fix(error-tracking): wait for debug ID injection before sourcemap upload

[jhssilva]

What

Add an explicit artifacts-ready barrier so Error Tracking waits until esbuild finishes rewriting JavaScript and source-map artifacts before discovering sourcemaps and extracting debug IDs.

The early esbuild build-report callback queues the gated upload instead of blocking the later injection callback. Concurrent lifecycle attempts share one upload promise.

Why

RUM-18038 live testing showed esbuild uploaded all sourcemaps but extracted debug IDs for 0/N because upload ran before debug-ID injection completed.

How it works

1. The RUM plugin generates a deterministic debug ID and requests its injection into each JavaScript chunk.
2. The injection plugin writes the debug-ID snippet into the bundle and regenerates the sourcemap so generated locations still map to the correct original source.
3. Error Tracking waits until every rewritten .js and .map artifact is ready.
4. The uploader reads the final JavaScript, extracts the already-injected ddDebugId, and uploads that value with the final JavaScript and sourcemap.

The uploader does not inject or modify the bundle. The synchronization prevents it from reading or uploading artifacts while esbuild is still rewriting them.

Tests

• 383 focused unit/integration tests passed
• Core, factory, injection, and Error Tracking typechecks passed
• ESLint passed
• Regression test verifies every split esbuild JavaScript output has an extractable debug ID when upload starts
• Existing injection E2E coverage verifies that adding a banner preserves the original source location through the regenerated sourcemap

Jira: https://datadoghq.atlassian.net/browse/RUM-18038

[buranmert]

relevant comment from the previous PR: #470 (comment)

[Copilot]

Pull request overview

Friend, this PR synchronizes esbuild artifact rewriting with Error Tracking sourcemap uploads.

Changes:

• Adds an artifact-readiness barrier to shared context.
• Delays and deduplicates sourcemap uploads until injection finishes.
• Adds barrier and debug-ID regression coverage.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/core/src/types.ts	Defines artifact barrier APIs.
packages/factory/src/helpers/context.ts	Implements barrier lifecycle.
packages/factory/src/helpers/context.test.ts	Tests resolution, rejection, and reuse.
packages/plugins/injection/src/index.ts	Marks esbuild artifacts pending.
packages/plugins/injection/src/esbuild.ts	Resolves the barrier after rewriting.
packages/plugins/error-tracking/src/index.ts	Gates and deduplicates uploads.
packages/plugins/error-tracking/src/index.test.ts	Adds synchronization and debug-ID tests.
packages/tests/src/_jest/helpers/mocks.ts	Extends context mocks.

Suppressed comments (1)

packages/plugins/error-tracking/src/index.test.ts:111

• Split the mapped promise and the push into named steps. The current nested calls violate the repository’s call-argument convention and make this assertion setup harder to follow.

            debugIdsAtUpload.push(
                ...(await Promise.all(
                    javascriptOutputs.map(({ filepath }) => extractDebugId(filepath)),
                )),
            );

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[buranmert]

that's a bit beyond my understanding of JS build plugins for me to propose a better way to achieve that.
i'm fine as long as our end-to-end tests pass 👍