fix: Improve usage reporting

[jsonbailey]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

• Implements AIC-1636
• Spec: https://github.com/launchdarkly/sdk-specs/pull/132 and https://github.com/launchdarkly/sdk-specs/pull/135
• JS reference: fix: Improve usage reporting js-core#1108
• Python reference: fix: Improve usage reporting python-server-sdk-ai#92
• .NET reference: fix: Improve usage reporting dotnet-core#228

Describe the solution you've provided

Updates the Go AI SDK's usage tracking to align with the updated spec. Four categories of changes:

1. Renamed usage tracking event keys to the unified $ld:ai:usage:* prefix:

   Old Key	New Key
   $ld:ai:config:function:single	$ld:ai:usage:completion-config
   $ld:ai:judge:function:single	$ld:ai:usage:judge-config

2. Added SDK info tracking on construction ($ld:ai:sdk:info). NewClient now fires a one-time tracking event with aiSdkName, aiSdkVersion, and aiSdkLanguage, using an anonymous context (kind ld_ai, key ld-internal-tracking). SDK metadata constants (SDKName, SDKLanguage) are defined in package_info.go alongside Version.

3. Renamed Config method to CompletionConfig. The old Config method is preserved as a deprecated proxy to CompletionConfig.

4. Changed usage tracking data format from a plain string to an object containing configKey, consistent with the other SDK implementations.

Note: This SDK does not currently have agent config, createChat, or createJudge methods, so only the completion-config and judge-config usage event keys needed updating.

Human review checklist

• Verify event key strings exactly match the spec ($ld:ai:sdk:info, $ld:ai:usage:completion-config, $ld:ai:usage:judge-config)
• Verify the anonymous context (kind ld_ai, key ld-internal-tracking) matches spec requirement 1.2.2.1
• Confirm the SDK name "launchdarkly-go-server-sdk-ai" is correct for this package (now in package_info.go)
• Verify that SDK info tracking firing per Client instantiation (rather than once globally) aligns with spec intent
• Note: the deprecated Config method delegates to CompletionConfig, so it will also emit the $ld:ai:usage:completion-config tracking event — confirm this is desired behavior
• Confirm that exporting SDKName and SDKLanguage as public constants is acceptable for the package API surface

Updates since last revision

Addressed reviewer feedback:

• Alphabetized event key constants
• Removed unnecessary doc comment on NewClient
• Updated CompletionConfig and JudgeConfig doc comments with clearer descriptions
• Moved SDK name and language into package_info.go as exported constants (SDKName, SDKLanguage)

Additional context

• Link to Devin run: https://app.devin.ai/sessions/8eca2a61efec4ceb92a13c9e9d5969b9
• Requested by: @jsonbailey
• All tests pass locally
• CI note: Windows, Go 1.24 failure is a pre-existing flaky test in ldfilewatch (unrelated to these changes); all ldai checks pass
  on all platforms

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Note

Medium Risk
Medium risk because it changes analytics/telemetry semantics (new event keys/payloads and a new constructor-time metric) and introduces a new public API (CompletionConfig) while deprecating Config, which may affect downstream expectations around tracking and call patterns.

Overview
Updates the Go AI SDK’s metric reporting to match the latest spec by renaming usage event keys to the $ld:ai:usage:* namespace and changing the metric data payload from a raw string to an object containing configKey.

NewClient now emits a one-time $ld:ai:sdk:info metric on construction using an anonymous ld_ai context and SDK metadata (SDKName, SDKLanguage, Version).

Renames Client.Config usage to CompletionConfig (with Config kept as a deprecated delegating wrapper) and updates JudgeConfig tracking to the new judge usage event; tests are updated/added to assert the new events and payloads.

^{Written by Cursor Bugbot for commit 5d2ca43. This will update automatically on new commits. Configure here.}

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[devin-ai-integration]

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 4 additional findings.