diff --git a/docs/performance-budgets.md b/docs/performance-budgets.md
index 48852e80..228d61c4 100644
--- a/docs/performance-budgets.md
+++ b/docs/performance-budgets.md
@@ -1,4 +1,4 @@
-# Informational route JavaScript budgets
+# Route JavaScript budgets (enforced)
 
 Run after the existing production build; no second build or server is needed:
 
@@ -28,20 +28,22 @@ The definition follows the data exposed by the installed Next 16.3.8 build and t
 
 ## Initial limits
 
-The first limits are **baseline bytes × 1.15, rounded upward to the next 10 KiB (10,240 bytes)** independently for raw and gzip. They are provisional size alerts, not validated speed targets. Baseline: local production build `build-TfctsWXpff2fKS`, Next 16.3.4 **Turbopack**; its source commit was not inferred.
+The limits are **baseline bytes × 1.15, rounded upward to the next 10 KiB (10,240 bytes)** independently for raw and gzip. They are size guardrails, not validated speed targets.
 
-The production build now runs webpack, so the numbers it reports are not directly comparable to the baseline below. Re-measured on the current webpack build the routes land at `/me` 786138/247738, `/news` 781601/245672, `/events` 782011/245923, `/search` 783262/246578, `/admin/catalog` 1172089/370843, `/admin/studio/furni` 1374128/440546 (raw/gzip). All remain inside the limits below, but `/admin/studio/furni` sits at ~98% of its gzip limit, so the next dependency added to that route will trip it. Recalibrate the table and `scripts/performance-budgets.json` together if the intent is to reset the baseline on webpack.
+Baselines were last recalibrated against a local webpack production build (Next 16.4.1, `next build --webpack`) and cross-checked against the report the Docker image build emits: `/me` 621460/195411, `/news` 616712/193199, `/events` 617121/193450, `/search` 618536/194216, `/admin/catalog` 1049094/330369, `/admin/studio/furni` 1397566/447765 (raw/gzip). The earlier Turbopack numbers (previous revision) were **not** comparable and were dropped.
+
+The image build compiles the app, then runs `scripts/performance-report.mjs` in the same `RUN` layer (`Dockerfile:48-53`). In `mode: enforce` a failing route therefore fails the image build, which blocks both the PR `preflight` job and the `deploy` job. Recalibrate the table and `scripts/performance-budgets.json` **together** in the same commit whenever the envelope legitimately grows (new route dependency, Next upgrade).
 
 | Route | Baseline raw bytes | Baseline gzip bytes | Raw limit | Gzip limit |
 | --- | ---: | ---: | ---: | ---: |
-| `/me` | 767156 | 238571 | 890880 | 276480 |
-| `/news` | 765367 | 237599 | 880640 | 276480 |
-| `/events` | 765851 | 237964 | 890880 | 276480 |
-| `/search` | 765851 | 237964 | 890880 | 276480 |
-| `/admin/catalog` | 1654898 | 492619 | 1904640 | 573440 |
-| `/admin/studio/furni` | 1241312 | 391541 | 1433600 | 450560 |
+| `/me` | 621460 | 195411 | 716800 | 225280 |
+| `/news` | 616712 | 193199 | 716800 | 225280 |
+| `/events` | 617121 | 193450 | 716800 | 225280 |
+| `/search` | 618536 | 194216 | 716800 | 225280 |
+| `/admin/catalog` | 1049094 | 330369 | 1208320 | 389120 |
+| `/admin/studio/furni` | 1397566 | 447765 | 1607680 | 522240 |
 
-Configured limits are positive integer bytes; `null` explicitly means observe-only. `scripts/performance-budgets.json` remains `mode: informational`. Exceeding a limit produces `over-budget` and a warning, with exit code 0. Missing production `BUILD_ID`, unsupported manifests, missing routes or missing referenced assets produce `unavailable` with a reason and **no partial/zero total**, also exit code 0. Malformed budget configuration or an unwritable output directory fails the command. This keeps initial CI reporting non-blocking while preventing invalid configuration from quietly disabling limits.
+Configured limits are positive integer bytes; `null` explicitly means observe-only. `scripts/performance-budgets.json` runs `mode: enforce`: an `over-budget` route prints `Performance budgets enforced: <route> (over-budget)` and exits non-zero. Missing production `BUILD_ID`, unsupported manifests, missing routes or missing referenced assets produce `unavailable` with a reason and **no partial/zero total**; under `enforce` an `unavailable` route also fails the command, so a bundler change that breaks measurement cannot pass quietly. Malformed budget configuration or an unwritable output directory always fails the command. Set `mode` back to `informational` only while recalibrating, never as a permanent state.
 
-Synthetic tests cover shared-chunk deduplication, exact byte/gzip calculations, route bootstrap selection, missing data, safe parsing and CLI exit behavior. Run `pnpm exec vitest run --coverage.enabled=false scripts/performance-report.test.mjs`.
+Synthetic tests cover shared-chunk deduplication, exact byte/gzip calculations, route bootstrap selection, missing data, safe parsing and CLI exit behavior in both modes. Run `pnpm exec vitest run --coverage.enabled=false scripts/performance-report.test.mjs`.
 
diff --git a/scripts/performance-budgets.json b/scripts/performance-budgets.json
index b1acf0a9..96e95ebe 100644
--- a/scripts/performance-budgets.json
+++ b/scripts/performance-budgets.json
@@ -1,36 +1,36 @@
 {
 	"schemaVersion": 1,
-	"mode": "informational",
+	"mode": "enforce",
 	"routes": [
 		{
 			"route": "/me",
-			"maxInitialRawBytes": 890880,
-			"maxInitialGzipBytes": 276480
+			"maxInitialRawBytes": 716800,
+			"maxInitialGzipBytes": 225280
 		},
 		{
 			"route": "/news",
-			"maxInitialRawBytes": 880640,
-			"maxInitialGzipBytes": 276480
+			"maxInitialRawBytes": 716800,
+			"maxInitialGzipBytes": 225280
 		},
 		{
 			"route": "/events",
-			"maxInitialRawBytes": 890880,
-			"maxInitialGzipBytes": 276480
+			"maxInitialRawBytes": 716800,
+			"maxInitialGzipBytes": 225280
 		},
 		{
 			"route": "/search",
-			"maxInitialRawBytes": 890880,
-			"maxInitialGzipBytes": 276480
+			"maxInitialRawBytes": 716800,
+			"maxInitialGzipBytes": 225280
 		},
 		{
 			"route": "/admin/catalog",
-			"maxInitialRawBytes": 1904640,
-			"maxInitialGzipBytes": 573440
+			"maxInitialRawBytes": 1208320,
+			"maxInitialGzipBytes": 389120
 		},
 		{
 			"route": "/admin/studio/furni",
-			"maxInitialRawBytes": 1433600,
-			"maxInitialGzipBytes": 450560
+			"maxInitialRawBytes": 1607680,
+			"maxInitialGzipBytes": 522240
 		}
 	]
 }
diff --git a/scripts/performance-report.mjs b/scripts/performance-report.mjs
index 234cfbed..1403085f 100644
--- a/scripts/performance-report.mjs
+++ b/scripts/performance-report.mjs
@@ -7,12 +7,12 @@ const LIMIT_KEYS = ["route", "maxInitialRawBytes", "maxInitialGzipBytes"];
 export function validateBudgets(config) {
 	if (
 		config?.schemaVersion !== 1 ||
-		config.mode !== "informational" ||
+		(config.mode !== "informational" && config.mode !== "enforce") ||
 		!Array.isArray(config.routes) ||
 		config.routes.length === 0
 	)
 		throw new Error(
-			"Budget config requires schemaVersion 1, mode informational and nonempty routes.",
+			"Budget config requires schemaVersion 1, mode informational or enforce, and nonempty routes.",
 		);
 	if (
 		Object.keys(config).some(
@@ -288,7 +288,7 @@ export function collectReport(nextDir, config, metadata = {}) {
 	});
 	return {
 		schemaVersion: 1,
-		mode: "informational",
+		mode: config.mode,
 		generatedAt: new Date().toISOString(),
 		buildId,
 		commitSha: metadata.commitSha ?? null,
@@ -308,6 +308,10 @@ export function collectReport(nextDir, config, metadata = {}) {
 }
 
 export function markdownReport(report) {
+	const modeLine =
+		report.mode === "enforce"
+			? `Build: ${report.buildId ?? "unavailable"}. Declared commit: ${report.commitSha ?? "not supplied"}. Mode: enforce; an over-budget or unavailable route fails the command and the image build.`
+			: `Build: ${report.buildId ?? "unavailable"}. Declared commit: ${report.commitSha ?? "not supplied"}. Mode: informational; exceeded budgets and unavailable metrics do not fail CI.`;
 	const lines = [
 		"# Route JavaScript size report",
 		"",
@@ -315,7 +319,7 @@ export function markdownReport(report) {
 		"",
 		report.gzip,
 		"",
-		`Build: ${report.buildId ?? "unavailable"}. Declared commit: ${report.commitSha ?? "not supplied"}. Mode: informational; exceeded budgets and unavailable metrics do not fail CI.`,
+		modeLine,
 		"",
 		"| Route | State | Unique JS | Raw bytes | Gzip bytes | Raw budget | Gzip budget |",
 		"| --- | --- | ---: | ---: | ---: | ---: | ---: |",
@@ -370,6 +374,17 @@ export function main(argv = process.argv.slice(2)) {
 			console.warn(
 				`Performance warning: ${row.route} ${row.status}${row.reason ? `: ${row.reason}` : ""}`,
 			);
+	if (report.mode === "enforce") {
+		const failed = report.routes.filter((row) => row.status !== "measured");
+		if (failed.length > 0) {
+			console.error(
+				`Performance budgets enforced: ${failed
+					.map((row) => `${row.route} (${row.status})`)
+					.join(", ")}`,
+			);
+			process.exitCode = 1;
+		}
+	}
 	return report;
 }
 if (
diff --git a/scripts/performance-report.test.mjs b/scripts/performance-report.test.mjs
index 92f8adc0..a385ea3f 100644
--- a/scripts/performance-report.test.mjs
+++ b/scripts/performance-report.test.mjs
@@ -373,7 +373,10 @@ describe("route JS measurement", () => {
 		expect(() =>
 			validateBudgets({ ...config, routes: [budget, budget] }),
 		).toThrow();
-		expect(() => validateBudgets({ ...config, mode: "enforce" })).toThrow();
+		expect(validateBudgets({ ...config, mode: "enforce" }).mode).toBe(
+			"enforce",
+		);
+		expect(() => validateBudgets({ ...config, mode: "strict" })).toThrow();
 		expect(() => validateBudgets({ ...config, typo: true })).toThrow();
 	});
 	it("emits warnings and artifacts with exit zero when a build is unavailable", () => {
@@ -423,4 +426,51 @@ describe("route JS measurement", () => {
 		expect(markdown).toContain("not measured browser traffic");
 		expect(markdown).toContain("Raw bytes");
 	});
+	describe("enforce mode", () => {
+		const run = (dir, budgets) => {
+			const write = (relative, value) => {
+				const file = path.join(dir, relative);
+				mkdirSync(path.dirname(file), { recursive: true });
+				writeFileSync(file, JSON.stringify(value));
+			};
+			write("budgets.json", budgets);
+			return spawnSync(
+				process.execPath,
+				[
+					"scripts/performance-report.mjs",
+					"--next-dir",
+					dir,
+					"--config",
+					path.join(dir, "budgets.json"),
+					"--output-dir",
+					path.join(dir, "reports"),
+				],
+				{ encoding: "utf8" },
+			);
+		};
+		it("passes when every route is measured within budget", () => {
+			const enforce = { ...config, mode: "enforce" };
+			const runResult = run(fixture().dir, enforce);
+			expect(runResult.status).toBe(0);
+			expect(runResult.stdout).toContain("Mode: enforce");
+			expect(runResult.stderr).not.toContain("Performance budgets enforced");
+		});
+		it("fails when a route is over budget", () => {
+			const enforce = {
+				schemaVersion: 1,
+				mode: "enforce",
+				routes: [{ ...budget, maxInitialRawBytes: 1, maxInitialGzipBytes: 1 }],
+			};
+			const runResult = run(fixture().dir, enforce);
+			expect(runResult.status).toBe(1);
+			expect(runResult.stderr).toContain("Performance budgets enforced");
+			expect(runResult.stderr).toContain("/news (over-budget)");
+		});
+		it("fails when a route cannot be measured, so broken manifests do not pass quietly", () => {
+			const enforce = { ...config, mode: "enforce" };
+			const runResult = run(path.join(fixture().dir, "missing"), enforce);
+			expect(runResult.status).toBe(1);
+			expect(runResult.stderr).toContain("/news (unavailable)");
+		});
+	});
 });
diff --git a/vitest.config.ts b/vitest.config.ts
index d69edfb2..729fce42 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -38,10 +38,10 @@ export default defineConfig({
 			provider: "v8",
 			reporter: ["text", "lcov", "html"],
 			thresholds: {
-				statements: 12,
-				branches: 9,
-				functions: 10,
-				lines: 13,
+				statements: 36,
+				branches: 29,
+				functions: 30,
+				lines: 37,
 			},
 			include: ["src/**/*.{ts,tsx}"],
 			exclude: [