diff --git a/src/commands/artifacts-command.ts b/src/commands/artifacts-command.ts
index dfbd24a..d60c29c 100644
--- a/src/commands/artifacts-command.ts
+++ b/src/commands/artifacts-command.ts
@@ -30,6 +30,7 @@ import {
   parseCommanderProgram,
 } from "./commander-utils.js";
 import { setStderrDevLogStorageRootDirectory } from "../runtime/stderr-dev-log.js";
+import { parseNonNegativeInt } from "./option-parsers.js";
 
 interface WriteTarget {
   write(chunk: string): unknown;
@@ -391,14 +392,6 @@ function parseHarnessKindOption(value: string): AgentHarnessKind {
   );
 }
 
-function parseNonNegativeInt(value: string): number {
-  const parsed = Number.parseInt(value, 10);
-  if (!Number.isFinite(parsed) || parsed < 0) {
-    throw new InvalidArgumentError("value must be a non-negative integer");
-  }
-  return parsed;
-}
-
 function writeJson(stdout: WriteTarget, value: unknown): void {
   stdout.write(`${JSON.stringify(value, null, 2)}\n`);
 }
diff --git a/src/commands/option-parsers.test.ts b/src/commands/option-parsers.test.ts
index fec3f91..c660576 100644
--- a/src/commands/option-parsers.test.ts
+++ b/src/commands/option-parsers.test.ts
@@ -35,6 +35,12 @@ describe("parsePositiveInt", () => {
   it("throws for non-numeric strings", () => {
     expect(() => parsePositiveInt("abc")).toThrow("positive integer");
   });
+
+  it("rejects partially parsed and unsafe integer inputs", () => {
+    for (const value of ["12px", "1.5", "1e3", "9007199254740992"]) {
+      expect(() => parsePositiveInt(value)).toThrow("positive integer");
+    }
+  });
 });
 
 describe("parseNonNegativeInt", () => {
@@ -45,6 +51,10 @@ describe("parseNonNegativeInt", () => {
   it("throws for negative", () => {
     expect(() => parseNonNegativeInt("-1")).toThrow("non-negative");
   });
+
+  it("rejects partially parsed values", () => {
+    expect(() => parseNonNegativeInt("0items")).toThrow("non-negative");
+  });
 });
 
 describe("parseNumber", () => {
@@ -55,6 +65,12 @@ describe("parseNumber", () => {
   it("throws for non-numeric", () => {
     expect(() => parseNumber("xyz")).toThrow("Expected number");
   });
+
+  it("rejects malformed numeric values", () => {
+    for (const value of ["3.14ms", "1.2.3", "Infinity"]) {
+      expect(() => parseNumber(value)).toThrow("Expected number");
+    }
+  });
 });
 
 describe("parseOperatingMode", () => {
diff --git a/src/commands/option-parsers.ts b/src/commands/option-parsers.ts
index 120f78e..041a97b 100644
--- a/src/commands/option-parsers.ts
+++ b/src/commands/option-parsers.ts
@@ -14,9 +14,28 @@ import { MIN_ANTHROPIC_THINKING_BUDGET_TOKENS } from "../bootstrap/config/defaul
 
 export class InvalidArgumentError extends Error {}
 
+const DECIMAL_INTEGER_PATTERN = /^[+-]?\d+$/u;
+const DECIMAL_NUMBER_PATTERN = /^[+-]?(?:\d+\.?\d*|\.\d+)(?:e[+-]?\d+)?$/iu;
+
+function parseDecimalInteger(value: string): number {
+  const normalized = value.trim();
+  if (!DECIMAL_INTEGER_PATTERN.test(normalized)) {
+    return Number.NaN;
+  }
+  return Number(normalized);
+}
+
+function parseFiniteNumber(value: string): number {
+  const normalized = value.trim();
+  if (!DECIMAL_NUMBER_PATTERN.test(normalized)) {
+    return Number.NaN;
+  }
+  return Number(normalized);
+}
+
 export function parsePositiveInt(value: string): number {
-  const parsed = Number.parseInt(value, 10);
-  if (!Number.isInteger(parsed) || parsed <= 0) {
+  const parsed = parseDecimalInteger(value);
+  if (!Number.isSafeInteger(parsed) || parsed <= 0) {
     throw new Error(`Expected positive integer, got: ${value}`);
   }
   return parsed;
@@ -32,8 +51,8 @@ export function parseOperatingMode(value: string): AgentOperatingMode {
 }
 
 export function parseNonNegativeInt(value: string): number {
-  const parsed = Number.parseInt(value, 10);
-  if (!Number.isInteger(parsed) || parsed < 0) {
+  const parsed = parseDecimalInteger(value);
+  if (!Number.isSafeInteger(parsed) || parsed < 0) {
     throw new Error(`Expected non-negative integer, got: ${value}`);
   }
   return parsed;
@@ -107,7 +126,7 @@ export function parseToolSearchIndexProfile(
 }
 
 export function parseNumber(value: string): number {
-  const parsed = Number.parseFloat(value);
+  const parsed = parseFiniteNumber(value);
   if (!Number.isFinite(parsed)) {
     throw new Error(`Expected number, got: ${value}`);
   }