oh-my-opencode-slim/src/hooks/phase-reminder/codemap.md

src/hooks/phase-reminder/

Responsibility

Orchestrates phase reminder injection into user messages for the orchestrator agent, ensuring workflow guidance is appended without mutating the original message content or affecting UI display.

Design

Core Abstraction

• Hook Factory: createPhaseReminderHook() returns an OpenCode experimental chat message transformer hook
• Non-Mutating Strategy: Appends phase reminder as a separate message part rather than modifying user-authored text
• Targeted Injection: Only processes messages from the orchestrator agent

Key Components

• PHASE_REMINDER constant (imported from ../../config/constants)
• SLIM_INTERNAL_INITIATOR_MARKER constant (imported from ../../utils)
• Message part type checking and injection logic

Design Patterns

• Observer Pattern: Intercepts and transforms messages before API transmission without altering source
• Guard Clauses: Multiple preconditions prevent unnecessary processing:
  • Empty message check
  • User message existence check
  • Orchestrator agent check
  • Duplicate injection prevention
  • Internal initiator marker check

Flow

1. Hook Invocation: OpenCode calls the experimental.chat.messages.transform hook before sending messages to API
2. Message Analysis: Iterates backward through messages to find the last user message
3. Agent Validation: Confirms the message is from the orchestrator agent
4. Text Part Detection: Locates the text part in the message
5. Duplicate Prevention: Checks for existing phase reminder injection
6. Injection: Appends phase reminder as a new text message part
7. Transmission: Messages proceed to API with injected reminder (not visible in UI)

Integration

Dependencies

• Config: PHASE_REMINDER constant from ../../config/constants
• Utils: SLIM_INTERNAL_INITIATOR_MARKER from ../../utils
• Types: MessageWithParts type from ../types

Consumers

• OpenCode: Registers the hook via plugin initialization
• Orchestrator Agent: Receives phase reminders in messages
• API Layer: Receives messages with injected reminders (UI remains unaffected)

Context

• Execution Timing: Runs right before API transmission (post-UI rendering)
• Scope: Only affects orchestrator agent messages
• Persistence: Reminder is appended as a separate message part, preserving original content