---
phase: 02-exness-daily-tick-cache-seeder-service-with-registry-integration
plan: 02
subsystem: scripts
tags: [exness, forex, parquet, seeder, polars, requests]

# Dependency graph
requires:
  - phase: 02-01
    provides: "ExnessSeederConfig and 10 Exness symbols in symbols.toml"
provides:
  - "Exness forex tick cache seeder script (scripts/exness_tick_cache_seeder.py)"
  - "8 unit tests covering download, parse, write, idempotency, state file, registry"
affects: [02-03-systemd-monit-deployment]

# Tech tracking
tech-stack:
  added: []
  patterns: ["Exness ZIP download + Polars CSV parse + atomic Parquet write"]

key-files:
  created:
    - scripts/exness_tick_cache_seeder.py
    - tests/test_exness_seeder.py
    - python/opendeviationbar/config/exness_seeder.py
  modified: []

key-decisions:
  - "Pure Python HTTP download via requests (not Rust ExnessFetcher via PyO3) -- matches Binance seeder pattern"
  - "Bypass write_ticks(), use _atomic_write_parquet() directly -- Exness has no agg_trade_id for dedup"
  - "ExnessSeederConfig created as Rule 3 deviation since Plan 01 runs in parallel"

patterns-established:
  - "Exness cache key prefix: EXNESS_RAW_SPREAD_{SYMBOL}"
  - "3-column Parquet schema for forex quotes: timestamp (ms), bid (f64), ask (f64)"
  - "Strip Z suffix from Exness ISO 8601 timestamps before Polars parsing"

requirements-completed: [EXNS-DL, EXNS-PARSE, EXNS-WRITE, EXNS-IDEM, EXNS-TEL]

# Metrics
duration: 7min
completed: 2026-03-23
---

# Phase 02 Plan 02: Exness Seeder Script Summary

**Exness forex tick cache seeder downloading daily ZIPs from ticks.ex2archive.com with 3-column Parquet output, idempotent operation, and Telegram reporting**

## Performance

- **Duration:** 7 min
- **Started:** 2026-03-23T19:37:50Z
- **Completed:** 2026-03-23T19:44:30Z
- **Tasks:** 2
- **Files created:** 3

## Accomplishments

- Complete Exness seeder script (442 lines) mirroring Binance seeder architecture
- 8 unit tests covering EXNS-01 through EXNS-07 from research test map
- Weekend 404s silently skipped at DEBUG level (forex markets closed Sat/Sun)
- Idempotent operation: existing Parquet files not re-downloaded
- Telegram reporting: ephemeral on success (disable_notification=True), persistent on failure

## Task Commits

Each task was committed atomically:

1. **Task 1: Create Exness seeder script** - `1f4df03` (feat)
2. **Task 2: Add unit tests** - `0d23478` (test)

## Files Created/Modified

- `scripts/exness_tick_cache_seeder.py` - Main seeder script: download, parse, write pipeline
- `tests/test_exness_seeder.py` - 8 unit tests covering EXNS-01 through EXNS-07
- `python/opendeviationbar/config/exness_seeder.py` - ExnessSeederConfig (pydantic-settings)

## Decisions Made

- Used pure Python HTTP download via `requests` instead of Rust ExnessFetcher -- matches Binance seeder pattern exactly, avoids PyO3 conversion overhead
- Bypassed `write_ticks()` and used `_atomic_write_parquet()` directly -- Exness quote data has no `agg_trade_id` column, so trade-ID dedup validation is irrelevant
- Created ExnessSeederConfig as Rule 3 deviation since Plan 01 (which normally creates it) runs in parallel

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 3 - Blocking] Created ExnessSeederConfig (Plan 01 dependency)**

- **Found during:** Task 1 (seeder script creation)
- **Issue:** Plan 02 depends on `python/opendeviationbar/config/exness_seeder.py` created by Plan 01, but Plan 01 runs in parallel and hasn't completed yet
- **Fix:** Created minimal ExnessSeederConfig with correct fields (historical_start, max_concurrent_downloads, download_timeout_s, state_file) matching the interface specification
- **Files modified:** `python/opendeviationbar/config/exness_seeder.py`
- **Verification:** Seeder script imports and uses the config correctly
- **Committed in:** `1f4df03` (Task 1 commit)

---

**Total deviations:** 1 auto-fixed (1 blocking)
**Impact on plan:** Necessary for parallel execution. Plan 01 may create a more complete version; this is the minimal interface needed.

## Issues Encountered

- pytest-timeout plugin not available in this worktree -- ran tests without --timeout flag
- Test EXNS-07 (registry entries count) skipped because Exness symbols not yet in symbols.toml (Plan 01 parallel dependency)

## Known Stubs

None -- all functions are fully implemented with real logic, no placeholder data.

## User Setup Required

None - no external service configuration required.

## Next Phase Readiness

- Seeder script ready for systemd service deployment (Plan 03)
- Requires Plan 01 completion to add Exness symbols to symbols.toml before production use
- Tests designed to pass both with and without Plan 01 completion (graceful skips)

## Self-Check: PASSED

- scripts/exness_tick_cache_seeder.py: FOUND
- tests/test_exness_seeder.py: FOUND
- python/opendeviationbar/config/exness_seeder.py: FOUND
- Commit 1f4df03: FOUND
- Commit 0d23478: FOUND

---

_Phase: 02-exness-daily-tick-cache-seeder-service-with-registry-integration_
_Completed: 2026-03-23_
