fix: Items propagation in MapInternal + null dict→empty + benchmark cleanup

[cloud-hai-vo]

Closes #75

Summary

Fixes found by 3-agent code review of PR #73:

• Items propagation (HIGH): GetContext(items) now used in MapInternal's base-type walk, interface walk, and collection auto-mapping paths. Previously Items were silently dropped for EF Core proxy types.
• Null dictionaries → empty: Dictionary<K,V> properties now produce empty dict when source is null, matching collection behavior
• Benchmark workflow: Closes stale benchmark PRs before creating new one + enables gh pr merge --auto --squash

Test plan

• 333 unit tests pass on net8.0, net9.0, net10.0
• All analyzer/generator/class-mapper tests pass

🤖 Generated with Claude Code

[github-actions]

📊 Benchmark Results

Generated: 2026-03-25 06:59 UTC  ·  Download full artifacts

Column guide:
Mean = average execution time  ·  Error = half of 99.9 % confidence interval  ·  StdDev = standard deviation  ·  Min / Median / Max = statistical range  ·  Ratio = vs Manual baseline (lower = closer to hand-written speed)  ·  RatioSD = ratio std dev  ·  Rank = 1 is fastest  ·  Gen0/1/2 = GC collections per 1 000 ops  ·  Allocated = managed heap per operation  ·  Alloc Ratio = allocation ratio vs baseline

🔵 Flat Mapping — 10-property object

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Allocated	Alloc Ratio
Manual	15.52 ns	8.036 ns	0.440 ns	15.19 ns	15.35 ns	16.02 ns	1.00	0.03	1	0.0048	80 B	1.00
EggMapper	27.48 ns	6.228 ns	0.341 ns	27.15 ns	27.47 ns	27.83 ns	1.77	0.05	2	0.0048	80 B	1.00
AutoMapper	82.36 ns	12.758 ns	0.699 ns	81.91 ns	81.99 ns	83.16 ns	5.31	0.13	3	0.0048	80 B	1.00
Mapster	27.81 ns	9.164 ns	0.502 ns	27.31 ns	27.80 ns	28.32 ns	1.79	0.05	2	0.0048	80 B	1.00
MapperlyMap	15.36 ns	9.929 ns	0.544 ns	14.90 ns	15.22 ns	15.96 ns	0.99	0.04	1	0.0048	80 B	1.00
AgileMapper	508.64 ns	107.630 ns	5.900 ns	502.11 ns	510.25 ns	513.57 ns	32.78	0.86	4	0.0200	344 B	4.30
EggMapperGenerator	15.52 ns	1.860 ns	0.102 ns	15.45 ns	15.47 ns	15.64 ns	1.00	0.02	1	0.0048	80 B	1.00
EggMapperClassMapper	15.12 ns	8.444 ns	0.463 ns	14.67 ns	15.09 ns	15.59 ns	0.97	0.04	1	0.0048	80 B	1.00

🟡 Flattening — 2 nested objects → 8 flat properties

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Allocated	Alloc Ratio
Manual	19.24 ns	11.042 ns	0.605 ns	18.55 ns	19.47 ns	19.69 ns	1.00	0.04	1	0.0048	80 B	1.00
EggMap	29.38 ns	10.435 ns	0.572 ns	29.03 ns	29.06 ns	30.04 ns	1.53	0.05	3	0.0048	80 B	1.00
AutoMapper	94.33 ns	16.325 ns	0.895 ns	93.48 ns	94.26 ns	95.26 ns	4.91	0.14	5	0.0048	80 B	1.00
Mapster	36.27 ns	9.919 ns	0.544 ns	35.88 ns	36.05 ns	36.89 ns	1.89	0.06	4	0.0048	80 B	1.00
MapperlyMap	23.94 ns	7.365 ns	0.404 ns	23.51 ns	24.02 ns	24.30 ns	1.25	0.04	2	0.0062	104 B	1.30
AgileMapper	510.68 ns	112.871 ns	6.187 ns	506.62 ns	507.63 ns	517.80 ns	26.57	0.79	6	0.0200	344 B	4.30

🟣 Deep Mapping — 2 nested address objects

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Allocated	Alloc Ratio
Manual	55.79 ns	22.210 ns	1.217 ns	54.38 ns	56.41 ns	56.57 ns	1.00	0.03	1	0.0162	272 B	1.00
EggMapper	65.89 ns	41.507 ns	2.275 ns	63.70 ns	65.72 ns	68.24 ns	1.18	0.04	1	0.0162	272 B	1.00
AutoMapper	119.17 ns	8.505 ns	0.466 ns	118.66 ns	119.27 ns	119.58 ns	2.14	0.04	2	0.0162	272 B	1.00
Mapster	68.37 ns	5.167 ns	0.283 ns	68.06 ns	68.43 ns	68.61 ns	1.23	0.02	1	0.0162	272 B	1.00
MapperlyMap	50.00 ns	32.153 ns	1.762 ns	48.07 ns	50.41 ns	51.52 ns	0.90	0.03	1	0.0162	272 B	1.00
AgileMapper	517.03 ns	79.086 ns	4.335 ns	512.08 ns	518.81 ns	520.18 ns	9.27	0.19	3	0.0248	424 B	1.56

🟢 Complex Mapping — nested object + collection

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Allocated	Alloc Ratio
Manual	73.02 ns	61.18 ns	3.354 ns	70.82 ns	71.36 ns	76.88 ns	1.00	0.06	1	0.0191	320 B	1.00
EggMapper	95.53 ns	24.30 ns	1.332 ns	93.99 ns	96.22 ns	96.37 ns	1.31	0.05	2	0.0191	320 B	1.00
AutoMapper	161.95 ns	53.19 ns	2.915 ns	159.04 ns	161.95 ns	164.87 ns	2.22	0.09	3	0.0196	328 B	1.02
Mapster	92.53 ns	47.15 ns	2.584 ns	89.54 ns	94.00 ns	94.04 ns	1.27	0.06	2	0.0191	320 B	1.00
MapperlyMap	74.29 ns	26.77 ns	1.467 ns	72.96 ns	74.04 ns	75.86 ns	1.02	0.04	1	0.0191	320 B	1.00
AgileMapper	581.39 ns	38.83 ns	2.128 ns	579.13 ns	581.68 ns	583.36 ns	7.97	0.31	4	0.0315	528 B	1.65

🟠 Collection — 100-item List<T>

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Gen1	Allocated	Alloc Ratio
Manual	2.100 μs	0.8641 μs	0.0474 μs	2.046 μs	2.119 μs	2.135 μs	1.00	0.03	1	0.5264	0.0153	8.65 KB	1.00
EggMapper	1.854 μs	0.6459 μs	0.0354 μs	1.832 μs	1.836 μs	1.895 μs	0.88	0.02	1	0.5283	0.0172	8.65 KB	1.00
AutoMapper	2.535 μs	0.7886 μs	0.0432 μs	2.486 μs	2.550 μs	2.568 μs	1.21	0.03	2	0.6065	0.0191	9.95 KB	1.15
Mapster	1.910 μs	0.2434 μs	0.0133 μs	1.902 μs	1.903 μs	1.925 μs	0.91	0.02	1	0.5283	0.0172	8.65 KB	1.00
MapperlyMap	1.927 μs	0.7883 μs	0.0432 μs	1.894 μs	1.912 μs	1.976 μs	0.92	0.03	1	0.5283	0.0172	8.65 KB	1.00
AgileMapper	2.563 μs	0.8893 μs	0.0487 μs	2.518 μs	2.556 μs	2.615 μs	1.22	0.03	2	0.5417	0.0153	8.91 KB	1.03

🟠 Collection — 100-item List<T>

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Gen1	Allocated	Alloc Ratio
Manual	5.526 μs	3.7738 μs	0.2069 μs	5.398 μs	5.415 μs	5.764 μs	1.00	0.05	1	1.6708	0.0916	27.4 KB	1.00
EggMapper	6.187 μs	1.9524 μs	0.1070 μs	6.069 μs	6.214 μs	6.277 μs	1.12	0.04	1	1.6708	0.0916	27.4 KB	1.00
AutoMapper	7.232 μs	2.8246 μs	0.1548 μs	7.057 μs	7.288 μs	7.352 μs	1.31	0.05	1	1.7548	0.1068	28.7 KB	1.05
Mapster	6.321 μs	2.4116 μs	0.1322 μs	6.174 μs	6.358 μs	6.430 μs	1.14	0.04	1	1.6708	0.0916	27.4 KB	1.00
MapperlyMap	5.481 μs	2.3854 μs	0.1308 μs	5.374 μs	5.441 μs	5.627 μs	0.99	0.04	1	1.6785	0.0992	27.42 KB	1.00
AgileMapper	5.446 μs	0.3478 μs	0.0191 μs	5.425 μs	5.449 μs	5.462 μs	0.99	0.03	1	1.0223	0.0610	16.72 KB	0.61

🟠 Collection — 100-item List<T>

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Gen1	Allocated	Alloc Ratio
Manual	17.60 μs	6.639 μs	0.364 μs	17.19 μs	17.76 μs	17.87 μs	1.00	0.03	1	5.2490	1.3123	85.99 KB	1.00
EggMapper	16.67 μs	4.832 μs	0.265 μs	16.48 μs	16.55 μs	16.97 μs	0.95	0.02	1	5.2490	1.3123	85.99 KB	1.00
AutoMapper	21.96 μs	3.726 μs	0.204 μs	21.74 μs	21.99 μs	22.14 μs	1.25	0.02	1	5.7678	1.4343	94.34 KB	1.10
Mapster	17.44 μs	9.951 μs	0.545 μs	16.91 μs	17.41 μs	18.00 μs	0.99	0.03	1	5.2490	1.3123	85.99 KB	1.00
MapperlyMap	18.88 μs	5.307 μs	0.291 μs	18.56 μs	18.93 μs	19.14 μs	1.07	0.02	1	5.2490	1.2817	86.02 KB	1.00
AgileMapper	21.02 μs	6.506 μs	0.357 μs	20.64 μs	21.06 μs	21.35 μs	1.19	0.03	1	5.2795	1.3123	86.25 KB	1.00

⚪ Startup / Configuration time

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Gen1	Allocated	Alloc Ratio
EggMapperStartup	1,295.658 μs	1,468.1429 μs	80.4739 μs	1,242.255 μs	1,256.502 μs	1,388.216 μs	1.002	0.08	3	3.9063	1.9531	94.85 KB	1.00
AutoMapperStartup	423.861 μs	1,259.2774 μs	69.0252 μs	349.290 μs	436.777 μs	485.516 μs	0.328	0.05	2	5.8594	-	104.03 KB	1.10
MapsterStartup	2.560 μs	0.8103 μs	0.0444 μs	2.509 μs	2.584 μs	2.587 μs	0.002	0.00	1	0.7019	0.0267	11.51 KB	0.12

EggMapper.Benchmarks.ColdStartBenchmark-report-github

Method	Mean	Error	StdDev	Min	Median	Max	Ratio	RatioSD	Rank	Gen0	Gen1	Allocated	Alloc Ratio
EggMapper	1.283 ms	1.302 ms	0.0714 ms	1.240 ms	1.244 ms	1.365 ms	1.00	0.07	1	5.8594	-	95.47 KB	1.00
AutoMapper	4.052 ms	9.674 ms	0.5303 ms	3.554 ms	3.994 ms	4.609 ms	3.16	0.39	2	15.6250	7.8125	310.03 KB	3.25
Mapster	4.198 ms	11.940 ms	0.6545 ms	3.554 ms	4.176 ms	4.863 ms	3.28	0.47	2	39.0625	15.6250	754.87 KB	7.91

---

📝 Notes

• Each benchmark class is decorated with [MemoryDiagnoser] and [RankColumn].
• The global config (see src/EggMapper.Benchmarks/Program.cs) adds Min, Median, and Max columns.
• Manual is the hand-written baseline (ratio = 1.00). A ratio < 1 means faster than manual.
• Benchmarks run on GitHub-hosted runners — absolute times may vary between runs; focus on Ratio for comparisons.
• To reproduce locally:

  cd src/EggMapper.Benchmarks
  dotnet run --configuration Release -- --filter '*'