Coding Agents

Coding Agents — Delegate to AI Coding CLIs

Delegate coding to external autonomous AI coding agent CLIs via Hermes terminal/process tools. This umbrella covers Claude Code (Anthropic), Codex (OpenAI), and OpenCode (provider-agnostic, open-source), plus the Kanban Codex Lane pattern for Hermes Kanban workers.

When to Use Coding Agents

Use any coding agent CLI when:

• Building features, refactoring, or batch fixing issues
• The task requires autonomous file exploration and multi-step reasoning
• You want to run parallel implementation lanes

Do NOT use a coding agent when:

• A small direct edit is faster and safer
• The change touches secrets, credentials, or production order-entry systems
• You need human judgment that can't be captured in a prompt

Shared Prerequisites

All coding agents need:

• A git repository — most refuse to run outside one
• Auth credentials (agent-specific, see sections below)
• pty=true for interactive TUI sessions; print/one-shot mode may not need it

Section 1: Claude Code

Anthropic's autonomous coding agent CLI. v2.x can read files, write code, run shell commands, spawn subagents, and manage git workflows.

Install & Auth

npm install -g @anthropic-ai/claude-code
claude auth login                   # Browser OAuth
claude auth login --console         # API key billing
claude auth login --sso             # Enterprise SSO
claude auth status                  # Verify

Print Mode (PREFERRED for one-shot tasks)

# Non-interactive, exits when done. No PTY needed.
terminal(command="claude -p 'Add error handling to all API calls in src/' --allowedTools 'Read,Edit' --max-turns 10", workdir="/path/to/project", timeout=120)

Key flags: --allowedTools 'Read,Edit', --max-turns N, --max-budget-usd N, --output-format json, --json-schema '{...}', --continue (resume last session), --resume <id> (specific session), --bare (fastest startup, needs ANTHROPIC_API_KEY).

Interactive Mode (via tmux)

terminal(command="tmux new-session -d -s claude-work -x 140 -y 40")
terminal(command="tmux send-keys -t claude-work 'cd /path/to/project && claude' Enter")
# Handle trust dialog
terminal(command="sleep 4 && tmux send-keys -t claude-work Enter")
# Send task
terminal(command="tmux send-keys -t claude-work 'Refactor the auth module' Enter")
# Monitor
terminal(command="sleep 15 && tmux capture-pane -t claude-work -p -S -50")

PR Review

# Quick via print mode
terminal(command="git diff main...feature-branch | claude -p 'Review this diff for bugs, security issues, and style problems.' --max-turns 1", timeout=60)

# Deep via worktree
terminal(command="claude -p 'Review this PR thoroughly' --from-pr 42 --max-turns 10", workdir="/path/to/repo", timeout=120)

Key Pitfalls

• Interactive mode REQUIRES tmux — print mode (-p) skips dialog handling
• --dangerously-skip-permissions defaults to "No, exit" — send Down then Enter to accept
• Session resumption requires same directory
• /compact prevents context degradation above 70% usage

Section 2: Codex (OpenAI)

OpenAI's autonomous coding agent CLI. Good for features, refactoring, and batch issue fixing.

Install & Auth

npm install -g @openai/codex

Auth via OPENAI_API_KEY or Codex CLI OAuth (~/.codex/auth.json). For Hermes-managed OAuth: hermes auth add openai-codex.

Headless Server Auth (OAuth Device Flow)

On headless servers (Hetzner, EC2, DO droplet), hermes auth add openai-codex runs an interactive OAuth device code flow. It does NOT fail; it waits for you:

1. Run the command in a foreground terminal — it prints:
   • URL: https://auth.openai.com/codex/device
   • Code: W04N-ADDSI (6-char alphanumeric, hyphenated)
2. Open that URL in a browser on your local machine and enter the code.
3. The CLI polls for up to 15 minutes. No additional flags needed; --no-browser only suppresses the local-browser-open attempt, it does not change the device flow (and is implicit on headless boxes).

Do NOT run this in background=true — you will never see the URL+code. Use foreground or PTY mode. If you accidentally background it, kill it (process(action='kill', ...)) and retry in foreground. After the credential is stored, verify with hermes auth list.

See references/codex-auth-headless.md for the exact API endpoints and step-by-step flow.

One-Shot Tasks

terminal(command="codex exec 'Add dark mode toggle to settings'", workdir="~/project", pty=true)

Background Mode (Long Tasks)

terminal(command="codex exec --full-auto 'Refactor the auth module'", workdir="~/project", background=true, pty=true)
process(action="poll", session_id="<id>")

Key Flags

Parallel Issue Fixing with Worktrees

terminal(command="git worktree add -b fix/issue-78 /tmp/issue-78 main", workdir="~/project")
terminal(command="codex --yolo exec 'Fix issue #78'", workdir="/tmp/issue-78", background=true, pty=true)

Pitfalls

• Always use pty=true — Codex hangs without a PTY
• Git repo required — use mktemp -d && git init for scratch
• Hermes gateway contexts may need --sandbox danger-full-access due to bubblewrap errors
• Headless Codex auth is a device flow — hermes auth add openai-codex prints a URL+code and polls for 15min. Run it foreground, not background. Share the URL+code with the user to complete in their browser. See references/codex-auth-headless.md.

Section 3: OpenCode

Provider-agnostic, open-source AI coding agent. Supports multiple providers (OpenRouter, Anthropic, OpenAI).

Install & Auth

npm i -g opencode-ai@latest
opencode auth login                   # Interactive auth
opencode auth list                    # Verify providers

One-Shot Tasks

terminal(command="opencode run 'Add retry logic to API calls and update tests'", workdir="~/project")

Attach context: -f config.yaml -f .env.example Show thinking: --thinking Force model: --model openrouter/anthropic/claude-sonnet-4

Interactive Sessions (Background)

terminal(command="opencode", workdir="~/project", background=true, pty=true)
process(action="submit", session_id="<id>", data="Implement OAuth refresh flow")
process(action="log", session_id="<id>")
process(action="write", data="\x03")  # Ctrl+C to exit (NOT /exit)

PR Review

terminal(command="opencode pr 42", workdir="~/project", pty=true)

Pitfalls

• /exit is NOT a valid command — it opens an agent selector. Use Ctrl+C (\x03)
• Enter may need to be pressed twice to submit in TUI
• PATH mismatch can select wrong binary — check with which -a opencode

Section 4: Kanban Codex Lane

Use when a Hermes Kanban worker wants to run Codex as an isolated implementation lane while Hermes keeps ownership of task lifecycle, reconciliation, testing, and handoff.

When to Use the Codex Lane

Use when ALL are true:

• Task has clear acceptance criteria and bounded diff
• Repo can be isolated in a git worktree/branch
• Hermes can run canonical tests independently
• Prompt can state all safety constraints

Do NOT use when:

• Task requires human judgment not in the Kanban body
• Change touches secrets, credentials, or production order-entry
• A small direct edit is safer

Ownership Rules

1. Hermes owns the Kanban lifecycle — Codex never calls kanban_complete, kanban_block, or kanban_create
2. Hermes owns final acceptance — treat Codex commits/diffs as untrusted patches
3. Hermes owns test execution — repeat tests from Hermes after Codex exits
4. Hermes owns safety — reject the lane if boundaries are violated

Required Worktree Pattern

TASK_ID="${HERMES_KANBAN_TASK:-t_manual}"
REPO="/path/to/repo"
BASE="$(git -C "$REPO" rev-parse --abbrev-ref HEAD)"
SAFE_TASK="$(printf '%s' "$TASK_ID" | tr -cd '[:alnum:]_-')"
BRANCH="codex/${SAFE_TASK}/$(date -u +%Y%m%d%H%M%S)"
WORKTREE="/tmp/${SAFE_TASK}-codex-lane"

git -C "$REPO" fetch --all --prune
git -C "$REPO" worktree add -b "$BRANCH" "$WORKTREE" "$BASE"

Prompt Construction

Every Codex lane prompt must include:

• task_id, title, and full Kanban acceptance criteria
• Repo path, worktree path, branch name, allowed file scope
• Explicit statement: "Hermes owns Kanban lifecycle; Codex is an input lane only"
• Prohibited actions list
• Verification commands

Reconciliation Checklist

• git status --short --branch shows only expected files
• git diff --stat reviewed by Hermes
• No secrets, credentials, or unrelated artifacts
• Hermes ran canonical tests independently
• Accepted commits applied to Hermes-owned workspace
• Stuck/killed Codex processes cleaned up

Codex Lane Metadata Schema

{
  "codex_lane": {
    "used": true,
    "mode": "exec | goal | skipped",
    "worktree": "/absolute/path",
    "branch": "codex/t_caa69668/20260508100000",
    "result": "accepted | rejected | partial | timed_out",
    "tests_run": [
      {"command": "pytest tests/", "exit_code": 0, "owner": "hermes"}
    ]
  }
}

Section 5: Shared Patterns

Parallel Task Execution

All three agents support parallel worktree-based execution:

# Create worktrees
git worktree add -b fix/issue-78 /tmp/issue-78 main
git worktree add -b fix/issue-99 /tmp/issue-99 main

# Launch agents in each (use whichever CLI is available)
terminal(command="codex --yolo exec 'Fix issue #78'", workdir="/tmp/issue-78", background=true, pty=true)
terminal(command="opencode run 'Fix issue #99'", workdir="/tmp/issue-99", background=true, pty=true)

PR Review Patterns

Choice Guide

Pitfalls (All Agents)

1. Git repo required — most agents refuse to run outside a git directory
2. Do NOT trust self-report — always inspect the diff, re-run tests independently
3. Isolate untrusted work — use worktrees/branches, never run in shared dirty checkout
4. PTY for TUI — interactive sessions hang without a pseudo-terminal
5. Clean up background processes — kill tmux sessions and remove worktrees when done
6. Scoped prompts prevent accidents — use --allowedTools and explicit file scopes
7. Large diffs are expensive — scope down to specific files/directories when reasonable
8. Check binary resolution — which -a codex / which -a opencode to verify which binary runs