The bounce model requires that a worker never touch UI-thread-owned
state: it should capture what it needs on the UI thread and pass that
in. Guard the two central accessors -- Model() (the git model) and
Context() (the context manager, which owns the mutable
current-context/stack) -- with a debug-only panic when they're called
off the UI thread. Since the integration tests run with -debug, a stray
worker access now fails deterministically and points at itself, rather
than surfacing later as a probabilistic data race.
One supporting change make the assertion usable: the integration test
driver inspects gui state from the test goroutine, so
GuiDriver.CurrentContext reads the context manager directly rather than
through the now-guarded c.Context().
Contexts() (the registry of context objects) is deliberately left
unguarded: workers legitimately fetch a context to grab its mutex or
check identity, so a blanket assertion there would flag safe accesses.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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