perf: skip sanitizing trusted render spans

[benvinegar]

Summary

• mark Pierre-built render spans as terminal-safe after source text is normalized
• skip repeated span sanitization for those trusted spans while keeping external/test-authored spans on the safe path
• clear the trust marker when merged spans mix safe and untrusted text

Validation

• bun test src/lib/terminalText.test.ts src/ui/diff/pierre.test.ts src/ui/lib/ui-lib.test.ts
• bun run typecheck

This PR description was generated by Pi using OpenAI GPT-5

[greptile-apps]

Greptile Summary

This PR introduces a terminalSafe trust marker on RenderSpan to skip redundant sanitizeTerminalLine calls for spans that were already normalized by Pierre's pipeline. The invariant is correctly founded: tabify() (called by both flattenHighlightedLine and cleanDiffLine) internally calls sanitizeTerminalLine, so every Pierre-built span is already clean. mergeSpan and appendRenderSpan both correctly clear the marker when safe and untrusted spans are coalesced.

• Adds terminalSafe?: true to RenderSpan and propagates it through the two merge helpers; the merge logic correctly demotes the flag to undefined on mixed-trust concatenation.
• sanitizeTerminalSpans short-circuits for trusted spans; untrusted (external/test-authored) spans still run the full sanitization path.
• spansForHighlightedSourceLine — used for expanded context rows — has two fallback paths that call cleanDiffLine but do not set terminalSafe: true, leaving the optimization incomplete for that code path.

Confidence Score: 4/5

Safe to merge; the trust invariant is correctly established because tabify() calls sanitizeTerminalLine internally, so all Pierre-built spans are genuinely clean before the marker is applied.

The core optimization is sound. The only gap is that spansForHighlightedSourceLine — used for expanded context rows — has two fallback paths that produce terminal-safe text via cleanDiffLine but do not stamp terminalSafe: true, so those spans will continue to be re-sanitized on every render. This is a missed optimization rather than incorrect behavior.

The two fallback return sites in spansForHighlightedSourceLine in src/ui/diff/pierre.ts (around lines 727–737) are the only spots that did not receive the terminalSafe: true treatment applied everywhere else in this PR.

Important Files Changed

Filename	Overview
src/lib/terminalText.ts	Adds trusted-span fast path to sanitizeTerminalSpans; the generic cast and runtime property check are safe in practice. Unsanitized spans correctly receive terminalSafe: undefined on the slow path.
src/ui/diff/pierre.ts	Marks terminalSafe: true in flattenHighlightedLine and both fallback paths inside makeSplitCell/makeStackCell; the analogous fallback in spansForHighlightedSourceLine (context rows) is not marked.
src/ui/diff/renderRows.tsx	Adds terminalSafe propagation to appendRenderSpan; the merge logic is consistent with the equivalent change in pierre.ts.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["Raw diff line / HAST node"] --> B["cleanDiffLine\n(tabify → sanitizeTerminalLine)"]
    A --> C["flattenHighlightedLine\n(tabify → sanitizeTerminalLine)"]
    B --> D["RenderSpan\nterminalSafe: true ✓"]
    C --> D
    D --> E["mergeSpan / appendRenderSpan"]
    E -- "both safe" --> F["merged span\nterminalSafe: true ✓"]
    E -- "mixed trust" --> G["merged span\nterminalSafe: undefined"]
    F --> H["sanitizeTerminalSpans"]
    G --> H
    H -- "terminalSafe: true" --> I["fast path: push ref,\nskip sanitizeTerminalLine"]
    H -- "no marker" --> J["slow path: run\nsanitizeTerminalLine"]
    I --> K["sliceSpansWindow / wrapSpans\n(new objects via spread)"]
    J --> K
    K --> L["renderInlineSpans → terminal output"]
    M["spansForHighlightedSourceLine\nfallback (context rows)"] -- "missing terminalSafe ⚠" --> J

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Comments Outside Diff (1)

1. src/ui/diff/pierre.ts, line 726-737 (link)

   The two fallback paths in spansForHighlightedSourceLine call cleanDiffLine — which internally runs tabify → sanitizeTerminalLine — so the resulting text is already terminal-safe, but neither span is stamped with terminalSafe: true. Every render of an expanded context row whose highlighted line is missing will re-run sanitizeTerminalLine unnecessarily, while the parallel paths in makeSplitCell and makeStackCell are already optimised. The fix is the same two-character addition used elsewhere in this PR.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: src/ui/diff/pierre.ts
   Line: 726-737
   
   Comment:
   The two fallback paths in `spansForHighlightedSourceLine` call `cleanDiffLine` — which internally runs `tabify` → `sanitizeTerminalLine` — so the resulting text is already terminal-safe, but neither span is stamped with `terminalSafe: true`. Every render of an expanded context row whose highlighted line is missing will re-run `sanitizeTerminalLine` unnecessarily, while the parallel paths in `makeSplitCell` and `makeStackCell` are already optimised. The fix is the same two-character addition used elsewhere in this PR.
   
   
   
   How can I resolve this? If you propose a fix, please make it concise.

   Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
src/ui/diff/pierre.ts:726-737
The two fallback paths in `spansForHighlightedSourceLine` call `cleanDiffLine` — which internally runs `tabify` → `sanitizeTerminalLine` — so the resulting text is already terminal-safe, but neither span is stamped with `terminalSafe: true`. Every render of an expanded context row whose highlighted line is missing will re-run `sanitizeTerminalLine` unnecessarily, while the parallel paths in `makeSplitCell` and `makeStackCell` are already optimised. The fix is the same two-character addition used elsewhere in this PR.

```suggestion
  if (highlightedLine === undefined) {
    const fallbackText = cleanDiffLine(rawLine);
    return fallbackText.length > 0 ? [{ text: fallbackText, terminalSafe: true }] : [];
  }

  const spans = flattenHighlightedLine(highlightedLine, theme, theme.contextContentBg);
  if (spans.length > 0) {
    return spans;
  }

  const fallbackText = cleanDiffLine(rawLine);
  return fallbackText.length > 0 ? [{ text: fallbackText, terminalSafe: true }] : [];
```

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