fix(shared): restrict cached Anthropic 1M context to GA 4.6 models only

src/shared/context-limit-resolver.test.ts

@@ -28,7 +28,7 @@ describe("resolveActualContextLimit", () => {
     resetContextLimitEnv()
   })
 
-  it("returns cached limit for Anthropic models when 1M mode is disabled (GA support)", () => {
+  it("returns cached limit for Anthropic 4.6 models when 1M mode is disabled (GA support)", () => {
     // given
     delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
     delete process.env[VERTEX_CONTEXT_ENV_KEY]
@@ -45,6 +45,23 @@ describe("resolveActualContextLimit", () => {
     expect(actualLimit).toBe(1_000_000)
   })
 
+  it("returns default 200K for older Anthropic models even when cached limit is higher", () => {
+    // given
+    delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
+    delete process.env[VERTEX_CONTEXT_ENV_KEY]
+    const modelContextLimitsCache = new Map<string, number>()
+    modelContextLimitsCache.set("anthropic/claude-sonnet-4-5", 500_000)
+
+    // when
+    const actualLimit = resolveActualContextLimit("anthropic", "claude-sonnet-4-5", {
+      anthropicContext1MEnabled: false,
+      modelContextLimitsCache,
+    })
+
+    // then
+    expect(actualLimit).toBe(200_000)
+  })
+
   it("returns default 200K for Anthropic models without cached limit and 1M mode disabled", () => {
     // given
     delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
@@ -92,6 +109,23 @@ describe("resolveActualContextLimit", () => {
     expect(actualLimit).toBe(200000)
   })
 
+  it("supports Anthropic 4.6 dot-version model IDs without explicit 1M mode", () => {
+    // given
+    delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
+    delete process.env[VERTEX_CONTEXT_ENV_KEY]
+    const modelContextLimitsCache = new Map<string, number>()
+    modelContextLimitsCache.set("anthropic/claude-opus-4.6", 1_000_000)
+
+    // when
+    const actualLimit = resolveActualContextLimit("anthropic", "claude-opus-4.6", {
+      anthropicContext1MEnabled: false,
+      modelContextLimitsCache,
+    })
+
+    // then
+    expect(actualLimit).toBe(1_000_000)
+  })
+
   it("returns null for non-Anthropic providers without a cached limit", () => {
     // given
     delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]