# User Feedback Log
## 2026-02-04: API Simplification Session
### Previous Session (summarized)
User requests for API cleanup:
1. "keep separate chroma tables and deringing methods. what did .tables() take? what is the need behind trellis and hybrid exposure?"
2. "tables, trellis, hybrid, expert - where do these overlap and not overlap? should progressive be an enum instead of a bool?"
3. "yes" (confirming .progressive(impl Into<ScanMode>) with From<bool>, removing trellis()/hybrid_config() direct methods)
4. "we have zero users, and apparently only one of our modes is a win over jpegli, yeah?"
5. "2. merge expertconfigs, make scanmode progressivescanmode"
### Current Session
1. User continued from context handoff - asked to continue API simplification work
2. "okay, encoder config full api" - requested full API listing
3. "you forgot all our api changes planned!" - reminder about planned API changes from previous session
4. "ugh fuck, did you at least track my previous messages in feedback.md" - no, I hadn't been logging feedback
### Planned Changes (from previous session)
- [x] Rename ScanMode to ProgressiveScanMode
- [x] Make HuffmanStrategy public with FixedAnnexK variant
- [x] Add From<bool> and From<HuffmanTableSet> for HuffmanStrategy
- [x] Add From<bool> for ProgressiveScanMode
- [x] Update .progressive() to accept impl Into<ProgressiveScanMode>
- [x] Add .huffman() method accepting impl Into<HuffmanStrategy>
- [x] Re-export HuffmanStrategy and ProgressiveScanMode in public API
- [x] Add .expert() method for ExpertConfig
- [x] Make .trellis() and .hybrid_config() #[doc(hidden)] (expert-only)
- [x] Simplify ExpertConfig to minimal overlay (tables + trellis + hybrid)
### Additional consolidation (this session)
- [x] Consolidate .scan_mode(), .scan_strategy(), .optimize_scans() under .progressive()
- [x] Consolidate .optimize_huffman(), .custom_huffman_tables() under .huffman()
- [x] Hide .effort constructors and .optimization() until design finalized
- [x] Benchmark: no performance regression with mozjpeg tables vs jpegli
### Final Public API
Constructors: ycbcr(), xyb(), grayscale()
Core: .quality(), .progressive(), .huffman(), .auto_optimize()
Knobs: .deringing(), .sharp_yuv(), .separate_chroma_tables(), .allow_16bit_quant_tables()
Expert: .expert(ExpertConfig) with .tables(), .trellis(), .hybrid()
Metadata: .icc_profile(), .exif(), .xmp()
## 2026-02-04: auto_optimize() Session
### User Request
1. "ok, our hybrid l14 mode is good or nah?" - Asked about HybMax-L14.5 performance
2. "okay, so let's use it in that range when people call .auto_optimize(true) on encoder config."
### Analysis
Reviewed R-D benchmark data from /mnt/v/output/zenjpeg/approach_rd_gb82.csv:
- HybMax-L14.5 vs JpegliProg: **10/10 wins** at matched BPP
- +0.4 to +1.8 SSIM2 improvement
- -0.03 to -0.13 Butteraugli improvement
- HybMax-L14.5 vs cjpegli-444: **9/10 wins**
- Only loss at very low quality (BPP <0.7)
### Implementation
Changed `.auto_optimize()` to `.auto_optimize(bool)`:
- When true: enables hybrid trellis with λ=14.5 + progressive
- Uses default jpegli quant tables (NOT CMA-ES scaling - they're incompatible)
- Quality threshold: q50+ (distance < 5.0)
### Test Results (flower_small.rgb.png, 510x532)
| 95 | 69428 | 89.4 | 68064 | 89.1 | -2.0% |
| 90 | 47704 | 86.9 | 46874 | 86.9 | -1.7% |
| 85 | 38116 | 84.5 | 37414 | 84.0 | -1.8% |
| 80 | 33238 | 82.2 | 32648 | 82.3 | -1.8% |
Consistent ~1.5-2% compression improvement with equal quality.