fix: tui launch latency by disabling osc probe #4913
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Firstly, this palette should only be queried on terminals which are not 24-bit capable, which iTerm is, so as written this PR just disables all palette querying.
As such, this will break the user message background color in Terminal.app, which doesn't support true color. On terminals which support 256-color but not 24-bit color, we need to know the color palette of the terminal in order to choose a background color from the indexed palette that is close to the default background color.
FWIW on my machine (admittedly a fancy macbook pro), querying all 256 colors on Terminal.app is somewhere around a few 100 ms. Pretty fast.
There are some other things we could do to hide or reduce this query time:
- We could query a subset of the entire 256 color palette, which on Terminal.app on my machine looks like this:
we could e.g. only query the 24 grayscale colors near the end of the palette, as they're the most likely to be close to the default background color, instead of all 256 colors. perhaps if we detect a default background color that isn't close to white or black, we can query the whole set. - given the 24 grayscale colors are ordered, we could binary search them to find the closest one to the target bg color, for an average of log₂(24) ~= 5 queries.
- we could skip the query altogether and make assumptions about what the palette is. it's probably almost always pretty close to this
| // Many modern GPU terminals ignore OSC, so only perform the query on | ||
| // terminals known to support it. | ||
| if !codex_core::terminal::user_agent().starts_with("iTerm.app") { | ||
| return Ok(None); | ||
| } |
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"ignore OSC" doesn't make sense; there are a large number of OSC codes and different terminals respond to different subsets of them.
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#4957 is my take on this. |
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