fix: stderr tokens are no longer injected when in development mode

[cacieprins]

• Closes webpack info logs less readable with CYPRESS.STDERR annotations #32569

Additional details

Most notably in CT, when running Cypress in development mode, the STDERR marking tokens were appearing in the final cli output. This:

• Ensures that we are not adding tokens when we shouldn't (e.g., debugging electron, internal development mode for Cypress)
• Ensures that we are not stripping tokens when we aren't adding them
• Refactors to make this distinction easier to determine

Steps to test

Check out and build; run cypress:run --component --project ./packages/driver, ensure no tokens exist in the output

How has the user experience changed?

PR Tasks

• Have tests been added/updated?
• [NA] Has a PR for user-facing changes been opened in cypress-documentation?
• [NA] Have API changes been updated in the type definitions?

---

Note

Disable stderr tag injection in development or with ELECTRON_ENABLE_LOGGING=1, refactor filtering/TagStream to use tagsDisabled(), update tests, and add changelog entry.

• stderr filtering:
  • Tagging control: Introduce tagsDisabled() to disable tags when CYPRESS_INTERNAL_ENV=development or ELECTRON_ENABLE_LOGGING=1.
  • Refactor Filter: Remove disableTags param; decide tagging via tagsDisabled() and only create FilterTaggedContent when enabled.
  • Refactor TagStream: Add conditional tag() method, output Buffer.from('') for empty chunks, and add verbose debug namespace.
  • logError: Use tagsDisabled() to bypass tags; minor comment cleanup.
  • Tests: Update/spec new cases to cover tag disabling, buffering behavior, and environment stubbing; use vi.stubEnv/vi.unstubAllEnvs.
• Changelog:
  • Add 15.4.1 bugfix note describing reduced verbose stderr tagging in development/Electron logging modes.

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[cypress]

cypress    Run #66316

Run Properties:   Failed #66316  •  5af007d18a: Merge branch 'develop' into fix/stderr-tokens-dev-mode

Project	cypress
Branch Review	fix/stderr-tokens-dev-mode
Run status	Failed #66316
Run duration	21m 03s
Commit	5af007d18a: Merge branch 'develop' into fix/stderr-tokens-dev-mode
Committer	Cacie Prins
View all properties for this run ↗︎

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Test results
Failures	1
Flaky	15
Pending	1102
Skipped	4
Passing	26706
View all changes introduced in this branch ↗︎

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Warning

Partial Report: The results for the Application Quality reports may be incomplete.

UI Coverage  45.27%
Untested elements	186
Tested elements	158

Accessibility  97.97%
Failed rules	4 critical   8 serious   2 moderate   2 minor
Failed elements	101

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Tests for review

  cypress/e2e/studio/studio.cy.ts • 1 failed test • app-e2e

View Output

Test		Artifacts
Cypress Studio > updates an existing test with assertions		Test Replay Screenshots

  commands/files.cy.js • 1 flaky test • 5x-driver-electron

View Output

Test		Artifacts
... > throws when there is an error reading the file		Test Replay

  issues/28527.cy.ts • 1 flaky test • 5x-driver-electron

View Output

Test		Artifacts
issue 28527 > fails and then retries and verifies about:blank is not displayed		Test Replay Screenshots

  e2e/origin/config_env.cy.ts • 1 flaky test • 5x-driver-inject-document-domain-chrome

View Output

Test		Artifacts
cy.origin- Cypress.config() > serializable > overwrites different values in secondary if one exists in the primary		Test Replay

  e2e/origin/config_env.cy.ts • 1 flaky test • 5x-driver-inject-document-domain-chrome:beta

View Output

Test		Artifacts
cy.origin- Cypress.config() > serializable > overwrites different values in secondary if one exists in the primary		Test Replay

  e2e/origin/config_env.cy.ts • 1 flaky test • 5x-driver-chrome

View Output

Test		Artifacts
cy.origin- Cypress.config() > serializable > overwrites different values in secondary if one exists in the primary		Test Replay

The first 5 flaky specs are shown, see all 13 specs in Cypress Cloud.