oh-my-opencode/src/hooks/AGENTS.md

HOOKS KNOWLEDGE BASE

OVERVIEW

163 lifecycle hooks intercepting/modifying agent behavior across 5 events.

Event Types:

• UserPromptSubmit (chat.message) - Can block
• PreToolUse (tool.execute.before) - Can block
• PostToolUse (tool.execute.after) - Cannot block
• Stop (event: session.stop) - Cannot block
• onSummarize (Compaction) - Cannot block

STRUCTURE

hooks/
├── agent-usage-reminder/         # Specialized agent hints (212 lines)
├── anthropic-context-window-limit-recovery/ # Auto-summarize on limit (2232 lines)
├── anthropic-effort/             # Anthropic effort level management (272 lines)
├── atlas/                        # Main orchestration hook (1976 lines)
├── auto-slash-command/           # Detects /command patterns (1134 lines)
├── auto-update-checker/          # Plugin update check (1140 lines)
├── background-notification/      # OS notifications (33 lines)
├── category-skill-reminder/      # Reminds of category skills (597 lines)
├── claude-code-hooks/            # settings.json compat - see AGENTS.md (2110 lines)
├── comment-checker/              # Prevents AI slop comments (710 lines)
├── compaction-context-injector/  # Injects context on compaction (128 lines)
├── compaction-todo-preserver/    # Preserves todos during compaction (203 lines)
├── context-window-monitor.ts     # Reminds of headroom (99 lines)
├── delegate-task-retry/          # Retries failed delegations (266 lines)
├── directory-agents-injector/    # Auto-injects AGENTS.md (195 lines)
├── directory-readme-injector/    # Auto-injects README.md (190 lines)
├── edit-error-recovery/          # Recovers from edit failures (188 lines)
├── empty-task-response-detector.ts # Detects empty responses (27 lines)
├── index.ts                      # Hook aggregation + registration (46 lines)
├── interactive-bash-session/     # Tmux session management (695 lines)
├── keyword-detector/             # ultrawork/search/analyze modes (1665 lines)
├── non-interactive-env/          # Non-TTY environment handling (483 lines)
├── preemptive-compaction.ts      # Preemptive context compaction (108 lines)
├── prometheus-md-only/           # Planner read-only mode (955 lines)
├── question-label-truncator/     # Auto-truncates question labels (199 lines)
├── ralph-loop/                   # Self-referential dev loop (1687 lines)
├── rules-injector/               # Conditional rules injection (1604 lines)
├── session-notification.ts       # Session event notifications (108 lines)
├── session-recovery/             # Auto-recovers from crashes (1279 lines)
├── sisyphus-junior-notepad/      # Sisyphus Junior notepad (76 lines)
├── start-work/                   # Sisyphus work session starter (648 lines)
├── stop-continuation-guard/      # Guards stop continuation (214 lines)
├── subagent-question-blocker/    # Blocks subagent questions (112 lines)
├── task-reminder/                # Task progress reminders (210 lines)
├── task-resume-info/             # Resume info for cancelled tasks (39 lines)
├── tasks-todowrite-disabler/     # Disables TodoWrite when tasks active (202 lines)
├── think-mode/                   # Dynamic thinking budget (1365 lines)
├── thinking-block-validator/     # Ensures valid <thinking> blocks (169 lines)
├── todo-continuation-enforcer/   # Force TODO completion (2061 lines)
├── tool-output-truncator.ts      # Prevents context bloat (62 lines)
├── unstable-agent-babysitter/    # Monitors unstable agent behavior (451 lines)
└── write-existing-file-guard/    # Guards against overwriting files (356 lines)

HOOK EVENTS

Event	Timing	Can Block	Use Case
UserPromptSubmit	chat.message	Yes	Keyword detection, slash commands
PreToolUse	tool.execute.before	Yes	Validate/modify inputs, inject context
PostToolUse	tool.execute.after	No	Truncate output, error recovery
Stop	event (session.stop)	No	Auto-continue, notifications
onSummarize	Compaction	No	Preserve state, inject summary context

EXECUTION ORDER

• UserPromptSubmit: keywordDetector → claudeCodeHooks → autoSlashCommand → startWork
• PreToolUse: subagentQuestionBlocker → questionLabelTruncator → claudeCodeHooks → nonInteractiveEnv → commentChecker → directoryAgentsInjector → directoryReadmeInjector → rulesInjector → prometheusMdOnly → sisyphusJuniorNotepad → writeExistingFileGuard → atlasHook
• PostToolUse: claudeCodeHooks → toolOutputTruncator → contextWindowMonitor → commentChecker → directoryAgentsInjector → directoryReadmeInjector → rulesInjector → emptyTaskResponseDetector → agentUsageReminder → interactiveBashSession → editErrorRecovery → delegateTaskRetry → atlasHook → taskResumeInfo → taskReminder

HOW TO ADD

1. Create src/hooks/name/ with index.ts exporting createMyHook(ctx)
2. Add hook name to HookNameSchema in src/config/schema.ts
3. Register in src/index.ts and add to relevant lifecycle methods

HOOK PATTERNS

Simple Single-Event:

export function createToolOutputTruncatorHook(ctx) {
  return { "tool.execute.after": async (input, output) => { ... } }
}

Multi-Event with State:

export function createThinkModeHook() {
  const state = new Map<string, ThinkModeState>()
  return {
    "chat.params": async (output, sessionID) => { ... },
    "event": async ({ event }) => { /* cleanup */ }
  }
}

ANTI-PATTERNS

• Blocking non-critical: Use PostToolUse warnings instead
• Heavy computation: Keep PreToolUse light to avoid latency
• Redundant injection: Track injected files to avoid context bloat
• Direct state mutation: Use output.output += instead of replacing