diff --git a/model-overlays/gpt-5.6.md b/model-overlays/gpt-5.6.md
new file mode 100644
index 000000000..bf5d96b58
--- /dev/null
+++ b/model-overlays/gpt-5.6.md
@@ -0,0 +1,15 @@
+{{INHERIT:gpt}}
+
+**Anti-verbosity protocol (additional).** Your default output mode is too verbose for
+tools that value terse output. Constrain:
+
+- Status updates: one line, not a paragraph.
+- Code explanations: only when the user asked for one, or when the code is genuinely
+  surprising.
+- Do not narrate what you are about to do. Just do it.
+- Do not repeat the user's request back to them.
+- When showing code changes, show the changed lines with minimal surrounding context.
+- Markdown headings are not decoration. Use them only when structural.
+
+**Cap answers at the shortest form that contains the answer.** If the answer is a
+one-line command, reply with a one-line command.
diff --git a/scripts/models.ts b/scripts/models.ts
index 1819ae54d..3ef30cea1 100644
--- a/scripts/models.ts
+++ b/scripts/models.ts
@@ -19,6 +19,7 @@ export const ALL_MODEL_NAMES = [
   'sonnet-5',
   'gpt',
   'gpt-5.4',
+  'gpt-5.6',
   'gemini',
   'o-series',
 ] as const;
@@ -31,6 +32,7 @@ export type Model = (typeof ALL_MODEL_NAMES)[number];
  * Precedence rules:
  * 1. Exact match against ALL_MODEL_NAMES → return as-is.
  * 2. Family heuristics for common variants:
+ *    - `gpt-5.6-sol`, `gpt-5.6-*` → `gpt-5.6`
  *    - `gpt-5.4-mini`, `gpt-5.4-turbo`, `gpt-5.4-*` → `gpt-5.4`
  *    - `gpt-*` (anything else GPT) → `gpt`
  *    - `o3`, `o4`, `o4-mini`, `o1`, `o1-mini`, `o1-pro` → `o-series`
@@ -52,6 +54,7 @@ export function resolveModel(input: string): Model | null {
   }
 
   // Family heuristics
+  if (/^gpt-5\.6(-|$)/.test(s)) return 'gpt-5.6';
   if (/^gpt-5\.4(-|$)/.test(s)) return 'gpt-5.4';
   if (/^gpt(-|$)/.test(s)) return 'gpt';
   if (/^o[0-9]+(-|$)/.test(s)) return 'o-series';