refactor: rename initModularizedControllers to initMessengerClients and update result properties

[cryptodev-2s]

Description

Rename initModularizedControllers to initMessengerClients, drop existingControllersByName, rename controllerInitFunctions to initFunctions, and update return type to messengerClientsByName. Update all consumers in Engine.ts, utils.test.ts, and test utility functions.

80 files changed. PR 3 of 4 — depends on PR 2 (#28641).

• PR 1: Core type renames (Controller → MessengerClient, etc.) (refactor: rename Controller types to MessengerClient types #28610)
• PR 2: CONTROLLER_MESSENGERS → MESSENGER_FACTORIES (refactor: rename CONTROLLER_MESSENGERS to MESSENGER_FACTORIES #28641)
• PR 3 (this): initModularizedControllers → initMessengerClients + utils/Engine.ts renames
• PR 4: Property renames (controller → messengerClient, getController → getMessengerClient) in all init files + tests

Relates to WPC-916.

Changelog

CHANGELOG entry: null

Related issues

Fixes: https://consensyssoftware.atlassian.net/browse/WPC-916

Manual testing steps

Feature: Messenger client init system

  Scenario: App builds and runs normally
    Given the app is built from this branch

    When user opens the app
    Then the app behaves identically to main (no runtime behavior change)

Screenshots/Recordings

N/A — no UI changes.

Before

N/A

After

N/A

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• I've completed the PR template to the best of my ability
• I've included tests if applicable
• I've documented my code using JSDoc format if applicable
• I've applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

---

Note

Medium Risk
Refactors the Engine’s initialization wiring for all controller/messenger clients, so mistakes could break startup order or dependency resolution despite being a rename-focused change.

Overview
Renames and reshapes the Engine init helper by replacing initModularizedControllers with initMessengerClients, renaming controllerInitFunctions to initFunctions, and returning messengerClientsByName.

Simplifies initialization state by dropping support for existingControllersByName and updating the dependency lookup helper/error messaging to getMessengerClientOrThrow.

Updates Engine.ts wiring and a large set of controller init tests to use the new request mock helper (buildMessengerClientInitRequestMock) and the new result property names.

^{Reviewed by Cursor Bugbot for commit 80bf6e1. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.17%. Comparing base (9f195d0) to head (8522bad).
⚠️ Report is 32 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #28645      +/-   ##
==========================================
+ Coverage   82.14%   82.17%   +0.02%     
==========================================
  Files        4949     4967      +18     
  Lines      130070   130768     +698     
  Branches    29004    29168     +164     
==========================================
+ Hits       106851   107462     +611     
- Misses      15923    15977      +54     
- Partials     7296     7329      +33     

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[github-actions]

🔍 Smart E2E Test Selection

• Selected E2E tags: SmokeAccounts, SmokeConfirmations, SmokeNetworkAbstractions, SmokeNetworkExpansion, SmokeTrade, SmokeWalletPlatform, SmokeIdentity, SmokeRamps, SmokeMultiChainAPI, SmokePredictions, SmokePerps, SmokeSeedlessOnboarding, FlaskBuildTests
• Selected Performance tags: None (no tests recommended)
• Risk Level: medium
• AI Confidence: 82%

click to see 🤖 AI reasoning details

E2E Test Selection:
This PR is a pure refactoring/renaming of the Engine's controller initialization infrastructure:

1. Scope: 82 files changed, all within app/core/Engine/ - the core Engine initialization system
2. Nature: Terminology rename from "controller" to "messenger client" throughout:
   • initModularizedControllers → initMessengerClients
   • controllersByName → messengerClientsByName
   • controllerInitFunctions → initFunctions
   • buildControllerInitRequestMock → buildMessengerClientInitRequestMock
   • getControllerOrThrow → getMessengerClientOrThrow
3. Behavioral change: Removed existingControllersByName parameter from InitMessengerClientsFunctionRequest interface; the function now manages its own internal partialMessengerClientsByName state instead of accepting pre-existing controllers externally
4. Impact: Engine.ts is the central initialization point for ALL controllers (AccountsController, TransactionController, NetworkController, SignatureController, PerpsController, PredictController, SeedlessOnboardingController, etc.) - every feature in the app depends on these being initialized correctly

Why broad coverage: Although this is a rename/refactor, the Engine initialization is the foundation of the entire app. Any subtle bug introduced during this refactoring (e.g., the removal of existingControllersByName changing initialization order or dependency resolution) could break any feature. The conservative approach is to run all smoke test suites to verify the app still functions correctly end-to-end.

Why not high risk: The changes are purely cosmetic renames with no algorithmic changes to the initialization logic itself. The unit tests have been updated to match. The removal of existingControlgersByName is reflected in the updated test that removed the 'not throws when existing controller is found' test case.

Performance Test Selection:
This PR is a pure refactoring/renaming of internal Engine initialization code. No UI components, rendering logic, data loading patterns, or performance-sensitive code paths were changed. The rename from 'controller' to 'messenger client' terminology does not affect runtime performance characteristics. No performance tests are warranted.

View GitHub Actions results

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

✅ E2E Fixture Validation — Schema is up to date
11 value mismatches detected (expected — fixture represents an existing user).
View details