fix(slack): preserve text order around tool progress

[TheodoreSpeaks]

Summary

• Flush buffered answer text before starting a visible Slack tool task so progress cards cannot split a sentence.
• Serialize stream events and wait for pending delivery before finishing. Preparatory and hidden tool events no longer insert paragraph breaks.
• Keep tool cards at their original text boundaries when secret projection or citation evidence delays delivery; failure cleanup includes only tasks already sent or attempted.

Type of Change

• Bug fix

Testing

86 focused tests passed, including sentence ordering, concurrent events, deferred secret projection and citations, cancellation, delivery failures, and connection controls. App typecheck, lint, all 46 repository audits, block registry, and docs manifest checks passed. Verified the response and native tool progress order in a live Slack DM.

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 5:28am UTC

[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge; no actionable new issue or outstanding previous finding remains.

Summary

• Flushes safe preceding text before delivering a tool task.
• Defers tasks when secret projection or citation evidence withholds preceding text.
• Tracks only delivered or attempted tasks for failure cleanup.
• Adds focused coverage for deferred projection, citations, cancellation, concurrent events, and ambiguous delivery failures.
• The previously reported progress-overtaking issue is fixed, and its thread was manually resolved.

Diagram

sequenceDiagram
    participant O as Orchestrator
    participant S as SlackSearchAssistantStream
    participant P as Projection
    participant A as Slack API

    O->>S: Assistant text
    S->>S: Buffer text
    O->>S: Visible tool call
    S->>S: Queue task at text boundary
    S->>P: Project preceding text
    alt Prefix is stable and safe
        S->>A: Append preceding text
        S->>A: Append task update
        S->>A: Append following text
    else Secret or citation remains unresolved
        S->>A: Append only safe prefix
        S->>S: Retain queued task
        O->>S: Evidence or completion
        S->>P: Re-project text
        S->>A: Append remainder, task, and later text
    end

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[TheodoreSpeaks]

@greptile