---
phase: "02"
plan: "01"
subsystem: inf-parser
tags: [tdd, inf-parsing, encoding-detection, token-resolution, driver-management]
dependency_graph:
  requires: []
  provides: [inf-parser-service]
  affects: [02-02-upload-endpoint, 02-03-drivers-ui]
tech_stack:
  added: []
  patterns: [RawConfigParser-strict-false, BOM-sniffing, optionxform-str, set-dedup-sorted]
key_files:
  created:
    - imptune/services/__init__.py
    - imptune/services/inf_parser.py
    - tests/test_inf_parser.py
    - tests/fixtures/sample.inf
    - tests/fixtures/sample_utf16.inf
    - tests/fixtures/sample_multi_model.inf
  modified: []
decisions:
  - "optionxform=str on RawConfigParser to preserve DriverDesc key casing; strings dict still uses lowercased keys for case-insensitive %TOKEN% lookup"
  - "configparser.RawConfigParser(strict=False) avoids DuplicateOptionError on real INFs with repeated model entries"
  - "UTF-16 fixture written as binary via Python encode('utf-16') — not as a text file — to guarantee correct BOM bytes"
metrics:
  duration: "~2.5 min"
  completed: "2026-04-10"
  tasks: 1
  files: 6
requirements-completed: [DRV-02]
---

# Phase 02 Plan 01: INF Parser Service Summary

**One-liner:** stdlib configparser + BOM-sniffing INF parser with %TOKEN% resolution, multi-model deduplication, architecture detection, and unused-file flagging.

## What Was Built

`imptune/services/inf_parser.py` — a pure-function INF parser with:

- `ParsedInf` dataclass exposing `driver_names`, `inf_filename`, `architecture`, `has_cat_file`, `unused_files`
- `_detect_encoding(raw: bytes) -> str` — BOM-sniffing: `\xff\xfe`/`\xfe\xff` -> `utf-16`, `\xef\xbb\xbf` -> `utf-8-sig`, else `cp1252`
- `_resolve_tokens(value, strings)` — regex `%([^%]+)%` expansion
- `parse_inf(inf_text, inf_filename, zip_names) -> ParsedInf` — `RawConfigParser(strict=False, delimiters=('=',))` with `optionxform=str`; [Manufacturer] -> Models section discovery; NTamd64/NTarm64/NTx86/undecorated detection; set-based dedup; sorted output

Three fixture files support the test suite: `sample.inf` (ANSI with %TOKEN%), `sample_utf16.inf` (UTF-16 LE BOM binary), `sample_multi_model.inf` (NTamd64 + undecorated sections).

## Tasks

| # | Task | Status | Commit |
|---|------|--------|--------|
| 1 | INF parser with TDD (RED then GREEN) | Complete | 290106d (RED), 5056922 (GREEN) |

## Test Results

- 16 tests in `tests/test_inf_parser.py` — all pass
- Full suite: 40 tests pass, 0 failures, 0 regressions

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] configparser key lowercasing mangled DriverDesc literal names**
- **Found during:** Task 1, GREEN phase (first test run)
- **Issue:** configparser defaults `optionxform = str.lower`, so the literal key `Acme SuperPrint 9000` was returned as `acme superprint 9000`. The test `assert "Acme SuperPrint 9000" in result.driver_names` failed.
- **Fix:** Set `parser.optionxform = str` to preserve original casing of option keys. The [Strings] dict still explicitly lowercases keys (`strings[key.lower()]`) for case-insensitive token resolution.
- **Files modified:** `imptune/services/inf_parser.py`
- **Commit:** 5056922

**Note:** The plan specified `strict=False` and `RawConfigParser` correctly but did not mention `optionxform=str`. This is a real-INF edge case documented in the pitfalls section of 02-RESEARCH.md (implicitly — the note says "Strings dict keys must be lowercased" without clarifying that DriverDesc keys also get lowercased by default).

### Test Count Deviation

The plan specified 11 test functions; 16 were written. The extra 5 cover:
- `test_detect_encoding_utf16be` (UTF-16 BE BOM variant)
- `test_architecture_detection_amd64` (split from the combined architecture test)
- `test_architecture_detection_arm64`
- `test_architecture_detection_undecorated`
- `test_architecture_detection_mixed`

This provides more granular failure diagnosis and meets the `min_lines: 80` artifact requirement.

## Self-Check

- [x] `imptune/services/inf_parser.py` exists
- [x] `imptune/services/__init__.py` exists
- [x] `tests/test_inf_parser.py` exists (>80 lines)
- [x] `tests/fixtures/sample.inf` exists
- [x] `tests/fixtures/sample_utf16.inf` exists (UTF-16 LE BOM binary)
- [x] `tests/fixtures/sample_multi_model.inf` exists
- [x] RED commit: 290106d
- [x] GREEN commit: 5056922

## Self-Check: PASSED
