Greptile Summary

This PR is a clean refactoring that introduces src/core/constants.ts as the single source of truth for diff, layout, scroll, watch, and theme constants previously scattered as inline literals across five files. No logic is changed — every replacement is a direct 1-to-1 substitution with an identically-valued named constant.

Key changes:

• DIFF_CONTEXT_LINES = 3 replaces two hardcoded 3 literals in loaders.ts, keeping parseDiffFromFile and createTwoFilesPatch in sync
• UI_LAYOUT_CONSTANTS (6 values) replaces local const declarations inside AppShell, and introduces the previously unnamed SIDEBAR_DEFAULT_WIDTH = 34
• UI_SCROLL_CONSTANTS (4 values) replaces inline numbers in DiffPane and VerticalScrollbar; the SCROLL_RESTORE_RETRY_DELAYS_MS array is now readonly [0, 16, 48] (due to as const) — ReadonlyArray.map() is fully supported so there is no type or runtime issue
• THEME_CONSTANTS.RESERVED_PIERRE_TOKEN_COLORS replaces the identical as const object in pierre.ts; the key-lookup type inference in normalizeHighlightedColor is unaffected
• Explicit return types were added to six previously-inferred helper functions in pierre.ts

Confidence Score: 5/5

Safe to merge — purely mechanical constant extraction with no behavior changes

Every replacement is a 1-to-1 substitution of an identical value; TypeScript types are preserved (including as const narrowing and ReadonlyArray.map() compatibility); no P0 or P1 findings

No files require special attention

Important Files Changed

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    C[src/core/constants.ts]

    C -->|DIFF_CONTEXT_LINES| L[src/core/loaders.ts]
    C -->|UI_LAYOUT_CONSTANTS\nWATCH_POLL_INTERVAL_MS| A[src/ui/App.tsx]
    C -->|UI_SCROLL_CONSTANTS| D[src/ui/components/panes/DiffPane.tsx]
    C -->|UI_SCROLL_CONSTANTS| V[src/ui/components/scrollbar/VerticalScrollbar.tsx]
    C -->|DEFAULT_TAB_SIZE\nHIGHLIGHTER_PREFERRED\nTHEME_CONSTANTS\nTOKENIZE_MAX_LINE_LENGTH| P[src/ui/diff/pierre.ts]

_{Reviews (1): Last reviewed commit: "refactor: centralize shared render const..." | Re-trigger Greptile}