Add safe Live Debugger file extension filtering

[watson]

What and why?

A broad liveDebugger.include glob can currently select CSS and other files that should not be instrumented. Add an independent file-extension guard so path selection remains flexible without becoming a parsing footgun.

Tracks DEBUG-6161.

How?

• Add a case-insensitive fileExtensions option with standard JavaScript and TypeScript defaults and an explicit all escape hatch.
• Normalize and deduplicate configured extensions and reject empty or malformed arrays.
• Use consistent glob matching for native and child-compilation filtering.
• Document the behavior and cover default, custom, glob, query-suffixed, and validation cases.

Verification

• yarn test:unit packages/plugins/live-debugger
• yarn workspace @dd/live-debugger-plugin typecheck
• yarn cli integrity

[datadog-prod-us1-5]

✅ All CI checks and tests passed.

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
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[github-actions]

Live Debugger Runtime Benchmark

SDK-loaded dormant-probe runtime overhead, measured against an uninstrumented bundle in the same browser session.

Browser Debugger SDK: 7.12.0 · built 2026-09-03 · S3 ETag 59df9831

Browser	Workload	Quality	Per-call overhead upper
chrome	Hot	clean	<= 2.55 ns
chrome	Tiny	clean	<= 0.04 ns
firefox	Hot	clean	<= 9.54 ns
firefox	Tiny	clean	<= 0.01 ns
safari	Hot	clean	<= 5.69 ns
safari	Tiny	clean	<= 1.05 ns

Full diagnostics

browser  workload  quality  per-call overhead upper  overhead upper         95% CI        A/A diag       block CI  acf(1)   baseline  instrumented                         samples
-------  --------  -------  -----------------------  --------------  -------------  --------------  -------------  ------  ---------  ------------  ------------------------------
chrome   Hot       clean                 <= 2.55 ns        <= 5.14%  2.52..2.55 ns  -0.01..0.01 ns  2.53..2.55 ns    0.07  52.635 ms     55.310 ms   102 (trim 20%, outliers 8.8%)
chrome   Tiny      clean                 <= 0.04 ns        <= 0.53%  0.01..0.04 ns  -0.01..0.01 ns  0.01..0.04 ns    0.15  59.760 ms     59.965 ms  102 (trim 20%, outliers 14.7%)
firefox  Hot       clean                 <= 9.54 ns       <= 38.00%  9.52..9.54 ns  -0.00..0.01 ns  9.52..9.54 ns    0.11  39.840 ms     54.980 ms   102 (trim 20%, outliers 5.9%)
firefox  Tiny      clean                 <= 0.01 ns        <= 0.06%  0.00..0.01 ns  -0.00..0.00 ns  0.00..0.01 ns   -0.10  50.340 ms     50.360 ms   102 (trim 20%, outliers 8.8%)
safari   Hot       clean                 <= 5.69 ns       <= 22.65%  5.68..5.69 ns  -0.01..0.00 ns  5.68..5.69 ns   -0.00  45.140 ms     55.360 ms   102 (trim 20%, outliers 4.9%)
safari   Tiny      clean                 <= 1.05 ns       <= 28.22%  1.05..1.05 ns  -0.00..0.00 ns  1.05..1.05 ns   -0.02  41.100 ms     52.660 ms   102 (trim 20%, outliers 5.9%)

Raw samples are in the live-debugger-runtime-bench-results artifact.