fix: Screen isolation output not captured for quoted commands

[konard]

Summary

This PR fixes issue #25 where commands with quoted strings (e.g., echo "hello") would not show their output when using screen isolation in attached mode.

Problem

When running:

$ --isolated screen --verbose -- echo "hello"

The output would only show [screen is terminating] without the expected "hello" output, even though the command executed successfully with exit code 0.

Root Cause

The code used execSync with a constructed shell command string where each argument was wrapped in double quotes. When the command itself contained double quotes, this caused shell parsing errors due to nested quoting:

// Broken approach:
execSync(`screen ${screenArgs.map((a) => `"${a}"`).join(' ')}`, { ... });

// For echo "hello" this became:
// screen "-dmS" "session" "/bin/sh" "-c" "(echo "hello") 2>&1 | tee "...log""
// The nested quotes break shell parsing!

Solution

Use spawnSync with an array of arguments instead of execSync with a string. Node.js/Bun's spawnSync handles argument quoting correctly by passing arguments directly to the process without shell interpretation.

// Fixed approach:
const result = spawnSync('screen', screenArgs, { stdio: 'inherit' });

Changes

• src/lib/isolation.js: Replace execSync with spawnSync for screen commands
• test/isolation.test.js: Add 2 regression tests for quoted string commands
• docs/case-studies/issue-25/: Add case study documentation with root cause analysis
• experiments/: Add debug experiments used during investigation
• package.json: Bump version to 0.7.3

Test Results

All 25 isolation tests pass, including the 2 new regression tests:

✓ should capture output from commands with quoted strings (issue #25)
✓ should capture output from commands with complex quoted strings

Fixes #25

🤖 Generated with Claude Code

[konard]

🤖 Solution Draft Log

This log file contains the complete execution trace of the AI solution draft process.

💰 Cost estimation:

• Public pricing estimate: $7.380758 USD
• Calculated by Anthropic: $5.012937 USD
• Difference: $-2.367821 (-32.08%)
  📎 Log file uploaded as GitHub Gist (814KB)
  🔗 View complete solution draft log

---

Now working session is ended, feel free to review and add any feedback on the solution draft.