cmd: add API partial deposit flow

[KaloyanTanev]

1. charon deposit sign: sign partial deposit -> publish to the api
2. charon deposit fetch: fetch deposits from the api -> aggregate signatures -> save full deposit locally

category: feature
ticket: #3992

[codecov]

Codecov Report

❌ Patch coverage is 65.76923% with 89 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.93%. Comparing base (7e84819) to head (6a73eb1).

Files with missing lines	Patch %	Lines
cmd/depositsign.go	64.35%	19 Missing and 17 partials ⚠️
app/obolapi/deposit.go	61.17%	18 Missing and 15 partials ⚠️
cmd/depositfetch.go	74.50%	6 Missing and 7 partials ⚠️
cmd/cmd.go	0.00%	4 Missing ⚠️
app/obolapi/api.go	0.00%	2 Missing ⚠️
cmd/exit_delete.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4032      +/-   ##
==========================================
+ Coverage   54.81%   54.93%   +0.11%     
==========================================
  Files         242      246       +4     
  Lines       31040    31295     +255     
==========================================
+ Hits        17014    17191     +177     
- Misses      11785    11827      +42     
- Partials     2241     2277      +36     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[pinebit]

LGTM for the first pass.

[sonarqubecloud]

Quality Gate failed

Failed conditions
15.2% Duplication on New Code (required ≤ 15%)

See analysis details on SonarQube Cloud

[DiogoSantoss]

Can we do make([]eth2p0.DepositData,dr.Amounts)? and then later fullDeposits[i]=... ?

[KaloyanTanev]

What do we gain from filling the slice with empty objects which we later overwrite over creating an empty one to which we later on amend new objects?

I personally never liked empty objects in slices as it's really error prone and useful only in specific cases.

[DiogoSantoss]

make([]eth2p0.BLSPubKey,config.ValidatorPublicKeys) and then pubkeys[i]=blsPK

[Copilot]

Pull Request Overview

This pull request introduces deposit signing and fetching functionality for distributed validators, enabling operators to sign and fetch deposit messages through the Obol API. The key purpose is to allow modification of withdrawal addresses after creation but before validator activation.

Key changes:

• Added new CLI commands for deposit signing (deposit sign) and fetching (deposit fetch)
• Created deposit handling API endpoints and mock server implementation
• Refactored common code by extracting shared utilities from exit.go to obolapi.go
• Renamed ErrNoExit to ErrNoValue to make it reusable for both exits and deposits

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
testutil/obolapimock/obolapi.go	New file containing extracted common mock server utilities (testServer, auth middleware, helper functions)
testutil/obolapimock/exit.go	Removed duplicated code that was moved to obolapi.go, kept exit-specific logic
testutil/obolapimock/deposit.go	New file implementing mock deposit API handlers (submit partial, fetch full)
cmd/deposit.go	New file defining shared deposit command configuration and flags
cmd/depositsign.go	New file implementing deposit signing command logic
cmd/depositfetch.go	New file implementing deposit fetching command logic
cmd/depositsign_internal_test.go	New test file for deposit signing functionality
cmd/depositfetch_internal_test.go	New test file for deposit fetching functionality
cmd/cmd.go	Added deposit commands to the root command
app/obolapi/deposit.go	New file implementing client-side deposit API calls
app/obolapi/deposit_model.go	New file defining deposit API request/response models
app/obolapi/deposit_test.go	New test file for deposit API integration
app/obolapi/exit.go	Renamed ErrNoExit to ErrNoValue
app/obolapi/exit_test.go	Renamed test functions to be more specific (TestAPIExit, TestAPIExitMissingSig)
app/obolapi/api.go	Updated to use renamed ErrNoValue
cmd/exit_fetch.go	Updated to use renamed ErrNoValue
cmd/exit_delete.go	Updated to use renamed ErrNoValue
cmd/exit_broadcast.go	Updated to use renamed ErrNoValue

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.