feat(lint): enforce no-chained-type-assertions (#124119)

scripts/oxlint-boundary-guards.mjs

@@ -1,6 +1,49 @@
 const EXPRESSION_WRAPPER_RE =
   /^(?:ChainExpression|ParenthesizedExpression|TSAsExpression|TSNonNullExpression|TSTypeAssertion)$/;
-const TEST_FILE_SUFFIXES = [".test.ts", ".test-utils.ts", ".test-harness.ts", ".e2e-harness.ts"];
+const BOUNDARY_GUARD_FIXTURE_ROOT = "test/fixtures/oxlint-boundary-guards";
+// Shared test-path policy for guards that intentionally exclude fixture, mock, and harness code.
+const TEST_FILE_SUFFIXES = [
+  ".test.ts",
+  ".test.tsx",
+  ".spec.ts",
+  ".spec.tsx",
+  ".test-utils.ts",
+  ".test-utils.tsx",
+  ".test-harness.ts",
+  ".test-harness.tsx",
+  ".e2e-harness.ts",
+  ".e2e-harness.tsx",
+];
+const TEST_PATH_MARKERS = [
+  "/test/",
+  "/tests/",
+  "__tests__",
+  "/e2e/",
+  "test-helpers",
+  "test-support",
+  "test-fixtures",
+  "test-mocks",
+  "test-utils",
+  "mock-http",
+  "-harness.",
+  ".test-utils.",
+  "/mocks/",
+];
+
+function pathMatchesRoot(repoPath, root) {
+  return repoPath === root || repoPath.startsWith(`${root}/`);
+}
+
+function isSkippedTestPath(repoPath) {
+  if (pathMatchesRoot(repoPath, BOUNDARY_GUARD_FIXTURE_ROOT)) {
+    return false;
+  }
+  const slashPrefixedPath = `/${repoPath}`;
+  return (
+    TEST_FILE_SUFFIXES.some((suffix) => repoPath.endsWith(suffix)) ||
+    TEST_PATH_MARKERS.some((marker) => slashPrefixedPath.includes(marker))
+  );
+}
 
 function unwrapExpression(node) {
   let current = node;
@@ -18,7 +61,7 @@ function restrictedCallRule({ allowedFiles = [], message, objects, property, roo
       const repoPath = filename.startsWith(`${cwd}/`) ? filename.slice(cwd.length + 1) : filename;
       if (
         !filename.endsWith(".ts") ||
-        !roots.some((root) => repoPath === root || repoPath.startsWith(`${root}/`)) ||
+        !roots.some((root) => pathMatchesRoot(repoPath, root)) ||
         TEST_FILE_SUFFIXES.some((suffix) => filename.endsWith(suffix)) ||
         allowedFiles.includes(repoPath)
       ) {
@@ -46,6 +89,86 @@ function restrictedCallRule({ allowedFiles = [], message, objects, property, roo
   };
 }
 
+// Adapted from dmmulroy/anti-slop@446268e5d15baa968eaec669ff65358d36ae6259, MIT.
+function isTypeAssertionExpression(node) {
+  return node.type === "TSAsExpression" || node.type === "TSTypeAssertion";
+}
+
+function isConstAssertion(node) {
+  const { typeAnnotation } = node;
+  return (
+    typeAnnotation.type === "TSTypeReference" &&
+    typeAnnotation.typeName.type === "Identifier" &&
+    typeAnnotation.typeName.name === "const"
+  );
+}
+
+function isOutermostAssertionInChain(node) {
+  let current = node;
+  let parent = node.parent;
+
+  while (parent.type === "ParenthesizedExpression" && parent.expression === current) {
+    current = parent;
+    parent = parent.parent;
+  }
+
+  return !isTypeAssertionExpression(parent) || parent.expression !== current;
+}
+
+function isForbiddenAssertionChain(node) {
+  let assertionCount = 0;
+  let hasNonConstAssertion = false;
+  let current = node;
+
+  while (isTypeAssertionExpression(current)) {
+    assertionCount += 1;
+    hasNonConstAssertion ||= !isConstAssertion(current);
+    current = unwrapExpressionParentheses(current.expression);
+  }
+
+  return assertionCount > 1 && hasNonConstAssertion;
+}
+
+function noChainedTypeAssertionsRule({ excludedRoots = [], roots }) {
+  return {
+    meta: {
+      type: "problem",
+      docs: {
+        description:
+          "Disallow chained TypeScript as and angle-bracket assertions, including parenthesized chains.",
+      },
+      messages: {
+        chained:
+          "This assertion chain discards type evidence. Keep the original precise type, or parse untrusted input at its boundary before narrowing it.",
+      },
+    },
+    create(context) {
+      const filename = context.physicalFilename.replaceAll("\\", "/");
+      const cwd = context.cwd.replaceAll("\\", "/");
+      const repoPath = filename.startsWith(`${cwd}/`) ? filename.slice(cwd.length + 1) : filename;
+      if (
+        !roots.some((root) => pathMatchesRoot(repoPath, root)) ||
+        excludedRoots.some((root) => pathMatchesRoot(repoPath, root)) ||
+        isSkippedTestPath(repoPath)
+      ) {
+        return {};
+      }
+
+      const checkTypeAssertion = (node) => {
+        if (!isOutermostAssertionInChain(node) || !isForbiddenAssertionChain(node)) {
+          return;
+        }
+        context.report({ node, messageId: "chained" });
+      };
+
+      return {
+        TSAsExpression: checkTypeAssertion,
+        TSTypeAssertion: checkTypeAssertion,
+      };
+    },
+  };
+}
+
 // Adapted from dmmulroy/anti-slop, MIT.
 const FUNCTION_BOUNDARY_TYPES = new Set([
   "ArrowFunctionExpression",
@@ -504,5 +627,61 @@ export default {
     "no-widen-then-assert": noWidenThenAssertRule({
       roots: ["src", "extensions", "packages", "ui/src", "test/fixtures/oxlint-boundary-guards"],
     }),
+    "no-chained-type-assertions": noChainedTypeAssertionsRule({
+      roots: ["src", "extensions", "packages", "ui/src", BOUNDARY_GUARD_FIXTURE_ROOT],
+      // Burn-down ledger — shrink only; see PR #124060/#124073/#124079/#124082.
+      excludedRoots: [
+        "extensions/amazon-bedrock-mantle",
+        "extensions/anthropic-vertex",
+        "extensions/browser",
+        "extensions/codex",
+        "extensions/copilot",
+        "extensions/deepinfra",
+        "extensions/diagnostics-otel",
+        "extensions/diagnostics-prometheus",
+        "extensions/discord",
+        "extensions/github-copilot",
+        "extensions/google",
+        "extensions/googlechat",
+        "extensions/imessage",
+        "extensions/line",
+        "extensions/llm-task",
+        "extensions/longcat",
+        "extensions/matrix",
+        "extensions/microsoft-foundry",
+        "extensions/msteams",
+        "extensions/qa-lab",
+        "extensions/reef",
+        "extensions/signal",
+        "extensions/slack",
+        "extensions/sms",
+        "extensions/synology-chat",
+        "extensions/telegram",
+        "extensions/tlon",
+        "extensions/voice-call",
+        "extensions/whatsapp",
+        "extensions/workboard",
+        "extensions/zalo",
+        "extensions/zalouser",
+        "packages/ai",
+        "src/runtime.ts",
+        "src/acp",
+        "src/agents",
+        "src/channels",
+        "src/commands",
+        "src/config",
+        "src/gateway",
+        "src/infra",
+        "src/media",
+        "src/meeting-bot",
+        "src/plugin-sdk",
+        "src/plugins",
+        "src/process",
+        "src/proxy-capture",
+        "src/shared",
+        "src/trajectory",
+        "ui/src",
+      ],
+    }),
   },
 };

scripts/run-additional-boundary-checks.mts

@@ -62,6 +62,7 @@ export const BOUNDARY_CHECKS = (
     ["lint:tmp:no-raw-channel-fetch", "pnpm", ["run", "lint:tmp:no-raw-channel-fetch"]],
     ["lint:tmp:no-raw-http2-imports", "pnpm", ["run", "lint:tmp:no-raw-http2-imports"]],
     ["lint:agent:ingress-owner", "pnpm", ["run", "lint:agent:ingress-owner"]],
+    ["lint:no-chained-type-assertions", "pnpm", ["run", "lint:no-chained-type-assertions"]],
     ["lint:no-widen-then-assert", "pnpm", ["run", "lint:no-widen-then-assert"]],
     [
       "lint:plugins:no-register-http-handler",