Emit env var names in telemetry config

[bm1549]

Summary

• Telemetry config names now use the canonical environment variable name (e.g. DD_TRACE_GENERATE_ROOT_SPAN) instead of the INI-derived dot notation (e.g. trace.generate_root_span)
• Uses cfg->names[0] directly from the memoized config entry, which is the original env var name from the CONFIG() macro definitions
• No performance impact — names[0] is a stack-allocated buffer already in memory

Motivation

The backend automatically opens PRs that map config telemetry based on the config registry. Previously, PHP emitted INI-derived names like trace.generate_root_span which don't match the env var names in the registry, so those auto-generated PRs couldn't map PHP configs correctly. By emitting the standard env var name (e.g. DD_TRACE_GENERATE_ROOT_SPAN), the auto-generated backend PRs can map PHP configs without issues.

Companion PR

• System tests: Update PHP telemetry config name mappings for env var format system-tests#6747

Test plan

• tests/ext/telemetry/config.phpt — verifies telemetry config names are emitted as env var names
• tests/ext/library_config/fleet_config.phpt — verifies fleet stable config telemetry names
• tests/ext/library_config/local_config.phpt — verifies local stable config telemetry names
• tests/ext/appsec/sca_flag_is_sent_*.phpt (5 tests) — verifies SCA config telemetry names
• All tests pass locally in Docker (php-8.3_bookworm-6, debug build)

🤖 Generated with Claude Code

[datadog-prod-us1-4]

⚠️ Tests

✨ Fix all issues with BitsAI or with Cursor

⚠️ Other Violations

🧪 1 Test failed

tests.parametric.test_telemetry.Test_Stable_Configuration_Origin.test_stable_configuration_origin_extended_configs_good_use_case[local_cfg0-library_env0-fleet_cfg0-expected_origins0, parametric-php] from system_tests_suite     (Fix with Cursor)

assert None is not None

self = <tests.parametric.test_telemetry.Test_Stable_Configuration_Origin object at 0x7fd3ac4b4f50>
local_cfg = {'DD_TAGS': 'tag1:value1,tag2:value2', 'DD_TRACE_PROPAGATION_STYLE': 'tracecontext'}
fleet_cfg = {'DD_TRACE_PROPAGATION_STYLE': 'datadog'}
test_agent = <utils.docker_fixtures._test_agent.TestAgentAPI object at 0x7fd3ab538fb0>
test_library = <utils.docker_fixtures._test_clients._test_client_parametric.ParametricTestClientApi object at 0x7fd3ab539280>
expected_origins = {'tags': 'local_stable_config', 'trace_propagation_style': 'fleet_stable_config'}

    @pytest.mark.parametrize(
...

ℹ️ Info

No other issues found (see more)

❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 60.70% (+0.00%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: fca7105 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

[pr-commenter]

Benchmarks [ tracer ]

Benchmark execution time: 2026-04-13 23:47:17

Comparing candidate commit fca7105 in PR branch worktree-brian.marks+telemetry-env-var-names with baseline commit df43587 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 192 metrics, 2 unstable metrics.

[bwoebi]

Looks good to me :-)