What is credential injection?
Credential injection is the timing property that keeps a secret out of the model. The planner reasons over a token; the executor resolves that token to a value inside the browser session at fill time; and the value is redacted from the returned action path, the live frames and the logs. Nothing between the vault and the input field holds the plaintext.
Why it matters
Where a credential is resolved decides who can see it. Resolving at plan time puts it in a prompt, a trace and a log; resolving at fill time puts it in one keystroke sequence inside an isolated session.