guard": "node scripts/int9-guard.mjs",
+    "int9:guard:self-test": "node scripts/int9-guard.mjs --self-test"
   },
   "dependencies": {
     "@paperclipai/plugin-sdk": "^2026.722.0",
diff --git a/scripts/fixtures/int9/allowed-inside-job.ts b/scripts/fixtures/int9/allowed-inside-job.ts
new file mode 100644
index 0000000..7f732c8
--- /dev/null
+++ b/scripts/fixtures/int9/allowed-inside-job.ts
@@ -0,0 +1,16 @@
+// פיקסצ'ר ל-scripts/int9-guard.mjs --self-test. לא קוד-ריצה.
+//
+// קריאה ל-issues.update({status}) בתוך jobs.register("sync-case-status", …)
+// — המסלול המותר היחיד. כולל תבנית עם סוגריים לא-מאוזנים בתוך תבנית-מחרוזת
+// והערה, כדי לבחון בפועל את הטוקנייזר (מחרוזת/הערה לא נספרות ב-matchParen).
+
+export function register(ctx: any, api: any) {
+	ctx.jobs.register("sync-case-status", async (job: unknown) => {
+		// סוגר בודד בהערה — לא אמור לבלבל את חישוב-הטווח: )
+		const label = `📋 (${api.name}`;
+
+		const target = await api.pickTarget();
+
+		await ctx.issues.update(target.id, { status: label }, target.companyId);
+	});
+}
diff --git a/scripts/fixtures/int9/non-status-update.ts b/scripts/fixtures/int9/non-status-update.ts
new file mode 100644
index 0000000..6531f31
--- /dev/null
+++ b/scripts/fixtures/int9/non-status-update.ts
@@ -0,0 +1,15 @@
+// פיקסצ'ר ל-scripts/int9-guard.mjs --self-test. לא קוד-ריצה.
+//
+// שתי קריאות ל-issues.update שאינן נוגעות ב-status כלל — לא הפרה.
+// השנייה בודקת שגבול-מילה אמיתי: "statusLabel" אינו תואם ל-/\bstatus\b/
+// (אין גבול-מילה בין ה-s של status ל-L של Label).
+
+export async function renameOnly(ctx: any, target: any, statusLabel: string) {
+	await ctx.issues.update(target.id, { title: "x" }, target.companyId);
+
+	await ctx.issues.update(
+		target.id,
+		{ description: statusLabel },
+		target.companyId,
+	);
+}
diff --git a/scripts/fixtures/int9/noqa-bare.ts b/scripts/fixtures/int9/noqa-bare.ts
new file mode 100644
index 0000000..4ea2bef
--- /dev/null
+++ b/scripts/fixtures/int9/noqa-bare.ts
@@ -0,0 +1,9 @@
+// פיקסצ'ר ל-scripts/int9-guard.mjs --self-test. לא קוד-ריצה.
+//
+// קריאה ל-issues.update({status}) מחוץ ל-sync-case-status, עם noqa בלי נימוק —
+// עדיין הפרה (AC3: חריגה חייבת להיות מנומקת בכתב).
+
+export async function sloppyBackfill(ctx: any, target: any) {
+	// noqa: INT9
+	await ctx.issues.update(target.id, { status: "done" }, target.companyId);
+}
diff --git a/scripts/fixtures/int9/noqa-justified.ts b/scripts/fixtures/int9/noqa-justified.ts
new file mode 100644
index 0000000..b135fb2
--- /dev/null
+++ b/scripts/fixtures/int9/noqa-justified.ts
@@ -0,0 +1,9 @@
+// פיקסצ'ר ל-scripts/int9-guard.mjs --self-test. לא קוד-ריצה.
+//
+// קריאה ל-issues.update({status}) מחוץ ל-sync-case-status, עם חריגה מנומקת —
+// מותר.
+
+export async function migrationBackfill(ctx: any, target: any) {
+	// noqa: INT9 — מיגרציה חד-פעמית לתיקון סטטוסים תקועים מלפני #618, מאושרת ע"י דפנה
+	await ctx.issues.update(target.id, { status: "done" }, target.companyId);
+}
diff --git a/scripts/fixtures/int9/violating.ts b/scripts/fixtures/int9/violating.ts
new file mode 100644
index 0000000..b339467
--- /dev/null
+++ b/scripts/fixtures/int9/violating.ts
@@ -0,0 +1,16 @@
+// פיקסצ'ר ל-scripts/int9-guard.mjs --self-test. לא קוד-ריצה.
+//
+// קריאה ל-issues.update({status}) מחוץ לכל jobs.register("sync-case-status", …)
+// — זו בדיוק ההפרה שהשער אמור לתפוס.
+
+export async function badHandler(ctx: any, target: any) {
+	await ctx.jobs.register("stale-case-reminder", async (_job: unknown) => {
+		ctx.logger.info("stale-case-reminder: starting");
+	});
+
+	await ctx.issues.update(
+		target.id,
+		{ status: "in_progress" },
+		target.companyId,
+	);
+}
diff --git a/scripts/int9-guard.mjs b/scripts/int9-guard.mjs
new file mode 100644
index 0000000..811e666
--- /dev/null
+++ b/scripts/int9-guard.mjs
@@ -0,0 +1,546 @@
+#!/usr/bin/env node
+/**
+ * INV-INT9 guard — enforce single write-ownership of `issue.status`
+ * (legal-ai docs/spec/X7-paperclip-client-params.md §4 INV-INT9).
+ *
+ * `issues.status` has exactly one legitimate writer in this plugin: the
+ * `sync-case-status` scheduled job (`ctx.jobs.register("sync-case-status", …)`
+ * in `src/worker.ts`), which mirrors legal-ai's case status onto the linked
+ * Paperclip issue. Any OTHER `ctx.issues.update(...)` call that touches
+ * `status` is a second writer racing the sync job — exactly the flip-flop
+ * (`done` → `in_progress`) bug class legal-ai issue #618 exists to close off
+ * for good, before a second call site is ever added.
+ *
+ * IN SCOPE: every `.ts`/`.tsx` file under `src/` (including `*.test.ts` —
+ * there is no false positive there today, and the noqa escape hatch below
+ * covers the day there is one).
+ *
+ * OUT OF SCOPE: this is NOT a general call-graph analysis. It is a
+ * structural, single-pass lexer over the source text — no type information,
+ * no cross-file resolution. It answers exactly one question per call site:
+ * "does the character range of this `ctx.issues.update(...)` call sit
+ * inside the character range of the one whitelisted
+ * `ctx.jobs.register("sync-case-status", …)` call?". Deliberately NOT a
+ * per-file allowlist (the pattern `scripts/leak_guard.py` in legal-ai uses)
+ * — that shape does not fit here, because the one legitimate call site and
+ * every future illegitimate one live in the very same file (`worker.ts`).
+ * The granularity has to be a code RANGE derived from the real structure,
+ * not a file name.
+ *
+ * Escape hatch (G1 — fix at the source, don't paper over a false positive):
+ * a call can be justified in place with
+ *     // noqa: INT9 — <reason, at least 3 characters>
+ * on the line immediately above the call, or on any line spanned by its
+ * argument list. A bare `// noqa: INT9` with no reason is itself a
+ * violation (AC3 — exceptions must be justified in writing, not silent).
+ *
+ * Usage:
+ *   node scripts/int9-guard.mjs                 # scan src/**\/*.{ts,tsx}; exit 1 on any violation
+ *   node scripts/int9-guard.mjs <path>...        # scan only the given files/directories
+ *   node scripts/int9-guard.mjs --self-test      # run the fixture suite (scripts/fixtures/int9/), prove the gate bites
+ *
+ * NOT WIRED INTO CI YET: the Gitea Actions runner on this server is
+ * registered at *repository* scope for `legal-ai` only
+ * (`action_runner.repo_id = 6`), so any job queued for `plugin-legal-ai` is
+ * never dispatched — measured on legal-ai issue #618, run 3200 / job 3250
+ * sat in `queued` with `started_at: 1970-01-01`. Until a runner is
+ * registered for this repo, run this by hand:
+ *     npm run int9:guard
+ *     npm run int9:guard:self-test
+ * The workflow file itself (`.gitea/workflows/int9-guard.yaml`) lives in a
+ * separate, deliberately-blocked PR, so merging it does not leave a
+ * permanently-pending check on every future PR in this repo.
+ *
+ * Zero dependencies (node:fs / node:path / node:process only) — no `npm ci`
+ * needed in CI; the runner image ships node 24.
+ */
+import { readdirSync, readFileSync, statSync } from "node:fs";
+import { join, relative, resolve } from "node:path";
+import process from "node:process";
+
+const REPO_ROOT = resolve(import.meta.dirname, "..");
+const SKIP_DIRS = new Set(["node_modules", "dist", ".git"]);
+const SOURCE_EXT = new Set([".ts", ".tsx"]);
+
+const SPEC_REF = "docs/spec/X7-paperclip-client-params.md §4 INV-INT9";
+
+const NOQA_RE = /\/\/\s*noqa\s*:\s*INT9\b(?:\s*[-—]\s*(.*))?/i;
+
+const REGEX_PREV_CHARS = new Set("(,=:[!&|?{};+-*%~^<>".split(""));
+const REGEX_PREV_WORDS = new Set([
+	"return",
+	"typeof",
+	"case",
+	"in",
+	"of",
+	"new",
+	"delete",
+	"void",
+	"instanceof",
+	"do",
+	"else",
+	"yield",
+	"await",
+]);
+
+// ---------------------------------------------------------------------
+// Tokenizer — classify every character as "plain code" or not, so that
+// structural regexes and paren-matching never see string/template
+// contents, comments, or regex-literal bodies.
+// ---------------------------------------------------------------------
+
+/** @returns {Uint8Array} mask[i] === 1 iff text[i] is plain code. */
+function classify(text) {
+	const n = text.length;
+	const mask = new Uint8Array(n);
+	/** @type {Array<{kind: "template"} | {kind: "exprCode", depth: number}>} */
+	const stack = [];
+	let state = "code";
+	let lastSignificant = "";
+	let lastWord = "";
+	let i = 0;
+
+	function noteCodeChar(ch) {
+		if (/\s/.test(ch)) return;
+		lastSignificant = ch;
+		if (/[A-Za-z0-9_$]/.test(ch)) {
+			lastWord += ch;
+		} else {
+			lastWord = "";
+		}
+	}
+
+	while (i < n) {
+		const ch = text[i];
+
+		if (state === "code") {
+			const next = text[i + 1];
+			if (ch === "/" && next === "/") {
+				state = "lcomment";
+				i += 2;
+				continue;
+			}
+			if (ch === "/" && next === "*") {
+				state = "bcomment";
+				i += 2;
+				continue;
+			}
+			if (ch === "'") {
+				state = "squote";
+				i += 1;
+				continue;
+			}
+			if (ch === '"') {
+				state = "dquote";
+				i += 1;
+				continue;
+			}
+			if (ch === "`") {
+				stack.push({ kind: "template" });
+				state = "template";
+				i += 1;
+				continue;
+			}
+			if (ch === "/") {
+				const isRegex =
+					lastSignificant === "" ||
+					REGEX_PREV_CHARS.has(lastSignificant) ||
+					REGEX_PREV_WORDS.has(lastWord);
+				if (isRegex) {
+					state = "regex";
+					i += 1;
+					continue;
+				}
+				// else: division — falls through to plain-code handling below.
+			}
+
+			mask[i] = 1;
+			const top = stack[stack.length - 1];
+			if (ch === "{" && top && top.kind === "exprCode") {
+				top.depth += 1;
+			} else if (ch === "}" && top && top.kind === "exprCode") {
+				top.depth -= 1;
+				if (top.depth === 0) {
+					stack.pop();
+					state = "template";
+				}
+			}
+			noteCodeChar(ch);
+			i += 1;
+			continue;
+		}
+
+		if (state === "squote" || state === "dquote") {
+			const quote = state === "squote" ? "'" : '"';
+			if (ch === "\\") {
+				i += 2;
+				continue;
+			}
+			if (ch === quote) {
+				state = "code";
+				noteCodeChar(quote);
+				i += 1;
+				continue;
+			}
+			if (ch === "\n") {
+				// Unterminated string — bail back to code rather than eat the file.
+				state = "code";
+				i += 1;
+				continue;
+			}
+			i += 1;
+			continue;
+		}
+
+		if (state === "template") {
+			if (ch === "\\") {
+				i += 2;
+				continue;
+			}
+			if (ch === "`") {
+				stack.pop();
+				state = "code";
+				i += 1;
+				continue;
+			}
+			if (ch === "$" && text[i + 1] === "{") {
+				stack.push({ kind: "exprCode", depth: 1 });
+				state = "code";
+				i += 2;
+				continue;
+			}
+			i += 1;
+			continue;
+		}
+
+		if (state === "lcomment") {
+			if (ch === "\n") {
+				state = "code";
+				i += 1;
+				continue;
+			}
+			i += 1;
+			continue;
+		}
+
+		if (state === "bcomment") {
+			if (ch === "*" && text[i + 1] === "/") {
+				state = "code";
+				i += 2;
+				continue;
+			}
+			i += 1;
+			continue;
+		}
+
+		if (state === "regex") {
+			if (ch === "\\") {
+				i += 2;
+				continue;
+			}
+			if (ch === "[") {
+				state = "regexclass";
+				i += 1;
+				continue;
+			}
+			if (ch === "/") {
+				i += 1;
+				while (i < n && /[a-z]/i.test(text[i])) i += 1;
+				state = "code";
+				continue;
+			}
+			if (ch === "\n") {
+				// Unterminated regex — bail back to code rather than eat the file.
+				state = "code";
+				i += 1;
+				continue;
+			}
+			i += 1;
+			continue;
+		}
+
+		if (state === "regexclass") {
+			if (ch === "\\") {
+				i += 2;
+				continue;
+			}
+			if (ch === "]") {
+				state = "regex";
+				i += 1;
+				continue;
+			}
+			i += 1;
+			continue;
+		}
+
+		// Unreachable, but never silently drop a character.
+		i += 1;
+	}
+
+	return mask;
+}
+
+/** Yield regex matches whose full span lies entirely in plain-code region. */
+function* matchAllCode(text, mask, pattern) {
+	for (const m of text.matchAll(pattern)) {
+		const start = m.index;
+		const end = start + m[0].length;
+		let allCode = true;
+		for (let i = start; i < end; i++) {
+			if (!mask[i]) {
+				allCode = false;
+				break;
+			}
+		}
+		if (allCode) yield m;
+	}
+}
+
+/** Index of the `)` matching the `(` at `openIndex`, counting only plain-code parens. */
+function matchParen(text, mask, openIndex, filePath) {
+	let depth = 0;
+	for (let i = openIndex; i < text.length; i++) {
+		if (!mask[i]) continue;
+		if (text[i] === "(") depth += 1;
+		else if (text[i] === ")") {
+			depth -= 1;
+			if (depth === 0) return i;
+		}
+	}
+	throw new Error(`${filePath}: פענוח נכשל — סוגר לא נסגר`);
+}
+
+function buildLineStarts(text) {
+	const starts = [0];
+	for (let i = 0; i < text.length; i++) {
+		if (text[i] === "\n") starts.push(i + 1);
+	}
+	return starts;
+}
+
+function lineOfOffset(lineStarts, idx) {
+	let lo = 0;
+	let hi = lineStarts.length - 1;
+	while (lo < hi) {
+		const mid = (lo + hi + 1) >> 1;
+		if (lineStarts[mid] <= idx) lo = mid;
+		else hi = mid - 1;
+	}
+	return lo; // 0-based line number
+}
+
+const STATUS_WORD_RE = /\bstatus\b/;
+const JOBS_REGISTER_RE = /jobs\.register\s*\(/g;
+const ISSUES_UPDATE_RE = /issues\.update\s*\(/g;
+const SYNC_CASE_STATUS_LITERAL_RE = /^\s*["']sync-case-status["']/;
+
+/**
+ * Scan one file's source text and return a list of violation objects
+ * ({ file, line, message }). Throws if a `(` is never closed (see
+ * matchParen) — the caller must NOT treat that as "no violations".
+ */
+function scanFile(filePath, text) {
+	const mask = classify(text);
+	const lines = text.split("\n");
+	const lineStarts = buildLineStarts(text);
+	const rel = filePath;
+
+	const allowedRanges = [];
+	for (const m of matchAllCode(text, mask, JOBS_REGISTER_RE)) {
+		const openIdx = m.index + m[0].length - 1;
+		const after = text.slice(openIdx + 1, openIdx + 60);
+		if (SYNC_CASE_STATUS_LITERAL_RE.test(after)) {
+			const closeIdx = matchParen(text, mask, openIdx, rel);
+			allowedRanges.push([openIdx, closeIdx]);
+		}
+	}
+
+	const violations = [];
+	for (const m of matchAllCode(text, mask, ISSUES_UPDATE_RE)) {
+		const openIdx = m.index + m[0].length - 1;
+		const closeIdx = matchParen(text, mask, openIdx, rel);
+		const content = text.slice(openIdx + 1, closeIdx);
+		if (!STATUS_WORD_RE.test(content)) continue; // not a status-write call
+
+		const inAllowedRange = allowedRanges.some(
+			([s, e]) => openIdx >= s && openIdx <= e,
+		);
+		if (inAllowedRange) continue;
+
+		const callStartLine = lineOfOffset(lineStarts, m.index);
+		const callEndLine = lineOfOffset(lineStarts, closeIdx);
+
+		let noqaMatch;
+		for (let ln = callStartLine - 1; ln <= callEndLine && !noqaMatch; ln += 1) {
+			if (ln < 0 || ln >= lines.length) continue;
+			const m2 = NOQA_RE.exec(lines[ln]);
+			if (m2) noqaMatch = m2;
+		}
+
+		const reportLine = callStartLine + 1; // 1-based for humans
+		if (noqaMatch) {
+			const reason = (noqaMatch[1] ?? "").trim();
+			if (reason.length >= 3) continue; // justified exception — allowed
+			violations.push({
+				file: rel,
+				line: reportLine,
+				message: "noqa: INT9 ללא נימוק — חריגה חייבת להיות מנומקת בכתב (AC3)",
+			});
+			continue;
+		}
+
+		violations.push({
+			file: rel,
+			line: reportLine,
+			message:
+				`issues.update({status}) מחוץ למסלול sync-case-status (INV-INT9). ` +
+				`ראה ${SPEC_REF}. חריגה מוצדקת → // noqa: INT9 — <נימוק>.`,
+		});
+	}
+
+	return violations;
+}
+
+// ---------------------------------------------------------------------
+// File collection
+// ---------------------------------------------------------------------
+
+function walk(dir, out) {
+	for (const entry of readdirSync(dir, { withFileTypes: true })) {
+		if (SKIP_DIRS.has(entry.name)) continue;
+		const full = join(dir, entry.name);
+		if (entry.isDirectory()) {
+			walk(full, out);
+		} else if (SOURCE_EXT.has(entry.name.slice(entry.name.lastIndexOf(".")))) {
+			out.push(full);
+		}
+	}
+	return out;
+}
+
+function collectDefault() {
+	const srcDir = join(REPO_ROOT, "src");
+	return walk(srcDir, []);
+}
+
+function collectFromArgs(args) {
+	const out = [];
+	for (const a of args) {
+		const p = resolve(a);
+		const st = statSync(p);
+		if (st.isDirectory()) {
+			walk(p, out);
+		} else {
+			out.push(p);
+		}
+	}
+	return out;
+}
+
+function runGate(files) {
+	const violations = [];
+	for (const abs of files) {
+		const rel = relative(REPO_ROOT, abs);
+		const text = readFileSync(abs, "utf-8");
+		violations.push(...scanFile(rel, text));
+	}
+	return violations;
+}
+
+function reportGate(violations, scannedCount) {
+	if (violations.length > 0) {
+		process.stderr.write(
+			`✗ INV-INT9 gate — issue.status write-ownership violated ` +
+				`(${violations.length} finding(s)):\n\n`,
+		);
+		for (const v of violations) {
+			process.stderr.write(`  • ${v.file}:${v.line}: ${v.message}\n`);
+		}
+		process.stderr.write(`\nSee ${SPEC_REF}.\n`);
+		return 1;
+	}
+	process.stdout.write(
+		`✓ INV-INT9 gate: מסלול-כתיבה יחיד ל-issue.status ` +
+			`(${scannedCount} קבצים נסרקו).\n`,
+	);
+	return 0;
+}
+
+// ---------------------------------------------------------------------
+// Self-test
+// ---------------------------------------------------------------------
+
+const SELF_TEST_EXPECTED = {
+	"violating.ts": 1,
+	"allowed-inside-job.ts": 0,
+	"noqa-justified.ts": 0,
+	"noqa-bare.ts": 1,
+	"non-status-update.ts": 0,
+};
+
+function runSelfTest() {
+	const fixturesDir = join(REPO_ROOT, "scripts", "fixtures", "int9");
+	let pass = 0;
+	let total = 0;
+	const failures = [];
+
+	for (const [name, expected] of Object.entries(SELF_TEST_EXPECTED)) {
+		total += 1;
+		const abs = join(fixturesDir, name);
+		let violations;
+		try {
+			const text = readFileSync(abs, "utf-8");
+			violations = scanFile(name, text);
+		} catch (err) {
+			failures.push(
+				`${name}: ציפינו ${expected} הפרות, אבל הסריקה זרקה שגיאה: ${String(err)}`,
+			);
+			continue;
+		}
+		if (violations.length === expected) {
+			pass += 1;
+		} else {
+			failures.push(
+				`${name}: ציפינו ${expected} הפרות, התקבלו ${violations.length}` +
+					(violations.length
+						? `:\n${violations.map((v) => `      - ${v.file}:${v.line}: ${v.message}`).join("\n")}`
+						: ""),
+			);
+		}
+	}
+
+	if (failures.length > 0) {
+		process.stderr.write("✗ INV-INT9 self-test נכשל:\n\n");
+		for (const f of failures) process.stderr.write(`  • ${f}\n`);
+		return 1;
+	}
+	process.stdout.write(
+		`✓ INV-INT9 self-test: ${pass}/${total} פיקסצ'רים תואמים לציפייה.\n`,
+	);
+	return 0;
+}
+
+// ---------------------------------------------------------------------
+// Entry point
+// ---------------------------------------------------------------------
+
+function main(argv) {
+	if (argv.includes("--self-test")) {
+		return runSelfTest();
+	}
+	const pathArgs = argv.filter((a) => !a.startsWith("--"));
+	const files =
+		pathArgs.length > 0 ? collectFromArgs(pathArgs) : collectDefault();
+	let violations;
+	try {
+		violations = runGate(files);
+	} catch (err) {
+		process.stderr.write(`✗ INV-INT9 gate — ${String(err.message ?? err)}\n`);
+		return 1;
+	}
+	return reportGate(violations, files.length);
+}
+
+// `exitCode` ולא `process.exit()` — ‏stdout/stderr אל pipe (וזה בדיוק המצב ב-CI)
+// אסינכרוניים ב-POSIX, ו-`process.exit` היה עלול לקטוע את דוח-ההפרות עצמו.
+process.exitCode = main(process.argv.slice(2));