Fix RTR user agent after app restart

[wmathurin]

Summary

• Bind token refresh requests to the credential owner’s explicit per-user User-Agent instead of ambient current-user state.
• Add deterministic coverage for a different current user, explicit token-request header construction/fallback, and DPoP nonce-retry User-Agent preservation.
• Add an AuthFlowTester cold-restart regression that captures the actual /services/oauth2/token User-Agent and requires RT, A2, and OT.
• Document the first-post-restart refresh invariant.

Why no timestamp reconciliation

No persisted-state repair is needed. Warm refreshes later in the original process already carry RT, and the post-restart regression passes once refresh resolves the credential owner explicitly. The failing request also omitted other per-user markers, confirming request-context loss rather than RT persistence loss.

Validation

• Pre-fix focused regression failed as expected: the endpoint request had no explicit UA and omitted the owner’s RT/test markers.
• Focused SalesforceSDKCore tests: 10 passed, 0 failed, 0 skipped.
• DPoP nonce-retry User-Agent regression: 1 passed, 0 failed; full SFSDKOAuthTokenEndpointResponseTests: 5 passed, 0 failed, 0 skipped.
• AuthFlowTester build-for-testing passed.
• Focused live AuthFlowTester UI regression: 1 passed, 0 failed (103.817s).
• git diff --check passes.

Workspace spec

• https://git.soma.salesforce.com/SalesforceMobileSDK/SalesforceMobileSDK-Workspace/pull/99

Work item

• W-24141870

[github-actions]

	Tests	Passed ✅	Skipped	Failed
SalesforceSDKCore iOS ^18 Test Results	1039 ran	1039 ✅

Test	Result
No test annotations available

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.88%. Comparing base (48982e7) to head (d78f7bc).
⚠️ Report is 1 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #4171      +/-   ##
==========================================
+ Coverage   67.28%   70.88%   +3.60%     
==========================================
  Files         254      254              
  Lines       22993    22998       +5     
==========================================
+ Hits        15470    16303     +833     
+ Misses       7523     6695     -828     

Components	Coverage Δ
Analytics	70.78% <ø> (ø)
Common	70.88% <ø> (ø)
Core	66.27% <100.00%> (+5.40%)	⬆️
SmartStore	73.45% <ø> (ø)
MobileSync	88.99% <ø> (ø)

Files with missing lines	Coverage Δ
...rceSDKCore/Classes/OAuth/SFOAuthSessionRefresher.m	93.47% <100.00%> (+0.21%)	⬆️
...KCore/SalesforceSDKCore/Classes/Util/SFSDKOAuth2.m	80.62% <100.00%> (+12.73%)	⬆️

... and 35 files with indirect coverage changes

🚀 New features to boost your workflow:

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

[github-actions]

	Tests	Passed ☑️	Skipped	Failed ❌️
AuthFlowTester UI Test Results all	112 ran	62 ✅		50 ❌

Test	Result
AuthFlowTester UI Test Results all
AuthFlowTesterUITests.xctest
MultiUserLoginTests.testFlagDiversity_BeaconNonHybridJwtVsHybridOpaque()	❌ failure
MultiUserLoginTests.testBeaconAndNonBeacon_MultiUser()	❌ failure
MultiUserLoginTests.testAdvancedAuthUser_HasBWFlag_RegularAuthUser_DoesNot()	❌ failure
MultiUserLoginTests.testLogoutUserWithDynamicConfig_OtherUserUnaffected()	❌ failure
MultiUserLoginTests.testRevokeAccessForUserWithDynamicConfig_OtherUserUnaffected()	❌ failure
MultiUserLoginTests.testDifferentAppTypes_LogoutCaUser_EcaUserUnaffected()	❌ failure
MultiUserLoginTests.testFirstStatic_SecondDynamic_DifferentApps()	❌ failure
MultiUserLoginTests.testBothDynamic_DifferentApps()	❌ failure
MultiUserLoginTests.testBothStatic_SameApp_DifferentScopes()	❌ failure
MultiUserLoginTests.testFirstDynamic_SecondStatic_DifferentApps()	❌ failure
MultiUserLoginTests.testBothStatic_SameApp_SameScopes()	❌ failure
MultiUserLoginTests.test_dpopAndNonDPoPUsers_flagOff_maintainIndependentProofs()	❌ failure
MultiUserLoginTests.testDifferentAppTypes_RevokeAccessForCaUser_EcaUserUnaffected()	❌ failure
MultiUserLoginTests.testFlagDiversity_NonHybridOpaqueVsHybridJwt()	❌ failure
MultiUserLoginTests.testBothStatic_DifferentApps()	❌ failure
ECALoginTests.testECAJwt_AllScopes()	❌ failure
ECALoginTests.testECAOpaque_SubsetScopes()	❌ failure
ECALoginTests.test_givenNoDPoP_whenLoginViaPoolServer_thenSessionIsValid()	❌ failure
ECALoginTests.testECAJwt_DefaultScopes()	❌ failure
ECALoginTests.testDynamicConfigurationWithInvalidScope()	❌ failure
ECALoginTests.testECAOpaque_DefaultScopes()	❌ failure
ECALoginTests.testECAJwt_SubsetScopes()	❌ failure
ECALoginTests.testECAOpaque_AllScopes()	❌ failure
ECALoginTests.testDynamicConfigurationWithInvalidClientId()	❌ failure
RefreshTokenMigrationWithRestartTests.testMigrateBeaconScopeAddition_WithRestart()	❌ failure
RefreshTokenMigrationWithRestartTests.testMigrateScopeAddition_WithRestart()	❌ failure
RefreshTokenMigrationWithRestartTests.testMigrateCAToBeacon_WithRestart()	❌ failure
RefreshTokenMigrationWithRestartTests.testMigrateMultipleUsers_WithRestart()	❌ failure
RefreshTokenMigrationWithRestartTests.testMigrateCAToECA_WithRestart()	❌ failure
RefreshTokenMigrationTests.testMigrateCAToBeacon()	❌ failure
RefreshTokenMigrationTests.testMigrateCA_AddMoreScopes()	❌ failure
RefreshTokenMigrationTests.testMigrateCAToECA()	❌ failure
RefreshTokenMigrationTests.testMigrateBeaconOpaqueToJWTAndBack()	❌ failure
RefreshTokenMigrationTests.testMigrateCAUserAgentToECAWebServer()	❌ failure
RefreshTokenMigrationTests.testMigrateCAToBeaconAndBack()	❌ failure
RefreshTokenMigrationTests.testFlagDiversity_MigratedBeaconJwtVsNonHybridOpaque()	❌ failure
RefreshTokenMigrationTests.testMigrateBeacon_AddMoreScopes()	❌ failure
RefreshTokenMigrationTests.testMigrateOneUserOnly()	❌ failure
LegacyLoginTestsNotHybrid.testCAOpaque_SubsetScopes_WebServerFlow_InAppWebView()	❌ failure
LegacyLoginTestsNotHybrid.testCAOpaque_DefaultScopes_UserAgentFlow()	❌ failure
LegacyLoginTestsNotHybrid.testCAOpaque_AllScopes_WebServerFlow_InAppWebView()	❌ failure
LegacyLoginTestsNotHybrid.testCAOpaque_AllScopes_WebServerFlow()	❌ failure
LegacyLoginTests.testCAOpaque_DefaultScopes_WebServerFlow_InAppWebView()	❌ failure
BeaconLoginTests.testBeaconOpaque_SubsetScopes()	❌ failure
ForceAdvancedAuthTests.testForceAdvancedAuth_AddAdditionalUser_BackButtonAccessible()	❌ failure
DPoPLoginTests.test_givenDPoP_whenLoginViaPoolServer_thenTokenTypeIsDPoP()	❌ failure
DPoPLoginTests.test_givenTwoDPoPUsers_whenSwitchAndRefresh_thenTokensAndNoncesAreIsolated()	❌ failure
DPoPLoginTests.test_givenBearerSession_whenUpgradeToDPoP_thenDPoPBound()	❌ failure
LoginWithRestartTests.testBeaconJwt_SubsetScopes_DynamicConfiguration_WithRestart()	❌ failure
LoginWithRestartTests.testMultiUserRestart()	❌ failure

[sfdctaka]

LGTM!