refactor: remove obsolete database migration controller

[BrandonStalnaker]

Background

• The persistence migration now uses the Swift implementation, leaving MPDatabaseMigrationController unused with no remaining callers.

What Has Changed

• Removed the obsolete Objective-C MPDatabaseMigrationController header and implementation.
• Removed its references from the Xcode project.

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Reference Issue (For employees only. Ignore if you are an outside contributor)

• Closes https://go/j/[ticket-number]

Summary by CodeRabbit

• Refactor

  • Removed legacy database migration handling from the SDK.
  • Related migration APIs and processing are no longer included.

• User Impact

  • Standard integrations should not experience changes to user-facing SDK functionality.
  • Existing applications relying on the removed database migration behavior may require updates to maintain compatibility.

[cursor]

PR Summary

Medium Risk
Touches on-device persistence migration code paths; risk is low if Swift migration is the only active path, but regressions would affect upgrades from older DB versions.

Overview
Removes the unused Objective-C MPDatabaseMigrationController (.h/.m) and drops it from the Xcode target’s headers, sources, and Persistence group.

Local SQLite upgrade paths that this class implemented (sessions, messages, uploads, forwarding records, consumer info/cookies, integration attributes, old-record pruning) are already covered by the Swift persistence stack (MPDatabaseMigrator / MPDatabaseMigrationLogicPRIVATE); this change is dead-code cleanup with no intended public API change.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: QUIET

Plan: Advanced

Run ID: 2b52cda6-ac90-4441-a42b-17b51a12ac07

📥 Commits

Reviewing files that changed from the base of the PR and between 130e2d0 and 676303b.

📒 Files selected for processing (1)

• mParticle-Apple-SDK.xcodeproj/project.pbxproj

💤 Files with no reviewable changes (1)

• mParticle-Apple-SDK.xcodeproj/project.pbxproj

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📝 Walkthrough

Walkthrough

The pull request removes MPDatabaseMigrationController, including its Objective-C interface and database migration implementation. It also removes all related file references and build-phase entries from the Xcode project.

Changes

Database migration controller removal

Layer / File(s)	Summary
Remove migration controller implementation mParticle-Apple-SDK/Persistence/MPDatabaseMigrationController.h, mParticle-Apple-SDK/Persistence/MPDatabaseMigrationController.m	Deletes the controller interface and its database migration, cleanup, transfer, and database-file handling methods.
Remove Xcode target integration mParticle-Apple-SDK.xcodeproj/project.pbxproj	Removes the controller from project file references, the Persistence group, header build files, source build files, and target build phases.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 67630

The obsolete Objective-C migration controller and project references are removed in favor of the Swift implementation, with no identified merge-blocking risk.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: removal of the obsolete MPDatabaseMigrationController and its project references.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor/Remove-DB-Migration-Controller

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[github-actions]

🐦 Swift Migration Progress

Production implementation code at 676303bad475 compared with abbf3bfe0a1d.

Area	Goal	Progress	Base	This PR	Swift SLOC	Objective-C remaining	Change
Core SDK	Short term — in scope	███████▏░░	70.38%	71.51%	11,476	4,571	🚀 +1.13 pp
Core SDK	Long term — all Objective-C	█████▏░░░░	50.99%	51.58%	11,476	10,771	🚀 +0.59 pp
SDK kit infrastructure	Short term — in scope	███████▍░░	73.45%	73.45%	2,031	734	➖ 0.00 pp
SDK kit infrastructure	Long term — all Objective-C	████░░░░░░	39.81%	39.81%	2,031	3,071	➖ 0.00 pp
Standalone kits	Short term — in scope	▋░░░░░░░░░	5.84%	5.84%	864	13,921	➖ 0.00 pp
Standalone kits	Long term — all Objective-C	▋░░░░░░░░░	5.84%	5.84%	864	13,921	➖ 0.00 pp

Objective-C retained by design: Core SDK 6,200 · SDK kit infrastructure 2,337 · Standalone kits 0.

This PR's code movement

Area	Swift lines added	Objective-C lines removed
Core SDK	0	340
SDK kit infrastructure	0	0
Standalone kits	0	0

How this is measured

• Current composition uses production source lines of code (SLOC) from cloc; comments and blank lines are excluded.
• Short term — in scope excludes the Objective-C the migration will not delete, so 100% is the end of this project: every in-scope implementation gone.
• Long term — all Objective-C keeps the full denominator. Reaching 100% there means the public API itself becomes Swift, which is a breaking change reserved for a future major release.
• The gap between the two rows is the retained public/kit contract, runtime-identity, and boundary-glue surface listed in Tools/swift-migration-retained-objc.txt.
• Retained wrappers keep their Objective-C interface but still shed logic to Swift. That thinning moves the long-term row and the retained figure, not the short-term row.
• Both revisions are measured with the manifest from the head revision, so a manifest edit does not by itself move the reported change. A retained file this pull request renamed or deleted still counts as retained at the base.
• Pull request movement uses physical additions/deletions from git diff base...head --numstat; it counts retained files too and is intentionally separate from SLOC totals.
• Core excludes SDK kit infrastructure and vendored libraries. Standalone kits include only files below Kits/**/Sources.
• Tests, examples, headers, build outputs, vendored libraries, and the MParticle/Sources Swift overlay are excluded.
• Objective-C++ (.mm) is included in the Objective-C figures and removed counts.

Generated with cloc 2.10. This report is informational and does not gate migration direction.

[github-actions]

📦 SDK Size Impact Report

Measures how much the SDK adds to an app's size (with-SDK minus without-SDK).

Metric	Target Branch	This PR	Change
App Bundle Impact	2.68 MB	2.66 MB	-20 KB
Executable Impact	848 bytes	848 bytes	+N/A
XCFramework Size	6.84 MB	6.77 MB	-72 KB

➡️ SDK size impact change is minimal.

Raw measurements

Target branch (workstation/swift-migration):

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":2824,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":2740,"sdk_executable_impact_bytes":848,"xcframework_size_kb":7000}

This PR:

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":2804,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":2720,"sdk_executable_impact_bytes":848,"xcframework_size_kb":6928}