fix(core): clarify Code Mode tool boundary (#39540)

packages/core/src/codemode/instructions.ts

@@ -6,7 +6,9 @@ import { Instructions } from "../instructions/index"
 import { CodeModeCatalog } from "./catalog"
 
 // prettier-ignore
-const prompt = (hasMoreTools: boolean) => `The Code Mode tool catalog below is ${hasMoreTools ? "partial" : "complete"}.${hasMoreTools ? `
+const prompt = (hasMoreTools: boolean) => `The Code Mode tool catalog below is ${hasMoreTools ? "partial" : "complete"}.
+
+${hasMoreTools ? "The Code Mode catalog and `search` results are" : "This catalog is"} the complete set of tools available within Code Mode. Tools presented elsewhere are not available in this runtime.${hasMoreTools ? `
 
 ## Search
 

packages/core/src/codemode/tool.ts

@@ -33,7 +33,7 @@ type CollectedFiles = {
 
 // Invariant model-facing guidance; the changing tool catalog is delivered through Instructions.
 const description = [
-  "Run JavaScript to orchestrate tool calls and compose their results through `{ code }` in a confined Code Mode runtime.",
+  "Run JavaScript in a confined Code Mode runtime to orchestrate tool calls and compose their results.",
   "Imports, direct filesystem access, and timers are unavailable. Do not use `fetch`; all external access goes through `tools`.",
   "Within `{ code }`, the only callable tools are those explicitly listed in the Code Mode catalog instructions or returned by `search`. Inside `{ code }`, ignore tools shown outside the Code Mode catalog. They are not available in the Code Mode runtime.",
   'Call tools through `tools` using only exact paths and signatures from the catalog. Do not infer or normalize tool names; preserve bracket notation such as `tools.<namespace>["tool-name"](input)`.',

packages/core/test/codemode/catalog.test.ts

@@ -67,6 +67,7 @@ describe("CodeModeInstructions.render", () => {
     expect(instructions).toContain(`  - ${lookup.signature} // Look up an order by ID`)
     expect(instructions).not.toContain("## Search")
     expect(instructions).toContain("The Code Mode tool catalog below is complete.")
+    expect(instructions).toContain("This catalog is the complete set of tools available within Code Mode.")
     expect(instructions).not.toContain("surrounding top-level agent tools")
   })
 
@@ -76,6 +77,9 @@ describe("CodeModeInstructions.render", () => {
     expect(partial).toContain("- orders (1 tool, none shown)")
     expect(partial).toContain("## Search")
     expect(partial).toContain("The Code Mode tool catalog below is partial.")
+    expect(partial).toContain(
+      "The Code Mode catalog and `search` results are the complete set of tools available within Code Mode.",
+    )
     expect(partial).not.toContain("surrounding top-level agent tools")
     expect(partial).toContain("- search(input: {")
     expect(partial).toContain("  limit?: number,\n  offset?: number,")

packages/core/test/codemode/instructions.test.ts

@@ -44,6 +44,9 @@ describe("CodeModeInstructions", () => {
   it.effect("renders the initial catalog, semantic deltas, and removal", () =>
     Effect.gen(function* () {
       const initialized = yield* readInitial(CodeModeInstructions.make([echo]))
+      expect(initialized.text).toContain(
+        "This catalog is the complete set of tools available within Code Mode. Tools presented elsewhere are not available in this runtime.",
+      )
       expect(initialized.text).toContain("## Available tools")
       expect(initialized.text).not.toContain("## Search")
       expect(initialized.text).toContain(`  - ${echo.signature} // Echo text`)

packages/core/test/tool-execute.test.ts

@@ -22,7 +22,7 @@ const createCodeMode = (tools: ReadonlyMap<string, Info>) =>
 test("execute describes invariant Code Mode behavior", () => {
   expect(createCodeMode(new Map()).description).toBe(
     [
-      "Run JavaScript to orchestrate tool calls and compose their results through `{ code }` in a confined Code Mode runtime.",
+      "Run JavaScript in a confined Code Mode runtime to orchestrate tool calls and compose their results.",
       "Imports, direct filesystem access, and timers are unavailable. Do not use `fetch`; all external access goes through `tools`.",
       "Within `{ code }`, the only callable tools are those explicitly listed in the Code Mode catalog instructions or returned by `search`. Inside `{ code }`, ignore tools shown outside the Code Mode catalog. They are not available in the Code Mode runtime.",
       'Call tools through `tools` using only exact paths and signatures from the catalog. Do not infer or normalize tool names; preserve bracket notation such as `tools.<namespace>["tool-name"](input)`.',