chore: improved backfill speed, notably when unblocking a user

[highesttt]

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[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between e1fd206 and 11fc156.

📒 Files selected for processing (2)

• pkg/connector/client.go
• pkg/connector/sync.go

📜 Recent review details

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**/*.go

📄 CodeRabbit inference engine (AGENTS.md)

**/*.go: Use go fmt for code formatting across all Go files
Use goimports with -local "github.com/highesttt/matrix-line-messenger" flag to group project-local imports correctly
Use zerolog for logging throughout the codebase
Do not use Msgf in logging; use Msg with structured fields instead
Use Stringer interface where applicable in Go code

Files:

• pkg/connector/client.go
• pkg/connector/sync.go

**/!(ltsm)/**/*.go

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**/!(ltsm)/**/*.go: Run staticcheck on all Go files excluding pkg/ltsm package (transpiled WASM code)
Run go vet on all Go files excluding pkg/ltsm package (transpiled WASM code)

Files:

• pkg/connector/client.go
• pkg/connector/sync.go

🔇 Additional comments (9)

pkg/connector/sync.go (8)

27-27: LGTM!

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29-53: LGTM!

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91-91: LGTM!

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95-148: LGTM!

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254-296: LGTM!

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764-771: LGTM!

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867-882: LGTM!

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150-155: LGTM!

pkg/connector/client.go (1)

280-283: LGTM!

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Improved reliability of blocked-contact synchronization during connection
  • Enhanced DM chat recovery and backfilling behavior
  • Optimized message prefetching with concurrent processing for faster startup

Walkthrough

The PR refactors blocked-contact fetching and DM synchronization in the LINE connector. A new refreshBlockedContacts helper centralizes blocked-contact retrieval and cache updates, integrating into Connect and fullSync. DM chat resync and backfill unify into a single call with a forceBackfill flag, simplifying the unblock flow. Startup message prefetch switches from serial to bounded-concurrency workers.

Changes

Blocked Contact Refresh and DM Sync Optimization

Layer / File(s)	Summary
Blocked contacts refresh helper and integration pkg/connector/sync.go, pkg/connector/client.go	New refreshBlockedContacts fetches blocked contact IDs from LINE with token recovery, converts them to a cached lookup map, and is called from both Connect startup and fullSync sync polling.
DM chat resync with unified forced backfill pkg/connector/sync.go	queueDMChatResync accepts a new forceBackfill parameter, wiring ChatInfo.CanBackfill and optionally forcing immediate backfill. OpUnblockContact now makes a single resync call with forced backfill instead of separate queue operations.
Message prefetch concurrency optimization pkg/connector/sync.go	prefetchMessages switches from serial to bounded worker pool with configurable concurrency, skips blocked users, and respects context cancellation.

🎯 2 (Simple) | ⏱️ ~12 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	No description was provided by the author, which is a missing required element.	Add a pull request description explaining the motivation, approach, and any testing performed for the backfill speed improvements.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: improved backfill speed optimization, particularly when unblocking a user.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch backfill-speed-improvements

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