improvement(patch): append, patch snapshot based streaming

[icecrasher321]

Summary

Classify the stream by operation instead of by prefix:

• append / patch → complete full-file snapshots → applied live. Each setContent is a localized change that ProseMirror diffs in place (no collapse, no flicker).
• create / update → streamed from scratch → keep the existing guard: reveal while it extends from empty, hold a rewrite until settle (prevents the original collapse flicker).

Type of Change

• Other: UX Improvement

Testing

Tested manually

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 (UTC)
docs	Skipped		Jun 21, 2026 2:03am

[cursor]

PR Summary

Low Risk
Scoped UX change to agent streaming preview in the markdown editor; no auth, persistence, or API changes.

Overview
Agent file previews now distinguish append/patch from create/update when syncing streamed markdown into the rich editor.

A new streamIsIncremental flag is derived in mothership ResourceContent from previewSession.operation (append or patch) and passed through FileViewer into RichMarkdownEditor. For incremental ops, each chunk is a full-file snapshot built on the existing doc, so the streaming RAF tick always applies updates instead of requiring the text to prefix-extend what’s on screen. Create/update streams still use the old guard: only reveal while the payload extends the current body, and hold rewrites until settle to avoid collapse/flicker.

The editor keeps the flag in a ref so in-flight ticks see the latest edit kind if the operation changes mid-turn.

^{Reviewed by Cursor Bugbot for commit 267d7d5. Configure here.}

[greptile-apps]

Greptile Summary

This PR adds a streamIsIncremental flag that classifies streaming by operation type (append/patch = incremental snapshots, create/update = from-scratch rebuilds) and passes it through the component tree to the markdown editor's streaming RAF tick.

• Incremental path: For append/patch, the "hold until content extends shown" guard is bypassed — every complete snapshot is applied live via setContent, letting ProseMirror diff localized changes without flicker.
• Rebuild path: For create/update, the original guard is preserved — chunks are only revealed while they extend what is shown, preventing the collapse flicker on partial rewrites.
• The new streamIsIncrementalRef pattern correctly reads the latest value inside the RAF tick, handling same-turn operation transitions (e.g. append followed by a rewrite).

Confidence Score: 5/5

Safe to merge — the change is narrowly scoped to the markdown editor's streaming tick and does not touch any data-persistence, authentication, or API paths.

The logic is self-contained: a single boolean flag read via a ref inside a RAF tick, guarded only on the RAF path (never affecting settle or persistence). The ref pattern is correct for this async context. The settle path is unchanged and acts as a safety net regardless of operation type, ensuring the final server-persisted content is always applied. No edge cases found that would lead to incorrect document state.

No files require special attention. rich-markdown-editor.tsx carries the most logic, but the change is well-isolated to the existing streaming tick.

Important Files Changed

Filename	Overview
apps/sim/app/workspace/[workspaceId]/home/components/mothership-view/components/resource-content/resource-content.tsx	Derives streamIsIncremental from previewSession?.operation and threads it to both the synthetic streaming-file path and the EmbeddedFile path. Logic is correct — undefined/create/update all produce false.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/file-viewer.tsx	Pure prop pass-through to RichMarkdownEditor; no logic change.
apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/rich-markdown-editor.tsx	Core change: stores streamIsIncremental in a ref so the RAF tick always reads the latest value; the hold guard is now conditioned on !streamIsIncrementalRef.current && !extendsShown. Settle path is unchanged and correctly applies the final content regardless of operation type.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant RC as ResourceContent
    participant FV as FileViewer
    participant LME as LoadedRichMarkdownEditor
    participant RAF as RAF tick

    RC->>RC: "operation == append|patch → streamIsIncremental=true"
    RC->>FV: streamIsIncremental
    FV->>LME: streamIsIncremental
    LME->>LME: "streamIsIncrementalRef.current = streamIsIncremental"

    alt "append / patch (incremental)"
        LME->>RAF: "arm tick with new snapshot"
        RAF->>RAF: "streamIsIncrementalRef=true, skip hold guard"
        RAF->>LME: "setContent(snapshot) live apply"
    else "create / update (rebuild)"
        LME->>RAF: "arm tick with new chunk"
        RAF->>RAF: "extendsShown=false, streamIsIncremental=false, hold"
        RAF-->>LME: "held until settle"
    end

    LME->>LME: "settle: cancel RAF, apply final body if differs"

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sequenceDiagram
    participant RC as ResourceContent
    participant FV as FileViewer
    participant LME as LoadedRichMarkdownEditor
    participant RAF as RAF tick

    RC->>RC: "operation == append|patch → streamIsIncremental=true"
    RC->>FV: streamIsIncremental
    FV->>LME: streamIsIncremental
    LME->>LME: "streamIsIncrementalRef.current = streamIsIncremental"

    alt "append / patch (incremental)"
        LME->>RAF: "arm tick with new snapshot"
        RAF->>RAF: "streamIsIncrementalRef=true, skip hold guard"
        RAF->>LME: "setContent(snapshot) live apply"
    else "create / update (rebuild)"
        LME->>RAF: "arm tick with new chunk"
        RAF->>RAF: "extendsShown=false, streamIsIncremental=false, hold"
        RAF-->>LME: "held until settle"
    end

    LME->>LME: "settle: cancel RAF, apply final body if differs"

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_{Reviews (1): Last reviewed commit: "improvement(path): append, patch snapsho..." | Re-trigger Greptile}