fix(knowledge): skip verified empty Slack threads

[icecrasher321]

Summary

• Mark fully fetched Slack threads with no extractable text as skipped so connector syncs complete without scheduling empty documents.
• Remove stale indexed text when a thread becomes empty, recover when replies gain content, and retain failures for missing or incomplete responses.

Type of Change

• Bug fix

Testing

• 92 regression tests passed.
• End-to-end coverage using disposable PostgreSQL/Redis, real sync jobs, storage, indexing, and authorized search; Slack and embedding responses are synthetic.
• App type check, repo lint, API boundary validation, and all 46 audits passed.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated
docs	Skipped		Sep 10, 2026 8:55pm UTC

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge, with no outstanding correctness or repository-rule issues identified.

Summary

• Produces a replace-disposition skipped document only after all reply pages are fetched.
• Continues indexing a thread when edited replies later contain text.
• Adds connector and end-to-end regression coverage for empty, restored, incomplete, and missing-root threads.
• Changes since the previous review only reformat a test fixture insertion and introduce no behavioral differences.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Fetch all Slack reply pages] --> B{Fetch complete?}
    B -- No --> C[Fail sync and preserve existing indexed content]
    B -- Yes --> D{Root message present?}
    D -- No --> C
    D -- Yes --> E{Extractable text present?}
    E -- No --> F[Mark skipped with replace disposition]
    F --> G[Remove stale storage and searchable vectors]
    E -- Yes --> H[Fetch permalink]
    H --> I[Index or update document]

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[icecrasher321]

@greptile

[icecrasher321]

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[cubic-dev-ai]

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