DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
Hook commands now validate that environment variable references (${...}) match the correct variables available for that hook type. Invalid references produce warnings during validation.
Evidence
Hook env var validation (search for "Hook command references ${")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
