fix(gemini): preserve pattern in antigravity tool schema sanitizer (#4651)

Integrated into release/v3.8.36 — port (rebuilt from stale base; defining commit cherry-picked clean over release tip, release-green validated)

open-sse/translator/helpers/geminiHelper.ts

@@ -10,7 +10,10 @@ export const GEMINI_UNSUPPORTED_SCHEMA_KEYS = new Set([
   "maxLength",
   "exclusiveMinimum",
   "exclusiveMaximum",
-  "pattern",
+  // NOTE: `pattern` is intentionally NOT in this set. Antigravity (Gemini-derived
+  // surface) accepts `pattern` on string constraints, and glob/grep/file-search
+  // tools depend on it to express their argument regex. Removing it produced
+  // upstream 400s and wrong-tool semantics (decolua/9router#1368).
   "minItems",
   "maxItems",
   "format",

tests/unit/gemini-antigravity-pattern-preserved.test.ts

@@ -0,0 +1,54 @@
+// Regression test: `pattern` must be preserved in antigravity tool schemas.
+//
+// Upstream: decolua/9router @ f6c2f7ca / Fixes decolua/9router#1368.
+//
+// Tools such as glob/grep/file-search rely on a `pattern` constraint on
+// string parameters. Antigravity (Gemini-derived) DOES accept `pattern`,
+// so removing it for that surface drops critical tool semantics and
+// produces upstream 400s / wrong-tool-call behavior.
+//
+// Two assertions, mirroring how the field is consumed downstream:
+//   1) `pattern` must NOT live in the unsupported keyword set used by the
+//      antigravity schema cleaner.
+//   2) End-to-end, `cleanJSONSchemaForAntigravity` must preserve a `pattern`
+//      constraint placed on a string property (typical glob/grep tool).
+
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import {
+  GEMINI_UNSUPPORTED_SCHEMA_KEYS,
+  cleanJSONSchemaForAntigravity,
+} from "../../open-sse/translator/helpers/geminiHelper.ts";
+
+test("GEMINI_UNSUPPORTED_SCHEMA_KEYS does not strip `pattern` for antigravity", () => {
+  assert.equal(
+    GEMINI_UNSUPPORTED_SCHEMA_KEYS.has("pattern"),
+    false,
+    "`pattern` is supported by antigravity and must be preserved on tool schemas"
+  );
+});
+
+test("cleanJSONSchemaForAntigravity preserves `pattern` on glob/grep-style tool schema", () => {
+  const schema = {
+    type: "object",
+    properties: {
+      glob: {
+        type: "string",
+        description: "Glob pattern to match files",
+        pattern: "^[A-Za-z0-9_\\-/*.]+$",
+      },
+    },
+    required: ["glob"],
+  };
+
+  const cleaned = cleanJSONSchemaForAntigravity(schema) as {
+    properties: { glob: { pattern?: string } };
+  };
+
+  assert.equal(
+    cleaned.properties.glob.pattern,
+    "^[A-Za-z0-9_\\-/*.]+$",
+    "`pattern` constraint on a string property must survive antigravity cleaning"
+  );
+});

tests/unit/translator-gemini-schema-pattern-property.test.ts

@@ -41,9 +41,10 @@ test("#1368: a property named 'pattern' survives Gemini schema sanitization", ()
   );
 });
 
-test("#1368: a string-level `pattern` CONSTRAINT is still stripped", () => {
-  // When `pattern` is an actual validation constraint on a string schema node,
-  // Gemini does not support it, so it must still be removed.
+test("#1368: a string-level `pattern` CONSTRAINT is preserved for antigravity", () => {
+  // Antigravity (Gemini-derived) DOES accept `pattern` on string constraints.
+  // Stripping it broke glob/grep/file-search tools that express their argument
+  // regex via `pattern`. The sanitizer must keep it. (Ported from 9router @ f6c2f7ca.)
   const schema = {
     type: "object",
     properties: {
@@ -58,8 +59,8 @@ test("#1368: a string-level `pattern` CONSTRAINT is still stripped", () => {
 
   assert.ok(cleaned.properties.code, "the `code` property itself survives");
   assert.equal(
-    Object.prototype.hasOwnProperty.call(cleaned.properties.code, "pattern"),
-    false,
-    "the string `pattern` constraint must be stripped"
+    (cleaned.properties.code as { pattern?: string }).pattern,
+    "^[A-Z]{3}$",
+    "the string `pattern` constraint must be preserved for antigravity"
   );
 });