responses api behind use-responses-api flag (env-22..24, d-021) — tools + reasoning combinable, stateless with encrypted reasoning, multi-round tool loop

specs/SPEC-001-responder-envelope.md

@@ -152,3 +152,32 @@ Every chat call carries `response_format` = strict JSON schema named
 IMG-02), `picture_edit`, `hack` — all required,
 `additionalProperties: false`, nullable where the protocol allows
 null. Tool-followup calls carry the same format.
+
+### ENV-22 — Responses API path behind a flag (coverage: test)
+
+With `use-responses-api = true`, responder chat calls go to
+`/v1/responses` instead of chat/completions: same model selection
+(default / vision / factual / retry), the same strict envelope schema
+(as `text.format`), tools in the flat Responses shape, and
+`reasoning` = config `reasoning-effort` — tools + reasoning are
+allowed here (the chat/completions 400 from ENV-21 does not apply).
+Flag off (default) = the ENV-21 path, byte-identical behavior.
+Classifier, consolidation and task-proposal calls stay on
+chat/completions.
+
+### ENV-23 — Responses tool loop is stateless and keeps reasoning (coverage: test)
+
+The Responses path runs with `store=false` and
+`include=["reasoning.encrypted_content"]` (nothing retained
+server-side). On a function call, ALL output items — including
+reasoning items — are passed back as input together with one
+`function_call_output` per call (matched by `call_id`, result
+sanitized per SAF-03), so the model continues one chain of thought
+across tool rounds. Up to `responses-tool-rounds` (default 4) rounds
+may call tools; an exhausted loop forces a final tool-less answer.
+
+### ENV-24 — Responses refusals are failed attempts (coverage: test)
+
+A refusal content part in the Responses output yields no answer
+(backoff + retry per ENV-12/ENV-18), exactly like the
+chat/completions path.