fix: scope column packing to frames with a missing source map

[szegedi]

What

columnNumbers: 'pack' (added in #377) packed the column into the line for every frame. This narrows it to only pack frames whose source map was declared but missing locally (loc.missingMapFile).

Why

That's exactly the set of frames that sets dd:has-missing-map-files and get sent for server-side unminification. Packing every frame instead leaked the packed line into profiles that skip server-side unminification (Node.js profiles whose maps resolved locally, or that never had missing maps) — which would force the deobfuscation backend to strip the packed value back out of every parse-time structure (stacktraces, sample values, indexed samples). That backend cleanup was ballooning (see DataDog/profiling-backend#8762) and it is simpler to solve it here.

With this scoping:

• Packed ⟺ bound for server-side unminification → those frames get resolved to source names by the backend (or, if unresolved, behave exactly like the pre-existing Chrome non-success case).
• Locally-resolved / no-missing-map frames keep their plain line → profiles that skip unminification never carry packed line numbers, so the backend needs no stripping.

This mirrors how the Chrome path already works (Chrome packs column << 32 | line into the internal frame at parse time and is always unminified), and it lets the backend-side stripping work (profiling-backend#8762) be dropped.

Changes

• ts/src/profile-serializer.ts — getLine packs only when columnNumbers === 'pack' && loc.missingMapFile.
• ts/test/test-profile-serializer.ts — updated the 'pack' tests: without a missing map, 'pack' no longer packs (time + heap); added tests that a missing-map frame is packed under 'pack' and left plain under the default 'drop'.

Testing

test-profile-serializer / test-profile-encoder / test-sourcemapper — 55 passing. eslint clean.

Follow-ups

• dd-trace-js: opt into columnNumbers: 'pack' on the wall profiler.
• With this change, profiling-backend#8762 (backend stripping) should no longer be needed — will confirm and close it out.

Jira: PROF-15467

[github-actions]

Overall package size

Self size: 2.45 MB
Deduped: 3.15 MB
No deduping: 3.15 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | pprof-format | 2.2.3 | 500.55 kB | 500.55 kB | | source-map | 0.8.0 | 185.66 kB | 185.66 kB | | node-gyp-build | 4.8.4 | 13.86 kB | 13.86 kB |

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

[szegedi]

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