[mertefesensoy]

Description

Preserves names such as RequestCount in collected and OTLP-encoded metrics. On main, the same input becomes requestcount for all seven instrument kinds; the local before/after probe verifies the original spelling after this change.

Fixes #3207, following the agreed direction to stop lowercasing names.

Registration still treats names case-insensitively and returns the first spelling. View selection and conflict detection compare names case-insensitively too. Registering another spelling emits the warning required by the SDK name-conflict rule.

Existing queries that depend on lowercase metric names may need updating. The changelog filename is a placeholder for now until this draft PR receives its number.

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected), as anticipated in Metric naming conventions reasoning #3207

Validation

Codex ran the new tests on unchanged main: 22 failed, 5 passed.

I ran these on Windows (Python 3.13.14) with this change:

tox -e py313-test-opentelemetry-sdk   959 passed, 20 skipped, 155 subtests
tox -e precommit                      all hooks passed
tox -e typecheck                      4 os.register_at_fork errors, same on main (Windows-only)
pyright --pythonplatform Linux        0 errors
tox -e lint-opentelemetry-sdk         6 findings in unchanged files (os.fork, one .pyi CRLF)

Checklist:

• I am a human and not a bot
• I have run tox -e precommit
• I have run tox -e typecheck
• I have run the relevant tests and linting tox environments
• This requires the following PR in contrib:

AI-assisted with Codex. Validation commands and results are recorded above.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: mertefesensoy / name: MERT EFE ŞENSOY (99b0e07)

[opentelemetry-pr-dashboard]

Pull request dashboard status

Waiting on reviewers · refreshed 2026-11-05 06:32 UTC

Review the latest changes.

Status above doesn't look right?

• Just replied or pushed? Anything around or after the refresh time above may not be picked up yet — give it a few minutes.
• Anything look wrong? Report it with what you expected; it helps us improve the dashboard.

[knowprasad]

Took a detailed look through the changes in _internal/init.py\ and the test suite.

Preserving the original casing across all seven instrument constructors directly resolves the long-standing behavior from #3207 where names like \RequestCount\ were forced to lowercase. Adding _log_instrument_name_conflict\ provides the exact warning recommended by the SDK specification when another spelling attempts to register against an existing instrument.

Keeping view matching case-insensitive in _view_instrument_match.py\ while preserving the casing chosen in the view definition is a clean approach. It ensures existing view configurations won't silently stop matching previously declared instruments.

The tests in \ est_meter.py\ and \ est_view.py\ cover the casing preservation, conflict warnings, and case-insensitive view lookups thoroughly. Nice work putting this together!