---
phase: 02-gemini-integration-asset-pipeline
plan: 04
subsystem: companion
tags: [gemini, ai-text, fallback, companion, german]

# Dependency graph
requires:
  - phase: 02-01
    provides: "generateText, checkRateLimit, incrementApiCall, loadConfig"
  - phase: 02-02
    provides: "fallback greetings, letter intros, forest comments"
provides:
  - "getGreeting: AI or fallback greeting with time-of-day context"
  - "getLetterIntro: AI or fallback letter introduction with finger description"
  - "getForestComment: AI or fallback forest element comment"
affects: [03-exercise-flow, 04-forest-rendering]

# Tech tracking
tech-stack:
  added: []
  patterns: [api-first-fallback, rate-limit-guard, companion-prompt-templates]

key-files:
  created: [src/companion/companion.ts, src/companion/companion.test.ts]
  modified: []

key-decisions:
  - "Prompt templates use ue/oe/ae transliteration consistent with codebase convention"
  - "Each function independently checks config and rate limits (no shared wrapper) for clarity"

patterns-established:
  - "API-first fallback: loadConfig -> checkRateLimit -> generateText -> fallback on any null"
  - "System prompts enforce max 25 words, simple German, no performance praise per COMP-04"

requirements-completed: [COMP-01, COMP-02, COMP-03, COMP-04]

# Metrics
duration: 1min
completed: 2026-03-29
---

# Phase 02 Plan 04: Companion Text Module Summary

**Companion text module with 3 exported functions (getGreeting, getLetterIntro, getForestComment) using Gemini API-first strategy with curated German fallbacks**

## Performance

- **Duration:** 1 min
- **Started:** 2026-03-29T10:04:46Z
- **Completed:** 2026-03-29T10:06:01Z
- **Tasks:** 1 (TDD: RED + GREEN)
- **Files modified:** 2

## Accomplishments
- Companion text module with API-first fallback strategy for all 3 dialogue types
- System prompts enforce max 25 words, simple German, no performance praise
- 13 tests covering API success, API failure, no config, and rate-limited paths

## Task Commits

Each task was committed atomically:

1. **Task 1 (RED): Companion test suite** - `6fba02c` (test)
2. **Task 1 (GREEN): Companion text module implementation** - `4b4aa8e` (feat)

_TDD task: test file committed first (RED), then implementation (GREEN)._

## Files Created/Modified
- `src/companion/companion.ts` - Companion text module with getGreeting, getLetterIntro, getForestComment
- `src/companion/companion.test.ts` - 13 tests covering all fallback paths and API integration

## Decisions Made
- Prompt templates use ue/oe/ae transliteration consistent with existing codebase convention
- Each function independently checks config and rate limits rather than using a shared wrapper, keeping the code straightforward and readable

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
None

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- Companion text module ready for integration into exercise flow
- All 3 functions exported and tested, ready for import by UI screens
- Depends on config.json with valid Gemini API key for AI-generated text; works without it via fallbacks

---
*Phase: 02-gemini-integration-asset-pipeline*
*Completed: 2026-03-29*
