gpt-image-2 multi-image + fix: tools need reasoning_effort none on gpt-5.6 (ggg mute bug)

specs/SPEC-001-responder-envelope.md

@@ -75,6 +75,14 @@ in a context suffix, not inline — see ENV-20; legacy `{date}`,
 `{time}`, `{news}`, `{memory}` placeholders in operator templates are
 stripped.
 
+### ENV-21 — Tool calls disable reasoning effort (coverage: test)
+
+When function tools are attached to a chat call, the call carries
+`reasoning_effort` (config `reasoning-effort`, default `"none"`) —
+gpt-5.6 models reject tools + reasoning on chat/completions with a
+400 otherwise (found live on ggg 2026-07-13: IGDB tools made Luma
+mute after the Luna cutover). Tool-less calls stay untouched.
+
 ### ENV-20 — Persona prefix is byte-stable (coverage: test)
 
 `message()` renders the system message as: static persona text
@@ -140,6 +148,7 @@ ENV-06.
 
 Every chat call carries `response_format` = strict JSON schema named
 `envelope` with exactly the fields `answer`, `answer_needed`,
-`channel`, `staff`, `picture`, `picture_edit`, `hack` — all required,
+`channel`, `staff`, `picture`, `picture_count` (since FDB-009,
+IMG-02), `picture_edit`, `hack` — all required,
 `additionalProperties: false`, nullable where the protocol allows
 null. Tool-followup calls carry the same format.