diff --git a/open-sse/executors/claudeIdentity.ts b/open-sse/executors/claudeIdentity.ts
index da79dfb37c..ef78832a90 100644
--- a/open-sse/executors/claudeIdentity.ts
+++ b/open-sse/executors/claudeIdentity.ts
@@ -285,18 +285,29 @@ export function parseUpstreamMetadataUserId(
 // ---------- anthropic-beta selector --------------------------------------
 
 /**
- * Models that support the heavy-agent beta tier (context-1m, effort,
- * advanced-tool-use). Only Opus/Sonnet are eligible — Haiku with OAuth
- * authentication rejects `context-1m-2025-08-07` with
- * "This authentication style is incompatible with the long context beta header"
- * (issue #2454). Matches real Claude Desktop, which omits these flags for Haiku.
+ * Models that support the heavy-agent beta tier (effort, advanced-tool-use).
+ * Only Opus/Sonnet are eligible — Haiku with OAuth authentication rejects
+ * heavy agent flags (issue #2454). Matches real Claude Code captures.
  */
 const HEAVY_AGENT_BETA_MODEL_PREFIXES = ["claude-opus", "claude-sonnet"];
+/**
+ * Models that support the context-1m beta tier. Only Opus is eligible;
+ * Sonnet trips long-context credit gates under OAuth full-agent traffic.
+ */
+const CONTEXT_1M_BETA_MODEL_PREFIXES = ["claude-opus"];
 
-function isHeavyAgentModel(model: unknown): boolean {
+function matchesModelPrefix(model: unknown, prefixes: string[]): boolean {
   if (typeof model !== "string") return false;
   const normalized = model.toLowerCase();
-  return HEAVY_AGENT_BETA_MODEL_PREFIXES.some((prefix) => normalized.includes(prefix));
+  return prefixes.some((prefix) => normalized.includes(prefix));
+}
+
+function isHeavyAgentModel(model: unknown): boolean {
+  return matchesModelPrefix(model, HEAVY_AGENT_BETA_MODEL_PREFIXES);
+}
+
+function isContext1mModel(model: unknown): boolean {
+  return matchesModelPrefix(model, CONTEXT_1M_BETA_MODEL_PREFIXES);
 }
 
 /**
@@ -304,9 +315,10 @@ function isHeavyAgentModel(model: unknown): boolean {
  * uses three patterns: minimal probe, structured-output, and full agent.
  * Sending the full set on every shape is itself a fingerprint.
  *
- * The heavy-agent flags (context-1m, effort, advanced-tool-use) are gated on
- * the model as well as the shape: Haiku must never receive `context-1m`, which
- * Anthropic rejects under OAuth authentication.
+ * The heavy-agent flags are gated on the model as well as the shape. In direct
+ * Claude Code captures, Sonnet receives effort/advanced-tool-use but not
+ * context-1m; sending context-1m to Sonnet trips Anthropic's long-context credit
+ * gate for accounts where direct Claude Code works.
  */
 export function selectBetaFlags(
   body: Record<string, unknown> | null | undefined,
@@ -325,24 +337,27 @@ export function selectBetaFlags(
   const isFullAgent = hasTools && hasSystem;
   const effectiveModel = model ?? (typeof b.model === "string" ? b.model : "");
   const isHeavyAgent = isFullAgent && isHeavyAgentModel(effectiveModel);
+  const isContext1m = isFullAgent && isContext1mModel(effectiveModel);
 
   const flags: string[] = [];
   if (isFullAgent) flags.push("claude-code-20250219");
   flags.push("oauth-2025-04-20");
-  if (isHeavyAgent) flags.push("context-1m-2025-08-07");
+  if (isContext1m) flags.push("context-1m-2025-08-07");
   flags.push(
     "interleaved-thinking-2025-05-14",
-    "redact-thinking-2026-02-12",
+    "thinking-token-count-2026-05-13",
     "context-management-2025-06-27",
     "prompt-caching-scope-2026-01-05"
   );
   if (hasStructuredOutput || isFullAgent) flags.push("advisor-tool-2026-03-01");
   if (hasStructuredOutput && !isFullAgent) flags.push("structured-outputs-2025-12-15");
   // extended-cache-ttl is sent for all full-agent shapes (incl. Haiku); the
-  // heavier advanced-tool-use / effort flags are Opus/Sonnet-only.
-  if (isFullAgent) flags.push("extended-cache-ttl-2025-04-11", "cache-diagnosis-2026-04-07");
+  // heavier afk-mode / advanced-tool-use / effort flags are Opus/Sonnet-only.
+  if (isFullAgent) {
+    flags.push("extended-cache-ttl-2025-04-11", "cache-diagnosis-2026-04-07");
+  }
   if (isHeavyAgent) {
-    flags.push("advanced-tool-use-2025-11-20", "effort-2025-11-24");
+    flags.push("afk-mode-2026-01-31", "advanced-tool-use-2025-11-20", "effort-2025-11-24");
   }
   return flags.join(",");
 }
diff --git a/open-sse/services/claudeCodeCompatible.ts b/open-sse/services/claudeCodeCompatible.ts
index dad7da6f6f..33b6ad1989 100644
--- a/open-sse/services/claudeCodeCompatible.ts
+++ b/open-sse/services/claudeCodeCompatible.ts
@@ -50,13 +50,7 @@ const CLAUDE_CODE_COMPATIBLE_DEFAULT_SYSTEM_BLOCKS = [
     text: "You are a Claude agent, built on Anthropic's Claude Agent SDK.",
   },
 ];
-const CONTEXT_1M_SUPPORTED_MODELS = [
-  "claude-opus-4-7",
-  "claude-opus-4-6",
-  "claude-sonnet-4-6",
-  "claude-sonnet-4-5",
-  "claude-sonnet-4",
-];
+const CONTEXT_1M_SUPPORTED_MODELS = ["claude-opus-4-7", "claude-opus-4-6"];
 export const CLAUDE_CODE_COMPATIBLE_STAINLESS_TIMEOUT_SECONDS = getStainlessTimeoutSeconds(
   process.env
 );
diff --git a/tests/unit/claude-beta-flags-2454.test.ts b/tests/unit/claude-beta-flags-2454.test.ts
index 3dbd3e4e9d..318f2881c9 100644
--- a/tests/unit/claude-beta-flags-2454.test.ts
+++ b/tests/unit/claude-beta-flags-2454.test.ts
@@ -5,8 +5,9 @@ const { selectBetaFlags } = await import("../../open-sse/executors/claudeIdentit
 
 // Regression for #2454: Haiku with OAuth rejects `context-1m-2025-08-07` with
 // 400 "This authentication style is incompatible with the long context beta header".
-// The heavy-agent beta tier (context-1m, effort, advanced-tool-use) must be gated on
+// The heavy-agent beta tier (effort, advanced-tool-use) must be gated on
 // Opus/Sonnet only; Haiku still receives the general full-agent flags.
+// context-1m is Opus-only in captured Claude Code traffic.
 
 function fullAgentBody(model: string) {
   return {
@@ -19,6 +20,7 @@ function fullAgentBody(model: string) {
 test("#2454 Haiku full-agent omits heavy-agent beta flags", () => {
   const flags = selectBetaFlags(fullAgentBody("claude-haiku-4-5-20251001"));
   assert.ok(!flags.includes("context-1m-2025-08-07"), "Haiku must NOT receive context-1m");
+  assert.ok(!flags.includes("afk-mode-2026-01-31"), "Haiku must NOT receive afk-mode");
   assert.ok(!flags.includes("effort-2025-11-24"), "Haiku must NOT receive effort");
   assert.ok(
     !flags.includes("advanced-tool-use-2025-11-20"),
@@ -31,11 +33,14 @@ test("#2454 Haiku full-agent omits heavy-agent beta flags", () => {
   assert.ok(flags.includes("extended-cache-ttl-2025-04-11"));
 });
 
-test("#2454 Sonnet full-agent includes heavy-agent beta flags", () => {
+test("#2454 Sonnet full-agent includes heavy-agent flags but omits context-1m", () => {
   const flags = selectBetaFlags(fullAgentBody("claude-sonnet-4-6"));
-  assert.ok(flags.includes("context-1m-2025-08-07"), "Sonnet should receive context-1m");
+  assert.ok(!flags.includes("context-1m-2025-08-07"), "Sonnet must NOT receive context-1m");
   assert.ok(flags.includes("effort-2025-11-24"));
   assert.ok(flags.includes("advanced-tool-use-2025-11-20"));
+  assert.ok(flags.includes("thinking-token-count-2026-05-13"));
+  assert.ok(flags.includes("afk-mode-2026-01-31"));
+  assert.ok(!flags.includes("redact-thinking-2026-02-12"));
 });
 
 test("#2454 Opus full-agent includes heavy-agent beta flags", () => {
diff --git a/tests/unit/executor-default-base.test.ts b/tests/unit/executor-default-base.test.ts
index ebfeecd209..057916bf6c 100644
--- a/tests/unit/executor-default-base.test.ts
+++ b/tests/unit/executor-default-base.test.ts
@@ -569,7 +569,7 @@ test("DefaultExecutor.execute uses CC-compatible connection defaults to append 1
 
   assert.equal(calls[0].headers["anthropic-beta"].includes(CONTEXT_1M_BETA_HEADER), false);
   assert.equal(calls[1].headers["anthropic-beta"].includes(CONTEXT_1M_BETA_HEADER), true);
-  assert.equal(calls[2].headers["anthropic-beta"], CONTEXT_1M_BETA_HEADER);
+  assert.equal(calls[2].headers["anthropic-beta"], undefined);
 });
 
 test("DefaultExecutor.execute only injects adaptive thinking defaults for Claude models that support x-high effort", async () => {