Terminal output capture is unreliable due to race conditions and fixed timeouts

[midhunann]

Location

src/environment.ts (approx. lines 87–96)

---

Problem

The environment detection logic captures terminal output by writing to a temporary file and reading it after a fixed delay. This approach is unreliable and can fail on slower systems or under load.

Current behavior

terminal.sendText(`${checkCommand} ghci > /tmp/ghci_path 2>/dev/null || echo "not found" > /tmp/ghci_path`);

setTimeout(async () => {
    const content = await vscode.workspace.fs.readFile(
        vscode.Uri.file('/tmp/ghci_path')
    );
}, 500);

---

Issues Identified

Race condition

• The file may be read before the terminal finishes writing to it
• Results in false negatives even when tools are installed

Fixed timeout

• Hard-coded 500ms delay is unreliable
• Slower machines or busy systems may require more time

Missing error handling

• No clear handling if the file does not exist
• Errors are silently ignored, making debugging difficult

Fragile design

• Depends on terminal behavior and filesystem timing
• Not suitable for reliable environment detection in a VS Code extension

---

Expected Behavior

• Tool detection should be deterministic and reliable
• No dependency on arbitrary timeouts
• Proper error handling if a tool is missing
• Works consistently across different system speeds and platforms

---

How to Test

1. Install the extension from the VS Code marketplace (or via VSIX).

2. Clone this repository, which contains simple Haskell files for testing:

   https://github.com/midhunann/haskell-test
   

3. Open the repository in VS Code.

4. Run the extension’s Haskell execution commands.

5. Verify that:

   • Environment detection is consistent
   • No false “tool not found” errors occur
   • Behavior is stable on slower systems as well

---

Priority

High — causes intermittent failures and makes environment detection unreliable, especially on slower or heavily loaded systems.

NOTE: Come up with a solution and then start working on this.

[Parthivsurya]

/assign

[Devpool-soc]

Alright @Parthivsurya! Consider yourself officially assigned as now. If you are thinking, "Whoa, hold up, I didn't sign up for this," no worries, just yell "/unassign" and we can pretend this never happened. But if you are sticking around, just know your clock for this ticks out on: 2026-01-14. Don't screw it up :)