test(prompts): modernize stale gpt-4.1 fixtures to gpt-5.6

Gpt-family examples now probe openai/gpt-5.6 (current model); default-family
probes already use unknown-provider/unknown-model on main. Fixture values
only — no production code.

Refs CL-8751

Author: TheGreatAxios

src/agent/grok-residual.test.ts

@@ -44,7 +44,7 @@ describe("grok ceremony merge (CL-8296)", () => {
       { providerName: "anthropic", model: "claude-sonnet-4" },
       { providerName: "moonshot", model: "kimi-k2" },
       { providerName: "opencode-go", model: "muse-spark-1.3-contributor" },
-      { providerName: "openai", model: "gpt-4.1" },
+      { providerName: "openai", model: "gpt-5.6" },
     ] as const) {
       expect(shouldApplyGrokAntiThrash({ ...input, orchestrator: false })).toBe(
         false,

src/agent/model-family-policy.test.ts

@@ -125,7 +125,7 @@ describe("resolveModelFamilyPolicy", () => {
       });
       expect(orchestrator.promptResidual).toBeUndefined();
       // Default-family probe: anthropic/claude-sonnet-4 hits the claude row
-      // and openai/gpt-4.1 hits the gpt row (#1135), so an unrecognized
+      // and openai/gpt-5.6 hits the gpt row (#1135), so an unrecognized
       // provider is the probe that still resolves to the default family.
       const base = resolveModelFamilyPolicy({
         providerName: "unknown-provider",
@@ -154,13 +154,13 @@ describe("resolveModelFamilyPolicy", () => {
     expect(orchestrator.promptResidual).toBeUndefined();
   });
 
-  // The gpt family row has landed (#1135): openai/gpt-4.1 and codex/gpt-5.1
+  // The gpt family row has landed (#1135): openai/gpt-5.6 and codex/gpt-5.1
   // resolve to the gpt family with the narrate-before-tools residual, leaf
   // and orchestrator alike (no carve-out). Grok keeps its CL-8297 tool-budget
   // residual — the "no residual" claim below is default-family-only.
   test("gpt probes resolve to gpt with the narrate residual; grok keeps its tool budget", () => {
     for (const input of [
-      { providerName: "openai", model: "gpt-4.1" },
+      { providerName: "openai", model: "gpt-5.6" },
       { providerName: "codex", model: "gpt-5.1" },
     ] as const) {
       for (const orchestrator of [false, true]) {

src/subagent/provider-family.test.ts

@@ -41,7 +41,7 @@ describe("isXaiGrokLeafProvider", () => {
       }),
     ).toBe(false);
     expect(
-      isXaiGrokLeafProvider({ providerName: "openai", model: "gpt-4.1" }),
+      isXaiGrokLeafProvider({ providerName: "openai", model: "gpt-5.6" }),
     ).toBe(false);
   });
 
@@ -141,7 +141,7 @@ describe("detectModelFamily", () => {
       }),
     ).toBe("claude");
     expect(
-      detectModelFamily({ providerName: "openai", model: "gpt-4.1" }),
+      detectModelFamily({ providerName: "openai", model: "gpt-5.6" }),
     ).toBe("gpt");
     expect(
       detectModelFamily({
@@ -169,7 +169,7 @@ describe("isClaudeLeafProvider", () => {
       isClaudeLeafProvider({ providerName: "xai/default", model: "grok-4.5" }),
     ).toBe(false);
     expect(
-      isClaudeLeafProvider({ providerName: "openai", model: "gpt-4.1" }),
+      isClaudeLeafProvider({ providerName: "openai", model: "gpt-5.6" }),
     ).toBe(false);
     expect(
       isClaudeLeafProvider({ providerName: "codex", model: "gpt-5.1" }),