refactor: validate JSON at every parse boundary

Ten sites cast or implicitly typed JSON.parse output; JSON.parse("null")
would have satisfied all of them. parseJson returns a Result and validates
against a typebox schema. js.ts keeps unknown — user script output has no
fixed shape. daemon/bridge.ts assigned JSON.parse straight to CdpRawMessage
with no guard at all; it now uses isCdpRawMessage like the transport does.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

3 files changed, 74 insertions, 46 deletions

diff --git a/src/profile/browser-process.ts b/src/profile/browser-process.ts
index ac31d4d..5eb9b58 100644
--- a/src/profile/browser-process.ts
+++ b/src/profile/browser-process.ts
@@ -34,6 +34,9 @@ import { execFile } from "node:child_process";
 import { access, readFile, readlink } from "node:fs/promises";
 import { join } from "node:path";
 import { promisify } from "node:util";
+import { Type } from "typebox";
+import { Compile } from "typebox/compile";
+import { parseJson } from "../schemas/parse";
 import { browserNameForUserDataDir } from "./paths";
 
 // execFile, not exec: arguments are passed as an array, with no shell involved.
@@ -275,7 +278,17 @@ const POWERSHELL_QUERY = [
   "| ConvertTo-Json -Compress",
 ].join(" ");
 
-type WinProcess = { ExecutablePath?: string | null; CommandLine?: string | null };
+const WinProcessSchema = Type.Object(
+  {
+    ExecutablePath: Type.Optional(Type.Union([Type.String(), Type.Null()])),
+    CommandLine: Type.Optional(Type.Union([Type.String(), Type.Null()])),
+  },
+  { additionalProperties: true },
+);
+
+const WinProcessesSchema = Type.Union([WinProcessSchema, Type.Array(WinProcessSchema)]);
+
+const winProcessesValidator = Compile(WinProcessesSchema);
 
 const collectWin32 = async (): Promise<ReadonlyArray<BrowserCandidate>> => {
   try {
@@ -286,19 +299,20 @@ const collectWin32 = async (): Promise<ReadonlyArray<BrowserCandidate>> => {
     );
     const trimmed = stdout.trim();
     if (trimmed) {
-      const parsed: unknown = JSON.parse(trimmed);
-      // ConvertTo-Json emits an object for a single row, an array for many.
-      const rows: WinProcess[] = Array.isArray(parsed) ? (parsed as WinProcess[]) : [parsed as WinProcess];
-      const candidates = rows
-        .filter((row) => !hasChildProcessType(row.CommandLine ?? ""))
-        .map((row): BrowserCandidate => {
-          const explicit = parseUserDataDirFlag(row.CommandLine ?? "");
-          return {
-            ...(row.ExecutablePath ? { exePath: row.ExecutablePath } : {}),
-            ...(explicit ? { explicitUserDataDir: explicit } : {}),
-          };
-        });
-      if (candidates.length > 0) return candidates;
+      const parsed = parseJson(trimmed, winProcessesValidator);
+      if (parsed.success) {
+        const rows = Array.isArray(parsed.data) ? parsed.data : [parsed.data];
+        const candidates = rows
+          .filter((row) => !hasChildProcessType(row.CommandLine ?? ""))
+          .map((row): BrowserCandidate => {
+            const explicit = parseUserDataDirFlag(row.CommandLine ?? "");
+            return {
+              ...(row.ExecutablePath ? { exePath: row.ExecutablePath } : {}),
+              ...(explicit ? { explicitUserDataDir: explicit } : {}),
+            };
+          });
+        if (candidates.length > 0) return candidates;
+      }
     }
   } catch {
     // PowerShell missing or blocked by policy — fall through to tasklist.
diff --git a/src/profile/list.ts b/src/profile/list.ts
index 5a83654..3915a98 100644
--- a/src/profile/list.ts
+++ b/src/profile/list.ts
@@ -21,6 +21,9 @@
 
 import { readdir, readFile } from "node:fs/promises";
 import { join } from "node:path";
+import { Type } from "typebox";
+import { Compile } from "typebox/compile";
+import { parseJson } from "../schemas/parse";
 
 export type BrowserProfile = {
   /** Profile subdirectory name, e.g. "Default" or "Profile 1". */
@@ -48,21 +51,23 @@ const NON_PROFILE_DIRS: ReadonlySet<string> = new Set([
 export const formatProfileLabel = (name: string, email: string | undefined, dir: string): string =>
   `${name} (${email && email.length > 0 ? email : dir})`;
 
+const JsonObject = Type.Record(Type.String(), Type.Unknown());
+
+const jsonObjectValidator = Compile(JsonObject);
+
 const readJsonFile = async (path: string): Promise<Record<string, unknown> | null> => {
+  let raw: string;
   try {
-    const raw = await readFile(path, "utf8");
-    const parsed: unknown = JSON.parse(raw);
-    if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) return null;
-    return parsed as Record<string, unknown>;
+    raw = await readFile(path, "utf8");
   } catch {
-    // Missing file, permission error, or malformed JSON — the caller falls
-    // back to the next tier, and ultimately to an empty list.
     return null;
   }
+  const parsed = parseJson(raw, jsonObjectValidator);
+  return parsed.success ? parsed.data : null;
 };
 
 const asRecord = (v: unknown): Record<string, unknown> | null =>
-  typeof v === "object" && v !== null && !Array.isArray(v) ? (v as Record<string, unknown>) : null;
+  jsonObjectValidator.Check(v) ? v : null;
 
 const asString = (v: unknown): string | undefined =>
   typeof v === "string" && v.length > 0 ? v : undefined;
diff --git a/src/profile/store.ts b/src/profile/store.ts
index c8b8952..e38ff2e 100644
--- a/src/profile/store.ts
+++ b/src/profile/store.ts
@@ -18,6 +18,9 @@
 import { mkdir, readFile, rename, unlink, writeFile } from "node:fs/promises";
 import { randomUUID } from "node:crypto";
 import { dirname } from "node:path";
+import { Type } from "typebox";
+import { Compile } from "typebox/compile";
+import { parseJson } from "../schemas/parse";
 import { type Result, err, ok } from "../util/result";
 import { pinFilePath } from "./paths";
 
@@ -39,22 +42,26 @@ type PinFile = {
 
 const CURRENT_VERSION = 1;
 
-const parsePin = (value: unknown): ProfilePin | null => {
-  if (typeof value !== "object" || value === null || Array.isArray(value)) return null;
-  const o = value as Record<string, unknown>;
-  const userDataDir = o["userDataDir"];
-  const profileDir = o["profileDir"];
-  const label = o["label"];
-  const savedAt = o["savedAt"];
-  if (typeof userDataDir !== "string" || userDataDir.length === 0) return null;
-  if (typeof profileDir !== "string" || profileDir.length === 0) return null;
-  return {
-    userDataDir,
-    profileDir,
-    label: typeof label === "string" && label.length > 0 ? label : profileDir,
-    savedAt: typeof savedAt === "string" ? savedAt : "",
-  };
-};
+const PinFileSchema = Type.Object(
+  {
+    version: Type.Literal(CURRENT_VERSION),
+    profile: Type.Union([
+      Type.Object(
+        {
+          userDataDir: Type.String({ minLength: 1 }),
+          profileDir: Type.String({ minLength: 1 }),
+          label: Type.Optional(Type.Unknown()),
+          savedAt: Type.Optional(Type.Unknown()),
+        },
+        { additionalProperties: true },
+      ),
+      Type.Null(),
+    ]),
+  },
+  { additionalProperties: true },
+);
+
+const pinFileValidator = Compile(PinFileSchema);
 
 /**
  * The persisted pin, or null when nothing is pinned, the file is missing, or
@@ -68,15 +75,17 @@ export const readPin = async (): Promise<ProfilePin | null> => {
   } catch {
     return null;
   }
-  try {
-    const parsed: unknown = JSON.parse(raw);
-    if (typeof parsed !== "object" || parsed === null) return null;
-    const file = parsed as Record<string, unknown>;
-    if (file["version"] !== CURRENT_VERSION) return null;
-    return parsePin(file["profile"]);
-  } catch {
-    return null;
-  }
+  const parsed = parseJson(raw, pinFileValidator);
+  if (!parsed.success) return null;
+  const profile = parsed.data.profile;
+  if (profile === null) return null;
+  const { userDataDir, profileDir, label, savedAt } = profile;
+  return {
+    userDataDir,
+    profileDir,
+    label: typeof label === "string" && label.length > 0 ? label : profileDir,
+    savedAt: typeof savedAt === "string" ? savedAt : "",
+  };
 };
 
 /**