Stabilize paired reviewer recovery and owner follow-up

runners/agent-runner/src/reviewer-runtime.ts

@@ -5,6 +5,8 @@ import path from 'path';
 
 import type { RoomRoleContext } from './room-role-context.js';
 
+export type ClaudeReadonlySandboxMode = 'strict' | 'best-effort';
+
 const BLOCKED_GIT_SUBCOMMANDS = new Set([
   'add',
   'am',
@@ -40,6 +42,89 @@ export function isReviewerRuntime(
   return roomRoleContext?.role === 'reviewer';
 }
 
+export function isClaudeReadonlyReviewerRuntime(
+  roomRoleContext?: RoomRoleContext,
+): boolean {
+  return (
+    process.env.EJCLAW_UNSAFE_HOST_PAIRED_MODE === '1' &&
+    process.env.EJCLAW_CLAUDE_REVIEWER_READONLY === '1' &&
+    roomRoleContext?.role === 'reviewer'
+  );
+}
+
+let cachedLinuxBubblewrapReadonlyCapability: boolean | undefined;
+
+function commandExistsForRuntime(command: string): boolean {
+  try {
+    execFileSync('bash', ['-lc', `command -v ${command}`], {
+      stdio: ['ignore', 'ignore', 'ignore'],
+    });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export function canUseLinuxBubblewrapReadonlySandbox(): boolean {
+  if (cachedLinuxBubblewrapReadonlyCapability != null) {
+    return cachedLinuxBubblewrapReadonlyCapability;
+  }
+  if (os.platform() !== 'linux') {
+    cachedLinuxBubblewrapReadonlyCapability = false;
+    return false;
+  }
+  if (!commandExistsForRuntime('bwrap')) {
+    cachedLinuxBubblewrapReadonlyCapability = false;
+    return false;
+  }
+
+  try {
+    execFileSync('bwrap', ['--ro-bind', '/', '/', '/bin/true'], {
+      stdio: ['ignore', 'ignore', 'ignore'],
+    });
+    cachedLinuxBubblewrapReadonlyCapability = true;
+  } catch {
+    cachedLinuxBubblewrapReadonlyCapability = false;
+  }
+
+  return cachedLinuxBubblewrapReadonlyCapability;
+}
+
+export function getClaudeReadonlySandboxMode(
+  platform: NodeJS.Platform = os.platform(),
+  linuxCapabilityProbe: () => boolean = canUseLinuxBubblewrapReadonlySandbox,
+): ClaudeReadonlySandboxMode {
+  if (platform === 'linux') {
+    return linuxCapabilityProbe() ? 'strict' : 'best-effort';
+  }
+  return 'best-effort';
+}
+
+export function buildClaudeReadonlySandboxSettings(
+  protectedPaths: string[],
+  platform: NodeJS.Platform = os.platform(),
+  sandboxMode: ClaudeReadonlySandboxMode = getClaudeReadonlySandboxMode(
+    platform,
+  ),
+) {
+  const normalizedPaths = [...new Set(
+    protectedPaths
+      .filter((value): value is string => Boolean(value))
+      .map((value) => path.resolve(value)),
+  )];
+
+  return {
+    enabled: true,
+    failIfUnavailable: sandboxMode === 'strict',
+    autoAllowBashIfSandboxed: true,
+    allowUnsandboxedCommands: false,
+    filesystem:
+      normalizedPaths.length > 0
+        ? { denyWrite: normalizedPaths }
+        : undefined,
+  };
+}
+
 function resolveGitBinary(baseEnv: NodeJS.ProcessEnv): string {
   return execFileSync('bash', ['-lc', 'command -v git'], {
     encoding: 'utf-8',