fix: prevent terminal history duplication on restart

[sgeraldes]

Problem

Terminal output was being duplicated when restarting Wave Terminal, causing the same content to appear multiple times in the scrollback buffer.

Root Cause

When Wave Terminal restarts and loads a terminal block:

1. Cache restoration: Loads the serialized terminal state (full scrollback buffer + screen) that was saved at PTY offset X
2. Main file append: Then loads the raw PTY data from offset X onward and re-renders it

The issue is that the serialized cache already contains the rendered terminal output from offset 0 to X. When the raw PTY data from offset X is then appended and re-rendered, it creates duplicates because that data was already processed into the cached terminal state.

Solution

Modified loadInitialTerminalData() in frontend/app/view/term/termwrap.ts to:

• Track whether we loaded from cache with loadedFromCache flag
• When cache is loaded, fetch the main terminal file from ptyOffset (which returns only NEW data that arrived after the cache was saved)
• Only append truly new data that wasn't part of the cached state

Testing

1. Run some commands in a terminal
2. Wait for state to be saved (5 second idle timeout)
3. Restart Wave Terminal
4. Verify terminal history appears correctly without duplication

Changes

• Modified frontend/app/view/term/termwrap.ts (lines 716-757)
• Added better logging to track cache usage and offsets

Fixes the terminal history corruption issue where scrolling up would show repeated blocks of output.

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[coderabbitai[bot]]

Walkthrough

This pull request modifies termwrap.ts to enhance terminal state management. In handleOsc7Command, logic is added to automatically update the active tab's base directory when it is unlocked and either unset or set to "~". In loadInitialTerminalData, a loadedFromCache flag tracks whether data originates from cache, which determines whether the main data fetch uses ptyOffset or offset 0. Additionally, the terminal write operation is conditional: mainData is only appended if both mainFile and mainData exist and mainData has non-zero byteLength, preventing unnecessary writes.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix: prevent terminal history duplication on restart' directly summarizes the main change—fixing a bug that caused terminal output duplication when Wave Terminal restarts, which is the core issue addressed in the changeset.
Description check	✅ Passed	The description clearly explains the problem (terminal duplication on restart), root cause (cache + raw data re-rendering), solution (loadedFromCache flag and offset handling), and testing steps, all directly related to the changeset.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing touches

• [ ] 📝 Generate docstrings

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