fix(mcp): emit portable Unicode NUL patterns (#1230)

Preserve NUL rejection while avoiding the short escape rejected by strict
schema consumers. Guard the entire advertised input/output catalog and all
three JavaScript regexp modes.

Assisted-by: Kogasa (gensokyo-skills:kogasa-surprise-testing)

src/contracts/native/nativeToolContracts.ts

@@ -71,7 +71,7 @@ export const swiftSymbolsSchema = z
       .string()
       .min(1)
       .regex(/^[^\n]*$/u, "Each Swift symbol must be one line.")
-      .regex(/^[^\0]*$/u, "Swift symbols cannot contain NUL."),
+      .regex(/^[^\u0000]*$/u, "Swift symbols cannot contain NUL."),
   )
   .min(1);
 

src/domain/apple/dylibResolution.ts

@@ -21,7 +21,7 @@ import {
 
 /** Normalized path below the analyzed root: no `.`/`..` or empty segments. */
 const ROOT_RELATIVE_PATH =
-  /^(?!\/)(?!(?:.*\/)?\.{1,2}(?:\/|$))(?!.*\/\/)(?!.*\/$)[^\\\0]+$/u;
+  /^(?!\/)(?!(?:.*\/)?\.{1,2}(?:\/|$))(?!.*\/\/)(?!.*\/$)[^\\\u0000]+$/u;
 const rootRelativePathSchema = z
   .string()
   .min(1)

src/domain/javascript/electronActiveObservation.ts

@@ -78,7 +78,9 @@ export const electronActiveObservationInputSchema = z.strictObject({
     ),
   args: z
     .array(
-      z.string().regex(/^[^\0]*$/u, "Electron arguments must not contain NUL"),
+      z
+        .string()
+        .regex(/^[^\u0000]*$/u, "Electron arguments must not contain NUL"),
     )
     .default([]),
   actions: z.array(actionSchema).default([]),

src/domain/localPath.ts

@@ -5,7 +5,7 @@ import { z } from "zod";
 export const localPathStringSchema = z
   .string()
   .min(1)
-  .regex(/^[^\0]*$/u, "Local filesystem paths cannot contain NUL");
+  .regex(/^[^\u0000]*$/u, "Local filesystem paths cannot contain NUL");
 
 /** True when the value is an absolute filesystem path on the host platform. */
 export const isAbsoluteLocalPath = (value: string): boolean =>

src/domain/native/nativeCallObservation.ts

@@ -5,7 +5,7 @@ const hexSchema = z.string().regex(/^0x[0-9a-f]+$/u);
 const nativeString = z
   .string()
   .regex(
-    /^[^\0]*$/u,
+    /^[^\u0000]*$/u,
     "Native launch and breakpoint strings cannot contain NUL",
   );
 /** Objective-C class names and selectors never contain spaces or brackets. */
@@ -61,8 +61,10 @@ export const nativeCallObservationInputSchema = z.strictObject({
       z
         .string()
         .min(1)
-        .regex(/^[^=\0]+$/u, "Environment names cannot contain '=' or NUL"),
-      z.string().regex(/^[^\0]*$/u, "Environment values cannot contain NUL"),
+        .regex(/^[^=\u0000]+$/u, "Environment names cannot contain '=' or NUL"),
+      z
+        .string()
+        .regex(/^[^\u0000]*$/u, "Environment values cannot contain NUL"),
     )
     .default({})
     .describe("Overrides on top of the environment REA runs with."),

src/domain/process/processScenario.ts

@@ -8,7 +8,7 @@ const reservedRunIdEnvironmentName = "REA_PROCESS_RUN_ID";
 const environmentName = z
   .string()
   .min(1, "Environment names must not be empty")
-  .regex(/^(?!REA_PROCESS_RUN_ID(?![\s\S]))[^=\0]+$/u, {
+  .regex(/^(?!REA_PROCESS_RUN_ID(?![\s\S]))[^=\u0000]+$/u, {
     error: (issue) =>
       issue.input === reservedRunIdEnvironmentName
         ? `${reservedRunIdEnvironmentName} is reserved by the process adapter`
@@ -17,7 +17,7 @@ const environmentName = z
 const childProcessString = z
   .string()
   .regex(
-    /^[^\0]*$/u,
+    /^[^\u0000]*$/u,
     "Values passed to operating-system APIs cannot contain NUL",
   );
 export const normalizationSchema = z.object({

tests/boundary/mcp/advertisedPatternsVMode.test.ts

@@ -30,7 +30,7 @@ const collectPatterns = (
   }
 };
 
-it("advertises patterns that compile under every engine a client may use", async () => {
+it("advertises portable NUL escapes and patterns that compile in all JS modes", async () => {
   const session = createTestBinarySession(() => {
     throw new Error("No deep provider may start for a schema projection");
   });
@@ -63,15 +63,24 @@ it("advertises patterns that compile under every engine a client may use", async
   // class, so REA's own schema validation cannot observe the defect. `v` mode
   // rejects them, and a client that compiles advertised patterns rejects the
   // complete tools request rather than the affected call.
-  const uncompilable = patterns.flatMap((entry) => {
-    try {
-      new RegExp(entry.pattern, "v");
-      return [];
-    } catch (cause: unknown) {
-      return [
-        `${entry.tool} ${entry.where} ${entry.pattern}: ${cause instanceof Error ? cause.message : String(cause)}`,
-      ];
-    }
-  });
+  const uncompilable = patterns.flatMap((entry) =>
+    ["", "u", "v"].flatMap((flags) => {
+      try {
+        new RegExp(entry.pattern, flags);
+        return [];
+      } catch (cause: unknown) {
+        return [
+          `${entry.tool} ${entry.where} /${entry.pattern}/${flags}: ${cause instanceof Error ? cause.message : String(cause)}`,
+        ];
+      }
+    }),
+  );
   expect(uncompilable).toEqual([]);
+
+  // DeepSeek rejects the short NUL escape even though V8 accepts it in all
+  // three modes. Schema compilation must not hide that interchange failure.
+  expect(patterns.filter(({ pattern }) => pattern.includes("\\0"))).toEqual([]);
+  expect(patterns.some(({ pattern }) => pattern.includes("\\u0000"))).toBe(
+    true,
+  );
 });