[johnmatthewtennant]

Summary

The Buzz Berd Call plugin is adding per-service OpenAI endpoint settings (URL plus its own key for realtime, speech to text and text to speech). berd-call read only OPENAI_API_KEY for all three, so a per-service key could not be passed.

Each service now reads its own variable and falls back to OPENAI_API_KEY when it is unset or blank, so existing setups are unchanged:

Service	Flag	Variable
Realtime and Expert-Spokesperson	--realtime-url	OPENAI_REALTIME_API_KEY
Speech to text	--stt-url	OPENAI_STT_API_KEY
Text to speech	--tts-url	OPENAI_TTS_API_KEY

• One helper, berd_call::openai::openai_key(kind_var), replaces the four inline OPENAI_API_KEY reads. openai_key_var reports which variable supplied the key.
• Missing-key errors, the public TTS and STT startup errors, and the STT benchmark credential_source name the variable that applies. Missing-key messages still contain OPENAI_API_KEY is required.
• The README documents the new variables.

Related issue

N/A. none found.

Testing

Unit tests in openai.rs cover a service key winning over OPENAI_API_KEY, fallback when the service key is unset, and fallback when it is blank. Before the change the winning-key test fails (left: Some(("OPENAI_API_KEY", "shared")), right: Some(("OPENAI_TTS_API_KEY", "tts"))); after it, it passes.

End to end, berd-call synthesize --tts-backend openai ... --allow-paid-openai against a local server that logs the Authorization header (OPENAI_BASE_URL pointed at it):

Environment	Header the server saw
OPENAI_API_KEY=shared-key	Bearer shared-key
OPENAI_API_KEY=shared-key OPENAI_TTS_API_KEY=tts-key	Bearer tts-key
OPENAI_API_KEY=shared-key OPENAI_TTS_API_KEY= (blank)	Bearer shared-key
neither	OPENAI_TTS_API_KEY or OPENAI_API_KEY is required

The realtime and STT paths share the same helper and are covered by the unit tests, not by a live connection. No UI change.

🤖 Generated with Claude Code

[johnmatthewtennant]

🤖 Folded into #416 for review and merge.