[BUG] Compilation fails on applyTo patterns with multiple brace groups

[sergio-sisternes-epam]

Describe the bug

apm compile fails with Distributed compilation failed: 'ts,js,mts,mjs' when an instruction uses an applyTo pattern containing multiple brace groups, e.g. **/*.{test,spec}.{ts,js,mts,mjs}.

The root cause is in _expand_glob_pattern() at src/apm_cli/compilation/context_optimizer.py (line ~755). The method:

1. Finds the first brace group {test,spec} via regex
2. Replaces it with {}, producing **/*.{}.{ts,js,mts,mjs}
3. Calls Python's str.format() on the result — which interprets the second brace group {ts,js,mts,mjs} as a format placeholder
4. This raises KeyError: 'ts,js,mts,mjs'

The exception propagates up to compile_distributed() which catches it generically, producing the unhelpful error message.

To Reproduce

1. Create an instruction file with applyTo: "**/*.{test,spec}.{ts,js,mts,mjs}" in its frontmatter
2. Run apm compile --verbose
3. Compilation fails with:

   Compilation failed with 1 errors:
     ❌ Distributed compilation failed: 'ts,js,mts,mjs'
   

Expected behavior

The pattern should be fully expanded into all combinations:

• **/*.test.ts, **/*.test.js, **/*.test.mts, **/*.test.mjs
• **/*.spec.ts, **/*.spec.js, **/*.spec.mts, **/*.spec.mjs

Environment (please complete the following information):

• OS: macOS
• Python Version: 3.13.11
• APM Version: 0.7.4
• VSCode Version: N/A (CLI only)

Logs

⚙️ Starting context compilation...
Compiling for AGENTS.md (VSCode/Copilot) - detected .github/ folder
Verbose mode: showing source attribution and optimizer analysis
⏱️  📊 Project Analysis: 7.7ms
Compilation failed with 1 errors:
  ❌ Distributed compilation failed: 'ts,js,mts,mjs'

Additional context

Single brace group patterns like **/*.{ts,tsx} are widely used across the APM ecosystem — in APM's own templates (hello-world), official docs (examples.md), and tests. The brace expansion logic in _expand_glob_pattern handles single groups correctly but fails on multiple groups. Multi-brace patterns like **/*.{test,spec}.{ts,js,mts,mjs} are standard glob syntax (supported by VS Code's files.include/files.exclude, bash, zsh, etc.) and should be expected in applyTo values.

The fix should recursively expand all brace groups in a pattern, not just the first one. Additionally, str.format() should be avoided since remaining brace groups in the string will be misinterpreted as format placeholders — string concatenation or str.replace() (with maxcount=1) would be safer.