fix(agents): reject invalid goal token budgets (#104534)

* fix(agents): reject invalid goal token budgets

* test(agents): update goal assertion for session accessor

---------

Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/agents/tools/goal-tools.test.ts

@@ -110,6 +110,34 @@ describe("goal tools", () => {
     ).toBeUndefined();
   });
 
+  it.each(["42.9", "1abc", 0])(
+    "rejects invalid token budgets before creating a goal: %s",
+    async (tokenBudget) => {
+      const { config, template } = await createStoreConfig();
+      const tool = createCreateGoalTool({
+        agentSessionKey: "global",
+        runSessionKey: "global",
+        sessionAgentId: "research",
+        config,
+      });
+
+      const storePath = resolveStorePath(template, { agentId: "research" });
+      await upsertSessionEntry({
+        storePath,
+        sessionKey: "global",
+        entry: { sessionId: "sess-global", updatedAt: 1 },
+      });
+      await expect(
+        tool.execute("call-invalid-budget", {
+          objective: "ship global work",
+          token_budget: tokenBudget,
+        }),
+      ).rejects.toThrow("token_budget must be a positive integer");
+
+      expect(getSessionEntry({ storePath, sessionKey: "global" })?.goal).toBeUndefined();
+    },
+  );
+
   it("prefers scoped run session keys over the fallback session agent", async () => {
     const { config, template } = await createStoreConfig();
     const tool = createCreateGoalTool({

src/agents/tools/goal-tools.ts

@@ -18,7 +18,7 @@ import {
   type AnyAgentTool,
   ToolInputError,
   jsonResult,
-  readNumberParam,
+  readPositiveIntegerParam,
   readStringParam,
 } from "./common.js";
 
@@ -40,7 +40,8 @@ const CreateGoalToolSchema = Type.Object({
     description: "Concrete objective to pursue. Create only when explicitly requested.",
   }),
   token_budget: Type.Optional(
-    Type.Number({
+    Type.Integer({
+      minimum: 1,
       description: "Optional positive token budget for this goal.",
     }),
   ),
@@ -103,11 +104,9 @@ export function createCreateGoalTool(options: GoalToolOptions): AnyAgentTool {
     execute: async (_toolCallId, args) => {
       const params = args as Record<string, unknown>;
       const objective = readStringParam(params, "objective", { required: true });
-      const tokenBudget = readNumberParam(params, "token_budget", { integer: true });
-      if (tokenBudget !== undefined && tokenBudget <= 0) {
-        // Budgets are positive limits; zero would immediately make accounting ambiguous.
-        throw new ToolInputError("token_budget must be positive");
-      }
+      const tokenBudget = readPositiveIntegerParam(params, "token_budget", {
+        message: "token_budget must be a positive integer",
+      });
       const scope = resolveGoalSessionScope(options);
       const goal = await createSessionGoal({
         ...scope,