Backend layer domain should not use other layers

[oliver3]

Move non-domain usages out of domain::committee_session_status and domain::file, in separate commits:

• Separate change_committee_session_status() into new layer service because it is more orchestration than domain logic, including audit logging.
• Move file::create_file() to its only usage, and inline file::delete_file() into delete_committee_session_files()
• Move CommitteeSessionError out of api into domain, so that it can be used there and add a ProviderError variant

Questions:

• Are services a new layer or should it somehow live under the api layer?

[github-actions]

Sigrid maintainability feedback

↗️ You improved your code towards your objective of 3.5 stars.

Show details

Sigrid compared your code against the baseline of 2026-02-05.

👍 What went well?

You fixed or improved 41 refactoring candidates.

Risk	System property	Location
🔴	Duplication (Fixed)	backend/src/api/report.rs line 543-559 backend/src/api/document.rs line 198-214
🔴	Duplication (Fixed)	backend/src/api/committee_session.rs line 178-189 backend/src/api/election.rs line 185-196
🔴	Duplication (Fixed)	backend/src/api/data_entry.rs line 426-432 backend/src/api/data_entry.rs line 577-583 backend/src/api/data_entry.rs line 549-555 + 1 occurrences
🔴	Duplication (Fixed)	backend/src/api/polling_station.rs line 338-346 backend/src/api/polling_station.rs line 417-425
🔴	Duplication (Fixed)	backend/src/api/investigation.rs line 115-121 backend/src/api/polling_station.rs line 262-268
🔴	Duplication (Fixed)	backend/src/api/investigation.rs line 396-402 backend/src/api/polling_station.rs line 290-296 backend/src/api/investigation.rs line 328-334
🔴	Duplication (Fixed)	backend/src/domain/committee_session_status.rs line 163-170 backend/src/domain/committee_session_status.rs line 188-195
🔴	Duplication (Fixed)	backend/src/api/election.rs line 102-109 backend/src/api/data_entry.rs line 1007-1014
⚫️		+ 33 more

👎 What could be better?

Unfortunately, 43 refactoring candidates were introduced or got worse.

Risk	System property	Location
🔴	Duplication (Introduced)	backend/src/api/polling_station.rs line 143-160 backend/src/api/investigation.rs line 153-170
🔴	Duplication (Introduced)	backend/src/api/report.rs line 489-505 backend/src/api/document.rs line 39-55 backend/src/api/document.rs line 118-134
🔴	Duplication (Introduced)	backend/src/api/report.rs line 560-576 backend/src/api/document.rs line 198-214
🔴	Duplication (Introduced)	backend/src/api/investigation.rs line 427-442 backend/src/api/report.rs line 560-575 backend/src/api/document.rs line 198-213
🔴	Duplication (Introduced)	backend/src/api/data_entry.rs line 817-831 backend/src/api/data_entry.rs line 941-955
🔴	Duplication (Introduced)	backend/src/api/data_entry.rs line 382-393 backend/src/api/data_entry.rs line 519-530
🔴	Duplication (Introduced)	backend/src/api/data_entry.rs line 424-436 backend/src/api/data_entry.rs line 575-591
🔴	Duplication (Introduced)	backend/src/api/polling_station.rs line 318-333 backend/src/api/investigation.rs line 409-424
⚫️		+ 35 more

📚 Remaining technical debt

83 refactoring candidates didn't get better or worse, but are still present in the code you touched.

View this system in Sigrid to explore your technical debt

⭐️ Sigrid ratings

System property	System on 2026-02-05	Before changes	New/changed code
Volume	3.4	N/A	N/A
Duplication	3.7	3.1	3.1
Unit Size	2.2	1.7	1.7
Unit Complexity	3.2	4.2	4.2
Unit Interfacing	3.0	0.6	0.7
Module Coupling	3.4	3.9	4.6
Component Independence	2.0	N/A	N/A
Component Entanglement	2.4	N/A	N/A
Maintainability	2.9	3.1	3.3

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[codecov]

Codecov Report

❌ Patch coverage is 93.80531% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.37%. Comparing base (ee1c92c) to head (9a32251).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
backend/src/error.rs	42.85%	4 Missing ⚠️
...end/src/service/change_committee_session_status.rs	96.38%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2864   +/-   ##
=======================================
  Coverage   91.37%   91.37%           
=======================================
  Files         379      380    +1     
  Lines       17639    17654   +15     
  Branches     1987     1987           
=======================================
+ Hits        16117    16131   +14     
- Misses       1424     1425    +1     
  Partials       98       98           

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[github-actions]

PDF Diff Summary

Comparing against base branch: main

File	Status
model-n-10-2.pdf	✅ No changes
model-na-14-2-bijlage1.pdf	✅ No changes
model-na-14-2.pdf	✅ No changes
model-na-31-2-bijlage1.pdf	✅ No changes
model-na-31-2-inlegvel.pdf	✅ No changes
model-na-31-2.pdf	✅ No changes
model-p-2a.pdf	✅ No changes