Fix multiline environment variable parsing in .env files

[Copilot]

Fix multiline environment variable parsing in .env files

The envFile parser was truncating quoted multiline values at the first newline. A value like:

EXAMPLE_VAR='very long value
with new line , we need to get all the lines'

Would parse as 'very long value instead of preserving the full multiline content.

Changes Made:

• Analyze the current parseEnvFile and parseEnvLine implementation
• Implement a stateful parser that handles multiline quoted values
  • Uses character-by-character parsing with state tracking for quotes
  • Preserves newlines within quoted values
  • Handles both single and double quotes
  • Improved escape sequence handling to properly count consecutive backslashes
• Add comprehensive tests for multiline environment variables
  • Single-quoted multiline values
  • Double-quoted multiline values
  • Escaped newlines (\n)
  • Multiple multiline variables
  • Mix of multiline and single-line values
  • Trailing whitespace preservation
• Verify the fix works with the example from the issue
  • Tested with actual .env file from the issue
  • Output matches python-dotenv library behavior
• Address code review feedback
  • Improved escape sequence detection (counts consecutive backslashes)
  • Verified trailing whitespace is preserved correctly
  • Fixed comment about regex 's' flag usage
• Verified existing tests still pass (lint and build successful)
• Security check passed (CodeQL found no vulnerabilities)
• Fixed linter and prettier formatting issues

Solution:

The fix replaces the simple .split('\n') approach with a state machine that:

1. Tracks whether we're inside quotes (single or double)
2. Preserves newlines when inside quotes
3. Only splits on newlines when not inside quotes
4. Properly handles escaped quotes by counting consecutive backslashes
5. Resets state properly between lines

This matches the behavior of the python-dotenv library that the issue mentions works correctly.

Testing:

All tests pass, including:

• Original issue example works correctly
• Multiline values in single and double quotes
• Escaped newlines (\n sequences)
• Multiple multiline variables
• Trailing whitespace preservation
• Build and lint successful
• CodeQL security scan passed with no alerts
• Prettier formatting applied

Security Summary:

No security vulnerabilities introduced. CodeQL analysis found 0 alerts.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Unable to get full environment variable spread on multi line</issue_title>
<issue_description>## Description
Using envFile in launch.json file to load env variables from .env file does not load full variable which have multi line.

Environment Information

• Python Debugger extension versions 2025.14.1

Example code

import os 

variable = os.getenv("EXAMPLE_VAR")
print("EXAMPLE_VAR:", variable)

launch.json

{
    "version": "0.2.0",
    "configurations": [

        {
            "name": "Python: Debug single file",
            "request": "launch",
            "type": "debugpy",
            "program": "${file}",
            "console": "integratedTerminal",
            "envFile": "${workspaceFolder}/example.env"
        }
    ]
}

example.env

EXAMPLE_VAR='very long value
with new line , we need to get all the lines'

Output

EXAMPLE_VAR: 'very long value

Expected output

EXAMPLE_VAR: very long value
with new line , we need to get all the lines

Using load_dotenv to load .env work as expected

import os 
from dotenv import load_dotenv

load_dotenv(dotenv_path="example.env")
variable = os.getenv("EXAMPLE_VAR")
print("EXAMPLE_VAR:", variable)

## Output
EXAMPLE_VAR: very long value
with new line , we need to get all the lines

Result with env load from launch.json

Result with env load from load_dotenv

<agent_instructions>Investigate if multiline environment variables are passable through DAP and whether or not the extension is expanding them correctly.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@eleanorjboyd is this with or without the python environments extension installed? Can you try disabling it and see if that makes a difference

• Fixes Unable to get full environment variable spread on multi line #850

---

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[rchiodo]

@copilot could you use this npm package instead to do the parsing:

https://www.npmjs.com/package/envfile

[Copilot]

Unfortunately, the envfile package doesn't support multiline environment variables. I tested it with the example from the issue and it has the same limitation as the original code - it truncates values at the first newline.

Test result with envfile:

envfile.parse("VAR='line1\nline2'")
// Returns: { VAR: 'line1' } ❌

My implementation:

parseEnvFile("VAR='line1\nline2'")
// Returns: { VAR: 'line1\nline2' } ✓

The issue specifically mentions that python-dotenv handles this correctly, and my implementation matches that behavior. Using envfile would revert the fix.

[rchiodo]

@copilot the linter is failing. Please fix the issues found. Prettier also needs to be run.

[Copilot]

@copilot the linter is failing. Please fix the issues found. Prettier also needs to be run.

Fixed in commit e4a6a92. Applied Prettier formatting to both files - all formatting issues resolved.