fix(android): report a missing runtime dependency instead of staying silent

[posthog]

💡 Motivation and Context

• A customer lost every Android session recording for two to three months. Their build excluded com.squareup.curtains:curtains, and the SDK never told them. iOS kept recording, so the search went to Android config rather than to a missing class.
• curtains is a hard implementation dependency that three integrations need. When it is absent the SDK has two bad outcomes, neither of which names the artifact:

Where it breaks	Before	After
Integration is built (PostHogAndroid.setAndroidConfig)	NoClassDefFoundError leaves setup() uncaught	Warning names the artifact; the other integrations still install
Integration is installed (PostHog.setup loop)	Debug-only log, sessionReplayHandler never assigned	Warning names the artifact and what stays off

• The swallow was never specific to curtains: any integration that fails disappears the same way.

💚 How did you test it?

• make test and make checkFormat pass. ./gradlew apiCheck passes against the refreshed dump.
• New tests: the core install loop (PostHogIntegrationInstallFailureTest), the Android construction guard (PostHogAndroidIntegrationFailureTest), and the Logcat severity (PostHogAndroidLoggerTest — a warning reaches Logcat with debug = false, a debug message does not).
• Reproduced the real failure, not only an injected one. I removed the curtains jars from the unit-test runtime classpath and ran PostHogAndroid.setup() under Robolectric.

Reproduction on a runtime without curtains

Before, setup() does not return:

OUTCOME: setup threw java.lang.NoClassDefFoundError: curtains/OnRootViewsChangedListener

After, setup() completes and says why:

WARN: Integration PostHogReplayIntegration failed to install: java.lang.NoClassDefFoundError: curtains/OnRootViewsChangedListener. Your build excludes the 'com.squareup.curtains:curtains' artifact, which the PostHog SDK needs. Restore that artifact. Until you do, this integration and every feature that it provides stay off for the whole process.
WARN: Integration PostHogTouchActivityIntegration failed to install: java.lang.NoClassDefFoundError: curtains/TouchEventInterceptor. ...
SETUP RETURNED, integrations=[PostHogLogCatIntegration, PostHogActivityLifecycleCallbackIntegration, PostHogAppInstallIntegration, PostHogLifecycleObserverIntegration, PostHogPushSubscriptionIntegration, PostHogSendCachedEventsIntegration, PostHogErrorTrackingAutoCaptureIntegration]

The classpath filter and the probe test were scaffolding and are not in the diff.

• Not tested on a device or an emulator. No emulator was available in this environment.

Note

PostHogLogger.logWarning is a defaulted interface method that delegates to log, so a custom logger keeps its current behaviour and stays binary compatible. It is deliberately not named warn, to keep it distinct from the user-facing com.posthog.logs.PostHogLogger.warn, which sends log records to PostHog.

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm changeset to generate a changeset file

🤖 Agent context

Autonomy: Fully autonomous

• Built with Claude Opus 5 in PostHog Desktop, from the linked inbox report.
• The report located the defect in the catch (e: Throwable) of the install loop. That is real and is fixed, but a review pass found that it is not where an absent curtains first lands: all three integrations build their curtains listeners in their constructors, so the class resolves during PostHogAndroid.setAndroidConfig, before PostHog.setup(). I confirmed this in the bytecode and then in the reproduction above. Fixing only the install loop would have left the advertised warning unreachable, so the construction site is guarded too.
• Rejected along the way: making the listener fields lazy to push the failure into install() (larger, riskier, three classes); declaring the required artifact on PostHogIntegration (widens a public interface that CONTRIBUTING.md gates behind prior agreement); reusing the logs-product logger for a setup-time diagnostic (circular, and it would ship the diagnostic as customer log data).
• addIntegrationSafely is applied to every integration rather than only the curtains-backed three, so construction follows the same policy the install loop already has.

---

Created with PostHog Desktop from this inbox report.

Origin

• Conversations: ticket
• First signal: 2026-09-15
• Inbox report: open
• Likely cause: 1e14579
• Task started by: auto-start, after the report was rated P2 and ready to fix

[github-actions]

posthog-android Compliance Report

Date: 2026-10-17 01:34:01 UTC
Duration: 118473ms

✅ All Tests Passed!

46/46 tests passed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	392ms
Format Validation.Event Has Uuid	✅	27ms
Format Validation.Event Has Lib Properties	✅	29ms
Format Validation.Distinct Id Is String	✅	25ms
Format Validation.Token Is Present	✅	26ms
Format Validation.Custom Properties Preserved	✅	28ms
Format Validation.Event Has Timestamp	✅	28ms
Retry Behavior.Retries On 503	✅	7029ms
Retry Behavior.Does Not Retry On 400	✅	4026ms
Retry Behavior.Does Not Retry On 401	✅	4025ms
Retry Behavior.Respects Retry After Header	✅	7026ms
Retry Behavior.Implements Backoff	✅	17037ms
Retry Behavior.Retries On 500	✅	7020ms
Retry Behavior.Retries On 502	✅	7019ms
Retry Behavior.Retries On 504	✅	7016ms
Retry Behavior.Max Retries Respected	✅	17035ms
Deduplication.Generates Unique Uuids	✅	39ms
Deduplication.Preserves Uuid On Retry	✅	7017ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	12030ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	7020ms
Deduplication.No Duplicate Events In Batch	✅	36ms
Deduplication.Different Events Have Different Uuids	✅	24ms
Compression.Sends Gzip When Enabled	✅	18ms
Batch Format.Uses Proper Batch Structure	✅	20ms
Batch Format.Flush With No Events Sends Nothing	✅	15ms
Batch Format.Multiple Events Batched Together	✅	37ms
Error Handling.Does Not Retry On 403	✅	4020ms
Error Handling.Does Not Retry On 413	✅	4022ms
Error Handling.Retries On 408	✅	5028ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	34ms
Request Payload.Flags Request Uses V2 Query Param	✅	26ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	24ms
Request Payload.Flags Request Omits Authorization Header	✅	38ms
Request Payload.Token In Flags Body Matches Init	✅	24ms
Request Payload.Groups Round Trip	✅	24ms
Request Payload.Groups Default To Empty Object	✅	25ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	24ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	21ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	22ms
Request Lifecycle.No Flags Request On Init Alone	✅	12ms
Request Lifecycle.No Flags Request On Normal Capture	✅	28ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	49ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	29ms
Retry Behavior.Retries Flags On 502	✅	323ms
Retry Behavior.Retries Flags On 504	✅	324ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	24ms

[github-actions]

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[github-actions]

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