Fix terminal chat auto-expand for commands without visible output

[meganrogge]

fix #290480

Shell integration sequences (PromptStart, CommandStart, CommandExecuted, CommandFinished) fire multiple data events even for commands with no visible output. The old threshold of > 1 was too low, causing hasRealOutput to return true for sleep 2 since it receives ~4 SI sequence events. Raising the threshold to > 4 means only commands with actual ongoing output (like progress bars) will trigger the fallback, while silent long-running commands like sleep won't falsely auto-expand.

cc @Tyriar

[Copilot]

Pull request overview

This PR fixes an issue where terminal chat incorrectly auto-expands output for commands with no visible output (like sleep 3). The fix adjusts the threshold for detecting "real" terminal output from more than 1 data event to more than 4 data events.

Changes:

• Increased the data event threshold from > 1 to > 4 to distinguish between shell integration sequences (which fire ~4 events) and actual command output
• Updated comments to clarify that shell integration sequences fire multiple times per command (PromptStart, CommandStart, CommandExecuted, CommandFinished, etc.)

[Copilot]

Consider extracting the magic number 4 into a named constant with documentation. The threshold value is empirically determined based on shell integration sequences firing (PromptStart, CommandStart, CommandExecuted, CommandFinished), but this isn't immediately obvious from the code. A constant like SHELL_INTEGRATION_SEQUENCE_COUNT = 4 with a comment explaining why this specific value was chosen would make the code more maintainable and prevent future changes from inadvertently breaking this logic.