Audita API key credentials are now optional

architecture.md

@@ -132,7 +132,7 @@ Audita config keys:
 
 - `pipeline.audita.binary` (required)
 - `pipeline.audita.timeout` (default: `3h`)
-- `pipeline.audita.llm_api_key_env` (required; default: `AUDITA_LLM_API_KEY`)
+- `pipeline.audita.llm_api_key_env` (optional; default: `AUDITA_LLM_API_KEY`)
 - `pipeline.audita.modules` (default sequence: `glossary,homophones,glossary,spoken_word,grammar,homophones,glossary`)
 - `pipeline.audita.base_url` (default: `https://openrouter.ai/api/v1`)
 - `pipeline.audita.model` (default: `openrouter/google/gemma-4-31b-it`)
@@ -145,6 +145,7 @@ Audita secret-handling policy:
 
 - `llm_api_key_env` stores only the environment variable **name**.
 - API key values are read from the process environment at runtime and are not stored in `pipeline.yml`, manifest metadata, generated configs, or logs.
+- If the named env var is missing/empty, the Audita adapter omits `AUDITA_LLM_API_KEY` from subprocess env overrides and continues.
 
 Validation currently enforces:
 
@@ -160,7 +161,6 @@ Validation currently enforces:
 - optional `pipeline.seriatim.env.*` values must be `> 0` when provided.
 - `pipeline.audita.binary` is required.
 - `pipeline.audita.timeout` must parse as Go duration.
-- `pipeline.audita.llm_api_key_env` is required.
 - `pipeline.audita.modules` must be non-empty and each entry must be one of `glossary|homophones|spoken_word|grammar`.
 - `pipeline.audita.base_url` must be a valid URL when provided.
 - `pipeline.audita.model` is required.