Post a harness reply to the visitor
Append an external_agent turn to the conversation spine and deliver it to the visitor (chat push / SMS reply through the same compliance chokepoint as the AI — opt-out, quiet-hours, and consent are enforced identically). Idempotent by client_message_id: a replay returns the original receipt. The first message flips the session claimed→active. Harness messages meter exactly like AI messages. mediaUrls is chat-only (supplying it on an SMS session → 422).
Authorizations
Flowyte secret API key (Authorization: Bearer flowyte_sk_live_…). Scope-gated; is scoped to your organization — a key can never reach another tenant. The listed scopes in each operation's apiKey requirement are the scopes that key must hold. The tokenUrl is nominal: keys are minted in the dashboard.
Path Parameters
The escalation session id whose conversation turns you are reading or replying to.