feat(sqs): triggers own subscription config so spread needs no workarounds

[kibertoad]

Problem

Spreading a pre-resolved consumer-options object (e.g. @lokalise/aws-config's resolveConsumerOptions(...)) into a trigger source forced callers to hand-unset fields the resolver had computed for a real consumer. Real-world call sites looked like this:

sources: [{
  creationConfig: { ... },
  ...resolvedOptions,
  // resolveConsumerOptions derives the filter policy from handlers, but the
  // trigger builds its own handlers from bindings. Empty handlers => reject-all,
  // so we reset Attributes here to accept all messages.
  subscriptionConfig: { updateAttributesIfExists: ... },
  // The resolver sets subscriptionDeadLetterQueue; we override it to undefined to
  // avoid a second Subscribe conflicting with the updated attributes.
  subscriptionDeadLetterQueue: undefined,
}]

Root cause: a trigger is not a plain consumer — it owns its handlers and its subscription filtering — but it blindly spread a full consumer's options, leaving callers to un-set everything that didn''t apply.

Changes

A. Fix the double-init in AbstractSqsTrigger. It called c.init() and c.start(), but the underlying message-queue-toolkit consumer''s start() already runs init() internally — so every consumer initted twice, and the second pass re-subscribed each queue, conflicting with the subscription attributes (filter policy, redrive policy) set on the first pass. Now it only calls start().

B. The trigger claims only what it truly owns, centrally. buildSnsTriggerConsumerOptions resets:

• handlers — always rebuilt from bindings.
• subscription filter policy (subscriptionConfig.Attributes.FilterPolicy / FilterPolicyScope) — dropped (the reject-all policy the resolver derives from empty handlers); defaults to accept-all.

Everything else flows through, including the subscription-level DLQ. Since fix A removes the double-init conflict, there''s no longer any reason to strip it: subscriptionConfig.Attributes.RedrivePolicy (the subscription DLQ in the installed toolkit) is preserved alongside any other attributes, and a spread-in subscriptionDeadLetterQueue (used by resolveConsumerOptions / newer toolkits) flows through to the consumer.

Shared by the flat and group SNS triggers, and exported. SQS-queue triggers were already lifecycle-only and gain fix A for free.

After this, the call site is just ...resolvedOptions + creationConfig + bindings — no subscriptionConfig patch, no subscriptionDeadLetterQueue override, no Attributes reset.

Tests

New test/triggerInternals.spec.ts (8 deterministic unit tests): the option sanitizer (handler injection, FilterPolicy/FilterPolicyScope drop, RedrivePolicy preserved, subscriptionDeadLetterQueue forwarded, updateAttributesIfExists default/override, pass-through of unrelated options) and the lifecycle fix (each consumer start()ed exactly once, init() never called separately; stop() closes all). Full suite: 42 passed, no type errors.

🤖 Generated with Claude Code

[coderabbitai]

📝 Walkthrough

Walkthrough

Extracts SNS→SQS consumer option normalization into a new exported buildSnsTriggerConsumerOptions helper that strips subscription-level DLQ, filter-policy Attributes, and forces updateAttributesIfExists: false. Removes the duplicate init() call from AbstractSqsTrigger.start(). Both flat and group invalidation triggers are refactored to use the helper. Adds unit tests and updates README docs.

Changes

SNS Trigger Consumer Options Refactor and Lifecycle Fix

Layer / File(s)	Summary
AbstractSqsTrigger lifecycle fix packages/sqs/lib/triggers/AbstractSqsTrigger.ts, packages/sqs/test/triggerInternals.spec.ts	Removes the explicit init() call per consumer from start(), relying on the consumer's own start() for initialization. Tests assert each handle's start() is called exactly once with no direct init(), and stop() closes all handles.
buildSnsTriggerConsumerOptions helper packages/sqs/lib/triggers/SnsTopicInvalidationTrigger.ts, packages/sqs/index.ts	New exported helper normalizes SNSSQSConsumerOptions: strips subscriptionDeadLetterQueue, removes subscriptionConfig.Attributes, forces updateAttributesIfExists: false, and injects bindings-derived handlers and messageTypeResolver. Re-exported from the package index.
Flat and group triggers refactored packages/sqs/lib/triggers/SnsTopicInvalidationTrigger.ts, packages/sqs/lib/triggers/SnsTopicGroupInvalidationTrigger.ts	buildConsumer in both triggers delegates option assembly to buildSnsTriggerConsumerOptions, removing inline assembly of handlers, messageTypeResolver, and subscriptionConfig defaults. Group trigger imports updated accordingly.
Tests and docs packages/sqs/test/triggerInternals.spec.ts, packages/sqs/README.md	triggerInternals.spec.ts covers all normalization behaviors of the helper. README clarifies which consumer options are trigger-owned versus passed through unchanged.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• kibertoad/layered-loader#389: Introduced the AbstractSqsTrigger and SNS-topic trigger plumbing that this PR's lifecycle fix and helper extraction directly build upon.
• kibertoad/layered-loader#404: Added the "spread full consumer options" behavior in SnsTopicInvalidationTrigger.ts that this PR further normalizes by centralizing option assembly into buildSnsTriggerConsumerOptions.

Suggested labels

minor

Suggested reviewers

• armababy
• kosmos2uh
• CarlosGamero

Poem

🐇 A rabbit refactored with glee,
Two triggers now share a helper, you see!
No double init() to fret,
The DLQ fields — stripped and unset,
Subscriptions flow cleanly and free! 🎉

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately reflects the main change: introducing a mechanism for triggers to own subscription configuration, eliminating the need for spread-based workarounds.
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/trigger-owns-subscription-config

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