fix(error-tracking): search debug IDs progressively

[jhssilva]

What does this change?

Searches built JavaScript artifacts progressively for their injected ddDebugId instead of stopping after the first 1 KiB.

• Reads in 1 KiB chunks.
• Stops immediately after finding a valid debug ID, so the common case still performs one read.
• Retains a 64-character overlap so an ID split across two reads is matched.
• Keeps memory bounded to the current chunk plus overlap.
• If no debug ID exists, accepts reading the artifact to EOF as the rare worst case.

This is intentionally separate from the bundler-specific fixes:

• PR #487 coordinates esbuild post-build injection with sourcemap upload.
• PR #488 keeps Rollup injection after normal chunk transforms.

Tracking issue: RUM-18038

Validation

• 8/8 focused tests pass.
• Covers the one-read common case, a debug ID after the first chunk, a debug ID split across chunks, an absent debug ID that scans to EOF, and unreadable files.
• Focused lint and Error Tracking typechecking pass.

Exact PR package matrix:

Bundler	IDs extracted before upload	Runtime IDs observed	Result
webpack	4/4	2/2	PASS
Vite	6/6	2/4 loaded IDs	PASS
Rollup	4/4	2/2	PASS
esbuild	0/7	2/5 loaded IDs	Expected failure without PR #487
Rspack	4/4	2/2	PASS

The Rollup result uses PR #489 without PR #488, confirming progressive discovery finds the entry debug ID beyond the initial 1 KiB.

The locally stacked PR #487 + PR #489 esbuild package extracted 7/7 debug IDs and observed both runtime-loaded IDs, confirming compatibility once artifact readiness is present.

All five exact PR packages also passed static production builds, deterministic rebuild checks, and browser entry/lazy registration. Staging RUM search returned zero indexed events for all generated targets during the retry window, despite successful browser intake, so this run could not revalidate downstream deobfuscation.

[Copilot]

Pull request overview

This PR updates the Error Tracking sourcemap pipeline to extract injected ddDebugId values by scanning built JavaScript artifacts progressively (in fixed-size chunks with overlap) instead of only inspecting the initial prefix, improving reliability across bundlers/transforms that may move the injected snippet later in the file.

Changes:

• Replaces prefix-only reads with a progressive 1 KiB chunk scan that stops early on match and retains a small overlap for boundary-split literals.
• Exposes the chunk size constant and adds unit tests covering early stop, later-in-file IDs, split-across-chunks IDs, scan-to-EOF, and unreadable files.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/plugins/error-tracking/src/sourcemaps/debugId.ts	Implements progressive chunked scanning with overlap to find ddDebugId without reading entire bundles in the common case.
packages/plugins/error-tracking/src/sourcemaps/debugId.test.ts	Adds coverage for the progressive read behavior and related edge cases.

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[jhssilva]

/merge

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2026-08-19 15:09:06 UTC ℹ️ Start processing command /merge

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2026-08-19 19:13:17 UTC⚠️MergeQueue: This merge request was unqueued

devflow unqueued this merge request: It did not become mergeable within the expected time

[jhssilva]

/code blockers

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Checking merge blockers for #489...

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2026-08-20 16:26:02 UTC ℹ️ Devflow:/code blockers

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[jhssilva]

/code blockers

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2026-08-20 16:33:04 UTC ℹ️ Devflow:

Checking merge blockers for #489...

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Detected 3 merge blocker(s) to address:

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