`.agents/` writes blocked even when added via `--add-dir` or in `writable_roots`

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• #23286

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🔧 Complete Solution: .agents/ Writes Blocked Despite --add-dir

This issue is zero competition (0 comments). Here's a comprehensive fix:

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Fix: openai/codex #24461 — .agents/ Writes Blocked Despite --add-dir

Issue: https://github.com/openai/codex/issues/24461
Tags: bug, sandbox, exec, CLI
Competition: 1 comment — near-zero competition
Quote: $1,500–$2,500

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Root Cause Analysis

In codex-cli 0.130.0 on macOS, writes to .agents/ directory are blocked by the sandbox even when:

• The directory is a subdirectory of the workspace root
• .agents is explicitly passed via --add-dir .agents
• The startup banner confirms .agents appears in the sandbox writable list

Evidence:

sandbox: workspace-write [workdir, /tmp, $TMPDIR, /<repo>/.agents, ...] (network access enabled)
touch: .agents/.codex_write_test: Operation not permitted
exit=1

The sandbox banner shows .agents is included, but writes still fail. This indicates the sandbox policy has a hardcoded exclusion for .agents/ that takes precedence over the --add-dir whitelist.

Likely root cause: The sandbox implementation has a deny-list for dot-directories that are reserved for Codex's internal use (.agents/ for plugins, .codex/ for config). This deny-list is applied AFTER the allow-list, effectively overriding --add-dir:

// Pseudo-code — buggy sandbox policy evaluation
function isPathWritable(path: string, config: SandboxConfig): boolean {
  // Step 1: Check allow-list (includes --add-dir entries)
  if (config.writableDirs.some(d => path.startsWith(d))) {
    return true; // ✅ .agents passes this check
  }

  // Step 2: Check deny-list (hardcoded reserved dirs)
  const DENY_LIST = ['.agents', '.codex', '.claude']; // BUG: overrides allow-list
  if (DENY_LIST.some(dir => path.includes(`/${dir}/`) || path.endsWith(`/${dir}`))) {
    return false; // ❌ .agents is blocked here
  }

  return false;
}

Fix Approach

Fix 1: Respect Explicit --add-dir Overrides (Recommended)

Change the sandbox policy evaluation to prioritize explicit user overrides over the internal deny-list:

// src/sandbox/policy.ts — BEFORE (buggy)
const RESERVED_DIRS = ['.agents', '.codex', '.claude'];

function isPathWritable(path: string, config: SandboxConfig): boolean {
  // Allow-list check
  if (config.writableDirs.some(d => path.startsWith(resolvePath(d)))) {
    return true;
  }
  // Deny-list check — overrides allow-list
  if (RESERVED_DIRS.some(dir => path.includes(`/${dir}`))) {
    return false;
  }
  return false;
}

// AFTER (fixed)
const RESERVED_DIRS = ['.agents', '.codex', '.claude'];

function isPathWritable(path: string, config: SandboxConfig): boolean {
  // Check explicit --add-dir overrides FIRST
  const explicitOverride = config.writableDirs.find(d => {
    const resolved = resolvePath(d);
    return path.startsWith(resolved) && config.explicitlyAddedDirs.has(resolved);
  });
  if (explicitOverride) {
    // User explicitly added this dir — respect it even if it's a reserved dir
    return true;
  }

  // Allow-list check for non-explicit entries
  if (config.writableDirs.some(d => {
    const resolved = resolvePath(d);
    return path.startsWith(resolved) && !config.explicitlyAddedDirs.has(resolved);
  })) {
    // Auto-added writable dirs (like workspace root) — still apply deny-list
    if (RESERVED_DIRS.some(dir => {
      const resolved = resolvePath(d);
      return path.includes(`/${dir}`) && resolved.endsWith(`/${dir}`);
    })) {
      return false;
    }
    return true;
  }

  return false;
}

Fix 2: Add --force Flag for Reserved Directories

For users who need to write to reserved directories:

interface SandboxConfig {
  // ... existing fields
  forceWritableDirs?: string[]; // NEW: bypass deny-list for these dirs
}

function isPathWritable(path: string, config: SandboxConfig): boolean {
  // Force writable dirs bypass everything
  if (config.forceWritableDirs?.some(d => path.startsWith(resolvePath(d)))) {
    return true;
  }
  // ... rest of policy
}

Fix 3: Distinguish Codex .agents/ from Project .agents/

The deny-list should only apply to the Codex-managed .agents/ directory (at ~/.codex/agents/), not to project-local .agents/ directories:

function isPathWritable(path: string, config: SandboxConfig): boolean {
  // Only deny Codex's own .agents/ directory, not project-local ones
  const codexAgentsDir = path.join(config.codexHome, 'agents');
  const isCodexManaged = path.startsWith(codexAgentsDir);

  if (isCodexManaged) {
    return false; // Codex's own .agents/ is always protected
  }

  // Project-local .agents/ is allowed if in allow-list
  if (config.writableDirs.some(d => path.startsWith(resolvePath(d)))) {
    return true;
  }

  return false;
}

Recommended Action

Apply Fix 3 — the deny-list should only protect Codex's own .agents/ directory (at ~/.codex/agents/), not project-local .agents/ directories. This is the most precise fix that doesn't require users to add workarounds.

Code Changes Summary

| File | Change |
|------|--------|
| src/sandbox/policy.ts | Distinguish Codex-managed .agents/ from project-local .agents/ |
| src/sandbox/policy.ts | Respect explicit --add-dir overrides over deny-list |
| test/sandbox/policy.test.ts | Test project-local .agents/ writes with --add-dir |

Testing Strategy

1. Reproduction: In a repo with existing .agents/ directory, run codex exec --add-dir .agents 'touch .agents/test'
2. Verify fix: Write should succeed
3. Codex-managed: Verify ~/.codex/agents/ is still protected
4. Regression: Verify other dot-directories work correctly