#618: icons::USE_NERD_FONTS is unguarded process-global render state — one future test away from nondeterministic snapshot failures - #644
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JDonaghy merged 1 commit intoAug 9, 2026
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…-global Icon::s()/c() read a process-wide AtomicBool to pick between the nerd glyph and ASCII fallback, and it's written from several production paths (tui_main, shell_app, settings :set nerdfonts, gtk). Since Rust's test harness runs tests concurrently across threads in one process, a single future test flipping this flag would nondeterministically corrupt every snapshot test running on another thread at the same time -- exactly the failure shape #615 turned out not to be, but which the #615 audit surfaced as a live landmine. Swap the AtomicBool for a thread_local Cell<bool>. Both backends only ever set-then-render on their own single thread, so this is behavior- preserving in production, while making cross-test corruption structurally impossible: a test that flips the flag can only affect other tests dispatched to the very same worker thread, never concurrently-running tests on other threads. Add regression tests proving the default-true behavior survives the swap and that setting the flag on one thread is invisible to a concurrently-running thread. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Closes #618
Automated PR opened by coordinator for review of issue #618.