[NO QA] Adds logging to MFA flow by dariusz-biela · Pull Request #84058 · Expensify/App

dariusz-biela · 2026-03-03T17:55:54Z

Explanation of Change

Adds observability instrumentation to the MFA and 3DS transaction authorization flows. This includes:

Sentry breadcrumbs throughout the MFA flow lifecycle (flow start, registration/authorization challenges, biometric results, backend responses, errors, cancellations) and 3DS navigation/authorization pages
MFA flow outcome tracking via trackMfaFlowOutcome — sends a Sentry.captureMessage event plus Log.info/Log.hmmm calls on every flow completion (success or failure), with full context (scenario, reason, httpStatusCode, auth method, state flags)
New telemetry constants — breadcrumb categories (mfa, 3ds.navigation, 3ds.authorize) and Sentry tags (mfa_scenario, mfa_error_reason)
scenarioName added to MFA state so the outcome tracker knows which scenario was executed (preserved across re-registrations)
message field added to RegistrationChallengeResponse and AuthenticationChallengeResponse types for richer error context

Known limitations (to be addressed in follow-up work)

Sentry data scrubbing — Sentry is configured to scrub values containing keywords like authorization, authenticated, credential, key, secret, signature, token, etc. This causes many MFA-related error details to be redacted because they naturally contain words like "authorization". Needs investigation into adjusting the Sentry blocklist configuration.
Sentry event deduplication / rate limiting — If a user hits the same failure (e.g. "MFA Flow Error") multiple times in a row, Sentry deduplicates and only captures the first occurrence. This means repeated failures from the same user may be underreported.
Messages vs Logs — Currently all instrumentation uses Sentry.captureMessage + breadcrumbs. Sentry also supports lightweight Logs (simple messages without accumulated breadcrumb context). Some of the current instrumentation could be moved to Logs for lower overhead, while keeping captureMessage only for cases where full breadcrumb context is valuable.

Fixed Issues

$ #82705

Tests

N/A — This is a logging/observability-only change. No user-facing behavior is modified.

Verify that no errors appear in the JS console

Offline tests

N/A — No offline behavior changes. MFA breadcrumbs and Sentry events are fire-and-forget; they do not affect offline functionality.

QA Steps

N/A — No user-facing behavior changes. This PR only adds internal logging and Sentry instrumentation.

Verify that no errors appear in the JS console

PR Author Checklist

Screenshots/Videos

Adds breadcrumb tracing at key decision points in the MFA state machine to provide a chronological trail in Sentry when issues occur in production (failed biometrics, stuck flows, backend errors).

Add breadcrumbs to the navigation hook and authorize transaction page with separate categories (3ds.navigation, 3ds.authorize) for filtering. Inline breadcrumb helpers directly in consuming files.

codecov · 2026-03-03T18:21:39Z

Codecov Report

❌ Looks like you've decreased code coverage for some files. Please write tests to increase, or at least maintain, the existing level of code coverage. See our documentation here for how to interpret this table.

Files with missing lines	Coverage Δ
src/CONST/index.ts	`94.30% <ø> (ø)`
.../MultifactorAuthentication/Context/stateReducer.ts	`26.19% <ø> (ø)`
...ibs/MultifactorAuthentication/Biometrics/VALUES.ts	`100.00% <100.00%> (ø)`
...rc/libs/actions/MultifactorAuthentication/index.ts	`9.63% <ø> (ø)`
...ifactorAuthentication/observability/breadcrumbs.ts	`0.00% <0.00%> (ø)`
...vigation/useNavigateTo3DSAuthorizationChallenge.ts	`67.74% <0.00%> (-4.68%)`	⬇️
...rAuthentication/AuthorizeTransactionPage/index.tsx	`0.00% <0.00%> (ø)`
...uthentication/observability/trackMFAFlowOutcome.ts	`0.00% <0.00%> (ø)`
...ponents/MultifactorAuthentication/Context/Main.tsx	`2.80% <0.00%> (-0.67%)`	⬇️
... and 187 files with indirect coverage changes

Resolve conflict in CONST/index.ts — keep both MFA/3DS breadcrumb categories and new module.init/script.load categories from main.

melvin-bot · 2026-03-04T18:46:47Z

@dukenv0307 Please copy/paste the Reviewer Checklist from here into a new comment on this PR and complete it. If you have the K2 extension, you can simply click: [this button]

rafecolton

Prefer MFA everywhere to Mfa, since it is an acronym.

rafecolton · 2026-03-04T20:54:21Z

src/components/MultifactorAuthentication/observability/trackMfaFlowOutcome.ts

+import type {AuthTypeName, MultifactorAuthenticationReason} from '@libs/MultifactorAuthentication/Biometrics/types';
+import CONST from '@src/CONST';
+
+const EXPECTED_FAILURE_REASONS = new Set<MultifactorAuthenticationReason>([


From the context, specifically not seeing "already reviewed" in this list, I think I know what you mean by expected vs unexpected. However, it's a bit of an overloaded term, since there are actually more like three types in this regard:

Errors that are known and we think the user is likely to encounter

Errors that are known and we think the user is not likely to encounter

Errors that are not known (e.g. 5xx)

My suggestion is:

Rename EXPECTED_FAILURE_REASONS to ROUTINE_FAILURES. Then category (2) above can be ANOMALOUS_FAILURES, and (3) is UNCLASSIFIED_FAILURES.

Create a sub-grouping within the type definitions so you can pull that directly and don't need to duplicate it here. This can be in addition or perhaps instead of the existing groupings e.g. CHALLENGE, EXPO, etc.

rafecolton · 2026-03-04T20:55:59Z

src/components/MultifactorAuthentication/observability/trackMfaFlowOutcome.ts

+
+function trackMfaFlowOutcome(context: MfaFlowOutcomeContext): void {
+    try {
+        const isExpectedFailure = !context.isSuccessful && context.reason !== undefined && EXPECTED_FAILURE_REASONS.has(context.reason);


Per above comment, I suggest renaming this to isRoutineFailure

rafecolton · 2026-03-04T20:58:39Z

src/components/MultifactorAuthentication/observability/trackMfaFlowOutcome.ts

+        });
+
+        if (level === 'error') {
+            Log.hmmm(`[MFA] ${eventMessage}`, extra);


Let's use warn here so that if we get a lot for the same reason, it'll trigger a bugbot

rafecolton · 2026-03-04T21:00:45Z

src/pages/MultifactorAuthentication/AuthorizeTransactionPage/index.tsx

    };

    const onSilentlyDenyTransaction = () => {
+        addBreadcrumb('Silent deny (back button)', {transactionID}, 'warning');


NAB "back button" could get confused with the browser back button

Suggested change

addBreadcrumb('Silent deny (back button)', {transactionID}, 'warning');

addBreadcrumb('Silent deny (user canceled flow)', {transactionID}, 'warning');

…lds, add Sentry fingerprint by reason

…in VALUES.ts

…gbot

rafecolton

You have some CI failures, otherwise LGTM

…ILURES sets tsgo infers narrow literal unions for Set elements, causing .has() to reject the wider MultifactorAuthenticationReason type. Adding an explicit ReasonValue type parameter to both sets resolves the mismatch.

rafecolton

Thank you! @chuckdries final review is yours

chuckdries · 2026-03-06T18:46:35Z

src/libs/Navigation/useNavigateTo3DSAuthorizationChallenge.ts


            if (cancel) {
                Log.info('[useNavigateTo3DSAuthorizationChallenge] Ignoring navigation - effect was cleaned up while GetTransactionsPending3DSReview was in-flight');
+                addBreadcrumb('Skipped - effect cancelled', {transactionID: transactionPending3DSReview.transactionID});


Looks good overall, but now that we have the breadcrumb is there a reason to keep the logs that say the same thing?

github-actions · 2026-03-09T20:09:54Z

🚧 @rafecolton has triggered a test Expensify/App build. You can view the workflow run here.

chuckdries · 2026-03-09T20:39:03Z

Reviewer Checklist

I have verified the author checklist is complete (all boxes are checked off).
I verified the correct issue is linked in the ### Fixed Issues section above
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- I verified the steps for local testing are in the Tests section
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- I verified the steps cover any possible failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
- I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
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I verified tests pass on all platforms & I tested again on:
- Android: HybridApp
- Android: mWeb Chrome
- iOS: HybridApp
- iOS: mWeb Safari
- MacOS: Chrome / Safari
If there are any errors in the console that are unrelated to this PR, I either fixed them (preferred) or linked to where I reported them in Slack
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- I verified any copy / text shown in the product is localized by adding it to src/languages/* files and using the translation method
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- I verified proper file naming conventions were followed for any new files or renamed files. All non-platform specific files are named after what they export and are not named "index.js". All platform-specific files are named for the platform the code supports as outlined in the README.
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Screenshots/Videos

iOS: HybridApp

MacOS: Chrome / Safari

github-actions · 2026-03-09T21:13:03Z

🚧 @chuckdries has triggered a test Expensify/App build. You can view the workflow run here.

github-actions · 2026-03-09T21:18:04Z

🧪🧪 Use the links below to test this adhoc build on Android, iOS, and Web. Happy testing! 🧪🧪
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OSBotify · 2026-03-09T21:27:19Z

🚀 Deployed to staging by https://github.com/chuckdries in version: 9.3.34-0 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅

OSBotify · 2026-03-10T18:49:25Z

🚀 Deployed to production by https://github.com/luacmartins in version: 9.3.34-2 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅

dariusz-biela added 6 commits March 3, 2026 16:01

Add Sentry breadcrumbs to MFA module for production observability

c915b9a

Adds breadcrumb tracing at key decision points in the MFA state machine to provide a chronological trail in Sentry when issues occur in production (failed biometrics, stuck flows, backend errors).

Enrich Flow started breadcrumb with device and registration context

245457a

Add Sentry breadcrumbs to 3DS transaction authorization flow

4f21ee9

Add breadcrumbs to the navigation hook and authorize transaction page with separate categories (3ds.navigation, 3ds.authorize) for filtering. Inline breadcrumb helpers directly in consuming files.

Add Sentry events for MFA flow outcome tracking

ed6c50f

Add Log.info and Log.hmmm calls to MFA flow outcome tracking

890dd91

Add scenarioName to MFA state for accurate outcome tracking

a638527

melvin-bot bot assigned dariusz-biela Mar 3, 2026

rafecolton mentioned this pull request Mar 3, 2026

[ECUK/EU][In-App 3DS] Add logging and instrumentation #82705

Open

1 task

dariusz-biela added 2 commits March 4, 2026 14:54

Move Sentry.captureMessage before Log calls in MFA outcome tracking

6b63075

Merge main into dariusz-biela/feat/3ds/obsevability

91998c7

Resolve conflict in CONST/index.ts — keep both MFA/3DS breadcrumb categories and new module.init/script.load categories from main.

dariusz-biela marked this pull request as ready for review March 4, 2026 18:46

dariusz-biela requested review from a team as code owners March 4, 2026 18:46

melvin-bot bot requested review from dukenv0307 and removed request for a team March 4, 2026 18:46

melvin-bot bot requested review from JmillsExpensify and removed request for a team March 4, 2026 18:46

Fix spellcheck: typeguard → type guard

4b971b5

rafecolton removed request for JmillsExpensify and dukenv0307 March 4, 2026 20:40

rafecolton requested changes Mar 4, 2026

View reviewed changes

dariusz-biela added 5 commits March 5, 2026 13:24

Refactor trackMfaFlowOutcome: separate scenarioResponse and error fie…

a1b7f07

…lds, add Sentry fingerprint by reason

Rename Mfa to MFA in observability code

a4ae432

Classify MFA failures as routine/anomalous/unclassified, define sets …

ff86e69

…in VALUES.ts

Use Log.warn instead of Log.hmmm for MFA error outcomes to trigger bu…

ee0146c

…gbot

Clarify silent deny breadcrumb: back button → user canceled flow

a6019f3

dariusz-biela requested a review from rafecolton March 5, 2026 13:57

Split failure classification comment into separate JSDoc per set

87ba461

rafecolton previously approved these changes Mar 6, 2026

View reviewed changes

dariusz-biela dismissed rafecolton’s stale review via 69f5e42 March 6, 2026 10:04

rafecolton approved these changes Mar 6, 2026

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chuckdries reviewed Mar 6, 2026

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rafecolton requested a review from DylanDylann March 9, 2026 20:12

chuckdries approved these changes Mar 9, 2026

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chuckdries merged commit edbd8e2 into Expensify:main Mar 9, 2026
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OSBotify mentioned this pull request Mar 9, 2026

Deploy Checklist: New Expensify 2026-03-09 #84634

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	addBreadcrumb('Silent deny (back button)', {transactionID}, 'warning');
	addBreadcrumb('Silent deny (user canceled flow)', {transactionID}, 'warning');

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Explanation of Change

Known limitations (to be addressed in follow-up work)

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dariusz-biela commented Mar 3, 2026 •

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