diff --git a/src/hooks/preemptive-compaction.aws-bedrock.test.ts b/src/hooks/preemptive-compaction.aws-bedrock.test.ts
index 9ce47ac8c..ce4174a29 100644
--- a/src/hooks/preemptive-compaction.aws-bedrock.test.ts
+++ b/src/hooks/preemptive-compaction.aws-bedrock.test.ts
@@ -42,7 +42,7 @@ describe("preemptive-compaction aws-bedrock-anthropic", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 1000,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
diff --git a/src/hooks/preemptive-compaction.test.ts b/src/hooks/preemptive-compaction.test.ts
index ebf90c208..f7b7344c6 100644
--- a/src/hooks/preemptive-compaction.test.ts
+++ b/src/hooks/preemptive-compaction.test.ts
@@ -142,7 +142,7 @@ describe("preemptive-compaction", () => {
     const hook = createPreemptiveCompactionHook(ctx as never, {} as never)
     const sessionID = "ses_high"
 
-    // 170K input + 10K cache = 180K → 90% of 200K
+    // 800K input + 10K cache = 810K → 81% of 1M (GA limit for 4.6 models)
     await hook.event({
       event: {
         type: "message.updated",
@@ -154,7 +154,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 1000,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -190,7 +190,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 1000,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -267,7 +267,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 0,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -313,7 +313,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 0,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -357,7 +357,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 0,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -386,7 +386,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 0,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -504,7 +504,7 @@ describe("preemptive-compaction", () => {
               modelID: "claude-sonnet-4-6",
               finish: true,
               tokens: {
-                input: 170000,
+                input: 800000,
                 output: 0,
                 reasoning: 0,
                 cache: { read: 10000, write: 0 },
@@ -544,7 +544,7 @@ describe("preemptive-compaction", () => {
                 modelID: "claude-sonnet-4-6",
                 finish: true,
                 tokens: {
-                  input: 170000,
+                  input: 800000,
                   output: 0,
                   reasoning: 0,
                   cache: { read: 10000, write: 0 },
@@ -576,7 +576,7 @@ describe("preemptive-compaction", () => {
     const hook = createPreemptiveCompactionHook(ctx as never, {} as never)
     const sessionID = "ses_recompact"
 
-    // given - first compaction cycle
+    // given - first compaction cycle (810K > 78% of 1M GA limit)
     await hook.event({
       event: {
         type: "message.updated",
@@ -588,7 +588,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 0,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -619,7 +619,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 0,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
@@ -657,7 +657,7 @@ describe("preemptive-compaction", () => {
             modelID: "claude-sonnet-4-6",
             finish: true,
             tokens: {
-              input: 170000,
+              input: 800000,
               output: 0,
               reasoning: 0,
               cache: { read: 10000, write: 0 },
diff --git a/src/shared/context-limit-resolver.test.ts b/src/shared/context-limit-resolver.test.ts
index d924d8a99..10ded16e5 100644
--- a/src/shared/context-limit-resolver.test.ts
+++ b/src/shared/context-limit-resolver.test.ts
@@ -158,6 +158,76 @@ describe("resolveActualContextLimit", () => {
     expect(actualLimit).toBe(200_000)
   })
 
+  it("returns GA 1M for claude-sonnet-4-6 without cached limit (GA context window)", () => {
+    // given
+    delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
+    delete process.env[VERTEX_CONTEXT_ENV_KEY]
+
+    // when
+    const actualLimit = resolveActualContextLimit("anthropic", "claude-sonnet-4-6", {
+      anthropicContext1MEnabled: false,
+    })
+
+    // then
+    expect(actualLimit).toBe(1_000_000)
+  })
+
+  it("returns GA 1M for claude-opus-4-6 without cached limit (GA context window)", () => {
+    // given
+    delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
+    delete process.env[VERTEX_CONTEXT_ENV_KEY]
+
+    // when
+    const actualLimit = resolveActualContextLimit("anthropic", "claude-opus-4-6", {
+      anthropicContext1MEnabled: false,
+    })
+
+    // then
+    expect(actualLimit).toBe(1_000_000)
+  })
+
+  it("returns GA 1M for claude-opus-4-7 without cached limit (GA context window)", () => {
+    // given
+    delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
+    delete process.env[VERTEX_CONTEXT_ENV_KEY]
+
+    // when
+    const actualLimit = resolveActualContextLimit("anthropic", "claude-opus-4-7", {
+      anthropicContext1MEnabled: false,
+    })
+
+    // then
+    expect(actualLimit).toBe(1_000_000)
+  })
+
+  it("returns GA 1M for claude-sonnet-4-6-high without cached limit (GA context window)", () => {
+    // given
+    delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
+    delete process.env[VERTEX_CONTEXT_ENV_KEY]
+
+    // when
+    const actualLimit = resolveActualContextLimit("anthropic", "claude-sonnet-4-6-high", {
+      anthropicContext1MEnabled: false,
+    })
+
+    // then
+    expect(actualLimit).toBe(1_000_000)
+  })
+
+  it("returns GA 1M for GA models on google-vertex-anthropic without cached limit", () => {
+    // given
+    delete process.env[ANTHROPIC_CONTEXT_ENV_KEY]
+    delete process.env[VERTEX_CONTEXT_ENV_KEY]
+
+    // when
+    const actualLimit = resolveActualContextLimit("google-vertex-anthropic", "claude-sonnet-4-6", {
+      anthropicContext1MEnabled: false,
+    })
+
+    // 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]
diff --git a/src/shared/context-limit-resolver.ts b/src/shared/context-limit-resolver.ts
index 2d440658b..ee7e23a18 100644
--- a/src/shared/context-limit-resolver.ts
+++ b/src/shared/context-limit-resolver.ts
@@ -1,6 +1,7 @@
 import process from "node:process"
 
 const DEFAULT_ANTHROPIC_ACTUAL_LIMIT = 200_000
+const ANTHROPIC_GA_1M_LIMIT = 1_000_000
 export type ContextLimitModelCacheState = {
   anthropicContext1MEnabled: boolean
   modelContextLimitsCache?: Map<string, number>
@@ -15,11 +16,11 @@ function getAnthropicActualLimit(modelCacheState?: ContextLimitModelCacheState):
   return (modelCacheState?.anthropicContext1MEnabled ?? false) ||
     process.env.ANTHROPIC_1M_CONTEXT === "true" ||
     process.env.VERTEX_ANTHROPIC_1M_CONTEXT === "true"
-    ? 1_000_000
+    ? ANTHROPIC_GA_1M_LIMIT
     : DEFAULT_ANTHROPIC_ACTUAL_LIMIT
 }
 
-function supportsCachedAnthropicLimit(modelID: string): boolean {
+function hasGA1MContext(modelID: string): boolean {
   return /^claude-(opus|sonnet)-4(?:-|\.)(?:6|7)(?:-high)?$/.test(modelID)
 }
 
@@ -30,10 +31,12 @@ export function resolveActualContextLimit(
 ): number | null {
   if (isAnthropicProvider(providerID)) {
     const explicit1M = getAnthropicActualLimit(modelCacheState)
-    if (explicit1M === 1_000_000) return explicit1M
+    if (explicit1M === ANTHROPIC_GA_1M_LIMIT) return explicit1M
 
     const cachedLimit = modelCacheState?.modelContextLimitsCache?.get(`${providerID}/${modelID}`)
-    if (cachedLimit && supportsCachedAnthropicLimit(modelID)) return cachedLimit
+    if (cachedLimit && hasGA1MContext(modelID)) return cachedLimit
+
+    if (hasGA1MContext(modelID)) return ANTHROPIC_GA_1M_LIMIT
 
     return DEFAULT_ANTHROPIC_ACTUAL_LIMIT
   }