Bridge: Codex Multi-Agent Adapter

This file is a REFERENCE DOCUMENT. Any orchestrating skill reads it via the Read tool and embeds its instructions directly into Task agent prompts. It is not invoked as a standalone skill — it is a reusable set of instructions for Codex review dispatch via MCP server or CLI.

Input schema, output schema, verdict logic, artifact format, and status semantics are defined in bridge-commons/SKILL.md. This file covers Codex-specific connection detection, reasoning level, prompt adaptation, and execution.

Bridge Identity

bridge: codex
model_family: openai/codex
availability: conditional
connection_preference:
  1: native-dispatch # Executor is Codex — use internal multi-agent capability
  2: mcp # Any executor with MCP access — mcp__codex__codex server
  3: cli # Fallback — codex exec
  4: halt # None available — surface advisory, offer setup

native_dispatch:
  detection: "CODEX_SESSION_ID set AND codex features list shows multi_agent enabled"
  reliability: "MEDIUM — env var check + feature verification"
  multi_agent: true # Codex can spawn parallel domain experts internally

---

Step 1: Pre-Flight — Connection Detection

MUST read bridge-commons/tool-discovery.md first to understand the discovery protocol.

Step 1.0: Discover Execution Context

Before checking connection paths, discover what dispatch methods are available in the CURRENT execution context.

Primary detection: Native Codex execution

codex_native:
  signal_1: "CODEX_SESSION_ID environment variable is set"
  signal_2: "codex features list shows multi_agent enabled"
  check: |
    if [ -n "$CODEX_SESSION_ID" ]; then
      codex features list 2>/dev/null | grep -q "multi_agent.*enabled"
    fi
  reliability: MEDIUM (requires both env var AND feature check)

mcp_available:
  signal: "mcp__codex__codex tool is accessible"
  check: "Attempt to list MCP tools or check .mcp.json for codex server"
  reliability: HIGH (actual tool availability)

If running INSIDE Codex with multi-agent enabled:

{
  "executor_type": "codex",
  "native_dispatch": {
    "available": true,
    "multi_agent": true,
    "session_continuity": true
  },
  "mcp_tools": {
    "available": false
  },
  "recommended_dispatch": "native"
}

→ Use native dispatch (Step 3N). This allows Codex to spawn parallel domain experts internally.

If NOT running inside Codex, proceed to Check A.

---

Check A: Native Dispatch?

If the executor is Codex CLI with multi-agent support enabled, this is the preferred path — spawn parallel Codex agents rather than routing through MCP or CLI.

# Check if running inside a Codex execution context
echo ${CODEX_SESSION_ID:+found}

# Check if multi-agent feature is enabled
codex features list 2>/dev/null | grep -q "multi_agent" && echo "enabled"

If in a Codex session AND multi-agent is enabled → use native dispatch (Step 3N).

This is an experimental feature. If multi-agent is not enabled, or the executor is not Codex → proceed to Check B.

---

Check B: MCP Server Configured?

Look for a codex entry in the active MCP configuration:

# Check project-level MCP config
cat .mcp.json 2>/dev/null | python3 -c "import sys,json; d=json.load(sys.stdin); print('found' if 'codex' in d.get('mcpServers',{}) else 'not-found')" 2>/dev/null

# Or check Claude's global MCP settings
cat ~/.claude.json 2>/dev/null | python3 -c "import sys,json; d=json.load(sys.stdin); print('found' if 'codex' in str(d) else 'not-found')" 2>/dev/null

If found → use MCP path (Step 3A). No further pre-flight needed — MCP server handles auth internally.

---

Check C: CLI Available?

which codex

If found → proceed to Check D.

If not found → no connection available — go to Step 2 (Advisory).

---

Check D: Authenticated? (CLI path only)

codex login status

Exit code 0 → authenticated. Other → go to Step 2 (Advisory) with reason: not_authenticated.

---

Check E: Multi-Agent Feature Enabled? (CLI path only — optional)

codex features list

Look for multi_agent marked as enabled.

• If enabled → proceed with parallel multi-agent dispatch (one sub-agent per domain)
• If not enabled → proceed in single-agent mode (one Codex session reviews all domains together)

Multi-agent is a progressive enhancement. Single-agent mode is a valid fallback — do not halt.

Record multi_agent_enabled: true/false in output for caller transparency.

→ Use CLI path (Step 3B).

---

Step 2: Advisory — Halt and Present Options

Do not skip silently. Surface the appropriate message to the user and wait for a choice.

Advisory: MCP Server Not Configured + CLI Not Found

⚠ Codex is not connected. This bridge requires either the Codex MCP server
  or the Codex CLI.

Options:
  [1] Set up MCP server automatically
      I will add the Codex MCP server to .mcp.json so future sessions
      use it without any CLI installation needed.
      Requires: Node.js 18+ and npx available.

  [2] Install the Codex CLI
      Run: npm install -g @openai/codex
      Then re-run this review.

  [3] Skip Codex bridge
      Continue the review without Codex. Other available bridges will run.

  [4] Abort
      Stop the entire review.

What would you like to do? (1/2/3/4)

If user chooses [1] — Auto-setup MCP server:

Write (or merge) into .mcp.json:

{
  "mcpServers": {
    "codex": {
      "command": "npx",
      "args": ["-y", "codex", "mcp-server"]
    }
  }
}

Then verify the server is reachable. If successful → continue with MCP path (Step 3A). If verification fails → tell the user and offer options [2]/[3]/[4] again.

If user chooses [2]: Return status: HALTED, halt_reason: cli_not_installed. Show install command.

If user chooses [3]: Return status: SKIPPED, skip_reason: user_chose_skip.

If user chooses [4]: Return status: ABORTED. Calling orchestrator must stop entire review.

---

Advisory: CLI Found But Not Authenticated

⚠ Codex CLI found but not authenticated.

To log in:
  codex login              # Browser OAuth flow (interactive)
  codex login --device-auth   # Device code flow (headless/CI)

After authenticating, re-run this review.

Or:
  [1] Skip Codex bridge and continue
  [2] Abort the entire review

Return status: HALTED, halt_reason: not_authenticated.

---

Non-Interactive Environments (Automated Pipelines)

If no interactive context is available, return status: HALTED with the full advisory text in halt_message. Never silently skip in a way that hides a configuration gap.

---

Reasoning Level Selection

Evaluate the review context and select the Codex reasoning level before building the prompt. This applies to both MCP and CLI paths.

Decision Signals

Signal	Reasoning Level
Security audit, cryptographic review, financial compliance	xhigh
Multi-component architecture, 3+ CRITICAL findings expected, complex dependency chains	high
Standard code review, single-domain analysis, routine audit	medium

Evaluate in this order:

1. If request explicitly mentions "critical", "security", "cryptographic", "financial", "compliance" → xhigh
2. If scope covers 20+ files OR 3+ domains with HIGH risk signals → high
3. Otherwise → medium

Xhigh Alert (MANDATORY)

When xhigh is selected, alert the user before proceeding:

⚠ Reasoning level: XHIGH
Codex will use maximum reasoning depth for this review.
This increases token usage and may take 2–3× longer than standard.

Continue? (y/n)

If user declines → fall back to high. Return reasoning_level: "high" in output.

Embedding Reasoning Level

MCP path (Step 3A): pass as reasoning parameter CLI path (Step 3B): pass as --config reasoning-effort={level} (config override)

Store selected level in reasoning_level output field.

---

Step 3: Build Domain Prompt

Codex's multi-agent capability means the prompt is addressed to a coordinator, not a single domain expert. This differs from the bridge-commons Agent Prompt Template (which addresses one expert per call). Adapt as follows:

You are a multi-agent code review coordinator. Spawn one agent per domain
below, run them in parallel using your multi-agent capability, wait for all
to complete, then return a consolidated findings JSON.

Review scope: {review_scope}
Context: {context_summary}
Intensity: {intensity}

Domains to analyze (spawn one agent per domain):
{for each domain:
  "- {domain_name}: focus on {focus_areas from domain-registry}"}

Each agent must return outputs using the schema from bridge-commons:
{
  "domain": "...",
  "outputs": [
    {
      "severity": "CRITICAL | HIGH | MEDIUM | LOW | INFO",
      "title": "...",
      "description": "...",
      "evidence": "...",
      "action": "..."
    }
  ]
}

After all agents complete, consolidate all findings and return:
{
  "domains_analyzed": [...],
  "outputs": [...],
  "verdict": "PASS | FAIL | CONCERNS"
}

In single-agent mode, drop the coordinator framing and use the bridge-commons Agent Prompt Template directly, covering all domains in one prompt.

---

Timeout Estimation

Use bridge-commons base timeout table and intensity multiplier. Codex multi-agent adds sub-agent spawn overhead — apply a higher base when multi-agent is enabled:

# When multi_agent_enabled: true — increase base by 50%
# e.g., 5-20 files: 180s → 270s to account for agent spawn latency
# When multi_agent_enabled: false — use bridge-commons base times directly

No separate bridge multiplier otherwise.

---

Step 3A: Execute via MCP Server (Preferred)

Use the codex MCP tool directly. The MCP server runs codex mcp-server and exposes two tools:

Model Selection — Check Latest at Runtime

Before calling either MCP or CLI, determine the current latest Codex model:

# Via CLI — lists available models
codex prompt --models 2>/dev/null | head -5

# If unavailable, omit model field to use server default

Do NOT hardcode a model name. If model discovery fails, omit the model parameter and let the server select its default.

Tool: codex — Start a session

Call: mcp__codex__codex
Parameters:
  prompt:          {constructed_prompt}
  approval-policy: "never"                  # No interactive approval prompts
  sandbox:         {resolved from capability_profile}
  model:           {latest from models list, or omit}
  reasoning:       "{medium|high|xhigh}"    # From Reasoning Level Selection

Resolve the MCP sandbox from bridge-commons:

• inspect profile → choose the non-mutating Codex sandbox
• modify profile → choose the write-capable Codex sandbox allowed by the executor

The bridge contract is capability-driven. Codex sandbox values are runtime details, not the policy itself.

Capture structuredContent.threadId from response for multi-turn use.

Tool: codex-reply — Continue session (if needed)

Call: mcp__codex__codex-reply
Parameters:
  prompt:   "Summarize and consolidate all agent findings into the JSON format specified."
  threadId: {threadId from previous call}

The codex-reply call implements the bridge-commons Post-Analysis Protocol for the MCP path. Use codex-reply for each subsequent round — the thread maintains full Round 1 history, so only inject the context packet:

Call: mcp__codex__codex-reply
Parameters:
  prompt:   "{role-specific Round N prompt from bridge-commons context packet}"
  threadId: {threadId from Round 1}

Run one codex + N codex-reply calls per role, one role at a time or in parallel sessions.

---

Step 3B: Execute via CLI (Fallback)

# Detect latest model first (if CLI supports it)
CODEX_MODEL=$(codex prompt --models 2>/dev/null | awk 'NR==1{print $1}')
MODEL_FLAG=${CODEX_MODEL:+--model $CODEX_MODEL}   # omit flag if empty

timeout {final_timeout} codex exec "{constructed_prompt}" \
  --sandbox {resolved from capability_profile} \
  --ask-for-approval never \
  --json \
  --output-last-message /tmp/codex-bridge-{review_id}.json \
  --ephemeral \
  --skip-git-repo-check \
  $MODEL_FLAG \
  --config reasoning-effort={medium|high|xhigh}

For the Post-Analysis Protocol via CLI, use separate codex exec calls per round — no session continuity. Embed the full previous-round context in each Round N prompt (same stateless pattern as Gemini CLI).

CLI Error Handling

Exit code	Meaning	Action
0	Success	Parse --output-last-message file for findings
124	Timeout (shell)	Return SKIPPED, skip_reason: timeout_after_{n}s
Other	CLI error	Capture stderr, return SKIPPED with error detail
Valid exit, invalid JSON	Parse error	Attempt partial extraction; else SKIPPED

---

Output

See bridge-commons Output Schema. Bridge-specific fields:

{
  "bridge": "codex",
  "capability_profile": "inspect | modify",
  "model_family": "openai/codex",
  "connection_used": "native-dispatch | mcp | cli",
  "multi_agent_enabled": true,
  "reasoning_level": "medium | high | xhigh"
}

Output ID prefix: X (e.g., X001, X002).

---

Notes

• MCP server is preferred — no CLI install needed, auth handled internally, persistent sessions via codex-reply
• Auto-setup option — orchestrator can write .mcp.json to enable MCP server without user installing anything
• codex exec ≠ codex — bare codex opens an interactive session; always use codex exec for programmatic use
• Capability resolution is shared — map inspect | modify from bridge-commons onto the appropriate Codex sandbox at runtime
• HALTED ≠ SKIPPED — HALTED means the user must make a choice before the review can continue
• Model: check latest via codex prompt --models at runtime; omit to use server default — never hardcode a model name
• X-high reasoning requires explicit user confirmation before proceeding — never activate silently
• Reasoning level persists in output (reasoning_level field) for caller transparency
• Timeout base increases when multi-agent is enabled (agent spawn overhead)