fix: mock agent process, React 18/19 types, release version refs

- Add hidden `mock-agent-process` CLI subcommand implementing a stdio
  JSON-RPC echo agent (ported from examples/mock-acp-agent)
- Update write_mock_agent_process_launcher() to exec the new subcommand
  instead of exiting with error
- Update sdks/react to support React 18 and 19 peer dependencies
- Update @types/react to v19 across workspace (pnpm override + inspector)
- Fix RefObject<T | null> compatibility for React 19 useRef() signatures
- Add version reference replacement logic to release update_version.ts
  covering all docs, examples, and code files listed in CLAUDE.md
- Add missing files to CLAUDE.md Install Version References list
  (architecture.mdx, boxlite, modal, computesdk docs and examples)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/release/update_version.ts

@@ -2,6 +2,7 @@ import * as fs from "node:fs/promises";
 import { join } from "node:path";
 import { $ } from "execa";
 import { glob } from "glob";
+import * as semver from "semver";
 import type { ReleaseOpts } from "./main";
 
 function assert(condition: any, message?: string): asserts condition {
@@ -10,13 +11,56 @@ function assert(condition: any, message?: string): asserts condition {
   }
 }
 
+// Files containing version references that need channel/image tag updates.
+// Keep in sync with CLAUDE.md "Install Version References" section.
+const VERSION_REFERENCE_FILES = [
+  "README.md",
+  "docs/acp-http-client.mdx",
+  "docs/cli.mdx",
+  "docs/quickstart.mdx",
+  "docs/sdk-overview.mdx",
+  "docs/react-components.mdx",
+  "docs/session-persistence.mdx",
+  "docs/architecture.mdx",
+  "docs/deploy/local.mdx",
+  "docs/deploy/cloudflare.mdx",
+  "docs/deploy/vercel.mdx",
+  "docs/deploy/daytona.mdx",
+  "docs/deploy/e2b.mdx",
+  "docs/deploy/docker.mdx",
+  "docs/deploy/boxlite.mdx",
+  "docs/deploy/modal.mdx",
+  "docs/deploy/computesdk.mdx",
+  "frontend/packages/website/src/components/GetStarted.tsx",
+  ".claude/commands/post-release-testing.md",
+  "examples/cloudflare/Dockerfile",
+  "examples/boxlite/Dockerfile",
+  "examples/boxlite-python/Dockerfile",
+  "examples/daytona/src/index.ts",
+  "examples/shared/src/docker.ts",
+  "examples/docker/src/index.ts",
+  "examples/e2b/src/index.ts",
+  "examples/vercel/src/index.ts",
+  "sdks/typescript/src/providers/shared.ts",
+  "scripts/release/main.ts",
+  "scripts/release/promote-artifacts.ts",
+  "scripts/release/sdk.ts",
+  "scripts/sandbox-testing/test-sandbox.ts",
+];
+
 export async function updateVersion(opts: ReleaseOpts) {
-  // 1. Update workspace version and internal crate versions in root Cargo.toml
+  // 1. Read current version from Cargo.toml before overwriting
   const cargoTomlPath = join(opts.root, "Cargo.toml");
   let cargoContent = await fs.readFile(cargoTomlPath, "utf-8");
 
+  const oldVersionMatch = cargoContent.match(/\[workspace\.package\]\nversion = "([^"]+)"/);
+  assert(oldVersionMatch, "Could not find workspace.package version in Cargo.toml");
+  const oldVersion = oldVersionMatch[1];
+  const oldParsed = semver.parse(oldVersion);
+  assert(oldParsed, `Could not parse old version: ${oldVersion}`);
+  const oldMinorChannel = `${oldParsed.major}.${oldParsed.minor}.x`;
+
   // Update [workspace.package] version
-  assert(/\[workspace\.package\]\nversion = ".*"/.test(cargoContent), "Could not find workspace.package version in Cargo.toml");
   cargoContent = cargoContent.replace(/\[workspace\.package\]\nversion = ".*"/, `[workspace.package]\nversion = "${opts.version}"`);
 
   // Discover internal crates from [workspace.dependencies] by matching
@@ -69,4 +113,70 @@ export async function updateVersion(opts: ReleaseOpts) {
     await fs.writeFile(fullPath, updated);
     await $({ cwd: opts.root })`git add ${relPath}`;
   }
+
+  // 3. Update version references across docs, examples, and code
+  await updateVersionReferences(opts, oldVersion, oldMinorChannel);
+}
+
+async function updateVersionReferences(opts: ReleaseOpts, oldVersion: string, oldMinorChannel: string) {
+  const newMinorChannel = opts.minorVersionChannel;
+
+  // Find old Docker image tags by scanning for rivetdev/sandbox-agent:<version>-full patterns
+  // The old version might be a different patch or RC, so we match any version-full tag
+  const oldDockerTagPattern = /rivetdev\/sandbox-agent:([0-9]+\.[0-9]+\.[0-9]+(?:-[a-zA-Z0-9.]+)?)-full/;
+
+  console.log(`\nUpdating version references:`);
+  console.log(`  Old minor channel: ${oldMinorChannel}`);
+  console.log(`  New minor channel: ${newMinorChannel}`);
+  console.log(`  New Docker tag: ${opts.version}-full`);
+
+  const modifiedFiles: string[] = [];
+
+  for (const relPath of VERSION_REFERENCE_FILES) {
+    const fullPath = join(opts.root, relPath);
+
+    let content: string;
+    try {
+      content = await fs.readFile(fullPath, "utf-8");
+    } catch (err: any) {
+      if (err.code === "ENOENT") {
+        console.log(`  ⚠️  Skipping ${relPath} (file not found)`);
+        continue;
+      }
+      throw err;
+    }
+
+    const original = content;
+
+    // Replace minor channel references (e.g. sandbox-agent@0.3.x -> sandbox-agent@0.4.x)
+    content = content.replaceAll(`sandbox-agent@${oldMinorChannel}`, `sandbox-agent@${newMinorChannel}`);
+    content = content.replaceAll(`@sandbox-agent/cli@${oldMinorChannel}`, `@sandbox-agent/cli@${newMinorChannel}`);
+    content = content.replaceAll(`@sandbox-agent/react@${oldMinorChannel}`, `@sandbox-agent/react@${newMinorChannel}`);
+
+    // Replace install script URL channel
+    content = content.replaceAll(`releases.rivet.dev/sandbox-agent/${oldMinorChannel}/`, `releases.rivet.dev/sandbox-agent/${newMinorChannel}/`);
+
+    // Replace Docker image tags (rivetdev/sandbox-agent:<anything>-full -> rivetdev/sandbox-agent:<version>-full)
+    content = content.replaceAll(
+      new RegExp(`rivetdev/sandbox-agent:[0-9]+\\.[0-9]+\\.[0-9]+(?:-[a-zA-Z0-9.]+)?-full`, "g"),
+      `rivetdev/sandbox-agent:${opts.version}-full`,
+    );
+
+    // Replace standalone version-full references in prose (e.g. "The `0.3.2-full` tag pins...")
+    // Match backtick-wrapped version-full patterns
+    content = content.replaceAll(new RegExp("`[0-9]+\\.[0-9]+\\.[0-9]+(?:-[a-zA-Z0-9.]+)?-full`", "g"), `\`${opts.version}-full\``);
+
+    if (content !== original) {
+      await fs.writeFile(fullPath, content);
+      modifiedFiles.push(relPath);
+      console.log(`  ✅ ${relPath}`);
+    }
+  }
+
+  if (modifiedFiles.length > 0) {
+    await $({ cwd: opts.root })`git add ${modifiedFiles}`;
+    console.log(`\nUpdated ${modifiedFiles.length} files with version references.`);
+  } else {
+    console.log(`\nNo version reference files needed updates.`);
+  }
 }