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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Jun 10, 2026 7:32pm

PR Summary

Low Risk
Preview-only UI behavior in the file viewer; no auth, API, or data-path changes.

Overview
Fixes streamed markdown file previews replaying the per-character fade on text that is already on screen—especially during patch/in-place rewrites and scroll-driven re-renders.

useStreamAnimationGate turns Streamdown’s char animation on only for from-scratch streams (streaming starts with content length ≤ RESUME_SKIP_THRESHOLD, now exported from use-smooth-text so pacing and animation agree). The gate turns off when content updates are not appends (new string doesn’t start with the previous one), matching snapOnNonAppend behavior on smooth text reveal.

STREAMDOWN_ALLOWED_TAGS is a stable module-level allowedTags object instead of an inline literal, avoiding unnecessary identity churn on re-render.

^{Reviewed by Cursor Bugbot for commit 36ff136. Configure here.}

Greptile Summary

This PR fixes two sources of spurious re-animation in the file-preview panel: an unstable allowedTags object identity that caused Streamdown to re-render on every tick, and the per-character fade-in being applied to already-visible text during scroll-based re-renders or in-place patch rewrites.

• STREAMDOWN_ALLOWED_TAGS is hoisted to module scope so the prop identity is stable across renders, eliminating unnecessary Streamdown remounts.
• useStreamAnimationGate gates the STREAM_ANIMATION object to only fresh, from-scratch streams by tracking the isStreaming transition and latching off when a non-append content rewrite is detected mid-stream.
• RESUME_SKIP_THRESHOLD is exported from use-smooth-text.ts so both the smooth-text hook and the new gate hook agree on what counts as "pre-existing" content.

Confidence Score: 5/5

Safe to merge — both changes are narrowly scoped to the file-preview streaming animation path and carry no risk to data or state persistence.

The STREAMDOWN_ALLOWED_TAGS hoisting is a straightforward referential-stability fix. The useStreamAnimationGate hook follows the same render-phase ref-mutation pattern already used by useSmoothText, the threshold is shared correctly via the new export, and the latch-off logic mirrors the snapOnNonAppend guard already in the smooth-text hook. No new state, no new network calls, and the change only affects animation — the worst case is a missing fade-in, not broken content.

No files require special attention.

Important Files Changed

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[New render: content, isStreaming] --> B{isStreaming changed?}
    B -- yes --> C{isStreaming = true AND\ncontent.length <= RESUME_SKIP_THRESHOLD?}
    C -- yes --> D[animateRef = true\nfresh stream from scratch]
    C -- no --> E[animateRef = false\nresume / pre-existing doc]
    B -- no --> F{isStreaming=true AND\nanimateRef=true AND\nnon-append content change?}
    F -- yes --> G[animateRef = false\npatch/rewrite detected — latch off]
    F -- no --> H[animateRef unchanged]
    D --> I[return isStreaming AND animateRef]
    E --> I
    G --> I
    H --> I
    I --> J{shouldAnimateStream?}
    J -- true --> K[Streamdown: animated=STREAM_ANIMATION]
    J -- false --> L[Streamdown: animated=false]

_{Reviews (1): Last reviewed commit: "fix(file-preview): gate streaming animat..." | Re-trigger Greptile}